Comparison of adhesive properties of water- and phosphate-buffer-washed cottonseed meals with cottonseed protein isolate on maple and poplar veneers

USDA-ARS?s Scientific Manuscript database

Water- and phosphate buffer (35 mM Na2HPO4/NaH2PO4, pH 7.5)-washed cottonseed meals (abbreviated as WCM and BCM, respectively) could be low-cost and environmentally friendly protein-based adhesives as their preparation does not involve corrosive alkali and acid solutions that are needed for cottonse...

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase.

PubMed

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes' ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion.

Comparing the acidities of aqueous, frozen, and freeze-dried phosphate buffers: Is there a "pH memory" effect?

PubMed

Vetráková, Ľubica; Vykoukal, Vít; Heger, Dominik

2017-09-15

The concept of "pH memory" has been established in the literature for the correlation between the pH of a pre-lyophilization solution and the ionization state of freeze-dried powder (lyophile). In this paper, the concept of "pH memory" is explored for the system of an aqueous solution, a frozen solution, and a lyophile. Sodium and potassium phosphate buffers in the pH range of 5-9 were frozen and lyophilized with sulfonephthalein indicators as acidity probes, and their Hammett acidity functions were compared to the initial pH of the aqueous solution. The results show that the acidities of the lyophiles are somewhat changed compared to the initial pHs, but the acidities in the frozen state differ more substantially. The Hammett acidity functions of the frozen buffers were found to be markedly dissimilar from the initial pH, especially in the sodium phosphate frozen at 233K, where an increase in the initial pH led to a decrease in the Hammett acidity function of the frozen state at a certain pH range. The large acidification observed after freezing the sodium phosphate buffer was not detected in the lyophiles after the sample had been dried; the phenomenon is explained considering the formed crystals analyzed by X-ray powder diffraction. The results suggest that monitoring the final acidity of a lyophile is not sufficient to predict all the acidity changes throughout the whole lyophilization process. The importance of well-controlled freezing and lyophilization conditions follows from the results of the research. Copyright © 2017 Elsevier B.V. All rights reserved.

Matching phosphate and maleate buffer systems for dissolution of weak acids: Equivalence in terms of buffer capacity of bulk solution or surface pH?

PubMed

Cristofoletti, Rodrigo; Dressman, Jennifer B

2016-06-01

The development of in vitro dissolution tests able to anticipate the in vivo fate of drug products has challenged pharmaceutical scientists over time, especially in the case of ionizable compounds. In the seminal model proposed by Mooney et al. thirty-five years ago, the pH at the solid-liquid interface (pH0) was identified as a key parameter in predicting dissolution rate. In the current work it is demonstrated that the in vitro dissolution of the weak acid ibuprofen in maleate and phosphate buffer systems is a function of the pH0, which in turn is affected by properties of the drug and the medium. The reported pH0 for ibuprofen dissolution in bicarbonate buffer, the predominant buffer species in the human small intestine under fasting conditions, can be achieved by reducing the phosphate buffer concentration to 5.0mM or the maleate buffer concentration to 2.2mM. Using this approach to identify the appropriate buffer/buffer capacity combination for in vitro experiments in FaSSIF-type media, it would be possible to increase the physiological relevance of this important biopharmaceutics tool. However, the necessity of monitoring and adjusting the bulk pH during the experiments carried out in 5.0mM phosphate or 2.2mM maleate buffers must also be taken into consideration. Copyright © 2016 Elsevier B.V. All rights reserved.

Reductive dechlorination of carbon tetrachloride using buffered alkaline ascorbic acid.

PubMed

Lin, Ya-Ting; Liang, Chenju

2015-10-01

Alkaline ascorbic acid (AA) was recently discovered as a novel in-situ chemical reduction (ISCR) reagent for remediating chlorinated solvents in the subsurface. For this ISCR process, the maintenance of an alkaline pH is essential. This study investigated the possibility of the reduction of carbon tetrachloride (CT) using alkaline AA solution buffered by phosphate and by NaOH. The results indicated that CT was reduced by AA, and chloroform (CF) was a major byproduct at a phosphate buffered pH of 12. However, CT was completely reduced by AA in 2M NaOH without CF formation. In the presence of iron/soil minerals, iron could be reduced by AA and Fe(2+) tends to precipitate on the mineral surface to accelerate CT degradation. A simultaneous transfer of hydrogenolysis and dichloroelimination would occur under phosphate buffered pH 12. This implies that a high alkaline environment is a crucial factor for maintaining the dominant pathway of two electron transfer from dianionic AA to dehydroascorbic acid, and to undergo dichloroelimination of CT. Moreover, threonic acid and oxalic acid were identified to be the major AA decomposition products in alkaline solutions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Interaction of two diclofenac acid salts with copolymers of ammoniomethacrylate: effect of additives and release profiles.

PubMed

Khalil, E; Sallam, A

1999-04-01

The copolymer of ammoniomethacrylate Eudragit RL (ERL) interacted with diclofenac acid salts (sodium and diethylamine salts) in aqueous solutions, forming a complex. Sorption experiments were done in aqueous solutions of either sodium lauryl sulfate (SLS), Tween 20, or Tween 80. The SLS competed strongly with the drug, even at low concentrations, and reduced significantly the amount of drug sorbed by ERL. Tweens at high concentrations exhibited two phase profiles: the sorption phase, which was short and during which drug concentration dropped sharply, and the release phase, during which the drug was released slowly over 24 hr and which was accompanied by dispersion of ERL particles into the colloidal dispersion. The interaction was dependent on temperature, ionic strength, and nature of the additives. The extent of interaction in water and phosphate buffer solutions was in the following order: water > pH 6 > pH 7-8. In-vitro dissolution studies of the dried complex were done over 24 hr. In water, the drug remained bound to the polymer. In aqueous surfactant solutions (SLS, Tween 20, and Tween 80) and phosphate buffer at pH 6.8, a linear relationship between drug concentration and the square root of time was obtained, indicating a matrix diffusion-controlled mechanism. However, 100% release was not reached, and resorption was observed in the phosphate buffer solution.

In vitro behaviour of three biocompatible glasses in composite implants.

PubMed

Varila, Leena; Lehtonen, Timo; Tuominen, Jukka; Hupa, Mikko; Hupa, Leena

2012-10-01

Poly(L,DL-lactide) composites containing filler particles of bioactive glasses 45S5 and S53P4 were compared with a composite containing a slowly dissolving glass S68. The in vitro reactivity of the composites was studied in simulated body fluid, Tris-buffered solution, and phosphate buffered saline. The high processing temperature induced thermal degradation giving cavities in the composites containing 45S5 and S53P4, while good adhesion of S68 to the polymer was observed. The cavities partly affected the in vitro reactivity of the composites. The degradation of the composites containing the bioactive glasses was faster in phosphate buffered saline than in the two other solutions. Hydroxyapatite precipitation suggesting bone tissue bonding capability was observed on these two composites in all three solutions. The slower dissolution of S68 glass particles and the limited hydroxyapatite precipitation suggested that this glass has potential as a reinforcing composition with the capability to guide bone tissue growth in biodegradable polymer composites.

Effect of Phosphate-Buffered Solution Corrosion on the Ratcheting Fatigue Behavior of a Duplex Mg-Li-Al Alloy

NASA Astrophysics Data System (ADS)

Yuan, Xin; Yu, Dunji; Gao, Li-Lan; Gao, Hong

2016-05-01

This work reports the uniaxial ratcheting and fatigue behavior of a duplex Mg-Li-Al alloy under the influence of phosphate-buffered solution corrosion. Microstructural observations reveal pitting and filament corrosion defects, which impair the load-bearing capacity of the alloy and cause stress concentration, thus leading to an accelerated accumulation of ratcheting strain and shortened fatigue life under the same nominal loading conditions. Comparing Smith model, Smith-Watson-Topper model, and Paul-Sivaprasad-Dhar model, a ratcheting fatigue life prediction model based on the Broberg damage rule and the Paul-Sivaprasad-Dhar model was proposed, and the model yielded a superior prediction for the studied magnesium alloy.

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase

PubMed Central

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

Background It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. Materials and methods We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes’ ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. Results The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. Conclusion These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion. PMID:24333060

Albumin adsorption onto surfaces of urine collection and analysis containers☆

PubMed Central

Robinson, Mary K.; Caudill, Samuel P.; Koch, David D.; Ritchie, James; Hortin, Glen; Eckfeldt, John H.; Sandberg, Sverre; Williams, Desmond; Myers, Gary; Miller, W. Greg

2017-01-01

Background Adsorption of albumin onto urine collection and analysis containers may cause falsely low concentrations. Methods We added 125I-labeled human serum albumin to urine and to phosphate buffered solutions, incubated them with 22 plastic container materials and measured adsorption by liquid scintillation counting. Results Adsorption of urine albumin (UA) at 5–6 mg/l was <0.9%; and at 90 mg/l was <0.4%. Adsorption was generally less at pH 8 than pH 5 but only 3 cases had p <0.05. Adsorption from 11 unaltered urine samples with albumin 5–333 mg/l was <0.8%. Albumin adsorption for the material with greatest binding was extrapolated to the surface areas of 100 ml and 2 l collection containers, and to instrument sample cups and showed <1% change in concentration at 5 mg/l and <0.5% change at 20 mg/l or higher concentrations. Adsorption of albumin from phosphate buffered solutions (2–28%) was larger than that from urine. Conclusions Albumin adsorption differed among urine samples and plastic materials, but the total influence of adsorption was <1% for all materials and urine samples tested. Adsorption of albumin from phosphate buffered solutions was larger than that from urine and could be a limitation for preparations used as calibrators. PMID:24513540

Albumin adsorption onto surfaces of urine collection and analysis containers.

PubMed

Robinson, Mary K; Caudill, Samuel P; Koch, David D; Ritchie, James; Hortin, Glen; Eckfeldt, John H; Sandberg, Sverre; Williams, Desmond; Myers, Gary; Miller, W Greg

2014-04-20

Adsorption of albumin onto urine collection and analysis containers may cause falsely low concentrations. We added (125)I-labeled human serum albumin to urine and to phosphate buffered solutions, incubated them with 22 plastic container materials and measured adsorption by liquid scintillation counting. Adsorption of urine albumin (UA) at 5-6 mg/l was <0.9%; and at 90 mg/l was <0.4%. Adsorption was generally less at pH8 than pH5 but only 3 cases had p<0.05. Adsorption from 11 unaltered urine samples with albumin 5-333 mg/l was <0.8%. Albumin adsorption for the material with greatest binding was extrapolated to the surface areas of 100 ml and 2l collection containers, and to instrument sample cups and showed <1% change in concentration at 5 mg/l and <0.5% change at 20 mg/l or higher concentrations. Adsorption of albumin from phosphate buffered solutions (2-28%) was larger than that from urine. Albumin adsorption differed among urine samples and plastic materials, but the total influence of adsorption was <1% for all materials and urine samples tested. Adsorption of albumin from phosphate buffered solutions was larger than that from urine and could be a limitation for preparations used as calibrators. Copyright © 2014 Elsevier B.V. All rights reserved.

An efficient buffer-mediated control between free radical substitution and proton-coupled electron transfer: dehalogenation of iodoethane by the α-hydroxyethyl radical in aqueous solution.

PubMed

Ljubić, Ivan; Matasović, Brunislav; Bonifačić, Marija

2013-11-07

A remarkable buffer-mediated control between free-radical substitution (FRS) and proton-coupled electron transfer (PCET) is demonstrated for the reaction between iodoethane and the α-hydroxyethyl radical in neutral aqueous solution in the presence of bicarbonate or phosphate buffer. The reaction is initiated by the γ-radiolysis of the water solvent, and the products, either the iodine atom (FRS) or anion (PCET), are analysed using ion chromatographic and spectrophotometric techniques. A detailed insight into the mechanism is gained by employing density functional theory (M06-2X), Møller-Plesset perturbation treatment to the second order (MP2), and multireference methods (CASSCF/CASPT2). Addition of a basic buffer anion is indispensable for the reaction to occur and the competition between the two channels depends subtly on its proton accepting affinity, with FRS being the dominant channel in the phosphate and PCET in the bicarbonate containing solutions. Unlike the former, the latter channel sustains a chain-like process which significantly enhances the dehalogenation. The present systems furnish an example of the novel PCET/FRS dichotomy, as well as insights into possibilities of its efficient control.

Improved quantitative recovery of Listeria monocytogenes from stainless steel surfaces using a one-ply composite tissue.

PubMed

Vorst, Keith L; Todd, Ewen C D; Rysert, Elliot T

2004-10-01

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.

Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF4 Nanoparticles and their Colloidal Stability in Phosphate Buffer

PubMed Central

2015-01-01

Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (Mn = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (Mn = 2000) and biotin-terminated PEG (Mn = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000–PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir2012, 28, 12861−1287022906305) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline. PMID:24898128

Functional PEG-PAMAM-tetraphosphonate capped NaLnF₄ nanoparticles and their colloidal stability in phosphate buffer.

PubMed

Zhao, Guangyao; Tong, Lemuel; Cao, Pengpeng; Nitz, Mark; Winnik, Mitchell A

2014-06-17

Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (M(n) = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (M(n) = 2000) and biotin-terminated PEG (M(n) = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000-PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir 2012, 28, 12861-12870) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline.

Toposelective electrochemical desorption of thiol SAMs from neighboring polycrystalline gold surfaces.

PubMed

Tencer, Michal; Berini, Pierre

2008-11-04

We describe a method for the selective desorption of thiol self-assembled monolayers from gold surfaces having micrometer-scale separations on a substrate. In an electrolyte solution, the electrical resistance between the adjacent areas can be much lower than the resistance between a surface and the counter electrode. Also, both reductive and oxidative thiol desorption may occur. Therefore, the potentials of the surfaces must be independently controlled with a multichannel potentiostat and operating windows for a given thiol/electrolyte system must be established. In this study operating windows were established for 1-dodecanethiol-based SAMs in phosphate buffer, phosphate-buffered saline, and sodium hydroxide solution, and selective SAM removal was successfully performed in a four-electrode configuration.

Phosphorus Amendment Efficacy for In Situ Remediation of ...

EPA Pesticide Factsheets

A validated method is needed to measure reductions of in vitro bioaccessible (IVBA) Pb in urban soil remediated with amendments. This study evaluated the effect of in vitro extraction solution pH and glycine buffer on bioaccesible Pb in P-treated soils. Two Pb-contaminated soils (790-1300 mg Pb kg-1), one from a garden and one from a city lot in Cleveland, OH, were incubated in a bench scale experiment for 1 yr. Six phosphate amendments, including bone meal, fish bone, poultry litter, monoammonium phosphate, diammonium phosphate, and triple superphosphate, were added to containers at two application rates. Lead IVBA was assessed using USEPA Method 1340 and three modified versions of this method. Modifications included using solutions with pH 1.5 and 2.5 as well as using solutions with and without 0.4 mol L-1 glycine. Soil amendments were effective in reducing IVBA Pb in these soils as measured by pH 1.5 with glycine buffer. The greatest reductions in IVBA Pb, from 5 to 26%, were found using pH 2.5 extractions. Lead mineral results showed several soil amendments promoted Pb phosphate formation, an indicator of remediation success. A significant negative linear relationship between reduction in IVBA Pb and Pb-phosphate formation was found only for pH 2.5 without glycine extraction solution. A modified USEPA Method 1340 without glycine and using pH 2.5 has the potential to predict P soil treatment efficacy and reductions in bioavailable Pb. Developing mana

Layer by layer assembled films between hemoglobin and multiwall carbon nanotubes for pH-switchable biosensing.

PubMed

Pan, Zhongqin; Liu, Xiaojun; Xie, Jing; Bao, Ning; He, Hong; Li, Xiaodong; Zeng, Jiang; Gu, Haiying

2015-05-01

Although pH-switchable behaviors have been reported based on multilayer films modified electrodes, their pH-switchable biosensing is still difficult due to the existence of the electroactive mediator. In this study, we report the pH-dependable determination of hydrogen peroxide (H2O2) based on a four-bilayer film fabricated through layer by layer assembly between hemoglobin (Hb) and multiwall carbon nanotubes (MWCNTs). We observed that response of electroactive probe Fe(CN)6(3-) at the multilayer films was very sensitive and reversible to pH values of phosphate buffer solutions phosphate buffer solution with cyclic voltammetry. The reduction peak height of Fe(CN)6(3-) at the multilayer film could reach ∼221μA at pH 3.0 while 0μA at pH 9.0. The linear range for the detection of H2O2 at pH 3.0 was from 12.5μM to 10.4mM, which was much wider than that at pH 9.0. Our results demonstrated that the detection of H2O2 with the proposed modified electrode is dependent on pH values of phosphate buffer solution. Moreover, the component of multilayer films has impacts on the performance of biosensors with pH-switchable behaviors. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of albumin on the electrochemical behaviour of Zr in phosphate buffered saline solutions.

PubMed

Wang, Lu-Ning; Huang, Xian-Qiu; Shinbine, Alyssa; Luo, Jing-Li

2013-02-01

The corrosion behaviour of Zr in phosphate buffered saline (PBS) solutions with various concentrations (0-4 g L(-1)) of albumin was studied by electrochemical techniques and surface analysis. Addition of albumin to PBS solutions moved the open circuit potential (OCP) to less nobler direction. OCP, polarization resistance and impedance increased and the corrosion current decreased over immersion duration. At early stages of immersion, the resistance was increased with the concentration of albumin because of the high adsorption kinetics of albumin on metal. After the long term immersion, the resistance in PBS without albumin was higher than PBS with albumin owing to the anodic dissolution effect of albumin on metal. According to the analysis of effective capacitances, a normal distribution of time-constants was proposed to estimate the surface film on Zr. A corrosion mechanism of Zr in PBS with different albumin was proposed based on electrochemical analysis.

Photophysical investigations of squaraine and cyanine dyes and their interaction with bovine serum albumin

NASA Astrophysics Data System (ADS)

Saikiran, M.; Sato, D.; Pandey, S. S.; Kato, T.

2016-04-01

A model far-red sensitive symmetrical squaraine dye (SQ-3) and unsymmetrical near infra-red sensitive cyanine dye (UCD-1) bearing direct-COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations including their interaction with bovine serum albumin (BSA) as a model protein in phosphate buffer solution (PBS). Both of the dyes exhibit strong interaction with BSA in phosphate buffer with high apparent binding constant. A judicious tuning of hydrophobic main backbone with reactive functionality for associative interaction with active site of BSA has been found to be necessary for BSA detection in PBS.

Osmotic agents and buffers in peritoneal dialysis solution: monocyte cytokine release and in vitro cytotoxicity.

PubMed

Plum, J; Schoenicke, G; Grabensee, B

1997-09-01

Peritonitis remains a major problem in peritoneal dialysis. The incidence of peritonitis may be reduced by the use of more "biocompatible" peritoneal dialysis solutions that do not impair local host defense mechanisms, such as occurs with conventional lactate-buffered glucose solutions. In the present study, we investigated the use of bicarbonate and lactate as buffer systems and glucose, amino acids, and glucose polymer as osmotic agents on specific cellular functions of isolated fresh blood monocytes in vitro. The bicarbonate-buffered solutions had a physiologic pH (7.0 to 7.6). Lactate-buffered solutions were tested with a pH between 5.5 and 7.3. RPMI 1640 (Roswell Park Memorial Institute, supplied by Biochrom, Berlin, Germany) and phosphate-buffered saline were used as control mediums. The test solutions were incubated with 200,000 monocytes/mL for 45 minutes followed by a 1:1 mix with RPMI 1640 (with supplements) during a 24- or 4-hour tetrazolium bromide test (MTT test) recovery period. Constitutive and lipopolysaccharide (LPS)-stimulated release of interleukin-1beta (IL-1beta) and IL-6 in the supernatants as parameters of cellular host defense and lactate dehydrogenase concentrations and MTT-formazan production as parameters for cell cytotoxicity were measured. Significantly higher IL-6 and IL-1beta release was found in the bicarbonate-buffered solutions, both under basal conditions and after LPS stimulation, compared with the lactate-buffered solutions (LPS stimulation: 1% amino acids/34 mmol/L bicarbonate, IL-1beta: 1,166 +/- 192 pg/mL; 1.5% glucose/34 mmol/L bicarbonate, IL-1beta: 752 +/- 107 pg/mL; 1.5% glucose/35 mmol/L lactate/pH 5.5, IL-1beta: 174 +/- 51 pg/mL). Some of these differences could even be detected in spent dialysate after a 6-hour dwell in continuous ambulatory peritoneal dialysis patients (n = 10). A lower degree of cellular cytotoxicity (lactate dehydrogenase activity) and better-preserved metabolic activity (MTT test) also were found for the bicarbonate-buffered solutions. Amino acids (1%) proved to be comparable to glucose (1.5%) as an osmotic agent at a neutral pH with regard to LPS-stimulated cytokine release and cytotoxicity. The incubation with a glucose polymer solution (7.5% glucose polymer in phosphate-buffered saline, pH 7.3) resulted in a significantly lowered cytokine release (LPS stimulation: IL-1beta, 69 +/- 19 pg/mL) compared with the other solutions with neutral pH (P < 0.01). These results suggest that bicarbonate as a buffer provided better biocompatibility with regard to mononuclear cytokine release and viability compared with lactate. Amino acids and glucose were equivalent to these parameters at a physiologic pH. The glucose polymer solution, however, was associated with a marked depression of cytokine release.

Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure

PubMed Central

Gayán, Elisa; Condón, Santiago; Álvarez, Ignacio; Nabakabaya, Maria

2013-01-01

Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (ΔV°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ΔV° values are approximately 5.0 to 7.0 cm3 mol−1, than in phosphate or dimethyl glutarate (DMG), whose ΔV° values are about −25 cm3 mol−1. However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4 and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4 than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes. PMID:23624471

Influence of the chloride ion concentration on the corrosion of high-purity Mg, ZE41 and AZ91 in buffered Hank's solution.

PubMed

Taltavull, C; Shi, Z; Torres, B; Rams, J; Atrens, A

2014-02-01

This research studied the influence of the chloride ion concentration on the corrosion behaviour of high-purity magnesium (Mg) and two Mg alloys in Hank's solution, using hydrogen evolution and weight loss. A buffer based on CO2 and NaHCO3 was used to maintain the pH constant. The corrosion behaviour was governed by a partially protective surface film, and film breakdown by the chloride ions. The carbonated calcium phosphate layer that formed in Hank's solution was important in determining the protective properties of the surface film.

Exposure to buffer solution alters tendon hydration and mechanics.

PubMed

Safa, Babak N; Meadows, Kyle D; Szczesny, Spencer E; Elliott, Dawn M

2017-08-16

A buffer solution is often used to maintain tissue hydration during mechanical testing. The most commonly used buffer solution is a physiological concentration of phosphate buffered saline (PBS); however, PBS increases the tissue's water content and decreases its tensile stiffness. In addition, solutes from the buffer can diffuse into the tissue and interact with its structure and mechanics. These bathing solution effects can confound the outcome and interpretation of mechanical tests. Potential bathing solution artifacts, including solute diffusion, and their effect on mechanical properties, are not well understood. The objective of this study was to measure the effects of long-term exposure of rat tail tendon fascicles to several concentrations (0.9-25%) of NaCl, sucrose, polyethylene glycol (PEG), and SPEG (NaCl+PEG) solutions on water content, solute diffusion, and mechanical properties. We found that with an increase in solute concentration the apparent water content decreased for all solution types. Solutes diffused into the tissue for NaCl and sucrose, however, no solute diffusion was observed for PEG or SPEG. The mechanical properties changed for both NaCl solutions, in particular after long-term (8h) incubation the modulus and equilibrium stress decreased compared to short-term (15min) for 25% NaCl, and the cross sectional area increased for 0.9% NaCl. However, the mechanical properties were unchanged for both PEG and SPEG except for minor alterations in stress relaxation parameters. This study shows that NaCl and sucrose buffer solutions are not suitable for long-term mechanical tests. We therefore propose using PEG or SPEG as alternative buffer solutions that after long-term incubation can maintain tissue hydration without solute diffusion and produce a consistent mechanical response. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical Behavior of Pure Copper in Phosphate Buffer Solutions: A Comparison Between Micro- and Nano-Grained Copper

NASA Astrophysics Data System (ADS)

Imantalab, O.; Fattah-alhosseini, A.; Keshavarz, M. K.; Mazaheri, Y.

2016-02-01

In this work, electrochemical behavior of annealed (micro-) and nano-grained pure copper (fabricated by accumulative roll bonding process) in phosphate buffer solutions of various pH values ranging from 10.69 to 12.59 has been studied. Before any electrochemical measurements, evaluation of microstructure was obtained by optical microscope and transmission electron microscopy. To investigate the electrochemical behavior of the samples, the potentiodynamic polarization, Mott-Schottky analysis, and electrochemical impedance spectroscopy (EIS) were carried out. Potentiodynamic polarization plots and EIS measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure copper. Also, Mott-Schottky analysis indicated that the passive films behaved as p-type semiconductors and grain refinement did not change the semiconductor type of passive films.

Aggravation of cold-induced injury in Vero-B4 cells by RPMI 1640 medium - identification of the responsible medium components.

PubMed

Pless-Petig, Gesine; Metzenmacher, Martin; Türk, Tobias R; Rauen, Ursula

2012-10-10

In modern biotechnology, there is a need for pausing cell lines by cold storage to adapt large-scale cell cultures to the variable demand for their products. We compared various cell culture media/solutions for cold storage of Vero-B4 kidney cells, a cell line widely used in biotechnology. Cold storage in RPMI 1640 medium, a recommended cell culture medium for Vero-B4 cells, surprisingly, strongly enhanced cold-induced cell injury in these cells in comparison to cold storage in Krebs-Henseleit buffer or other cell culture media (DMEM, L-15 and M199). Manufacturer, batch, medium supplements and the most likely components with concentrations outside the range of the other media/solutions (vitamin B12, inositol, biotin, p-aminobenzoic acid) did not cause this aggravation of cold-induced injury in RPMI 1640. However, a modified Krebs-Henseleit buffer with a low calcium concentration (0.42 mM), a high concentration of inorganic phosphate (5.6 mM), and glucose (11.1 mM; i.e. concentrations as in RPMI 1640) evoked a cell injury and loss of metabolic function corresponding to that observed in RPMI 1640. Deferoxamine improved cell survival and preserved metabolic function in modified Krebs-Henseleit buffer as well as in RPMI 1640. Similar Ca2+ and phosphate concentrations did not increase cold-induced cell injury in the kidney cell line LLC-PK1, porcine aortic endothelial cells or rat hepatocytes. However, more extreme conditions (Ca2+ was nominally absent and phosphate concentration raised to 25 mM as in the organ preservation solution University of Wisconsin solution) also increased cold-induced injury in rat hepatocytes and porcine aortic endothelial cells. These data suggest that the combination of low calcium and high phosphate concentrations in the presence of glucose enhances cold-induced, iron-dependent injury drastically in Vero-B4 cells, and that a tendency for this pathomechanism also exists in other cell types.

Dominant oceanic bacteria secure phosphate using a large extracellular buffer

PubMed Central

Zubkov, Mikhail V.; Martin, Adrian P.; Hartmann, Manuela; Grob, Carolina; Scanlan, David J.

2015-01-01

The ubiquitous SAR11 and Prochlorococcus bacteria manage to maintain a sufficient supply of phosphate in phosphate-poor surface waters of the North Atlantic subtropical gyre. Furthermore, it seems that their phosphate uptake may counter-intuitively be lower in more productive tropical waters, as if their cellular demand for phosphate decreases there. By flow sorting 33P-phosphate-pulsed 32P-phosphate-chased cells, we demonstrate that both Prochlorococcus and SAR11 cells exploit an extracellular buffer of labile phosphate up to 5–40 times larger than the amount of phosphate required to replicate their chromosomes. Mathematical modelling is shown to support this conclusion. The fuller the buffer the slower the cellular uptake of phosphate, to the point that in phosphate-replete tropical waters, cells can saturate their buffer and their phosphate uptake becomes marginal. Hence, buffer stocking is a generic, growth-securing adaptation for SAR11 and Prochlorococcus bacteria, which lack internal reserves to reduce their dependency on bioavailable ambient phosphate. PMID:26198420

Phosphorus Amendment Efficacy for In Situ Remediation of Soil Lead Depends on the Bioaccessible Method.

PubMed

Obrycki, John F; Basta, Nicholas T; Scheckel, Kirk; Stevens, Brooke N; Minca, Kristen K

2016-01-01

A validated method is needed to measure reductions of in vitro bioaccessible (IVBA) Pb in urban soil remediated with amendments. This study evaluated the effect of in vitro extraction solution pH and glycine buffer on bioaccessible Pb in P-treated soils. Two Pb-contaminated soils (790-1300 mg Pb kg), one from a garden and one from a city lot in Cleveland, OH, were incubated in a bench scale experiment for 1 yr. Six phosphate amendments, including bone meal, fish bone, poultry litter, monoammonium phosphate, diammonium phosphate, and triple superphosphate, were added to containers at two application rates. Lead IVBA was assessed using USEPA Method 1340 and three modified versions of this method. Modifications included using solutions with pH 1.5 and 2.5 as well as using solutions with and without 0.4 mol L glycine. Soil amendments were ineffective in reducing IVBA Pb in these soils as measured by pH 1.5 with glycine buffer. The greatest reductions in IVBA Pb, from 5 to 26%, were found using pH 2.5 extractions. Lead mineral results showed several soil amendments promoted Pb phosphate formation, an indicator of remediation success. A significant negative linear relationship between reduction in IVBA Pb and Pb-phosphate formation was found only for pH 2.5 without glycine extraction solution. A modified USEPA Method 1340 without glycine and using pH 2.5 has the potential to predict P soil treatment efficacy and reductions in bioavailable Pb. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Apoenzyme of aspartate aminotransferase isozymes in serum and its diagnostic usefullness for hepatic diseases.

PubMed

Kamei, S; Ohkubo, A; Yamanaka, M

1979-08-15

Aspartate aminotransferase in the sera of normal subjects and of patients with hepatic diseases has been immunologically separated into two isoenzymes, cytosolic aspartate aminotransferase and mitochondrial aspartate aminotransferase. The activity of the isoenzymes was measured in three different buffer solutions with or without pyridoxal 5'-phosphate. To attain maximal activation, the apoenzyme of mitochondrial fraction must be preincubated with pyridoxal 5'-phosphate longer than that of the cytosolic fraction in either of the three reaction mixtures. In most sera the activity of both isoenzymes increased substantially in the presence of pyridoxal 5'-phosphate regardless of the type of buffer solutions. Both the apoenzymatic activity and the ratio of apo- to holo-enzymatic activity of each of the isoenzymes varied among samples from the patients with hepatic diseases. However, significantly high ratios of apo- to holo-enzymatic activity of both isoenzymes were observed in the patients with hepatoma in contrast with those with other hepatic diseases. These findings suggest that the simultaneous measurement of both apo- and holo-enzyme activities of aspartate aminotransferase isoenzymes may be useful in the clinical assessment of hepatic diseases.

Ocular toxicity of beta-blockers and benzalkonium chloride in pigmented rabbits: electrophysiological and morphological studies.

PubMed

Chou, A; Hori, S; Takase, M

1985-01-01

Subconjunctival injection of 0.2 ml of the following solutions was carried out once a day for two weeks in the albino and pigmented rabbit: commercial 0.5% timolol or 1% befunolol ophthalmic solutions, both containing benzalkonium chloride, and also these drug solutions containing no preservative, ophthalmic base solutions containing benzalkonium chloride, physiological saline solution or phosphate buffer solution. One week after daily injections of the commercial drug solutions or base solutions with benzalkonium chloride, the electroretinogram (ERG) showed a marked reduction in the a- and b-wave amplitudes in the pigmented rabbit, but the ERG changes were slight in the albino rabbit. After two weeks of injections, histological studies of the pigmented rabbit eyes revealed retinal detachment, visual cell loss and atrophy of the retinal pigment epithelium and choroid; the changes in the albino rabbit eyes were minimal. Injections of the beta-blockers containing no benzalkonium resulted in no significant changes in the ERG or in the tissue structures of all rabbits. Injections of only physiological saline or phosphate buffer had no deleterious effects. Therefore, the ocular toxicity of the beta-blockers was thought to be minor and the toxic effects seen in this study were thought to be due to benzalkonium chloride, which possibly accumulates in the ocular pigments.

Behavior of soluble and immobilized acid phosphatase in hydro-organic media.

PubMed

Wan, H; Horvath, C

1975-11-20

The hydrolysis of p-nitrophenyl phosphate by wheat germ acid phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.2) has been investigated in mixtures of aqueous buffers with acetone, dioxane and acetonitrile. The enzyme was either in free solution or immobilized on a pellicular support which consisted of a porous carbonaceous layer on solid glass beads. The highest enzyme activity was obtained in acetone and acetonitrile mixed with citrate buffer over a wide range of organic solvent concentration. In 50% (v/v) acetone both V and Km of the immobilized enzyme were about half of the values in the neat aqueous buffer, but the Ki for inorganic phosphate was unchanged. In 50% (v/v) mixtures of various solvents and citrate buffers of different pH, the enzymic activity was found to depend on the pH of the aqueous buffer component rather than the pH of the hydro-organic mixture as measured with the glass-calomel electrode. The relatively high rates of p-nitrophenol liberation in the presence of glucose even at high organic solvent concentrations suggest that transphosphorylation is facilitated at low water activity.

Mode changes associated with oil droplet movement in solutions of gemini cationic surfactants.

PubMed

Banno, Taisuke; Miura, Shingo; Kuroha, Rie; Toyota, Taro

2013-06-25

Micrometer-sized self-propelled oil droplets in nonequilibrium systems have attracted much attention, since they form stable emulsions composed of oil, water, and surfactant which represent a primitive type of inanimate chemical machinery. In this work, we examined means of controlling the movement of oil droplets by studying the dynamics of n-heptyloxybenzaldehyde droplets in phosphate buffers containing alkanediyl-α,ω-bis(N-dodecyl-N,N-dimethylammonium bromide) (nG12) with either tetramethylene (4G12), octaethylene (8G12), or dodecamethylene (12G12) chains in the linker moiety. Significant differences in droplet dynamics were observed to be induced by changes in the linker structure of these gemini cationic surfactants. In a phosphate buffer containing 30 mM 4G12, self-propelled motion of droplets concurrent with the formation of molecular aggregates on their surfaces was observed, whereas the fusion of oil droplets was evident in both 8G12 and 12G12 solutions. We also determined that the surface activities and the extent of molecular self-assembly of the surfactants in phosphate buffer were strongly influenced by the alkyl chain length in the linker moiety. We therefore conclude that the surface activities of the gemini cationic surfactant have important effects on the oil-water interfacial tension of oil droplets and the formation of molecular aggregates and that both of these factors induce the unique movement of the droplets.

Program on Resorbable Radio Devices

DTIC Science & Technology

2014-05-05

radio circuit - + PDMS Copper Mg PBS Buffer 1© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com Transient, Biocompatible...way, ZnO provides an alternative to silicon [ 16 ] or organic semi- conductors [ 17–20 ] for physically transient forms of electronics and sensors...immersion in several different types of solutions, such as phosphate buffer saline (PBS, pH 4.0, Sigma- Figure 1 . Materials and designs for

The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

USGS Publications Warehouse

Kramer, Henry

1956-01-01

A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

Pediatric oral solutions with propranolol hydrochloride for extemporaneous compounding: the formulation and stability study.

PubMed

Klovrzová, Sylva; Zahálka, Lukáš; Matysová, Ludmila; Horák, Petr; Sklubalová, Zdenka

2013-02-01

The aim of this study is to formulate an extemporaneous pediatric oral solution of propranolol hydrochloride (PRO) 2 mg/ml for the therapy of infantile haemangioma or hypertension in a target age group of 1 month to school children and to evaluate its stability. A citric acid solution and/or a citrate-phosphate buffer solution, respectively, were used as the vehicles to achieve pH value of about 3, optimal for the stability of PRO. In order to mask the bitter taste of PRO, simple syrup was used as the sweetener. All solutions were stored in tightly closed brown glass bottles at 5 ± 3 °C and/or 25 ± 3 °C, respectively. The validated HPLC method was used to evaluate the concentration of PRO and a preservative, sodium benzoate, at time intervals of 0-180 days. All preparations were stable at both storage temperatures with pH values in the range of 2.8-3.2. According to pharmacopoeial requirements, the efficacy of sodium benzoate 0.05 % w/v was proved (Ph.Eur., 5.1.3). The preparation formulated with the citrate-phosphate buffer, in our experience, had better palatability than that formulated with the citric acid solution. propranolol hydrochloride pediatric preparation extemporaneous preparation solution stability testing HPLC.

Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

NASA Astrophysics Data System (ADS)

Liu, Xiao-rong; Jiang, Sheng-cai; Liu, Yan-jun; Li, Hui; Wang, Hua-jun

2013-10-01

Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans ( A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30°C. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%-15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

The effect of the type of HA on the degradation of PLGA/HA composites.

PubMed

Naik, Ashutosh; Shepherd, David V; Shepherd, Jennifer H; Best, Serena M; Cameron, Ruth E

2017-01-01

The aim of this study is to explore the importance of the potentially competing effects of buffering effects of the calcium phosphate filler and particle-mediated water sorption on the degradation products of poly(d,l lactide-co-glycolide (50:50))(PLGA)/hydroxyapatite(HA) composites. Further the influence of type of HA on the mechanical properties of the composites was investigated. Phase pure HA was synthesised via a reaction between aqueous solutions of calcium hydroxide and orthophosphoric acid. The powder produced was either used as produced (uncalcined) or calcined in air or calcined in a humidified argon atmosphere. An in-vitro degradation study was carried out in phosphate buffered saline (PBS). The results obtained indicated that the degradation rate of the composite might be better understood if both the buffering effects and the rate of water sorption by the composites are considered. Copyright © 2016 Elsevier B.V. All rights reserved.

Coefficient of Friction of Human Corneal Tissue.

PubMed

Wilson, Tawnya; Aeschlimann, Rudolf; Tosatti, Samuele; Toubouti, Youssef; Kakkassery, Joseph; Osborn Lorenz, Katherine

2015-09-01

A novel property evaluation methodology was used to determine the elusive value for the human corneal coefficient of friction (CoF). Using a microtribometer on 28 fresh human donor corneas with intact epithelia, the CoF was determined in 4 test solutions (≥5 corneas/solution): tear-mimicking solution (TMS) in borate-buffered saline (TMS-PS), TMS in phosphate-buffered saline (TMS-PBS), TMS with HEPES-buffered saline (TMS-HEPES), and tear-like fluid in PBS (TLF-PBS). Mean (SD) CoF values ranged from 0.006 to 0.015 and were 0.013 (0.010) in TMS-PS, 0.006 (0.003) in TMS-PBS, 0.014 (0.005) in TMS-HEPES, and 0.015 (0.009) in TLF-PBS. Statistically significant differences were shown for TMS-PBS versus TLF (P = 0.0424) and TMS-PBS versus TMS-HEPES (P = 0.0179), but not for TMS-PBS versus TMS-PS (P = 0.2389). Successful measurement of the fresh human corneal tissue CoF was demonstrated, with values differing in the evaluated buffer solutions, within this limited sample size.

Pyrroloquinoline quinone (PQQ) is reduced to pyrroloquinoline quinol (PQQH2) by vitamin C, and PQQH2 produced is recycled to PQQ by air oxidation in buffer solution at pH 7.4.

PubMed

Mukai, Kazuo; Ouchi, Aya; Nagaoka, Shin-ichi; Nakano, Masahiko; Ikemoto, Kazuto

2016-01-01

Measurements of the reaction of sodium salt of pyrroloquinoline quinone (PQQNa2) with vitamin C (Vit C) were performed in phosphate-buffered solution (pH 7.4) at 25 °C under nitrogen atmosphere, using UV-vis spectrophotometry. The absorption spectrum of PQQNa2 decreased in intensity due to the reaction with Vit C and was changed to that of pyrroloquinoline quinol (PQQH2, a reduced form of PQQ). One molecule of PQQ was reduced by two molecules of Vit C producing a molecule of PQQH2 in the buffer solution. PQQH2, thus produced, was recycled to PQQ due to air oxidation. PQQ and Vit C coexist in many biological systems, such as vegetables, fruits, as well as in human tissues. The results obtained suggest that PQQ is reduced by Vit C and functions as an antioxidant in biological systems, because it has been reported that PQQH2 shows very high free-radical scavenging and singlet-oxygen quenching activities in buffer solutions.

Toward an In Vivo Dissolution Methodology: A Comparison of Phosphate and Bicarbonate Buffers

PubMed Central

Sheng, Jennifer J.; McNamara, Daniel P.; Amidon, Gordon L.

2011-01-01

Purpose To evaluate the difference between the pharmaceutical phosphate buffers and the gastrointestinal bicarbonates in dissolution of ketoprofen and indomethacin, to illustrate the dependence of buffer differential on biopharmaceutical properties of BCS II weak acids, and to recommend phosphate buffers equivalent to bicarbonates. Methods The intrinsic dissolution rates of, ketoprofen and indomethacin, were experimentally measured using rotating disk method at 37°C in USP SIF/FaSSIF and various concentrations of bicarbonates. Theoretical models including an improved reaction plane model and a film model were applied to estimate the surrogate phosphate buffers equivalent to the bicarbonates. Results Experimental results show that the intrinsic dissolution rates of ketoprofen and indomethacin, in USP and FaSSIF phosphate buffers are 1.5–3.0 times of that in the 15 mM bicarbonates. Theoretical analysis demonstrates that the buffer differential is largely dependent on the drug pKa and secondly on solubility, and weakly dependent on the drug diffusivity. Further, in accordance with the drug pKa, solubility and diffusivity, simple phosphate surrogate was proposed to match an average bicarbonate value (15 mM) of the upper gastrointestinal region. Specifically, phosphate buffers of 13–15 mM and 3–4 mM were recommended for ketoprofen and indomethacin, respectively. For both ketoprofen and indomethacin, the intrinsic dissolution using the phosphate surrogate buffers closely approximated the 15 mM bicarbonate buffer. Conclusions This work demonstrates the substantial difference between pharmaceutical phosphates and physiological bicarbonates in determining the drug intrinsic dissolution rates of BCS II weak acids, such as ketoprofen and indomethacin. Surrogate phosphates were recommended in order to closely reflect the in vivo dissolution of ketoprofen and indomethacin in gastrointestinal bicarbonates, which has significant implications for defining buffer systems for BCS II weak acids in developing in vitro bioequivalence dissolution methodology. PMID:19183104

Spontaneous interfacial reaction between metallic copper and PBS to form cupric phosphate nanoflower and its enzyme hybrid with enhanced activity.

PubMed

He, Guangli; Hu, Weihua; Li, Chang Ming

2015-11-01

We herein report the spontaneous interfacial reaction between copper foil with 0.01 M phosphate buffered saline (PBS) to form free-standing cupric phosphate (Cu3(PO4)2) nanoflowers at ambient temperature. The underlying chemistry was thoroughly investigated and it is found that the formation of nanoflower is synergistically caused by dissolved oxygen, chlorine ions and phosphate ions. Enzyme-Cu3(PO4)2 hybrid nanoflower was further prepared successfully by using an enzyme-dissolving PBS solution and the enzymes in the hybrid exhibit enhanced biological activity. This work provides a facile route for large-scale synthesis of hierarchical inorganic and functional protein-inorganic hybrid architectures via a simple one-step solution-immersion reaction without using either template or surfactant, thus offering great potential for biosensing application among others. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of coating layer and release medium on release profile from coated capsules with Eudragit FS 30D: an in vitro and in vivo study.

PubMed

Moghimipour, Eskandar; Rezaei, Mohsen; Kouchak, Maryam; Fatahiasl, Jafar; Angali, Kambiz Ahmadi; Ramezani, Zahra; Amini, Mohsen; Dorkoosh, Farid Abedin; Handali, Somayeh

2018-05-01

The aim of the present research was to evaluate the impact of coating layers on release profile from enteric coated dosage forms. Capsules were coated with Eudragit FS 30D using dipping method. The drug profile was evaluated in both phosphate buffer and Hank's solutions. Utilization X-ray imaging, gastrointestinal transmission of enteric coated capsules was traced in rats. According to the results, no release of the drug was found at pH 1.2, and the extent of release drug in pH 6.8 medium was decreased by adding the coating layers. The results indicated single-layer coated capsules in phosphate buffer were significantly higher than that in Hank's solution. However, no significant difference was observed from capsules with three coating layers in two different dissolution media. X-ray imaging showed that enteric coated capsules were intact in the stomach and in the small intestine, while disintegrated in the colon.

Optimization of protein solution by a novel experimental design method using thermodynamic properties.

PubMed

Kim, Nam Ah; An, In Bok; Lee, Sang Yeol; Park, Eun-Seok; Jeong, Seong Hoon

2012-09-01

In this study, the structural stability of hen egg white lysozyme in solution at various pH levels and in different types of buffers, including acetate, phosphate, histidine, and Tris, was investigated by means of differential scanning calorimetry (DSC). Reasonable pH values were selected from the buffer ranges and were analyzed statistically through design of experiment (DoE). Four factors were used to characterize the thermograms: calorimetric enthalpy (ΔH), temperature at maximum heat flux (T( m )), van't Hoff enthalpy (ΔH( V )), and apparent activation energy of protein solution (E(app)). It was possible to calculate E(app) through mathematical elaboration from the Lumry-Eyring model by changing the scan rate. The transition temperature of protein solution, T( m ), increased when the scan rate was faster. When comparing the T( m ), ΔH( V ), ΔH, and E(app) of lysozyme in various pH ranges and buffers with different priorities, lysozyme in acetate buffer at pH 4.767 (scenario 9) to pH 4.969 (scenario 11) exhibited the highest thermodynamic stability. Through this experiment, we found a significant difference in the thermal stability of lysozyme in various pH ranges and buffers and also a new approach to investigate the physical stability of protein by DoE.

[High performance liquid chromatogram (HPLC) determination of adenosine phosphates in rat myocardium].

PubMed

Miao, Yu; Wang, Cheng-long; Yin, Hui-jun; Shi, Da-zhuo; Chen, Ke-ji

2005-04-18

To establish method for the quantitative determination of adenosine phosphates in rat myocardium by optimized high performance liquid chromatogram (HPLC). ODS HYPERSIL C(18) column and a mobile phase of 50 mmol/L tribasic potassium phosphate buffer solution (pH 6.5), with UV detector at 254 nm were used. The average recovery rates of myocardial adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were 99%-107%, 96%-104% and 95%-119%, respectively; relative standard deviations (RSDs) of within-day and between-days were less than 1.5% and 5.1%, respectively. The method is simple, rapid and accurate, and can be used to analyse the adenosine phosphates in myocardium.

Biological Degradation of Tetrachloroethylene in Methanogenic Conditions

DTIC Science & Technology

1994-06-01

stock of neat PCE was not purged with N2-C0 2. Alcohol oxidase (from Pichia pasrori, phosphate-buffered 60 percent sucrose solution), peroxidase (Type...dechlorination of tetrachlorocthene in anaerobic aquifer microcosms by addition of short-chain organic acids or alcohols ," Appl. Environ. Microbiol. (58

The effect of reaction conditions on formation of wet precipitated calcium phosphates

NASA Astrophysics Data System (ADS)

Huang, Chen; Cao, Peng

2015-03-01

The precipitation process discussed in the present study involves the addition of alkaline solutions to an acidic calcium phosphate suspension. Several parameters (pH, pH buffer reagent, ageing and stirring) were investigated. The synthesized powders were calcined at 1000°C for 1 h in air, in order to study the thermal stability and crystalline phase compositions. X-ray diffraction (XRD) and ESEM analysis were used for sample characterization. It is found that all these processing parameters affect the crystalline phases evolved and resultant microstructures. Phase evolution occurred at an elevated pH level. The pH buffer reagent would affect both the phase composition and microstructure. Ageing was essential for the phase maturation. Stirring accelerated the reaction process by providing a homogeneous medium for precipitation.

Degradation of bare and silanized silicon wafer surfaces by constituents of biological fluids.

PubMed

Dekeyser, C M; Buron, C C; Derclaye, S R; Jonas, A M; Marchand-Brynaert, J; Rouxhet, P G

2012-07-15

The 24 h stability of bare silicon wafers as such or silanized with CH(3)O-(CH(2)-CH(2)-O)(n)-C(3)H(6)-trichlorosilane (n=6-9) was investigated in water, NaCl, phosphate and carbonate solutions, and in phosphate buffered saline (PBS) at 37 °C (close to biological conditions regarding temperature, high ionic strength, and pH). The resulting surfaces were analyzed using ellipsometry, X-ray Reflectometry (XRR), X-ray Photoelectron Spectroscopy (XPS), and Atomic Force Microscopy (AFM). Incubation of the silanized wafers in phosphate solution and PBS provokes a detachment of the silane layer. This is due to a hydrolysis of Si-O bonds which is favored by the action of phosphate, also responsible for a corrosion of non-silanized wafers. The surface alteration (detachment of silane layer and corrosion of the non-silanized wafer) is also important with carbonate solution, due to a higher pH (8.3). The protection of the silicon oxide layer brought by silane against the action of the salts is noticeable for phosphate but not for carbonate. Copyright © 2012 Elsevier Inc. All rights reserved.

Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

PubMed

Vargas-Barbosa, Nella M; Geise, Geoffrey M; Hickner, Michael A; Mallouk, Thomas E

2014-11-01

Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

RELATIVE RATE CONSTANTS OF CONTAMINANT CANDIDATE LIST PESTICIDES WITH HYDROXYL RADICALS

EPA Science Inventory

The objective of this study was to establish the rate constants for the reactions of selected pesticides listed on the US EPA Contaminant Candidate List, with UV and hydroxyl radicals (·OH). Batch experiments were conducted in phosphate buffered solution at pH 7. All pestici...

Use of bicarbonate buffer systems for dissolution characterization of enteric-coated proton pump inhibitor tablets.

PubMed

Shibata, Hiroko; Yoshida, Hiroyuki; Izutsu, Ken-Ichi; Goda, Yukihiro

2016-04-01

The aim of this study was to assess the effects of buffer systems (bicarbonate or phosphate at different concentrations) on the in vitro dissolution profiles of commercially available enteric-coated tablets. In vitro dissolution tests were conducted using an USP apparatus II on 12 enteric-coated omeprazole and rabeprazole tablets, including innovator and generic formulations in phosphate buffers, bicarbonate buffers and a media modified Hanks (mHanks) buffer. Both omeprazole and rabeprazole tablets showed similar dissolution profiles among products in the compendial phosphate buffer system. However, there were large differences between products in dissolution lag time in mHanks buffer and bicarbonate buffers. All formulations showed longer dissolution lag times at lower concentrations of bicarbonate or phosphate buffers. The dissolution rank order of each formulation differed between mHanks buffer and bicarbonate buffers. A rabeprazole formulation coated with a methacrylic acid copolymer showed the shortest lag time in the high concentration bicarbonate buffer, suggesting varied responses depending on the coating layer and buffer components. Use of multiple dissolution media during in vitro testing, including high concentration bicarbonate buffer, would contribute to the efficient design of enteric-coated drug formulations. © 2016 Royal Pharmaceutical Society, Journal of Pharmacy and Pharmacology.

Phosphate and HEPES buffers potently affect the fibrillation and oligomerization mechanism of Alzheimer's A{beta} peptide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garvey, Megan; Tepper, Katharina; Haupt, Caroline

Highlights: {yields} Sodium phosphate buffer accelerated A{beta}(1-40) nucleation relative to HEPES. {yields} A{beta}(1-40) fibrils formed in the two buffers show only minor structural differences. {yields} NMR revealed that A{beta}(1-40) histidine residues mediate buffer dependent changes. -- Abstract: The oligomerization of A{beta} peptide into amyloid fibrils is a hallmark of Alzheimer's disease. Due to its biological relevance, phosphate is the most commonly used buffer system for studying the formation of A{beta} and other amyloid fibrils. Investigation into the characteristics and formation of amyloid fibrils frequently relies upon material formed in vitro, predominantly in phosphate buffers. Herein, we examine the effects onmore » the fibrillation and oligomerization mechanism of A{beta} peptide that occur due solely to the influence of phosphate buffer. We reveal that significant differences in amyloid fibrillation are observed due to fibrillation being initiated in phosphate or HEPES buffer (at physiological pH and temperature). Except for the differing buffer ions, all experimental parameters were kept constant. Fibril formation was assessed using fluorescently monitored kinetic studies, microscopy, X-ray fiber diffraction and infrared and nuclear magnetic resonance spectroscopies. Based on this set up, we herein reveal profound effects on the mechanism and speed of A{beta} fibrillation. The three histidine residues at positions 6, 13 and 14 of A{beta}(1-40) are instrumental in these mechanistic changes. We conclude that buffer plays a more significant role in fibril formation than has been generally acknowledged.« less

Stability study of the anticonvulsant enaminone (E118) using HPLC and LC-MS.

PubMed

Abdel-Hamid, Mohammed E; Edafiogho, Ivan O; Hamza, Huda M

2002-01-01

The stability of the new chemical synthetic enaminone derivative (E118) was investigated using a stability-indicating high-performance liquid chromatography (HPLC) procedure. The examined samples were analyzed using a chiral HSA column and a mobile phase (pH 7.5) containing n-octanoic acid (5 mM), isopropyl alcohol and 100 mM disodium hydrogen phosphate solution (1:9 v/v) at a flow rate of 1 ml min(-1). The developed method was specific, accurate and reproducible. The HPLC chromatograms exhibited well-resolved peaks of E118 and the degradation products at retention times <5 min. The stability of E118 was performed in 0.1 M hydrochloric acid, 0.1 M sodium hydroxide, water/ethanol (1:1) and phosphate buffer (pH approximately 7.5) solutions. E118 was found to undergo fast hydrolysis in 0.1 M hydrochloric acid solution. The decomposition of E118 followed first order kinetics under the experimental conditions. The results confirmed that protonation of the enaminone system in the molecule enhanced the hydrolysis of E118 at degradation rate constant of 0.049 min(-1) and degradation half-life of 14.1 min at 25 degrees C. However, E118 was significantly stable in 0.1 M sodium hydroxide, physiological phosphate buffer (pH 7.5) and ethanol/water (1:1) solutions. The degradation rate constants and degradation half-lives were in the ranges 0.0023-0.0086 h(-1) and 80.6-150.6 h, respectively. Analysis of the acid-induced degraded solution of E118 by liquid chromatography-mass spectrometry (LC-MS) revealed at least two degradation products of E118 at m/z 213.1 and 113.1, respectively.

Additive solution-7 reduces the red blood cell cold storage lesion.

PubMed

Cancelas, Jose A; Dumont, Larry J; Maes, Lou A; Rugg, Neeta; Herschel, Louise; Whitley, Pamela H; Szczepiokowski, Zbigniew M; Siegel, Alan H; Hess, John R; Zia, Majid

2015-03-01

Transfusion of long-stored red blood cells (RBCs) is associated with decreased in vivo RBC recovery, delivery of RBC breakdown products, and increased morbidity and mortality. Reducing the burden of this RBC "storage lesion" is a major challenge in transfusion medicine. Additive solution-7 (AS-7) is a new RBC storage solution designed to improve RBC metabolism by providing phosphate and increasing buffering capacity. Storage quality in AS-7 was measured in a prospective, randomized, three-center trial using units of whole blood from healthy human subjects whose RBCs were stored for up to 56 days in AS-7 (n = 120) or for 42 days in the control solution AS-1 (n = 60). Hemolysis and shedding of protein-containing microvesicles were significantly reduced in RBCs stored in AS-7 for 42 and 56 days compared with RBCs stored in AS-1. Autologous in vivo recoveries of RBCs stored in AS-7 was 88 ± 5% at 42 days (n = 27) and 82 ± 3% at 56 days (n = 27), exceeding recoveries of RBCs stored in currently used solutions. Increasing the phosphate, pH range, and buffer capacity of a RBC storage system allowed RBCs to be stored better and longer than currently approved storage systems. AS-7 ameliorates the long-term storage lesion resulting in significantly increased viability in vitro and in vivo. © 2014 AABB.

A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material.

PubMed

Wen, Zhaohui; Zhang, Liming; Chen, Chao; Liu, Yibo; Wu, Changjun; Dai, Changsong

2013-04-01

Slow corrosion rate and poor bioactivity restrict iron-based implants in biomedical application. In this study, we design a new iron-foam-based calcium phosphate/chitosan coating biodegradable composites offering a priority mechanical and bioactive property for bone tissue engineering through electrophoretic deposition (EPD) followed by a conversion process into a phosphate buffer solution (PBS). Tensile test results showed that the mechanical property of iron foam could be regulated through altering the construction of polyurethane foam. The priority coatings were deposited from 40% nano hydroxyapatite (nHA)/ethanol suspension mixed with 60% nHA/chitosan-acetic acid aqueous solution. In vitro immersion test showed that oxidation-iron foam as the matrix decreased the amount of iron implanted and had not influence on the bioactivity of this implant, obviously. So, this method could also be a promising method for the preparation of a new calcium phosphate/chitosan coating on foam construction. Copyright © 2012. Published by Elsevier B.V.

Formation of Fluorohydroxyapatite with Silver Diamine Fluoride

PubMed Central

Mei, M.L.; Nudelman, F.; Marzec, B.; Walker, J.M.; Lo, E.C.M.; Walls, A.W.; Chu, C.H.

2017-01-01

Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared—calcium phosphate (CaCl2·2H2O + K2HPO4 in buffer solution) and SDF (Ag[NH3]2F in buffer solution). After incubation at 37 oC for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with reduced solubility could be one of the main factors for arrest of caries lesions treated with SDF. PMID:28521107

Inactivation of Hepatitis A Virus (HAV) by Chlorine and Iodine in Water

DTIC Science & Technology

1986-11-01

treatment practices utilizing chemical disinfection, primarily chlorination, are generally believed to * be effective in producing microbiologically safe...OCl) in 1 liter of HDFW. Stock solution was then diluted in tesi water (halogen demand-free, 0.01M phosphate buffer, pH 4.5, 7.0 or 9.5 in initial

EFFECTS OF PH ON DECHLORINATION OF TRICHLOROETHYLENE BY ZERO-VALENT IRON

EPA Science Inventory

The reduction rates of trichloroethylene (TCE) using zero-valent iron (ZVI) and the rates of iron hydrolysis were characterized at pH values of 5 to 10. The reduction of TCE by ZVI was carried out in batch reactors filled with pH-buffered (phosphate based) solutions under anaerob...

Discernment of lint trash in raw cotton using multivariate analysis of excitation-emission luminescence spectra

USDA-ARS?s Scientific Manuscript database

Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component An...

Corrosion behavior of pristine and added MgB2 in Phosphate Buffered Saline Solution

NASA Astrophysics Data System (ADS)

Batalu, D.; Bojin, D.; Ghiban, B.; Aldica, G.; Badica, P.

2012-09-01

We have obtained by Spark Plasma Sintering (SPS), dense samples of MgB2 added with Ho2O3. Starting composition was (MgB2)0.975(HoO1.5)0.025 and we used addition powders with an average particle size below and above 100 nm. For Mg, pristine and added MgB2 samples we measured potentiodynamic polarization curves in Phosphate Buffered Saline (PBS) solution media at room temperature. MgB2 based composites show corrosion/ degradation effects. This behavior is in principle similar to Mg based alloys in the same media. Our work suggests that the different morphologies and phase compositions of the SPS-ed samples influence the interaction with corrosion medium; hence additions can play an important role in controlling the corrosion rate. Pristine MgB2 show a significant improvement of the corrosion resistance, if compared with Mg. The best corrosion resistance is obtained for pristine MgB2, followed by MgB2 with nano-Ho2O3 and μ-Ho2O3 additions.

Overloaded elution band profiles of ionizable compounds in reversed-phase liquid chromatography: Influence of the competition between the neutral and the ionic species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A

2008-01-01

The parameters that affect the shape of the band profiles of acido-basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pK{sub a} are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 {micro}L) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C{sub 18}-bonded packing materials, including the 5more » {micro}m Xterra-C{sub 18} (121 {angstrom}), 5 {micro}m Gemini-C{sub 18} (110 {angstrom}), 5 {micro}m Luna-C{sub 18}(2) (93 {angstrom}), 3.5 {micro}m Extend-C{sub 18} (80 {angstrom}), and 2.7 {micro}m Halo-C{sub 18} (90 {angstrom}). The mobile phase was an aqueous solution of methanol buffered at a constant {sub W}{sup W}pH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3-phenyl 1-propanol, 2-phenyl butyric acid, amphetamine, aniline, benzylamine, p-toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pK{sub a} and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution.« less

Chemical Modification of the Olfactory Receptor Epithelium of Vertebrate Species

DTIC Science & Technology

1990-06-28

Pre-column Derivatization Procedure: 1.0 mL of the Jeffamine solution was mixed with 1.0 mL of NaCN, 5.0 mL of phosphate buffer pH 9.5 followed by 1.0...running buffer. All the unprotonated components elute at the same time because their rate of elution is controlled only by the rate of electroosmotic ...elecarosomotic mobility under our experimental conditions. Using an average elution time of 22.2 min the measured electroosmotic mobility is 1.3 x 10-4 cm2

Multiprobe Spectroscopic Inverstigation of Molecular-level Behavior within Aqueous 1-Butyl-3-methylimidazolium Tetrafluoroborate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Abhra; Ali, Maroof; Baker, Gary A

2009-01-01

In this work, an array of molecular-level solvent featuressincluding solute-solvent/solvent-solvent interactions, dipolarity, heterogeneity, dynamics, probe accessibility, and diffusionswere investigated across the entire composition of ambient mixtures containing the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4], and pH 7.0 phosphate buffer, based on results assembled for nine different molecular probes utilized in a range of spectroscopic modes. These studies uncovered interesting and unusual solvatochromic probe behavior within this benchmark mixture. Solvatochromic absorbance probessa watersoluble betaine dye (betaine dye 33), N,N-diethyl-4-nitroaniline, and 4-nitroanilineswere employed to determine ET (a blend of dipolarity/polarizability and hydrogen bond donor contributions) and the Kamlet-Taft indices * (dipolarity/polarizability), R (hydrogenmore » bond donor acidity), and (hydrogen bond acceptor basicity) characterizing the [bmim][BF4] + phosphate buffer system. These parameters each showed a marked deviation from ideality, suggesting selective solvation of the individual probe solutes by [bmim][BF4]. Similar conclusions were derived from the responses of the fluorescent polarity-sensitive probes pyrene and pyrene-1-carboxaldehyde. Importantly, the fluorescent microfluidity probe 1,3-bis(1-pyrenyl)propane senses a microviscosity within the mixture that significantly exceeds expectations derived from simple interpolation of the behavior in the neat solvents. On the basis of results from this probe, a correlation between microviscosity and bulk viscosity was established; pronounced solvent-solvent hydrogen-bonding interactions were implicit in this behavior. The greatest deviation from ideal additive behavior for the probes studied herein was consistently observed to occur in the buffer-rich regime. Nitromethane-based fluorescence quenching of pyrene within the [bmim][BF4] + phosphate buffer system showed unusual compliance with a sphere-of-action quenching model, a further manifestation of the microheterogeneity of the system. Fluorescence correlation spectroscopic results for both small (BODIPY FL) and macromolecular (Texas Red-10 kDa dextran conjugate) diffusional probes provide additional evidence in support of microphase segregation inherent to aqueous [bmim][BF4].« less

Evaluation of the pH- and Thermal Stability of the Recombinant Green Fluorescent Protein (GFP) in the Presence of Sodium Chloride

NASA Astrophysics Data System (ADS)

Ishii, Marina; Kunimura, Juliana Sayuri; Jeng, Hélio Tallon; Vessoni Penna, Thereza Christina; Cholewa, Olivia

The thermal stability of recombinant green fluorescent protein (GFP) in sodium chloride (NaCl) solutions at different concentrations, pH, and temperatures was evaluated by assaying the loss of fluorescence intensity as a measure of denaturation. GFP, extracted from Escherichia coli cells by the three-phase partitioning method and purified through a butyl hydrophobic interaction chromatography (HIC) column, was diluted in water for injection (WFI) (pH 6.0-7.0) and in 10 mM buffer solutions (acetate, pH 5.0; phosphate, pH 7.0; and Tris-EDTA, pH 8.0) with 0.9-30% NaCl or without and incubated at 80-95°C. The extent of protein denaturation was expressed as a percentage of the calculated decimal reduction time (D-value). In acetate buffer (pH 4.84 ±0.12), the mean D-values for 90% reduction in GFP fluorescence ranged from 2.3 to 3.6 min, independent of NaCl concentration and temperature. GFP thermal stability diluted in WFI (pH 5.94±0.60) was half that observed in phosphate buffer (pH 6.08±0.60); but in both systems, D-values decreased linearly with increasing NaCl concentration, with D-values (at 80°C) ranging from 3.44, min (WFI) to 6.1 min (phosphate buffer), both with 30% NaCl. However, D-values in Tris-EDTA (pH 7.65±0.17) were directly dependent on the NaCl concentration and 5-10 times higher than D-values for GFP in WFI at 80°C. GFP pH-and thermal stability can be easily monitored by the convenient measure of fluorescence intensity and potentially be used as an indicator to monitor that processing times and temperatures were attained.

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China

NASA Astrophysics Data System (ADS)

Li, M.; Whelan, M. J.; Wang, G.; White, S. M.

2012-12-01

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO4 from Ca2+ and HPO42- when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC0) vary from 0.014 mg l-1 to 0.061 mg l-1, which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC0 and linear sorption coefficients (K) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China

NASA Astrophysics Data System (ADS)

Li, M.; Whelan, M. J.; Wang, G. Q.; White, S. M.

2013-05-01

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus (P) behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO4 from Ca2+ and HPO42- when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC0) vary from 0.014 mg L-1 to 0.061 mg L-1, which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC0 and linear sorption coefficients (K) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

BIOKID: Randomized controlled trial comparing bicarbonate and lactate buffer in biocompatible peritoneal dialysis solutions in children [ISRCTN81137991

PubMed Central

Nau, Barbara; Schmitt, Claus P; Almeida, Margarida; Arbeiter, Klaus; Ardissino, Gianluigi; Bonzel, Klaus E; Edefonti, Alberto; Fischbach, Michel; Haluany, Karin; Misselwitz, Joachim; Kemper, Markus J; Rönnholm, Kai; Wygoda, Simone; Schaefer, Franz

2004-01-01

Background Peritoneal dialysis (PD) is the preferred dialysis modality in children. Its major drawback is the limited technique survival due to infections and progressive ultrafiltration failure. Conventional PD solutions exert marked acute and chronic toxicity to local tissues. Prolonged exposure is associated with severe histopathological alterations including vasculopathy, neoangiogenesis, submesothelial fibrosis and a gradual loss of the mesothelial cell layer. Recently, more biocompatible PD solutions containing reduced amounts of toxic glucose degradation products (GDPs) and buffered at neutral pH have been introduced into clinical practice. These solutions contain lactate, bicarbonate or a combination of both as buffer substance. Increasing evidence from clinical trials in adults and children suggests that the new PD fluids may allow for better long-term preservation of peritoneal morphology and function. However, the relative importance of the buffer in neutral-pH, low-GDP fluids is still unclear. In vitro, lactate is cytotoxic and vasoactive at the concentrations used in PD fluids. The BIOKID trial is designed to clarify the clinical significance of the buffer choice in biocompatible PD fluids. Methods/design The objective of the study is to test the hypothesis that bicarbonate based PD solutions may allow for a better preservation of peritoneal transport characteristics in children than solutions containing lactate buffer. Secondary objectives are to assess any impact of the buffer system on acid-base status, peritoneal tissue integrity and the incidence and severity of peritonitis. After a run-in period of 2 months during which a targeted cohort of 60 patients is treated with a conventional, lactate buffered, acidic, GDP containing PD fluid, patients will be stratified according to residual renal function and type of phosphate binding medication and randomized to receive either the lactate-containing Balance solution or the bicarbonate-buffered Bicavera® solution for a period of 10 months. Patients will be monitored by monthly physical and laboratory examinations. Peritoneal equilibration tests, 24-h dialysate and urine collections will be performed 4 times. Peritoneal biopsies will be obtained on occasion of intraabdominal surgery. Changes in small solute transport rates, markers of peritoneal tissue turnover in the effluent, acid-base status and peritonitis rates and severity will be analyzed. PMID:15485574

Intercalation and controlled release of 2,4-dichlorophenoxyacetic acid using rhombohedral [LiAl2(OH)6]Cl·xH2O

NASA Astrophysics Data System (ADS)

Ragavan, Anusha; Khan, Aamir I.; O'Hare, Dermot

2006-05-01

2,4-Dichlorophenoxyacetic acid (2,4-D) has been fully intercalated into the rhombohedral polymorph of [LiAl2(OH)6]Cl·xH2O ([rhom-Li Al] LDH) by an ion exchange method. The controlled release of 2,4-D from the interlamellar spaces of [rhom-Li Al] LDH has been studied in a phosphate buffer, natural rainwater and deionised water. In buffer solution and rainwater, the intercalated herbicide is exchanged for anions in solution. In contrast, in deionised water the herbicide is released as part of the Li+/herbicide ion pair, leading to the formation of Al(OH)3 and the solvated ions.

Effects of buffer composition and processing conditions on aggregation of bovine IgG during freeze-drying.

PubMed

Sarciaux, J M; Mansour, S; Hageman, M J; Nail, S L

1999-12-01

The objective of this study was to identify critical formulation and processing variables affecting aggregation of bovine IgG during freeze-drying when no lyoprotective solute is used. Parameters examined were phosphate buffer concentration and counterion (Na versus K phosphate), added salts, cooling rate, IgG concentration, residual moisture level, and presence of a surfactant. No soluble aggregates were detected in any formulation after either freezing/thawing or freeze-drying. No insoluble aggregates were detected in any formulation after freezing, but insoluble aggregate levels were always detectable after freeze-drying. The data are consistent with a mechanism of aggregate formation involving denaturation of IgG at the ice/freeze-concentrate interface which is reversible upon freeze-thawing, but becomes irreversible after freeze-drying and reconstitution. Rapid cooling (by quenching in liquid nitrogen) results in more and larger aggregates than slow cooling on the shelf of the freeze-dryer. This observation is consistent with surface area measurements and environmental electron microscopic data showing a higher surface area of freeze-dried solids after fast cooling. Annealing of rapidly cooled solutions results in significantly less aggregation in reconstituted freeze-dried solids than in nonannealed controls, with a corresponding decrease in specific surface area of the freeze-dried, annealed system. Increasing the concentration of IgG significantly improves the stability of IgG against freeze-drying-induced aggregation, which may be explained by a smaller percentage of the protein residing at the ice/freeze-concentrate interface as IgG concentration is increased. A sodium phosphate buffer system consistently results in more turbid reconstituted solids than a potassium phosphate buffer system at the same concentration, but this effect is not attributable to a pH shift during freezing. Added salts such as NaCl or KCl contribute markedly to insoluble aggregate formation. Both sodium and potassium chloride contribute more to turbidity of the reconstituted solid than either sodium or potassium phosphate buffers at similar ionic strength, with sodium chloride resulting in a substantially higher level of aggregates than potassium chloride. At a given cooling rate, the specific surface area of dried solids is approximately a factor of 2 higher for the formulation containing sodium chloride than the formulation containing potassium chloride. Turbidity is also influenced by the extent of secondary drying, which underscores the importance of minimizing secondary drying of this system. Including a surfactant such as polysorbate 80, either in the formulation or in the water used for reconstitution, decreased, but did not eliminate, insoluble aggregates. There was no correlation between pharmaceutically acceptability of the freeze-dried cake and insoluble aggregate levels in the reconstituted product.

Buffer capacity of biologics--from buffer salts to buffering by antibodies.

PubMed

Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

2013-01-01

Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ΔI=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. Copyright © 2013 American Institute of Chemical Engineers.

USSR and Eastern Europe Scientific Abstracts, Biomedical and Behavioral Sciences, Number 68

DTIC Science & Technology

1977-04-13

different protein fractions. In addition, the kinetics of the effect of a permanent magnetic field on solutions of bovine serum albumin was...virus with Earle’s solution, pH 8.2, Hottinger’s bouillon with 10% bovine serum pH 8.4 or 0.5 M phosphate buffer pH 8.2; and virological examination of...hepatitis, nephritis, mastitis et lymphonodulitis lymphonodulorum supramammarium, hyperplasia substantiae lymphoreticularis of the spleen and other lymph

Time-related Changes in pH, Buffering Capacity and Phosphate and Urea Concentration of Stimulated Saliva.

PubMed

Vuletic, Lea; Peros, Kristina; Spalj, Stjepan; Rogic, Dunja; Alajbeg, Ivan

2014-01-01

To quantify changes in pH, buffering capacity and hydrogen carbonate, phosphate, protein and urea concentrations of stimulated saliva which occur during a 30-min measurement delay after saliva collection. The correlation between time-related chemical changes and changes of salivary pH and buffering capacity was assessed in order to explain the observed changes in salivary pH and buffering capacity. Stimulated saliva samples were collected from 30 volunteers after inducing salivation by chewing a piece of parafilm. Measurements of salivary variables were made immediately after saliva collection and again 30 min later, during which time the specimens were exposed to the atmosphere in collection cups at room temperature. Postponement of measurements resulted in a significant increase in pH and a significant decrease of buffering capacity, phosphate and urea concentration. The results suggest that the time-related pH increase could primarily be attributed to loss of dissolved carbon dioxide from saliva, and confirm the importance of hydrogen carbonate in the neutralisation of hydrogen ions, but they do not support the principle of catalysed phase-buffering for the hydrogen carbonate buffer system in saliva. A decrease in phosphate and urea concentration affects salivary buffering capacity. This study emphasises the importance of the standardisation of measurement time when measuring salivary pH, buffering capacity, phosphate and urea concentrations following the collection of saliva in order to obtain comparable results. It also provides a partial explanation of the mechanisms underlying the observed changes of pH and buffering capacity over time.

Monitoring of interstitial buffer systems using micro-dialysis and infrared spectrometry

NASA Astrophysics Data System (ADS)

Heise, H. M.; Cocchieri, L.; Vahlsing, T.; Ihrig, D.; Elm, J.

2017-02-01

Nowadays, continuous sensing systems are important point-of-care devices for the hospital and personalized patient technology. FTIR-spectrometers have been successfully employed for the development of bed-side systems. In-vivo applications for critically ill patients can be envisaged for analytes and parameters, which are of interest for intensive care such as lactate, urea, pCO2 and pH. The human body maintains the blood pH around 7.4, but for severe pH level changes acidosis or alkalosis can lead to serious health problems. Three different buffer systems exist based on bicarbonate, phosphate and proteins; for the most important bicarbonate and phosphate systems infrared transmission spectra were recorded. By using the CO2 and HCO3 - bands of the bicarbonate spectra, the pH of the harvested biofluid can be predicted using the Henderson-Hasselbalch equation. Furthermore, we studied the solubility of CO2 in aqueous solutions using gas mixtures of N2 and CO2 with known composition within partial pressures of CO2 as relevant for invivo conditions. Thus, values of pCO2 up to 150 mm Hg (200 hPa) with distilled water and a Ringer solution, which is an isotonic electrolyte solution used for medical infusion, were measured at 25 °C and 37 °C (normal body temperature).

Flexible, Low-Cost Sensor Based on Electrolyte Gated Carbon Nanotube Field Effect Transistor for Organo-Phosphate Detection

PubMed Central

Bhatt, Vijay Deep; Joshi, Saumya; Becherer, Markus; Lugli, Paolo

2017-01-01

A flexible enzymatic acetylcholinesterase biosensor based on an electrolyte-gated carbon nanotube field effect transistor is demonstrated. The enzyme immobilization is done on a planar gold gate electrode using 3-mercapto propionic acid as the linker molecule. The sensor showed good sensing capability as a sensor for the neurotransmitter acetylcholine, with a sensitivity of 5.7 μA/decade, and demonstrated excellent specificity when tested against interfering analytes present in the body. As the flexible sensor is supposed to suffer mechanical deformations, the endurance of the sensor was measured by putting it under extensive mechanical stress. The enzymatic activity was inhibited by more than 70% when the phosphate-buffered saline (PBS) buffer was spiked with 5 mg/mL malathion (an organophosphate) solution. The biosensor was successfully challenged with tap water and strawberry juice, demonstrating its usefulness as an analytical tool for organophosphate detection. PMID:28524071

Microwave fixation versus formalin fixation of surgical and autopsy tissue.

PubMed

Login, G R

1978-05-01

Microwave irradiation of surgical and autopsy tissue penetrates, fixes, and hardens the tissue almost immediately (the fluid media used in the microwave consisted of saline, ten percent phosphate buffered formalin, and distilled water). Tissue sections from a representative sample of organs were tested. Comparable sections were simultaneously fixed in a phosphate buffered ten percent formalin bath in a vaccum oven as a control. Hematoxylin and eosin were used to stain the sections. Results equal to and superior to the control method were obtained. Saline microwave fixation was superior to formalin microwave fixation. Tissues placed in Zenker's solution and fixed in standard microwave oven (for approximately one minute) yielded results at least equal to conventional Zenker fixation (approximately two hours). No tissue hardening resulted from Zenker microwave fixation. A unique time versus temperature graph (microwave heating curve) reduces individual variation with this technique.

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions

PubMed Central

Tanti, N.C.; Jones, L.; Sheardown, H.

2010-01-01

Purpose Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. Methods An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate  (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Results Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of β1 and α3 integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Conclusions Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells. PMID:20169012

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions.

PubMed

Gorbet, M B; Tanti, N C; Jones, L; Sheardown, H

2010-02-19

Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of beta(1) and alpha(3) integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells.

Solubility of ammonium acid urate nephroliths from bottlenose dolphins (Tursiops truncatus).

PubMed

Argade, Sulabha; Smith, Cynthia R; Shaw, Timothy; Zupkas, Paul; Schmitt, Todd L; Venn-Watson, Stephanie; Sur, Roger L

2013-12-01

Nephrolithiasis has been identified in managed populations of bottlenose dolphins (Tursiops truncatus); most of these nephroliths are composed of 100% ammonium acid urate (AAU). Several therapies are being investigated to treat and prevent nephrolithiasis in dolphins including the alkalization of urine for dissolution of nephroliths. This study evaluates the solubility of AAU nephroliths in a phosphate buffer, pH range 6.0-8.0, and in a carbonate-bicarbonate buffer, pH range 9.0-10.8. AAU nephroliths were obtained from six dolphins and solubility studies were conducted using reverse-phase high performance liquid chromatography with ultraviolet detection at 290 nm. AAU nephroliths were much more soluble in a carbonate-bicarbonate buffer, pH range 9.0-10.8 compared to phosphate buffer pH range 6.0-8.0. In the pH range 6.0-8.0, the solubility was 45% lower in potassium phosphate buffer compared to sodium phosphate buffer. When citrate was used along with phosphate in the same pH range, the solubility was improved by 13%. At pH 7 and pH 8, 150 mM ionic strength buffer was optimum for dissolution. In summary, adjustment of urinary pH alone does not appear to be a useful way to treat AAU stones in bottlenose dolphins. Better understanding of the pathophysiology of AAU nephrolithiasis in dolphins is needed to optimize kidney stone prevention and treatment.

Corrosion of dental amalgam and mercury vapor emission in vitro.

PubMed

Moberg, L E

1988-10-01

Amalgam specimens were immersed for 30 days in 1) water, 2) 0.9% NaCl in water, 3) 0.9% NaCl and 10 mM phosphate buffer in water, and 4) 0.9% NaCl, 7.7 mM phosphate, and 6.1 mM citric acid in water. The solutions were stored in stoppered glass tubes. Hg-drops were immersed in solutions 1, 2, and 3. The concentration of mercury vapor in the air above the solutions was measured once a day. After 30 days the amounts of Cu, Zn, Hg, and Ag in the solutions were analyzed by atomic absorption spectrophotometry. The results showed that 0.9% NaCl alone or in combination with the additives increased the amounts of elements released into the solutions. The concentration of Hg0 in the glass tubes increased with the amount of Hg in the solutions, with the exception of solution No. 3, from which significantly less Hg0 evaporated. The results indicate that the composition of the saliva, oral hygiene and dietary factors may be determinants of Hg0 emission from amalgams in the oral cavity.

Anions in Electrothermal Supercharging of Proteins with Electrospray Ionization Follow a Reverse Hofmeister Series

PubMed Central

2015-01-01

The effects of different anions on the extent of electrothermal supercharging of proteins from aqueous ammonium and sodium salt solutions were investigated. Sulfate and hydrogen phosphate are the most effective anions at producing high charge state protein ions from buffered aqueous solution, whereas iodide and perchlorate are ineffective with electrothermal supercharging. The propensity for these anions to produce high charge state protein ions follows the following trend: sulfate > hydrogen phosphate > thiocyanate > bicarbonate > chloride > formate ≈ bromide > acetate > iodide > perchlorate. This trend correlates with the reverse Hofmeister series over a wide range of salt concentrations (1 mM to 2 M) and with several physical properties, including solvent surface tension, anion viscosity B-coefficient, and anion surface/bulk partitioning coefficient, all of which are related to the Hofmeister series. The effectiveness of electrothermal supercharging does not depend on bubble formation, either from thermal degradation of the buffer or from coalescence of dissolved gas. These results provide evidence that the effect of different ions in the formation of high charge state ions by electrothermal supercharging is largely a result of Hofmeister effects on protein stability leading to protein unfolding in the heated ESI droplet. PMID:24410546

Prefibrillar Formation Conditions of β-Lactoglobulin by Titration and Chaotropes Urea and KSCN Under Thermal Load

NASA Astrophysics Data System (ADS)

Babcock, Jeremiah; Valdez, Rolando; Brancaleon, Lorenzo

2009-10-01

The harmful growth of toxic oligomers in the formation of protein amyloid fibrils have been connected to degenerative diseases like Alzheimer's and Huntington's diseases. Understanding the fundamental mechanisms behind protein unfolding and subsequent fibrillogenesis may provide a way to stop the process from occurring. The purpose of this study was to identify favorable fibril growth conditions for a globular model protein β-lactoglobulin using the chaotropes urea and KSCN, along with titration of a pH 7.04 phosphate buffer solution at 40 ^oC over five days. Time-resolved and steady-state fluorescence was used to examine the shift in emission of the tryptophan amino acids over the applied denaturation ranges. BLG, a dimer in native form, monomerized and partially unfolded at 5 M Urea, 2 M KSCN and at pH 2 in phosphate buffer in vitro. Exposure of the solutions to continuous heat over time caused a increase in the lifetimes and red shift in the emission spectra, indicating the possible beginning of nucleation. The study has provided a base for continuation of the study of oligomerization and subsequent fibrillation of BLG, which may provide a fundamental mechanism of formation transferable to other proteins in vivo.

Morphological examination of the effects of defibrotide on experimentally induced bladder injury and its relation to interstitial cystitis.

PubMed

Aydin, H; Ercan, F; Cetinel, S; San, T

2001-08-01

This morphological study aims to investigate the effects of defibrotide, a deoxyribonucleic acid derivative drug with cytoprotective, immunosuppressive and vasorelaxant effects, on protamine sulfate induced bladder injury. Wistar albino female rats were catheterized and intravesically infused with phosphate buffered solution (control group) or, either protamine sulfate (bladder injury group) or protamine sulfate+defibrotide (bladder injury+defibrotide group) dissolved in phosphate buffered solution. The morphology of the urinary bladder was investigated using light and electron microscopy. The number of mast cells in the mucosa, mucosal alterations, intercellular junctions, surface topography and the glycosaminoglycan (GAG) layer as well as microvillus formation on the luminal surface were evaluated. In the bladder injury group, ulcerated areas, irregularity of the GAG layer, increased number of mast cells, vacuole formation, dilated perinuclear cistern, formation of pleomorphic and uniform microvilli and dilatations in the intercellular spaces in the urothelium were observed. In the bladder injury+defibrotide group a relatively normal urothelial topography, GAG layer and a few mast cells in the mucosa, some dilatations between the intercellular areas, less uniform microvilli, regular perinuclear cistern and tight junctions were observed. These results show that defibrotide can inhibit PS induced bladder damage.

Sustained ophthalmic delivery of highly soluble drug using pH-triggered inner layer-embedded contact lens.

PubMed

Zhu, Qiang; Cheng, Hongbo; Huo, Yingnan; Mao, Shirui

2018-06-10

In the present work the feasibility of using inner layer-embedded contact lenses (CLs) to achieve sustained release of highly water soluble drug, betaxolol hydrochloride (BH) on the ocular surface was investigated. Blend film of cellulose acetate and Eudragit S100 was selected as the inner layer, while silicone hydrogel was used as outer layer to construct inner layer-embedded contact lenses. Influence of polymer ratio in the blend film on in vitro drug release behavior in phosphate buffered solution or simulated tear fluid was studied and drug-polymer interaction, erosion and swelling of the blend film were characterized to better understand drug-release mechanism. Storage stability of the inner layer-embedded contact lenses in phosphate buffer solution was also conducted, with ignorable drug loss and negligible change in drug release pattern within 30 days. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 240 h in tear fluid, indicating prolonged drug precorneal residence time. In conclusion, cellulose acetate/Eudragit S100 inner layer-embedded contact lenses are quite promising as controlled-release carrier of highly water soluble drug for ophthalmic delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

In vitro metabolic stability of moisture-sensitive rabeprazole in human liver microsomes and its modulation by pharmaceutical excipients.

PubMed

Ren, Shan; Park, Mi-Jin; Kim, Aera; Lee, Beom-Jin

2008-03-01

A reliable method to assess in vitro metabolic stability of rabeprazole and its modulation by Generally Recognized As Safe (GRAS)-listed pharmaceutical excipients was established in human liver microsomes. The metabolic stability of rabeprazole decreased as a function of incubation time, resulting in the formation of thioether rabeprazole via nonenzymatic degradation and enzymatic metabolism. Buffer type was also a determining factor for the degree of both nonenzymatic degradation and enzymatic metabolism. The net extent of enzymatic drug metabolism, obtained by calculating the difference in drug degradation between a microsome-present reaction system and a microsome-free solution, was about 9.20 +/- 0.67% in phosphate buffer and 2.27 +/- 1.76% in Tris buffer, respectively. Rabeprazole exhibited first-order kinetics in microsome-free solution but showed non-linear kinetics in the microsome-present reaction system. The maximal velocity, Vmax, in phosphate buffer was 5.07 microg mL(-1) h(-1) and the Michaelis-Menten constant, Km, was 10.39 microg mL(-1) by computer-fitting to the classical Michaelis-Menten equation for pattern of time-dependent change in the substrate concentration. The intact drug and its thioether form were well resolved and successfully identified by HPLC chromatography and liquid chromatography mass spectroscopy (LC/MS). The metabolic stability of rabeprazole was also modulated by the presence of pharmaceutical excipients. Among the five pharmaceutical excipients tested, poloxamer 188 and Gelucire 44/14 had potentially inhibitory effects on rabeprazole metabolism in human liver microsomes (p < 0.05). A greater understanding of metabolic stability and its modulation by pharmaceutical excipients would be useful for optimizing the bioavailability of rabeprazole at the early formulation stages.

Buffer Modulation of Menadione-Induced Oxidative Stress in Saccharomyces cerevisiae

PubMed Central

Lushchak, Oleh V.; Bayliak, Maria M.; Korobova, Olha V.; Levine, Rodney L.; Lushchak, Volodymyr I.

2012-01-01

The objective of this study was to compare in vivo the effects of bicarbonate and phosphate buffers on surviving and menadione-induced oxidative stress in yeast cells. The latter were treated with different concentrations of menadione in the presence of these two buffers. If at 25 mM concentration of buffers menadione only slightly reduced yeast surviving, at 50 mM concentration cell killing by menadione was much more pronounced in bicarbonate than in phosphate buffer. Although the content of protein carbonyl groups did not show development of oxidative stress under menadione-induced stress, inactivation of aconitase and decrease in glutathione level mirrored its induction. However, cellular glutathione and aconitase activity decrease did not correlate with yeast survival. In vitro, aconitase was more quickly inactivated in 50 mM carbonate, than in 50 mM phosphate buffer. The possible involvement of the carbonate radical in these processes is discussed. PMID:19843376

Buffer modulation of menadione-induced oxidative stress in Saccharomyces cerevisiae.

PubMed

Lushchak, Oleh V; Bayliak, Maria M; Korobova, Olha V; Levine, Rodney L; Lushchak, Volodymyr I

2009-01-01

The objective of this study was to compare, in vivo, the effects of bicarbonate and phosphate buffers on survival and menadione-induced oxidative stress in yeast cells. The latter were treated with different concentrations of menadione in the presence of these two buffers. At 25 mM concentration of buffers, menadione only slightly reduced yeast surviving; at 50 mM concentration, cell killing by menadione was much more pronounced in bicarbonate than in phosphate buffer. Although the content of protein carbonyl groups did not show development of oxidative stress under menadione-induced stress, inactivation of aconitase and decrease in glutathione level mirrored its induction. However, cellular glutathione and aconitase activity decrease did not correlate with yeast survival. In vitro, aconitase was more quickly inactivated in 50 mM carbonate, than in 50 mM phosphate buffer. The possible involvement of the carbonate radical in these processes is discussed.

Simply enhancing throughput of free-flow electrophoresis via organic-aqueous environment for purification of weak polarity solute of phenazine-1-carboxylic acid in fermentation of Pseudomonas sp. M18.

PubMed

Yang, Jing-Hua; Shao, Jing; Wang, Hou-Yu; Dong, Jing-Yu; Fan, Liu-Yin; Cao, Cheng-Xi; Xu, Yu-Quan

2012-09-01

Herein, a simple novel free-flow electrophoresis (FFE) method was developed via introduction of organic solvent into the electrolyte system, increasing the solute solubility and throughput of the sample. As a proof of concept, phenazine-1-carboxylic acid (PCA) from Pseudomonas sp. M18 was selected as a model solute for the demonstration on feasibility of novel FFE method on account of its faint solubility in aqueous circumstance. In the developed method, the organic solvent was added into not only the sample buffer to improve the solubility of the solute, but also the background buffer to construct a uniform aqueous-organic circumstance. These factors of organic solvent percentage and types as well as pH value of background buffer were investigated for the purification of PCA in the FFE device via CE. The experiments revealed that the percentage and the types of organic solvent exerted major influence on the purification of PCA. Under the optimized conditions (30 mM phosphate buffer in 60:40 (v/v) water-methanol at an apparent pH 7.0, 3.26 mL/min background flux, 10-min residence time of injected sample, and 400 V), PCA could be continuously purified from its impurities. The flux of sample injection was 10.05 μL/min, and the recovery was up to 93.7%. An 11.9-fold improvement of throughput was found with a carrier buffer containing 40% (v/v) methanol, compared with the pure aqueous phase. The developed procedure is of evident significance for the purification of weak polarity solute via FFE. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Automatized sspKa measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60°C.

PubMed

Acquaviva, A; Tascon, M; Padró, J M; Gagliardi, L G; Castells, C B

2014-09-01

We measured pKa values of Tris(hydroxymethyl)aminomethane and dihydrogen phosphate; both are commonly used to prepare buffers for reverse-phase liquid chromatography (RPLC), in acetonitrile/water mixtures from 0% to 70% (v/v) (64.6% (w/w)) acetonitrile and at 20, 30, 40, 50, and 60°C. The procedure is based on potentiometric measurements of pH of buffer solutions of variable solvent compositions using a glass electrode and a novel automated system. The method consists in the controlled additions of small volumes of a thermostated solution from an automatic buret into another isothermal solution containing exactly the same buffer-component concentrations, but a different solvent composition. The continuous changes in the solvent composition induce changes in the potentials. Thus, only two sequences of additions are needed: increasing the amount of acetonitrile from pure water and decreasing the content of acetonitrile from 70% (v/v) (64.6% (w/w)). In the procedure with homemade apparatus, times for additions, stirring, homogenization, and data acquisition are entirely controlled by software programmed for this specific routine. This rapid, fully automated method was applied to acquire more than 40 potential data covering the whole composition range (at each temperature) in about two hours and allowed a systematic study of the effect of temperature and acetonitrile composition on acid-base equilibria of two widely used substances to control pH close to 7. The experimental pKa results were fitted to empirical functions between pKa and temperature and acetonitrile composition. These equations allowed predictions of pKa to estimate the pH of mixtures at any composition and temperature, which would be very useful, for instance, during chromatographic method development. Copyright © 2014 Elsevier B.V. All rights reserved.

pH Sensing Properties of Flexible, Bias-Free Graphene Microelectrodes in Complex Fluids: From Phosphate Buffer Solution to Human Serum.

PubMed

Ping, Jinglei; Blum, Jacquelyn E; Vishnubhotla, Ramya; Vrudhula, Amey; Naylor, Carl H; Gao, Zhaoli; Saven, Jeffery G; Johnson, Alan T Charlie

2017-08-01

Advances in techniques for monitoring pH in complex fluids can have a significant impact on analytical and biomedical applications. This study develops flexible graphene microelectrodes (GEs) for rapid (<5 s), very-low-power (femtowatt) detection of the pH of complex biofluids by measuring real-time Faradaic charge transfer between the GE and a solution at zero electrical bias. For an idealized sample of phosphate buffer solution (PBS), the Faradaic current is varied monotonically and systematically with the pH, with a resolution of ≈0.2 pH unit. The current-pH dependence is well described by a hybrid analytical-computational model, where the electric double layer derives from an intrinsic, pH-independent (positive) charge associated with the graphene-water interface and ionizable (negative) charged groups. For ferritin solution, the relative Faradaic current, defined as the difference between the measured current response and a baseline response due to PBS, shows a strong signal associated with ferritin disassembly and the release of ferric ions at pH ≈2.0. For samples of human serum, the Faradaic current shows a reproducible rapid (<20 s) response to pH. By combining the Faradaic current and real-time current variation, the methodology is potentially suitable for use to detect tumor-induced changes in extracellular pH. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The protective effect of supplemental calcium on colonic permeability depends on a calcium phosphate-induced increase in luminal buffering capacity.

PubMed

Schepens, Marloes A A; ten Bruggencate, Sandra J M; Schonewille, Arjan J; Brummer, Robert-Jan M; van der Meer, Roelof; Bovee-Oudenhoven, Ingeborg M J

2012-04-01

An increased intestinal permeability is associated with several diseases. Previously, we have shown that dietary Ca decreases colonic permeability in rats. This might be explained by a calcium-phosphate-induced increase in luminal buffering capacity, which protects against an acidic pH due to microbial fermentation. Therefore, we investigated whether dietary phosphate is a co-player in the effect of Ca on permeability. Rats were fed a humanised low-Ca diet, or a similar diet supplemented with Ca and containing either high, medium or low phosphate concentrations. Chromium-EDTA was added as an inert dietary intestinal permeability marker. After dietary adaptation, short-chain fructo-oligosaccharides (scFOS) were added to all diets to stimulate fermentation, acidify the colonic contents and induce an increase in permeability. Dietary Ca prevented the scFOS-induced increase in intestinal permeability in rats fed medium- and high-phosphate diets but not in those fed the low-phosphate diet. This was associated with higher faecal water cytotoxicity and higher caecal lactate levels in the latter group. Moreover, food intake and body weight during scFOS supplementation were adversely affected by the low-phosphate diet. Importantly, luminal buffering capacity was higher in rats fed the medium- and high-phosphate diets compared with those fed the low-phosphate diet. The protective effect of dietary Ca on intestinal permeability is impaired if dietary phosphate is low. This is associated with a calcium phosphate-induced increase in luminal buffering capacity. Dragging phosphate into the colon and thereby increasing the colonic phosphate concentration is at least part of the mechanism behind the protective effect of Ca on intestinal permeability.

Determination of bromhexine in plasma by reversed-phase liquid chromatography. Interference of lipoproteins on extraction.

PubMed

Johansson, M; Lenngren, S

1988-11-18

Extraction of the hydrophobic tertiary amine bromhexine from plasma using cyclohexane-heptafluorobutanol (99.5:0.5, v/v) was studied at different pH values. The extraction yield from buffer solutions was quantitative at pH greater than 4.1, but from plasma the extraction yield decreased with increasing pH. Furthermore, at pH 8.4 the extraction yield varied greatly (56-99%) in different human plasma. The addition of lipoproteins to phosphate buffer, at pH 8.1, decreased the extraction yields considerably. Quantitative extraction from plasma was obtained by using a very long extraction time at pH 8.4 or by decreasing the pH to 5.4. The chromatographic system consisted of a reversed-phase column (Nucleosil C18, 5 microns) with an acidic mobile phase (methanol-phosphate buffer, pH 2) containing an aliphatic tertiary amine. UV detection at 308 or 254 nm was used. The limit of quantitation was 5 ng/ml using 3.00 ml of plasma and detection at 254 nm. The intra-assay precision for bromhexine was better than 3.6% at 5 ng/ml.

Driving forces and the influence of the buffer composition on the complexation reaction between ibuprofen and HPCD.

PubMed

Perlovich, German L; Skar, Merete; Bauer-Brandl, Annette

2003-10-01

Cyclodextrins are often used in order to increase the aqueous solubility of drug substances by complexation. In order to investigate the complexation reaction of ibuprofen and hydroxypropyl-beta-cyclodextrin, titration calorimetry was used as a direct method. The thermodynamic parameters of the complexation process (stability constant, K(11); complexation enthalpy, deltaH(c) degrees ) were obtained in two different buffer systems (citric acid/sodium-phosphate and phosphoric acid) at various pH values. Based on these data the relative contributions of the enthalpic and entropic terms of the Gibbs energy to the complexation process have been analyzed. In both buffers the enthalpic and entropic terms are of different sign and this case corresponds to a 'nonclassical' model of hydrophobic interaction. In citric buffer, the main driving force of complexation is the entropy, which increases from 60 to 67% while the pH of the solution increases from 3.2 to 8.0. However, for the phosphoric buffer the entropic term decreases from 60 to 45%, while the pH-value of the solution increases from 5.0 to 8.2, and the driving force of the complexation process changes from entropy to enthalpy. The experimental data of the present study are compared to results of other authors and discrepancies discussed in detail.

Studies on the hemolytic activity of tentacle extracts of jellyfish Rhopilema esculentum Kishinouye: application of orthogonal test.

PubMed

Yu, Huahua; Xing, Ronge; Liu, Song; Li, Cuiping; Guo, Zhanyong; Li, Pengcheng

2007-02-20

The present work is first reporting the hemolytic activity of venom from jellyfish Rhopilema esculentum Kishinouye extracted by different phosphate buffer solutions and incubated at different temperature according to the orthogonal test L6(1) x 3(6). Of the seven controllable independent variables, incubated temperature and phenylmethylsulfonyl fluoride (PMSF) had strongest effect on the hemolytic activity.

An aqueous, organic dye derivatized SnO 2 /TiO 2 core/shell photoanode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wee, Kyung-Ryang; Sherman, Benjamin D.; Brennaman, M. Kyle

2016-01-01

Visible light driven water splitting in a dye-sensitized photoelectrochemical cell (DSPEC) based on a phosphonic acid-derivatized donor–π–acceptor (D–π–A) organic dye (P–A–π–D) is described with the dye anchored to an FTO|SnO 2/TiO 2core/shell photoanode in a pH 7 phosphate buffer solution.

Korean Hemorrhagic Fever.

DTIC Science & Technology

1981-03-31

secretions, and ectoparasites were prepared in phosphate buffered saline, pH 7.6 containing 0.2% serum bovine albumin(PBS). Penicillin, streptomycin...water source and urine was collected during an interval of 3-5 hours, in sterile bottles containing 10 ml of Hanks balanced solution(BSS) with 1% bovine ...Shope, R. E. and Harrison, A. Physiocochemical and morphological relationships of some arthropod-borne viruses to bluetongue virus - a new taxonomic

In Vivo Predictive Dissolution: Comparing the Effect of Bicarbonate and Phosphate Buffer on the Dissolution of Weak Acids and Weak Bases.

PubMed

Krieg, Brian J; Taghavi, Seyed Mohammad; Amidon, Gordon L; Amidon, Gregory E

2015-09-01

Bicarbonate is the main buffer in the small intestine and it is well known that buffer properties such as pKa can affect the dissolution rate of ionizable drugs. However, bicarbonate buffer is complicated to work with experimentally. Finding a suitable substitute for bicarbonate buffer may provide a way to perform more physiologically relevant dissolution tests. The dissolution of weak acid and weak base drugs was conducted in bicarbonate and phosphate buffer using rotating disk dissolution methodology. Experimental results were compared with the predicted results using the film model approach of (Mooney K, Mintun M, Himmelstein K, Stella V. 1981. J Pharm Sci 70(1):22-32) based on equilibrium assumptions as well as a model accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . Assuming carbonic acid is irreversible in the dehydration direction: CO2 + H2 O ← H2 CO3 , the transport analysis can accurately predict rotating disk dissolution of weak acid and weak base drugs in bicarbonate buffer. The predictions show that matching the dissolution of weak acid and weak base drugs in phosphate and bicarbonate buffer is possible. The phosphate buffer concentration necessary to match physiologically relevant bicarbonate buffer [e.g., 10.5 mM (HCO3 (-) ), pH = 6.5] is typically in the range of 1-25 mM and is very dependent upon drug solubility and pKa . © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Influence of silica nanospheres on corrosion behavior of magnesium matrix syntactic foam

NASA Astrophysics Data System (ADS)

Qureshi, W.; Kannan, S.; Vincent, S.; Eddine, N. N.; Muhammed, A.; Gupta, M.; Karthikeyan, R.; Badari, V.

2018-04-01

Over the years, the development of Magnesium alloys as biodegradable implants has seen significant advancements. Magnesium based materials tend to provide numerous advantages in the field of biomedical implants over existing materials such as titanium or stainless steel. The present research focuses on corrosive behavior of Magnesium reinforced with different volume percentages of Hollow Silica Nano Spheres (HSNS). These behaviors were tested in two different simulated body fluids (SBF) namely, Hank’s Buffered Saline Solution (HBSS) and Phosphate Buffered Solution (PBS). This corrosion study was done using the method of electrochemical polarization with a three-electrode configuration. Comparative studies were established by testing pure Mg which provided critical information on the effects of the reinforcing material. The HSNS reinforced Mg displayed desirable characteristics after corrosion experiments; increased corrosion resistance was witnessed with higher volume percentage of HSNS.

Effect of bicarbonate on iron-mediated oxidation of low-density lipoprotein

NASA Astrophysics Data System (ADS)

Arai, Hirofumi; Berlett, Barbara S.; Chock, P. Boon; Stadtman, Earl R.

2005-07-01

Oxidation of low-density lipoprotein (LDL) may play an important role in atherosclerosis. We studied the effects of bicarbonate/CO2 and phosphate buffer systems on metal ion-catalyzed oxidation of LDL to malondialdehyde (MDA) and to protein carbonyl and MetO derivatives. Our results revealed that LDL oxidation in mixtures containing free iron or heme derivatives was much greater in bicarbonate/CO2 compared with phosphate buffer. However, when copper was substituted for iron in these mixtures, the rate of LDL oxidation in both buffers was similar. Iron-catalyzed oxidation of LDL was highly sensitive to inhibition by phosphate. Presence of 0.3-0.5 mM phosphate, characteristic of human serum, led to 30-40% inhibition of LDL oxidation in bicarbonate/CO2 buffer. Iron-catalyzed oxidation of LDL to MDA in phosphate buffer was inhibited by increasing concentrations of albumin (10-200 μM), whereas MDA formation in bicarbonate/CO2 buffer was stimulated by 10-50 μM albumin but inhibited by higher concentrations. However, albumin stimulated the oxidation of LDL proteins to carbonyl derivatives at all concentrations examined in both buffers. Conversion of LDL to MDA in bicarbonate/CO2 buffer was greatly stimulated by ADP, ATP, and EDTA but only when EDTA was added at a concentration equal to that of iron. At higher than stoichiometric concentrations, EDTA prevented oxidation of LDL. Results of these studies suggest that interactions between bicarbonate and iron or heme derivatives leads to complexes with redox potentials that favor the generation of reactive oxygen species and/or to the generation of highly reactive CO2 anion or bicarbonate radical that facilitates LDL oxidation. Freely available online through the PNAS open access option.Abbreviations: LDL, low-density lipoprotein; MDA, malondialdehyde; MetO, methionine sulfoxide.

Deduction of a calcium ion circuit affecting rooster sperm in vitro.

PubMed

Froman, D P

2016-08-01

Four premises for rooster sperm preservation were outlined previously. Understanding mitochondrial Ca cycling in terms of whole-cell Ca flux was one premise. The present work tested the hypothesis that sperm mitochondria can be damaged by intracellular as well as extracellular Ca. Sperm were washed by centrifugation through 12% (wt/vol) Sperm were washed by centrifugation through 12%(at/vol) Accudenz to procure sperm at a physiological concentration within a chemically-defined suspension. Five solutions were tested. Each solution contained 30 m glucose, and had an osmolality of 320 mmol/kg and a pH of 7.4. Washed sperm were diluted to 2.0 × 10 sperm/mL. Each replicate sperm suspension was cooled to 10°C. Sperm mobility was measured after 1, 2, 4, 8, 12, and 24 h. Data were plotted as a function of time in each experiment. Function type was confirmed by lack of fit analysis. A parabola with a maximum at 3.7 h was observed when sperm were suspended in 205 m taurine buffered with 50 m-tris[hydroxyl-methyl]methyl-2-amino-ethanesulfonic acid (TES). This effect was attributed to a Ca flux from the nuclear envelope into mitochondria. An exponential decay was observed when TES-buffered taurine contained 2 m Ca. This effect was attributed to mitochondrial Ca overload induced by uptake of extracellular Ca. Exponential decay also was observed when TES-buffered taurine contained a Ca chelator. This effect was attributed to a Ca flux from the nuclear envelope through mitochondria and then into an extracellular Ca sink. This possibility was supported by the response of sperm to thapsigargin. Specifically, inhibition of sarcoendoplasmic reticulum Ca-ATPase compromised sperm mobility relative to a buffer control. Finally, a 60 m phosphate buffer containing 2 m citrate yielded a linear relationship in contrast to the TES-buffered solutions tested. Sperm mobility after 24 h of storage in the phosphate buffer was 92% of that observed for prewashed sperm. The linear response was attributed to weak chelators providing resistance within a Ca circuit and thereby preventing mitochondrial Ca overload. Fertility, however, was compromised when hens were inseminated with mobile sperm recovered after either 8 or 24 h of storage at 10°C. In conclusion, sperm cell Ca homeostasis was proven to be critical for maintaining sperm mobility in vitro, but mitochondrial Ca uptake is not the sole phenomenon that compromises sperm function during in vitro storage.

Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.

PubMed

Gandolfi, Maria Giovanna; Taddei, Paola; Tinti, Anna; De Stefano Dorigo, Elettra; Rossi, Piermaria Luigi; Prati, Carlo

2010-12-01

The bioactivity of calcium silicate mineral trioxide aggregate (MTA) cements has been attributed to their ability to produce apatite in presence of phosphate-containing fluids. This study evaluated surface morphology and chemical transformations of an experimental accelerated calcium-silicate cement as a function of soaking time in different phosphate-containing solutions. Cement discs were immersed in Dulbecco's phosphate-buffered saline (DPBS) or Hank's balanced salt solution (HBSS) for different times (1-180 days) and analysed by scanning electron microscopy connected with an energy dispersive X-ray analysis (SEM-EDX) and micro-Raman spectroscopy. SEM-EDX revealed Ca and P peaks after 14 days in DPBS. A thin Ca- and P-rich crystalline coating layer was detected after 60 days. A thicker multilayered coating was observed after 180 days. Micro-Raman disclosed the 965-cm(-1) phosphate band at 7 days only on samples stored in DPBS and later the 590- and 435-cm(-1) phosphate bands. After 60-180 days, a layer approximately 200-900 μm thick formed displaying the bands of carbonated apatite (at 1,077, 965, 590, 435 cm(-1)) and calcite (at 1,088, 713, 280 cm(-1)). On HBSS-soaked, only calcite bands were observed until 90 days, and just after 180 days, a thin apatite-calcite layer appeared. Micro-Raman and SEM-EDX demonstrated the mineralization induction capacity of calcium-silicate cements (MTAs and Portland cements) with the formation of apatite after 7 days in DPBS. Longer time is necessary to observe bioactivity when cements are immersed in HBSS.

A Janus cobalt-based catalytic material for electro-splitting of water

NASA Astrophysics Data System (ADS)

Cobo, Saioa; Heidkamp, Jonathan; Jacques, Pierre-André; Fize, Jennifer; Fourmond, Vincent; Guetaz, Laure; Jousselme, Bruno; Ivanova, Valentina; Dau, Holger; Palacin, Serge; Fontecave, Marc; Artero, Vincent

2012-09-01

The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable and efficient systems for the conversion and storage of renewable energy sources. The production of hydrogen through water splitting seems a promising and appealing solution. We found that a robust nanoparticulate electrocatalytic material, H2-CoCat, can be electrochemically prepared from cobalt salts in a phosphate buffer. This material consists of metallic cobalt coated with a cobalt-oxo/hydroxo-phosphate layer in contact with the electrolyte and mediates H2 evolution from neutral aqueous buffer at modest overpotentials. Remarkably, it can be converted on anodic equilibration into the previously described amorphous cobalt oxide film (O2-CoCat or CoPi) catalysing O2 evolution. The switch between the two catalytic forms is fully reversible and corresponds to a local interconversion between two morphologies and compositions at the surface of the electrode. After deposition, the noble-metal-free coating thus functions as a robust, bifunctional and switchable catalyst.

TRIS buffer in simulated body fluid distorts the assessment of glass-ceramic scaffold bioactivity.

PubMed

Rohanová, Dana; Boccaccini, Aldo Roberto; Yunos, Darmawati Mohamad; Horkavcová, Diana; Březovská, Iva; Helebrant, Aleš

2011-06-01

The paper deals with the characterisation of the bioactive phenomena of glass-ceramic scaffold derived from Bioglass® (containing 77 wt.% of crystalline phases Na(2)O·2CaO·3SiO(2) and CaO·SiO(2) and 23 wt.% of residual glass phase) using simulated body fluid (SBF) buffered with tris-(hydroxymethyl) aminomethane (TRIS). A significant effect of the TRIS buffer on glass-ceramic scaffold dissolution in SBF was detected. To better understand the influence of the buffer, the glass-ceramic scaffold was exposed to a series of in vitro tests using different media as follows: (i) a fresh liquid flow of SBF containing tris (hydroxymethyl) aminomethane; (ii) SBF solution without TRIS buffer; (iii) TRIS buffer alone; and (iv) demineralised water. The in vitro tests were provided under static and dynamic arrangements. SBF buffered with TRIS dissolved both the crystalline and residual glass phases of the scaffold and a crystalline form of hydroxyapatite (HAp) developed on the scaffold surface. In contrast, when TRIS buffer was not present in the solutions only the residual glassy phase dissolved and an amorphous calcium phosphate (Ca-P) phase formed on the scaffold surface. It was confirmed that the TRIS buffer primarily dissolved the crystalline phase of the glass-ceramic, doubled the dissolving rate of the scaffold and moreover supported the formation of crystalline HAp. This significant effect of the buffer TRIS on bioactive glass-ceramic scaffold degradation in SBF has not been demonstrated previously and should be considered when analysing the results of SBF immersion bioactivity tests of such systems. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Implications for Ophthalmic Formulations: Ocular Buffers Show Varied Cytotoxic Impact on Human Corneal-Limbal and Human Conjunctival Epithelial Cells.

PubMed

Schuerer, Nadine; Stein, Elisabeth; Inic-Kanada, Aleksandra; Pucher, Marion; Hohenadl, Christine; Bintner, Nora; Ghasemian, Ehsan; Montanaro, Jacqueline; Barisani-Asenbauer, Talin

2017-06-01

To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal-limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To detect possible delayed effects on cell viability, after 60 minutes of buffer incubation, cells were further incubated for 24 hours with a cell medium. Cell viability was determined using a colorimetric XTT-based assay. The morphology of cells was also investigated. HCjE cells showed more sensitivity to buffer incubation than HCLE cells. The 100 mM phosphate buffer displayed significant delayed effects on cell viability of HCLE 16.8 ± 4.8% and HCjE 39.2 ± 6.1% cells after 60 minutes of exposure (P < 0.05). HCjE cell viability was reduced after 60 minutes incubations with 50 and 100 mM citrate buffer to 42.8 ± 6.5% and 39.3 ± 7.9%, respectively, and even lower percentages at the delayed time point (both P < 0.05). HCLE cell morphology was distinctly altered by 100 mM phosphate and Tris buffers after 30 minutes, whereas HCjE cells already showed marked changes after 10 minutes of exposure to 100 mM citrate and phosphate buffers. We observed a time-dependent decrease of viability in both HCLE and HCjE cells exposed to higher buffer concentrations. Therefore, we propose further in vivo studies to translate these finding to humans to discern the real effects of the buffer concentration in eye drops on the ocular surface.

Implications for Ophthalmic Formulations: Ocular Buffers Show Varied Cytotoxic Impact on Human Corneal–Limbal and Human Conjunctival Epithelial Cells

PubMed Central

Schuerer, Nadine; Stein, Elisabeth; Inic-Kanada, Aleksandra; Pucher, Marion; Hohenadl, Christine; Bintner, Nora; Ghasemian, Ehsan; Montanaro, Jacqueline

2017-01-01

Purpose: To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal–limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. Methods: HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To detect possible delayed effects on cell viability, after 60 minutes of buffer incubation, cells were further incubated for 24 hours with a cell medium. Cell viability was determined using a colorimetric XTT–based assay. The morphology of cells was also investigated. Results: HCjE cells showed more sensitivity to buffer incubation than HCLE cells. The 100 mM phosphate buffer displayed significant delayed effects on cell viability of HCLE 16.8 ± 4.8% and HCjE 39.2 ± 6.1% cells after 60 minutes of exposure (P < 0.05). HCjE cell viability was reduced after 60 minutes incubations with 50 and 100 mM citrate buffer to 42.8 ± 6.5% and 39.3 ± 7.9%, respectively, and even lower percentages at the delayed time point (both P < 0.05). HCLE cell morphology was distinctly altered by 100 mM phosphate and Tris buffers after 30 minutes, whereas HCjE cells already showed marked changes after 10 minutes of exposure to 100 mM citrate and phosphate buffers. Conclusions: We observed a time-dependent decrease of viability in both HCLE and HCjE cells exposed to higher buffer concentrations. Therefore, we propose further in vivo studies to translate these finding to humans to discern the real effects of the buffer concentration in eye drops on the ocular surface. PMID:28399036

Influence of high-conductivity buffer composition on field-enhanced sample injection coupled to sweeping in CE.

PubMed

Anres, Philippe; Delaunay, Nathalie; Vial, Jérôme; Thormann, Wolfgang; Gareil, Pierre

2013-02-01

The aim of this work was to clarify the mechanism taking place in field-enhanced sample injection coupled to sweeping and micellar EKC (FESI-Sweep-MEKC), with the utilization of two acidic high-conductivity buffers (HCBs), phosphoric acid or sodium phosphate buffer, in view of maximizing sensitivity enhancements. Using cationic model compounds in acidic media, a chemometric approach and simulations with SIMUL5 were implemented. Experimental design first enabled to identify the significant factors and their potential interactions. Simulation demonstrates the formation of moving boundaries during sample injection, which originate at the initial sample/HCB and HCB/buffer discontinuities and gradually change the compositions of HCB and BGE. With sodium phosphate buffer, the HCB conductivity increased during the injection, leading to a more efficient preconcentration by staking (about 1.6 times) than with phosphoric acid alone, for which conductivity decreased during injection. For the same injection time at constant voltage, however, a lower amount of analytes was injected with sodium phosphate buffer than with phosphoric acid. Consequently sensitivity enhancements were lower for the whole FESI-Sweep-MEKC process. This is why, in order to maximize sensitivity enhancements, it is proposed to work with sodium phosphate buffer as HCB and to use constant current during sample injection. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Carboxymethylation on the Rheological Properties of Hyaluronan

PubMed Central

Wendling, Rian J.; Christensen, Amanda M.; Quast, Arthur D.; Atzet, Sarah K.; Mann, Brenda K.

2016-01-01

Chemical modifications made to hyaluronan to enable covalent crosslinking to form a hydrogel or to attach other molecules may alter the physical properties as well, which have physiological importance. Here we created carboxymethyl hyaluronan (CMHA) with varied degree of modification and investigated the effect on the viscosity of CMHA solutions. Viscosity decreased initially as modification increased, with a minimum viscosity for about 30–40% modification. This was followed by an increase in viscosity around 45–50% modification. The pH of the solution had a variable effect on viscosity, depending on the degree of carboxymethyl modification and buffer. The presence of phosphates in the buffer led to decreased viscosity. We also compared large-scale production lots of CMHA to lab-scale and found that large-scale required extended reaction times to achieve the same degree of modification. Finally, thiolated CMHA was disulfide crosslinked to create hydrogels with increased viscosity and shear-thinning aspects compared to CMHA solutions. PMID:27611817

Degradable biocomposite of nano calcium-deficient hydroxyapatite-multi(amino acid) copolymer

PubMed Central

Li, Hong; Gong, Min; Yang, Aiping; Ma, Jian; Li, Xiangde; Yan, Yonggang

2012-01-01

Background and methods A nano calcium-deficient hydroxyapatite (n-CDHA)-multi(amino acid) copolymer (MAC) composite bone substitute biomaterial was prepared using an in situ polymerization method. The composition, structure, and compressive strength of the composite was characterized, and the in vitro degradability in phosphate-buffered solution and preliminary cell responses to the composite were investigated. Results The composite comprised n-CDHA and an amide linkage copolymer. The compressive strength of the composite was in the range of 88–129 MPa, varying with the amount of n-CDHA in the MAC (ranging from 10 wt% to 50 wt%). Weight loss from the composite increased (from 32.2 wt% to 44.3 wt%) with increasing n-CDHA content (from 10 wt% to 40 wt%) in the MAC after the composite was soaked in phosphate-buffered solution for 12 weeks. The pH of the soaking medium varied from 6.9 to 7.5. MG-63 cells with an osteogenic phenotype were well adhered and spread on the composite surface. Viability and differentiation increased with time, indicating that the composite had no negative effects on MG-63 cells. Conclusion The n-CDHA-MAC composite had good cytocompatibility and has potential to be used as a bone substitute. PMID:22457591

Influence of calcium and phosphorus, lactose, and salt-to-moisture ratio on Cheddar cheese quality: pH buffering properties of cheese.

PubMed

Upreti, P; Bühlmann, P; Metzger, L E

2006-03-01

The pH buffering capacity of cheese is an important determinant of cheese pH. However, the effects of different constituents of cheese on its pH buffering capacity have not been fully clarified. The objective of this study was to characterize the chemical species and chemical equilibria that are responsible for the pH buffering properties of cheese. Eight cheeses with 2 levels of Ca and P (0.67 and 0.47% vs. 0.53 and 0.39%, respectively), residual lactose (2.4 vs. 0.78%), and salt-to-moisture ratio (6.4 vs. 4.8%) were manufactured. The pH-titration curves for these cheeses were obtained by titrating cheese:water (1:39 wt/wt) dispersions with 1 N HCl, and backtitrating with 1 N NaOH. To understand the role of different chemical equilibria and the respective chemical species in controlling the pH of cheese, pH buffering was modeled mathematically. The 36 chemical species that were found to be relevant for modeling can be classified as cations (Na+, Ca2+, Mg2+), anions (phosphate, citrate, lactate), protein-bound amino acids with a side-chain pKa in the range of 3 to 9 (glutamate, histidine, serine phosphate, aspartate), metal ion complexes (phosphate, citrate, and lactate complexes of Na+, Ca2+, and Mg2+), and calcium phosphate precipitates. A set of 36 corresponding equations was solved to give the concentrations of all chemical species as a function of pH, allowing the prediction of buffering curves. Changes in the calculated species concentrations allowed the identification of the chemical species and chemical equilibria that dominate the pH buffering properties of cheese in different pH ranges. The model indicates that pH buffering in the pH range from 4.5 to 5.5 is predominantly due to a precipitate of Ca and phosphate, and the protonation equilibrium involving the side chains of protein-bound glutamate. In the literature, the precipitate is often referred to as amorphous colloidal calcium phosphate. A comparison of experimental data and model predictions shows that the buffering properties of the precipitate can be explained, assuming that it consists of hydroxyapatite [Ca5(OH)(PO4)3] or Ca3(PO4)2. The pH buffering in the region from pH 3.5 to 4.5 is due to protonation of side-chain carboxylates of protein-bound glutamate, aspartate, and lactate, in order of decreasing significance. In addition, pH buffering between pH 5 to 8 in the backtitration results from the reprecipitation of calcium and phosphate either as CaHPO4 or Ca4H(PO4)3.

Effect of synovial fluid, phosphate-buffered saline solution, and water on the dissolution and corrosion properties of CoCrMo alloys as used in orthopedic implants.

PubMed

Lewis, A C; Kilburn, M R; Papageorgiou, I; Allen, G C; Case, C P

2005-06-15

The corrosion and dissolution of high- and low-carbon CoCrMo alloys, as used in orthopedic joint replacements, were studied by immersing samples in phosphate-buffered saline (PBS), water, and synovial fluid at 37 degrees C for up to 35 days. Bulk properties were analyzed with a fine ion beam microscope. Surface analyses by X-ray photoelectron spectroscopy and Auger electron spectroscopy showed surprisingly that synovial fluid produced a thin oxide/hydroxide layer. Release of ions into solution from the alloy also followed an unexpected pattern where synovial fluid, of all the samples, had the highest Cr concentration but the lowest Co concentration. The presence of carbide inclusions in the alloy did not affect the corrosion or the dissolution mechanisms, although the carbides were a significant feature on the metal surface. Only one mechanism was recognized as controlling the thickness of the oxide/hydroxide interface. The analysis of the dissolved metal showed two mechanisms at work: (1) a protein film caused ligand-induced dissolution, increasing the Cr concentration in synovial fluid, and was explained by the equilibrium constants; (2) corrosion at the interface increased the Co in PBS. The effect of prepassivating the samples (ASTM F-86-01) did not always have the desired effect of reducing dissolution. The release of Cr into PBS increased after prepassivation. The metal-synovial fluid interface did not contain calcium phosphate as a deposit, typically found where samples are exposed to calcium rich bodily fluids. (c) 2005 Wiley Periodicals, Inc.

A comparison of the biocompatibility of phosphate-buffered saline and dianeal 3.86% in the rat model of peritoneal dialysis.

PubMed

Wieczorowska-Tobis, K; Polubinska, A; Breborowicz, A; Oreopoulos, D G

2001-01-01

Phosphate-buffered saline (PBS), an isotonic solution with a physiologic pH can be considered an example of a biocompatible dialysis fluid. This study compared the biocompatibility of PBS with that of Dianeal 3.86% (Baxter Healthcare Corporation, Deerfield, IL, U.S.A.), using a model of peritoneal dialysis in the rat. In an acute experiment, after catheter implantation, rats were infused on day 1 with PBS, on day 5 with standard dialysis solution (Dianeal 3.86%), and on day 7 again with PBS. When rats were injected with Dianeal 3.86%, the inflammatory reaction was suppressed as compared with PBS. The cell count was lower with Dianeal (-85%, p < 0.001), the neutrophil:macrophage ratio in dialysate was 80% lower (p < 0.01), total protein concentration in the Dianeal dialysate was 73% lower (p < 0.01), and the dialysate nitrite level was 45% lower (p < 0.01). In a chronic experiment, after catheter implantation, rats were dialyzed for four weeks with PBS or with Dianeal 3.86%. At the end of the study, a 1-hour peritoneal equilibration test (PET) was performed. As evaluated on a semiquantitative scale, macroscopic changes in the peritoneum were more severe in rats exposed to PBS than in those exposed to Dianeal 3.86% (8.6 +/- 3.2 vs 5.2 +/- 2.6, p < 0.05). The thickness of the visceral peritoneum was comparable in both groups; but, in PBS-treated rats, the peritoneal interstitium contained more inflammatory cells and more new vessels. During the 1-hour PET, peritoneal permeability to water and solutes was comparable in the two groups. Despite a more physiologic composition, PBS is a less biocompatible peritoneal dialysis solutions than is standard, acidic, hypertonic dialysis solution.

Effect of Biomineralization Ability on Push-out Strength of Proroot Mineral Trioxide Aggregate, Mineral Trioxide Aggregate Branco, and Calcium Phosphate Cement on Dentin: An In vitro Evaluation.

PubMed

Revankar, Vanita D; Prathap, M S; Shetty, K Harish Kumar; Shahul, Azmin; Sahana, K

2017-11-01

Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc¸o˜es Odontolo´gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. A two-way analysis of variance and post hoc analysis by Bonferroni test. All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group ( P < 0.05). MTAs displayed a significantly greater resistance to displacement than calcium phosphate cements. The main conclusion of this study was that the push-out bond strength of the cements, mainly the MTA groups, was positively influenced by the biomineralization process.

Voltammetric analysis of N-containing drugs using the hanging galinstan drop electrode (HGDE).

PubMed

Channaa, H; Surmann, P

2009-03-01

The electrochemical behaviour of several N-containing voltammetric active drugs such as 1,4-benzodiazepines (chlordiazepoxide, nitrazepam and diazepam) as well as one nitro-compound (nitrofurantoin) and one azo-compound (phenazopyridine) is described using a new kind of liquid electrode, the hanging galinstan drop electrode. Concentrations of 10(-5) - 10(-8) mol L(-1) are generally measurable. Differential pulse and adsorptive stripping voltammograms are recorded in different supporting electrolytes, like 0.1 M KNO3, acetate buffer solution pH = 4.6 and phosphate buffer solution pH = 7.0. The effects of varying the starting potentials, U(start) for DPV and accumulation times, t(acc) for AdSV are considered. Briefly, it is shown that the novel galinstan electrode is suitable for reducing several functional groups in organic substances, here presented for N-oxide-, azomethine-, nitro- and azo-groups.

A Chemist’s Perspective on the Role of Phosphorus at the Origins of Life

PubMed Central

Fernández-García, Christian; Coggins, Adam J.

2017-01-01

The central role that phosphates play in biological systems, suggests they also played an important role in the emergence of life on Earth. In recent years, numerous important advances have been made towards understanding the influence that phosphates may have had on prebiotic chemistry, and here, we highlight two important aspects of prebiotic phosphate chemistry. Firstly, we discuss prebiotic phosphorylation reactions; we specifically contrast aqueous electrophilic phosphorylation, and aqueous nucleophilic phosphorylation strategies, with dry-state phosphorylations that are mediated by dissociative phosphoryl-transfer. Secondly, we discuss the non-structural roles that phosphates can play in prebiotic chemistry. Here, we focus on the mechanisms by which phosphate has guided prebiotic reactivity through catalysis or buffering effects, to facilitating selective transformations in neutral water. Several prebiotic routes towards the synthesis of nucleotides, amino acids, and core metabolites, that have been facilitated or controlled by phosphate acting as a general acid–base catalyst, pH buffer, or a chemical buffer, are outlined. These facile and subtle mechanisms for incorporation and exploitation of phosphates to orchestrate selective, robust prebiotic chemistry, coupled with the central and universally conserved roles of phosphates in biochemistry, provide an increasingly clear message that understanding phosphate chemistry will be a key element in elucidating the origins of life on Earth. PMID:28703763

Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

PubMed

Rezende, Helen Cristine; Coelho, Nivia Maria Melo

2014-01-01

An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

Internal acid buffering in San Joaquin Valley fog drops and its influence on aerosol processing

NASA Astrophysics Data System (ADS)

Collett, Jeffrey L.; Hoag, Katherine J.; Rao, Xin; Pandis, Spyros N.

Although several chemical pathways exist for S(IV) oxidation in fogs and clouds, many are self-limiting: as sulfuric acid is produced and the drop pH declines, the rates of these pathways also decline. Some of the acid that is produced can be buffered by uptake of gaseous ammonia. Additional internal buffering can result from protonation of weak and strong bases present in solution. Acid titrations of high pH fog samples (median pH=6.49) collected in California's San Joaquin Valley reveal the presence of considerable internal acid buffering. In samples collected at a rural location, the observed internal buffering could be nearly accounted for based on concentrations of ammonia and bicarbonate present in solution. In samples collected in the cities of Fresno and Bakersfield, however, significant additional, unexplained buffering was present over a pH range extending from approximately four to seven. The additional buffering was found to be associated with dissolved compounds in the fogwater. It could not be accounted for by measured concentrations of low molecular weight ( C1- C3) carboxylic acids, S(IV), phosphate, or nitrophenols. The amount of unexplained buffering in individual fog samples was found to correlate strongly with the sum of sample acetate and formate concentrations, suggesting that unmeasured organic species may be important contributors. Simulation of a Bakersfield fog episode with and without the additional, unexplained buffering revealed a significant impact on the fog chemistry. When the additional buffering was included, the simulated fog pH remained 0.3-0.7 pH units higher and the amount of sulfate present after the fog evaporated was increased by 50%. Including the additional buffering in the model simulation did not affect fogwater nitrate concentrations and was found to slightly decrease ammonium concentrations. The magnitude of the buffering effect on aqueous sulfate production is sensitive to the amount of ozone present to oxidize S(IV) in these high pH fogs.

Improvement of Starch Digestion Using α-Amylase Entrapped in Pectin-Polyvinyl Alcohol Blend

PubMed Central

Cruz, Maurício; Fernandes, Kátia; Cysneiros, Cristine; Nassar, Reginaldo; Caramori, Samantha

2015-01-01

Polyvinyl alcohol (PVA) and pectin blends were used to entrap α-amylase (Termamyl) using glutaraldehyde as a cross-linker. The effect of glutaraldehyde concentration (0.25, 0.5, 0.75, 1.0, and 1.25%) on the activity of the immobilized enzyme and rate of enzyme released was tested during a 24 h period. Characteristics of the material, such as scanning electron microscopy (SEM), tensile strength (TS), elongation, and rate of dissolution in water (pH 5.7), ruminal buffering solution (pH 7.0), and reactor containing 0.1 mol L−1 sodium phosphate buffer (pH 6.5), were also analyzed. SEM results showed that the surfaces of the pectin/PVA/amylase films were highly irregular and rough. TS values increased as a function of glutaraldehyde concentration, whereas percentage of elongation (%E) decreased. Pectin/PVA/amylase films presented similar values of solubility in the tested solvents. The material obtained with 0.25% glutaraldehyde performed best with repeated use (active for 24 h), in a phosphate buffer reactor. By contrast, the material obtained with 1.25% glutaraldehyde presented higher performance during in vitro testing using an artificial rumen. The results suggest that pectin/PVA/amylase is a highly promising material for biotechnological applications. PMID:25949991

In vitro dissolution of proton-pump inhibitor products intended for paediatric and geriatric use in physiological bicarbonate buffer.

PubMed

Liu, Fang; Shokrollahi, Honaz

2015-05-15

Proton-pump inhibitor (PPI) products based on enteric coated multiparticulates are design to meet the needs of patients who cannot swallow tablets such as children and older adults. Enteric coated PPI preparations exhibit delays in in vivo absorption and onset of antisecretory effects, which is not reflected by the rapid in vitro dissolution in compendial pH 6.8 phosphate buffer commonly used for assessment of these products. A more representative and physiological medium, pH 6.8 mHanks bicarbonate buffer, was used in this study to evaluate the in vitro dissolution of enteric coated multiparticulate-based PPI products. Commercially available omeprazole, lansoprazole and esomeprazole products were subject to dissolution tests using USP-II apparatus in pH 4.5 phosphate buffer saline for 45 min (acid stage) followed by pH 6.8 phosphate buffer or pH 6.8 mHanks bicarbonate buffer. In pH 6.8 phosphate buffer, all nine tested products displayed rapid and comparable dissolution profiles meeting the pharmacopeia requirements for delayed release preparations. In pH 6.8 mHanks buffer, drug release was delayed and failed the pharmacopeia requirements from most enteric coated preparations. Despite that the same enteric polymer, methacrylic acid-ethyl acrylate copolymer (1:1), was applied to all commercial multiparticulate-based products, marked differences were observed between dissolution profiles of these preparations. The use of pH 6.8 physiological bicarbonate (mHanks) buffer can serve as a useful tool to provide realistic and discriminative in vitro release assessment of enteric coated PPI preparations and to assist rational formulation development of these products. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinetic behaviour of calf intestinal alkaline phosphatase with pNPP.

PubMed

Chaudhuri, Gouri; Chatterjee, Saswata; Venu-Babu, P; Ramasamy, K; Thilagaraj, W Richard

2013-02-01

The hydrolysis of p-nitrophenyl phosphate (pNPP) by calf intestinal alkaline phosphatase (CIAP) was investigated with respect to kinetic parameters such as V(max), K(m) and K(cat) under varying pH, buffers, substrate concentration, temperature and period of incubation. Highest activity was obtained with Tris-HCl at pH 11, while in the case of glycine-NaOH buffer the peak activity was recorded at pH 9.5. The enzyme showed the following kinetic characteristics with pNPP in 50 mM Tris-HCl at pH 11 and 100 mM glycine-NaOH at pH 9.5 at an incubation temperature of 37 degrees C: V(max), 3.12 and 1.6 micromoles min(-1) unit(-1); K(m), 7.6 x 10(-4) M and 4 x 10(-4) M; and K(cat), 82.98 s(-1) and 42.55 s(-1), respectively. CIAP displayed a high temperature optimum of 45 degrees C at pH 11. The kinetic behaviour of the enzyme under different parameters suggested that the enzyme might undergo subtle conformational changes in response to the buffers displaying unique characteristics. Bioprecipitation of Cu2+ from 50 ppm of CuCl2 solution was studied where 64.3% of precipitation was obtained. P(i) generated from CIAP-mediated hydrolysis of pNPP was found to bind with copper and precipitated as copper-phosphate. Thus, CIAP could be used as a test candidate in bioremediation of heavy metals from industrial wastes through generation of metal-phosphate complexes.

Evaluation of ocular and general safety following repeated dosing of dexamethasone phosphate delivered by transscleral iontophoresis in rabbits.

PubMed

Patane, Michael A; Schubert, William; Sanford, Thomas; Gee, Raymond; Burgos, Melissa; Isom, William P; Ruiz-Perez, Begona

2013-10-01

To evaluate the toxicokinetics and tolerability (local ocular and general toxicity) of the anti-inflammatory agent, dexamethasone phosphate (a prodrug of dexamethasone) delivered to the eye in rabbits by transscleral iontophoresis. Female rabbits (n=6/group) received dexamethasone phosphate (40 mg/mL ophthalmic solution, EGP-437) transsclerally to the right eye (OD) using the Eyegate(®) II ocular iontophoresis delivery system once biweekly for 24 consecutive weeks at current doses of 10, 14, and 20 mA-min and current levels up to, and including -4 mA for 3.5-5 min. The study included 2 control groups (n=6/group): (1) a noniontophoresis control [an ocular applicator-loaded citrate buffer (placebo) without current] and (2) an iontophoresis control (a citrate buffer plus cathode iontophoresis at 20 mA-min, -4 mA for 5 min). Recoverability was evaluated 4 weeks following the last dose in 2 animals per group. The left eye (OS) was untreated and served as an internal control for each animal. Ocular and general safety of dexamethasone phosphate and dexamethasone were assessed. Other evaluations included toxicokinetics, ophthalmic examinations, intraocular pressure (IOP) measurements, electroretinographs, clinical observations, body weight, hematology and serum chemistry, gross necropsy, organ weight, and microscopic histopathology. The biweekly transscleral iontophoresis with either the citrate buffer or dexamethasone phosphate at cathodic doses up to, and including 20 mA-min and currents up to, and including -4 mA for 24 weeks was well-tolerated. Transient signs of conjunctival hyperemia and chemosis, mild corneal opacity, and fluorescein staining of the cornea were noted and attributed to expected ocular reactions to the temporary placement of the ocular applicator and application of iontophoresis. There were no dexamethasone phosphate-, dexamethasone-, or iontophoresis-related effects on IOP, electroretinography, or histopathology. Reductions in body weight gain, anemia, decreased leukocyte and lymphocyte counts, compromised liver function, enlarged liver, and reduced spleen weight were consistent with systemic corticosteroid-mediated pharmacology, repeated use of anesthesia, stress, and sedentariness, and unlikely to be related to iontophoresis application. The results of this investigation suggest that repeated transscleral iontophoresis with dexamethasone phosphate may be safe for use as a treatment for inflammatory ocular disorders that require prolonged and/or repeated corticosteroid therapy.

Comparative Analysis of Two Biological Warfare Air Samplers Using Live Surrogate Agents

DTIC Science & Technology

2012-03-01

extensively for Phosphate Buffer Saline (PBS) solution and water , and, to a very limited degree in AF evaluations, for virus preserving media, specifically...or water . Furthermore, viral studies have been conducted comparing the effectiveness of utilizing the reduced secondary flow rate on the XMX/2L...with using bioagent aerosols rated BSL-2 or higher. Male Specific Coliphage 2 (MS2), American Type Culture Collection (ATCC) 15597-B1, was selected

31P-Nuclear Magnetic Resonance Determination of Phosphate Compartmentation in Leaves of Reproductive Soybeans (Glycine max L.) as Affected by Phosphate Nutrition 1

PubMed Central

Lauer, Michael J.; Blevins, Dale G.; Sierzputowska-Gracz, Hanna

1989-01-01

Most leaf phosphorus is remobilized to the seed during reproductive development in soybean. We determined, using 31P-NMR, the effect phosphorus remobilization has on vacuolar inorganic phosphate pool size in soybean (Glycine max [L.] Merr.) leaves with respect to phosphorus nutrition and plant development. Phosphate compartmentation between cytoplasmic and vacuolar pools was observed and followed in intact tissue grown hydroponically, at the R2, R4, and R6 growth stages. As phosphorus in the nutrient solution decreased from 0.45 to 0.05 millimolar, the vacuolar phosphate peak became less prominent relative to cytoplasmic phosphate and hexose monophosphate peaks. At a nutrient phosphate concentration of 0.05 millimolar, the vacuolar phosphate peak was not detectable. At higher levels of nutrient phosphate, as plants progressed from the R2 to the R6 growth stage, the vacuolar phosphate peak was the first to disappear, suggesting that storage phosphate was remobilized to a greater extent than metabolic phosphate. Under suboptimal phosphate nutrition (≤ 0.20 millimolar), the hexose monophosphate and cytoplasmic phosphate peaks declined earlier in reproductive development than when phosphate was present in optimal amounts. Under low phosphate concentrations (0.05 millimolar) cytoplasmic phosphate was greatly reduced. Carbon metabolism was coincidently disrupted under low phosphate nutrition as shown by the appearance of large, prominent starch grains in the leaves. Cytoplasmic phosphate, and leaf carbon metabolism dependent on it, are buffered by vacuolar phosphate until late stages of reproductive growth. Images Figure 4 PMID:16666705

Complexation in two-component chlortetracycline-melanin solutions

NASA Astrophysics Data System (ADS)

Lapina, V. A.; Pershukevich, P. P.; Dontsov, A. E.; Bel'Kov, M. V.

2008-01-01

The spectra and kinetics of fluorescence of two-component solutions of the chlortetracycline (CHTC)-DOPA-melanin (melanin or ME) system in water have been investigated. The data obtained have been compared to similar data for solutions of CHTC-melanosome from bull eye (MB), which contains natural melanin, in K-phosphate buffer at pH 7.4. The overall results indicate the occurrence of complexation between molecules of CHTC and ME as they are being excited. The studies of complexation in the solution of CHTC-MB in the buffer are complicated by the formation of a CHTC-buffer complex. The effect of optical radiation in the range 330-750 nm on the CHTC-ME complex shows selectivity: the greatest change in the spectrum occurs when the wavelength of the exciting radiation coincides with the long-wavelength band maximum of the fluorescence excitation spectrum of the CHTC-ME complex in aqueous solution. In this range, CHTC and especially ME show high photochemical stability. The nature of the radiation effect on the studied compounds in the hard UV range (λ < 330 nm) differs greatly from that in the range 330-750 nm. It is apparently accompanied by significant photochemical transmutations of all system components. By comparing the characteristics of the CHTC-ME systems with those of the related drug doxycycline (DC-ME), the conclusion has been made that the chlorine atom plays a vital role in formation of the short-wavelength band in the fluorescence spectrum of the CHTC-ME complex.

Biosorption of mercury by the inactivated cells of Pseudomonas aeruginosa PU21 (Rip64)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, J.S.; Hong, J.

1994-10-01

Biomass of a mercury-resistance strain Pseudomonas aeruginosa PU21 (Rip64) and hydrogen-form cation exchange resin (AG 50W-X8) were investigated for their ability to adsorb mercury. The maximum adsorption capacity was approximately 180 mg Hg/g dry cell in deionized water and 400 mg Hg/g dry cell in sodium phosphate solution of pH 7.4, higher than the maximum mercury uptake capacity in the cation exchange resin. The mercury selectivity of the biomass over sodium ions was evaluated when 50 mM and 150 mM of Na[sup +] were present. Biosorption of mercury was also examined in sodium phosphate solution and phosphate-buffered saline solution containingmore » 50 mM and 150 mM of Na[sup +], respectively. It was found that the presence of Na[sup +] did not severely affect the biosorption of Hg[sup 2+], indicating a high mercury selectivity of the biomass over sodium ions. In contrast, the mercury uptake by the ion exchange resin was strongly inhibited by high sodium concentrations. The mercury biosorption was most favorable in sodium phosphate solution (pH 7.4), with a more than twofold increase in the maximum mercury uptake capacity. The pH was found to affect the adsorption of Hg[sup 2+] by the biomass and the optimal pH value was approximately 7.4. The adsorption of mercury on the biomass and the ion exchange resin appeared to follow the Langmuir or Freundlich adsorption isotherms.« less

Histological preparation of developing vestibular otoconia for scanning electron microscopy

NASA Technical Reports Server (NTRS)

Huss, D.; Dickman, J. D.

2003-01-01

The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanning electron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

Long-Term In Vitro Degradation of a High-Strength Brushite Cement in Water, PBS, and Serum Solution

PubMed Central

Ajaxon, Ingrid; Öhman, Caroline; Persson, Cecilia

2015-01-01

Bone loss and fractures may call for the use of bone substituting materials, such as calcium phosphate cements (CPCs). CPCs can be degradable, and, to determine their limitations in terms of applications, their mechanical as well as chemical properties need to be evaluated over longer periods of time, under physiological conditions. However, there is lack of data on how the in vitro degradation affects high-strength brushite CPCs over longer periods of time, that is, longer than it takes for a bone fracture to heal. This study aimed at evaluating the long-term in vitro degradation properties of a high-strength brushite CPC in three different solutions: water, phosphate buffered saline, and a serum solution. Microcomputed tomography was used to evaluate the degradation nondestructively, complemented with gravimetric analysis. The compressive strength, chemical composition, and microstructure were also evaluated. Major changes from 10 weeks onwards were seen, in terms of formation of a porous outer layer of octacalcium phosphate on the specimens with a concomitant change in phase composition, increased porosity, decrease in object volume, and mechanical properties. This study illustrates the importance of long-term evaluation of similar cement compositions to be able to predict the material's physical changes over a relevant time frame. PMID:26587540

Biodegradable neural cell culture sheet made of poly(lactic-co-glycolic acid) thin film with micropatterns of Dulbecco’s phosphate-buffered saline (-) containing laminin layers

NASA Astrophysics Data System (ADS)

Nakamura, Yuki; Horiuchi, Shunpu; Nishioka, Yasushiro

2018-02-01

In the regenerative medicine field of nervous systems, techniques used to fabricate microstructures of neurons on flexible and biodegradable substrates have attracted attention. In this research, biodegradable and flexible neuron culture thin films that enable the selective axonal outgrowth of neurons were fabricated using poly(lactic-co-glycolic acid) (PLGA) thin films with micropatterns of Dulbecco’s phosphate-buffered saline (D-PBS) (-) containing laminin layers. The 100-µm-thick PLGA thin films were fabricated by diluting PLGA in acetone (5% w/w) and the solution was distributed onto a poly(dimethylsiloxane) (PDMS) mold. D-PBS (-) micropatterns containing laminin layers with widths of 10-150 µm were fabricated by micromolding in capillaries (MIMIC) and the microstencil method. Rat neurons were selectively cultured for 3 d on the laminin micropatterns; using the MIMIC method, the cells properly adhered to a pattern wider than 30 µm, while with the microstencil method, the necessary pattern width for proper adhesion was more than 50 µm.

Development of gastro intestinal sustained release tablet formulation containing acryl-EZE and pH-dependent swelling HPMC K 15 M.

PubMed

Lamoudi, Lynda; Chaumeil, Jean Claude; Daoud, Kamel

2012-05-01

The aim of this study was to evaluate physical properties and release from matrix tablets containing different ratios of HPMC 15 M and Acryl-EZE. A further aim is to assess their suitability for pH dependent controlled release. Matrix tablets containing HPMC 15 M and Acryl-EZE were manufactured using a fluidized bed. The release from this matrix using Sodium Diclofenac (SD) as model drug is studied in two dissolution media (0.1 N HCl or pH = 6.8 phosphate buffer solution); the release rate, mechanism, and pH dependence were characterized by fitting four kinetic models and by using a similarity factor analysis. The obtained results revealed that the presence of Acryl-EZE in the matrix tablets is effective in protecting the dosage forms from release in acid environments such as gastric fluid. In pH = 6.8 phosphate buffer, the drug release rate and mechanism of release from all matrices is mainly controlled by HPMC 15 M. The model of Korsmeyer-Peppas was found to fit experimental dissolution results.

The adsorption mechanism of nortryptiline on C18-bonded discovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A

2005-08-01

The adsorption isotherms of an ionizable compound, nortriptyline, were accurately measured by frontal analysis (FA) on a C{sub 18}-Discovery column, first without buffer (in an aqueous solution of acetonitrile at 15%, v/v of ACN), then with a buffer (in 28%, v/v ACN solution). The buffers were aqueous solutions containing 20 mM of formic acid or a phosphate buffer at pH 2.70. The linear range of the isotherm could not be reached with the non-buffered mobile phase using a dynamic range larger than 40,000 (from 1.2 x 10{sup -3} g/L to 50 g/L). With a 20 mM buffer in the liquidmore » phase, the isotherm is linear for concentrations of nortriptyline inferior to 10{sup -3} g/L (or 3 {micro} mol/L). The adsorption energy distribution (AED) was calculated to determine the heterogeneity of the adsorption process. AED and FA were consistent and lead to a trimodal distribution. A tri-Moreau and a tri-Langmuir isotherm models accounted the best for the adsorption of nortriptyline without and with buffer, respectively. The nature of the buffer affects significantly the middle-energy sites while the properties of the lowest and highest of the three types of energy sites are almost unchanged. The desorption profiles of nortriptyline show some anomalies in relation with the formation of a complex multilayer adsorbed phase of acetonitrile whose excess isotherm was measured by the minor disturbance method. The C{sub 18}-Discovery column has about the same total saturation capacity, around 200 g of nortriptyline per liter of adsorbent (or 116 mg/g), with or without buffer. About 98-99% of the available surface consists in low energy sites. The coexistence of these different types of sites on the surface solves the McCalley's enigma, that the column efficiency begins to drop rapidly when the analyte concentration reaches values that are almost one hundred times lower than those that could be predicted from the isotherm data acquired under the same experimental conditions. Due to the presence of some relatively rare high energy sites, the largest part of the saturation capacity is not practically useful.« less

Final report of the key comparison APMP.QM-K9: APMP comparison on pH measurement of phosphate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Ohata, Masaki; Cherdchu, Chainarong; Tangpaisarnkul, Nongluck

2011-01-01

The APMP.QM-K9 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phosphate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan, NMIJ, and the National Institute of Metrology of Thailand, NIMT, in August 2009. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K9, CCQM-K9.1 and CCQM-K9.2. The comparison material was a phosphate buffer of pH around 6.86 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the first APMP key comparison on pH measurement and the third APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004 and APMP.QM-P09 (a phthalate buffer) in 2006. The results can be used further by any participant to support its CMC claim for a phosphate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the temperature(s) used or the full temperature range between 15 °C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

A phosphorus-free anolyte to enhance coulombic efficiency of microbial fuel cells

NASA Astrophysics Data System (ADS)

Tang, Xinhua; Li, Haoran; Du, Zhuwei; Ng, How Yong

2014-12-01

In this study, a phosphorus-free anolyte is prepared by using bicarbonate to replace phosphate buffer for application in two chamber microbial fuel cells (MFCs). Optical density test and Bradford protein assay shows that this phosphorus-free anolyte effectively inhibits the growth and reproduction of microorganisms suspended in the solution and greatly reduces the suspended cell mass. As a result, it considerably enhances the coulombic efficiency (CE) of MFCs. When the acetate concentration is 11 mM, the CE of the MFC using the pH 7 phosphate-containing anolyte is 9.7% and the CE with the pH 8.3 phosphate-containing anolyte is 9.1%, while the CE of the MFC using the phosphorus-free anolyte (pH 8.3) achieves 26.6%. This study demonstrates that this phosphorus-free anolyte holds the potential to enhance the feasibility for practical applications of MFCs.

Drop Migration and Demixing of Biphasic Aqueous Systems in an Applied Electric Field

NASA Astrophysics Data System (ADS)

Todd, Paul; Raghavarao, Karumanchi S. M. S.

1999-11-01

Applying an electric field to a demixing emulsion of poly(ethylene glycol)(PEG) and dextran (or maltodextrin) in phosphate-buffered aqueous solution shortens the demixing time up to 6 fold. Phosphate ions partition into the dextran-rich phase imparting a small electrical potential between the phases. PEG-rich drops migrate cathodally, and their electrophoretic mobility is directly proportional to their radius and increases with increased ionization of phosphate. An electric field, either parallel or antiparallel to the gravity vector, can enhance demixing. A theory consistent with these observations states that drops move due to external and internal electroosmotic flow (tractor treading). Enhanced demixing in an electric field whose polarity opposes buoyancy is thought to be caused by initial increased drop growth during retardation by the electric field so that the drop becomes more buoyant. However, at infinite internal drop viscosity the theory does not extrapolate to the result for solid colloid particles.

Nanophase iron phosphate, iron arsenate, iron vanadate, and iron molybdate minerals synthesized within the protein cage of ferritin.

PubMed

Polanams, Jup; Ray, Alisha D; Watt, Richard K

2005-05-02

Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin.

Ex vivo evaluation of various instrumentation techniques and irrigants in reducing E. faecalis within root canals.

PubMed

Basmaci, F; Oztan, M D; Kiyan, M

2013-09-01

To evaluate ex vivo the effectiveness of single-file instrumentation techniques compared with serial Ni-Ti rotary instrumentation with several irrigation regimens in reducing E. faecalis within root canals. A total of 81 extracted human mandibular premolar teeth with a single root canal were infected with E. faecalis before and after canal preparation. Samples were divided randomly into 9 groups, as follows: group 1-A: sterile phosphate-buffered saline + Self-adjusting file, group 1-B: 5% sodium hypochlorite + 15% EDTA + Self-adjusting file, group 1-C: 5% sodium hypochlorite + 7% maleic acid + Self-adjusting file, group 2-A: sterile phosphate-buffered saline + Reciproc (R25), group 2-B: 5% sodium hypochlorite + 15% EDTA + Reciproc (R25), group 2-C: 5% sodium hypochlorite + 7% maleic acid + Reciproc (R25), group 3-A: sterile phosphate-buffered saline + ProTaper, group 3-B: 5% sodium hypochlorite + 15% EDTA + ProTaper, group 3-C: 5% sodium hypochlorite + 7% maleic acid + ProTaper. anova was used to analyse statistically the differences in terms of reduction in colony counts between the groups, and Dunn's post hoc test was used for multiple comparisons. All techniques and irrigation regimens significantly reduced the number of bacterial cells in the root canal (P < 0.001). Comparisons amongst the groups revealed significant differences between group 1A (sterile phosphate-buffered saline + Self-adjusting file)/group 1B (5% sodium hypochlorite + 15% EDTA + Self-adjusting file) (P = 0.031), group 1A (sterile phosphate-buffered saline + Self-adjusting file)/group 2C (5% sodium hypochlorite + 7% maleic acid + Reciproc) (P = 0.003), group 2A (sterile phosphate-buffered saline + Reciproc)/group 3B (5% sodium hypochlorite + 15% EDTA + ProTaper) (P = 0.036), group 3B (5% sodium hypochlorite + 15% EDTA + ProTaper)/group 1A (sterile phosphate-buffered saline + Self-adjusting file) (P < 0.001), and group 3C (5% sodium hypochlorite + 7% maleic acid + ProTaper)/group 1A (sterile phosphate-buffered saline + Self-adjusting file) (P = 0.033). No significant differences in terms of reduction in microbial counts were observed between single-file techniques (SAF and Reciproc) and serial Ni-Ti instrumentation technique (ProTaper) in combination with irrigants. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Rapid determination of thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, folic acid and ascorbic acid in Vitamins with Minerals Tablets by high-performance liquid chromatography with diode array detector.

PubMed

Jin, Pengfei; Xia, Lufeng; Li, Zheng; Che, Ning; Zou, Ding; Hu, Xin

2012-11-01

A simple, isocratic, and stability-indicating high-performance liquid chromatography (HPLC) method has been developed for the rapid determination of thiamine (VB(1)), niacinamide (VB(3)), pyridoxine (VB(6)), ascorbic acid (VC), pantothenic acid (VB(5)), riboflavin (VB(2)) and folic acid (VB(9)) in Vitamins with Minerals Tablets (VMT). An Alltima C(18) column (250 mm × 4.6 mm i.d., 5 μm) was used for the separation at ambient temperature, with 50mM ammonium dihydrogen phosphate (adjusting with phosphoric acid to pH 3.0) and acetonitrile as the mobile phase at the flow rate of 0.5 ml min(-1). VB(1), VB(3), VB(6), VC and VB(5) were extracted with a solution containing 0.05% phosphoric acid (v/v) and 0.3% sodium thiosulfate (w/v), and were then simultaneously analyzed by using the mobile phase of phosphate buffer-acetonitrile (95:5, v/v), while VB(2) and VB(9) were extracted with a solution containing 0.5% ammonium hydroxide solution (v/v), and were then simultaneously analyzed by using the mobile phase of phosphate buffer-acetonitrile (85:15, v/v). The detection wavelengths were 275 nm for VB(1), VB(3), VB(6), VC, 210 nm for VB(5), and 282 nm for VB(2) and VB(9). The method showed good system suitability, sensitivity, linearity, specificity, precision, stability and accuracy. All the seven water-soluble vitamins were well separated from other ingredients and degradation products. Method comparison indicated good concordance between the developed method and the USP method. The developed method was reliable and convenient for the rapid determination of VB(1), VB(3), VB(6), VC, VB(5), VB(2) and VB(9) in VMT. Copyright © 2012 Elsevier B.V. All rights reserved.

A time-based potential step analysis of electrochemical impedance incorporating a constant phase element: a study of commercially pure titanium in phosphate buffered saline.

PubMed

Ehrensberger, Mark T; Gilbert, Jeremy L

2010-05-01

The measurement of electrochemical impedance is a valuable tool to assess the electrochemical environment that exists at the surface of metallic biomaterials. This article describes the development and validation of a new technique, potential step impedance analysis (PSIA), to assess the electrochemical impedance of materials whose interface with solution can be modeled as a simplified Randles circuit that is modified with a constant phase element. PSIA is based upon applying a step change in voltage to a working electrode and analyzing the subsequent current transient response in a combined time and frequency domain technique. The solution resistance, polarization resistance, and interfacial capacitance are found directly in the time domain. The experimental current transient is numerically transformed to the frequency domain to determine the constant phase exponent, alpha. This combined time and frequency approach was tested using current transients generated from computer simulations, from resistor-capacitor breadboard circuits, and from commercially pure titanium samples immersed in phosphate buffered saline and polarized at -800 mV or +1000 mV versus Ag/AgCl. It was shown that PSIA calculates equivalent admittance and impedance behavior over this range of potentials when compared to standard electrochemical impedance spectroscopy. This current transient approach characterizes the frequency response of the system without the need for expensive frequency response analyzers or software. Copyright 2009 Wiley Periodicals, Inc.

FACTORS WHICH MODIFY THE EFFECT OF SODIUM AND POTASSIUM ON BACTERIAL CELL MEMBRANES1

PubMed Central

Henneman, Dorothy H.; Umbreit, W. W.

1964-01-01

Henneman, Dorothy H. (Rutgers, The State University, New Brunswick, N.J.), and W. W. Umbreit. Factors which modify the effect of sodium and potassium on bacterial cell membranes. J. Bacteriol. 87:1266–1273. 1964.—Suspensions of Escherichia coli B, when placed in 0.2 to 0.5 m solutions of NaCl, KCl, or LiCl, show an increased turbidity. With NaCl, this increased turbidity is stable with time; with KCl and LiCl, it is gradually lost. The stability to NaCl with time is due to substances removable from the cell by incubation in phosphate buffer; these materials exist in water washings from such phosphate-incubated cells. PMID:14188701

Influence of Dissolution Media and Presence of Alcohol on the In Vitro Performance of Pharmaceutical Products Containing an Insoluble Drug.

PubMed

Friuli, Valeria; Bruni, Giovanna; Musitelli, Giorgio; Conte, Ubaldo; Maggi, Lauretta

2018-01-01

The purpose of this investigation is to determine how the dissolution media may influence the release rate of an insoluble drug in in vitro conditions. Some oral dosage forms containing ibuprofen, a molecule that shows pH-dependent solubility, are tested. They are evaluated in different media to simulate the gastrointestinal transit at paddle rotation speeds of 50 and 100 rpm. Moreover, the potential effect of different ethanol concentrations on drug release is tested. The dissolution profiles of the tablets show a similar behavior in water (pH 1.0) and phosphate buffer (pH 4.5) where the 2 doses are not completely dissolved. The soft capsules show a different behavior: a certain amount of ibuprofen, which is in solution inside the capsule, reprecipitates in water and in the pH 4.5 buffer. Instead, ibuprofen dissolves rapidly in the pH 6.8 buffer from all the formulations. In the water-ethanol solutions, the dissolution curves show a valuable increase in the drug dissolved at higher ethanol concentrations. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

[Determination of total mass and morphology analysis of heavy metal in soil with potassium biphthalate-sodium hydroxide by ICP-AES].

PubMed

Qu, Jiao; Yuan, Xing; Cong, Qiao; Wang, Shuang

2008-11-01

Blank soil was used as quality controlling samples, soil sample dealt by potassium biphthalate-sodium hydroxide buffer solution was used as check sample, mixed acid HNO3-HF-HClO4 was chosen to nitrify soil samples, and plasma emission spectrometer (ICP-AES) was used as detecting method. The authors determined the total metal mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the extracted and dealt soil samples, and determined the mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the three chemical morphologies, including acid extractable morphology, oxide associated morphology, and organics associated modality. The experimental results indicated that the different pH of potassium biphthalate-sodium hydroxide buffer solution had obvious influence on the total mass of heavy metal and morphology transformation. Except for metal element Pb and Zn, the addition of different pH potassium dihydrogen phosphate-sodium hydroxide buffer solution could accelerate the soil samples nitrification and the total mass determination of heavy metal in the soil samples. The potassium biphthalate-sodium hydroxide buffer solution could facilitate the acid extractable morphology of Cr, Cu, Hg and Pb, oxidation associated morphology of As, Hg, Pb and Zn and the organic associated morphology transforming of As and Hg. At pH 5.8, the maximum acid extractable morphology contents of Cu and Hg were 2.180 and 0.632 mg x kg(-1), respectively; at pH 6.2, the maximal oxidation associated morphology content of Pb could achieve 27.792 mg x kg(-1); at pH 6.0, the maximum organic associated morphology content of heavy metal Hg was 4.715 mg x kg(-1).

The use of physiological solutions or media in calcium phosphate synthesis and processing.

PubMed

Tas, A Cuneyt

2014-05-01

This review examined the literature to spot uses, if any, of physiological solutions/media for the in situ synthesis of calcium phosphates (CaP) under processing conditions (i.e. temperature, pH, concentration of inorganic ions present in media) mimicking those prevalent in the human hard tissue environments. There happens to be a variety of aqueous solutions or media developed for different purposes; sometimes they have been named as physiological saline, isotonic solution, cell culture solution, metastable CaP solution, supersaturated calcification solution, simulated body fluid or even dialysate solution (for dialysis patients). Most of the time such solutions were not used as the aqueous medium to perform the biomimetic synthesis of calcium phosphates, and their use was usually limited to the in vitro testing of synthetic biomaterials. This review illustrates that only a limited number of research studies used physiological solutions or media such as Earle's balanced salt solution, Bachra et al. solutions or Tris-buffered simulated body fluid solution containing 27mM HCO3(-) for synthesizing CaP, and these studies have consistently reported the formation of X-ray-amorphous CaP nanopowders instead of Ap-CaP or stoichiometric hydroxyapatite (HA, Ca10(PO4)6(OH)2) at 37°C and pH 7.4. By relying on the published articles, this review highlights the significance of the use of aqueous solutions containing 0.8-1.5 mMMg(2+), 22-27mM HCO3(-), 142-145mM Na(+), 5-5.8mM K(+), 103-133mM Cl(-), 1.8-3.75mM Ca(2+), and 0.8-1.67mM HPO4(2-), which essentially mimic the composition and the overall ionic strength of the human extracellular fluid (ECF), in forming the nanospheres of X-ray-amorphous CaP. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Calcium phosphate/chitosan composite coating: Effect of different concentrations of Mg2+ in the m-SBF on its bioactivity

NASA Astrophysics Data System (ADS)

Zhang, Jie; Dai, Changsong; Wei, Jie; Wen, Zhaohui; Zhang, Shujuan; Lin, Lemin

2013-09-01

The purpose of this study was to investigate the effect of different concentration of Mg2+ in a modified simulated body fluid (m-SBF) on the bioactivity of calcium phosphate/chitosan composite coating. Calcium phosphate/chitosan composite coating was prepared on graphite substrate via electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). The obtained samples were soaked in the m-SBF containing different concentration of Mg2+ for different times. And then, the composite coatings were assessed using X-ray diffractometer (XRD), Fourier-transformed infrared spectroscopy (FTIR), Raman spectra, and scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS). The soaking solution was evaluated by inductively coupled plasma optical emission spectrometer (ICP-OES) test. The analytical results showed that hydroxyapatite (HA) and bone-like apatite (HCA) grew on the surface of calcium phosphate/chitosan composite coating after incubation in different m-SBF. With Mg2+ concentration in m-SBF increased from 1× Mg to 10× Mg, HA in the composite coating first presented a dissolving process and then a precipitating one slowly, while HCA presented a growing trend, continuously. The increasing of Mg2+ concentration in the m-SBF inhibited the total growing process of HA and HCA as a whole. The structure of the composite coating changed from spherical into irregular morphology with the concentration of Mg2+ increasing from 1× Mg to 10× Mg. Over all, with the Mg2+ concentration increasing, the bioactivity of calcium phosphate/chitosan composite coating tended to decrease.

Structure-Function Relationship of Hydrophiidae Postsynaptic Neurotoxins

DTIC Science & Technology

1990-09-18

24 hr. Buffer F consisted of 10 mM sodium phosphate, pH 7.5. containing 0.02% (w/v) lauryl sulfate (SDS), and 0.04% (w/v) sodium cholate. The...subjected to gel filtration on Sephadex G-50-50 using 10 mM sodium phosphate buffer (pH 6.5) containing 0.1 M NaCl. Samples were dissolved in 3.5 ml buffer...sequencing. Isolation of Cobrotoxin. The venom from NaJa naia atra was subjected to Sephadex G50-50 gel filtration pre-equilibrated with 10 mM sodium

A segmental chronic pain syndrome in rats associated with intrathecal infusion of NMDA: evidence for selective action in the dorsal horn.

PubMed

Zochodne, D W; Murray, M; Nag, S; Riopelle, R J

1994-02-01

We explored the effects of chronic lumbar intrathecal NMDA infusion (mini-osmotic pumps) in Sprague-Dawley rats on motor and sensory axon integrity. Several different infusion protocols, each given over a 4 week period were examined: 0.15 M NMDA in phosphate buffered saline; phosphate buffered saline without NMDA; and 0.20 M magnesium sulfate plus 0.15 M NMDA; 0.35 M NMDA. In two additional protocols, 0.15 M NMDA or phosphate buffered saline were infused for a total of 8 weeks. Within 1-2 weeks of the onset of NMDA, but not phosphate buffered saline infusions, the rats exhibited irritability, circling, biting and excessive grooming resulting in loss of hair, and skin ulcerations from autotomy localized to lumbar and sacral innervated dermatomes. Co-infusion of NMDA with magnesium sulfate almost completely prevented these findings. The behavioural changes were not associated with abnormalities of sensory or motor conduction. Intrathecal infusion of NMDA induces a chronic "central" experimental pain disorder in rats, localized to the cord segment with the greatest exposure to the infusion, without involvement of peripheral sensory axons and sparing the axonal integrity of anterior horn cells.

Effectivity of fluoride treatment on hydrogen and corrosion product generation in temporal implants for different magnesium alloys.

PubMed

Trinidad, Javier; Arruebarrena, Gurutze; Marco, Iñigo; Hurtado, Iñaki; Sáenz de Argandoña, Eneko

2013-12-01

The increasing interest on magnesium alloys relies on their biocompatibility, bioabsorbility and especially on their mechanical properties. Due to these characteristics, magnesium alloys are becoming a promising solution to be used, as temporary implants. However, magnesium alloys must overcome their poor corrosion resistance. This article analyses the corrosion behaviour in phosphate-buffered saline solution of three commercial magnesium alloys (AZ31B, WE43 and ZM21) as well as the influence of fluoride treatment on their corrosion behaviour. It is shown that the corrosion rate of all the alloys is decreased by fluoride treatment. However, fluoride treatment affects each alloy differently.

In vitro dynamic swelling behaviors of radiation synthesized polyacrylamide with crosslinkers in the simulated physiological body fluids

NASA Astrophysics Data System (ADS)

Saraydın, Dursun; Işıkver, Yasemin; Karadağ, Erdener; Sahiner, Nurettin; Güven, Olgun

2002-03-01

Acrylamide hydrogels, containing different amounts and types of crosslinkers, were synthesized via γ-irradiation technique. Their swellings in simulated body fluids, such as physiological saline (0.89% NaCl) isoosmotic phosphate buffer at pH 7.4, gastric fluid at pH 1.1 (glycine-HCl), protein (aqueous solution of bovine serum albumin), urine (aqueous solution of urea), glucose and distilled water, were studied. Equilibrium swellings of the hydrogels were changed in the range 27-85 depending upon the fluids, type and amount of crosslinkers. The diffusion exponents were found over half for all hydrogels.

Separation of 2-aminobenzoic acid-derivatized glycosaminoglycans and asparagine-linked glycans by capillary electrophoresis.

PubMed

Sato, Kae; Sato, Kiichi; Okubo, Akira; Yamazaki, Sunao

2005-01-01

A capillary electrophoresis method was developed for the analysis of oligosaccharides combined with derivatization with 2-aminobenzoic acid. Glycosaminoglycan delta-disaccharides were effectively resolved on a fused-silica capillary tube using 150 mM borate, pH 8.5, as a running electrolyte solution. This analytical method was applied to the identification of glycosaminoglycan in combination with enzymatic digestion. The separation of N-glycans or glucose-oligomers was performed with a phosphate buffer containing polyethylene glycol or borate as an electrolyte solution. This method is expected to be useful in the determination of oligosaccharide structures in a glycoprotein.

Instantaneous radioiodination of rose bengal at room temperature and a cold-kit therefor. [DOE patent application

DOEpatents

O'Brien, H. Jr.; Hupf, H.B.; Wanek, P.M.

The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free /sup 125/I/sup -/ is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

Biocompatible Zr-Al-Fe bulk metallic glasses with large plasticity

NASA Astrophysics Data System (ADS)

Hua, NengBin; Li, Ran; Wang, JianFeng; Zhang, Tao

2012-09-01

In the present study, high-zirconium ternary Zr-Al-Fe bulk metallic glasses (BMGs) with low Young's modulus and good plasticity were developed. Zr75Al7.5Fe17.5 BMG exhibits a low Young's modulus of 70 GPa and high Poisson's ratio of 0.403. Pronounced plasticity was demonstrated under both compression and bending conditions for the BMGs. Furthermore, the alloys show high corrosion resistance in phosphate buffered solution. The combination of desirable mechanical and chemical properties implies potential for biomedical applications.

Instantaneous radioiodination of rose bengal at room temperature and a cold kit therefor

DOEpatents

O'Brien, Jr., Harold A.; Hupf, Homer B.; Wanek, Philip M.

1981-01-01

The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free .sup.125 I.sup.- is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

Application of hanging drop technique to optimize human IgG formulations.

PubMed

Li, Guohua; Kasha, Purna C; Late, Sameer; Banga, Ajay K

2010-01-01

The purpose of this work is to assess the hanging drop technique in screening excipients to develop optimal formulations for human immunoglobulin G (IgG). A microdrop of human IgG and test solution hanging from a cover slide and undergoing vapour diffusion was monitored by a stereomicroscope. Aqueous solutions of IgG in the presence of different pH, salt concentrations and excipients were prepared and characterized. Low concentration of either sodium/potassium phosphate or McIlvaine buffer favoured the solubility of IgG. Addition of sucrose favoured the stability of this antibody while addition of NaCl caused more aggregation. Antimicrobial preservatives were also screened and a complex effect at different buffer conditions was observed. Dynamic light scattering, differential scanning calorimetry and size exclusion chromatography studies were performed to further validate the results. In conclusion, hanging drop is a very easy and effective approach to screen protein formulations in the early stage of formulation development.

Aspartic acid incorporated monolithic columns for affinity glycoprotein purification.

PubMed

Armutcu, Canan; Bereli, Nilay; Bayram, Engin; Uzun, Lokman; Say, Rıdvan; Denizli, Adil

2014-02-01

Novel aspartic acid incorporated monolithic columns were prepared to efficiently affinity purify immunoglobulin G (IgG) from human plasma. The monolithic columns were synthesised in a stainless steel HPLC column (20 cm × 5 mm id) by in situ bulk polymerisation of N-methacryloyl-L-aspartic acid (MAAsp), a polymerisable derivative of L-aspartic acid, and 2-hydroxyethyl methacrylate (HEMA). Monolithic columns [poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid) (PHEMAsp)] were characterised by swelling studies, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The monolithic columns were used for IgG adsorption/desorption from aqueous solutions and human plasma. The IgG adsorption depended on the buffer type, and the maximum IgG adsorption from aqueous solution in phosphate buffer was 0.085 mg/g at pH 6.0. The monolithic columns allowed for one-step IgG purification with a negligible capacity decrease after ten adsorption-desorption cycles. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of solutions treated with oxygen radicals in neutral pH region on inactivation of microorganism

NASA Astrophysics Data System (ADS)

Kobayashi, Tsuyoshi; Hashizume, Hiroshi; Ohta, Takayuki; Ishikawa, Kenji; Hori, Masaru; Ito, Masafumi

2015-09-01

The inactivation of microorganisms using nonequilbrium atmospheric pressure plasmas has been attracted much attention due to the low temperature processing and high speed treatment. In this study, we have inactivated E. coli suspended in solutions with neutral pH using an atmospheric-pressure oxygen radical source which can selectively supply electrically neutral oxygen radicals. E. coli cells were suspended with deionized distilled water (DDW) (pH = 6.8) or phosphate buffered saline (PBS) (pH = 7.4) or Citrate-Na buffer (pH = 6.5). The treated samples were diluted and spread on nutrient agar (Nutrient Broth). They were cultured at 37° C. The inactivation effects of oxygen radicals on those cells in solutions were evaluated by colony-counting method. O2 diluted by Ar gas were employed as a working gas for the radical source. The total gas flow rate and the gas mixture ratio of O2/(Ar + O2) were set at 5 slm and 0.6%, respectively. The distance between the radical exit and the suspension surface were set at 10 mm. As a result, the D values for DDW(pH = 6.8), PBS(pH = 7.4) and Citrate-Na buffer(pH = 6.5) were estimated to be 1.4 min, 0.9 min and 16.8 min respectively. The inactivation rates in DDW, PBS were significantly different from that in Citrate-Na buffer. This work was partly supported by JSPS KAKENHI Grant Number 26286072 and project for promoting Research Center in Meijo University.

A relay identification fluorescence probe for Fe3 + and phosphate anion and its applications

NASA Astrophysics Data System (ADS)

Tang, Xu; Wang, Yun; Han, Juan; Ni, Liang; Wang, Lei; Li, Longhua; Zhang, Huiqin; Li, Cheng; Li, Jing; Li, Haoran

2018-02-01

A simple relay identification fluorescence probe for Fe3 + and phosphate anion with ;on-off-on; switching was designed and synthesized based on the phenylthiazole and biphenylcarbonitrile. Probe 1 displayed highly selective and sensitive recognition to Fe3 + in HEPES aqueous buffer (EtOH/H2O = 2:8, v/v, pH = 7.4) solutions. The optimized structures and HOMO and LUMO of probe 1 and [1-Fe3 +] complex were obtained by the density functional theory (DFT) calculations with B3LYP as the exchange and correlation functional using a suite of Gaussian 09 programs. The [1-Fe3 +] complex solution also showed a high selectivity toward PO43 -. The lower limits of detection of probe 1 to Fe3 + and [1-Fe3 +] complex to PO43 - were estimated to 1.09 × 10- 7 M and 1.86 × 10- 7 M. Besides, the probe 1 also was used to detected the target ions in real water sample and living cells successfully.

Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution.

PubMed

Yasuzawa, Mikito; Omura, Yuya; Hiura, Kentaro; Li, Jiang; Fuchiwaki, Yusuke; Tanaka, Masato

2015-01-01

Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface of a platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40°C. The obtained electrode provided a glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for a few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.

Tris-sucrose buffer system: a new specially designed medium for extracellular invertase production by immobilized cells of isolated yeast Cryptococcus laurentii MT-61.

PubMed

Aydogan, Mehmet Nuri; Taskin, Mesut; Canli, Ozden; Arslan, Nazli Pinar; Ortucu, Serkan

2014-01-01

The aims of the present study were to isolate new yeasts with high extracellular (exo) invertase activity and to investigate the usability of buffer systems as invertase production media by immobilized yeast cells. Among 70 yeast isolates, Cryptococcus laurentii MT-61 had the highest exo-invertase activity. Immobilization of yeast cells was performed using sodium alginate. Higher exo-invertase activity for immobilized cells was achieved in tris-sucrose buffer system (TSBS) compared to sodium acetate buffer system and potassium phosphate buffer system. TSBS was prepared by dissolving 30 g of sucrose in 1 L of tris buffer solution. The optimum pH, temperature, and incubation time for invertase production with immobilized cells were determined as 8.0, 35 °C and 36 h in TSBS, respectively. Under optimized conditions, maximum exo-invertase activity was found to be 28.4 U/mL in sterile and nonsterile TSBS. Immobilized cells could be reused in 14 and 12 successive cycles in sterile and nonsterile TSBS without any loss in the maximum invertase activity, respectively. This is the first report which showed that immobilized microbial cells could be used as a biocatalyst for exo-invertase production in buffer system. As an additional contribution, a new yeast strain with high invertase activity was isolated.

Electrohydrodynamic distortion of sample streams in continuous flow electrophoresis

NASA Technical Reports Server (NTRS)

Rhodes, Percy H.; Snyder, Robert S.; Roberts, Glyn O.

1989-01-01

Continuous flow electrophoresis experiments were carried out, using an electrolyte and a sample both made of aqueous solutions of phosphate buffer (with polystyrene latex added for visibility), to investigate causes of the sample spreading in this procedure. It is shown theoretically that an electric field perpendicular to a circular filament of conducting fluid surrounded by a fluid of different conductivity produces an electrohydrodynamic flow, which distorts the filament into an ellipse. Experimental results were found to be fully consistent with theretical predictions. It was found that the rate of distortion of the sample stream into a ribbon was proportional to the square of the applied voltage gradient. Furthermore, the orientation of the ribbon depends on the ratios of dielectric constant and electrical conductivity between the buffer and the sample.

Changes in composition and enamel demineralization inhibition activities of gallic acid at different pH values.

PubMed

Zhang, Jingyang; Huang, Xuelian; Huang, Shengbin; Deng, Meng; Xie, Xincheng; Liu, Mingdong; Liu, Hongling; Zhou, Xuedong; Li, Jiyao; Ten Cate, Jacob Martien

2015-01-01

Gallic acid (GA) has been shown to inhibit demineralization and enhance remineralization of enamel; however, GA solution is highly acidic. This study was to investigate the stability of GA solutions at various pH and to examine the resultant effects on enamel demineralization. The stability of GA in H2O or in phosphate buffer at pH 5.5, pH 7.0 and pH 10.0 was evaluated qualitatively by ultraviolet absorption spectra and quantified by high performance liquid chromatography with diode array detection (HPLC-DAD). Then, bovine enamel blocks were subjected to a pH-cycling regime of 12 cycles. Each cycle included 5 min applications with one of the following treatments: 1 g/L NaF (positive control), 4 g/L GA in H2O or buffered at pH 5.5, pH 7.0 and pH 10.0 and buffers without GA at the same pH (negative control), followed by a 60 min application with pH 5.0 acidic buffers and a 5 min application with neutral buffers. The acidic buffers were analysed for dissolved calcium. GA was stable in pure water and acidic condition, but was unstable in neutral and alkaline conditions, in which ultraviolet spectra changed and HPLC-DAD analysis revealed that most of the GA was degraded. All the GA groups significantly inhibited demineralization (p < 0.05) and there was no significant difference of the inhibition efficacy among different GA groups (p > 0.05). GA could inhibit enamel demineralization and the inhibition effect is not influenced by pH. GA could be a useful source as an anti-cariogenic agent for broad practical application.

Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy.

PubMed

Bradshaw, J G; Peeler, J T; Twedt, R M

1977-09-01

The thermal resistance of spore crops produced from each of two ileal loop-reactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two- to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators.

Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy.

PubMed Central

Bradshaw, J G; Peeler, J T; Twedt, R M

1977-01-01

The thermal resistance of spore crops produced from each of two ileal loop-reactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two- to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators. PMID:199113

Soil solution phosphorus turnover: derivation, interpretation, and insights from a global compilation of isotope exchange kinetic studies

NASA Astrophysics Data System (ADS)

Helfenstein, Julian; Jegminat, Jannes; McLaren, Timothy I.; Frossard, Emmanuel

2018-01-01

The exchange rate of inorganic phosphorus (P) between the soil solution and solid phase, also known as soil solution P turnover, is essential for describing the kinetics of bioavailable P. While soil solution P turnover (Km) can be determined by tracing radioisotopes in a soil-solution system, few studies have done so. We believe that this is due to a lack of understanding on how to derive Km from isotopic exchange kinetic (IEK) experiments, a common form of radioisotope dilution study. Here, we provide a derivation of calculating Km using parameters obtained from IEK experiments. We then calculated Km for 217 soils from published IEK experiments in terrestrial ecosystems, and also that of 18 long-term P fertilizer field experiments. Analysis of the global compilation data set revealed a negative relationship between concentrations of soil solution P and Km. Furthermore, Km buffered isotopically exchangeable P in soils with low concentrations of soil solution P. This finding was supported by an analysis of long-term P fertilizer field experiments, which revealed a negative relationship between Km and phosphate-buffering capacity. Our study highlights the importance of calculating Km for understanding the kinetics of P between the soil solid and solution phases where it is bioavailable. We argue that our derivation can also be used to calculate soil solution turnover of other environmentally relevant and strongly sorbing elements that can be traced with radioisotopes, such as zinc, cadmium, nickel, arsenic, and uranium.

Corneal protection with high-molecular-weight hyaluronan against in vitro and in vivo sodium lauryl sulfate-induced toxic effects.

PubMed

Pauloin, Thierry; Dutot, Mélody; Liang, Hong; Chavinier, Emilie; Warnet, Jean-Michel; Rat, Patrice

2009-10-01

The aim of this study was to investigate high-molecular-weight hyaluronan (HA-HMW) corneal protection against sodium lauryl sulfate (SLS)-induced toxic effects with in vitro and in vivo experimental approaches. In vitro experiments consisted of a human corneal epithelial cell line incubated with HA-HMW, rinsed, and incubated with SLS. Cell viability, oxidative stress, chromatin condensation, caspase-3, -8, -9, and P2X7 cell death receptor activation, interleukin-6, and interleukin-8 production were investigated. In vivo experiments consisted of 36 New Zealand white rabbits treated for 3 days, 3 times per day, with HA-HMW or phosphate-buffered salt solution. At day 4, eyes were treated with SLS. Clinical observation and in vivo confocal microscopy using the Rostock Cornea Module of the Heidelberg Retina Tomograph-II were performed to evaluate and to compare SLS-induced toxicity between eyes treated with HA-HMW and eyes treated with phosphate-buffered salt solution. In vitro data indicate that exposure of human corneal epithelial cells to HA-HMW significantly decreased SLS-induced oxidative stress, apoptosis, and inflammation cytokine production. In vivo data indicate that SLS cornea injuries, characterized by damaged corneal epithelium, damaged anterior stroma, and inflammatory infiltrations, were attenuated with HA-HMW treatment. A good correlation was seen between in vitro and in vivo findings showing that HA-HMW decreases SLS-induced toxic effects and protects cornea.

The characterisation and design improvement of a paper-based E.coli impedimetric sensor

NASA Astrophysics Data System (ADS)

Bezuidenhout, P.; Kumar, S.; Wiederoder, M.; Schoeman, J.; Land, K.; Joubert, T.-H.

2016-02-01

This paper describes the development and optimisation of a paper-based E. coli impedimetric biosensor for water quality monitoring. Impedimetric biosensing is advantageous because it is a highly sensitive, label-free, real-time method for the detection of biological species. An impedimetric biosensor measures the change in impedance caused by specific capture of a target on the sensor surface. Each biosensor consists of a pair of photo paper-based inkjet printed electrodes. An impedance analyser was used to measure the impedance at frequencies ranging from 1 kHz to 1 MHz at 1V. The parameters that were investigated to achieve enhanced sensor performance were buffer type, antibody attachment method, measurement frequency, electrode layout, and conductive material. A 0.04M PBS (phosphate buffered saline) solution achieves better results compared to a less conductive 0.04M PB (potassium phosphate dibasic) solution. The direct adsorption of anti-E. coli antibodies onto the sensor surface yielded better results than attaching the sensor to a lateral flow test. The resistive component had a greater impact on the detected impedance, therefore an optimal frequency of 1 MHz was identified. Geometrical electrode designs that maximise the resistive change between the electrodes were utilised. Both lower cost silver and bio-compatible gold ink were validated as electrode materials. The impedance change generated by the selective capture of E. coli K-12, ranging in concentration from 103 to 107 colony forming units per millilitre (cfu/ml), showed a detection limit of 105 cfu/ml.

Triple Antibiotic Polymer Nanofibers for Intracanal Drug Delivery: Effects on Dual Species Biofilm and Cell Function

PubMed Central

Pankajakshan, Divya; Albuquerque, Maria T.P.; Evans, Joshua D.; Kamocka, Malgorzata M.; Gregory, Richard L.; Bottino, Marco C.

2016-01-01

Introduction Root canal disinfection and the establishment of an intracanal microenvironment conducive to the proliferation/differentiation of stem cells play a significant role in regenerative endodontics. This study was designed to (1) investigate the antimicrobial efficacy of triple antibiotic–containing nanofibers against a dual-species biofilm and (2) evaluate the ability of dental pulp stem cells (DPSCs) to adhere to and proliferate on dentin upon nanofiber exposure. Methods Seven-day-old dual-species biofilm established on dentin specimens was exposed for 3 days to the following: saline (control), antibiotic-free nanofibers (control), and triple antibiotic–containing nanofibers or a saturated triple antibiotic paste (TAP) solution (50 mg/mL in phosphate buffer solution). Bacterial viability was assessed using the LIVE/DEAD assay (Molecular Probes, Inc, Eugene, OR) and confocal laser scanning microscopy. For cyto-compatibility studies, dentin specimens after nanofiber or TAP (1 g/mL in phosphate buffer solution) exposure were evaluated for cell adhesion and spreading by actin-phalloidin staining. DPSC proliferation was assessed on days 1, 3, and 7. Statistics were performed, and significance was set at the 5% level. Results Confocal laser scanning microscopy showed significant bacterial death upon antibiotic-containing nanofiber exposure, differing significantly (P < .05) from antibiotic-free fibers and the control (saline). DPSCs showed enhanced adhesion/spreading on dentin specimens treated with antibiotic-containing nanofibers when compared with its TAP counterparts. The DPSC proliferation rate was similar on days 1 and 3 in antibiotic-free nanofibers, triple antibiotic–containing nanofibers, and TAP-treated dentin. Proliferation was higher (9-fold) on dentin treated with antibiotic-containing nanofibers on day 7 compared with TAP. Conclusions Triple antibiotic–containing polymer nanofibers led to significant bacterial death, whereas they did not affect DPSC attachment and proliferation on dentin. PMID:27663615

Biocorrosion Evaluation on a Zr-Cu-Ag-Ti Metallic Glass

NASA Astrophysics Data System (ADS)

Kumar, Shresh; Anwar, Rebin; Ryu, Wookha; Park, E. S.; Vincent, S.

2018-04-01

Metallic glasses are in high demand for fabrication of variety of innovative products, in particular surgical and biomedical tools and devices owing to its excellent biocompatible properties. In the present investigation, a novel Zr39.5Cu50.5Ag4Ti6 metallic glass composition was synthesized using melt spinning technique. Potentiodynamic polarization studies were conducted to investigate bio-corrosion behaviour of Zr39.5Cu50.5Ag4Ti6 metallic glass. The test were conducted in various simulated artificial body conditions such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution. The bio-corrosion results of metallic glass were compared with traditional biomaterials. The study aims to provide bio-compatible properties of Zr39.5Cu50.5Ag4Ti6 metallic glass.

Formation and Properties of Multilayer Films Based on Polyethyleneimine and Bovine Serum Albumin

NASA Astrophysics Data System (ADS)

Kulikouskaya, V. I.; Lazouskaya, M. E.; Kraskouski, A. N.; Agabekov, V. E.

2018-01-01

(Polyethyleneimine/bovine serum albumin) n ((PEI/BSA) n) multilayer films ( n = 1-10) are produced via the layer-by-later deposition of polyelectrolytes. It is shown that thickness and morphology of the formed coatings can be controlled by varying the solution's ionic strength during alternating adsorption of the components. (PEI/BSA)10 multilayer systems that contain up to 0.6 mg of antiseptic miramistin per 1 cm2 of film were created. It is established that the kinetics of miramistin release from (PEI/BSA)10 films in phosphate buffers and physiological solutions obey the Korsmeyer-Peppas equation with a high degree of accuracy ( R 2 > 0.95).

Microfluidic and Label-Free Multi-Immunosensors Based on Carbon Nanotube Microelectrodes

NASA Astrophysics Data System (ADS)

Tsujita, Yuichi; Maehashi, Kenzo; Matsumoto, Kazuhiko; Chikae, Miyuki; Takamura, Yuzuru; Tamiya, Eiichi

2009-06-01

We fabricated microfluidic and label-free multi-immunosensors by the integration of carbon nanotube (CNT)-arrayed electrodes and microchannels with pneumatic micropumps made of poly(dimethylsiloxane). In the microfluidic systems, four kinds of sample solutions were transported from each liquid inlet to microchannels using six pneumatic micropumps. As a result, two kinds of antibodies were immobilized onto different CNT electrodes using the microfluidic systems. Next, two kinds of cancer markers, prostate specific antigen and human chorionic gonadotropin in phosphate buffer solution, were simultaneously detected by differential pulse voltammetry. Therefore, microfludic multi-immunosensors based on CNT electrodes and pneumatic micropumps are useful for the development of multiplex hand-held biosensors.

Direct extraction of genomic DNA from maize with aqueous ionic liquid buffer systems for applications in genetically modified organisms analysis.

PubMed

Gonzalez García, Eric; Ressmann, Anna K; Gaertner, Peter; Zirbs, Ronald; Mach, Robert L; Krska, Rudolf; Bica, Katharina; Brunner, Kurt

2014-12-01

To date, the extraction of genomic DNA is considered a bottleneck in the process of genetically modified organisms (GMOs) detection. Conventional DNA isolation methods are associated with long extraction times and multiple pipetting and centrifugation steps, which makes the entire procedure not only tedious and complicated but also prone to sample cross-contamination. In recent times, ionic liquids have emerged as innovative solvents for biomass processing, due to their outstanding properties for dissolution of biomass and biopolymers. In this study, a novel, easily applicable, and time-efficient method for the direct extraction of genomic DNA from biomass based on aqueous-ionic liquid solutions was developed. The straightforward protocol relies on extraction of maize in a 10 % solution of ionic liquids in aqueous phosphate buffer for 5 min at room temperature, followed by a denaturation step at 95 °C for 10 min and a simple filtration to remove residual biopolymers. A set of 22 ionic liquids was tested in a buffer system and 1-ethyl-3-methylimidazolium dimethylphosphate, as well as the environmentally benign choline formate, were identified as ideal candidates. With this strategy, the quality of the genomic DNA extracted was significantly improved and the extraction protocol was notably simplified compared with a well-established method.

Stability of glucose oxidase and catalase adsorbed on variously activated 13X zeolite.

PubMed

Pifferi, P G; Vaccari, A; Ricci, G; Poli, G; Ruggeri, O

1982-10-01

The use of 13X zeolite (0.1-0.4-mm granules), treated with 2N and 0.01N HCI, 0.01M citric acid, 0.1M citric-phosphate buffer (pH 3.6), and in untreated form to adsorb glucose oxidase of fungal origin and microbial catalase was examined. Physicochemical analysis of the support demonstrated that its crystalline structure, greatly altered by the HCl and buffer, could be partially maintained with citric acid. The specific adsorption of the enzymes increased with decreasing pH and proved to be considerable for all the supports. The stability with storage at 25 degrees C is strictly correlated with the titrable acidity of the activated zeolite expressed as meq NaOH/g and with pH value of the activation solution. It proved to be lower than 55 h for both enzymes if adsorbed on zeolite treated with 2N HCl, and 15-fold and 30-fold higher for glucose oxidase and catalase adsorbed, respectively, on zeolite treated with the 0.1M citric-phosphate buffer and 0.01M citric acid. The specific adsorption of glucose oxidase and catalase was, respectively, 1840 U/g at pH 3.0 and 6910 U/g at pH 5.0. Their half-life at 25 degrees C with storage at pH 3.5 for the former and at pH 5.0 for the latter was 800 and 1560 h vs. 40 and 110 h for the corresponding free enzymes.

Measurements of atmospheric nitrous acid and nitric acid

NASA Astrophysics Data System (ADS)

Huang, Gu; Zhou, Xianliang; Deng, Guohong; Qiao, Huancheng; Civerolo, Kevin

A highly sensitive technique for the measurement of atmospheric HONO and HNO 3 is reported. The technique is based on aqueous scrubbing using two coil samplers, followed by conversion of HNO 3 to nitrite, derivatization of nitrite to a highly light-absorbing azo dye with sulfanilamide (SA) and N-(1-naphthyl) ethylenediamine (NED), and high performance liquid chromatography (HPLC) analysis. HNO 3 concentration was obtained by the difference of the two channels. Two scrubbing solutions were used for sampling the two species: a 1-mM phosphate buffer solution (pH 7) for the measurement of HONO and a 180 mM NH 4Cl/NH 3 buffer solution (pH 8.5) for the measurement of HONO+HNO 3. The scrubbing solution flow rate was 0.24 ml min -1 and the gas sampling flow rate was 2 l min -1. HNO 3 in the NH 4Cl/NH 3 buffer solution was quantitatively reduced to nitrite along an on-line 0.8-cm Cd reductor column. Nitrite in both channels was derivatized with 2 mM SA and 0.2 mM NED in 25 mM HCl. Quantitative derivatization was achieved within 5 min at 55°C. The azo dye derivative was then separated from the SA/NED reagent by reversed-phase HPLC and detected with a UV-vis detector at 540 nm. With an on-line SEP-PAK C-18 cartridge for the reagent purification, the method detection limit is estimated to be better than 1 pptv for HONO and about 20 pptv for HNO 3. The sample integration time was about 2 min and the sampling frequency is every 10 min. Data collected in downtown Albany and Whiteface Mountain, NY, are shown as examples of applications of this technique in both urban and remote clean environments.

Opioid Abuse after TBI

DTIC Science & Technology

2015-09-01

hippocampal formation (Paxinos and Watson, 2005). The sections were mounted on 1% gelatin -coated slides and stored at -20°C until further histological... drying at room temperature overnight. Finally, sections were rinsed in xylene (2 times for 5 min) and coverslipped with DPX mounting media (Electron...0.1M phosphate buffered saline (3 x 5 min) and 0.1M phosphate buffer (3 x 5 min) and slides were allowed to dry for one hour before being

Effects of protein and phosphate buffer concentrations on thermal denaturation of lysozyme analyzed by isoconversional method.

PubMed

Cao, X M; Tian, Y; Wang, Z Y; Liu, Y W; Wang, C X

2016-07-03

Thermal denaturation of lysozymes was studied as a function of protein concentration, phosphate buffer concentration, and scan rate using differential scanning calorimetry (DSC), which was then analyzed by the isoconversional method. The results showed that lysozyme thermal denaturation was only slightly affected by the protein concentration and scan rate. When the protein concentration and scan rate increased, the denaturation temperature (Tm) also increased accordingly. On the contrary, the Tm decreased with the increase of phosphate buffer concentration. The denaturation process of lysozymes was accelatated and the thermal stability was reduced with the increase of phosphate concentration. One part of degeneration process was not reversible where the aggregation occurred. The other part was reversible. The apparent activation energy (Ea) was computed by the isoconversional method. It decreased with the increase of the conversion ratio (α). The observed denaturation process could not be described by a simple reaction mechanism. It was not a process involving 2 standard reversible states, but a multi-step process. The new opportunities for investigating the kinetics process of protein denaturation can be supplied by this novel isoconversional method.

Use of Raman microscopy and multivariate data analysis to observe the biomimetic growth of carbonated hydroxyapatite on bioactive glass.

PubMed

Seah, Regina K H; Garland, Marc; Loo, Joachim S C; Widjaja, Effendi

2009-02-15

In the present contribution, the biomimetic growth of carbonated hydroxyapatite (HA) on bioactive glass were investigated by Raman microscopy. Bioactive glass samples were immersed in simulated body fluid (SBF) buffered solution at pH 7.40 up to 17 days at 37 degrees C. Raman microscopy mapping was performed on the bioglass samples immersed in SBF solution for different periods of time. The collected data was then analyzed using the band-target entropy minimization technique to extract the observable pure component Raman spectral information. In this study, the pure component Raman spectra of the precursor amorphous calcium phosphate, transient octacalcium phosphate, and matured HA were all recovered. In addition, pure component Raman spectra of calcite, silica glass, and some organic impurities were also recovered. The resolved pure component spectra were fit to the normalized measured Raman data to provide the spatial distribution of these species on the sample surfaces. The current results show that Raman microscopy and multivariate data analysis provide a sensitive and accurate tool to characterize the surface morphology, as well as to give more specific information on the chemical species present and the phase transformation of phosphate species during the formation of HA on bioactive glass.

Nitric oxide evokes pain in humans on intracutaneous injection.

PubMed

Holthusen, H; Arndt, J O

1994-01-03

To test the hypothesis that nitric oxide (NO) acts algetically in humans, we determined pain intensity/dose relations for intracutaneously applied NO solutions. NO, dissolved in isoosmolar phosphate buffer, was injected in the forearm of six volunteers and the subjects rated NO-evoked pain continuously with the help of an electronically controlled visual analogue scale. Pain always occurred at a NO dose of 12 nmol, increased with dose and reached the tolerance maximum at 50 nmol. This shows for the first time the genuine pain evoking properties of NO.

The decomposition of peroxynitrite to nitroxyl anion (NO−) and singlet oxygen in aqueous solution

PubMed Central

Khan, Ahsan Ullah; Kovacic, Dianne; Kolbanovskiy, Alexander; Desai, Mehul; Frenkel, Krystyna; Geacintov, Nicholas E.

2000-01-01

The mechanism of decomposition of peroxynitrite (OONO−) in aqueous sodium phosphate buffer solution at neutral pH was investigated. The OONO− was synthesized by directly reacting nitric oxide with superoxide anion at pH 13. The hypothesis was explored that OONO−, after protonation at pH 7.0 to HOONO, decomposes into 1O2 and HNO according to a spin-conserved unimolecular mechanism. Small aliquots of the concentrated alkaline OONO− solution were added to a buffer solution (final pH 7.0–7.2), and the formation of 1O2 and NO− in high yields was observed. The 1O2 generated was trapped as the transannular peroxide (DPAO2) of 9,10-diphenylanthracene (DPA) dissolved in carbon tetrachloride. The nitroxyl anion (NO−) formed from HNO (pKa 4.5) was trapped as nitrosylhemoglobin (HbNO) in an aqueous methemoglobin (MetHb) solution. In the presence of 25 mM sodium bicarbonate, which is known to accelerate the rate of decomposition of OONO−, the amount of singlet oxygen trapped was reduced by a factor of ≈2 whereas the yield of trapping of NO− by methemoglobin remained unaffected. Because NO3− is known to be the ultimate decomposition product of OONO−, these results suggest that the nitrate anion is not formed by a direct isomerization of OONO−, but by an indirect route originating from NO−. PMID:10716721

Comparative analyses of universal extraction buffers for assay of stress related biochemical and physiological parameters.

PubMed

Han, Chunyu; Chan, Zhulong; Yang, Fan

2015-01-01

Comparative efficiency of three extraction solutions, including the universal sodium phosphate buffer (USPB), the Tris-HCl buffer (UTHB), and the specific buffers, were compared for assays of soluble protein, free proline, superoxide radical (O2∙-), hydrogen peroxide (H2O2), and the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and glutathione reductase (GR) in Populus deltoide. Significant differences for protein extraction were detected via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2-DE). Between the two universal extraction buffers, the USPB showed higher efficiency for extraction of soluble protein, CAT, GR, O2∙-, GPX, SOD, and free proline, while the UTHB had higher efficiency for extraction of APX, POD, and H2O2. When compared with the specific buffers, the USPB showed higher extraction efficiency for measurement of soluble protein, CAT, GR, and O2∙-, parallel extraction efficiency for GPX, SOD, free proline, and H2O2, and lower extraction efficiency for APX and POD, whereas the UTHB had higher extraction efficiency for measurement of POD and H2O2. Further comparisons proved that 100 mM USPB buffer showed the highest extraction efficiencies. These results indicated that USPB would be suitable and efficient for extraction of soluble protein, CAT, GR, GPX, SOD, H2O2, O2∙-, and free proline.

In vitro dissolution and in vivo gamma scintigraphic evaluation of press-coated salbutamol sulfate tablets.

PubMed

Li, Wei; Shi, Cai-Hong; Sheng, Yi-Ling; Cui, Ping; Zhao, Yu-Qing; Zhang, Xiang-Rong

2013-12-01

The aim of this study was to investigate the in vitro and in vivo performance of salbutamol sulfate press-coated tablets for delayed release. The in vitro release behavior of press-coated tablets with the outer layer of PEG 6000/ Eudragit S100 blends (2:1) in pH 1.2 (0.1 mol L-1 HCl) and then pH 6.8 buffer solution was examined. Morphological change of the press-coated tablet during in vitro release was recorded with a digital camera. Release of salbutamol sulfate from press-coated tablets was less than 5 % before 3 h and was completed after 8 h in pH 6.8 phosphate buffer solution. In vivo gamma scintigraphy study carried out on healthy men indicated that the designed system released the drug in lower parts of the GI tract after a lag time of 5 hours. The results showed the capability of the system of achieving delayed release of the drug in both in vitro and in vivo gamma scintigraphy studies.

Formate binding near the redox-active tyrosineD in photosystem II: consequences on the properties of tyrD.

PubMed

Hienerwadel, Rainer; Gourion-Arsiquaud, Samuel; Ballottari, Matteo; Bassi, Roberto; Diner, Bruce A; Berthomieu, Catherine

2005-06-01

Formate and phosphate affect substantially the rate of tyrosine D (TyrD) oxidation and the stability of the radical TyrD* in Photosystem II [Hienerwadel R, Boussac A, Breton J and Berthomieu C (1996) Biochemistry 35: 15447-15460]. This observation prompted us to analyze the influence of formate and phosphate on the environment of TyrD using FTIR spectroscopy. The nu (CO) IR mode of TyrD* at 1503 cm-1 remains unchanged whatever the buffer used at pH 6 and whether formate is present or not in the sample. Similarly, the main IR mode of reduced TyrD remains at approximately 1250 cm-1 in all tested conditions. We thus conclude that formate does not modify the hydrogen-bonded interactions of TyrD and TyrD* with neighbouring D2His189 and D2Gln164. In the TyrD-state, an IR mode of formate significantly different from that observed in solution, is detected using 13C-formate, showing that formate forms a strong electrostatic interaction within PS II. The presence of formate affects also IR bands that may be assigned to an arginine side chain. Upon TyrD* formation, formate does not protonate but its binding interaction weakens. A proton uptake by Mes or phosphate buffer is detected, which is not observed when BisTris is used as a buffer. In these latter conditions, IR bands characteristic of the protonation of a carboxylate group of the protein are detected instead. The present IR data and the recent structural model of the TyrD environment proposed by Ferreira KN, Iverson TM, Maghlaoui K, Barber J and Iwata S [(2004) Science 303: 1831-1838], suggest that the proton released upon TyrD* formation is shared within a hydrogen bonding network including D2Arg294, and CP47Glu364 and that perturbation of this network by formate - possibly binding near D2Arg294 - substantially affects the properties of TyrD.

Human serum albumin crystals and method of preparation

NASA Technical Reports Server (NTRS)

Carter, Daniel C. (Inventor)

1989-01-01

Human serum albumin (HSA) crystals are provided in the form of tetragonal plates having the space groups P42(sub 1)2, the crystals being grown to sizes in excess of 0.5 mm in two dimensions and a thickness of 0.1 mm. Growth of the crystals is carried out by a hanging drop method wherein a precipitant solution containing polyethylene glycol (PEG) and a phosphate buffer is mixed with an HSA solution, and a droplet of mixed solution is suspended over a well of precipitant solution. Crystals grow to the desired size in 3 to 7 days. Concentration of reagents, pH and other parameters are controlled within prescribed limits. The resulting crystals exhibit a size and quality such as to allow performance of x ray diffraction studies and enable the conduct of drug binding studies as well as genetic engineering studies.

Determination of chloramphenicol and zeranols in pig muscle by immunoaffinity column clean-up and LC-MS/MS analysis.

PubMed

Wang, Qing; Zhao, Hua; Xi, Cunxian; Wang, Guomin; Chen, Dongdong; Ding, Shijia

2014-01-01

An immunoaffinity column clean-up and LC-MS/MS method was successfully developed for simultaneous determination of chloramphenicol, zearalanone, α-zearalanol, β-zearalanol, zearalenone, α-zearalenol and β-zearalenol in pig muscle. The sample was extracted with diethyl ether after enzymatic digestion by β-glucuronidase/sulfatase. The extracted solution was evaporated to dryness and the residue was then dissolved in 1 ml of 50% acetonitrile solution. After filtration and dilution with phosphate buffer solution (PBS), the reconstituted solution was cleaned-up with an IAC-CZ immunoaffinity column and then analysed by HPLC-MS/MS. The established method were validated by linearity (r ≥ 0.9990), precision (RSD ≥ 2.9%), average recovery (74.5-105.0%) and limit of detection (0.04-0.10 μg kg(-1)). The developed method is rapid, reliable, sensitive, accurate and has good applicability for real samples.

In vitro formation and thermal transition of novel hybrid fibrils from type I fish scale collagen and type I porcine collagen

NASA Astrophysics Data System (ADS)

Chen, Song; Ikoma, Toshiyuki; Ogawa, Nobuhiro; Migita, Satoshi; Kobayashi, Hisatoshi; Hanagata, Nobutaka

2010-06-01

Novel type I collagen hybrid fibrils were fabricated by neutralizing a mixture of type I fish scale collagen solution and type I porcine collagen solution with a phosphate buffer saline at 28 °C. Their structure was discussed in terms of the volume ratio of fish/porcine collagen solution. Scanning electron and atomic force micrographs showed that the diameter of collagen fibrils derived from the collagen mixture was larger than those derived from each collagen, and all resultant fibrils exhibited a typical D-periodic unit of ~67 nm, irrespective of volume ratio of both collagens. Differential scanning calorimetry revealed only one endothermic peak for the fibrils derived from collagen mixture or from each collagen solution, indicating that the resultant collagen fibrils were hybrids of type I fish scale collagen and type I porcine collagen.

40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium, and zinc salts of the phosphate esters; minimum oxyethylene content is 2 moles.... 14433-76-2) Emulsifier, solvent, cosolvent Diammonium phosphate (CAS Reg. No. 7783-28-0) Buffer...

40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium, and zinc salts of the phosphate esters; minimum oxyethylene content is 2 moles... phosphate (CAS Reg. No. 7783-28-0) Buffer, surfactant dibenzylidene sorbitol (32647-67-9) Thinning agent...

40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium, and zinc salts of the phosphate esters; minimum oxyethylene content is 2 moles... phosphate (CAS Reg. No. 7783-28-0) Buffer, surfactant dibenzylidene sorbitol (32647-67-9) Thinning agent...

/sup 3/H)pirenzepine and (-)-(/sup 3/H)quinuclidinyl benzilate binding to rat cerebral cortical and cardiac muscarinic cholinergic sites. I. Characterization and regulation of agonist binding to putative muscarinic subtypes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, M.; Yamamura, H.I.; Roeske, W.R.

The binding and regulation of selected muscarinic agonists to putative subtypes in rat cerebral cortex and heart were studied. Parallel inhibition studies of (/sup 3/H)pirenzepine ((/sup 3/H)PZ) and (-)-(/sup 3/H)quinuclidinylbenzilate ((-)-(/sup 3/H)QNB)-labeled membranes were done with and without 30 microM guanyl-5'-yl imidodiphosphate (Gpp(NH)p) at 25 degrees C in 10 mM Na-K-phosphate buffer which enhances PZ binding affinity and in modified Krebs-phosphate buffer, which mimics physiological conditions. Classical agonists such as carbachol, oxotremorine and acetylcholine inhibited (-)-(/sup 3/H)QNB binding to membranes with shallow Hill values (nH less than 1), were better fit to a 2-state model, were Gpp(NH)p-regulated and showed lowermore » affinity in modified Krebs-phosphate buffer than in 10 mM Na-K-phosphate buffer. Some agonists were not significantly better fit to a 2-state model in (/sup 3/H)PZ-labeled cortical membranes, especially in 10 mM Na-K-phosphate buffer. Whereas putative M1 and M2 binding sites distinguished by PZ possessed multiple agonist affinity states, as judged by carbachol, and agonist binding to (/sup 3/H)PZ-labeled sites were Gpp(NH)p modulated, the partial agonist pilocarpine and nonclassical agonist McN-A-343 (3-(m-chlorophenylcarbamoyloxy)-2-butynyl trimethylammonium chloride) showed little Gpp(NH)p-induced shift in (/sup 3/H)PZ-labeled cortical membranes in physiological conditions. Agonist binding to (-)-(/sup 3/H)QNB-labeled putative M2 cardiac sites was more sensitive to Gpp(NH)p than (-)-(/sup 3/H)QNB-labeled cortical sites. Carbachol and acetylcholine showed significant selectivity for putative M2 sites.« less

Fundamental and Applied Studies of Polymer Membranes

NASA Astrophysics Data System (ADS)

Imbrogno, Joseph

Four major areas have been studied in this research: 1) synthesizing novel monomers, e.g. chiral monomers, to produce new types of functionalized membranes for the biotechnology and pharmaceutical industries, 2) hydrophobic brush membranes for desalinating brackish water, sea water, and separating organics, 3) fundamental studies of water interactions at surfaces using sum frequency generation (SFG), and 4) discovering new surface chemistries that will control the growth and differentiation of stem cells. We have developed a novel synthesis method in order to increase the breadth of our high throughput screening library. This library was generated using maleimide chemistry to react a common methacrylate linker with a variety of different functions groups (R groups) in order to form new monomers that were grafted from the surface of PES ultrafiltration membranes. From this work, we discovered that the chirality of a membrane can affect performance when separating chiral feed streams. This effect was observed when filtering bovine serum albumin (BSA) and ovalbumin in a high salt phosphate buffered saline (PBS, 150 mM salt). The Phe grafted membranes showed a large difference in performance when filtering BSA with selectivity of 1.13 and 1.00 for (S) and (R) Phe, respectively. However, when filtering ovalbumin, the (S) and (R) modified surfaces showed selectivity of 2.06 and 2.31, respectively. The higher selectivity enantiomer switched for the two different proteins. Permeability when filtering BSA was 3.06 LMH kPa-1 and 4.31 LMH kPa -1 for (S)- and (R)- Phe, respectively, and 2.65 LMH kPa -1 and 2.10 LMH kPa-1 when filtering ovalbumin for (S)- and (R)- Phe, respectively. Additionally, these effects were no longer present when using a low salt phosphate buffer (PB, 10 mM salt). Since, to our knowledge, membrane chirality is not considered in current industrial systems, this discovery could have a large impact on the pharmaceutical and biotechnology industries. We have developed hydrophobic brush membranes that were able to selectively separate valuable organics (isobutanol) from water, while rejecting other undesirable species, such as enzymes, using pervaporation (PV). These membranes (grafted from nanofiltration (NF) support membranes) had a selectivity ˜1.5x higher than the current industrial standard, polydimethylsiloxane (PDMS), with alpha = 10.1 +/- 0.9 for our brush membranes and alpha = 6.7 +/- 0.1 for PDMS membranes. Since the mechanism of pervaporation is based on the solution diffusion (SD) model, these membranes may be used to desalinate water or fractionate gases since they are also based on the SD mechanism. We have discovered that hydrophobic brush membranes are able to reject monovalent salt ions. This type of membrane is analogous to carbon nanotubes (CNTs), which are believed to have extremely high water fluxes through them due to near frictionless flow caused by a lack of hydrogen bonding. Using these brush membranes we were able to achieve 42% monovalent (NaCl) salt rejection of simulated seawater (32,000 ppm salt). These membranes are easier to scale-up than current composite membranes produced using interfacial polymerization. We have been using SFG to study interfacial water on membrane surfaces. We believe that water interactions with the membrane surface and with the feed species, e.g. proteins, play a critical role during the fouling process. Relevant buffers, such as phosphate buffered saline (PBS) and phosphate buffer, contain ions that are known to restructure water at interfaces. Sum frequency generation spectroscopy (SFG) was used to characterize interfacial water structure at poly(ether sulfone) (PES) thin films in the presence of 0.01 M phosphate buffer (low salt) and 0.01 M phosphate buffered saline (high salt). Three model surfaces were studied: unmodified PES, hydrophobic alkane (C18) modified PES, and poly(ethylene glycol) (PEG) modified PES. In the presence of the low salt phosphate buffer (10 mM salt), phosphate anions were excluded from the PEG-modified PES film. This led to a charge separation between the phosphate anions and sodium cations, creating a surface potential which strongly ordered water molecules into the bulk. When using high salt PBS (138 mM salt) the sodium chloride ions screened this charge and reduced water ordering. Interestingly, this effect was the greatest for the PEG modified surface, with minor or no effects observed for the C18 modified PES and unmodified PES, respectively. Using our high throughput screening platform, we were able to determine that (N-[3-(dimethylamino)propyl] methacrylamide), DMAPMA, supported strong attachment and long-term self-renewal of mouse embryonic stem (ES) cells while preventing differentiation (maintaining pluripotency). After developing this platform, it was used to screen for a surface that could instead induce differentiation of bovine and human retinal pigment epithelium (RPE) cells while promoting cell growth. Several PEG based surfaces were able to induce cobblestone morphology of the RPE cells, which is indicative of differentiation. (Abstract shortened by UMI.).

Hydrolysis of the quinone methide of butylated hydroxytoluene in aqueous solutions.

PubMed

Willcockson, Maren Gulsrud; Toteva, Maria M; Stella, Valentino J

2013-10-01

Butylated hydroxytoluene or BHT is an antioxidant commonly used in pharmaceutical formulations. BHT upon oxidation forms a quinone methide (QM). QM is a highly reactive electrophilic species that can undergo nucleophilic addition. Here, the kinetic reactivity of QM with water at various apparent pH values in a 50% (v/v) water-acetonitrile solution at constant ionic strength of I = 0.5 (NaCl)4 , was studied. The hydrolysis of QM in the presence of added acid, base, sodium chloride, and phosphate buffer resulted in the formation of only one product--the corresponding 3,5-di-tert-butyl-4-hydroxybenzyl alcohol (BA). The rate of BA formation was catalyzed by the addition of acid and base, but not chloride and phosphate species. Nucleophilic excipients, used in the pharmaceutical formulation, or nucleophilic groups on active pharmaceutical ingredient molecule may form adducts with QM, the immediate oxidative product of BHT degradation, thus having implications for drug product impurity profiles. Because of these considerations, BHT should be used with caution in formulations containing drugs or excipients capable of acting as nucleophiles. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Coatings from blends of Eudragit® RL and L55: a novel approach in pH-controlled drug release.

PubMed

Wulff, R; Leopold, C S

2014-12-10

The aim of the present study was to investigate the drug release from theophylline pellets coated with blends of quaternary polymethacrylate and methacrylic acid-ethyl acrylate copolymers. Pellets were coated with blends of Eudragit(®) RL PO (RL) and Eudragit(®) L 100-55 (L55) in either organic solution or aqueous dispersion at various copolymer ratios. Generally, the coatings were less permeable for theophylline in phosphate buffer pH 6.8 than they were in hydrochloric acid pH 1.2. Further dissolution experiments revealed that the differences in drug release are caused by the different pH values. A design of experiments for historical data was performed on drug release data of pellets with different coating levels and blend ratios of RL and L55. Drug release in hydrochloric acid was predominantly affected by the coating level, whereas for drug release in phosphate buffer pH 6.8 the blend ratio was the determining factor. As expected, dissolution experiments at different pH values showed that drug release depends on the ratio of dissociated L55 to RL because ionization is a requirement for the functional groups to interact. With the dissolution test for delayed-release solid dosage forms (Ph. Eur.) it was demonstrated that the unique release behavior in neutral media is preserved after the exposition to hydrochloric acid. These findings indicate that the combination of RL and L55 in coatings prepared from solutions is a promising approach for controlled drug release. Copyright © 2014 Elsevier B.V. All rights reserved.

Zearalenone reduction by commercial peroxidase enzyme and peroxidases from soybean bran and rice bran.

PubMed

Garcia, Sabrina O; Feltrin, Ana Carla P; Garda-Buffon, Jaqueline

2018-06-11

The peroxidase (POD) enzyme, obtained from different sources, has been described in the literature regarding its good results of reduction in concentration or degradation levels of mycotoxins, such as aflatoxin B1, deoxynivalenol and zearalenone. This study aimed at evaluating the action of commercial peroxidase and peroxidase from soybean bran (SB) and rice bran (RB) in zearalenone (ZEA) reduction in a model solution and the characterization of the mechanism of enzyme action. POD was extracted from SB and RB in phosphate buffer by orbital agitation. Evaluation of the action of commercial POD and POD from SB and RB in ZEA reduction was carried out in phosphate buffer and aqueous solution, respectively. Parameters of K M and V max were determined in the concentration range from 0.16 to 6 µg mL -1 . ZEA reduction was determined and the mechanism of enzyme action was characterized by Fourier transform infrared spectroscopy and high-pressure liquid chromatography-electrospray tandem mass spectrometry. Commercial POD and POD from RB and SB reduced ZEA concentration by 69.9, 47.4 and 30.6% in 24 h, respectively. K M values were 39.61 and 8.90 µM whereas V max values were 0.170 and 0.011 µM min -1 for commercial POD and POD from RB, respectively. The characterization of the mechanism of enzyme action showed the oxidoreductive action of commercial POD in the mycotoxin. The use of commercial POD and POD from agro-industrial by-products, such as SB and RB, could be a promising alternative for ZEA biodegradation.

ELISA (Enzyme-linked Immunosorbent Assay) to Detect Humoral Antibodies Specific for Clostridium botulinum Type A Neurotoxin

DTIC Science & Technology

1985-11-19

10.6). Unbound toxoid was removed by washing three times with phosphate-buffered saline (pH 7.4) containing 0.05% Triton X-100 (Eastman Organic...MD) in phosphate-buffered saline was added. After a 90 min incubation period at 37*C, the excess conjugate was removed by washing each well three times...3. Cardella, M. A. 1964. Botulinum toxoids, p. 113-129. In K . H. Lewis and K . Cassel, Jr., (ed.), Botulism. U. S. Department of Health, Education

Analysis of Fatty Acid and Growth Profiles in Ten Shewanella spp. to Associate Phylogenetic Relationships

DTIC Science & Technology

2015-10-25

in a defined medium composed of half-strength Marine Broth adjusted to pH 6, 7, or 8 in a 50 mM phosphate buffer, both growth characteristics and...work had broad phylogenetic diversity (Fig. 1) and were isolated from mostly marine environments. S. putrefaciens was the only strain that was not...the defined medium that supported growth of most of the strains tested was marine broth diluted to half strength with 50 mM phosphate buffer (½-MB

Innovative Microsystems: Novel Nanostructures to Capture Circulating Breast Cancer Cells

DTIC Science & Technology

2009-05-01

temperature to promote a Schiff-base reaction. Recombinant protein G from E . coli (Zymed Lab Inc.) 50 μg/ml in Ca- and Mg-free phosphate-buffered...recombinant protein G from E . coli (Zymed Lab Inc.), at a concentration of 50 mg ml1 in 1 PBS, is incubated on the activated surface overnight at 4 C...reaction. Recombinant protein G from E . coli (Zymed Lab Inc.) 50 μg/ml in Ca- and Mg-free phosphate-buffered saline (CMF-PBS), is incubated on the

Improved production and processing of ⁸⁹Zr using a solution target.

PubMed

Pandey, Mukesh K; Bansal, Aditya; Engelbrecht, Hendrik P; Byrne, John F; Packard, Alan B; DeGrado, Timothy R

2016-01-01

The objectives of the present work were to improve the cyclotron production yield of (89)Zr using a solution target, develop a practical synthesis of the hydroxamate resin used to process the target, and develop a biocompatible medium for (89)Zr elution from the hydroxamate resin. A new solution target (BMLT-2) with enhanced heat dissipation capabilities was designed by using helium-cooled dual foils (0.2 mm Al and 25 μ Havar) and an enhanced water-cooled, elongated solution cavity in the target insert. Irradiations were performed with 14 MeV protons on a 2M solution of yttrium nitrate in 1.25 M nitric acid at 40-μA beam current for 2 h in a closed system. Zirconium-89 was separated from Y by use of a hydroxamate resin. A one-pot synthesis of hydroxamate resin was accomplished by activating the carboxylate groups on a carboxymethyl cation exchange resin using methyl chloroformate followed by reaction with hydroxylamine hydrochloride. After trapping of (89)Zr on hydroxamate resin and rinsing the resin with HCl and water to release Y, (89)Zr was eluted with 1.2 M K2HPO4/KH2PO4 buffer (pH3.5). ICP-MS was used to measure metal contaminants in the final (89)Zr solution. The BMLT-2 target produced 349±49 MBq (9.4±1.2 mCi) of (89)Zr at the end of irradiation with a specific activity of 1.18±0.79 GBq/μg. The hydroxamate resin prepared using the new synthesis method showed a trapping efficiency of 93% with a 75 mg resin bed and 96-97% with a 100-120 mg resin bed. The elution efficiency of (89)Zr with 1.2M K2HPO4/KH2PO4 solution was found to be 91.7±3.7%, compared to >95% for 1 M oxalic acid. Elution with phosphate buffer gave very small levels of metal contaminants: Al=0.40-0.86 μg (n=2), Fe=1.22±0.71 μg (n=3), Y=0.29 μg (n=1). The BMLT-2 target allowed doubling of the beam current for production of (89)Zr, resulting in a greater than 2-fold increase in production yield in comparison with a conventional liquid target. The new one-pot synthesis of hydroxamate resin provides a simpler synthesis method for the (89)Zr trapping resin. Finally, phosphate buffer elutes the (89)Zrfrom the hydroxamate resin in high efficiency while at the same time providing a more biocompatible medium for subsequent use of (89)Zr. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of protein and phosphate buffer concentrations on thermal denaturation of lysozyme analyzed by isoconversional method

PubMed Central

Cao, X.M.; Tian, Y.; Wang, Z.Y.; Liu, Y.W.; Wang, C.X.

2016-01-01

ABSTRACT Thermal denaturation of lysozymes was studied as a function of protein concentration, phosphate buffer concentration, and scan rate using differential scanning calorimetry (DSC), which was then analyzed by the isoconversional method. The results showed that lysozyme thermal denaturation was only slightly affected by the protein concentration and scan rate. When the protein concentration and scan rate increased, the denaturation temperature (Tm) also increased accordingly. On the contrary, the Tm decreased with the increase of phosphate buffer concentration. The denaturation process of lysozymes was accelatated and the thermal stability was reduced with the increase of phosphate concentration. One part of degeneration process was not reversible where the aggregation occurred. The other part was reversible. The apparent activation energy (Ea) was computed by the isoconversional method. It decreased with the increase of the conversion ratio (α). The observed denaturation process could not be described by a simple reaction mechanism. It was not a process involving 2 standard reversible states, but a multi-step process. The new opportunities for investigating the kinetics process of protein denaturation can be supplied by this novel isoconversional method. PMID:27459596

Comparing human peritoneal fluid and phosphate-buffered saline for drug delivery: do we need bio-relevant media?

PubMed

Bhusal, Prabhat; Rahiri, Jamie Lee; Sua, Bruce; McDonald, Jessica E; Bansal, Mahima; Hanning, Sara; Sharma, Manisha; Chandramouli, Kaushik; Harrison, Jeff; Procter, Georgina; Andrews, Gavin; Jones, David S; Hill, Andrew G; Svirskis, Darren

2018-06-01

An understanding of biological fluids at the site of administration is important to predict the fate of drug delivery systems in vivo. Little is known about peritoneal fluid; therefore, we have investigated this biological fluid and compared it to phosphate-buffered saline, a synthetic media commonly used for in vitro evaluation of intraperitoneal drug delivery systems. Human peritoneal fluid samples were analysed for electrolyte, protein and lipid levels. In addition, physicochemical properties were measured alongside rheological parameters. Significant inter-patient variations were observed with regard to pH (p < 0.001), buffer capacity (p < 0.05), osmolality (p < 0.001) and surface tension (p < 0.05). All the investigated physicochemical properties of peritoneal fluid differed from phosphate-buffered saline (p < 0.001). Rheological examination of peritoneal fluid demonstrated non-Newtonian shear thinning behaviour and predominantly exhibited the characteristics of an entangled network. Inter-patient and inter-day variability in the viscosity of peritoneal fluid was observed. The solubility of the local anaesthetic lidocaine in peritoneal fluid was significantly higher (p < 0.05) when compared to phosphate-buffered saline. Interestingly, the dissolution rate of lidocaine was not significantly different between the synthetic and biological media. Importantly, and with relevance to intraperitoneal drug delivery systems, the sustained release of lidocaine from a thermosensitive gel formulation occurred at a significantly faster rate into peritoneal fluid. Collectively, these data demonstrate the variation between commonly used synthetic media and human peritoneal fluid. The differences in drug release rates observed illustrate the need for bio-relevant media, which ultimately would improve in vitro-in vivo correlation.

Quantitative and qualitative optimization of allergen extraction from peanut and selected tree nuts. Part 2. Optimization of buffer and ionic strength using a full factorial experimental design.

PubMed

L'Hocine, Lamia; Pitre, Mélanie

2016-03-01

A full factorial design was used to assess the single and interactive effects of three non-denaturing aqueous (phosphate, borate, and carbonate) buffers at various ionic strengths (I) on allergen extractability from and immunoglobulin E (IgE) immunoreactivity of peanut, almond, hazelnut, and pistachio. The results indicated that the type and ionic strength of the buffer had different effects on protein recovery from the nuts under study. Substantial differences in protein profiles, abundance, and IgE-binding intensity with different combinations of pH and ionic strength were found. A significant interaction between pH and ionic strength was observed for pistachio and almond. The optimal buffer system conditions, which maximized the IgE-binding efficiency of allergens and provided satisfactory to superior protein recovery yield and profiles, were carbonate buffer at an ionic strength of I=0.075 for peanut, carbonate buffer at I=0.15 for almond, phosphate buffer at I=0.5 for hazelnut, and borate at I=0.15 for pistachio. The buffer type and its ionic strength could be manipulated to achieve the selective solubility of desired allergens. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Novel bufferless photosynthetic microbial fuel cell (PMFCs) for enhanced electrochemical performance.

PubMed

Wang, Chin-Tsan; Huang, Yan-Sian; Sangeetha, Thangavel; Chen, Yen-Ming; Chong, Wen-Tong; Ong, Hwai-Chyuan; Zhao, Feng; Yan, Wei-Mon

2018-05-01

Photosynthetic microbial fuel cells (PMFCs) are novel bioelectrochemical transducers that employ microalgae to generate oxygen, organic metabolites and electrons. Conventional PMFCs employ non-eco-friendly membranes, catalysts and phosphate buffer solution. Eliminating the membrane, buffer and catalyst can make the MFC a practical possibility. Therefore, single chambered (SPMFC) were constructed and operated at different recirculation flow rates (0, 40 and 240 ml/min) under bufferless conditions. Furthermore, maximum power density of 4.06 mW/m 2 , current density of 46.34 mA/m 2 and open circuit potential of 0.43 V and low internal resistance of 611.8 Ω were obtained at 40 ml/min. Based on the results it was decided that SPMFC was better for operation at 40 ml/min. Therefore, these findings provided progressive insights for future pilot and industrial scale studies of PMFCs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions: from protein buffer capacity prediction to bioprocess applications.

PubMed

Bahrenburg, Sven; Karow, Anne R; Garidel, Patrick

2015-04-01

Protein therapeutics, including monoclonal antibodies (mAbs), have significant buffering capacity, particularly at concentrations>50 mg/mL. This report addresses pH-related issues critical to adoption of self-buffered monoclonal antibody formulations. We evaluated solution conditions with protein concentrations ranging from 50 to 250 mg/mL. Samples were both buffer-free and conventionally buffered with citrate. Samples were non-isotonic or adjusted for isotonicity with NaCl or trehalose. Studies included accelerated temperature stability tests, shaking stability studies, and pH changes in infusion media as protein concentrate is added. We present averaged buffering slopes of capacity that can be applied to any mAb and present a general method for calculating buffering capacity of buffer-free, highly concentrated antibody liquid formulations. In temperature stability tests, neither buffer-free nor conventionally buffered solution conditions showed significant pH changes. Conventionally buffered solutions showed significantly higher opalescence than buffer-free ones. In general, buffer-free solution conditions showed less aggregation than conventionally buffered solutions. Shaking stability tests showed no differences between buffer-free and conventionally buffered solutions. "In-use" preparation experiments showed that pH in infusion bag medium can rapidly approximate that of self-buffered protein concentrate as concentrate is added. In summary, the buffer capacity of proteins can be predicted and buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A comparative study of the processes of generation of singlet oxygen upon irradiation of aqueous preparations on the basis of chlorin e6 and coproporphyrin III

NASA Astrophysics Data System (ADS)

Bagrov, I. V.; Belousova, I. M.; Gorelov, S. I.; Dobrun, M. V.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, A. V.; Kris'ko, T. K.

2017-02-01

The photosensitizing ability of an agent based on chlorin e6 (Photoditazin), which is used for photodynamic diagnosis and therapy, is compared with that of a new preparation on the basis of coproporphyrin III in the environment of a phosphate buffer and a simulated biological environment (albumin solution). The efficiency of singlet-oxygen production was estimated by EPR spectroscopy and spectroscopy in the UV and visible ranges with the use of "chemical traps" of singlet oxygen. By irradiating drugs with LED emission centered at λmax = 520 nm, we determined the quantum yield of singlet-oxygen production in a buffer solution; the obtained values are 0.60 and 0.37 for chlorine and coproporphyrin, respectively. The steady-state concentration of singlet oxygen upon irradiation of solutions of the studied photosensitizers with concentrations of 12-43 μM and the density of radiation power within the 6-96 W/cm2 region was found to be in the region of 1010-1011 molecules/cm3. It is shown that the introduction into the solution of egg albumin (0.1%) reduces the sensitizing properties of the two drugs by two to three times, while the efficiencies of the preparations with respect to singlet-oxygen production become almost identical (0.19 and 0.17).

Square-wave adsorptive stripping voltammetric determination of nanomolar levels of bezafibrate using a glassy carbon electrode modified with multi-walled carbon nanotubes within a dihexadecyl hydrogen phosphate film.

PubMed

Ardila, Jorge Armando; Oliveira, Geiser Gabriel; Medeiros, Roberta Antigo; Fatibello-Filho, Orlando

2014-04-07

A highly sensitive method for bezafibrate determination using a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes within a dihexadecyl hydrogen phosphate film based on square-wave adsorptive stripping voltammetry (SWAdSV) is proposed. The electrochemical behaviour of bezafibrate has been studied by cyclic voltammetry, showing an irreversible anodic peak at a potential of 1.09 V in 0.1 mol L(-1) phosphate buffer solution (pH 2.0). A study of the scan rate showed that the oxidation of bezafibrate is an adsorptive-controlled process, involving the transfer of two electrons and two protons per molecule. The analytical curve was linear over a bezafibrate concentration range from 50 to 910 nmol L(-1), with a detection limit of 16 nmol L(-1). This analytical method was successfully applied for benzafibrate determination in pharmaceutical formulations, with results showing good agreement with those obtained using a comparative spectrophotometric method, and has the potential for field application.

Indigo Carmine-Cu complex probe exhibiting dual colorimetric/fluorimetric sensing for selective determination of mono hydrogen phosphate ion and its logic behavior

NASA Astrophysics Data System (ADS)

Tavallali, Hossein; Deilamy-Rad, Gohar; Moaddeli, Ali; Asghari, Khadijeh

2017-08-01

A new selective probe based on copper complex of Indigo Carmine (IC-Cu2) for colorimetric, naked-eye, and fluorimetric recognition of mono hydrogen phosphate (MHP) ion in H2O/DMSO (4:1 v/v, 1.0 mmol L- 1 HEPES buffer solution pH 7.5) was developed. Detection limit of HPO42 - determination, achieved by fluorimetric and 3lorimetric method, are 0.071 and 1.46 μmol L- 1, respectively. Potential, therefore is clearly available in IC-Cu2 complex to detect HPO42 - in micromolar range via dual visible color change and fluorescence response. Present method shows high selectivity toward HPO42 - over other phosphate species and other anions and was successfully utilized for analysis of P2O5 content of a fertilizer sample. The results obtained by proposed chemosensor presented good agreement with those obtained the colorimetric reference method. INHIBIT and IMPLICATION logic gates operating at molecular level have been achieved using Cu2 + and HPO42 - as chemical inputs and UV-Vis absorbance signal as output.

Characterization and in vitro biological evaluation of mineral/osteogenic growth peptide nanocomposites synthesized biomimetically on titanium

NASA Astrophysics Data System (ADS)

Chen, Cen; Kong, Xiangdong; Zhang, Sheng-Min; Lee, In-Seop

2015-04-01

Nanocomposite layers of mineral/osteogenic growth peptide (OGP) were synthesized on calcium phosphate coated titanium substrates by immersing in calcium-phosphate buffer solution containing OGP. Peptide incorporated mineral was characterized by determining quantity loaded, effects on mineral morphology and structure. Also, the biological activity was investigated by cell adhesion, proliferation assay, and measurement of alkaline phosphatase (ALP) activity. X-ray photoelectron spectroscopy (XPS) and micro-bicinchoninic acid (BCA) assay revealed that OGP was successfully incorporated with mineral and the amount was increased with immersion time. Incorporated OGP changed the mineral morphology from sharp plate-like shape to more rounded one, and the octacalcium phosphate structure of the mineral was gradually transformed into apatite. With confocal microscopy to examine the incorporation of fluorescently labeled peptide, OGP was evenly distributed throughout mineral layers. Mineral/OGP nanocomposites promoted cell adhesion and proliferation, and also increased ALP activity of mesenchymal stem cells (MSCs). Results presented here indicated that the mineral/OGP nanocomposites formed on titanium substrates had the potential for applications in dental implants.

Studies on aqueous two phase polymer systems useful for partitioning of biological materials

NASA Technical Reports Server (NTRS)

Brooks, D. E.; Bamberger, S.

1982-01-01

The two phase systems that result when aqueous solutions of dextran and poly(ethylene glycol) (PEG) are mixed above a critical concentration of a few percent provide a useful medium for the separation of biological cell subpopulations via partition between the top, PEG-rich phase and the liquid-liquid phase boundary. Interfacial tensions of such systems have been measured by the rotating drop technique and found to range between 0.1-100 micro-N/m. The tension was found to depend on the length of the tie line describing the system on a phase diagram, via a power law relationship which differed depending on the concentration of Na phosphate buffer present. The electrokinetic properties of drops of one phase suspended in the other were studied for a variety of systems. It was found that the droplet electrophoretic mobility increased monotonically with phosphate concentration and drop diameter but exhibited the opposite sign from that anticipated from phosphate partition measurements. It was possible to take advantage of these electrokinetic properties and dramatically enhance the speed of phase separation through application of relatively small electric fields.

Optical biosensor based on liquid crystal droplets for detection of cholic acid

NASA Astrophysics Data System (ADS)

Niu, Xiaofang; Luo, Dan; Chen, Rui; Wang, Fei; Sun, Xiaowei; Dai, Haitao

2016-12-01

A highly sensitive cholic acid biosensor based on 4-cyano-4‧-penthlbiphenyl (5CB) Liquid crystal droplets in phosphate buffer saline solution was reported. A radial-to-bipolar transition of 5CB droplet would be triggered during competitive reaction of CA at the sodium dodecyl sulfate surfactant-laden 5CB droplet surface. Our liquid crystal droplet sensor is a low-cost, simple and fast method for CA detection. The detection limit (5 μM) of our method is 2.4 times lower than previously report by using liquid crystal film to detection of CA.

High sensitivity and high Q-factor nanoslotted parallel quadrabeam photonic crystal cavity for real-time and label-free sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Daquan; State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876; School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138

We experimentally demonstrate a label-free sensor based on nanoslotted parallel quadrabeam photonic crystal cavity (NPQC). The NPQC possesses both high sensitivity and high Q-factor. We achieved sensitivity (S) of 451 nm/refractive index unit and Q-factor >7000 in water at telecom wavelength range, featuring a sensor figure of merit >2000, an order of magnitude improvement over the previous photonic crystal sensors. In addition, we measured the streptavidin-biotin binding affinity and detected 10 ag/mL concentrated streptavidin in the phosphate buffered saline solution.

Covalent conjugation of graphene oxide with methotrexate and its antitumor activity

NASA Astrophysics Data System (ADS)

Wojtoniszak, M.; Urbas, K.; Perużyńska, M.; Kurzawski, M.; Droździk, M.; Mijowska, E.

2013-05-01

Here, we have functionalized graphene oxide with anticancer drug methotrexate through amide bonding. A kinetics of the drug release from graphene oxide in physiological solution - phosphate buffered saline (PBS) containing different biocompatible polymers have been investigated. Dispersion of MTX-GO in poly sodium-4-styrene sulfonate and poly ethylene glycol resulted in increase of the release time. The material was characterized with transmission electron microscopy, atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and UV-vis spectroscopy. Furthermore, antineoplastic action against human breast adenocarcinoma cell line MCF7 of MTX-GO and empty graphene oxide was explored.

Influence of D-Penicillamine on the Viscosity of Hyaluronic Acid Solutions

NASA Astrophysics Data System (ADS)

Liang, Jing; Krause, Wendy E.; Colby, Ralph H.

2006-03-01

Polyelectrolyte hyaluronic acid (HA, hyaluronan) is an important component in synovial fluid. Its presence results in highly viscoelastic solutions with excellent lubricating and shock-absorbing properties. In comparison to healthy synovial fluid, diseased fluid has a reduced viscosity. In osteoarthritis this reduction in viscosity results from a decline in both the molecular weight and concentration of hyaluronic acid HA. Initial results indicate that D-penicillamine affects the rheology of bovine synovial fluid, a model synovial fluid solution, and its components, including HA. In order to understand how D-penicillamine modifies the viscosity of these solutions, the rheological properties of sodium hyaluronate (NaHA) in phosphate-buffered saline (PBS) with D-penicillamine were studied as function of time, D-penicillamine concentration (0 -- 0.01 M), and storage conditions. Penicillamine has a complex, time dependent effect on the viscosity of NaHA solutions---reducing the zero shear rate viscosity of a 3 mg/mL NaHA in PBS by ca. 40% after 44 days.

Assessment of the ``cross-bridge''-induced interaction of red blood cells by optical trapping combined with microfluidics

NASA Astrophysics Data System (ADS)

Lee, Kisung; Wagner, Christian; Priezzhev, Alexander V.

2017-09-01

Red blood cell (RBC) aggregation is an intrinsic property of the blood that has a direct effect on the blood viscosity and circulation. Nevertheless, the mechanism behind the RBC aggregation has not been confirmed and is still under investigation with two major hypotheses, known as "depletion layer" and "cross-bridging." We aim to ultimately understand the mechanism of the RBC aggregation and clarify both models. To measure the cell interaction in vitro in different suspensions (including plasma, isotonic solution of fibrinogen, isotonic solution of fibrinogen with albumin, and phosphate buffer saline) while moving the aggregate from one solution to another, an approach combining optical trapping and microfluidics has been applied. The study reveals evidence that RBC aggregation in plasma is at least partly due to the cross-bridging mechanism. The cell interaction strength measured in the final solution was found to be significantly changed depending on the initial solution where the aggregate was formed.

Mechanisms of Arsenic Hyperaccumulation in Pteris vittata. Uptake Kinetics, Interactions with Phosphate, and Arsenic Speciation1

PubMed Central

Wang, Junru; Zhao, Fang-Jie; Meharg, Andrew A.; Raab, Andrea; Feldmann, Joerg; McGrath, Steve P.

2002-01-01

The mechanisms of arsenic (As) hyperaccumulation in Pteris vittata, the first identified As hyperaccumulator, are unknown. We investigated the interactions of arsenate and phosphate on the uptake and distribution of As and phosphorus (P), and As speciation in P. vittata. In an 18-d hydroponic experiment with varying concentrations of arsenate and phosphate, P. vittata accumulated As in the fronds up to 27,000 mg As kg−1 dry weight, and the frond As to root As concentration ratio varied between 1.3 and 6.7. Increasing phosphate supply decreased As uptake markedly, with the effect being greater on root As concentration than on shoot As concentration. Increasing arsenate supply decreased the P concentration in the roots, but not in the fronds. Presence of phosphate in the uptake solution decreased arsenate influx markedly, whereas P starvation for 8 d increased the maximum net influx by 2.5-fold. The rate of arsenite uptake was 10% of that for arsenate in the absence of phosphate. Neither P starvation nor the presence of phosphate affected arsenite uptake. Within 8 h, 50% to 78% of the As taken up was distributed to the fronds, with a higher translocation efficiency for arsenite than for arsenate. In fronds, 49% to 94% of the As was extracted with a phosphate buffer (pH 5.6). Speciation analysis using high-performance liquid chromatography-inductively coupled plasma mass spectroscopy showed that >85% of the extracted As was in the form of arsenite, and the remaining mostly as arsenate. We conclude that arsenate is taken up by P. vittata via the phosphate transporters, reduced to arsenite, and sequestered in the fronds primarily as As(III). PMID:12428020

Polydopamine-induced tooth remineralization.

PubMed

Zhou, Yun-Zhi; Cao, Ying; Liu, Wei; Chu, Chun Hung; Li, Quan-Li

2012-12-01

Inspired by mussel bioadhesion in nature, dopamine is extensively used for biomaterial surface modification. In this study, we coated dopamine on demineralized enamel and dentin surfaces to evaluate the effect of polydopamine coating on dental remineralization. Dental slices containing enamel and dentin were first etched with 37% phosphoric acid for 2 min, followed by immersion in a 2 mg/mL freshly prepared solution of dopamine (10 mM Tris buffer, pH 8.5) for approximately 24 h at room temperature in the dark to obtain polydopamine coating. Then, the dental slices with and without polydopamine coating were immersed in the supersaturated solution of calcium and phosphate at 37 °C for 2 and 7 days. The supersaturated solution of calcium and phosphate was refreshed each day. The precipitates were characterized by SEM, XRD, FTIR, microhardness, and nanoscratch analyses. No significant difference was observed in the remineralization of enamel whether it was coated with polydopamine or not. However, a significant difference was found in dentin remineralization between dentin with and without polydopamine coating. Polydopamine coating remarkably promoted demineralized dentin remineralization, and all dentin tubules were occluded by densely packed hydroxyapatite crystals. Thus, coating polydopamine on dental tissue surface may be a simple universal technique to induce enamel and dentin remineralization simultaneously.

[Simultaneous determination of scopolamine hydrobromide, atropine sulfate, ephedrine hydrochloride and pseudoephedrine hydrochloride in Zhichuanling oral liquid with HPLC].

PubMed

Zhang, Yu-Lin; Li, Yu-Ping

2013-10-01

To establish an HPLC method for determining the contents of scopolamine hydrobromide, atropine sulfate, ephedrine hydrochloride and pseudoephedrine hydrochloride in Zhichuanling oral liquid. Agela Durashell RP-C18 (4. 6 mm x250 mm, 5 microm) was adopted, with acetonitrile-sodium phosphate buffer solution (0. 07 mol L-1 sodium phosphate solution with 17.5 mmol L-1 sodium dodecylsulfate adjusted to pH 6.0 with phosphoric acid solution) (30:70) as the mobile phase. The flow rate was 0. 9 mL min -1, the detection wavelength was 207 nm, and the column temperature was 25 degree C. Scopolamine hydrobromide, atropine sulfate, ephedrine hlvdrochloride and pseudoephedrine hydrochloride showed good linear relations with peak areas within the concentration range of 0. 021 21-1. 060 5 pg (r =0. 999 3) , 0. 011 14-0. 557 microg (r = 0. 999 6) , 0. 200 56-10. 028 microg (r =0. 999 7) and 0.070 33-3. 516 5 gg (r =0. 999 6), respectively, with the average recoveries of 101.9% , 99. 80%, 100. 3%, 100. 2% (n=6). The method was so quick, simple, highly reproducible and specific that it could be used as one of quality control methods of Zhichuanling oral liquid.

Solution dynamics of synthetic and natural polyelectrolytes

NASA Astrophysics Data System (ADS)

Krause, Wendy E.

Polyelectrolytes are abundant in nature and essential to life, and used extensively in industry. This work discussed two polyelectrolytes: sodium poly(2-acrylamido-2-methylpropanesulfonate) (NaPAMS), synthetic polyelectrolyte, and sodium hyaluronate (NaHA), a glycosaminoglycan. Rheological data of NaPAMS solutions of variable chain length and concentration were reported. A strong dependence of viscosity eta on chain length: eta ˜ M2.4 was found. The comparison of the rheological data with two proposed scaling theories (Dobrynin 1995, Witten 1987) forces the conclusion that neither theory is correct. A possible interpretation of the viscosity data falling between the predictions of the two scaling theories is that some chain rigidity may persist beyond the correlation length. A sample model for the conductivity of semidilute polyelectrolytes with no added salt was presented. The model correctly describes the logarithmic decrease of specific conductance observed for many polyelectrolytes at low concentration (below ca. 10-2M), and is in good agreement with data from NaPAMS solutions. NaHA in phosphate buffered saline behaves as a typical polyelectrolyte in the high-salt limit, as Newtonian viscosities are observed over a wide range of shear rates. There is no evidence of intermolecular hydrogen bonding causing gel formation in NaHA solutions without protein present. The viscosity of 3 mg/mL NaHA was measured in the presence of the selected anti-inflammatory agents. Of the seven additives investigated only (D)-penicillamine significantly altered the rheology of HA. (D)-Penicillamine dramatically reduced the viscosity of HA, probably by disrupting intramolecular hydrogen bonding. The plasma proteins albumin and gamma-globulins bind to HA in solution to form a weak reversible gel. The rheology and osmotic pressure of the simple model for synovial fluid, consisting of 3mg/mL NaHA, 11 mg/mL albumin, and 7 mg/mL gamma-globulins in phosphate buffered saline, were studied in the presence and absence of the seven selected anti-inflammatory agents. Only hydroxychloroquine (HCQ) and (D)-penicillamine strongly influence the theology of the synovial fluid model. HCQ reduces the viscosity of the model solution as well as the model's viscoelasticity. (D)-Penicillamine also reduces the viscosity of the synovial fluid model, but has little effect on the viscoelasticity of the solution. None of the additives effected the osmotic pressure of the synovial fluid model.

Partition coefficients of some purine derivatives and its application to pharmacokinetics.

PubMed

Chrzanowska, M; Sobiak, J; Kuehn, M; Dorawa, E; Hermann, T

2009-12-01

Metazathioprine (MAZA), a methylated derivative of azathioprine (AZA), demonstrated the greatest values of apparent and specific partition coefficients in n-octanol/phosphate buffer at pH 5.7 and pH 7.4 among purine derivatives such as 6-mercaptopurine (6-MP), 6-thioguanine (6-TG) and AZA. Introduction of a methyl group into the imidazole ring of AZA increases lipophilic properties of MAZA compared to AZA. Mass balance of purine derivatives in n-octanol and in phosphate buffer indicated their chemical stability in those media.

Release of Ciprofloxacin-HCl and Dexamethasone Phosphate by Hyaluronic Acid Containing Silicone Polymers.

PubMed

Nguyen, Darrene; Hui, Alex; Weeks, Andrea; Heynen, Miriam; Joyce, Elizabeth; Sheardown, Heather; Jones, Lyndon

2012-04-19

The purpose of this study was to determine the effect of the covalent incorporation of hyaluronic acid (HA) into conventional hydrogel and hydrogels containing silicone as models for contact lens materials on the uptake and release of the fluoroquinolone antibiotic ciprofloxacin and the anti-inflammatory steroid dexamethasone phosphate. A 3 mg/mL ciprofloxacin solution (0.3% w/v) and a 1 mg/mL dexamethasone phosphate solution (0.1%) was prepared in borate buffered saline. Three hydrogel material samples (pHEMA; pHEMA TRIS; DMAA TRIS) were prepared with and without the covalent incorporation of HA of molecular weight (MW) 35 or 132 kDa. Hydrogel discs were punched from a sheet of material with a uniform diameter of 5 mm. Uptake kinetics were evaluated at room temperature by soaking the discs for 24 h. Release kinetics were evaluated by placing the drug-loaded discs in saline at 34 °C in a shaking water bath. At various time points over 6-7 days, aliquots of the release medium were assayed for drug amounts. The majority of the materials tested released sufficient drug to be clinically relevant in an ophthalmic application, reaching desired concentrations for antibiotic or anti-inflammatory activity in solution. Overall, the silicone-based hydrogels (pHEMA TRIS and DMAA TRIS), released lower amounts of drug than the conventional pHEMA material (p < 0.001). Materials with HA MW132 released more ciprofloxacin compared to materials with HA MW35 and lenses without HA (p < 0.02). Some HA-based materials were still releasing the drug after 6 days.

An Efficient Method for Co-purification of Eggshell Matrix Proteins OC-17, OC-116, and OCX-36

PubMed Central

2016-01-01

In this study, we improved the eggshell-membrane separation process by separating the shell and membrane with EDTA solution, evaluating effects of three different extraction solutions (acetic acid, EDTA, and phosphate solution), and co-purifying multiple eggshell proteins with two successive ion-exchange chromatography procedures (CM Sepharose Fast Flow and DEAE Sepharose Fast Flow). The recovery and residual rates of eggshell and membrane separated by the modified method with added EDTA solution were 93.88%, 91.15% and 1.01%, 2.87%, respectively. Ovocleidin-116 (OC-116) and ovocalyxin-36 (OCX-36) were obtained by loading 50 mM Na-Hepes, pH 7.5, 2 mM DTT and 350 mM NaCl buffer onto the DEAE-FF column at a flow rate of 1 mL/min, ovocleidin-17 (OC-17) was obtained by loading 100 mM NaCl, 50 mM Tris, pH 8.0 on the CM-FF column at a flow rate of 0.5 mL/min. The purities of OCX-36, OC-17 and OC-116 were 96.82%, 80.15% and 73.22%, and the recovery rates were 55.27%, 53.38% and 36.34%, respectively. Antibacterial activity test suggested that phosphate solution extract exhibited significantly higher activity against the tested bacterial strains than the acetic acid or EDTA extract, probably due to more types of proteins in the extract. These results demonstrate that this separation method is feasible and efficient. PMID:28115888

[Isolation and purification of recombinant soluble and non-fusion angiogenesis inhibitor Kringle 5 using chromatography].

PubMed

Ma, Lina; Wu, Dan; Bian, Liujiao

2012-08-01

The Kringle 5 domain of plasminogen is one of the most potent angiogenesis inhibitors known to date, which can inhibit cell proliferation and migration efficiently. In the study, on the foundation of successful clone and expression of recombinant soluble and non-fusion angiogenesis inhibitor Kringle 5, a two-step chromatographic method, including the use of SP Sepharose Fast Flow cation exchanger and Sephacryl S-100 HR size exclusion chromatography in sequence, was established to separate and purify angiogenesis inhibitor Kringle 5. On the SP Sepharose Fast Flow column, the buffer A consisted of 50.0 mmol/L acetic acid-sodium acetate (pH 5.2), and the buffer B consisted of buffer A with the addition of 0.5 mol/L sodium chloride (pH 5.2); on Sephacryl S-100 HR column, the elution buffer was 5.0 mmol/L phosphate solution (pH 7.0). Through the two-step chromatographic purification process, the purity of the obtained Kringle 5 was more than 98%. In addition, it was found that the obtained Kringle 5 could inhibit the blood vessel growth of chick embryo chorioallantoic membrane effectively. Finally it is concluded that this method can effectively separate active recombinant soluble and non-fusion angiogenesis inhibitor Kringle 5.

Chelatable trace zinc causes low, irreproducible KDAC8 activity.

PubMed

Toro, Tasha B; Edenfield, Samantha A; Hylton, Brandon J; Watt, Terry J

2018-01-01

Acetylation is an important regulatory mechanism in cells, and emphasis is being placed on identifying substrates and small molecule modulators of this post-translational modification. However, the reported in vitro activity of the lysine deacetylase KDAC8 is inconsistent across experimental setups, even with the same substrate, complicating progress in the field. We detected trace levels of zinc, a known inhibitor of KDAC8 when present in excess, even in high-quality buffer reagents, at concentrations that are sufficient to significantly inhibit the enzyme under common reaction conditions. We hypothesized that trace zinc in solution could account for the observed variability in KDAC8 activity. We demonstrate that addition of chelators, including BSA, EDTA, and citrate, and/or the use of a phosphate-based buffer instead of the more common tris-based buffer, eliminates the inhibition from low levels of zinc as well as the dependence of specific activity on enzyme concentration. This results in high KDAC8 activity that is consistent across buffer systems, even using low concentrations of enzyme. We report conditions that are suitable for several assays to increase both enzyme activity and reproducibility. Our results have significant implications for approaches used to identify substrates and small molecule modulators of KDAC8 and interpretation of existing data. Copyright © 2017 Elsevier Inc. All rights reserved.

Coassembly of Lysozyme and Amphiphilic Biomolecules Driven by Unimer-Aggregate Equilibrium.

PubMed

Tao, Yuanyuan; Ma, Xiaoteng; Cai, Yaqian; Liu, Li; Zhao, Hanying

2018-04-12

Synthesis and self-assembly of bioconjugates composed of proteins and synthetic molecules have been widely studied because of the potential applications in medicine, biotechnology, and nanotechnology. One of the challenging research studies in this area is to develop organic solvent-free approaches to the synthesis and self-assembly of amphiphilic bioconjugates. In this research, dialysis-assisted approach, a method based on unimer-aggregate equilibrium, was applied in the coassembly of lysozyme and conjugate of cholesterol and glutathione (Ch-GSH). In phosphate buffer solution, amphiphilic Ch-GSH conjugate self-assembles into vesicles, and the vesicle solution is dialyzed against lysozyme solution. Negatively charged Ch-GSH unimers produced in the unimer-vesicle exchange equilibrium, diffuse across the dialysis membrane and have electrostatic interaction with positively charged lysozyme, resulting in the formation of Ch-GSH-lysozyme bioconjugate. Above a critical concentration, the three-component bioconjugate molecules self-assemble into bioactive vesicles.

Metal sulfide and rare-earth phosphate nanostructures and methods of making same

DOEpatents

Wong, Stanislaus; Zhang, Fen

2016-06-28

The present invention provides a method of producing a crystalline rare earth phosphate nanostructure. The method comprising: providing a rare earth metal precursor solution and providing a phosphate precursor solution; placing a porous membrane between the metal precursor solution and the phosphate precursor solution, wherein metal cations of the metal precursor solution and phosphate ions of the phosphate precursor solution react, thereby producing a crystalline rare earth metal phosphate nanostructure.

Small unilamellar liposomes as a membrane model for cell inactivation by cold atmospheric plasma treatment

NASA Astrophysics Data System (ADS)

Maheux, S.; Frache, G.; Thomann, J. S.; Clément, F.; Penny, C.; Belmonte, T.; Duday, D.

2016-09-01

Cold atmospheric plasma is thought to be a promising tool for numerous biomedical applications due to its ability to generate a large diversity of reactive species in a controlled way. In some cases, it can also generate pulsed electric fields at the zone of treatment, which can induce processes such as electroporation in cell membranes. However, the interaction of these reactive species and the pulse electric field with cells in a physiological medium is very complex, and we still need a better understanding in order to be useful for future applications. A way to reach this goal is to work with model cell membranes such as liposomes, with the simplest physiological liquid and in a controlled atmosphere in order to limit the number of parallel reactions and processes. In this paper, where this approach has been chosen, 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) small unilamellar vesicles (SUV) have been synthesized in a phosphate buffered aqueous solution, and this solution has been treated by a nanosecond pulsed plasma jet under a pure nitrogen atmosphere. It is only the composition of the plasma gas that has been changed in order to generate different cocktails of reactive species. After the quantification of the main plasma reactive species in the phosphate buffered saline (PBS) solution, structural, surface charge state, and chemical modifications generated on the plasma treated liposomes, due to the interaction with the plasma reactive species, have been carefully characterized. These results allow us to further understand the effect of plasma reactive species on model cell membranes in physiological liquids. The permeation through the liposomal membrane and the reaction of plasma reactive species with molecules encapsulated inside the liposomes have also been evaluated. New processes of degradation are finally presented and discussed, which come from the specific conditions of plasma treatment under the pure nitrogen atmosphere.

Triple Antibiotic Polymer Nanofibers for Intracanal Drug Delivery: Effects on Dual Species Biofilm and Cell Function.

PubMed

Pankajakshan, Divya; Albuquerque, Maria T P; Evans, Joshua D; Kamocka, Malgorzata M; Gregory, Richard L; Bottino, Marco C

2016-10-01

Root canal disinfection and the establishment of an intracanal microenvironment conducive to the proliferation/differentiation of stem cells play a significant role in regenerative endodontics. This study was designed to (1) investigate the antimicrobial efficacy of triple antibiotic-containing nanofibers against a dual-species biofilm and (2) evaluate the ability of dental pulp stem cells (DPSCs) to adhere to and proliferate on dentin upon nanofiber exposure. Seven-day-old dual-species biofilm established on dentin specimens was exposed for 3 days to the following: saline (control), antibiotic-free nanofibers (control), and triple antibiotic-containing nanofibers or a saturated triple antibiotic paste (TAP) solution (50 mg/mL in phosphate buffer solution). Bacterial viability was assessed using the LIVE/DEAD assay (Molecular Probes, Inc, Eugene, OR) and confocal laser scanning microscopy. For cytocompatibility studies, dentin specimens after nanofiber or TAP (1 g/mL in phosphate buffer solution) exposure were evaluated for cell adhesion and spreading by actin-phalloidin staining. DPSC proliferation was assessed on days 1, 3, and 7. Statistics were performed, and significance was set at the 5% level. Confocal laser scanning microscopy showed significant bacterial death upon antibiotic-containing nanofiber exposure, differing significantly (P < .05) from antibiotic-free fibers and the control (saline). DPSCs showed enhanced adhesion/spreading on dentin specimens treated with antibiotic-containing nanofibers when compared with its TAP counterparts. The DPSC proliferation rate was similar on days 1 and 3 in antibiotic-free nanofibers, triple antibiotic-containing nanofibers, and TAP-treated dentin. Proliferation was higher (9-fold) on dentin treated with antibiotic-containing nanofibers on day 7 compared with TAP. Triple antibiotic-containing polymer nanofibers led to significant bacterial death, whereas they did not affect DPSC attachment and proliferation on dentin. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

In Vitro Anti-inflammatory and Antimicrobial Activities of Azithromycin After Loaded in Chitosan- and Tween 20-Based Oil-in-Water Macroemulsion for Acne Management.

PubMed

Shunmugaperumal, Tamilvanan; Kaur, Varinder

2016-06-01

The objectives of the current investigation are (1) to prepare and characterize (particle size, surface charge (potential zeta), surface morphology by transmission electron microscopy, drug content, and drug release) the azithromycin (AZM, 100 mg)-loaded oil-in-water (o/w) macroemulsion, (2) to assess the toxicity of macroemulsion with or without AZM using RBC lysis test in comparison with AZM in phosphate buffer solution of pH 7.4, (3) to compare the in vitro antimicrobial activity (in Escherichia coli using zone inhibition assay) of AZM-loaded macroemulsion with its aqueous solution, and (4) to assess the in vitro anti-inflammatory effect (using egg albumin denaturation bioassay) of the AZM-loaded macroemulsion in comparison with diclofenac sodium in phosphate buffer solution of pH 7.4. The AZM-loaded macroemulsion possessed the dispersed oil droplets with a mean diameter value of 52.40 ± 1.55 μm. A reversal in the zeta potential value from negative (-2.16 ± 0.75 mV) to positive (+6.52 ± 0.96 mV) was noticed when AZM was added into the macroemulsion. At a 1:5 dilution ratio, 2.06 ± 0.03 mg of drug was released from macroemulsion followed by 1.01 ± 0.01 and 0.25 ± 0.08 mg, respectively, for 1:10 and 1:40 dilution ratios. Antimicrobial activity maintenance and significant reduction of RBC lysis property were noticed for AZM after loaded in the macroemulsion. However, an increment in the absorbance values for emulsion-treated samples in comparison to the control samples was noticed in the anti-inflammatory test. This speculates the potential of the AZM-loaded emulsion to manage inflammatory conditions produced at Acne vulgaris.

Effects of porosity on corrosion resistance of Mg alloy foam produced by powder metallurgy technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aghion, E., E-mail: egyon@bgu.ac.il; Perez, Y.

2014-10-15

Magnesium alloy foams have the potential to serve as structural material for regular light-weight applications as well as for biodegradable scaffold implants. However, their main disadvantage relates to the high reactivity of magnesium and consequently their natural tendency to corrode in regular service conditions and in physiological environments. The present study aims at evaluating the effect of porosity on the corrosion resistance of MRI 201S magnesium alloy foams in 0.9% NaCl solution and in phosphate buffer saline solution as a simulated physiological electrolyte. The magnesium foams were produced by powder metallurgy technology using space-holding particles to control the porosity content.more » Machined chips were used as raw material for the production of Mg alloy powder by milling process. The microstructure of the foams was examined using optical and scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. The corrosion behavior was evaluated by immersion test and potentiodynamic polarization analysis. The results obtained clearly demonstrate that the porosity has a significant effect on the corrosion resistance of the tested foams. Foams with 14–19% porosity have a corrosion rate of 4–10 mcd and 7–15 mcd in NaCl and phosphate buffer saline solution, respectively, compared to only 0.10 mcd for the same alloy in as cast conditions. This increased corrosion degradation of the Mg foams by more than one order of magnitude compared to the cast alloy may limit their potential application in regular and physiological environments. - Highlights: • Porosity has a detrimental effect on corrosion resistance of MRI 201S Mg foams. • 14–19% porosity increases the corrosion rate by more than one order of magnitude. • Accelerated corrosion limits the use of foams in regular/physiological environments.« less

Effect of dissolution of magnesium alloy AZ31 on the rheological properties of Phosphate Buffer Saline.

PubMed

Riaz, Usman; Rakesh, Leela; Shabib, Ishraq; Haider, Waseem

2018-06-05

The issue of long-term incompatible interactions associated with the permanent implants can be eliminated by using various biodegradable metal implants. The recent research is focusing on the use of degradable stents to restore most of the hindrances of capillaries, and coronary arteries by supplying instant blood flow with constant mechanical and structural support. However, internal endothelialization and infection due to the corrosion of implanted stents are not easy to diagnose in the long run. In the recent past, magnesium (Mg) has been widely investigated for the cardiovascular stent applications. Here we made an attempt to understand the biodegradation process of Mg alloy stent by studying the degradation of Mg alloy AZ31 (3 wt% Aluminum, 1 wt% Zn) powder at various time-intervals in simulated blood fluid using the Rheological methods. The degradability of the Mg stent in the arteries affects the stress-strain properties of blood plasma and the subsequent flow conditions. Blood and plasma viscosities alter due to the degradation of Mg resulting from the stress-strain experienced in the blood vessels, in which the stent is inserted. Here our objective was to explore the influence of Mg degradation on the blood plasma viscosity by studying the viscoelastic properties. In this work, the effect of dissolution of Mg alloy AZ31 on the rheological properties of Phosphate Buffer Saline (PBS) at various time intervals have been investigated. The viscosity of the PBS-AZ31 solution increased with the dissolution of both slurries and percolated clear solution. The only exception was day-7 of the percolated clear solution, where viscosity was decreased showing a reduction in viscosity at initial stages of dissolution. The frequency sweep showed the tendency of the PBS-AZ31 gelation up to 100 rad/s frequency. Copyright © 2018 Elsevier Ltd. All rights reserved.

Remote loading of doxorubicin into liposomes driven by a transmembrane phosphate gradient.

PubMed

Fritze, Andreas; Hens, Felicitas; Kimpfler, Andrea; Schubert, Rolf; Peschka-Süss, Regine

2006-10-01

This study examines a new method for the remote loading of doxorubicin into liposomes. It was shown that doxorubicin can be loaded to a level of up to 98% into large unilamellar vesicles composed of egg phosphatidylcholine/cholesterol (7/3 mol/mol) with a transmembrane phosphate gradient. The different encapsulation efficiencies which were achieved with ammonium salts (citrate 100%, phosphate 98%, sulfate 95%, acetate 77%) were significantly higher as compared to the loading via sodium salts (citrate 54%, phosphate 52%, sulfate 44%, acetate 16%). Various factors, including pH-value, buffer capacity, solubility of doxorubicin in different salt solutions and base counter-flow, which likely has an influence on drug accumulation in the intraliposomal interior are taken into account. In contrast to other methods, the newly developed remote loading method exhibits a pH-dependent drug release property which may be effective in tumor tissues. At physiological pH-value doxorubicin is retained in the liposomes, whereas drug release is achieved by lowering the pH to 5.5 (approximately 25% release at 25 degrees C or 30% at 37 degrees C within two h). The DXR release of liposomes which were loaded via a sulfate gradient showed a maximum of 3% at pH 5.5.

Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

NASA Astrophysics Data System (ADS)

Chopra, Shruti; Motwani, Sanjay K.; Ahmad, Farhan J.; Khar, Roop K.

2007-11-01

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20 μg mL -1 ( r2 = 0.9999) in deionised water and 1-24 μg mL -1 ( r2 = 0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 × 10 3 L mol -1 cm -1 and 0.0422 μg cm -2/0.001A in deionised water; and 3.05 × 10 3 L mol -1 cm -1 and 0.0567 μg cm -2/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 μg mL -1 in deionised water and 0.13 and 0.40 μg mL -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

Simple electro-assisted immobilization of ciprofloxacin on carbon nanotube modified electrodes: its selective hydrogen peroxide electrocatalysis.

PubMed

Sornambikai, Sundaram; Kumar, Annamalai Senthil

2014-09-01

Ciprofloxacin (Cf) is a synthetic fourth generation fluoroquinolone class antibiotic used for the treatment of gram-positive, gram-negative and mycobacterium species infections. Electrochemical characteristic of the Cf antibiotic on carbon nanotube modified glassy carbon electrode (GCE/CNT) in pH 7 phosphate buffer solution has been investigated. Electrochemically oxidized radical byproduct of the Cf drug, which is formed as intermediate, gets immobilized on the GCE/CNT (GCE/Cf@CNT) and showed stable and well defined surface confined redox peak at -0.220 V versus Ag/AgCl. Control electrochemical experiment with unmodified GCE failed to show any such immobilization and redox features. Physicochemical characterizations of the Cf@CNT by transmission electron microscope, scanning electron microscope, infrared spectroscopy, UV-Vis and gas chromatography coupled mass spectroscopic analyses of Cf@CNT collectively revealed presence of native form of the Cf antibiotic molecule onto the CNT. The interaction between the Cf molecule and the CNT tubes are revealed from the decreased intensity in the Raman spectrum. The GCE/Cf@CNT showed excellent electrocatalytic response to hydrogen peroxide reduction reaction in pH 7 phosphate buffer solution. Amperometric i-t analysis for the detection of H2O2 showed a current linearity plot upto [H2O2] = 200 μM at an applied potential - 0.1 V versus Ag/AgCl with a current sensitivity value 678 μA mM(-1) cm(-2). No interferences were noticed with ascorbic acid, uric acid, cysteine and nitrite. The present study can be highly helpful to understand the interaction between the Cf and H2O2 in physiological systems and for the removal of Cf from the antibiotic polluted water samples especially in the aquaculture and agricultural systems.

Preparation of immunoglobulin Y from egg yolk using ammonium sulfate precipitation and ion exchange chromatography.

PubMed

Ko, K Y; Ahn, D U

2007-02-01

The objective of this study was to develop an economical, simple, and large-scale separation method for IgY from egg yolk. Egg yolk diluted with 9 volumes of cold water was centrifuged after adjusting the pH to 5.0. The supernatant was added with 0.01% charcoal or 0.01% carrageenan and centrifuged at 2,800 x g for 30 min. The supernatant was filtered through a Whatman no. 1 filter paper and then the filtrate was concentrated to 20% original volume using ultrafiltration. The concentrated solution was further purified using either cation exchange chromatography or ammonium sulfate precipitation. For the cation exchange chromatography method, the concentrated sample was loaded onto a column equilibrated with 20 mM citrate-phosphate buffer at pH 4.8 and eluted with 200 mM citrate-phosphate buffer at pH 6.4. For the ammonium sulfate precipitation method, the concentrated sample was twice precipitated with 40% ammonium sulfate solution at pH 9.0. The yield and purity of IgY were determined by ELISA and electrophoresis. The yield of IgY from the cation exchange chromatography method was 30 to 40%, whereas that of the ammonium sulfate precipitation was 70 to 80%. The purity of IgY from the ammonium sulfate method was higher than that of the cation exchange chromatography. The cation exchange chromatography could handle only a small amount of samples, whereas the ammonium sulfate precipitation could handle a large volume of samples. This suggests that ammonium sulfate precipitation was a more efficient and useful purification method than cation exchange chromatography for the large-scale preparation of IgY from egg yolk.

Effect of platelet activating factor with and without receptor antagonist (WEB2170) on morphology of isolated cochlear outer hair cells.

PubMed

Jung, Timothy T K; John, Earnest O; Park, Seong Kook; Park, Yong Soo; Rhee, Chong-Ku

2004-02-01

Platelet activating factor (PAF), generated from biologically active phospholipids, has been implicated as a potent inflammatory mediator and has been shown to be involved in many pathological processes, especially in inflammation and allergy. It has been suspected that PAF may be one of the inflammatory mediators in middle ear effusion that can induce sensorineural hearing loss, as observed in chronic otitis media. The PAF receptor antagonist WEB2170 has been studied extensively, and its inhibitory effects against various PAF actions are well proven in otologic systems. The purpose of our study was to determine the effect of superfusion of PAF and WEB2170 on morphological changes in isolated cochlear outer hair cells (OHCs). Isolated OHCs from adult chinchilla cochleas were exposed to albumin-phosphate-buffered saline solution (1 mg/mL), WEB2170 (5 mg/30 mL), PAF (1 micromol/L), or both PAF (I micromol/L) and WEB2170 (5 mg/30 mL). All experiments were performed at an osmolality of 305 +/- 5 mOsm at room temperature for 30 minutes. The cells were observed with an inverted microscope; the images were stored and analyzed on the Image Pro-Plus program. The OHCs exposed to control albumin-phosphate-buffered saline solution or to WEB2170 did not show any significant change in cell shape or length. The cells exposed to 1 micromol/L of PAF showed ballooning and significant shortening of the mean cell length in 15 to 20 minutes. These morphological changes in OHCs can be prevented by pretreating OHCs with WEB2170. This study demonstrated that exposure to PAF causes morphological changes in isolated OHCs that can be prevented by the PAF receptor antagonist WEB2170.

Synthesis of zinc-crosslinked thiolated alginic acid beads and their in vitro evaluation as potential enteric delivery system with folic acid as model drug.

PubMed

Taha, M O; Aiedeh, K M; Al-Hiari, Y; Al-Khatib, H

2005-10-01

The aim of this study is to explore the potential of synthetic modifications of alginic acid as a method to enhance the stability of its complexes with divalent cations under physiological conditions. A fraction of algin's carboxylic acid moieties was substituted with thiol groups to different substitution degrees through conjugating alginate to cysteine to produce alginate-cysteine (AC) conjugates. Infrared spectrophotometry and iodometry were used to characterize the resulting polymeric conjugates in terms of structure and degree of substitution. Moreover, zinc ions were used to crosslink the resulting AC polymers. Folic acid loaded beads were prepared from Zinc-crosslinked AC polymers (AC-Zn) of different cysteine substitution degrees. The generated beads were then investigated in vitro for their capacity to modify folic acid release. AC-Zn polymeric beads resisted drug release under acidic conditions (pH 1.0). However, upon transfer to a phosphate buffer solution (pH 7.0) they released most of their contents almost immediately. This change in drug release behavior is most probably due to the sequestering of zinc cations by phosphate ions within the buffer solution to form insoluble chelates and, to a lesser extent, the ionization of the carboxylic acid and thiol moieties. Removal of zinc ions from the polymeric matrix seems to promote polymeric disintegration and subsequent drug release. A similar behavior is expected in vivo due to the presence of natural zinc sequestering agents in the intestinal fluids. AC-Zn polymers provided a novel approach for enteric drug delivery as drug release from these matrices complied with the USP specifications for enteric dosage forms.

Fully Enzymatic Membraneless Glucose|Oxygen Fuel Cell That Provides 0.275 mA cm(-2) in 5 mM Glucose, Operates in Human Physiological Solutions, and Powers Transmission of Sensing Data.

PubMed

Ó Conghaile, Peter; Falk, Magnus; MacAodha, Domhnall; Yakovleva, Maria E; Gonaus, Christoph; Peterbauer, Clemens K; Gorton, Lo; Shleev, Sergey; Leech, Dónal

2016-02-16

Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) or [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.4, with 150 mM NaCl), higher glucose oxidation current densities, 0.41 mA cm(-2), are obtained from enzyme electrodes containing the deglycosylated form of the enzyme. The optimized glucose-oxidizing anode, prepared using deglycosylated enzyme coimmobilized with [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) and carbon nanotubes, was coupled with an oxygen-reducing bilirubin oxidase on gold nanoparticle dispersed on gold electrode as a biocathode to provide a membraneless fully enzymatic fuel cell. A maximum power density of 275 μW cm(-2) is obtained in 5 mM glucose in PBS, the highest to date under these conditions, providing sufficient power to enable wireless transmission of a signal to a data logger. When tested in whole human blood and unstimulated human saliva maximum power densities of 73 and 6 μW cm(-2) are obtained for the same fuel cell configuration, respectively.

Impact of Extraction Parameters on the Recovery of Lipolytic Activity from Fermented Babassu Cake

PubMed Central

Silva, Jaqueline N.; Godoy, Mateus G.; Gutarra, Melissa L. E.; Freire, Denise M. G.

2014-01-01

Enzyme extraction from solid matrix is as important step in solid-state fermentation to obtain soluble enzymes for further immobilization and application in biocatalysis. A method for the recovery of a pool of lipases from Penicillium simplicissimum produced by solid-state fermentation was developed. For lipase recovery different extraction solution was used and phosphate buffer containing Tween 80 and NaCl showed the best results, yielding lipase activity of 85.7 U/g and 65.7 U/g, respectively. The parameters with great impacts on enzyme extraction detected by the Plackett-Burman analysis were studied by Central Composite Rotatable experimental designs where a quadratic model was built showing maximum predicted lipase activity (160 U/g) at 25°C, Tween 80 0.5% (w/v), pH 8.0 and extraction solution 7 mL/g, maintaining constant buffer molarity of 0.1 M and 200 rpm. After the optimization process a 2.5 fold increase in lipase activity in the crude extract was obtained, comparing the intial value (64 U/g) with the experimental design (160 U/g), thus improving the overall productivity of the process. PMID:25090644

In-vitro and in-vivo study of amorphous spironolactone prepared by adsorption method using supercritical CO2.

PubMed

Jiang, Qikun; Li, Yuanyuan; Fu, Qiang; Geng, Yajie; Zhao, Juanhang; Ma, Panqin; Zhang, Tianhong

2015-02-01

The aim of this study was to improve the oral bioavailability of spironolactone (SP). SP was adsorbed on the fumed silica using supercritical CO2 (scCO2) technology and further compressed into tablets. The morphology was observed by scanning electron microscopy (SEM), and the crystalline form was investigated by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). The dissolution test was performed in water, 0.1 M HCl solution, pH 4.5 acetate buffers and pH 6.8 phosphate buffers using the paddle method. The pharmacokinetics was undertaken in six dogs in a crossover fashion. SP was successfully prepared into tablets and presented in amorphous state. SP-silica scCO2 tablets displayed higher dissolution profiles than SP-silica physical mixtures tablets in different media. The AUC0-t and Cmax of SP-silica supercritical CO2 was 1.61- and 1.52-fold greater than those of SP-silica physical mixtures (p < 0.05), respectively. It is a promising method in improving dissolution and bioavailability by adsorbing SP, a poorly soluble drug, on the fumed silica using rapid expansion of supercritical solutions.

An optimized immunohistochemistry protocol for detecting the guidance cue Netrin-1 in neural tissue.

PubMed

Salameh, Samer; Nouel, Dominique; Flores, Cecilia; Hoops, Daniel

2018-01-01

Netrin-1, an axon guidance protein, is difficult to detect using immunohistochemistry. We performed a multi-step, blinded, and controlled protocol optimization procedure to establish an efficient and effective fluorescent immunohistochemistry protocol for characterizing Netrin-1 expression. Coronal mouse brain sections were used to test numerous antigen retrieval methods and combinations thereof in order to optimize the stain quality of a commercially available Netrin-1 antibody. Stain quality was evaluated by experienced neuroanatomists for two criteria: signal intensity and signal-to-noise ratio. After five rounds of testing protocol variants, we established a modified immunohistochemistry protocol that produced a Netrin-1 signal with good signal intensity and a high signal-to-noise ratio. The key protocol modifications are as follows: •Use phosphate buffer (PB) as the blocking solution solvent.•Use 1% sodium dodecyl sulfate (SDS) treatment for antigen retrieval. The original protocol was optimized for use with the Netrin-1 antibody produced by Novus Biologicals. However, we subsequently further modified the protocol to work with the antibody produced by Abcam. The Abcam protocol uses PBS as the blocking solution solvent and adds a citrate buffer antigen retrieval step.

DNA stretching on the wall surfaces in curved microchannels with different radii

NASA Astrophysics Data System (ADS)

Hsieh, Shou-Shing; Wu, Fong-He; Tsai, Ming-Ju

2014-08-01

DNA molecule conformation dynamics and stretching were made on semi-circular surfaces with different radii (500 to 5,000 μm) in microchannels measuring 200 μm × 200 μm in cross section. Five different buffer solutions - 1× Tris-acetate-EDTA (TAE), 1× Tris-borate-EDTA (TBE), 1× Tris-EDTA (TE), 1× Tris-phosphate-EDTA (TPE), and 1× Tris-buffered saline (TBS) solutions - were used with a variety of viscosity such as 40, 60, and 80 cP, with resultant 10-4 ≤ Re ≤ 10-3 and the corresponding 5 ≤ Wi ≤ 12. The test fluids were seeded with JOJO-1 tracer particles for flow visualization and driven through the test channels via a piezoelectric (PZT) micropump. Micro particle image velocimetry (μPIV) measuring technique was applied for the centered-plane velocity distribution measurements. It is found that the radius effect on the stretch ratio of DNA dependence is significant. The stretch ratio becomes larger as the radius becomes small due to the larger centrifugal force. Consequently, the maximum stretch was found at the center of the channel with a radius of 500 μm.

Control of brown stain: in Eastern white pine

Treesearch

Robert E. Stutz; Peter Koch; Millard L. Oldham

1961-01-01

Degrade caused by brown stain and blue stain in eastern white pine was virtually eliminated by the use of sap stain chemicals and sodium azide. Combinations of buffered sodium azide with both sodium pentachlorophenate plus borax and buffered ethyl mercury phosphate were effective.

Developing procedures for the large-scale purification of human serum butyrylcholinesterase.

PubMed

Saxena, Ashima; Luo, Chunyuan; Doctor, Bhupendra P

2008-10-01

Human serum butyrylcholinesterase (Hu BChE) is the most viable candidate for the prophylactic treatment of organophosphate poisoning. A dose of 200 mg/70 kg is predicted to protect humans against 2x LD(50) of soman. Therefore, the aim of this study was to develop procedures for the purification of gram quantities of this enzyme from outdated human plasma or Cohn Fraction IV-4. The purification of Hu BChE was accomplished by batch adsorption on procainamide-Sepharose-CL-4B affinity gel followed by ion-exchange chromatography on a DEAE-Sepharose column. For the purification of enzyme from Cohn Fraction IV-4, it was resuspended in 25 mM sodium phosphate buffer, pH 8.0, and fat was removed by decantation, prior to batch adsorption on procainamide-Sepharose gel. In both cases, the procainamide gel was thoroughly washed with 25 mM sodium phosphate buffer, pH 8.0, containing 0.05 M NaCl, and the enzyme was eluted with the same buffer containing 0.1 M procainamide. The enzyme was dialyzed and the pH was adjusted to 4.0 before loading on the DEAE column equilibrated in sodium acetate buffer, pH 4.0. The column was thoroughly washed with 25 mM sodium phosphate buffer, pH 8.0 containing 0.05 M NaCl before elution with a gradient of 0.05-0.2M NaCl in the same buffer. The purity of the enzyme following these steps ranged from 20% to 40%. The purity of the enzyme increased to >90% by chromatography on an analytical procainamide affinity column. Results show that Cohn Fraction IV-4 is a much better source than plasma for the large-scale isolation of purified Hu BChE.

Dissolution enhancement of atorvastatin calcium by co-grinding technique.

PubMed

Prabhu, Priyanka; Patravale, Vandana

2016-08-01

Atorvastatin calcium (AC) is a BCS class II drug which shows poor bioavailability due to inadequate dissolution. Solid dispersions present a promising option to enhance the solubility of poorly soluble drugs. Co-grinding with hydrophilic excipients is an easy and economical technique to improve the solubility of poorly soluble drugs and is free from usage of organic solvents. The aim of the present study was to explore novel carrier VBP-1 (organosulphur compound) for formulating a solid dispersion by using a simple, commercially viable co-grinding technique to enhance the dissolution of AC and to develop an oral formulation of the same. Composition of the solid dispersion was optimized based on the release profile in pH 1.2 buffer. The optimized solid dispersion was further characterized for flow properties, DSC, FTIR spectroscopy, XRD, contact angle, SEM studies and release profile in phosphate buffer pH 6.8. The developed solid dispersion gave similar release profile as the innovator formulation (Lipitor® tablets) in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed solid dispersion was formulated into hard gelatin capsules (size 3). The developed capsules were found to give similar release as the innovator formulation in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed capsules were found to be stable for a period of 6 months. Anti-hyperlipidemic efficacy studies in rats showed higher reduction in cholesterol and triglyceride levels by the developed capsules in comparison to pure AC. In conclusion, novel carrier VBP-1 was successfully employed to enhance the dissolution of AC using co-grinding technique.

Automated Gravimetric Calibration to Optimize the Accuracy and Precision of TECAN Freedom EVO Liquid Handler

PubMed Central

Bessemans, Laurent; Jully, Vanessa; de Raikem, Caroline; Albanese, Mathieu; Moniotte, Nicolas; Silversmet, Pascal; Lemoine, Dominique

2016-01-01

High-throughput screening technologies are increasingly integrated into the formulation development process of biopharmaceuticals. The performance of liquid handling systems is dependent on the ability to deliver accurate and precise volumes of specific reagents to ensure process quality. We have developed an automated gravimetric calibration procedure to adjust the accuracy and evaluate the precision of the TECAN Freedom EVO liquid handling system. Volumes from 3 to 900 µL using calibrated syringes and fixed tips were evaluated with various solutions, including aluminum hydroxide and phosphate adjuvants, β-casein, sucrose, sodium chloride, and phosphate-buffered saline. The methodology to set up liquid class pipetting parameters for each solution was to split the process in three steps: (1) screening of predefined liquid class, including different pipetting parameters; (2) adjustment of accuracy parameters based on a calibration curve; and (3) confirmation of the adjustment. The run of appropriate pipetting scripts, data acquisition, and reports until the creation of a new liquid class in EVOware was fully automated. The calibration and confirmation of the robotic system was simple, efficient, and precise and could accelerate data acquisition for a wide range of biopharmaceutical applications. PMID:26905719

Black Phosphorus (BP) Nanodots for Potential Biomedical Applications.

PubMed

Lee, Hyun Uk; Park, So Young; Lee, Soon Chang; Choi, Saehae; Seo, Soonjoo; Kim, Hyeran; Won, Jonghan; Choi, Kyuseok; Kang, Kyoung Suk; Park, Hyun Gyu; Kim, Hee-Sik; An, Ha Rim; Jeong, Kwang-Hun; Lee, Young-Chul; Lee, Jouhahn

2016-01-13

Recently, the appeal of 2D black phosphorus (BP) has been rising due to its unique optical and electronic properties with a tunable band gap (≈0.3-1.5 eV). While numerous research efforts have recently been devoted to nano- and optoelectronic applications of BP, no attention has been paid to promising medical applications. In this article, the preparation of BP-nanodots of a few nm to <20 nm with an average diameter of ≈10 nm and height of ≈8.7 nm is reported by a modified ultrasonication-assisted solution method. Stable formation of nontoxic phosphates and phosphonates from BP crystals with exposure in water or air is observed. As for the BP-nanodot crystals' stability (ionization and persistence of fluorescent intensity) in aqueous solution, after 10 d, ≈80% at 1.5 mg mL(-1) are degraded (i.e., ionized) in phosphate buffered saline. They showed no or little cytotoxic cell-viability effects in vitro involving blue- and green-fluorescence cell imaging. Thus, BP-nanodots can be considered a promising agent for drug delivery or cellular tracking systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Role of protein concentration and protein-saliva interactions in the astringency of whey proteins at low pH.

PubMed

Kelly, M; Vardhanabhuti, B; Luck, P; Drake, M A; Osborne, J; Foegeding, E A

2010-05-01

Whey protein beverages are adjusted to pH <4.5 to enhance clarity and stability, but this pH level is also associated with increased astringency. The goal of this investigation was to determine the effects of protein concentration on astringency and interactions between whey and salivary proteins. Whey protein beverages containing 0.25 to 13% (wt/wt) beta-lactoglobulin and 0.017% (wt/wt) sucralose at pH 2.6 to 4.2 were examined using descriptive sensory analysis. Controls were similar pH phosphate buffers at phosphate concentrations equivalent to the amount of phosphoric acid required to adjust the pH of the protein solution. Changes in astringency with protein concentration depended on pH. At pH 3.5, astringency significantly increased with protein concentration from 0.25 to 4% (wt/wt) and then remained constant from 4 to 13% (wt/wt). Conversely, at pH 2.6, astringency decreased with an increase in protein concentration [0.5-10% (wt/wt)]. This suggests a complex relationship that includes pH and buffering capacity of the beverages. Furthermore, saliva flow rates increased with increasing protein concentrations, showing that the physiological conditions in the mouth change with protein concentration. Maximum turbidity of whey protein-saliva mixtures was observed between pH 4.6 and 5.2. Both sensory evaluation and in vitro study of interactions between beta-LG and saliva indicate that astringency of whey proteins is a complex process determined by the extent of aggregation occurring in the mouth, which depends on the whey protein beverage pH and buffering capacity in addition to saliva flow rate. Copyright 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effect of buffer and antioxidant on stability of a mercaptopurine suspension.

PubMed

Aliabadi, Hamidreza Montazeri; Romanick, Marcel; Desai, Sunil; Lavasanifar, Afsaneh

2008-03-01

The stability of standard and modified mercaptopurine suspensions when stored at room temperature and under refrigerated conditions to test the feasibility of increasing shelf life was studied. A 50-mg/mL mercaptopurine suspension was compounded by adding simple syrup, cherry syrup, and sterile water for irrigation to triturated mercaptopurine tablets for the initial reference formulation. Three additional formulations were prepared by adding an antioxidant (ascorbic acid 10 mg), a buffer (sodium phosphate monobasic monohydrate 500 mg), and a combination of antioxidant and buffer to the reference formulation. Each compounded batch was divided into two parts and stored in amber bottles at room temperature (19-23 degrees C) or under refrigerated conditions (4-8 degrees C). Analysis through high-performance liquid chromatography determined mercaptopurine levels after three and seven days and weekly thereafter for at least two weeks after shelf life was reached under specified storage conditions. Solutions with at least 93% of the original mercaptopurine concentration and with no observable sign of aggregation or cake formation were considered stable. The reference suspension of mercaptopurine showed an acceptable physical and chemical stability of up to 5 weeks when stored at room temperature. The addition of ascorbic acid extended the shelf life of the compounded suspension to 11 weeks. However, the addition of sodium phosphate monobasic did not improve the stability of mercaptopurine in the suspension. The results showed a higher stability for all formulations after storage at room temperature compared with those stored in a refrigerator. A standard oral suspension of mercaptopurine contained an acceptable drug concentration for up to 5 weeks when stored at room temperature. The addition of ascorbic acid at a concentration of 0.1% w/v to the standard formulation increased the suspension's shelf life at room temperature to 11 weeks.

Posttraining intraamygdala infusions of oxotremorine and propranolol modulate storage of memory for reductions in reward magnitude.

PubMed

Salinas, J A; Introini-Collison, I B; Dalmaz, C; McGaugh, J L

1997-07-01

These experiments examined the effects of posttraining intraamygdala administration of the muscarinic agonist, oxotremorine, and the beta-noradrenergic antagonist, propranolol, on memory for reduction in reward magnitude. Male Sprague-Dawley rats (175-200 g) implanted with bilateral intraamygdala cannulae were food deprived (maintained at 80% of body weight) and trained to run a straight alley (six trials/day) for either ten 45-mg food pellets (high reward) or one 45-mg food pellet (low reward) for 10 days. In Experiment One, the animals in the high-reward group were than shifted to a one-pellet reward and immediately given intraamygdala infusions (0.5 microliter/side) of either oxotremorine (10 ng) or phosphate buffer. Shifted training continued for 4 more days and no further injections were given. Shifted animals given the buffer solution displayed an increase in runway latencies but returned to preshift latencies by the fifth day of shifted training. In contrast, animals given oxotremorine exhibited increased latencies through the fifth day. In Experiment Two, rats were trained as in Experiment. One but immediately following the shift received intraamygdala infusions of oxotremorine (10 ng), propranolol (0.3 microgram), both, or phosphate buffer. Shifted vehicle-injected rats returned to preshift performance by the fifth day of shifted training. Shifted propranolol rats returned to preshift latencies by the third day of shifted training. In contrast, the shifted oxotremorine and the shifted oxotremorine/propranolol rats displayed longer latencies than unshifted controls through 5 days of shifted training. The findings indicate that the muscarinic cholinergic and beta-noradrenergic systems within the amygdala interact in regulating memory and support the view that noradrenergic influences are mediated through cholinergic activation.

Dynamics of gold nanoparticles in synthetic and biopolymer solutions

NASA Astrophysics Data System (ADS)

Kohli, Indermeet

Soft matter systems of colloidal particles, polymers, amphiphiles and liquid crystals are ubiquitous in our everyday life. Food, plastics, soap and even human body is comprised of soft materials. Research conducted to understand the behavior of these soft matter systems at molecular level is essential for many interdisciplinary fields of study as well as important for many technological applications. We used gold nanoparticles (Au NPs) to investigate the length-scale dependent dynamics in semidilute poly(ethylene glycol) (PEG)-water, bovine serum albumin (BSA)-phosphate buffer, dextran and particulate solutions. In case of PEG-water solutions, fluctuation correlation spectroscopy was used to measure the diffusion coefficients (D) of the NPs as a function of their radius, Ro (2.5-10 nm), PEG volume fraction, φ (0-0.37) and molecular weight, Mw (5 kg/mol and 35 kg/mol). Our results indicate that the radius of gyration, Rg of the polymer chain is the crossover length scale for the NPs experiencing nanoviscosity or macroviscosity. In BSA-phosphate buffer solutions, we observed a monolayer formation at the NP surface with a thickness of 3.8 nm. The thickness of the adsorbed layer was independent of NP size. Best fit was obtained by the anticooperative binding model with the Hill coefficient of n = 0.63. Dissociation constant (KD) increased with particle size indicating stronger interaction of BSA with smaller sized NPs. We also contrasted the diffusion of gold nanoparticles (AuNPs) in crowded solutions of randomly branched polymer (dextran) and rigid, spherical particles (silica) to understand the roles played by the probe size and structure of the crowding agent in determining the probe diffusion. AuNPs of two different sizes (2.5 nm & 10 nm), dextran of molecular weight 70 kDa and silica particles of radius 10 nm were used. Our results indicated that the AuNP diffusion can be described using the bulk viscosity of the matrix and hydrodynamically dextran behaved similar to soft colloid. In all situations, we observed normal diffusion except for 2.5 nm sized AuNP particles in dextran solution at higher volume fraction. This was caused by transient trapping of particles within the random branches. The results showed the importance of macromolecular architecture in determining the transport properties in intracellular matrix and in cells with spiny dendrites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vincent, S.; Daiwile, A.; Devi, S. S.

Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experimentsmore » was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. As a result, the comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.« less

Effect of the environment on wear ranking and corrosion of biomedical CoCrMo alloys.

PubMed

Muñoz, A Igual; Mischler, S

2011-03-01

The corrosion behaviour and the wear ranking of biomedical high carbon (HC) and low carbon (LC) CoCrMo alloys sliding against an alumina ball in four different simulated body fluids [NaCl and phosphate buffered solutions (PBS) with and without albumin] has been analyzed by tribocorrosion and electrochemical techniques. The effects of alloy and of albumin on corrosion depend on the base electrolyte: differences between LC and HC alloy were only observed in NaCl solutions but not in PBS. Albumin increased significantly corrosion of both alloys in PBS solutions while its effect in NaCl was smaller. The wear ranking of the HC and LC alloys also depends on the environment. In the present study, HC CoCrMo alloy had lower wear resistance in NaCl and PBS + albumin than the LC alloy, while no differences between both alloys were found in the other solutions. This was attributed to surface chemical effects affecting third body behaviour.

Study of a hydraulic dicalcium phosphate dihydrate/calcium oxide-based cement for dental applications.

PubMed

el-Briak, Hasna; Durand, Denis; Nurit, Josiane; Munier, Sylvie; Pauvert, Bernard; Boudeville, Phillipe

2002-01-01

By mixing CaHPO(4) x 2H(2)O (DCPD) and CaO with water or sodium phosphate buffers as liquid phase, a calcium phosphate cement was obtained. Its physical and mechanical properties, such as compressive strength, initial and final setting times, cohesion time, dough time, swelling time, dimensional and thermal behavior, and injectability were investigated by varying different parameters such as liquid to powder (L/P) ratio (0.35-0.7 ml g(-1)), molar calcium to phosphate (Ca/P) ratio (1.67-2.5) and the pH (4, 7, and 9) and the concentration (0-1 M) of the sodium phosphate buffer. The best results were obtained with the pH 7 sodium phosphate buffer at the concentration of 0.75 M. With this liquid phase, physical and mechanical properties depended on the Ca/P and L/P ratios, varying from 3 to 11 MPa (compressive strength), 6 to 10 min (initial setting time), 11 to 15 min (final setting time), 15 to 30 min (swelling time), 7 to 20 min (time of 100% injectability). The dough or working time was over 16 min. This cement expanded during its setting (1.2-5 % according to Ca/P and L/P ratios); this would allow a tight filling. Given the mechanical and rheological properties of this new DCPD/CaO-based cement, its use as root canal sealing material can be considered as classical calcium hydroxide or ZnO/eugenol-based pastes, without or with a gutta-percha point. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 447-453, 2002

Controlled release formulations of risperidone antipsychotic drug in novel aliphatic polyester carriers: Data analysis and modelling.

PubMed

Siafaka, Panoraia I; Barmpalexis, Panagiotis; Lazaridou, Maria; Papageorgiou, George Z; Koutris, Efthimios; Karavas, Evangelos; Kostoglou, Margaritis; Bikiaris, Dimitrios N

2015-08-01

In the present study a series of biodegradable and biocompatible poly(ε-caprolactone)/poly(propylene glutarate) (PCL/PPGlu) polymer blends were investigated as controlled release carriers of Risperidone drug (RISP), appropriate for transdermal drug delivery. The PCL/PPGlu carriers were prepared in different weight ratios. Miscibility studies of blends were evaluated through differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). Hydrolysis studies were performed at 37°C using a phosphate buffered saline solution. The prepared blends have been used for the preparation of RISP patches via solvent evaporation method, containing 5, 10 and 15wt% RISP. These formulations were characterized using FT-IR spectroscopy, DSC and WAXD in order to evaluate interactions taking place between polymer matrix and drug, as well as the dispersion and the physical state of the drug inside the polymer matrix. In vitro drug release studies were performed using as dissolution medium phosphate buffered saline simulating body fluids. It was found that in all cases controlled release formulations were obtained, while the RISP release varies due to the properties of the used polymer blend and the different levels of drug loading. Artificial Neural Networks (ANNs) were used for dissolution behaviour modelling showing increased correlation efficacy compared to Multi-Linear-Regression (MLR). Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of deferasirox in human plasma by short-end injection and sweeping with a field-amplified sample stacking and micellar electrokinetic chromatography.

PubMed

Lin, Hung-Ju; Hsieh, Kun-Pin; Chiou, Shyh-Shin; Kou, Hwang-Shang; Wu, Shou-Mei

2016-11-30

A field-amplified sample stacking-sweeping micellar electrokinetic chromatography with short-end injection was established for determination of deferasirox (DFX) in plasma. DFX was extracted from plasma and reconstituted with deionized water (lower conductivity solution). Capillary (effective length, 10cm) was filled with background electrolyte (40mM phosphate buffer, pH 4.5, containing 20% methanol). After sample loading from outlet end at 5psi for 15s, separation was carried out by applying high voltage at 15kV for 10min. Sodium dodecyl sulfate (SDS) was used to sweep DFX for enhancing sensitivity. The optimal CE separation conditions were 40mM phosphate buffer at pH 4.5 containing 100mM SDS and 20% methanol. The analysis time was about 3.5min for DFX. The calibration curve of DFX was ranged from 1 to 20μg/ml. The linearity (r) was more than 0.998. RSD and RE in intra- and inter-day assays were all below 12.14%. The limit of detection (LOD, S/N=3) for DFX was 0.3μg/ml. The sensitivity enhancement factor between sweeping-FASS MEKC and capillary zone electrophoresis is 3.3. Finally, the method was applied for determination of DFX in β-thalassemia patients. Copyright © 2016 Elsevier B.V. All rights reserved.

In-vitro evaluation of enteric coated insulin tablets containing absorption enhancer and enzyme inhibitor.

PubMed

Wong, Chun Y; Martinez, Jorge; Carnagarin, Revathy; Dass, Crispin R

2017-03-01

The aim of this study was to develop an enteric coated insulin tablet formulation using polymers, absorption enhancer and enzyme inhibitor, which protect the tablets in acidic pH and enhance systemic bioavailability. In this study, the influence of coating by cellulose acetate hydrogen phthalate solution and chosen excipients on Glut-4 transporter translocation in C2C12 skeletal muscle cells was examined. Following the determination of optimum number of coating layers, two dissolution buffers such as 0.01 m hydrochloric acid, pH 2, and 50 mm phosphate, pH 7.4, were employed to determine the in-vitro release of insulin. Insulin was protected by the coating during the dissolution process. Five (5-CL) coating layers and eight (8-CL) coating layers had minimal insulin release in hydrochloric acid, but not three (3-CL) coating layers. Glut-4 translocation in C2C12 cells was promoted by the chosen excipients. No detrimental metabolic effects were observed in these cells. To date, limited studies combine the overall effectiveness of multiple excipients. Our study showed that the coated tablets have an immediate release effect in phosphate buffer. In Glut-4 translocation assay, insulin was still functional after releasing from the tablet. Such tablet formulation can be potentially beneficial to type 1 diabetes patients. © 2017 Royal Pharmaceutical Society.

In silico and in vitro prediction of gastrointestinal absorption from potential drug eremantholide C.

PubMed

Caldeira, Tamires G; Saúde-Guimarães, Dênia A; Dezani, André B; Serra, Cristina Helena Dos Reis; de Souza, Jacqueline

2017-11-01

Analysis of the biopharmaceutical properties of eremantholide C, sesquiterpene lactone with proven pharmacological activity and low toxicity, is required to evaluate its potential to become a drug. Preliminary analysis of the physicochemical characteristics of eremantholide C was performed in silico. Equilibrium solubility was evaluated using the shake-flask method, at 37.0 °C, 100 rpm during 72 h in biorelevant media. The permeability was analysed using parallel artificial membrane permeability assay, at 37.0 °C, 50 rpm for 5 h. The donor compartment was composed of an eremantholide C solution in intestinal fluid simulated without enzymes, while the acceptor compartment consisted of phosphate buffer. Physicochemical characteristics predicted in silico indicated that eremantholide C has a low solubility and high permeability. In-vitro data of eremantholide C showed low solubility, with values for the dose/solubility ratio (ml): 9448.82, 10 389.61 e 15 000.00 for buffers acetate (pH 4.5), intestinal fluid simulated without enzymes (pH 6.8) and phosphate (pH 7.4), respectively. Also, it showed high permeability, with effective permeability of 30.4 × 10 -6 cm/s, a higher result compared with propranolol hydrochloride (9.23 × 10 -6 cm/s). The high permeability combined with its solubility, pharmacological activity and low toxicity demonstrate the importance of eremantholide C as a potential drug candidate. © 2017 Royal Pharmaceutical Society.

Electrochemical studies on zirconium and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in simulated physiologic media.

PubMed

Oliveira, Nilson T C; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

2005-09-01

Different electrochemical studies were carried out for Zr and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in solutions simulating physiologic media, Ringer and PBS (phosphate buffered saline) solutions. The results from rest-potential measurements showed that the three materials are spontaneously passivated in both solutions and that the Ti-50Zr alloy has the greatest tendency for spontaneous oxide formation. Some corrosion parameters (such as the pitting and repassivation potentials) were obtained via cyclic voltammetry in both solutions, revealing that the Ti-50Zr has the best corrosion protection while Zr has the worst. On the other hand, the pre-anodization (up to 8 V vs. SCE) of the alloys in a 0.15 mol/L Na2SO4 solution led to a significant improvement in their protection against pitting corrosion when exposed to the Ringer solution. Elemental analyses by EDX showed that during pitting corrosion, there is no preferential corrosion of any of the alloying elements (Zr, Ti, Nb). Copyright (c) 2005 Wiley Periodicals, Inc.

Signal Amplification in Field Effect-Based Sandwich Enzyme-Linked Immunosensing by Tuned Buffer Concentration with Ionic Strength Adjuster.

PubMed

Kumar, Satyendra; Kumar, Narendra; Panda, Siddhartha

2016-04-01

Miniaturization of the sandwich enzyme-based immunosensor has several advantages but could result in lower signal strength due to lower enzyme loading. Hence, technologies for amplification of the signal are needed. Signal amplification in a field effect-based electrochemical immunosensor utilizing chip-based ELISA is presented in this work. First, the molarities of phosphate buffer saline (PBS) and concentrations of KCl as ionic strength adjuster were optimized to maximize the GOx glucose-based enzymatic reactions in a beaker for signal amplification measured by change in the voltage shift with an EIS device (using 20 μl of solution) and validated with a commercial pH meter (using 3 ml of solution). The PBS molarity of 100 μM with 25 mM KCl provided the maximum voltage shift. These optimized buffer conditions were further verified for GOx immobilized on silicon chips, and similar trends with decreased PBS molarity were obtained; however, the voltage shift values obtained on chip reaction were lower as compared to the reactions occurring in the beaker. The decreased voltage shift with immobilized enzyme on chip could be attributed to the increased Km (Michaelis-Menten constant) values in the immobilized GOx. Finally, a more than sixfold signal enhancement (from 8 to 47 mV) for the chip-based sandwich immunoassay was obtained by altering the PBS molarity from 10 to 100 μM with 25 mM KCl.

Electrochemical study of the interaction between dsDNA and copper(I) using carbon paste and hanging mercury drop electrode.

PubMed

Stanić, Z; Girousi, S

2008-06-30

The interaction of copper(I) with double-stranded (ds) calf thymus DNA was studied in solution and at the electrode surface by means of transfer voltammetry using a carbon paste electrode (CPE) as working electrode in 0.2 M acetate buffer solution (pH 5.0). As a result of the interaction of Cu(I) between the base pairs of the dsDNA, the characteristic peaks of dsDNA, due to the oxidation of guanine and adenine, increased and after a certain concentration of Cu(I) a new peak at +1.37 V appeared, probably due to the formation of a purine-Cu(I) complex (dsDNA-Cu(I) complex). Accordingly, the interaction of copper(I) with calf thymus dsDNA was studied in solution as well as at the electrode surface using hanging mercury drop electrode (HMDE) by means of alternating current voltammetry (AC voltammetry) in 0.3 M NaCl and 50 mM sodium phosphate buffer (pH 8.5) as supporting electrolyte. Its interaction with DNA is shown to be time dependent. Significant changes in the characteristic peaks of dsDNA were observed after addition of higher concentration of Cu(I) to a solution containing dsDNA, as a result of the interaction between Cu(I) and dsDNA. All the experimental results indicate that Cu(I) can bind to DNA by electrostatic binding and form an association complex.

Phosphate-containing dialysis solution prevents hypophosphatemia during continuous renal replacement therapy

PubMed Central

BROMAN, M; CARLSSON, O; FRIBERG, H; WIESLANDER, A; GODALY, G

2011-01-01

Background Hypophosphatemia occurs in up to 80% of the patients during continuous renal replacement therapy (CRRT). Phosphate supplementation is time-consuming and the phosphate level might be dangerously low before normophosphatemia is re-established. This study evaluated the possibility to prevent hypophosphatemia during CRRT treatment by using a new commercially available phosphate-containing dialysis fluid. Methods Forty-two heterogeneous intensive care unit patients, admitted between January 2007 and July 2008, undergoing hemodiafiltration, were treated with a new Gambro dialysis solution with 1.2 mM phosphate (Phoxilium) or with standard medical treatment (Hemosol B0). The patients were divided into three groups: group 1 (n=14) receiving standard medical treatment and intravenous phosphate supplementation as required, group 2 (n=14) receiving the phosphate solution as dialysate solution and Hemosol B0 as replacement solution and group 3 (n=14) receiving the phosphate-containing solution as both dialysate and replacement solutions. Results Standard medical treatment resulted in hypophosphatemia in 11 of 14 of the patients (group 1) compared with five of 14 in the patients receiving phosphate solution as the dialysate solution and Hemosol B0 as the replacement solution (group 2). Patients treated with the phosphate-containing dialysis solution (group 3) experienced stable serum phosphate levels throughout the study. Potassium, ionized calcium, magnesium, pH, pCO2 and bicarbonate remained unchanged throughout the study. Conclusion The new phosphate-containing replacement and dialysis solution reduces the variability of serum phosphate levels during CRRT and eliminates the incidence of hypophosphatemia. PMID:21039362

Optimizing buffering chemistry to maintain near neutral pH of broiler feed during pre-enrichment for Salmonella.

PubMed

Berrang, M E; Cosby, D E; Cox, N A; Cason, J A; Richardson, K E

2015-12-01

Salmonella is a human pathogen that can accompany live broilers to the slaughter plant, contaminating fully processed carcasses. Feed is one potential source of Salmonella to growing broilers. Monitoring feed for the presence of Salmonella is part of good agricultural practice. The first step in culturing feed for Salmonella (which may be at low numbers and sub-lethally stressed) is to add it to a pre-enrichment broth which is incubated for 24 h. During the course of pre-enrichment, extraneous bacteria metabolize carbohydrates in some feed and excrete acidic byproducts, causing the pH to drop dramatically. An acidic pre-enrichment pH can injure or kill Salmonella resulting in a failure to detect, even if it is present and available to infect chickens. The objective of this study was to test an array of buffering chemistries to prevent formation of an injurious acidic environment during pre-enrichment of feed in peptone water. Five grams of feed were added to 45 mL of peptone water buffered with carbonate, Tris pH 8, and phosphate buffering ingredients individually and in combination. Feed was subjected to a pre-enrichment at 35°C for 24 h; pH was measured at 0, 18, and 24 h. Standard phosphate buffering ingredients at concentrations up to 4 times the normal formulation were unable to fully prevent acidic conditions. Likewise, carbonate and Tris pH 8 were not fully effective. The combination of phosphate, carbonate, and Tris pH 8 was the most effective buffer tested. It is recommended that a highly buffered pre-enrichment broth be used to examine feed for the presence of Salmonella. Published by Oxford University Press on behalf of Poultry Science Association 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Studies on the production of alkaline α-amylase from Bacillus subtilis CB-18.

PubMed

Nwokoro, Ogbonnaya; Anthonia, Odiase

2015-01-01

Amylases are among the main enzymes used in food and other industries. They hydrolyse starch molecules into polymers composing glucose units. Amylases have potential applications in a number of industrial processes including foods and pharmaceutical industries. Alkaline α-amylase has the potential of hydrolysing starch under alkaline pH and is useful in the starch and textile industries and as an ingredient of detergents. Amylases are produced from plants, however, microbial production processes have dominated applications in the industries. Optimization of microbial production processes can result in improved enzyme yields. Amylase activity was assayed by incubating the enzyme solution (0.5 ml) with 1% soluble starch (0.5 ml) in 0.1 M Tris/HCl buffer (pH 8.5). After 30 minutes, the reaction was stopped by the addition of 4 mL of 3,5-dinitrosalicylic acid (DNS) reagent then heated for 10 min in boiling water bath and cooled in a refrigerator. Absorbance readings were used to estimate the units of enzyme activity from glucose standard curve. Hydrolysed native starches from cassava, rice, corn, coco yam, maize and potato and soluble starch were adjusted to pH 8.5 prior to incubation with crude enzyme solution. Reducing sugars produced were therefore determined. The effect of pH on enzyme activity of the alkaline α-amylase was determined by using buffer solutions of different pH (potassium phosphate buffer, 6.0-7.0; Tris-HCl buffer 7.5 to 9.0 and carbonate/bicarbonate buffer, pH 9.5-11) for enzyme assay. The pH stability profile of the enzyme was determined by incubating 0.5 ml of α-amylase enzyme in 0.1 M Tris/HCl buffer (pH 8.5) and 0.5 ml of 1% (w/v) soluble starch (Merck) in 0.1 M Tris/HCl buffer (pH 8.5) for 3 h in various buffers. The effect of temperature on enzyme activity was studied by incubating 0.5 mL of the enzyme solution contained in the test tube and 0.5 mL of 1% soluble starch (Merck) solution prepared in 0.1 M Tris/HCl buffer (pH 8.5) for 3 h at various temperatures (25, 30, 35, 40, 45, 50, 55 and 60°C) in a thermo static water bath. The reactions were stopped by adding DNS reagent. The enzyme activity was therefore determined. Thermal stability was studied by incubating 0.5 ml of enzyme solution in 0.1 M Tris/HCl buffer (pH 8.5) and 0.5 ml of 1% (w/v) soluble starch (Merck) in 0.1 M Tris/HCl buffer (pH 8.5) for 3 h at various temperatures (20, 30, 40, 50, 60 and 70°C) for 60 min. The enzyme displayed optimal activity at pH 8.0 at which it produced maximum specific activity of 34.3 units/mg protein. Maximum stability was at pH 8.0 to 9.0. Maximum activity was observed at temperature of 50°C while thermo stability of the enzyme was observed at 40-50°C. The enzyme displayed a wide range of activities on starch and caused the release of 5.86, 4.75, 5.98, 3.44, 3.96, 8.84 mg/mL reducing sugar from cassava, potato, cocoyam, corn, rice and soluble starch respectively. This investigation reports some biochemical characterization of alkaline α-amylase from Bacillus subtilis CB-18. The substrate specificities of this enzyme on various starches suggested that the alkaline α-amylase enzyme had combined activities on raw and soluble starch.

Micro-reaction chamber electrodes for neural stimulation and recording.

PubMed

Shanmugasundaram, Balaji; Gluckman, Bruce J

2011-01-01

Biocompatible electrodes with smaller geometric area are preferred to improve the selectivity of the neural recording and stimulation applications. We introduce the concept of a micro-reaction chamber (μRC) in which a volume within the electrode back plane is used to confine and sequester the electrochemical reactions used for charge passage. The URC electrode design helps decrease impedance and improves the charge storage capacity without altering the geometry of the active site. Here we demonstrate that μRC electrodes fabricated from 50 μm diameter microwire have significantly improved charge storage capacity and lowered impedance at physiologically relevant frequencies in phosphate buffered saline solution compared with other designs.

Anodic stripping voltammetry of nickel ions and nickel hydroxide nanoparticles at boron-doped diamond electrodes

NASA Astrophysics Data System (ADS)

Musyarofah, N. R. R.; Gunlazuardi, J.; Einaga, Y.; Ivandini, T. A.

2017-04-01

Anodic stripping voltammetry (ASV) of nickel ions in phosphate buffer solution (PBS) have been investigated at boron-doped diamond (BDD) electrodes. The deposition potential at 0.1 V (vs. Ag/AgCl) for 300 s in 0.1 M PBS pH 3 was found as the optimum condition. The condition was applied for the determination of nickel contained in nickel hydroxide nanoparticles. A linear calibration curve can be achieved of Ni(OH)2-NPs in the concentration range of x to x mM with an estimated limit of detection (LOD) of 5.73 × 10-6 mol/L.

Structural and thermodynamic analysis of the hetero-association of theophylline with aromatic drug molecules

NASA Astrophysics Data System (ADS)

Andrejuk, D. D.; Hernandez Santiago, A. A.; Khomich, V. V.; Voronov, V. K.; Davies, D. B.; Evstigneev, M. P.

2008-10-01

The hetero-association of theophylline (THP) with other biologically-active aromatic molecules ( e.g. the anti-cancer drugs daunomycin and novantrone, the antibiotic norfloxacin, the vitamin flavin-mononucleotide and two mutagens ethidium bromide and proflavine) has been studied by NMR in aqueous-salt solution (0.1 M Na-phosphate buffer, p D 7.1). It was found that THP shows an essentially similar hetero-association ability as caffeine (CAF) towards aromatic drugs, except for novantrone (NOV), which has much less affinity to THP than CAF as a result of energetically unfavourable orthogonal orientation of the chromophores of THP and NOV in the hetero-complex.

Influence of vehicle properties and excipients on hydrolytic and photochemical stability of curcumin in preparations containing Pluronics: studies of curcumin and curcuminoids XLVIII.

PubMed

Singh, R; Kristensen, S; Tønnesen, H H

2013-03-01

The influence of vehicle properties and excipients on the hydrolytic and photochemical stability of curcumin in Pluronic preparations, and the interactions between curcumin and Pluronics was investigated. Curcumin was found to be degraded by general acid-base catalyzed hydrolytic degradation in alkaline preparations. The degradation rate of curcumin was higher in carbonate buffer than in phosphate buffer (pH 8.8), while it was higher in phosphate buffer than in citrate buffer (pH 7.8). At pH 8.0-8.8 the degradation rate of curcumin increased compared to preparations with pH <8.0. The stabilizing effect of the Pluronics against hydrolytic degradation of curcumin was only detectable at pH 8.0-8.8, and it was highest for F127 and lowest for P85, in phosphate buffer pH 8.8. An increase in the ionic strength increased the stabilization against hydrolytic degradation of curcumin by all Pluronics. Addition of ethanol decreased the hydrolytic stability of curcumin in all Pluronics. Addition of PEG 400 decreased the hydrolytic stability in preparation with either P123 or F127 while the degradation in preparations with P85 remained the same as in P85 preparations without PEG 400. Vehicle properties and excipients did not to any large degree influence the spectroscopic properties or the photostability of curcumin in Pluronic preparations. Photochemical half life of curcumin was in the minutes range. Spectrophotometric data indicate that Pluronic aggregates most likely solubilize curcumin through hydrophobic interactions, although hydrogen-bonding may also be involved.

Quantification of the internal resistance distribution of microbial fuel cells.

PubMed

Fan, Yanzhen; Sharbrough, Evan; Liu, Hong

2008-11-01

Identifying the limiting factors in a microbial fuel cell (MFC) system requires qualifying the contribution of each component of an MFC to internal resistance. In this study, a new method was developed to calculate the internal resistance distribution of an MFC. Experiments were conducted to identify the limiting factors in single-chamber MFCs by varying the anode surface areas, cathode surface areas, and phosphate buffer concentrations. For the MFCs with equally sized electrodes (7 cm2) and 200 mM phosphate buffer, the anode contributed just 5.4% of the internal resistance, while the cathode and the electrolyte each contributed 47.3%, indicating that the anode was not the limiting factor in power generation. The limitation of the cathode was further revealed by the 780% higher area-specific resistance (284.4 omega cm2) than the 32.3 omega cm2 of the anode. The electrolyte limitation was also evidenced by the greatly increased contribution of electrolyte in internal resistance from 47.3 to 78.2% when the concentration of phosphate buffer was decreased from 200 to 50 mM. An anodic power density of 6860 mW/m2 was achieved at a current density of 2.62 mA/cm2 using the MFCs with an anode/cathode area ratio of 1/14 and 200 mM phosphate buffer. The method was also successfully applied to analyze the internal resistance distribution of the two chamber MFCs from a previously reported study. The comparison of the internal resistances of the two air cathode systems indicates that the much lower resistances, including anode, cathode, and membrane resistances, contributed to the much better performance of the single-chamber MFCs than the two-chamber system.

A Study for Tooth Bleaching via Carbamide Peroxide-Loaded Hollow Calcium Phosphate Spheres.

PubMed

Qin, Tao; Mellgren, Torbjörn; Jefferies, Steven; Xia, Wei; Engqvist, Håkan

2016-12-26

The objective of this study was to investigate if a prolonged bleaching effect of carbamide peroxide-loaded hollow calcium phosphate spheres (HCPS) can be achieved. HCPS was synthesized via a hydrothermal reaction method. Carbamide peroxide (CP) was-loaded into HCPS by mixing with distilled water as solvent. We developed two bleaching gels containing CP-loaded HCPS: one gel with low HP concentration as at-home bleaching gel, and one with high HP concentration as in-office gel. Their bleaching effects on stained human permanent posterior teeth were investigated by measuring the color difference before and after bleaching. The effect of gels on rhodamine B degradation was also studied. To investigate the potential effect of remineralization of using HCPS, bleached teeth were soaked in phosphate buffer solution (PBS) containing calcium and magnesium ions. Both bleaching gels had a prolonged whitening effect, and showed a strong ability to degrade rhodamine B. After soaking in PBS for 3 days, remineralization was observed at the sites where HCPS attached to the teeth surface. CP-loaded HCPS could prolong the HP release behavior and improve the bleaching effect. HCPS was effective in increasing the whitening effect of carbamide peroxide and improving remineralization after bleaching process.

Effect of pH on uranium(VI) biosorption and biomineralization by Saccharomyces cerevisiae.

PubMed

Zheng, X Y; Shen, Y H; Wang, X Y; Wang, T S

2018-07-01

Biosorption of radionuclides by microorganisms is a promising and effective method for the remediation of contaminated areas. pH is the most important factor during uranium biosorption by Saccharomyces cerevisiae because the pH value not only affects the biosorption rate but also affects the precipitation structure. This study investigated the effect of pH on uranium (VI) biosorption and biomineralization by S. cerevisiae. Cells have the ability to buffer the solution to neutral, allowing the biosorption system to reach an optimal level regardless of the initial pH value. This occurs because there is a release of phosphate and ammonium ions during the interaction between cells and uranium. The uranyl and phosphate ions formed nano-particles, which is chernikovite H 2 (UO 2 ) 2 (PO 4 ) 2 ·8H 2 O (PDF #08-0296), on cell surface under the initial acidic conditions. However, under the initial alkaline conditions, the uranyl, phosphate and ammonium ions formed a large amount of scale-like precipitation, which is uramphite (NH 4 )(UO 2 )PO 4 ·3H 2 O (PDF #42-0384), evenly over on cell surface. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrospun PVA/Bentonite Nanocomposites Mats for Drug Delivery

PubMed Central

Ferrández-Rives, Mariola; Gómez Ribelles, José Luis

2017-01-01

Electrospun mats and films of polyvinyl alcohol (PVA) hydrogel are produced for drug delivery. To provide mechanical consistency to the gel a reinforcement by nanoclays is introduced in the polymer matrix. Four different suspensions of nanoparticles in the polymer solution are prepared in an adequate solvent. These suspensions are subjected to an electrospinning process to produce the nanofiber mat, while films are produced by casting. The influence of the process parameters over the nanofibers microstructure is analyzed by scanning electron microscopy (SEM). The effectiveness of nanoclay encapsulation in the nanocomposites is tested by a thermogravimetric analysis. A crosslinking reaction in solution is carried out to prevent the dissolution of the nanocomposites in aqueous media. A model protein (bovine serum albumin, BSA) is absorbed in the nanocomposites to characterize the release kinetics in phosphate-buffered saline (PBS). PMID:29261123

Solubilization of Therapeutic Agents in Micellar Nanomedicines

PubMed Central

Vuković, Lela; Madriaga, Antonett; Kuzmis, Antonina; Banerjee, Amrita; Tang, Alan; Tao, Kevin; Shah, Neil; Král, Petr; Onyuksel, Hayat

2014-01-01

We use atomistic molecular dynamics simulations to reveal the binding mechanisms of therapeutic agents in PEG-ylated micellar nanocarriers (SSM). In our experiments, SSM in buffer solutions can solubilize either ≈ 11 small bexarotene molecules or ≈ 6 (2 in low ionic strength buffer) human vasoactive intestinal peptide (VIP) molecules. Free energy calculations reveal that molecules of the poorly water soluble drug bexarotene can reside at the micellar ionic interface of the PEG corona, with their polar ends pointing out. Alternatively, they can reside in the alkane core center, where several bexarotene molecules can self-stabilize by forming a cluster held together by a network of hydrogen bonds. We also show that highly charged molecules, such as VIP, can be stabilized at the SSM ionic interface by Coulombic coupling between their positively charged residues and the negatively charged phosphate head-groups of the lipids. The obtained results illustrate that atomistic simulations can reveal drug solubilization character in nanocarriers and be used in efficient optimization of novel nanomedicines. PMID:24283508

Influence of sample preparation and identification of subcelluar structures in quantitative holographic phase contrast microscopy

NASA Astrophysics Data System (ADS)

Kemper, Björn; Schmidt, Lisa; Przibilla, Sabine; Rommel, Christina; Vollmer, Angelika; Ketelhut, Steffi; Schnekenburger, Jürgen; von Bally, Gert

2010-04-01

Digital holographic microscopy (DHM) provides label-free quantitative phase contrast with low demands on sample preparation. Nevertheless, for DHM measurements on fixed cells the mounting medium has to be considered while the phase contrast of living cells may be influenced by the used buffer solution. To quantify these effects, the maximum cell caused phase contrast and the visibility of the nucleoli were analyzed. A second aim of the study was to identify subcellular components in DHM phase contrast images. Therefore, comparative investigations using bright field imaging, DHM and fluorescence microscopy with 4',6- Diamidino-2-phenylindol (DAPI) staining were performed. DAPI-staining visualizes cell components containing DNA. The obtained results demonstrate exemplarily for two tumor cell lines that from DHM phase contrast images of fixed cells in phosphate buffer saline (PBS) cell thickness values are obtained which are comparable to living cells. Furthermore, it is shown that in many cases nucleus components can be identified only by DHM phase contrast.

The adsorption of tetracycline and vancomycin onto nanodiamond with controlled release.

PubMed

Giammarco, James; Mochalin, Vadym N; Haeckel, James; Gogotsi, Yury

2016-04-15

The unique properties and tailorable surface of detonation nanodiamonds have given rise to an abundance of potential biomedical applications. Very little is known about the details of adsorption/desorption equilibria of drugs on/from nanodiamonds with different purity, surface chemistry, and agglomeration state. The studies presented here delve into the details of adsorption and desorption of tetracycline (TET) and vancomycin (VAN) on nanodiamond, which are critically important for the rational design of the nanodiamond drug delivery systems. The nanodiamonds studied in these experiments were as-received (ND), purified and carboxyl terminated (ND-COOH), and aminated (ND-NH2). The monolayer capacities of the drugs loaded onto the nanodiamonds are reported herein using Langmuir and Freundlich isotherm models. The results from the desorption studies demonstrate that, by changing the pH environment of drug loaded nanodiamond using buffers of pH 4.09, 7.45, 8.02, and a phosphate buffered saline (PBS) solution, the drug release can effectively be triggered. Copyright © 2016 Elsevier Inc. All rights reserved.

Optimizing Fungal DNA Extraction Methods from Aerosol Filters

NASA Astrophysics Data System (ADS)

Jimenez, G.; Mescioglu, E.; Paytan, A.

2016-12-01

Fungi and fungal spores can be picked up from terrestrial ecosystems, transported long distances, and deposited into marine ecosystems. It is important to study dust-borne fungal communities, because they can stay viable and effect the ambient microbial populations, which are key players in biogeochemical cycles. One of the challenges of studying dust-borne fungal populations is that aerosol samples contain low biomass, making extracting good quality DNA very difficult. The aim of this project was to increase DNA yield by optimizing DNA extraction methods. We tested aerosol samples collected from Haifa, Israel (polycarbonate filter), Monterey Bay, CA (quartz filter) and Bermuda (quartz filter). Using the Qiagen DNeasy Plant Kit, we tested the effect of altering bead beating times and incubation times, adding three freeze and thaw steps, initially washing the filters with buffers for various lengths of time before using the kit, and adding a step with 30 minutes of sonication in 65C water. Adding three freeze/thaw steps, adding a sonication step, washing with a phosphate buffered saline overnight, and increasing incubation time to two hours, in that order, resulted in the highest increase in DNA for samples from Israel (polycarbonate). DNA yield of samples from Monterey (quart filter) increased about 5 times when washing with buffers overnight (phosphate buffered saline and potassium phophate buffer), adding a sonication step, and adding three freeze and thaw steps. Samples collected in Bermuda (quartz filter) had the highest increase in DNA yield from increasing incubation to 2 hours, increasing bead beating time to 6 minutes, and washing with buffers overnight (phosphate buffered saline and potassium phophate buffer). Our results show that DNA yield can be increased by altering various steps of the Qiagen DNeasy Plant Kit protocol, but different types of filters collected at different sites respond differently to alterations. These results can be used as preliminary results to continue developing fungi DNA extraction methods. Developing these methods will be important as dust storms are predicted to increase due to increased draughts and anthropogenic activity, and the fungal communities of these dust-storms are currently relatively understudied.

Novel ZnO/MgO/Fe2O3 composite optomagnetic nanoparticles.

PubMed

Kamińska, I; Sikora, B; Fronc, K; Dziawa, P; Sobczak, K; Minikayev, R; Paszkowicz, W; Elbaum, D

2013-05-15

A facile sol-gel synthesis of novel ZnO/MgO/Fe2O3 nanoparticles (NPs) is reported and their performance is compared to that of ZnO/MgO. Powder x-ray diffraction (XRD) patterns reveal the crystal structure of the prepared samples. The average particle size of the sample was found to be 4.8 nm. The optical properties were determined by UV-vis absorption and fluorescence measurements. The NPs are stable in biologically relevant solutions (phosphate buffered saline (PBS), 20 mM, pH = 7.0) contrary to ZnO/MgO NPs which degrade in the presence of inorganic phosphate. Superparamagnetic properties were determined with a superconducting quantum interference device (SQUID). Biocompatible and stable in PBS ZnO/MgO/Fe2O3 core/shell composite nanocrystals show luminescent and magnetic properties confined to a single NP at room temperature (19-24 ° C), which may render the material to be potentially useful for biomedical applications.

Growth of calcium phosphates on magnesium substrates for corrosion control in biomedical applications via immersion techniques.

PubMed

Shadanbaz, Shaylin; Walker, Jemimah; Staiger, Mark P; Dias, George J; Pietak, Alexis

2013-01-01

Magnesium (Mg) has been suggested as a revolutionary biodegradable replacement for current permanent metals used in orthopedic applications. Current investigations concentrate on the control of the corrosion rate to match bone healing. Calcium phosphate coatings have been a recent focus of these investigations through various coating protocols. Within this investigation, an in situ crystallization technique was utilized as an inexpensive and relatively simple method to produce a brushite and monetite coating on pure Mg. Coatings were characterized using energy dispersive spectroscopy, glancing angle X-ray diffraction and field emission scanning electron microscopy. Corrosion protection properties of the coatings were assessed in physiological buffers, Earles balanced salt solution, minimum essential media, and minimum essential media containing serum albumin, over a 4-week period. Using this novel coating protocol, our findings indicate brushite and monetite coated Mg to have significant corrosive protective effects when compared with its uncoated counterpart whilst maintaining high coating substrate adhesion, homogeneity, and reproducibility. Copyright © 2012 Wiley Periodicals, Inc.

Vehicle influence on permeation through intact and compromised skin.

PubMed

Gujjar, Meera; Banga, Ajay K

2014-09-10

The purpose of this study was to compare the transdermal permeation of a model compound, diclofenac diethylamine, from a hydrophilic and lipophilic vehicle across in vitro models simulating compromised skin. Mineral oil served as a lipophilic vehicle while 10mM phosphate buffered saline served as a hydrophilic vehicle. Compromised skin was simulated by tape stripping, delipidization, or microneedle application and compared with intact skin as a control. Transepidermal water loss was measured to assess barrier function. Skin compromised with tape stripping and delipidization significantly (p<0.05) increased permeation of diclofenac diethylamine compared to intact and microneedle treated skin with phosphate buffered saline vehicle. A similar trend in permeation was observed with mineral oil as the vehicle. For both vehicles, permeation across skin increased in the same order and correlated with degree of barrier impairment as indicated by transepidermal water loss values: intact

Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-L-alpha-phosphatidylcholine vesicles.

PubMed

Delanaye, Lisiane; Bahri, Mohamed Ali; Tfibel, Francis; Fontaine-Aupart, Marie-Pierre; Mouithys-Mickalad, Ange; Heine, Bélinda; Piette, Jacques; Hoebeke, Maryse

2006-03-01

The aggregation process of pyropheophorbide-a methyl ester (PPME), a second-generation photosensitizer, was investigated in various solvents. Absorption and fluorescence spectra showed that the photosensitizer was under a monomeric form in ethanol as well as in dimyristoyl-L-alpha-phosphatidylcholine liposomes while it was strongly aggregated in phosphate buffer. A quantitative determination of reactive oxygen species production by PPME in these solvents has been undertaken by electron spin resonance associated with spin trapping technique and absorption spectroscopy. In phosphate buffer, both electron spin resonance and absorption measurements led to the conclusion that singlet oxygen production was not detectable while hydroxyl radical production was very weak. In liposomes and ethanol, singlet oxygen and hydroxyl radical production increased highly; the singlet oxygen quantum yield was determined to be 0.2 in ethanol and 0.13 in liposomes. The hydroxyl radical production origin was also investigated. Singlet oxygen was formed from PPME triplet state deactivation in the presence of oxygen. Indeed, the triplet state formation quantum yield of PPME was found to be about 0.23 in ethanol, 0.15 in liposomes (too small to be measured in PBS).

Biochemical characteristics of glucose-6-phosphate dehydrogenase variants among the Malays of Singapore with report of a new non-deficient (GdSingapore) and three deficient variants.

PubMed

Saha, N; Hong, S H; Wong, H A; Jeyaseelan, K; Tay, J S

1991-12-01

Biochemical characteristics of one non-deficient fast G6PD variant (GdSingapore) and six different deficient variants (three new, two Mahidol, one each of Indonesian and Mediterranean) were studied among the Malays of Singapore. The GdSingapore variant had normal enzyme activity (82%) and fast electrophoretic mobilities (140% in TEB buffer, 160% in phosphate and 140% in Tris-HCl buffer systems respectively). This variant is further characterized by normal Km for G6P; utilization of analogues (Gal6P, 2dG6P; dAmNADP), heat stability and pH optimum. The other six deficient G6PD variants had normal electrophoretic mobility in TEB buffer with enzyme activities ranging from 1 to 12% of GdB+. The biochemical characteristics identity them to be 2 Mahidol, 1 Indonesian and 1 Mediterranean variants and three new deficient variants.

Determination and analysis of site-specific 125I decay-induced DNA double-strand break end-group structures.

PubMed

Datta, Kamal; Weinfeld, Michael; Neumann, Ronald D; Winters, Thomas A

2007-02-01

End groups contribute to the structural complexity of radiation-induced DNA double-strand breaks (DSBs). As such, end-group structures may affect a cell's ability to repair DSBs. The 3'-end groups of strand breaks caused by gamma radiation, or oxidative processes, under oxygenated aqueous conditions have been shown to be distributed primarily between 3'-phosphoglycolate and 3'-phosphate, with 5'-phosphate ends in both cases. In this study, end groups of the high-LET-like DSBs caused by 125I decay were investigated. Site-specific DNA double-strand breaks were produced in plasmid pTC27 in the presence or absence of 2 M DMSO by 125I-labeled triplex-forming oligonucleotide targeting. End-group structure was assessed enzymatically as a function of the DSB end to serve as a substrate for ligation and various forms of end labeling. Using this approach, we have demonstrated 3'-hydroxyl (3'-OH) and 3'-phosphate (3'-P) end groups and 5'-ends (> or = 42%) terminated by phosphate. A 32P postlabeling assay failed to detect 3'-phosphoglycolate in a restriction fragment terminated by the 125I-induced DNA double-strand break, and this is likely due to restricted oxygen diffusion during irradiation as a frozen aqueous solution. Even so, end-group structure and relative distribution varied as a function of the free radical scavenging capacity of the irradiation buffer.

Analysis of the difference in color development in the dye-binding method due to the kind of buffer solution.

PubMed

Suzuki, Yuji

2006-06-01

In a dye-binding method using a pH indicator, color development has reportedly been affected by the kind of buffer solution used in the color reagent. This phenomenon was analyzed by using a calculation based on the assumption that the anion of the buffer solution also reacts with protein. Color development decreases with increases in the anion concentration of the buffer solution and in the equilibrium constant of the reaction between the anion and protein. The differences in color development due to the kind of buffer solution can be attributed to differences in the equilibrium constant of the reaction forming the anion-protein complex and to the concentration of the anion between the buffer solutions.

The Role of Newly Discovered Exotoxin (S Toxin) in Pseudomonas aeruginosa Infections

DTIC Science & Technology

1979-08-01

sodium or potassium phosphate 6.0-8.0 N-2-hydroxyethylpiperazine-N’-2-ethanesulfonic acid (HEPES) 6.5-8.5 tris 7.0-9.5 sodium borate 7.5-9.5 sodium...was found to be variable with respect to whether sodium or potassium phosphate buffer was used. With sodium phosphate, virtually all the enzyme...activity bound was eluted between 20-100.2M phosphate at pH 6.8. With the potassium salt, elution occurs at 400-?00mM KP04. Since very little protein was

Fluorophotometric measurement of the buffering action of human tears in vivo.

PubMed

Yamada, M; Kawai, M; Mochizuki, H; Hata, Y; Mashima, Y

1998-10-01

The buffering action of human tears is thought to be important to keep its pH constant. We measured the change in pH in the precorneal tear film in vivo when the acidic solution is challenged, using a fluorophotometric technique. Twelve eyes from 6 healthy subjects were entered in this study. Each subject was pretreated with either one drop of 0.4% oxybuprocaine for once (light anesthesia), three times (deep anesthesia), or none (controls). The measurement was initiated by instilling 20 microl of 0.067 M phosphate buffer at pH 5.5 containing 2 mM bis-carboxyethyl-carboxyfluorescein free acid, a pH sensitive dye, into the subject's eye. The pH was determined by the ratio of fluorescent intensities at two excitation wavelengths (490 and 430 nm). pH recovery time (PHRT) as defined by the time required for pH to reach 95% of pH at equilibrium was used for the marker of tear buffering action. Tear turnover rate was also determined using the fluorescent decay curve at 430 nm, which was independent of pH, but dependent on dye concentration. Immediately after the instillation, the pH value in the tear film was around 6.0-6.5 in all cases. The tear film rapidly became more alkaline, reaching its normal value in 2.3 +/- 0.5 min in untreated eyes. The pretreatment with 0.4% oxybuprocaine retarded the neutralization process. A single regression analysis revealed that the PHRT had a significant negative correlation with the tear turnover rate (r = -0.78). Our results suggest that the neutralization process of tears largely depends on the tear turnover rate. The buffering action of tears in vivo consists of the tear turnover as well as its chemical buffering capacity.

Basal buffer systems for a newly glycosylated recombinant human interferon-β with biophysical stability and DoE approaches.

PubMed

Kim, Nam Ah; Song, Kyoung; Lim, Dae Gon; Hada, Shavron; Shin, Young Kee; Shin, Sangmun; Jeong, Seong Hoon

2015-10-12

The purpose of this study was to develop a basal buffer system for a biobetter version of recombinant human interferon-β 1a (rhIFN-β 1a), termed R27T, to optimize its biophysical stability. The protein was pre-screened in solution as a function of pH (2-11) using differential scanning calorimetry (DSC) and dynamic light scattering (DLS). According to the result, its experimental pI and optimal pH range were 5.8 and 3.6-4.4, respectively. Design of experiment (DoE) approach was developed as a practical tool to aid formulation studies as a function of pH (2.9-5.7), buffer (phosphate, acetate, citrate, and histidine), and buffer concentration (20 mM and 50 mM). This method employed a weight-based procedure to interpret complex data sets and to investigate critical key factors representing protein stability. The factors used were Tm, enthalpy, and relative helix contents which were obtained by DSC and Fourier Transform Infrared spectroscopy (FT-IR). Although the weights changed by three responses, objective functions from a set of experimental designs based on four buffers were highest in 20 mM acetate buffer at pH 3.6 among all 19 scenarios tested. Size exclusion chromatography (SEC) was adopted to investigate accelerated storage stability in order to optimize the pH value with susceptible stability since the low pH was not patient-compliant. Interestingly, relative helix contents and storage stability (monomer remaining) increased with pH and was the highest at pH 4.0. On the other hand, relative helix contents and thermodynamic stability decreased at pH 4.2 and 4.4, suggesting protein aggregation issues. Therefore, the optimized basal buffer system for the novel biobetter was proposed to be 20 mM acetate buffer at pH 3.8±0.2. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation, characterization and in vitro release study of carvacrol-loaded chitosan nanoparticles.

PubMed

Keawchaoon, Lalita; Yoksan, Rangrong

2011-05-01

The fabrication of carvacrol-loaded chitosan nanoparticles was achieved by a two-step method, i.e., oil-in-water emulsion and ionic gelation of chitosan with pentasodium tripolyphosphate. The obtained particles possessed encapsulation efficiency (EE) and loading capacity (LC) in the ranges of 14-31% and 3-21%, respectively, when the initial carvacrol content was 0.25-1.25 g/g of chitosan. The individual particles exhibited a spherical shape with an average diameter of 40-80 nm, and a positively charged surface with a zeta potential value of 25-29 mV. The increment of initial carvacrol content caused a reduction of surface charge. Carvacrol-loaded chitosan nanoparticles showed antimicrobial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli with an MIC of 0.257 mg/mL. The release of carvacrol from chitosan nanoparticles reached plateau level on day 30, with release amounts of 53% in acetate buffer solution with pH of 3, and 23% and 33% in phosphate buffer solutions with pH of 7 and 11, respectively. The release mechanism followed a Fickian behavior. The release rate was superior in an acidic medium to either alkaline or neutral media, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Bacterial colonization on coated and uncoated orthodontic wires: A prospective clinical trial.

PubMed

Raji, Seyed Hamid; Shojaei, Hasan; Ghorani, Parinaz Saeidi; Rafiei, Elahe

2014-11-01

The advantages of coated orthodontic wires such as esthetic and their effects on reduced friction, corrosion and allergic reaction and the significant consequences of plaque accumulation on oral health encouraged us to assess bacterial colonization on these wires. A total of 18 (9 upper and 9 lower) epoxy resin coated 16 × 22 nickel-titanium wires (Spectra, GAC, USA) and 18 (9 upper and 9 lower) non-coated 16 × 22 nickel-titanium wires (Sentalloy, GAC, USA) with isolated packages were selected and sterilized before application. The samples were divided randomly between upper and lower arches in 18 patients and hence that every patient received one coated and one uncoated wire at the same time. Samples were removed and cut in equal lengths after 3 weeks and placed in phosphate buffered saline buffer. After separation of bacteria in trypsin and ethylenediaminetetraacetic acid solution, the diluted solution was cultured in blood agar and bacterial colony forming units were counted. Finally, the data was analyzed using the paired t-test and the significance was set at 0.05. Mean of bacterial colonization on uncoated wires was more than that of coated wires (P < 0.001). Bacterial plaque accumulation on epoxy resin coated nickel-titanium orthodontic wires is significantly lower than uncoated nickel-titanium wires.

DNA stretching on the wall surfaces in curved microchannels with different radii.

PubMed

Hsieh, Shou-Shing; Wu, Fong-He; Tsai, Ming-Ju

2014-01-01

DNA molecule conformation dynamics and stretching were made on semi-circular surfaces with different radii (500 to 5,000 μm) in microchannels measuring 200 μm × 200 μm in cross section. Five different buffer solutions - 1× Tris-acetate-EDTA (TAE), 1× Tris-borate-EDTA (TBE), 1× Tris-EDTA (TE), 1× Tris-phosphate-EDTA (TPE), and 1× Tris-buffered saline (TBS) solutions - were used with a variety of viscosity such as 40, 60, and 80 cP, with resultant 10(-4) ≤ Re ≤ 10(-3) and the corresponding 5 ≤ Wi ≤ 12. The test fluids were seeded with JOJO-1 tracer particles for flow visualization and driven through the test channels via a piezoelectric (PZT) micropump. Micro particle image velocimetry (μPIV) measuring technique was applied for the centered-plane velocity distribution measurements. It is found that the radius effect on the stretch ratio of DNA dependence is significant. The stretch ratio becomes larger as the radius becomes small due to the larger centrifugal force. Consequently, the maximum stretch was found at the center of the channel with a radius of 500 μm.

DNA stretching on the wall surfaces in curved microchannels with different radii

PubMed Central

2014-01-01

DNA molecule conformation dynamics and stretching were made on semi-circular surfaces with different radii (500 to 5,000 μm) in microchannels measuring 200 μm × 200 μm in cross section. Five different buffer solutions - 1× Tris-acetate-EDTA (TAE), 1× Tris-borate-EDTA (TBE), 1× Tris-EDTA (TE), 1× Tris-phosphate-EDTA (TPE), and 1× Tris-buffered saline (TBS) solutions - were used with a variety of viscosity such as 40, 60, and 80 cP, with resultant 10−4 ≤ Re ≤ 10−3 and the corresponding 5 ≤ Wi ≤ 12. The test fluids were seeded with JOJO-1 tracer particles for flow visualization and driven through the test channels via a piezoelectric (PZT) micropump. Micro particle image velocimetry (μPIV) measuring technique was applied for the centered-plane velocity distribution measurements. It is found that the radius effect on the stretch ratio of DNA dependence is significant. The stretch ratio becomes larger as the radius becomes small due to the larger centrifugal force. Consequently, the maximum stretch was found at the center of the channel with a radius of 500 μm. PMID:25147488

Effect of pH and the role of organic matter in the adsorption of isoproturon on soils.

PubMed

Ertli, Tímea; Marton, Aurél; Földényi, Rita

2004-11-01

Equilibrium measurements were carried out with the herbicide isoproturon on natural adsorbents (brown forest-, chernozem-, sandy soils and quartz) in different buffered media (pH 5, 7, 8 phosphate buffer). Adsorption isotherms were fitted by a multi-step adsorption equation providing numerical information used in the environmental propagation models and risk assessment works. In the adsorption of the slightly polar isoproturon the dissolved organic matter of the soil and the pH play an important role. At molecular level, results are interpreted by taking into consideration the hydrophobic interaction and the formation of hydrogen bonds between the surface and the solute. The observed adsorption behavior indicates that the organic matter content of the soils and its soluble fulvic acid, alkaline soluble humic acid and insoluble humin fractions were considerable different. The chernozem soil containing the highest amount of insoluble organic fraction proved to be a very efficient adsorbent. The brown forest and the sandy soils exhibit rather similar adsorbent properties but at pH 7 the latter containing more fulvic acid adsorbs less isoproturon due to the enhanced solubility of the soil organic matter. In alkaline conditions the negatively charged solute and the surface repel each other and the hydrophobic interactions are also weaker than in neutral media.

A Phos-tag-based magnetic-bead method for rapid and selective separation of phosphorylated biomolecules.

PubMed

Tsunehiro, Masaya; Meki, Yuma; Matsuoka, Kanako; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

2013-04-15

A simple and efficient method based on magnetic-bead technology has been developed for the separation of phosphorylated and nonphosphorylated low-molecular-weight biomolecules, such as nucleotides, phosphorylated amino acids, or phosphopeptides. The phosphate-binding site on the bead is an alkoxide-bridged dinuclear zinc(II) complex with 1,3-bis(pyridin-2-ylmethylamino)propan-2-olate (Phos-tag), which is linked to a hydrophilic cross-linked agarose coating on a magnetic core particle. All steps for the phosphate-affinity separation are conducted in buffers of neutral pH with 50 μL of the magnetic beads in a 1.5-mL microtube. The entire separation protocol for phosphomonoester-type compounds, from addition to elution, requires less than 12 min per sample if the buffers and the zinc(II)-bound Phos-tag magnetic beads have been prepared in advance. The phosphate-affinity magnetic beads are reusable at least 15 times without a decrease in their phosphate-binding ability and they are stable for three months in propan-2-ol. Copyright © 2013 Elsevier B.V. All rights reserved.

Cullin 5 Expression in the Rat: Cellular and Tissue Distribution, and Changes in Response to Water Deprivation and Hemorrhagic Shock

DTIC Science & Technology

2003-02-28

of Health p53 tumor suppressor PBS phosphate buffered saline PCO2 partial pressure of carbon dioxide PO2 partial pressure of oxygen PCR...buffered saline TTBS tween-20 tris buffered saline TonEBP tonicity-response enhancer binding protein TSNRP TriService Nursing Research Program...growth and metabolism (Hochstrasser, 1995; Deshaies, 1999). Although traditionally seen as no more than a means of eliminating no longer needed

The Effects of pH on the Growth and Aspect Ratio of Chicken Egg White Lysozyme Crystals Prepared in Different Buffers

NASA Technical Reports Server (NTRS)

Gibson, U. J.; Horrell, E. E.; Kou, Y.; Pusey, Marc

2000-01-01

We have measured the nucleation and aspect ratio of CEWL crystals grown by vapor diffusion in acetate, butyrate, carbonate, succinate, and phosphate buffers in a range of pH spanning the pK(sub a) of these buffers. The nucleation numbers drop off significantly in the vicinity of pK(sub a) for each of the buffers except the phosphate system, in which we used only the pH range around the second titration point(pK2). There is a concomitant increase in the sizes of the crystals. Some typical nucleation number results are shown. These data support and extend other observations. In addition, we have examined changes in aspect ratio which accompany the suppression of nucleation within each buffer system. The length of the face in the [001] direction was measured, and compared to the width of the (110) face in the [110] type directions. We find that while the aspect ratio of the crystals is affected by pH, it is dominated by a correlation with the size of the crystals. Small crystals are longer in the [0011 direction than crystals that are larger (higher pH within a buffer system). This relationship is found to hold independent of the choice of buffer. These results are consistent with those of Judge et al, who used a batch process which resulted in uniform sizing of crystals at each pH. In these experiments, we specifically avoid agitating the protein/salt buffer mixture when combining the two. This permits the formation of a range of sizes at a given pH. The results for a .05 M acetate 5% NaCl buffer are also shown. We will discuss these results in light of a growth model.

ROBUST: The ROle of BUffering capacities in STabilising coastal lagoon ecosystems

NASA Astrophysics Data System (ADS)

de Wit, Rutger; Stal, Lucas J.; Lomstein, Bente Aa.; Herbert, Rodney A.; van Gemerden, Hans; Viaroli, Pierluigi; Cecherelli, Victor-Ugo; Rodríguez-Valera, Francisco; Bartoli, Marco; Giordani, Gianmarco; Azzoni, Roberta; Schaub, Bart; Welsh, David T.; Donnelly, Andrew; Cifuentes, Ana; Antón, Josefa; Finster, Kai; Nielsen, Lise B.; Pedersen, Anne-Grethe Underlien; Neubauer, Anne Turi; Colangelo, Marina A.; Heijs, Sander K.

2001-12-01

"Buffer capacities" has been defined in ecology as a holistic concept (e.g., Integration of Ecosystem Theories: A Pattern, second ed. Kluwer, Dordrecht, 1997, 388pp), but we show that it can also be worked out in mechanistic studies. Our mechanistic approach highlights that "buffering capacities" can be depleted progressively, and, therefore, we make a distinction between current and potential "buffering capacities". We have applied this concept to understand the limited "local stability" in seagrass ecosystems and their vulnerability towards structural changes into macro-algal dominated communities. We explored the following processes and studied how they confer buffering capacities to the seagrass ecosystem: (i) net autotrophy is persistent in Zostera noltii meadows where plant assimilation acts as a sink for nutrients, this contrasted with the Ulva system that shifted back and forth between net autotrophy and net heterotrophy; (ii) the Z. noltii ecosystem possesses a certain albeit rather limited capacity to modify the balance between nitrogen fixation and denitrification, i.e., it was found that in situ nitrogen fixation always exceeded denitrification; (iii) the nitrogen demand of organoheterotrophic bacteria in the sediment results in nitrogen retention of N in the sediment and hence a buffer against release of nitrogen compounds from sediments, (iv) habitat diversification in seagrass meadows provides shelter for meiofauna and hence buffering against adverse conditions, (v) sedimentary iron provides a buffer against noxious sulfide (note: bacterial sulfide production is enhanced in anoxic sediment niches by increased organic matter loading). On the other hand, in the coastal system we studied, sedimentary iron appears less important as a redox-coupled buffer system against phosphate loading. This is because most inorganic phosphate is bound to calcium rather than to iron. In addition, our studies have highlighted the importance of plant-microbe interactions in the seagrass meadows.

Transdermal delivery of forskolin from emulsions differing in droplet size.

PubMed

Sikora, Elżbieta; Llinas, Meritxell; Garcia-Celma, Maria Jose; Escribano, Elvira; Solans, Conxita

2015-02-01

The skin permeation of forskolin, a diterpene isolated from Coleus forsholii, was studied using oil in water (O/W) emulsions as delivery formulations and also an oil solution for comparative purposes. Two forskolin-loaded emulsions of water/Brij 72:Symperonic A7/Miglyol 812:Isohexadecane, at 0.075 wt% forskolin concentration were prepared with the same composition and only differing in droplet size (0.38 μm and 10 μm). The emulsions showed high kinetic stability at 25 °C. In vitro study of forskolin penetration through human skin was carried out using the MicroettePlus(®) system. The concentration of the active in the receptor solution (i.e. ethanol/phosphate buffer 40/60, v/v) was analyzed by high performance liquid chromatography with UV detection. The obtained results showed that forskolin permeation from the emulsions and the oil solution, through human skin, was very high (up to 72.10%), and no effect of droplet size was observed. Copyright © 2015 Elsevier B.V. All rights reserved.

Bio-sorbable, liquid electrolyte gated thin-film transistor based on a solution-processed zinc oxide layer.

PubMed

Singh, Mandeep; Palazzo, Gerardo; Romanazzi, Giuseppe; Suranna, Gian Paolo; Ditaranto, Nicoletta; Di Franco, Cinzia; Santacroce, Maria Vittoria; Mulla, Mohammad Yusuf; Magliulo, Maria; Manoli, Kyriaki; Torsi, Luisa

2014-01-01

Among the metal oxide semiconductors, ZnO has been widely investigated as a channel material in thin-film transistors (TFTs) due to its excellent electrical properties, optical transparency and simple fabrication via solution-processed techniques. Herein, we report a solution-processable ZnO-based thin-film transistor gated through a liquid electrolyte with an ionic strength comparable to that of a physiological fluid. The surface morphology and chemical composition of the ZnO films upon exposure to water and phosphate-buffered saline (PBS) are discussed in terms of the operation stability and electrical performance of the ZnO TFT devices. The improved device characteristics upon exposure to PBS are associated with the enhancement of the oxygen vacancies in the ZnO lattice due to Na(+) doping. Moreover, the dissolution kinetics of the ZnO thin film in a liquid electrolyte opens the possible applicability of these devices as an active element in "transient" implantable systems.

Effect of degree of esterification of pectin and calcium amount on drug release from pectin-based matrix tablets.

PubMed

Sungthongjeen, Srisagul; Sriamornsak, Pornsak; Pitaksuteepong, Tasana; Somsiri, Atawit; Puttipipatkhachorn, Satit

2004-02-12

The aim of this work was to assess the effect of 2 formulation variables, the pectin type (with different degrees of esterification [DEs]) and the amount of calcium, on drug release from pectin-based matrix tablets. Pectin matrix tablets were prepared by blending indomethacin (a model drug), pectin powder, and various amounts of calcium acetate and then tableting by automatic hydraulic press machine. Differential scanning calorimetry, powder x-ray diffraction, and Fourier transformed-infrared spectroscopy studies of the compressed tablets revealed no drug-polymer interaction and the existence of drug with low crystallinity. The in-vitro release studies in phosphate buffer (United States Pharmacopeia) and tris buffer indicated that the lower the DE, the greater the time for 50% of drug release (T50). This finding is probably because of the increased binding capacity of pectin to calcium. However, when the calcium was excluded, the pectins with different DEs showed similar release pattern with insignificant difference of T50. When the amount of calcium acetate was increased from 0 to 12 mg/tablet, the drug release was significantly slower. However, a large amount of added calcium (ie, 24 mg/tablet) produced greater drug release because of the partial disintegration of tablets. The results were more pronounced in phosphate buffer, where the phosphate ions induced the precipitation of calcium phosphate. In conclusion, both pectin type and added calcium affect the drug release from the pectin-based matrix tablets.

Formulation and synthesis of hydrogels having lower critical solution temperature near body temperature

NASA Astrophysics Data System (ADS)

Abidin, A. Z.; Graha, H. P. R.; Trirahayu, D. A.

2017-07-01

Copolymerization between bacterial cellulose nanocrystal (CN) and methyl cellulose (MC) was carried out using UV light to produce a biocompatible hydrogel at body temperature and liquid at room temperature. Viscosity and salt effect of the MC and copolymer solution at room temperature and its Lower Critical Solution Temperature (LCST) were evaluated. The analysis showed that the higher concentration of methyl cellulose and salt content in the solution produced lower LCST and higher solution viscosity. All samples of polymer solution with MC concentrations of 1 and 2% have a viscosity less than 5000 cP at room temperature. The solutions with MC concentration of 1, 2, and 3% have respectively LCST of 59, 58, and 57°C, while its copolymer solutions with CN concentration of 0.1, 0.3, and 0.5% have respectively LCST of 55, 51, and 41°C. The salt addition to the solution of MC-CN copolymer with concentrations of 1x and 1.5x Phosphat Buffered Saline (PBS) produces respectively LCST of 47 and 38°C. The results suggest that the copolymer solution of MC-CN could produce a lower LCST and the addition of salt could amplify the effect of LCST decrease that can be used to produce a biocompatible hydrogel with LCST as close as body temperature.

Electrocatalytic activity of spots of electrodeposited noble-metal catalysts on carbon nanotubes modified glassy carbon.

PubMed

Chen, Xingxing; Eckhard, Kathrin; Zhou, Min; Bron, Michael; Schuhmann, Wolfgang

2009-09-15

A strategy for the screening of the electrocatalytic activity of electrocatalysts for possible application in fuel cells and other devices is presented. In this approach, metal nanoclusters (Pt, Au, Ru, and Rh and their codeposits) were prepared using a capillary-based droplet-cell by pulsed electrodeposition in a diffusion-restricted viscous solution. A glassy carbon surface was modified with carbon nanotubes (CNTs) by electrophoretic accumulation and was used as substrate for metal nanoparticle deposition. The formed catalyst spots on the CNT-modified glassy carbon surface were investigated toward their catalytic activity for oxygen reduction as a test reaction employing the redox competition mode of scanning electrochemical microscopy (RC-SECM). Qualitative information on the electrocatalytic activity of the catalysts was obtained by varying the potential applied to the substrate; semiquantitative evaluation was based on the determination of the electrochemically deposited catalyst loading by means of the charge transferred during the metal nanoparticle deposition. Qualitatively, Au showed the highest electrocatalytic activity toward the oxygen reduction reaction (ORR) in phosphate buffer among all investigated single metal catalysts which was attributed to the much higher loading of Au achieved during electrodeposition. Coelectrodeposited Au-Pt catalysts showed a more positive onset potential (-150 mV in RC-SECM experiments) of the ORR in phosphate buffer at pH 6.7. After normalizing the SECM image by the charge during the metal nanocluster deposition which represents the mass loading of the catalyst, Ru showed a higher electrocatalytic activity toward the ORR than Au.

Development and validation of a liquid chromatographic method for the simultaneous determination of aniracetam and its related substances in the bulk drug and a tablet formulation.

PubMed

Papandreou, Georgios; Zorpas, Kostas; Archontaki, Helen

2011-11-01

Simultaneous determination of aniracetam and its related impurities (2-pyrrolidinone, p-anisic acid, 4-p-anisamidobutyric acid and (p-anisoyl)-4-methyl-2-pyrrolidinone) was accomplished in the bulk drug and in a tablet formulation using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS-CN column (150 mm × 4.0 mm, 5 μm) using a gradient elution program with solvent A composed of phosphate buffer (pH 4.0; 0.010 M) and solvent B of acetonitrile-phosphate buffer (pH 4.0; 0.010 M) (90:10, v/v). The flow rate of the mobile phase was 1.0 mL min(-1) and the total elution time, including the column re-equilibration, was approximately 20 min. The UV detection wavelength was varied appropriately among 210, 250 and 280 nm. Injection volume was 20 μL and experiments were conducted at ambient temperature. The developed method was validated in terms of system suitability, selectivity, linearity, range, precision, accuracy, limits of detection and quantification for the impurities, short term and long term stability of the analytes in the prepared solutions and robustness, following the ICH guidelines. Therefore, the proposed method was suitable for the simultaneous determination of aniracetam and its studied related impurities. Copyright © 2011 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winterbourn, C.C.; Sutton, H.C.

O2- was produced by gamma irradiation of formate solutions, by the action of xanthine oxidase on hypoxanthine and O2, and by the action of ferredoxin reductase on NADPH and paraquat in the presence of O2. Its reaction with H2O2 and various iron chelates was studied. Oxidation of deoxyribose to thiobarbituric acid-reactive products that was appropriately inhibited by OH. scavengers, or formate oxidation to CO2, was used to detect OH(.). With each source of O2-, and by these criteria, Fe(EDTA) efficiently catalyzed this (Haber-Weiss) reaction, but little catalysis was detectable with iron bound to DTPA, citrate, ADP, ATP, or pyrophosphate, ormore » without chelator in phosphate buffer. O2- produced from xanthine oxidase, but not from the other sources, underwent another iron-dependent reaction with H2O2, to produce an oxidant that did not behave as free OH(.). It was formed in phosphate or bicarbonate buffer, and caused deoxyribose oxidation that was readily inhibited by mannitol or Tris, but not by benzoate, formate, or dimethyl sulfoxide. It did not oxidize formate to CO2. Addition of EDTA changed the pattern of inhibition to that expected for a reaction of OH(.). The other chelators all inhibited deoxyribose oxidation, provided their concentrations were high enough. The results are compatible with iron bound to xanthine oxidase catalyzing production of a strong oxidant (which is not free OH.) from H2O2 and O2- produced by the enzyme.« less

Preparation of molecularly imprinted polymers for strychnine by precipitation polymerization and multistep swelling and polymerization and their application for the selective extraction of strychnine from nux-vomica extract powder.

PubMed

Nakamura, Yukari; Matsunaga, Hisami; Haginaka, Jun

2016-04-01

Monodisperse molecularly imprinted polymers for strychnine were prepared by precipitation polymerization and multistep swelling and polymerization, respectively. In precipitation polymerization, methacrylic acid and divinylbenzene were used as a functional monomer and crosslinker, respectively, while in multistep swelling and polymerization, methacrylic acid and ethylene glycol dimethacrylate were used as a functional monomer and crosslinker, respectively. The retention and molecular recognition properties of the molecularly imprinted polymers prepared by both methods for strychnine were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase by liquid chromatography. In addition to shape recognition, ionic and hydrophobic interactions could affect the retention of strychnine in low acetonitrile content. Furthermore, molecularly imprinted polymers prepared by both methods could selectively recognize strychnine among solutes tested. The retention factors and imprinting factors of strychnine on the molecularly imprinted polymer prepared by precipitation polymerization were 220 and 58, respectively, using 20 mM sodium phosphate buffer (pH 6.0)/acetonitrile (50:50, v/v) as a mobile phase, and those on the molecularly imprinted polymer prepared by multistep swelling and polymerization were 73 and 4.5. These results indicate that precipitation polymerization is suitable for the preparation of a molecularly imprinted polymer for strychnine. Furthermore, the molecularly imprinted polymer could be successfully applied for selective extraction of strychnine in nux-vomica extract powder. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ATP-stabilized amorphous calcium carbonate nanospheres and their application in protein adsorption.

PubMed

Qi, Chao; Zhu, Ying-Jie; Lu, Bing-Qiang; Zhao, Xin-Yu; Zhao, Jing; Chen, Feng; Wu, Jin

2014-05-28

Calcium carbonate is a common substance found in rocks worldwide, and is the main biomineral formed in shells of marine organisms and snails, pearls and eggshells. Amorphous calcium carbonate (ACC) is the least stable polymorph of calcium carbonate, which is so unstable under normal conditions that it is difficult to be prepared in vitro because it rapidly crystallizes to form one of the more stable polymorphs in aqueous solution. Herein, we report the successful synthesis of highly stable ACC nanospheres in vitro using adenosine 5'-triphosphate disodium salt (ATP) as a stabilizer. The effect of ATP on the stability of ACC nanospheres is investigated. Our experiments show that ATP plays an unique role in the stabilization of ACC nanospheres in aqueous solution. Moreover, the as-prepared ACC nanospheres are highly stable in phosphate buffered saline for a relatively long period of time (12 days) even under relatively high concentrations of calcium and phosphate ions. The cytotoxicity tests show that the as-prepared highly stable ACC nanospheres have excellent biocompatibility. The highly stable ACC nanospheres have high protein adsorption capacity, implying that they are promising for applications in biomedical fields such as drug delivery and protein adsorption. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micro-Reaction Chamber Electrodes for Neural Stimulation and Recording

PubMed Central

Shanmugasundaram, Balaji; Gluckman, Bruce J.

2012-01-01

Biocompatible electrodes with smaller geometric area are preferred to improve the selectivity of the neural recording and stimulation applications. We introduce the concept of a micro-reaction chamber (µRC) in which a volume within the electrode back plane is used to confine and sequester the electrochemical reactions used for charge passage. The µRC electrode design helps decrease impedance and improves the charge storage capacity without altering the geometry of the active site. Here we demonstrate that µRC electrodes fabricated from 50 µm diameter microwire have significantly improved charge storage capacity and lowered impedance at physiologically relevant frequencies in phosphate buffered saline solution compared with other designs. PMID:22254394

Cyclodextrin-modified MEKC for enantioseparation of hexaconazole, penconazole, and myclobutanil.

PubMed

Wan Ibrahim, Wan Aini; Hermawan, Dadan; Sanagi, M Marsin; Aboul-Enein, Hassan Y

2009-02-01

A CD-modified micellar EKC (CD-MEKC) method with 2-hydroxypropyl-gamma-CD (HP-gamma-CD) as chiral selector for the enantioseparation of three chiral triazole fungicides, namely hexaconazole, penconazole, and myclobutanil, is reported for the first time. Simultaneous enantioseparation of the three triazole fungicides was successfully achieved using a CD-MEKC system containing 40 mM HP-gamma-CD and 50 mM SDS in 25 mM phosphate buffer (pH 3.0) solution with resolutions (R(s)) greater than 1.60, peak efficiencies (N) greater than 200,000 for all enantiomers and an analysis time within 15 min compared to 36 min as previously reported using sulfated-beta-CD.

Piezoresistive cantilever array sensor for consolidated bioprocess monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Seonghwan Sam; Rahman, Touhidur; Senesac, Larry R

2009-01-01

Cellulolytic microbes occur in diverse natural niches and are being screened for industrial modification and utility. A microbe for Consolidated bioprocessing (CBP) development can rapidly degrade pure cellulose and then ferment the resulting sugars into fuels. To identify and screen for novel microbes for CBP, we have developed a piezoresistive cantilever array sensor which is capable of simultaneous monitoring of glucose and ethanol concentration changes in a phosphate buffer solution. 4-mercaptophenylboronic acid (4-MPBA) and polyethyleneglycol (PEG)-thiol are employed to functionalize each piezoresistive cantilever for glucose and ethanol sensing, respectively. Successful concentration measurements of glucose and ethanol with minimal interferences aremore » obtained with our cantilever array sensor.« less

Development and study the performance of PBA cladding modified fiber optic intrinsic biosensor for urea detection

NASA Astrophysics Data System (ADS)

Botewad, S. N.; Pahurkar, V. G.; Muley, G. G.

2016-05-01

The fabrication and study of a cladding modified fiber optic intrinsic urea biosensor based on evanescent wave absorbance has been presented. The sensor was prepared using cladding modification technique by removing a small portion of cladding of an optical fiber and modifying with an active cladding of porous polyaniline-boric acid (PBA) matrix to immobilize enzyme-urease through cross-linking via glutaraldehyde. The nature of as-synthesized and deposited PBA film on fiber optic sensing element was studied by ultraviolet-visible (UV-vis) spectroscopy and X-ray diffraction (XRD) analysis. The performance of the developed sensor was studied for different urea concentrations in solutions prepared in phosphate buffer.

Fabrication of a magnetic helical mesostructured silica rod

NASA Astrophysics Data System (ADS)

Zhang, Lei; Zhang Qiao, Shi; Cheng, Lina; Yan, Zifeng; Qing Lu, Gao Max

2008-10-01

We report a one-step synthesis of magnetic helical mesostructured silica (MHMS) by self-assembly of an achiral surfactant, magnetic nanocrystals with stearic acid ligands and silicate. This core-shell structured material consists of an Fe3O4 superparamagnetic nanocrystal core and a highly ordered periodic helical mesoporous silica shell. We propose that the formation of the helical structure is induced by the interaction between the surfactant and dissociated stearic acid ligands. The MHMS obtained possesses superparamagnetism, uniform mesostructure, narrow pore size distribution, high surface area, and large pore volume. Furthermore, the drug release process is demonstrated using aspirin as a drug model and MHMS as a drug carrier in a sodium phosphate buffer solution.

Biaxially textured composite substrates

DOEpatents

Groves, James R.; Foltyn, Stephen R.; Arendt, Paul N.

2005-04-26

An article including a substrate, a layer of a metal phosphate material such as an aluminum phosphate material upon the surface of the substrate, and a layer of an oriented cubic oxide material having a rock-salt-like structure upon the metal phosphate material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon a layer of a buffer material such as a SrTi.sub.x Ru.sub.1-x O.sub.3 layer.

Effect of ionic strength and presence of serum on lipoplexes structure monitorized by FRET

PubMed Central

Madeira, Catarina; Loura, Luís MS; Prieto, Manuel; Fedorov, Aleksander; Aires-Barros, M Raquel

2008-01-01

Background Serum and high ionic strength solutions constitute important barriers to cationic lipid-mediated intravenous gene transfer. Preparation or incubation of lipoplexes in these media results in alteration of their biophysical properties, generally leading to a decrease in transfection efficiency. Accurate quantification of these changes is of paramount importance for the success of lipoplex-mediated gene transfer in vivo. Results In this work, a novel time-resolved fluorescence resonance energy transfer (FRET) methodology was used to monitor lipoplex structural changes in the presence of phosphate-buffered saline solution (PBS) and fetal bovine serum. 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/pDNA lipoplexes, prepared in high and low ionic strength solutions, are compared in terms of complexation efficiency. Lipoplexes prepared in PBS show lower complexation efficiencies when compared to lipoplexes prepared in low ionic strength buffer followed by addition of PBS. Moreover, when serum is added to the referred formulation no significant effect on the complexation efficiency was observed. In physiological saline solutions and serum, a multilamellar arrangement of the lipoplexes is maintained, with reduced spacing distances between the FRET probes, relative to those in low ionic strength medium. Conclusion The time-resolved FRET methodology described in this work allowed us to monitor stability and characterize quantitatively the structural changes (variations in interchromophore spacing distances and complexation efficiencies) undergone by DOTAP/DNA complexes in high ionic strength solutions and in presence of serum, as well as to determine the minimum amount of potentially cytotoxic cationic lipid necessary for complete coverage of DNA. This constitutes essential information regarding thoughtful design of future in vivo applications. PMID:18302788

Effect of water content on the glass transition temperature of mixtures of sugars, polymers, and penetrating cryoprotectants in physiological buffer.

PubMed

Drake, Andrew C; Lee, Youngjoo; Burgess, Emma M; Karlsson, Jens O M; Eroglu, Ali; Higgins, Adam Z

2018-01-01

Long-term storage of viable mammalian cells is important for applications ranging from in vitro fertilization to cell therapy. Cryopreservation is currently the most common approach, but storage in liquid nitrogen is relatively costly and the requirement for low temperatures during shipping is inconvenient. Desiccation is an alternative strategy with the potential to enable viable cell preservation at more convenient storage temperatures without the need for liquid nitrogen. To achieve stability during storage in the dried state it is necessary to remove enough water that the remaining matrix forms a non-crystalline glassy solid. Thus, the glass transition temperature is a key parameter for design of cell desiccation procedures. In this study, we have investigated the effects of moisture content on the glass transition temperature (Tg) of mixtures of sugars (trehalose or raffinose), polymers (polyvinylpyrrolidone or Ficoll), penetrating cryoprotectants (ethylene glycol, propylene glycol, or dimethyl sulfoxide), and phosphate buffered saline (PBS) solutes. Aqueous solutions were dried to different moisture contents by equilibration with saturated salt solutions, or by baking at 95°C. The glass transition temperatures of the dehydrated samples were then measured by differential scanning calorimetry. As expected, Tg increased with decreasing moisture content. For example, in a desiccation medium containing 0.1 M trehalose in PBS, Tg ranged from about 360 K for a completely dry sample to about 220 K at a water mass fraction of 0.4. Addition of polymers to the solutions increased Tg, while addition of penetrating cryoprotectants decreased Tg. Our results provide insight into the relationship between relative humidity, moisture content and glass transition temperature for cell desiccation solutions containing sugars, polymers and penetrating cryoprotectants.

Effect of water content on the glass transition temperature of mixtures of sugars, polymers, and penetrating cryoprotectants in physiological buffer

PubMed Central

Burgess, Emma M.; Karlsson, Jens O. M.; Eroglu, Ali

2018-01-01

Long-term storage of viable mammalian cells is important for applications ranging from in vitro fertilization to cell therapy. Cryopreservation is currently the most common approach, but storage in liquid nitrogen is relatively costly and the requirement for low temperatures during shipping is inconvenient. Desiccation is an alternative strategy with the potential to enable viable cell preservation at more convenient storage temperatures without the need for liquid nitrogen. To achieve stability during storage in the dried state it is necessary to remove enough water that the remaining matrix forms a non-crystalline glassy solid. Thus, the glass transition temperature is a key parameter for design of cell desiccation procedures. In this study, we have investigated the effects of moisture content on the glass transition temperature (Tg) of mixtures of sugars (trehalose or raffinose), polymers (polyvinylpyrrolidone or Ficoll), penetrating cryoprotectants (ethylene glycol, propylene glycol, or dimethyl sulfoxide), and phosphate buffered saline (PBS) solutes. Aqueous solutions were dried to different moisture contents by equilibration with saturated salt solutions, or by baking at 95°C. The glass transition temperatures of the dehydrated samples were then measured by differential scanning calorimetry. As expected, Tg increased with decreasing moisture content. For example, in a desiccation medium containing 0.1 M trehalose in PBS, Tg ranged from about 360 K for a completely dry sample to about 220 K at a water mass fraction of 0.4. Addition of polymers to the solutions increased Tg, while addition of penetrating cryoprotectants decreased Tg. Our results provide insight into the relationship between relative humidity, moisture content and glass transition temperature for cell desiccation solutions containing sugars, polymers and penetrating cryoprotectants. PMID:29304068

Influence of Anti-inflammatory Drugs on the Rheological Properties of Synovial Fluid and Its Components

NASA Astrophysics Data System (ADS)

Krause, Wendy E.; Klossner, Rebecca R.; Liang, Jing; Colby, Ralph H.

2006-03-01

The polyelectrolyte hyaluronic acid (HA, hyaluronan), its interactions with anti-inflammatory drugs and other biopolymers, and its role in synovial fluid are being studied. We are investigating the rheological properties of sodium hyaluronate (NaHA) solutions and an experimental model of synovial fluid (comprised of NaHA, and the plasma proteins albumin and γ-globulins). Steady shear measurements on bovine synovial fluid, the synovial fluid model, and plasma protein solutions indicate that the fluids are rheopectic (stress increases with time under steady shear). In addition, the influence of anti-inflammatory agents on these solutions is being explored. Initial results indicate that D-penicillamine and hydroxychloroquine (HCQ) affect the rheology of the synovial fluid model and its components. While HCQ has no effect on the viscosity of NaHA solutions, it inhibits/suppresses the observed rheopexy of the synovial fluid model and plasma protein solutions. In contrast, D-penicillamine has a complex, time dependent effect on the viscosity of NaHA solutions,---reducing the zero shear rate viscosity of a 3 mg/mL NaHA (in phosphate buffered saline) by ca. 40% after 44 days. The potential implications of these results will be discussed.

Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate.

PubMed

Kawasaki, Kosei; Kamagata, Yoichi

2017-11-01

Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H 2 O 2 ) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659-7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H 2 O 2 formation in agar. The H 2 O 2 formation was pH dependent: H 2 O 2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H 2 O 2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H 2 O 2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H 2 O 2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H 2 O 2 from PT medium, these observations indicate that although H 2 O 2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H 2 O 2 levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H 2 O 2 formation from agar. H 2 O 2 formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H 2 O 2 formation. Amendment of catalase or pyruvate, a well-known H 2 O 2 -scavenging agent, effectively eliminated H 2 O 2 Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium. Copyright © 2017 American Society for Microbiology.

Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate

PubMed Central

Kamagata, Yoichi

2017-01-01

ABSTRACT Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H2O2) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659–7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H2O2 formation in agar. The H2O2 formation was pH dependent: H2O2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H2O2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H2O2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H2O2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H2O2 from PT medium, these observations indicate that although H2O2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H2O2 levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H2O2 formation from agar. H2O2 formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H2O2 formation. Amendment of catalase or pyruvate, a well-known H2O2-scavenging agent, effectively eliminated H2O2. Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium. PMID:28821549

Formation of the thioester, N,S-diacetylcysteine, from acetaldehyde and N,N'-diacetylcystine in aqueous solution with ultraviolet light

NASA Technical Reports Server (NTRS)

Weber, A. L.

1981-01-01

The thioester, N,S-diacetylcysteine, is formed during the illumination of phosphate buffered (pH 7.0) aqueous solutions of acetaldehyde and N,N'-diacetylcystine with ultraviolet light. The yield of N,S-diacetylcysteine relative to N-acetylcysteine and unidentified products progressively increases as ultraviolet light below 239 nm, 253 nm and 281 nm is cut off with optical filters. When ultraviolet light below 320 nm is removed with an optical filter, there is no detectable reaction. Illumination of 0.025 M N,N'-diacetylcystine with 0.5 M and 1.0 M acetaldehyde with filtered ultraviolet light gives, respectively, 20% and 80% yields of N,S-diacetylcysteine. In the reaction with 1.0 M acetaldehyde, N-acetylcysteine forms early in the reaction and later decreases with its conversion to N,S-diacetylcysteine. The prebiotic significance of these reactions is discussed.

Self-assembled phytosterol-fructose-chitosan nanoparticles as a carrier of anticancer drug.

PubMed

Qiu, Yeyan; Zhu, Jun; Wang, Jianting; Gong, Renmin; Zheng, Mingming; Huang, Fenghong

2013-08-01

Self-assembled nanoparticles were synthesized from water-soluble fructose-chitosan, substituted by succinyl linkages with phytosterols as hydrophobic moieties for self-assembly. The physicochemical properties of the prepared self-assembled nanoparticles were characterized by Fourier transform infrared spectroscopy, fluorescence spectroscopy, and transmission electron microscopy. Doxorubicin (DOX), as a model anticancer drug, was physically entrapped inside prepared self-assembled nanoparticles by the dialysis method. With increasing initial levels of the drug, the drug loading content increased, but the encapsulation efficiency decreased. The release profiles in vitro demonstrated that the DOX showed slow sustained released over 48 h, and the release rate in phosphate buffered saline (PBS) solution (pH 7.4) was much slower than in PBS solution (pH 5.5 and pH 6.5), indicating the prepared self-assembled nanoparticles had the potential to be used as a carrier for targeted delivery of hydrophobic anticancer drugs with declined cytotoxicity to normal tissues.

Comparative evaluation of the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and xylitol-containing chewing gum on salivary flow rate, pH and buffering capacity in children: An in vivo study.

PubMed

Hegde, Rahul J; Thakkar, Janhavi B

2017-01-01

This study aimed to compare and evaluate the changes in the salivary flow rate, pH, and buffering capacity before and after chewing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and xylitol-containing chewing gums in children. Sixty children aged between 8 and 12 years were selected for the study. They were randomly divided into Group 1 (CPP-ACP chewing gum) and Group 2 (xylitol-containing chewing gum) comprising thirty children each. Unstimulated and stimulated saliva samples at 15 and 30 min interval were collected from all children. All the saliva samples were estimated for salivary flow rate, pH, and buffering capacity. Significant increase in salivary flow rate, pH, and buffering capacity from baseline to immediately after spitting the chewing gum was found in both the study groups. No significant difference was found between the two study groups with respect to salivary flow rate and pH. Intergroup comparison indicated a significant increase in salivary buffer capacity in Group 1 when compared to Group 2. Chewing gums containing CPP-ACP and xylitol can significantly increase the physiochemical properties of saliva. These physiochemical properties of saliva have a definite relation with caries activity in children.

Bactericidal Effects of HVOF-Sprayed Nanostructured TiO2 on Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Jeffery, B.; Peppler, M.; Lima, R. S.; McDonald, A.

2010-01-01

Titanium dioxide (TiO2) has been shown to exhibit photocatalytic bactericidal activity. This preliminary study focused on examining the photocatalytic activity of high-velocity oxy-fuel (HVOF) sprayed nanostructured TiO2 coatings to kill Pseudomonas aeruginosa. The surfaces of the nanostructured TiO2 coatings were lightly polished before addition of the bacterial solution. Plates of P. aeruginosa were grown, and then suspended in a phosphate buffer saline (PBS) solution. The concentration of bacteria used was determined by a photo-spectrometer, which measured the amount of light absorbed by the bacteria-filled solution. This solution was diluted and pipetted onto the coating, which was exposed to white light in 30-min intervals, up to 120 min. It was found that on polished HVOF-sprayed coatings exposed to white light, 24% of the bacteria were killed after exposure for 120 min. On stainless steel controls, approximately 6% of the bacteria were not recovered. These preliminary results show that thermal-sprayed nanostructured TiO2 coatings exhibited photocatalytic bactericidal activity with P. aeruginosa.

High-performance porous polylactide stereocomplex crystallite scaffolds prepared by solution blending and salt leaching.

PubMed

Xie, Yan; Lan, Xiao-Rong; Bao, Rui-Ying; Lei, Yang; Cao, Zhi-Qiang; Yang, Ming-Bo; Yang, Wei; Wang, Yun-Bing

2018-09-01

Biodegradable stereocomplex crystallite polylactide (SC-PLA) porous scaffolds with well-defined pore structures, high heat resistance, mechanical strength, and solvent resistance together with good biocompatibility, were obtained through solution casting of mixed poly(l-lactide) and poly(d-lactide) solution and subsequent leaching of sodium chloride particles. The pore structure of the SC-PLA scaffolds can be perfectly maintained after a high-pressure sterilization treatment at 121 °C, owing to the extensive formation of stereocomplex crystallites in the scaffolds. In vivo pilot study demonstrates that the fibroblasts of rats can infiltrate into the SC-PLA scaffolds well through the open pores. Degradation tests in phosphate-buffered saline solution reveal that the structure of SC-PLA scaffolds was quite stable due to the enhanced hydrolysis-resistance and improved mechanical properties of the scaffolds. These results reveal that SC-PLA scaffolds with good biocompatibility are potentially to be used as implanted biomaterials for the regeneration and restoration of tissues or organs. Copyright © 2018 Elsevier B.V. All rights reserved.

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

PubMed Central

Cudd, A; Bhogal, M; O'Mullane, J; Goddard, P

1991-01-01

When dissolved in N,N-dimethylformamide and then dialyzed against phosphate-buffered saline, A-B-A block copolymers composed of poly [N5-(2-hydroxyethyl)-L-glutamine]-block-poly(gamma-benzyl-L-glutamate)- block-poly [N5-(2-hydroxyethyl)-L-glutamine] form particles. The particles are cage-like structures with average diameters of 300 nm (average polydispersity, 0.3-0.5). They are stable in aqueous solution at 4 degrees C for up to 3 weeks, at which time flocculation becomes apparent. Negative staining and freeze-fracture electron microscopy suggest that cage-like particles are formed by selective association of segregated micelle populations. A model of particle formation is presented in which B blocks form micelles in dimethylformamide. On dialysis against an aqueous solution, the extended A blocks then associate intermolecularly to form rod-shaped micelles, which connect the B block micelles. The result is a meshed cage-like particle. The implications of these observations on the aggregation behavior of polymeric surfactants in dilute solution are discussed. Images PMID:11607245

Bio-corrosion and cytotoxicity studies on novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses

DOE PAGES

Vincent, S.; Daiwile, A.; Devi, S. S.; ...

2014-09-26

Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr 55Co 30Ti 15 and Cu 60Zr 20Ti 20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experimentsmore » was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. As a result, the comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.« less

HUMAN PANCREATIC POLYPEPTIDE IN A PHOSPHOLIPID BASED MICELLAR FORMULATION

PubMed Central

Banerjee, Amrita; Onyuksel, Hayat

2012-01-01

Purpose Pancreatic polypeptide (PP) has important glucoregulatory functions and thereby holds significance in the treatment of diabetes and obesity. However, short plasma half-life and aggregation propensity of PP in aqueous solution, limits its therapeutic application. To address these issues, we prepared and characterized a formulation of PP in sterically stabilized micelles (SSM) that protects and stabilizes PP in its active conformation. Methods PP-SSM was prepared by incubating PP with SSM dispersion in buffer. Peptide-micelle association and freeze-drying efficacy of the formulation was characterized in phosphate buffers with or without sodium chloride using dynamic light scattering, fluorescence spectroscopy and circular dichroism. The degradation kinetics of PP-SSM in presence of proteolytic enzyme was determined using HPLC and bioactivity of the formulation was evaluated by in vitro cAMP inhibition. Results PP self-associated with SSM and this interaction was influenced by presence/absence of sodium chloride in the buffer. The formulation was effectively lyophilized, demonstrating feasibility for its long-term storage. The stability of peptide against proteolytic degradation was significantly improved and PP in SSM retained its bioactivity in vitro. Conclusions Self-association of PP with phospholipid micelles addressed the delivery issues of the peptide. This PP nanomedicine should be further developed for the treatment of diabetes. PMID:22399387

DOE Office of Scientific and Technical Information (OSTI.GOV)

Streltsov, Victor A.; Titmuss, Stephen J.; Epa, V. Chandana

Neurodegeneration observed in Alzheimer disease (AD) is believed to be related to the toxicity from reactive oxygen species (ROS) produced in the brain by the amyloid-{beta} (A{beta}) protein bound primarily to copper ions. The evidence for an oxidative stress role of A{beta}-Cu redox chemistry is still incomplete. Details of the copper binding site in A{beta} may be critical to the etiology of AD. Here we present the structure determined by combining x-ray absorption spectroscopy (XAS) and density functional theory analysis of A{beta} peptides complexed with Cu{sup 2+} in solution under a range of buffer conditions. Phosphate-buffered saline buffer salt (NaCl)more » concentration does not affect the high-affinity copper binding mode but alters the second coordination sphere. The XAS spectra for truncated and full-length A{beta}-Cu{sup 2+} peptides are similar. The novel distorted six-coordinated (3N3O) geometry around copper in the A{beta}-Cu{sup 2+} complexes include three histidines: glutamic, or/and aspartic acid, and axial water. The structure of the high-affinity Cu{sup 2+} binding site is consistent with the hypothesis that the redox activity of the metal ion bound to A{beta} can lead to the formation of dityrosine-linked dimers found in AD.« less

Ultra-high-performance liquid chromatography-tandem mass spectrometry measurement of climbazole deposition from hair care products onto artificial skin and human scalp.

PubMed

Chen, Guoqiang; Hoptroff, Michael; Fei, Xiaoqing; Su, Ya; Janssen, Hans-Gerd

2013-11-22

A sensitive and specific ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the measurement of climbazole deposition from hair care products onto artificial skin and human scalp. Deuterated climbazole was used as the internal standard. Atmospheric pressure chemical ionization (APCI) in positive mode was applied for the detection of climbazole. For quantification, multiple reaction monitoring (MRM) transition 293.0>69.0 was monitored for climbazole, and MRM transition 296.0>225.1 for the deuterated climbazole. The linear range ran from 4 to 2000 ng mL(-1). The limit of detection (LOD) and the limit of quantification (LOQ) were 1 ng mL(-1) and 4 ng mL(-1), respectively, which enabled quantification of climbazole on artificial skin and human scalp at ppb level (corresponding to 16 ng cm(-2)). For the sampling of climbazole from human scalp the buffer scrub method using a surfactant-modified phosphate buffered saline (PBS) solution was selected based on a performance comparison of tape stripping, the buffer scrub method and solvent extraction in in vitro studies. Using this method, climbazole deposition in in vitro and in vivo studies was successfully quantified. Copyright © 2013 Elsevier B.V. All rights reserved.

The effect of EDTA, cations, and various buffers on the morphology of erythrocyte membranes: an electron-microscopic study.

PubMed

Pinteric, L; Manery, J F; Chaudry, I H; Madapallimattam, G

1975-05-01

Membranes of human erythrocytes were prepared by stepwise osmotic hemolysis in Ca2+-free solutions. Examination with the electron microscope after negative staining showed some short, conelike protuberances on the surface of about 20 percent of the ghosts, while 80 percent were round, intact spheres. After Ca2+ treatment, all membranes were round and intact. After exposure to ethylenediaminetetraacetic acid (EDTA) (1.0 mM, pH 7.4), the entire ghost surface was covered with long, thin extrusions called stromalytic forms (about 460 per cell). Their sizes, shapes, and fine structure are described. Exposure to ionic calcium (1.4 times 10-minus 4M) abolished the EDTA-induced stromalytic forms. A second exposure to EDTA reversed this Ca2+ effect. ATP, like EDTA, produced stromalytic forms. EDTA-induced stromalytic forms were also abolished by Zn2+, La3+, and Nd3+ at concentrations of 1-5 times 10-minus 4 M. Mg2+ at 10-minus 2 M was ineffective. Ghosts were prepared by graded lysis in various buffers. Those prepared in phosphate were the most stable and provided consistent EDTA effects and Ca2+ reversal. Ghosts in Tris-HCl showed breakdown unless salt was added. Moderately satisfactory ghosts were also obtained in Hepes-NaOH buffer and salt.

Tyrosine quenching of tryptophan phosphorescence in glyceraldehyde-3-phosphate dehydrogenase from Bacillus stearothermophilus.

PubMed Central

Strambini, G B; Gabellieri, E; Gonnelli, M; Rahuel-Clermont, S; Branlant, G

1998-01-01

Tyrosine is known to quench the phosphorescence of free tryptophan derivatives in solution, but the interaction between tryptophan residues in proteins and neighboring tyrosine side chains has not yet been demonstrated. This report examines the potential role of Y283 in quenching the phosphorescence emission of W310 of glyceraldehyde-3-phosphate dehydrogenase from Bacillus stearothermophilus by comparing the phosphorescence characteristics of the wild-type enzyme to that of appositely designed mutants in which either the second tryptophan residue, W84, is replaced with phenylalanine or Y283 is replaced by valine. Phosphorescence spectra and lifetimes in polyol/buffer low-temperature glasses demonstrate that W310, in both wild-type and W84F (Trp84-->Phe) mutant proteins, is already quenched in viscous low-temperature solutions, before the onset of major structural fluctuations in the macromolecule, an anomalous quenching that is abolished with the mutation Y283V (Tyr283-->Val). In buffer at ambient temperature, the effect of replacing Y283 with valine on the phosphorescence of W310 is to lengthen its lifetime from 50 micros to 2.5 ms, a 50-fold enhancement that again emphasizes how W310 emission is dominated by the local interaction with Y283. Tyr quenching of W310 exhibits a strong temperature dependence, with a rate constant kq = 0.1 s(-1) at 140 K and 2 x 10(4) s(-1) at 293 K. Comparison between thermal quenching profiles of the W84F mutant in solution and in the dry state, where protein flexibility is drastically reduced, shows that the activation energy of the quenching reaction is rather small, Ea < or = 0.17 kcal mol(-1), and that, on the contrary, structural fluctuations play an important role on the effectiveness of Tyr quenching. Various putative quenching mechanisms are examined, and the conclusion, based on the present results as well as on the phosphorescence characteristics of other protein systems, is that Tyr quenching occurs through the formation of an excited-state triplet exciplex. PMID:9635769

The Preparation of Capsaicin-Chitosan Microspheres (CCMS) Enteric Coated Tablets

PubMed Central

Chen, Jian; Huang, Gui-Dong; Tan, Si-Rong; Guo, Jiao; Su, Zheng-Quan

2013-01-01

This study aimed to research the preparation and content determination of capsaicin-chitosan microspheres (CCMS) enteric coated tablets. The core tablets were prepared with the method of wet granulation. Nine formulae were designed to determine the optimal formula of the core tablet. Eudragit L100 was used to prepare the CCMS enteric-coated tablets. The effect of enteric coated formulation variables such as content of talc (10%, 25% and 40%), plasticisers (TEC and DBS), dosage of plasticiser (10%, 20% and 30%) and coating weight (2%, 3% and 5%) were evaluated for drug release characteristics. The in vitro release was studied using 0.1 N HCl and pH 6.8 phosphate buffer. Enteric coated tablets without ruptures or swelling behaviour over 2 h in 0.1 N HCl indicated that these tablets showed acid resistance. The accumulated release rate in phosphate buffer (pH 6.8) revealed that the prepared tablets were able to sustain drug release into the intestine and a first-order release was obtained for capsaicin. This research is the first report of the preparation and content determination of CCMS enteric coated tablets. The sustained release behavior of enteric coated formulations in pH 6.8 phosphate buffer demonstrated that it would be a potential drug delivery platform for sustained delivery of gastric irritant drugs. PMID:24351818

Simple and sensitive determination of five quinolones in food by liquid chromatography with fluorescence detection.

PubMed

Ramos, Macarena; Aranda, Angela; Garcia, Elena; Reuvers, Thea; Hooghuis, Henny

2003-06-15

A simple and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the determination of five different quinolones: enrofloxacin, ciprofloxacin, sarafloxacin, oxolinic acid and flumequine in pork and salmon muscle. The method includes one extraction and clean-up step for the five quinolones together which are detected in two separated HPLC runs by means of their fluorescence. The proposed analytical method involves homogenizing of the tissue sample with 0.05 M phosphate buffer, pH 7.4 and clean-up by Discovery DS-18 cartridges. For chromatographic separation a Symmetry C(18) column is used in two different runs: (1) ciprofloxacin, enrofloxacin and sarafloxacin with acetonitrile-0.02 M phosphate buffer pH 3.0 (18:82) as mobile phase and the detector at excitation wavelength: 280 nm and emission wavelength 450 nm; and (2) oxolinic acid and flumequine with acetonitrile-0.02 M phosphate buffer pH 3.0 (34:66) as mobile phase and excitation wavelength: 312 nm and emission wavelength: 366 nm. Detection limit was as low as 5 ng g(-1), except for sarafloxacin which had a limit of 10 ng g(-1). Standard curves using blank muscle tissues spiked at different levels showed a good linear correlation coefficient, r(2) higher than 0.999 for all quinolones.

Cooperativity between various types of polar solute-solvent interactions in aqueous media.

PubMed

Madeira, Pedro P; Bessa, Ana; Loureiro, Joana A; Álvares-Ribeiro, Luís; Rodrigues, Alírio E; Zaslavsky, Boris Y

2015-08-21

Partition coefficients of seven low molecular weight compounds were measured in multiple aqueous two-phase systems (ATPSs) formed by pairs of different polymers. The ionic composition of each ATPS was varied to include 0.01M sodium phosphate buffer (NaPB), pH 7.4 and 0.1M Na2SO4, 0.15M NaCl, and 0.15M NaClO4 all in 0.01M NaPB, pH 7.4. The differences between the solvent features of the coexisting phases in all the ATPSs were estimated from partitioning of a homologous series of dinitrophenylated-amino acids and by the solvatochromic method. The solute-specific coefficients for the compounds examined were determined by the multiple linear regression analysis using the modified linear solvation energy relationship equation. It is established that the solute specific coefficients characterizing different types of the solute-water interactions (dipole-dipole, dipole-ion, and H-bonding) for a given solute change in the presence of different salt additives in the solute specific manner. It is also found that these characteristics are linearly interrelated. It is suggested that there is a cooperativity between various types of solute-water interactions governed by the solute structure. Copyright © 2015 Elsevier B.V. All rights reserved.

Tannate complexes of antihistaminic drug: sustained release and taste masking approaches.

PubMed

Rahman, Ziyaur; Zidan, Ahmed S; Berendt, Robert T; Khan, Mansoor A

2012-01-17

The aim of this investigation was to evaluate the complexation potential of brompheniramine maleate (BPM) and tannic acid (TA) for sustained release and taste masking effects. The complexes (1:1-1:7 TA to BPM ratio) were prepared by the solvent evaporation method using methanol, phosphate buffer pH 6.8 or 0.1N HCl as common solvents. The complexes were characterized microscopically by scanning electron microscopy (SEM), chemically by Fourier transform infrared (FTIR) and solid-state NMR (SSNMR), thermally by differential scanning calorimetry (DSC), for crystallinity by powder X-ray powder diffraction (PXRD), for organoleptic evaluation by electronic tongue (e-tongue), and for solubility in 0.1N HCl and phosphate buffer pH 6.8. The dissolution studies were carried out using the USP II method at 50 rpm in 500 ml of dissolution media (0.1N HCl or phosphate buffer pH 6.8). SEM images revealed that the morphology of complexes were completely different from the individual components, and all complexes had the same morphological characteristics, irrespective of the solvent used for their preparation, pH or ratio of BPM and TA. The FTIR spectra showed the presence of chemical interactions between the TA and BPM. DSC, PXRD and SSNMR indicated that the drug lost its crystalline nature by formation of the complex. Complexation has significantly reduced the solubility of BPM and sustained the drug release up to 24h in phosphate buffer pH 6.8 media. The bitter taste of the BPM was completely masked which was indicated by Euclidean distance values which was far from the drug but near to its placebo in the complexes in all ratios studied. The taste masked complexes can be potentially developed as suitable dosage forms for pediatric use. In summary, complexation of BPM and TA effectively sustained the dissolution and masked the bitter taste of drug for the development of suitable dosage forms for pediatric use. Published by Elsevier B.V.

Fluoride-containing nanoporous calcium-silicate MTA cements for endodontics and oral surgery: early fluorapatite formation in a phosphate-containing solution.

PubMed

Gandolfi, M G; Taddei, P; Siboni, F; Modena, E; Ginebra, M P; Prati, C

2011-10-01

To test the chemical-physical properties and apatite-forming ability of experimental fluoride-doped calcium silicate cements designed to create novel bioactive materials for use in endodontics and oral surgery. A thermally treated calcium silicate cement (wTC) containing CaCl(2) 5%wt was modified by adding NaF 1%wt (FTC) or 10%wt (F10TC). Cements were analysed by environmental scanning electron microscopy with energy-dispersive X-ray analysis, IR and micro-Raman spectroscopy in wet conditions immediately after preparation or after ageing in a phosphate-containing solution (Dulbecco's phosphate-buffered saline). Calcium and fluoride release and pH of the storage solution were measured. The results obtained were analysed statistically (Tukey's HSD test and two-way anova). The formation of calcium phosphate precipitates (spherulites) was observed on the surface of 24 h-aged cements and the formation of a thick bone-like B-type carbonated apatite layer (biocoating) on 28 day-aged cements. The rate of apatite formation was FTC>F10TC>wTC. Fluorapatite was detected on FTC and F10TC after 1 day of ageing, with a higher fluoride content on F10TC. All the cements released calcium ions. At 5 and 24 h, the wTC had the significantly highest calcium release (P<0.001) that decreased significantly over the storage time. At 3-28 days, FTC and F10TC had significantly higher calcium release than wTC (P<0.05). The F10TC had the significantly highest fluoride release at all times (P<0.01) that decreased significantly over storage time. No significant differences were observed between FTC and wTC. All the cements had a strong alkalinizing activity (OH(-) release) that remained after 28 days of storage. The addition of sodium fluoride accelerated apatite formation on calcium silicate cements. Fluoride-doped calcium silicate cements had higher bioactivity and earlier formation of fluorapatite. Sodium fluoride may be introduced in the formulation of mineral trioxide aggregate cements to enhance their biological behaviour. F-doped calcium silicate cements are promising bone cements for clinical endodontic use. © 2011 International Endodontic Journal.

Biodegradation of carbon nanohorns in macrophage cells

NASA Astrophysics Data System (ADS)

Zhang, Minfang; Yang, Mei; Bussy, Cyrill; Iijima, Sumio; Kostarelos, Kostas; Yudasaka, Masako

2015-02-01

With the rapid developments in the medical applications of carbon nanomaterials such as carbon nanohorns (CNHs), carbon nanotubes, and graphene based nanomaterials, understanding the long-term fate, health impact, excretion, and degradation of these materials has become crucial. Herein, the in vitro biodegradation of CNHs was determined using a non-cellular enzymatic oxidation method and two types of macrophage cell lines. Approximately 60% of the CNHs was degraded within 24 h in a phosphate buffer solution containing myeloperoxidase. Furthermore, approximately 30% of the CNHs was degraded by both RAW 264.7 and THP-1 macrophage cells within 9 days. Inflammation markers such as pro-inflammatory cytokines interleukin 6 and tumor necrosis factor α were not induced by exposure to CNHs. However, reactive oxygen species were generated by the macrophage cells after uptake of CNHs, suggesting that these species were actively involved in the degradation of the nanomaterials rather than in an inflammatory pathway induction.With the rapid developments in the medical applications of carbon nanomaterials such as carbon nanohorns (CNHs), carbon nanotubes, and graphene based nanomaterials, understanding the long-term fate, health impact, excretion, and degradation of these materials has become crucial. Herein, the in vitro biodegradation of CNHs was determined using a non-cellular enzymatic oxidation method and two types of macrophage cell lines. Approximately 60% of the CNHs was degraded within 24 h in a phosphate buffer solution containing myeloperoxidase. Furthermore, approximately 30% of the CNHs was degraded by both RAW 264.7 and THP-1 macrophage cells within 9 days. Inflammation markers such as pro-inflammatory cytokines interleukin 6 and tumor necrosis factor α were not induced by exposure to CNHs. However, reactive oxygen species were generated by the macrophage cells after uptake of CNHs, suggesting that these species were actively involved in the degradation of the nanomaterials rather than in an inflammatory pathway induction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06175f

Structure of Ceramide-1-Phosphate at the Air-Water Solution Interface in the Absence and Presence of Ca2+

PubMed Central

Kooijman, Edgar E.; Vaknin, David; Bu, Wei; Joshi, Leela; Kang, Shin-Woong; Gericke, Arne; Mann, Elizabeth K.; Kumar, Satyendra

2009-01-01

Ceramide-1-phosphate, the phosphorylated form of ceramide, gained attention recently due to its diverse intracellular roles, in particular in inflammation mediated by cPLA2α. However, surprisingly little is known about the physical chemical properties of this lipid and its potential impact on physiological function. For example, the presence of Ca2+ is indispensable for the interaction of Cer-1-P with the C2 domain of cPLA2α. We report on the structure and morphology of Cer-1-P in monomolecular layers at the air/water solution interface in the absence and presence of Ca2+ using diverse biophysical techniques, including synchrotron x-ray reflectivity and grazing angle diffraction, to gain insight into the role and function of Cer-1-P in biomembranes. We show that relatively small changes in pH and the presence of monovalent cations dramatically affect the behavior of Cer-1-P. On pure water Cer-1-P forms a solid monolayer despite the negative charge of the phosphomonoester headgroup. In contrast, pH 7.2 buffer yields a considerably less solid-like monolayer, indicating that charge-charge repulsion becomes important at higher pH. Calcium was found to bind strongly to the headgroup of Cer-1-P even in the presence of a 100-fold larger Na+ concentration. Analysis of the x-ray reflectivity data allowed us to estimate how much Ca2+ is bound to the headgroup, ∼0.5 Ca2+ and ∼1.0 Ca2+ ions per Cer-1-P molecule for the water and buffer subphase respectively. These results can be qualitatively understood based on the molecular structure of Cer-1-P and the electrostatic/hydrogen-bond interactions of its phosphomonoester headgroup. Biological implications of our results are also discussed. PMID:19289047

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reilly, Sean Douglas; Smith, Paul Herrick; Jarvinen, Gordon D.

Understanding the water solubility of plutonium and uranium compounds and residues at TA-55 is necessary to provide a technical basis for appropriate criticality safety, safety basis and accountability controls. Individual compound solubility was determined using published solubility data and solution thermodynamic modeling. Residue solubility was estimated using a combination of published technical reports and process knowledge of constituent compounds. The scope of materials considered includes all compounds and residues at TA-55 as of March 2016 that contain Pu-239 or U-235 where any single item in the facility has more than 500 g of nuclear material. This analysis indicates that themore » following materials are not appreciably soluble in water: plutonium dioxide (IDC=C21), plutonium phosphate (IDC=C66), plutonium tetrafluoride (IDC=C80), plutonium filter residue (IDC=R26), plutonium hydroxide precipitate (IDC=R41), plutonium DOR salt (IDC=R42), plutonium incinerator ash (IDC=R47), uranium carbide (IDC=C13), uranium dioxide (IDC=C21), U 3O 8 (IDC=C88), and uranium filter residue (IDC=R26). This analysis also indicates that the following materials are soluble in water: plutonium chloride (IDC=C19) and uranium nitrate (IDC=C52). Equilibrium calculations suggest that PuOCl is water soluble under certain conditions, but some plutonium processing reports indicate that it is insoluble when present in electrorefining residues (R65). Plutonium molten salt extraction residues (IDC=R83) contain significant quantities of PuCl 3, and are expected to be soluble in water. The solubility of the following plutonium residues is indeterminate due to conflicting reports, insufficient process knowledge or process-dependent composition: calcium salt (IDC=R09), electrorefining salt (IDC=R65), salt (IDC=R71), silica (IDC=R73) and sweepings/screenings (IDC=R78). Solution thermodynamic modeling also indicates that fire suppression water buffered with a commercially-available phosphate buffer would significantly reduce the solubility of PuCl 3 by the precipitation of PuPO 4.« less

Studies on the effect of virtual crosslinking on the hydrolytic stability of novel aliphatic polyurethane ureas for blood contact applications.

PubMed

Thomas, V; Jayabalan, M

2001-07-01

The effect of virtual crosslinking on the hydrolytic stability of completely aliphatic novel poly(urethane ureas), HFL9-PU1 (hard-segment content 57.5%) and HFL13-PU2 (hard-segment content 67.9%) based on 4,4'-methylene bis(cyclohexyl isocyanate) (H(12)MDI)-hydroxy-terminated polybutadiene-1,6-hexamethylene diamine, was studied. Fourier transform infrared-attenuated total reflectance and wide-angle X-ray diffraction studies revealed hydrogen-bonding interaction and microphase separation and formation of crystallites by short- and long-range ordering in hard-segment domains. Three-dimensional networks from hydrogen bonding in the present polymers lead to virtually crosslinking and insolubility. These polymers were noncytotoxic to L929 fibroblast cells. The hemolytic potential is below the accepted limit. The studies on in vitro biostability in Ringer's solution, phosphate buffered saline, and papain enzyme revealed no weight loss. The infrared spectral studies revealed changes in the surface, especially on HFL9-PU1 aged in Ringer's solution and phosphate buffered saline, and no changes when aged in papain. The marginal changes noticed in tensile properties were attributed to the changes in degree of hydrogen bonding and associated rearrangement of molecular structure in the bulk. The results revealed that the lesser the crosslinking in virgin polymer, the higher the crosslinking in aged polymer and vice versa. Increased crosslinking during aging provided increased tensile properties in the aged polymer over the virgin polymer and vice versa. For comparison, an aliphatic polyetherurethane urea (HFL16-PU3) was also synthesized using poly(oxy tetra methylene glycol) in addition to the above reactants. Though both HFL9-PU1 and HFL16-PU3 contained the same hard-segment content, the aged sample of the latter showed decreased tensile properties with increased crosslinking during aging in contrast to the former. This was attributed to less microphase separation in the virgin HFL16-PU3 polymer.

The use of stable isotopes for Cr(VI) determination in silty-clay soil solution.

PubMed

Zuliani, Tea; Sčančar, Janez; Milačič, Radmila

2013-09-01

In assessing the environmental hazard of Cr(VI) present in soil, exchangeable Cr(VI) is important, since it can be easily washed out from the upper part of the soil into subsurface soil, surface and ground water, and taken up by plants. The aim of this study was to evaluate the degree of species interconversion that may occur during the extraction of exchangeable Cr(VI) from silty-clay soil with phosphate buffer in order to establish an extraction method that would be effective, accurate and with minimal or no species interconversions. The Cr(VI) concentration in soil extracts was determined by speciated isotope dilution inductively coupled plasma mass spectrometry (SID-ICP-MS). The study was performed on soil samples from a field treated with tannery waste for 17 years. Samples were spiked by enriched stable isotopic solutions of (50)Cr(VI) and (53)Cr(III) that were added to phosphate buffers (0.1 M KH2PO4-K2HPO4 (pH 7.2) and/or 0.1 M K2HPO4 (pH 8)). To optimize extraction, mechanical shaking and/or ultrasound-assisted extraction were compared. The separation and detection of Cr species was performed by high-performance liquid chromatography (HPLC) ICP-MS. When mechanical shaking was applied, 90 % reduction of Cr(VI) was induced by extraction with 0.1 M KH2PO4-K2HPO4, while with 0.1 M K2HPO4 reduction was around 40 %. To shorten the extraction time and the possibility of species interconversions, ultrasound-assisted extraction was further applied only with 0.1 M K2HPO4. For total extraction of exchangeable Cr(VI) with a maximum 10 % reduction of Cr(VI), five consecutive ultrasound-assisted extractions were needed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundaramurthi, Prakash; Suryanarayanan, Raj

To effectively inhibit succinate buffer crystallization and the consequent pH changes in frozen solutions. Using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), the crystallization behavior of succinate buffer in the presence of either (i) a crystallizing (glycine, mannitol, trehalose) or (ii) a non-crystallizing cosolute (sucrose) was evaluated. Aqueous succinate buffer solutions, 50 or 200 mM, at pH values 4.0 or 6.0 were cooled from room temperature to -25 C at 0.5 C/min. The pH of the solution was measured as a function of temperature using a probe designed to function at low temperatures. The final lyophiles prepared from thesemore » solutions were characterized using synchrotron radiation. When the succinic acid solution buffered to pH 4.0, in the absence of a cosolute, was cooled, there was a pronounced shift in the freeze-concentrate pH. Glycine and mannitol, which have a tendency to crystallize in frozen solutions, remained amorphous when the initial pH was 6.0. Under this condition, they also inhibited buffer crystallization and prevented pH change. At pH 4.0 (50 mM initial concentration), glycine and mannitol crystallized and did not prevent pH change in frozen solutions. While sucrose, a non-crystallizing cosolute, did not completely prevent buffer crystallization, the extent of crystallization was reduced. Sucrose decomposition, based on XRD peaks attributable to {beta}-D-glucose, was observed in frozen buffer solutions with an initial pH of 4.0. Trehalose completely inhibited crystallization of the buffer components when the initial pH was 6.0 but not at pH 4.0. At the lower pH, the crystallization of both trehalose dihydrate and buffer components was evident. When retained amorphous, sucrose and trehalose effectively inhibited succinate buffer component crystallization and the consequent pH shift. However, when trehalose crystallized or sucrose degraded to yield a crystalline decomposition product, crystallization of buffer was observed. Similarly, glycine and mannitol, two widely used bulking agents, inhibited buffer component crystallization only when retained amorphous. In addition to stabilizing the active pharmaceutical ingredient, lyoprotectants may prevent solution pH shift by inhibiting buffer crystallization.« less

Kinetics and mechanism of bacterial inactivation by ultrasound waves and sonoprotective effect of milk components.

PubMed

Gera, N; Doores, S

2011-03-01

Inactivation of Escherichia coli and Listeria monocytogenes were investigated in buffer and milk upon treatment with ultrasound waves (USW). In addition, sonoprotective effect of milk components and ultrasound-induced changes in bacterial cells were investigated using scanning electron microscopy (SEM). Bacterial cells were added to phosphate buffer, whole milk, skim milk, or simulated milk ultrafiltrate (SMUF). To determine the sonoprotective effect of milk components, lactose (5%), casein (3%), or β lactoglobulin (0.3%) was added to SMUF. Samples were sonicated with 24 kHz pulse USW while maintaining the system temperature between 30 to 35 °C. Aliquots were drawn at set times during sonication and bacteria were enumerated by surface plating appropriate dilutions on selective and nonselective media plates. Escherichia coli exhibited significantly higher D values in whole (2.43 min) and skim milk (2.41 min) than phosphate buffer (2.19 min). Listeria monocytogenes also showed higher D values in whole (9.31 min) and skim milk (8.61 min) compared to phosphate buffer (7.63 min). Data suggest that milk exerts a sonoprotective effect on these bacteria. Escherichia coli exhibited a log-linear inactivation kinetics followed by tailing whereas L. monocytogenes showed 1st-order kinetics throughout. Among the milk components tested, presence of lactose in SMUF resulted in significantly higher D values than SMUF for both organisms suggesting that lactose was exerting a protective effect on bacteria. SEM images showed that USW caused mechanical damage to the cell wall and cell membrane of bacteria leading to their inactivation.

Influence of diluent and sample processing methods on the recovery of the biocontrol agent Pantoea agglomerans CPA-2 from different fruit surfaces.

PubMed

Torres, R; Viñas, I; Usall, J; Remón, D; Teixidó, N

2012-08-01

Determining the populations of biocontrol agents applied as a postharvest treatment on fruit surfaces is fundamental to the assessment of the microorganisms' ability to colonise and persist on fruit. To obtain maximum recovery, we must develop a methodology that involves both diluent and processing methods and that does not affect the viability of the microorganisms. The effect of diluent composition was evaluated using three diluents: phosphate buffer, peptone saline and buffered peptone saline. An additional study was performed to compare three processing methods (shaking plus sonication, stomaching and shaking plus centrifugation) on the recovery efficiency of Pantoea agglomerans strain CPA-2 from apples, oranges, nectarines and peaches treated with this biocontrol agent. Overall, slight differences occurred among diluents, although the phosphate buffer maintained the most ideal pH for CPA-2 growth (between 5.2 and 6.2). Stomaching, using the phosphate buffer as diluent, was the best procedure for recovering and enumerating the biocontrol agent; this fact suggested that no lethal effects from naturally occurring antimicrobial compounds present on the fruit skins and/or produced when the tissues were disrupted affected the recovery of the CPA-2 cells, regardless of fruit type. The growth pattern of CPA-2 on fruits maintained at 20°C and under cold conditions was similar to that obtained in previous studies, which confirms the excellent adaptation of this strain to conditions commonly used for fruit storage. Copyright © 2012 Elsevier B.V. All rights reserved.

Cytotoxic and inflammatory effects of contact lens solutions on human corneal epithelial cells in vitro.

PubMed

Oh, Sarah; McCanna, David J; Subbaraman, Lakshman N; Jones, Lyndon W

2018-06-01

To ascertain the effect that four contact lens (CL) multipurpose solutions (MPS) have on the viability and release of pro-inflammatory cytokines from human corneal epithelial cells (HCEC). HCEC were exposed to four different MPS at various concentrations for 18 hours. The cells were also exposed to phosphate buffer, borate buffer, and PHMB. The cell viability was evaluated using the alamarBlue assay. The release of pro-inflammatory cytokines was measured using a Multiplex electrochemiluminescent assay. MPS-A, MPS-B and MPS-C all reduced cell metabolic activity p < 0.05 from control with MPS-A showing the greatest cytotoxic effect (maximum reduction, 90.6%). In contrast, MPS-D showed no significant reductions in cytotoxicity except at the highest concentration tested (19% reduction at 20% MPS concentration). Of the four cytokines evaluated MPS-C showed a substantial increase in the release of IL-1β, IL-6, IL-8, and TNF-α at higher concentrations when compared to control p < 0.05. At the 20% concentration of MPS-A and MPS-B the release of IL-1 β increased p < 0.05 but the release of IL-6, IL-8, and TNF-α decreased. MPS-D did not cause a change in the release of cytokines IL-1β, IL-6, IL-8 and TNF-α p > 0.05. Exposing the cells to borate buffer and PHMB caused an increase in the release of TNF-α p < 0.05. This investigation demonstrates that at different concentration levels, several of the MPS tested showed a decrease in viability and an increase in the release of inflammatory cytokines from HCEC. The borate buffer component as well as PHMB appears to contribute to this pro-inflammatory reaction. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Poly(amidoamine) dendrimers as ophthalmic vehicles for ocular delivery of pilocarpine nitrate and tropicamide.

PubMed

Vandamme, Th F; Brobeck, L

2005-01-20

The purpose of this study was to determine the influence of a controlled incremental increase in size, molecular weight and number of amine, carboxylate and hydroxyl surface groups in several series of poly(amidoamine) (PAMAM) dendrimers for controlled ocular drug delivery. The duration of residence time was evaluated after solubilization of several series of PAMAM dendrimers (generations 1.5 and 2-3.5 and 4) in buffered phosphate solutions containing 2 per thousand (w/v) of fluorescein. The New Zealand albino rabbit was used as an in vivo model for qualitative and quantitative assessment of ocular tolerance and retention time after a single application of 25 microl of dendrimer solution to the eye. The same model was also used to determine the prolonged miotic or mydriatic activities of dendrimer solutions, some containing pilocarpine nitrate and some tropicamide, respectively. Residence time was longer for the solutions containing dendrimers with carboxylic and hydroxyl surface groups. No prolongation of remanence time was observed when dendrimer concentration (0.25-2%) increased. The remanence time of PAMAM dendrimer solutions on the cornea showed size and molecular weight dependency. This study allowed novel macromolecular carriers to be designed with prolonged drug residence time for the ophthalmic route.

Design of Phosphonium-Type Zwitterion as an Additive to Improve Saturated Water Content of Phase-Separated Ionic Liquid from Aqueous Phase toward Reversible Extraction of Proteins

PubMed Central

Ito, Yoritsugu; Kohno, Yuki; Nakamura, Nobuhumi; Ohno, Hiroyuki

2013-01-01

We designed phosphonium-type zwitterion (ZI) to control the saturated water content of separated ionic liquid (IL) phase in the hydrophobic IL/water biphasic systems. The saturated water content of separated IL phase, 1-butyl-3-methyimidazolium bis(trifluoromethanesulfonyl)imide, was considerably improved from 0.4 wt% to 62.8 wt% by adding N,N,N-tripentyl-4-sulfonyl-1-butanephosphonium-type ZI (P555C4S). In addition, the maximum water content decreased from 62.8 wt% to 34.1 wt% by increasing KH2PO4/K2HPO4 salt content in upper aqueous phosphate buffer phase. Horse heart cytochrome c (cyt.c) was dissolved selectively in IL phase by improving the water content of IL phase, and spectroscopic analysis revealed that the dissolved cyt.c retained its higher ordered structure. Furthermore, cyt. c dissolved in IL phase was re-extracted again from IL phase to aqueous phase by increasing the concentration of inorganic salts of the buffer solution. PMID:24013379

First derivative spectrophotometric and LC determination of benoxinate hydrochloride and its degradation products.

PubMed

El-Gindy, A

2000-03-01

Two methods are presented for the determination of benoxinate HCI and its acid and alkali-induced degradation products using first derivative (1D) spectrophotometry with zero-crossing measurements and liquid chromatography. Benoxinate HCl was determined by measurement of its first derivative amplitude in mcllvaine's-citric acid phosphate buffer pH 7.0 at 268.4 and 272.4 nm in the presence of its alkali- and acid-induced degradation products, respectively. The acid- and alkali-induced, degradation products were determined by measurement of their first derivative amplitude in the same solvent at 307.5 nm. The LC method depends upon using a mu bondapak CN column with a mobile phase consisting of acetonitrile-water triethylamine (60:40:0.01, v/v) and adjusted to apparent pH 7. Quantitation was achieved with UV detection at 310 nm based on peak area. The proposed methods were utilized to investigate the kinetics of the acidic and alkaline degradation processes at different temperatures. The pH-rate profile of degradation of benoxinate HCl in Britton-Robinson buffer solutions was studied.

Experimental design for a basic mixture on a fluorinated packing. The effect of composition of the mobile phase.

PubMed

Wang, Y; Harrison, M; Clark, B J

2006-02-10

An optimization methodology is introduced for investigating the separation and the retention behavior of analytes on a new fluorinated reversed-phase packing. Ten basic compounds were selected as test probes to study the predictive models developed by using SPSS and MATLAB software. A two-level orthogonal array design (OAD) was used to extract significant parameters. The significant factors were optimised using a central composite design to obtain the quadratic relationship between the dependent and the independent variables. Using this strategy, response surfaces were derived as the 3D and contour plots, and mathematical models were defined for the separation. The models had a satisfactory coefficient (R(2) > 0.97, n = 16). For the test compounds, the best separation condition was: MeCN/30 mM phosphate buffer pH 7.1(55.5:44.5, v/v) and 10 basic solutes were resolved in 22 min. The significant influence of the concentration of buffer shows that different mechanisms of separation for basic compounds on the fluorinated packing exist compared with a common ODS stationary phase.

[Determination of penicillin intermediate and three penicillins in milk by high performance capillary electrophoresis].

PubMed

Tian, Chunqiu; Tan, Huarong; Gao, Liping; Shen, Huqin; Qi, Kezong

2011-11-01

A high performance capillary electrophoresis (HPCE) method was developed for the simultaneous determination of penicillin intermediate and penicillins in milk, including 6-amino-penicillanic acid (6-APA), penicillin G (PEN), ampicillin (AMP) and amoxicillin (AMO). The main parameters including the ion concentration and pH value of running buffer, separation voltage and column temperature were optimized systematically by orthogonal test. The four penicillins (PENs) were baseline separated within 4.5 min with the running buffer of 40 mmol/L potassium dihydrogen phosphate-20 mmol/L borax solution (pH 7.8), separation voltage of 28 kV and column temperature of 30 degrees C. The calibration curves showed good linearity in the range of 1.56 - 100 mg/L, and the correlation coefficients (r2) were between 0.9979 and 0.9998. The average recoveries at three spiked levels were in the range of 84.91% - 96.72% with acceptable relative standard deviations (RSDs) of 1.11% - 9.11%. The method is simple, fast, accurate and suitable for the determination of penicillins in real samples.

Agglomeration of Luminescent Porous Silicon Nanoparticles in Colloidal Solutions

NASA Astrophysics Data System (ADS)

Herynková, Kateřina; Šlechta, Miroslav; Šimáková, Petra; Fučíková, Anna; Cibulka, Ondřej

2016-08-01

We have prepared colloidal solutions of clusters composed from porous silicon nanoparticles in methanol, water and phosphate-buffered saline (PBS). Even if the size of the nanoclusters is between 60 and 500 nm, due to their highly porous "cauliflower"-like structure, the porous silicon nanoparticles are composed of interconnected nanocrystals having around 2.5 nm in size and showing strong visible luminescence in the orange-red spectral region (centred at 600-700 nm). Hydrophilic behaviour and good solubility of the nanoclusters in water and water-based solutions were obtained by adding hydrogen peroxide into the etching solution during preparation and 16 min long after-bath in hydrogen peroxide. By simple filtration of the solutions with syringe filters, we have extracted smaller nanoclusters with sizes of approx. 60-70 nm; however, these nanoclusters in water and PBS solution (pH neutral) are prone to agglomeration, as was confirmed by zeta potential measurements. When the samples were left at ambient conditions for several weeks, the typical nanocluster size increased to approx. 330-400 nm and then remained stable. However, both freshly filtered and aged samples (with agglomerated porous silicon nanoparticles) of porous silicon in water and PBS solutions can be further used for biological studies or as luminescent markers in living cells.

Agglomeration of Luminescent Porous Silicon Nanoparticles in Colloidal Solutions.

PubMed

Herynková, Kateřina; Šlechta, Miroslav; Šimáková, Petra; Fučíková, Anna; Cibulka, Ondřej

2016-12-01

We have prepared colloidal solutions of clusters composed from porous silicon nanoparticles in methanol, water and phosphate-buffered saline (PBS). Even if the size of the nanoclusters is between 60 and 500 nm, due to their highly porous "cauliflower"-like structure, the porous silicon nanoparticles are composed of interconnected nanocrystals having around 2.5 nm in size and showing strong visible luminescence in the orange-red spectral region (centred at 600-700 nm). Hydrophilic behaviour and good solubility of the nanoclusters in water and water-based solutions were obtained by adding hydrogen peroxide into the etching solution during preparation and 16 min long after-bath in hydrogen peroxide. By simple filtration of the solutions with syringe filters, we have extracted smaller nanoclusters with sizes of approx. 60-70 nm; however, these nanoclusters in water and PBS solution (pH neutral) are prone to agglomeration, as was confirmed by zeta potential measurements. When the samples were left at ambient conditions for several weeks, the typical nanocluster size increased to approx. 330-400 nm and then remained stable. However, both freshly filtered and aged samples (with agglomerated porous silicon nanoparticles) of porous silicon in water and PBS solutions can be further used for biological studies or as luminescent markers in living cells.

46 CFR Table 2 to Part 153 - Cargoes Not Regulated Under Subchapters D or O of This Chapter When Carried in Bulk on Non...

Code of Federal Regulations, 2012 CFR

2012-10-01

... Category 2-Amino-2-hydroxymethyl-1,3-propanediol solution III Ammonium hydrogen phosphate solution D...) D Ammonium phosphate, Urea solution, see also Urea, Ammonium phosphate solution D Ammonium..., Magnesium nitrate, Potassium chloride solution III Caramel solutions III Chlorinated paraffins (C14-C17...

Effect of bioglass 45S5 addition on properties, microstructure and cellular response of tetracalcium phosphate/monetite cements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stulajterova, R., E-mail: rstulajterova@saske.sk

Tetracalcium phosphate/nanomonetite (TTCPMH) cement composites with 7.5 and 15 wt% addition of melt-derived 45S5 bioactive glass were prepared by mechanical homogenization of powder components and 2% NaH{sub 2}PO{sub 4} solution was used as a hardening liquid. The properties of composites with the acidic (Ca/P ratio equal 1.5) or basic (Ca/P ratio equal 1.67) TTCPMH component were compared. Addition of glass component caused rapid rise in pH of composites up to 10. In microstructure of basic cement composite, the large bioglass particles weakly bounded to surrounding cement matrix were found contrary to a more compact microstructure of acidic cement composites withmore » the high number of spherical silica particles. Both the significant refinement of hydroxyapatite particles and the change to needle-like morphology with rise in the content of bioglass were identified in hydroxyapatite coatings created during soaking of composites in phosphate buffered saline. In acidic cement mixtures, the increase of compressive strength with an amount of bioglass was found whereas the opposite tendency was revealed in the case of basic cement mixtures. The higher concentrations of ions were verified in solutions after immersion of acidic cement composites. The severe cytotoxicity of extracts and composite cement substrates containing 15 wt% of bioglass demonstrated adverse effects of both the ionic concentrations and unappropriate surface texture on proliferation of mesenchymal stem cells. The enhanced ALP activities of cells cultured on composite cements confirmed the positive effect of bioactive glass addition on differentiation of mesenchymal stem cells. - Highlights: • Novel B45S5 bioglass/tetracalcium phosphate/nanomonetite cement composites • Cement basicity negatively affected their microstructure. • Acid composite cements had higher compressive strengths than basic composites. • Fast differentiation of MSC to osteoblast line on composite with 7.5 wt% of bioglass • Severe cytotoxicity of 24 h extracts from composites with 15 wt% of bioglass.« less

Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

NASA Astrophysics Data System (ADS)

Baldisserri, Carlo; Costa, Anna Luisa

2016-04-01

We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco's modified Eagle's medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu2+ ions or 15 nm CuO nanoparticles. Addition of either Cu2+ ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu2+ concentration in Cu2+-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu2+-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu2+-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu2+ ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

Anolyte recycling enhanced bioelectricity generation of the buffer-free single-chamber air-cathode microbial fuel cell.

PubMed

Ren, Yueping; Chen, Jinli; Shi, Yugang; Li, Xiufen; Yang, Na; Wang, Xinhua

2017-11-01

Anolyte acidification is an inevitable restriction for the bioelectricity generation of buffer-free microbial fuel cells (MFCs). In this work, acidification of the buffer-free KCl anolyte has been thoroughly eliminated through anolyte recycling. The accumulated HCO 3 - concentration in the recycled KCl anolyte was above 50mM, which played as natural buffer and elevated the anolyte pH to above 8. The maximum power density (P max ) increased from 322.9mWm -2 to 527.2mWm -2 , which is comparable with the phosphate buffered MFC. Besides Geobacter genus, the gradually increased anolyte pH and conductivity induced the growing of electrochemically active Geoalkalibacter genus, in the anode biofilm. Anolyte recycling is a feasible strategy to strengthen the self-buffering capacity of buffer-free MFCs, thoroughly eliminate the anolyte acidification and prominently enhance the electric power. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Determination of optical purity of alpha-phenylethylamine by high performance liquid chromatography with pre-column derivatization].

PubMed

Wang, Jinzhao; Zeng, Su; Wang, Danhua; Hu, Gongyun

2009-05-01

A simple pre-column derivatization-high performance liquid chromatographic (HPLC) method was established for the determination of optical purity of alpha-phenylethylamine. The enantiomers of alpha-phenylethylamine were derivatized with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC). The resulted diastereoisomers were separated on an Agilent Zorbax C18 column (250 mm x 4.6 mm, 5 microm) with a mobile phase of methanol-phosphate buffer (1.36 g/L aqueous solution of potassium dihydrogen phosphate, adjusted to pH 3.0 with concentrated phosphoric acid) (58:42, v/v). The flow rate was set at 1.0 mL/min and the detection wavelength was set at 241 nm. The method was linear from 0.15 - 15.0 mg/L for both enantiomers. The limit of detection and the limit of quantification were 0.05 mg/L and 0.15 mg/L, respectively. The relative standard deviations (RSDs) of inter- and intra-day determination were below 0.5%. The method is easy to handle, accurate, and suitable for the quality control of the optical purity of alpha-phenylethylamine.

Zn(II)-cyclam based chromogenic sensors for recognition of ATP in aqueous solution under physiological conditions and their application as viable staining agents for microorganism.

PubMed

Mahato, Prasenjit; Ghosh, Amrita; Mishra, Sanjiv K; Shrivastav, Anupama; Mishra, Sandhya; Das, Amitava

2011-05-02

Two chromogenic complexes, L.Zn (where L is (E)-4-((4-(1,4,8,11-tetraazacyclotetradecan-1-ylsulfonyl)phenyl)diazenyl)-N,N-dimethylaniline) and its [2]pseudorotaxane form (α-CD.L.Zn), were found to bind preferentially to adenosine triphosphate (ATP), among all other common anions and biologically important phosphate (AMP, ADP, pyrophosphate, and phosphate) ions in aqueous HEPES buffer medium of pH 7.2. Studies with live cell cultures of prokaryotic microbes revealed that binding of these two reagents to intercellular ATP, produced in situ, could be used in delineating the gram-positive and the gram-negative bacteria. More importantly, these dyes were found to be nontoxic to living microbes (eukaryotes and prokaryotes) and could be used for studying the cell growth dynamics. Binding to these two viable staining agents to intercellular ATP was also confirmed by spectroscopic studies on cell growth in the presence of different respiratory inhibitors that influence the intercellular ATP generation. © 2011 American Chemical Society

Comparative Toxicity of Preservatives on Immortalized Corneal and Conjunctival Epithelial Cells

PubMed Central

Ahdoot, Michael; Marcus, Edward; Asbell, Penny A.

2009-01-01

Abstract Purpose Nearly all eye drops contain preservatives to decrease contamination. Nonpreservatives such as disodium-ethylene diamine tetra-acetate (EDTA) and phosphate-buffered saline are also regularly added as buffering agents. These components can add to the toxicity of eye drops and cause ocular surface disease. To evaluate the potential toxicity of these common components and their comparative effects on the ocular surface, a tissue culture model utilizing immortalized corneal and conjunctival epithelial cells was utilized. Methods Immortalized human conjunctival and corneal epithelial cells were grown. At confluency, medium was replaced with 100 μL of varying concentrations of preservatives: benzalkonium chloride (BAK), methyl paraben (MP), sodium perborate (SP), chlorobutanol (Cbl), and stabilized thimerosal (Thi); varying concentrations of buffer: EDTA; media (viable control); and formalin (dead control). After 1 h, solutions were replaced with 150 μL of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide). After 4 h, solutions decanted, 100 μL of acid isopropanol added, and the optical density determined at 572 nm to evaluate cell viability. Results Conjunctival and corneal cell toxicity was seen with all preservatives. Depending upon concentration, BAK exhibited from 56% to 89% toxicity. In comparison, Cbl exhibited from 50% to 86%, MP from 30% to 76%, SP from 23% to 59%, and Thi from 70% to 95%. EDTA with minimal toxicity (from 6% to 59%) was indistinguishable from SP. Conclusions Generally, the order of decreasing toxicity at the most commonly used concentrations: Thi (0.0025%) > BAK (0.025%) > Cbl (0.25%) > MP (0.01%) > SP (0.0025%) ≈ EDTA (0.01%). Even at low concentration, these agents will cause some degree of ocular tissue damage. PMID:19284328

[Factors inducing transition from growth to dormancy in rhizobacteria Azospirillum brasilense].

PubMed

Kushneruk, M A; Tugarova, A V; Il'chukova, A V; Slavkina, E A; Starichkova, N I; Bogatyrev, V A; Antoniuk, L P

2013-01-01

The factors suppressing division of the cells of the rhizobacterium Azospirillum brasilense and inducing their transition to a dormant state were analyzed. These included the presence of hexylresorcinol or heavy metals (Cu and Co) in the medium, oxygen stress, and transfer of the cells into the physiological saline or phosphate buffer solution. The results were used to develop a protocol for obtaining of uncultured cells of A. brasilense Sp245, a natural symbiont of wheat. The cells lost their ability to grow on synthetic agar medium, but could revert to growth when incubated in freshly prepared liquid medium. Needle-shaped crystals differing from struvite, which has been previously reported for this strain, were found in the dormant culture of A. brasilense Sp245.

In-Vitro Corrosion Studies of Bioabsorbable Alloys

NASA Astrophysics Data System (ADS)

Gill, P.; Munroe, N.

Magnesium alloys have inspired a significant amount of attention from researchers all over the world for cardiovascular and orthopedic applications due to their light weight, mechanical integrity and degradation behavior. In this investigation, cast manufactured binary, ternary and quaternary magnesium alloys were studied for their degradation behavior by potentiodynamic polarization tests in phosphate buffer saline solution (PBS) and PBS containing amino acids (cysteine, C and tryptophan, W) at 37 °C. Electrochemical impedance spectroscopy (EIS) tests were performed to determine the charge transfer resistance and immersion tests were performed to assess corrosion rate and hydrogen evolution from the alloys. Furthermore, the surface morphology and surface chemistry of the alloys were observed by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Determination of morphine and codeine in urine using poly(dimethylsiloxane) microchip electrophoresis with electrochemical detection.

PubMed

Zhang, Qian-Li; Xu, Jing-Juan; Li, Xiang-Yun; Lian, Hong-Zhen; Chen, Hong-Yuan

2007-01-04

In this paper, a poly(dimethylsiloxane) (PDMS) microchip with electrochemical (EC) detection was developed for rapid separation and detection of morphine and codeine. It was found that morphine and codeine were well separated within 140 s in phosphate buffer solution (PBS) (pH 6.6, 40 mM)-beta-cyclodextrin (beta-CD) (20 mM)-acetonitrile (30%, v/v). The detection limit was 0.2 microM for morphine and 1 microM for codeine. The protocol was successfully applied to monitoring the amount of morphine and codeine in human urine. Compared with the conventional methods, the presented method had many advantages such as lower instrument cost, less reagent consumption and shorter analysis time.

Stretchable glucose biofuel cell with wirings made of multiwall carbon nanotubes

NASA Astrophysics Data System (ADS)

Fujimagari, Yusuke; Nishioka, Yasushiro

2015-12-01

In this study, we fabricated a flexible and stretchable glucose-biofuel cell with wirings made of multi wall carbon nanotube (MWCNTs) on a polydimethylsiloxane substrate. The biofuel cell investigated consists of a porous carbon anode (area of 30 mm2) modified by glucose oxidase and ferrocene, and a cathode (area of 30 mm2) modified by bilirubin oxidase. The anode and the cathode were connected with the MWCNT wirings. The maximum power of 0.31 μW at 76.6 mV, which corresponds to a power density of 1.04 μW/cm2, was realized by immersing the biofuel cell in a phosphate buffer solution with a glucose concentration of 100 mM, at room temperature.

Accelerated Hydrolysis of Aspirin Using Alternating Magnetic Fields

NASA Astrophysics Data System (ADS)

Reinscheid, Uwe M.

2009-08-01

The major problem of current drug-based therapy is selectivity. As in other areas of science, a combined approach might improve the situation decisively. The idea is to use the pro-drug principle together with an alternating magnetic field as physical stimulus, which can be applied in a spatially and temporarily controlled manner. As a proof of principle, the neutral hydrolysis of aspirin in physiological phosphate buffer of pH 7.5 at 40 °C was chosen. The sensor and actuator system is a commercially available gold nanoparticle (NP) suspension which is approved for animal usage, stable in high concentrations and reproducibly available. Applying the alternating magnetic field of a conventional NMR magnet system accelerated the hydrolysis of aspirin in solution.

In vitro evaluation of wound healing and antimicrobial potential of ozone therapy.

PubMed

Borges, Gabriel Álvares; Elias, Silvia Taveira; da Silva, Sandra Márcia Mazutti; Magalhães, Pérola Oliveira; Macedo, Sergio Bruzadelli; Ribeiro, Ana Paula Dias; Guerra, Eliete Neves Silva

2017-03-01

Although ozone therapy is extensively applied when wound repair and antimicrobial effect are necessary, little is known about cellular mechanisms regarding this process. Thus, this study aimed to evaluate ozone cytotoxicity in fibroblasts (L929) and keratinocytes (HaCaT) cell lines, its effects on cell migration and its antimicrobial activity. Cells were treated with ozonated phosphate-buffered saline (8, 4, 2, 1, 0.5 and 0.25 μg/mL ozone), chlorhexidine 0.2% or buffered-solution, and cell viability was determined through MTT assay. The effect of ozone on cell migration was evaluated through scratch wound healing and transwell migration assays. The minimum inhibitory concentrations for Candida albicans and Staphylococcus aureus were determined. Ozone showed no cytotoxicity for the cell lines, while chlorhexidine markedly reduced cell viability. Although no significant difference between control and ozone-treated cells was observed in the scratch assay, a considerable increase in fibroblasts migration was noticed on cells treated with 8 μg/mL ozonated solution. Ozone alone did not inhibit growth of microorganisms; however, its association with chlorhexidine resulted in antimicrobial activity. This study confirms the wound healing and antimicrobial potential of ozone therapy and presents the need for studies to elucidate the molecular mechanisms through which it exerts such biological effects. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Light Scattering Characterization of Elastin-Like Polypeptide Trimer Micelles

NASA Astrophysics Data System (ADS)

Tsuper, Ilona; Terrano, Daniel; Maraschky, Adam; Holland, Nolan; Streletzky, Kiril

The elastin-like polypeptides (ELP) nanoparticles are composed of three-armed star polypeptides connected by a negatively charged foldon. Each of the three arms extending from the foldon domain includes 20 repeats of the (GVGVP) amino acid sequence. The ELP polymer chains are soluble at room temperature and become insoluble at the transition temperature (close to 50 ° C), forming micelles. The size and shape of the micelle are dependent on the temperature and the pH of the solution, and on the concentration of the phosphate buffered saline (PBS). The depolarized dynamic light scattering (DDLS) was employed to study the structure and dynamics of micelles at 62 ° C. The solution was maintained at an approximate pH level of 7.3 - 7.5, while varying PBS concentration. At low salt concentrations (<15 mM), the micelle radius was about 10nm but not very reproducible on account of unstable pH levels arising from low buffer concentrations. At intermediate salt concentrations (15 - 60 mM), the system formed spherically-shaped micelles, exhibiting a steady growth in the hydrodynamic radius (Rh) from 10 to 21 nm, with increasing PBS concentration. Interestingly, higher salt concentrations (>60 mM) displayed an apparent elongation of the micelles evident by a significant VH signal, along with a surge in the apparent Rh. A model of micelle growth (and potential elongation) with increase in salt concentration is considered.

Tissue-engineered matrices as functional delivery systems: adsorption and release of bioactive proteins from degradable composite scaffolds.

PubMed

Cushnie, Emily K; Khan, Yusuf M; Laurencin, Cato T

2010-08-01

A tissue-engineered bone graft should imitate the ideal autograft in both form and function. However, biomaterials that have appropriate chemical and mechanical properties for grafting applications often lack biological components that may enhance regeneration. The concept of adding proteins such as growth factors to scaffolds has therefore emerged as a possible solution to improve overall graft design. In this study, we investigated this concept by loading porous hydroxyapatite-poly(lactide-co-glycolide) (HA-PLAGA) scaffolds with a model protein, cytochrome c, and then studying its release in a phosphate-buffered saline solution. The HA-PLAGA scaffold has previously been shown to be bioactive, osteoconductive, and to have appropriate physical properties for tissue engineering applications. The loading experiments demonstrated that the HA-PLAGA scaffold could also function effectively as a substrate for protein adsorption and release. Scaffold protein adsorptive loading (as opposed to physical entrapment within the matrix) was directly related to levels of scaffold HA-content. The HA phase of the scaffold facilitated protein retention in the matrix following incubation in aqueous buffer for periods up to 8 weeks. Greater levels of protein retention time may improve the protein's effective activity by increasing the probability for protein-cell interactions. The ability to control protein loading and delivery simply via composition of the HA-PLAGA scaffold offers the potential of forming robust functionalized bone grafts. (c) 2010 Wiley Periodicals, Inc.

Application and comparison of high performance liquid chromatography and high speed counter-current chromatography in enantioseparation of (±)-2-phenylpropionic acid.

PubMed

Tong, Shengqiang; Zheng, Ye; Yan, Jizhong

2013-03-15

High performance liquid chromatography (HPLC) and high speed counter-current chromatography (HSCCC) were applied and compared in enantioseparation of 2-phenylpropionic acid (2-PPA) when hydroxypropyl-β-cyclodextrin (HP-β-CD) was used as chiral mobile phase additive. For HPLC, the enantioseparation was achieved on ODS C(18) reverse phase column and the mobile phase was 25 mmol L(-1) HP-β-CD aqueous buffer solution (pH 4.0, adjusted with triethylamine): methanol: glacial acetic acid (85:15:0.5 (v/v/v)). For HSCCC, the two-phase solvent system was composed of n-hexane-ethyl acetate-0.1 mol L(-1) phosphate buffer solution pH2.67 (5:5:10 for isocratic elution and 8:2:10 for recycling elution (v/v/v)) added with 0.1 mol L(-1) HP-β-CD. The key parameters, such as a substitution degree of HP-β-CD, the concentration of HP-β-CD, pH value of the aqueous phase and the temperature were optimized for both separation methods. Using the optimum conditions a complete HSCCC enantioseparation of 40 mg of 2-propylpropionic acid in a recycling elution mode gave 15-18 mg of (+)-2-PPA and (-)-2-PPA enantiomers with 95-98% purity and 85-93% recovery. Copyright © 2013 Elsevier B.V. All rights reserved.

Enantioselective separation of chiral aromatic amino acids with surface functionalized magnetic nanoparticles.

PubMed

Ghosh, Sudipa; Fang, Tan Hui; Uddin, M S; Hidajat, K

2013-05-01

Chiral resolution aromatic amino acids, DL-tryptophan (DL-Trp), DL-phenylalanine (DL-Phe), DL-tyrosine (DL-Tyr) from phosphate buffer solution was achieved in present study employing the concept of selective adsorption by surface functionalized magnetic nanoparticles (MNPs). Surfaces of magnetic nanoparticles were functionalized with silica and carboxymethyl-β-cyclodextrin (CMCD) to investigate their adsorption resolution characteristics. Resolution of enantiomers from racemic mixture was quantified in terms of enantiomeric excess using chromatographic method. The MNPs selectively adsorbed L-enantiomers of DL-Trp, DL-Phe, and DL-Tyr from racemic mixture and enantiomeric excesses (e.e.) were determined as 94%, 73% and 58%, respectively. FTIR studies demonstrated that hydrophobic portion of enantiomer penetrated into hydrophobic cavity of cyclodextrin molecules to form inclusion complex. Furthermore, adsorption site was explored using XPS and it was revealed that amino group at chiral center of the amino acid molecule formed hydrogen bond with secondary hydroxyl group of CMCD molecule and favorability of hydrogen bond formation resulted in selective adsorption of L-enantiomer. Finally, stability constant (K) and Gibbs free energy change (-ΔG°) for inclusion complexation of CMCD with L-/D-enantiomers of amino acids were determined using spectroflurometry in aqueous buffer solution. Higher binding constants were obtained for inclusion complexation of CMCD with L-enantiomers compared to D-enantiomers which stimulated enantioselective properties of CMCD functionalized magnetite silica nanoparticles. Copyright © 2013 Elsevier B.V. All rights reserved.

Polymeric micellar pH-sensitive drug delivery system for doxorubicin.

PubMed

Hrubý, Martin; Konák, Cestmír; Ulbrich, Karel

2005-03-02

A novel polymeric micellar pH-sensitive system for delivery of doxorubicin (DOX) is described. Polymeric micelles were prepared by self-assembly of amphiphilic diblock copolymers in aqueous solutions. The copolymers consist of a biocompatible hydrophilic poly(ethylene oxide) (PEO) block and a hydrophobic block containing covalently bound anthracycline antibiotic DOX. The starting block copolymers poly(ethylene oxide)-block-poly(allyl glycidyl ether) (PEO-PAGE) with a very narrow molecular weight distribution (Mw/Mn ca. 1.05) were prepared by anionic ring opening polymerization using sodium salt of poly(ethylene oxide) monomethyl ether as macroinitiator and allyl glycidyl ether as functional monomer. The copolymers were covalently modified via reactive double bonds by the addition of methyl sulfanylacetate. The resulting ester subsequently reacted with hydrazine hydrate yielding polymer hydrazide. The hydrazide was coupled with DOX yielding pH-sensitive hydrazone bonds between the drug and carrier. The resulting conjugate containing ca. 3 wt.% DOX forms micelles with Rh(a)=104 nm in phosphate-buffered saline. After incubation in buffers at 37 degrees C DOX was released faster at pH 5.0 (close to pH in endosomes; 43% DOX released within 24 h) than at pH 7.4 (pH of blood plasma; 16% DOX released within 24 h). Cleavage of hydrazone bonds between DOX and carrier continues even after plateau in the DOX release from micelles incubated in aqueous solutions is reached.

High performance liquid chromatography for the simultaneous analysis of penicillin residues in beef and milk using ion-paired extraction and binary water-acetonitrile mixture.

PubMed

Kukusamude, Chunyapuk; Burakham, Rodjana; Chailapakul, Orawon; Srijaranai, Supalax

2012-04-15

An ion-paired extraction (IPE) has been developed for the analysis of penicillin antibiotics (penicillin G, oxacillin and cloxacillin) in beef and milk samples using tetrabutylammonium bromide (TBABr) as ion-pairing agent and binary water-acetonitrile as extractant. The factors affecting the IPE efficiency were optimized including solution pH, volume of acetonitrile (ACN), concentration of TBABr and electrolyte salt (NH(4))(2)SO(4). The optimum IPE conditions were 10 mmol L(-1) phosphate buffer pH 8, 2 mL of ACN, 6 mmol L(-1) of TBABr and 2.5 mL of saturated ammonium sulfate. Under the HPLC condition: an Xbridge™ C18 reversed-phase column, isocratic elution of 5 mmol L(-1) phosphate buffer (pH 6.6) and acetonitrile (75:25, v/v) and a flow rate of 1 mL min(-1), with UV detection at 215 nm, the separation of three penicillins was achieved within 10 min. Under the selected optimum conditions, the enhancement of 21-53 folds compared to that without preconcentration and limits of detection (LODs) of 1-2 ng mL(-1) were obtained. Good reproducibility was achieved with RSD<2% for retention time and <5% for slope of calibration curves. The average recoveries higher than 85% were obtained. The proposed IPE-HPLC method has shown to be high efficient preconcentration and analysis method for penicillin residues in beef and milk with LOD lower than the maximum residue limits. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of Temperature on the Colloidal Stability of Polymer-Coated Gold Nanoparticles in Cell Culture Media.

PubMed

Zyuzin, Mikhail V; Honold, Tobias; Carregal-Romero, Susana; Kantner, Karsten; Karg, Matthias; Parak, Wolfgang J

2016-04-06

The temperature-dependence of the hydrodynamic diameter and colloidal stability of gold-polymer core-shell particles with temperature-sensitive (poly(N-isopropylacrylamide)) and temperature-insensitive shells (polyallylaminine hydrochloride/polystyrensulfonate, poly(isobutylene-alt-maleic anhydride)-graft-dodecyl) are investigated in various aqueous media. The data demonstrate that for all nanoparticle agglomeration, i.e., increase in effective nanoparticle size, the presence of salts or proteins in the dispersion media has to be taken into account. Poly(N-isopropylacrylamide) coated nanoparticles show a reversible temperature-dependent increase in size above the volume phase transition of the polymer shell when they are dispersed in phosphate buffered saline or in media containing protein. In contrast, the nanoparticles coated with temperature-insensitive polymers show a time-dependent increase in size in phosphate buffered saline or in medium containing protein. This is due to time-dependent agglomeration, which is particularly strong in phosphate buffered saline, and induces a time-dependent, irreversible increase in the hydrodynamic diameter of the nanoparticles. This demonstrates that one has to distinguish between temperature- and time-induced agglomerations. Since the size of nanoparticles regulates their uptake by cells, temperature-dependent uptake of thermosensitive and non-thermosensitive nanoparticles by cells lines is compared. No temperature-specific difference between both types of nanoparticles could be observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A calorimetric investigation of the interaction of the lac repressor with inducer.

PubMed

Donnér, J; Caruthers, M H; Gill, S J

1982-12-25

A calorimetric study has been made of the interaction between the lac repressor and isopropyl-1-thio-beta-D-galactopyranoside (IPTG). The buffer-corrected enthalpy of reaction at 25 degrees C was found to be -15.6, -24.7, -4.6 kJ/mol of bound IPTG at pH 7.0, pH 8.1, and pH 9.0, respectively. This large range of enthalpy values is in contrast to a maximum difference in the free energy of the reaction of only 1.5 kJ/mol of bound IPTG between these pH values. The reaction was found by calorimetric measurements in different buffers to be accompanied by an uptake of 0.29 mol of protons/mol of bound IPTG at pH 8.1. The pH dependency of the reaction enthalpy suggests differences in the extent of protonation of the binding site and the involvement of H bonding with IPTG. The lack of strong hydrophobic contributions in the IPTG binding process is revealed by the absence of any determinable heat capacity change for the reaction at pH 7.0. The presence of phosphate buffer significantly alters the enthalpy of IPTG binding at higher pH values, but has little effect upon the binding constant. This implies that highly negative phosphate species change the nature of the IPTG binding site without any displacement of phosphate upon IPTG binding.

Ultrastructure of hybrid chitosan-glycerol phosphate blood clots by environmental scanning electron microscopy.

PubMed

Iliescu, M; Hoemann, C D; Shive, M S; Chenite, A; Buschmann, M D

2008-03-01

Chitosan-based polymers have been extensively studied for biomedical applications. Recently, liquid solutions of chitosan in a glycerol phosphate buffer (chitosan-GP) with physiological pH and osmolality were mixed with autologous blood to form hybrid chitosan-GP/blood implants that improved the repair of articular cartilage lesions in a large animal model. The mixture of chitosan-GP and blood forms a viscous liquid, which solidifies in minutes via normal blood coagulation as well as chitosan-mediated mechanisms. Here we have examined the ultrastructure of these chitosan-GP/blood clots as well as regular blood clots and chitosan-GP gels, the latter produced by heating. Both unfixed and fixed samples of chitosan-GP/blood clots, regular blood clots, and chitosan-GP gels were investigated by environmental scanning electron microscopy (ESEM) in conjunction with energy dispersive X-ray spectrometry (EDS), the former permitting direct observation of the ultrastructure in hydrated conditions simulating the natural state. By examination of unfixed specimens using ESEM we found that chitosan formed a network structure in both chitosan-GP gels and chitosan-GP/blood clots; however this structure was altered by aldehyde fixation to produce artifactual aggregates of chitosan microparticles. We were also able to identify chitosan in chitosan-GP/blood clots by washing samples in low concentration NaCl solutions followed by local EDS analyses to identify excess chloride versus sodium, and thus presence of cationic chitosan in analyzed features. Additional results indicated that the majority of glycerol phosphate diffuses freely from chitosan-GP gels (by EDS of phosphorus) and that hyperosmotic paraformaldehyde-based fixatives (i.e. 4% w/v) significantly disturb erythrocyte morphology in fixed whole blood clots. (c) 2007 Wiley-Liss, Inc.

Sensitive life detection strategies for low-biomass environments: optimizing extraction of nucleic acids adsorbing to terrestrial and Mars analogue minerals.

PubMed

Direito, Susana O L; Marees, Andries; Röling, Wilfred F M

2012-07-01

The adsorption of nucleic acids to mineral matrixes can result in low extraction yields and negatively influences molecular microbial ecology studies, in particular for low-biomass environments on Earth and Mars. We determined the recovery of nucleic acids from a range of minerals relevant to Earth and Mars. Clay minerals, but also other silicates and nonsilicates, showed very low recovery (< 1%). Consequently, optimization of DNA extraction was directed towards clays. The high temperatures and acidic conditions used in some methods to dissolve mineral matrices proved to destruct DNA. The most efficient method comprised a high phosphate solution (P/EtOH; 1 M phosphate, 15% ethanol buffer at pH 8) introduced at the cell-lysing step in DNA extraction, to promote chemical competition with DNA for adsorption sites. This solution increased DNA yield from clay samples spiked with known quantities of cells up to nearly 100-fold. DNA recovery was also enhanced from several mineral samples retrieved from an aquifer, while maintaining reproducible DGGE profiles. DGGE profiles were obtained for a clay sample for which no profile could be generated with the standard DNA isolation protocol. Mineralogy influenced microbial community composition. The method also proved suitable for the recovery of low molecular weight DNA (< 1.5 kb). © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Release of mitochondrial glutathione and calcium by a cyclosporin A-sensitive mechanism occurs without large amplitude swelling.

PubMed

Savage, M K; Reed, D J

1994-11-15

Treatment of isolated mitochondria with calcium and inorganic phosphate induces inner membrane permeability that is thought to be mediated through a non-selective, calcium-dependent pore. The inner membrane permeability results in the rapid efflux of small matrix solutes such as glutathione and calcium, loss of coupled functions, and large amplitude swelling. We have identified conditions of permeability transition without large amplitude swelling, a parameter often used to assess inner membrane permeability. The addition of either oligomycin, antimycin, or sulfide to incubation buffer containing calcium and inorganic phosphate abolished large-amplitude swelling of mitochondria but did not prevent inner membrane permeability as demonstrated by the release of mitochondrial glutathione and calcium. The release of both glutathione and calcium was inhibited by the addition of cyclosporin A, a potent inhibitor of permeability transition. Transmission electron microscopy analysis, combined with the glutathione and calcium release data, indicate that permeability transition can be observed in the absence of large-amplitude swelling. Permeability transition occurring both with and without large-amplitude swelling was accompanied by a collapse of the membrane potential. We conclude that cyclosporin A-sensitive permeability transition can occur without obvious morphological changes such as large-amplitude swelling. Monitoring the cyclosporin A-sensitive release of concentrated endogenous matrix solutes, such as GSH, may be a sensitive and useful indicator of permeability transition.

Assessment of solubilization characteristics of different surfactants for carvedilol phosphate as a function of pH.

PubMed

Chakraborty, Subhashis; Shukla, Dali; Jain, Achint; Mishra, Brahmeshwar; Singh, Sanjay

2009-07-15

The effect of surfactants on the solubility of a new phosphate salt of carvedilol was investigated at different biorelevent pH to evaluate their solubilization capacity. Solutions of different classes of surfactants viz., anionic-sodium dodecyl sulfate (SDS) and sodium taurocholate (STC), cationic-cetyltrimethylammonium bromide (CTAB) and non-ionic-Tween 80 (T80) were prepared in the concentration range of 5-35 mmol dm(-3) in buffer solutions of pH 1.2, 3.0, 4.5, 5.8, 6.8 and 7.2. The solubility data were used to calculate the solubilization characteristics viz. molar solubilization capacity, water micelle partition coefficient, free energy of solubilization and binding constant. Solubility enhancement in basic pH was in following order: CTAB>T80>SDS>STC. CTAB and T80 showed remarkable solubility enhancement in acidic pH as well. Among the anionic surfactants, solubility in acidic medium was retarded except at pH 1.2 in case of SDS. Cationic and non-ionic surfactants were found to be suitable for enhancing the solubility of CP which can be employed for maintaining the in vitro sink condition in the basic dissolution medium. While anionic surfactants showed solubility retardant behavior which may be exploited in increasing the drug entrapment efficiency of a colloidal drug delivery system formulated by emulsification technique.

Recovery of phosphate from aqueous solution by magnesium oxide decorated magnetic biochar and its potential as phosphate-based fertilizer substitute.

PubMed

Li, Ronghua; Wang, Jim J; Zhou, Baoyue; Awasthi, Mukesh Kumar; Ali, Amjad; Zhang, Zengqiang; Lahori, Altaf Hussain; Mahar, Amanullah

2016-09-01

The present study deals with the preparation of a novel MgO-impregnated magnetic biochar (MMSB) for phosphate recovery from aqueous solution. The MMSB was evaluated against sugarcane harvest residue biochar (SB) and magnetic biochar without Mg (MSB). The results showed that increasing Mg content in MMSB greatly improved the phosphate adsorption compared to SB and MSB, with 20% Mg-impregnated MMSB (20MMSB) recovering more than 99.5% phosphate from aqueous solution. Phosphate adsorption capacity of 20MMSB was 121.25mgP/g at pH 4 and only 37.53% of recovered phosphate was desorbed by 0.01mol/L HCl solutions. XRD and FTIR analysis showed that phosphate sorption mechanisms involved predominately with surface electrostatic attraction and precipitation with impregnated MgO and surface inner-sphere complexation with Fe oxide. The 20MMSB exhibited both maximum phosphate sorption and strong magnetic separation ability. Overall, phosphate-loaded 20MMSB significantly enhanced plant growth and could be used as a potential substitute for phosphate-based fertilizer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fibril growth kinetics link buffer conditions and topology of 3D collagen I networks.

PubMed

Kalbitzer, Liv; Pompe, Tilo

2018-02-01

Three-dimensional fibrillar networks reconstituted from collagen I are widely used as biomimetic scaffolds for in vitro and in vivo cell studies. Various physicochemical parameters of buffer conditions for in vitro fibril formation are well known, including pH-value, ion concentrations and temperature. However, there is a lack of a detailed understanding of reconstituting well-defined 3D network topologies, which is required to mimic specific properties of the native extracellular matrix. We screened a wide range of relevant physicochemical buffer conditions and characterized the topology of the reconstituted 3D networks in terms of mean pore size and fibril diameter. A congruent analysis of fibril formation kinetics by turbidimetry revealed the adjustment of the lateral growth phase of fibrils by buffer conditions to be key in the determination of pore size and fibril diameter of the networks. Although the kinetics of nucleation and linear growth phase were affected by buffer conditions as well, network topology was independent of those two growth phases. Overall, the results of our study provide necessary insights into how to engineer 3D collagen matrices with an independent control over topology parameters, in order to mimic in vivo tissues in in vitro experiments and tissue engineering applications. The study reports a comprehensive analysis of physicochemical conditions of buffer solutions to reconstitute defined 3D collagen I matrices. By a combined analysis of network topology, i.e., pore size and fibril diameter, and the kinetics of fibril formation we can reveal the dependence of 3D network topology on buffer conditions, such as pH-value, phosphate concentration and sodium chloride content. With those results we are now able to provide engineering strategies to independently tune the topology parameters of widely used 3D collagen scaffolds based on the buffer conditions. By that, we enable the straightforward mimicking of extracellular matrices of in vivo tissues for in vitro cell culture experiments and tissue engineering applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Molecular Structure and Equilibrium Forces of Bovine Submaxillary Mucin Adsorbed at a Solid-Liquid Interface.

PubMed

Zappone, Bruno; Patil, Navinkumar J; Madsen, Jan B; Pakkanen, Kirsi I; Lee, Seunghwan

2015-04-21

By combining dynamic light scattering, circular dichroism spectroscopy, atomic force microscopy, and surface force apparatus, the conformation of bovine submaxillary mucin in dilute solution and nanomechanical properties of mucin layers adsorbed on mica have been investigated. The samples were prepared by additional chromatographic purification of commercially available products. The mucin molecule was found to have a z-average hydrodynamic diameter of ca. 35 nm in phosphate buffered solution, without any particular secondary or tertiary structure. The contour length of the mucin is larger than, yet of the same order of magnitude as the diameter, indicating that the molecule can be modeled as a relatively rigid polymeric chain due to the large persistence length of the central glycosylated domain. Mucin molecules adsorbed abundantly onto mica from saline buffer, generating polymer-like, long-ranged, repulsive, and nonhysteretic forces upon compression of the adsorbed layers. Detailed analysis of such forces suggests that adsorbed mucins had an elongated conformation favored by the stiffness of the central domain. Acidification of aqueous media was chosen as means to reduce mucin-mucin and mucin-substrate electrostatic interactions. The hydrodynamic diameter in solution did not significantly change when the pH was lowered, showing that the large persistence length of the mucin molecule is due to steric hindrance between sugar chains, rather than electrostatic interactions. Remarkably, the force generated by an adsorbed layer with a fixed surface coverage also remained unaltered upon acidification. This observation can be linked to the surface-protective, pH-resistant role of bovine submaxillary mucin in the variable environmental conditions of the oral cavity.

Effect of number and washing solutions on functional properties of surimi-like material from duck meat.

PubMed

Ramadhan, Kurnia; Huda, Nurul; Ahmad, Ruzita

2014-02-01

Duck meat is less utilized than other meats in processed products because of limitations of its functional properties, including lower water holding capacity, emulsion stability, and higher cooking loss compared with chicken meat. These limitations could be improved using surimi technology, which consists of washing and concentrating myofibrillar protein. In this study, surimi-like materials were made from duck meat using two or three washings with different solutions (tap water, sodium chloride, sodium bicarbonate, and sodium phosphate buffer). Better improvement of the meat's functional properties was obtained with three washings versus two washings. Washing with tap water achieved the highest gel strength; moderate elevation of water holding capacity, pH, lightness, and whiteness; and left a small amount of fat. Washing with sodium bicarbonate solution generated the highest water holding capacity and pH and high lightness and whiteness values, but it resulted in the lowest gel strength. Processing duck meat into surimi-like material improves its functional properties, thereby making it possible to use duck meat in processed products.

Non-enzymatic browning reaction of glucosamine at mild conditions: Relationship between colour formation, radical scavenging activity and α-dicarbonyl compounds production.

PubMed

Hong, Pui Khoon; Betti, Mirko

2016-12-01

Glucosamine (GlcN, 5% w/v) was incubated in either phosphate buffer or ammonium hydroxide solutions at 40 and 60°C for up to 48h in order to yield caramel solutions. Non-enzymatic browning was monitored via changes in absorption at 280, 320 and 420nm and the physico-chemical properties as well as the generation of short chain α-dicarbonyl compounds were evaluated. Accumulation of GlcN autocondensation products (280nm) proceeded in parallel with the development of pre-melanoidins (320nm) and melanoidins (420nm). The reactive α-dicarbonyls were detected at temperature as low as 40°C within 3h with a maximum level of diacetyl recorded at 6h. The caramel solutions showed a high efficacy in scavenging DPPH and ABTS radicals in accordance with the increasing browning intensity. The results suggest that GlcN browning can be modulated according to the specific desired properties to produce a multi-functional food ingredient that has health-promoting effects. Copyright © 2016 Elsevier Ltd. All rights reserved.

Solution Properties of Amphoteric Random Copolymers Bearing Pendant Sulfonate and Quaternary Ammonium Groups with Controlled Structures.

PubMed

Nakahata, Rina; Yusa, Shin-Ichi

2018-01-05

Amphoteric random copolymers P(AMPS/APTAC50) x , where x = 41, 89, and 117, composed of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) and 3-acrylamidopropyltrimethylammonium chloride (APTAC) were prepared via reversible addition-fragmentation chain transfer radical polymerization. P(AMPS/APTAC50) x can dissolve in pure water to form small interpolymer aggregates. In aqueous solutions of NaCl, P(AMPS/APTAC50) x can dissolve in the unimer state. Amphoteric random copolymer P(AMPS/APTAC50) c with high molecular weight was prepared via conventional free-radical polymerization. Although P(AMPS/APTAC50) c cannot dissolve in pure water, it can dissolve in aqueous solutions of NaCl. In amphoteric random copolymers with high molecular weight, the possibility of continuous sequences of monomers with the same charge may increase, which may cause strong interactions between polymer chains. When fetal bovine serum (FBS) and polyelectrolytes were mixed in phosphate-buffered saline, the hydrodynamic radius and light-scattering intensity increased. There was no interaction between P(AMPS/APTAC50) x and FBS because corresponding increases could not be observed.

Gelatin and galactomannan-based scaffolds: Characterization and potential for tissue engineering applications.

PubMed

Siqueira, Nataly M; Paiva, Bruno; Camassola, Melissa; Rosenthal-Kim, Emily Q; Garcia, Ketlin C; dos Santos, Francisco P; Soares, Rosane M D

2015-11-20

In this work, we produced gelatin films containing different concentrations of galactomannan by casting solutions. The films were crosslinked by immersion in 30mM solution of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC). The crosslinking of gelatin-containing films was confirmed by the reduction of free amine band intensity (3400-3200cm(-1)) in the GEL IR, as well as by the evaluation of its behavior when immersed in phosphate-buffer solution. The crosslinking of galactomannan film was confirmed by the formation of new ether bonds, as observed by increasing intensity of the band at 1148cm(-1), and the reduction of OH band intensity (3600-3200cm(-1)). The presence of galactomannan and the crosslinking mediated by EDC were responsible to improve elasticity in the gelatin-based films. The samples did not show cytotoxicity during 24h or 48h. In addition, rat mesenchymal stem cells adhered to the films regardless of galactomannan concentration. The results indicated that the gelatin/galactomannan films are potential biomaterials for use as scaffolds for tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

In vitro corrosion behaviour and microhardness of high-copper amalgams with platinum and indium.

PubMed

Ilikli, B G; Aydin, A; Işimer, A; Alpaslan, G

1999-02-01

Samples prepared from Luxalloy, GS-80, Permite-C and Logic and polished after 24 h by traditional methods were stored in polypropylene tubes containing phosphate-buffered saline solutions (pH 3.5 and 6.5) and distilled water. The amounts of mercury, silver, tin, copper, zinc, platinum and indium in the test solutions were determined at the first, second, eighth, 52nd and 78th week by atomic absorption spectrometry. At the end of the eighth week the amalgam samples were removed from solutions and evaluated by Rockwell Super Scial Microhardness tester. Statistically significant low amounts of metal ions were measured for Permite-C containing indium and Logic containing platinum. The microhardness test results showed that there were statistically significant increases in the microhardness of Permite-C and Logic. As a result it was shown that the amalgam samples were affected from corrosion conditions to different degrees. Sample of the Logic group that was stored in distilled water, showed smoother surface properties than other amalgam samples containing high copper. However, it was observed that samples of Permite-C group had the smoothest surface properties.

3D ordered porous MoxC (x = 1 or 2) for advanced hydrogen evolution and Li storage.

PubMed

Yu, Hong; Fan, Haosen; Wang, Jiong; Zheng, Yun; Dai, Zhengfei; Lu, Yizhong; Kong, Junhua; Wang, Xin; Kim, Young Jin; Yan, Qingyu; Lee, Jong-Min

2017-06-01

3D ordered porous structures of Mo x C are prepared with different Mo to C ratios and tested for two possible promising applications: hydrogen evolution reaction (HER) through water splitting and lithium ion batteries (LIBs). Mo 2 C and MoC with 3D periodic ordered structures are prepared with a similar process but different precursors. The 3D ordered porous MoC exhibits excellent cycling stability and rate performance as an anode material for LIBs. A discharge capacity of 450.9 mA h g -1 is maintained up to 3000 cycles at 10.0 A g -1 . The Mo 2 C with a similar ordered porous structure shows impressive electrocatalytic activity for the HER in neutral, alkaline and acidic pH solutions. In particular, Mo 2 C shows an onset potential of only 33 mV versus a reversible hydrogen electrode (RHE) and a Tafel slope of 42.5 mV dec -1 in a neutral aqueous solution (1.0 M phosphate buffer solution), which is approaching that of the commercial Pt/C catalyst.

Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester

NASA Technical Reports Server (NTRS)

Weber, A. L.

1986-01-01

The autocondensation of the glyceroyl thioester, S-glyceroyl-ethane-thiol, yielded olioglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid in imidazole buffers as compared to 2,6-lutidine and phosphate buffers. The efficiency of ester bond synthesis was about 20% for 40 mM S-glyceroyl-ethane-thiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the olioglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.

Radiotherapy Measurements with a Deoxyribonucleic Acid Doublestrand-Break Dosimeter

NASA Astrophysics Data System (ADS)

Obeidat, Mohammad Ali

Many types of dosimeters are used in the clinic to measure radiation dose for therapy but none of them directly measures the biological effect of this dose. The overall purpose of this work was to develop a dosimeter that measures biological damage in the form of double-strand breaks to deoxyribonucleic acid. This dosimeter could provide a more biologically relevant measure of radiation damage than the currently utilized dosimeters. A pair of oligonucleotides was designed to fabricate this dosimeter. One is labeled with a 5'-end biotin and the other with a 5'-end 6 Fluorescein amidite (fluorescent dye excited at 495?nanometer, with a peak emission at 520 nanometer). These were designed to adhere to certain locations on the pRS316 vector and serve as the primers for polymerase chain reactions. The end product of this reaction is a 4 kilo-base pair double strands deoxyribonucleic acid fragment with biotin on one end and 6 Fluorescein amidite oligonucleotide on the other attached to streptavidin beads. The biotin end connects the double strands deoxyribonucleic acid to the streptavidin bead. These bead-connected double strands deoxyribonucleic acid were suspended in 50 microliter of phosphate-buffered saline and placed into a tube for irradiation. Following irradiation of the deoxyribonucleic acid dosimeter, we take advantage of the magnetic properties of the streptavidin bead by placing our sample microtube against a magnet. The magnetic field pulls the streptavidin beads against the side of the tube. If a double-strand-break has occurred for a double strands deoxyribonucleic acid, the fluorescein end of the double strands deoxyribonucleic acid becomes free and is no longer attached to the bead or held against the side of the microtube. The free fluorescein following a double-strand-break in double strands deoxyribonucleic acid is referred to here as supernatant. The supernatant is extracted and placed in another microtube, while the unbroken double strands deoxyribonucleic acid remain attached to the beads and stay in the microtube (Fig. 4). Those beads were re-suspended with 50 microliter of phosphate-buffered saline again (called beads), then we placed both supernatant and beads in a reader microplate and we read the fluorescence signal for both with a fluorescence reader (BioTek Synergy 2). These beads and supernatant fluorescence signals are denoted by B and S, respectively. The relative amount of supernatant fluorescence counts is proportional to the probability of a double-strand-break. The probability of double-strand-break was calculated with the following equation: (S-BG)/(S+B-2BG) (1). where S was the supernatant fluorescence intensity (related to the number of double strands deoxyribonucleic acid with double-strand breaks), B was the re-suspended beads fluorescence intensity (related to the number of double strands deoxyribonucleic acid without double-strand breaks), and BG was the phosphate-buffered saline fluorescence intensity (related to the background signal). There are two advantages that this type of dosimeter has over the gel separation technique. First, it is important to irradiate deoxyribonucleic acid in a solution that has similar osmolarity and ion concentrations to that in a human, such as phosphate-buffered saline. A gel dosimeter would require a transfer to gel to separate deoxyribonucleic acid, whereas our dosimeter can be separated in this solution. Currently, we use pipettes to manually perform this separation, but this step could be automated. Second, the magnetic deoxyribonucleic acid separation technique is much faster than that for gel electrophoresis. Calibration of radiotherapy equipment isn't something that happens in national science laboratories, with only world-leading experts. This is something that happens locally at every cancer clinic, with physicists that do not have the luxury of focusing solely on this one measurement. For this reason, ease of use is critical for this type of technology. (Abstract shortened by ProQuest.).

Bioactive calcium phosphate-based glasses and ceramics and their biomedical applications: A review.

PubMed

Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

2017-01-01

An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented.

Comparative studies in electrochemical degradation of sulfamethoxazole and diclofenac in water by using various electrodes and phosphate and sulfate supporting electrolytes.

PubMed

Sifuna, Fred W; Orata, Francis; Okello, Veronica; Jemutai-Kimosop, Selly

2016-09-18

In this study, the electro-oxidation capacities of Na2SO4 and potassium phosphate buffer supporting electrolytes were tested and compared for destruction of the sulfamethoxazole (SMX) and diclofenac (DCF) on platinum (Pt) electrode and graphite carbon electrode in aqueous medium. The suitability of pharmaceutical active compounds (PhACs) for electrochemical oxidation was tested by cyclic voltammetry (CV) technique performed in the potential range -1.5 to +1.5 V versus Ag/AgCl, which confirmed the electro-activity of the selected PhACs. The degradation and mineralization were monitored by ultraviolet (UV)-Vis spectrophotometry and HPLC. 0.1 M Na2SO4 supporting electrolyte was found to be more effective for mineralization of SMX and DCF, with efficiency of 15-30% more than the 0.1 M phosphate buffer supporting electrolyte on the platinum (Pt) and carbon electrodes. The Pt electrode showed better performance in the degradation of the two PhACs while under the same conditions than the carbon electrode for both 0.1 M Na2SO4 and 0.1 M potassium phosphate buffer supporting electrolytes. The SMX and DCF degradation kinetics best fitted the second-order reaction, with rate constants ranging between 0.000389 and 0.006 mol(2) L(-2) min(-1) and correlation coefficient (R(2)) above 0.987. The second-order degradation kinetics indicated that the rate-determining step in the degradation could be a chemical process, thus suggesting the active involvement of electrolyte radical species in the degradation of SMX and DCF. Results obtained from a real field sample showed a more than 98% removal of the PhACs from the wastewater by electrochemical degradation.

Structural characterization and dissolution profile of mycophenolic acid cocrystals.

PubMed

Zeng, Qing-Zhu; Ouyang, Jian; Zhang, Shuo; Zhang, Lei

2017-05-01

Three novel cocrystals of mycophenolic acid (MPA) with isonicotinamide (MPA-ISO), minoxidil (MPA-MIN) and 2,2'-dipyridylamine (MPA-DPA) as coformers have been prepared successfully by both slow evaporation and liquid-assisted grinding. The structures of these cocrystals show that all the three coformers form hydrogen bonds with the carboxylic acid group of MPA. The cocrystal MPA-ISO possesses remarkably improved solubility and dissolution rate, while two other cocrystals exhibit the opposite characteristics. The solids in the slurry with pH6.8 phosphate buffer and cocrystals remain as the incipient cocrystal after 24h. However, evidence of slight polymerization was shown in the slurry of pH6.8 phosphate buffer with MPA and MPA-ISO cocrystal. Copyright © 2017 Elsevier B.V. All rights reserved.

Gossip-based solutions for discrete rendezvous in populations of communicating agents.

PubMed

Hollander, Christopher D; Wu, Annie S

2014-01-01

The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm.

Gossip-Based Solutions for Discrete Rendezvous in Populations of Communicating Agents

PubMed Central

Hollander, Christopher D.; Wu, Annie S.

2014-01-01

The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm. PMID:25397882

Aggregation and Particle Formation of Therapeutic Proteins in Contact With a Novel Fluoropolymer Surface Versus Siliconized Surfaces: Effects of Agitation in Vials and in Prefilled Syringes.

PubMed

Teska, Brandon M; Brake, Jeffrey M; Tronto, Gregory S; Carpenter, John F

2016-07-01

We examined the effects of an accelerated agitation protocol on 2 protein therapeutics, intravenous immunoglobulin (IVIG) and Avastin (bevacizumab), in contact with a novel fluoropolymer surface and more typical siliconized surfaces. The fluoropolymer surface provides "solid-phase" lubrication for the syringe plunger-obviating the need for silicone oil lubrication in prefilled syringes. We tested the 2 surfaces in a vial system and in prefilled glass syringes. We also examined the effects of 2 buffers, phosphate-buffered saline (PBS) and 0.2-M glycine, with and without the addition of polysorbate 20, on agitation-induced aggregation of IVIG. Aggregation was monitored by measuring subvisible particle formation and soluble protein loss. In both vials and syringes, protein particle formation was much lower during agitation with the fluoropolymer surface than with the siliconized surface. Also, particle formation was greater in PBS than in glycine buffer, an effect attributed to lower colloidal stability of IVIG in PBS. Polysorbate 20 in the formulation greatly inhibited protein particle formation. Overall, the fluoropolymer plunger surface in an unsiliconized glass barrel was demonstrated to be a viable solution for eliminating silicone oil droplets from prefilled syringe formulations and providing a consistent system for rationale formulation development and simplified particle analysis. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Ozone and photocatalytic processes to remove the antibiotic sulfamethoxazole from water.

PubMed

Beltrán, Fernando J; Aguinaco, Almudena; García-Araya, Juan F; Oropesa, Ana

2008-08-01

In this study, water containing the pharmaceutical compound sulfamethoxazole (SMT) was subjected to the various treatments of different oxidation processes involving ozonation, and photolysis and catalysis under different experimental conditions. Removal rates of SMT and total organic carbon (TOC), from experiments of simple UVA radiation, ozonation (O(3)), catalytic ozonation (O(3)/TiO(2)), ozone photolysis (O(3)/UVA), photocatalytic oxidation (O(2)/TiO(2)/UVA) and photocatalytic ozonation (O(3)/UVA/TiO(2)), have been compared. Photocatalytic ozonation leads to the highest SMT removal rate (pH 7 in buffered systems, complete removal is achieved in less than 5min) and total organic carbon (in unbuffered systems, with initial pH=4, 93% TOC removal is reached). Also, lowest ozone consumption per TOC removed and toxicity was achieved with the O(3)/UVA/TiO(2) process. Direct ozone and free radical reactions were found to be the principal mechanisms for SMT and TOC removal, respectively. In photocatalytic ozonation, with buffered (pH 7) aqueous solutions phosphates (buffering salts) and accumulation of bicarbonate scavengers inhibit the reactions completely on the TiO(2) surface. As a consequence, TOC removal diminishes. In all cases, hydrogen peroxide plays a key role in TOC mineralization. According to the results obtained in this work the use of photocatalytic ozonation is recommended to achieve a high mineralization degree of water containing SMT type compounds.

Calorimetric and Diffractometric Evidence for the Sequential Crystallization of Buffer Components and the Consequential pH Swing in Frozen Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj

2010-06-22

Sequential crystallization of succinate buffer components in the frozen solution has been studied by differential scanning calorimetry and X-ray diffractometry (both laboratory and synchrotron sources). The consequential pH shifts were monitored using a low-temperature electrode. When a solution buffered to pH < pK{sub a2} was cooled from room temperature (RT), the freeze-concentrate pH first increased and then decreased. This was attributed to the sequential crystallization of succinic acid, monosodium succinate, and finally disodium succinate. When buffered to pH > pK{sub a2}, the freeze-concentrate pH first decreased and then increased due to the sequential crystallization of the basic (disodium succinate) followedmore » by the acidic (monosodium succinate and succinic acid) buffer components. XRD provided direct evidence of the crystallization events in the frozen buffer solutions, including the formation of disodium succinate hexahydrate [Na{sub 2}(CH{sub 2}COO){sub 2} {center_dot} 6H{sub 2}O]. When the frozen solution was warmed in a differential scanning calorimeter, multiple endotherms attributable to the melting of buffer components and ice were observed. When the frozen solutions were dried under reduced pressure, ice sublimation was followed by dehydration of the crystalline hexahydrate to a poorly crystalline anhydrate. However, crystalline succinic acid and monosodium succinate were retained in the final lyophiles. The pH and the buffer salt concentration of the prelyo solution influenced the crystalline salt content in the final lyophile. The direction and magnitude of the pH shift in the frozen solution depended on both the initial pH and the buffer concentration. In light of the pH-sensitive nature of a significant fraction of pharmaceuticals (especially proteins), extreme care is needed in both the buffer selection and its concentration.« less

Assessing the influence of media composition and ionic strength on drug release from commercial immediate-release and enteric-coated aspirin tablets.

PubMed

Karkossa, Frank; Klein, Sandra

2017-10-01

The objective of this test series was to elucidate the importance of selecting the right media composition for a biopredictive in-vitro dissolution screening of enteric-coated dosage forms. Drug release from immediate-release (IR) and enteric-coated (EC) aspirin formulations was assessed in phosphate-based and bicarbonate-based media with different pH, electrolyte composition and ionic strength. Drug release from aspirin IR tablets was unaffected by media composition. In contrast, drug release from EC aspirin formulations was affected by buffer species and ionic strength. In all media, drug release increased with increasing ionic strength, but in bicarbonate-based buffers was delayed when compared with that in phosphate-based buffers. Interestingly, the cation species in the dissolution medium had also a clear impact on drug release. Drug release profiles obtained in Blank CarbSIF, a new medium simulating pH and average ionic composition of small intestinal fluid, were different from those obtained in all other buffer compositions studied. Results from this study in which the impact of various media parameters on drug release of EC aspirin formulations was systematically screened clearly show that when developing predictive dissolution tests, it is important to simulate the ionic composition of intraluminal fluids as closely as possible. © 2017 Royal Pharmaceutical Society.

Inhibition of Protein Carbamylation in Urea Solution Using Ammonium Containing Buffers

PubMed Central

Sun, Shisheng; Zhou, Jian-Ying; Yang, Weiming; Zhang, Hui

2013-01-01

Urea solution is one of the most commonly employed protein denaturants for protease digestion in proteomic studies. However, it has long been recognized that urea solution can cause carbamylation at the N-termini of proteins/peptides and at the side chain amino groups of lysine and arginine residues. Protein/peptide carbamylation blocks protease digestion and affects protein identification and quantification in mass spectrometry analysis by blocking peptide amino groups from isotopic/isobaric labeling and changing peptide charge states, retention times and masses. In addition, protein carbamylation during sample preparation makes it difficult to study in vivo protein carbamylation. In this study, we compared the peptide carbamylation in urea solutions of different buffers and found that ammonium containing buffers were the most effective buffers to inhibit protein carbamylation in urea solution. The possible mechanism of carbamylation inhibition by ammonium containing buffers is discussed, and a revised procedure for the protease digestion of proteins in urea and ammonium containing buffers was developed to facilitate its application in proteomic research. PMID:24161613

Buffers more than buffering agent: introducing a new class of stabilizers for the protein BSA.

PubMed

Gupta, Bhupender S; Taha, Mohamed; Lee, Ming-Jer

2015-01-14

In this study, we have analyzed the influence of four biological buffers on the thermal stability of bovine serum albumin (BSA) using dynamic light scattering (DLS). The investigated buffers include 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), 4-(2-hydroxyethyl)-1-piperazine-propanesulfonic acid (EPPS), 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid sodium salt (HEPES-Na), and 4-morpholinepropanesulfonic acid sodium salt (MOPS-Na). These buffers behave as a potential stabilizer for the native structure of BSA against thermal denaturation. The stabilization tendency follows the order of MOPS-Na > HEPES-Na > HEPES ≫ EPPS. To obtain an insight into the role of hydration layers and peptide backbone in the stabilization of BSA by these buffers, we have also explored the phase transition of a thermoresponsive polymer, poly(N-isopropylacrylamide (PNIPAM)), a model compound for protein, in aqueous solutions of HEPES, EPPS, HEPES-Na, and MOPS-Na buffers at different concentrations. It was found that the lower critical solution temperatures (LCST) of PNIPAM in the aqueous buffer solutions substantially decrease with increase in buffer concentration. The mechanism of interactions between these buffers and protein BSA was probed by various techniques, including UV-visible, fluorescence, and FTIR. The results of this series of studies reveal that the interactions are mainly governed by the influence of the buffers on the hydration layers surrounding the protein. We have also explored the possible binding sites of BSA with these buffers using a molecular docking technique. Moreover, the activities of an industrially important enzyme α-chymotrypsin (α-CT) in 0.05 M, 0.5 M, and 1.0 M of HEPES, EPPS, HEPES-Na, and MOPS-Na buffer solutions were analyzed at pH = 8.0 and T = 25 °C. Interestingly, the activities of α-CT were found to be enhanced in the aqueous solutions of these investigated buffers. Based upon the Jones-Dole viscosity parameters, the kosmotropic or chaotropic behaviors of the investigated buffers at 25 °C have been examined.

Equilibrium water and solute uptake in silicone hydrogels.

PubMed

Liu, D E; Dursch, T J; Oh, Y; Bregante, D T; Chan, S Y; Radke, C J

2015-05-01

Equilibrium water content of and solute partitioning in silicone hydrogels (SiHys) are investigated using gravimetric analysis, fluorescence confocal laser-scanning microscopy (FCLSM), and back extraction with UV/Vis-absorption spectrophotometry. Synthesized silicone hydrogels consist of silicone monomer, hydrophilic monomer, cross-linking agent, and triblock-copolymer macromer used as an amphiphilic compatibilizer to prevent macrophase separation. In all cases, immiscibility of the silicone and hydrophilic polymers results in microphase-separated morphologies. To investigate solute uptake in each of the SiHy microphases, equilibrium partition coefficients are obtained for two hydrophilic solutes (i.e., theophylline and caffeine dissolved in aqueous phosphate-buffered saline) and two oleophilic solutes (i.e., Nile Red and Bodipy Green dissolved in silicone oil), respectively. Measured water contents and aqueous-solute partition coefficients increase linearly with increasing solvent-free hydrophilic-polymer volume fraction. Conversely, oleophilic-solute partition coefficients decrease linearly with rising solvent-free hydrophilic-polymer volume fraction (i.e., decreasing hydrophobic silicone-polymer fraction). We quantitatively predict equilibrium SiHy water and solute uptake assuming that water and aqueous solutes reside only in hydrophilic microdomains, whereas oleophilic solutes partition predominately into silicone microdomains. Predicted water contents and solute partition coefficients are in excellent agreement with experiment. Our new procedure permits a priori estimation of SiHy water contents and solute partition coefficients based solely on properties of silicone and hydrophilic homopolymer hydrogels, eliminating the need for further mixed-polymer-hydrogel experiments. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Influence of some mononucleotides and their corresponding nucleosides on the metabolism of carbohydrates in the isolated rat diaphragm muscle

PubMed Central

Beloff-Chain, Anne; Betto, P.; Bleszynski, W.; Catanzaro, Raffaella; Chain, E. B.; Dmitrovskii, A. A.; Longinotti, L.; Pocchiari, F.

1965-01-01

1. The influence of ATP on glucose metabolism was studied in the isolated rat diaphragm; it was shown that ATP increases the oxidation of glucose and the aerobic conversion of glucose into lactate, whereas it decreases glycogen synthesis. There was no influence of ATP on the anaerobic formation of lactate from glucose. 2. A maximum effect of ATP on the oxidation of glucose (about 160% increase) was obtained in the presence of 10mm-ATP; in the presence of 2mm-ATP the effect was about 65%, and was approximately constant from 10 to 90min. incubation period. 3. In a phosphate-free tris-buffered medium the oxidation of glucose was considerably decreased, but the percentage stimulation by ATP was about the same as in a phosphate-buffered medium. 4. ATP was shown to increase the oxidation of fructose, glucose 6-phosphate, glucose 1-phosphate, fructose 1,6-diphosphate and, to a much smaller extent, pyruvate. 5. ADP stimulated the oxidation of glucose to the same extent as ATP at a concentration of 2mm and the effect with AMP was only slightly less; IMP and adenosine had only a small stimulatory effect at this concentration, whereas inosine had no effect. PMID:16749165

Final report of the key comparison APMP.QM-K91: APMP comparison on pH measurement of phthalate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Asakai, Toshiaki; Maksimov, Igor; Suzuki, Toshihiro; Miura, Tsutomu; Ketrin, Rosi; Nuryatini; Thanh, Ngo Huy; Truong Chinh, Nguyen; Vospelova, Alena; Bastkowski, Frank; Sander, Beatrice; Matzke, Jessica; Prokunin, Sergey; Frolov, Dmitry; Aprelev, Alexey; Dobrovolskiy, Vladimir; Uysal, Emrah; Liv, Lokman; Velina Lara-Manzano, Judith; Montero-Ruiz, Jazmin; Ortiz-Aparicio, JosÉ Luis; Ticona Canaza, Galia; Anuar Mohd Amin, Khirul; Abd Kadir, Haslina; Bakovets, Nickolay; Wong, Siu-Kay; Lam, Wai-Hing

2017-01-01

The APMP.QM-K91 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phthalate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan at the APMP-TCQM meeting held September 22-23, 2014. After approval by TCQM, the comparison has been conducted by NMIJ. The comparison is a key comparison following CCQM-K91. The comparison material was a phthalate buffer of pH around 4.0 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the third APMP key comparison on pH measurement and the fifth APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004, APMP.QM-P09 (a phthalate buffer) in 2006, APMP.QM-K9/APMP.QM-P16 (a phosphate buffer) in 2010-2011 and APMP.QM-K19/APMP.QM-P25 (a borate buffer) in 2013-2014. The results can be used further by any participant to support its CMC claim at least for a phthalate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Effect of in vitro degradation of poly(D,L-lactide)/beta-tricalcium composite on its shape-memory properties.

PubMed

Zheng, Xiaotong; Zhou, Shaobing; Yu, Xiongjun; Li, Xiaohong; Feng, Bo; Qu, Shuxin; Weng, Jie

2008-07-01

The in vitro degradation characteristic and shape-memory properties of poly(D,L-lactide) (PDLLA)/beta-tricalcium phosphate (beta-TCP) composites were investigated because of their wide application in biomedical fields. In this article, PDLLA and crystalline beta-TCP were compounded and interesting shape-memory behaviors of the composite were first investigated. Then, in vitro degradation of the PDLLA/beta-TCP composites with weight ratios of 1:1, 2:1, and 3:1 was performed in phosphate buffer saline solution (PBS) (154 mM, pH 7.4) at 37 degrees C. The effect of in vitro degradation time for PDLLA/beta-TCP composites on shape-memory properties was studied by scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The changes of structural morphology, glass transition temperature (T(g)), molecular weight, and weight loss of composites matrix and pH change of degradation medium indicated that shape-memory effects at different degradation time were nonlinearly influenced because of the breaking down of polymer chain and the formation of degradation products. Furthermore, the results from XRD and FTIR implied that the degradation products, for example, hydroxyapatite (HA), calcium hydrogen phosphate (CaHPO(4)), and calcium pyrophosphate (Ca(2)P(2)O(7)) phases also had some effects on shape-memory properties during the degradation. 2007 Wiley Periodicals, Inc.

Host plasma proteins on the surface of pathogenic Trichomonas vaginalis.

PubMed

Peterson, K M; Alderete, J F

1982-08-01

Sodium dodecyl sulfate-gel electrophoresis and fluorography and fluorography technology revealed that pathogenic Trichomonas vaginalis was able to acquire numerous loosely associated plasma proteins during incubation in normal human plasma. These proteins were readily removed by repeated washing of the parasite in phosphate-buffered saline. Plasma proteins avidly bound to the surface of T. vaginalis were also detected using a highly sensitive and specific agglutination assay with protein A-bearing Staphylococcus aureus pretreated with monospecific antiserum directed against individual human serum proteins. These avidly associated plasma proteins could not be removed by repeated washing in phosphate-buffered saline or by treatment of washed, live organisms with surface-modifying reagents such as trypsin and periodate. A combined radioimmunoprecipitation-gel electrophoresis-fluorography methodology indicated that parasite biosynthesis of hostlike macromolecules was not responsible for the observed agglutination and reinforced the idea of trichosomal acquisition of plasma components. Finally, incubation of trichomonads with plasma in various buffers at different pH values did not alter the agglutination patterns. These and other data suggest that specific membrane sites trichomonal binding of host proteins. The biological significance of our results is discussed.

Iodine susceptibility of pseudomonads grown attached to stainless steel surfaces

NASA Technical Reports Server (NTRS)

Pyle, B. H.; McFeters, G. A.

1990-01-01

Pseudomonads were adapted to grow in phosphate-buffered water and on stainless steel surfaces to study the iodine sensitivity of attached and planktonic cells. Cultures adapted to low nutrient growth were incubated at room temperature in a circulating reactor system with stainless steel coupons to allow biofilm formation on the metal surfaces. In some experiments, the reactor was partially emptied and refilled with buffer at each sampling time to simulate a "fill-and-draw" water system. Biofilms of attached bacteria, resuspended biofilm bacteria, and reactor suspension, were exposed to 1 mg l-1 iodine for 2 min. Attached bacterial populations which established on coupons within 3 to 5 days displayed a significant increase in resistance to iodine. Increased resistance was also observed for resuspended cells from the biofilm and planktonic bacteria in the system suspension. Generally, intact biofilms and resuspended biofilm cells were most resistant, followed by planktonic bacteria and phosphate buffer cultures. Thus, biofilm formation on stainless steel surfaces within water systems can result in significantly increased disinfection resistance of commonly-occurring water-borne bacteria that may enhance their ability to colonise water treatment and distribution systems.

Predicting the crystallization propensity of carboxylic acid buffers in frozen systems--relevance to freeze-drying.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-04-01

Selective crystallization of buffer components in frozen solutions is known to cause pronounced pH shifts. Our objective was to study the crystallization behavior and the consequent pH shift in frozen aqueous carboxylic acid buffers. Aqueous carboxylic acid buffers were cooled to -25°C and the pH of the solution was measured as a function of temperature. The thermal behavior of solutions during freezing and thawing was investigated by differential scanning calorimetry. The crystallized phases in frozen solution were identified by X-ray diffractometry. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartarate systems, at initial pH

Immobilization of tyrosinase in carboxylic and carbonyl group-modified MWNT electrode and its application for sensing phenolics in red wines.

PubMed

Kim, Kyo-Il; Lee, Jae-Chan; Robards, Kevin; Choi, Seong-Ho

2010-06-01

Tyrosinase-immobilized biosensor was fabricated based on PAAc-g-MWNT and PMAn-g-MWNT, respectively. The poly(acrylic acid)-grafted multi-wall carbon nanotubes, PAAc-g-MWNT, and poly(maleic anhydride)-grafted multi-wall carbon nanotube, PMAn-g-MWNT, were prepared by radiation-induced graft polymerization of acrylic acid (AAc) and maleic anhydride (MAn) on the surface of MWNT. The biosensor was prepared on ITO glass electrode by coating of chitosan solution with tyrosinase-immobilized PAAc-g-MWNT and PMAn-g-MWNT, respectively. The sensing ranges of the tyrosinase-immobilized biosensor based on PAAc-g-MWNT and PMAn were in the range of 0.2-0.9 mM concentration and in the range of 0.1-0.5 mM for phenol in phosphate buffer solution, respectively. Optimal pH and temperature conditions for sensing various phenolic compounds with tyrosinase-immobilized biosensor were determined. Total phenolic content for three commercial red wines on tyrosinase-immobilized biosensor were also determined.

Preparation of cellulose based microspheres by combining spray coagulating with spray drying.

PubMed

Wang, Qiao; Fu, Aiping; Li, Hongliang; Liu, Jingquan; Guo, Peizhi; Zhao, Xiu Song; Xia, Lin Hua

2014-10-13

Porous microspheres of regenerated cellulose with size in range of 1-2 μm and composite microspheres of chitosan coated cellulose with size of 1-3 μm were obtained through a two-step spray-assisted approach. The spray coagulating process must combine with a spray drying step to guarantee the formation of stable microspheres of cellulose. This approach exhibits the following two main virtues. First, the preparation was performed using aqueous solution of cellulose as precursor in the absence of organic solvent and surfactant; Second, neither crosslinking agent nor separated crosslinking process was required for formation of stable microspheres. Moreover, the spray drying step also provided us with the chance to encapsulate guests into the resultant cellulose microspheres. The potential application of the cellulose microspheres acting as drug delivery vector has been studied in two PBS (phosphate-buffered saline) solution with pH values at 4.0 and 7.4 to mimic the environments of stomach and intestine, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis, characterization, and electrochemical behavior of Au@Pd core shell nanoparticles

NASA Astrophysics Data System (ADS)

Wicaksono, W. P.; Ivandini, T. A.

2017-04-01

Au@Pd core shell nanoparticles (Au@Pd CSNPs) were successfully synthesized using a seed-mediated growth method. Firstly, a pale pink gold seed solution was used to produce a pale purple gold nanoparticles (AuNPs) core solution. Then, three series of Pd shell thickness using 20μ, 100 μL, and 500 μL of PdCl2 produced purple, brown, and deep brown of Au@Pd CSNPs respectively. A strong absorbance UV-Visible spectrum with peaks at 285 nm and 535 nm was identified for AuNPs formation. The disappearance of the peak at 535 nm was indicated the Au@Pd CSNPs formation. The electrochemical properties were examined in phosphate buffer pH 7 using cyclic voltammetry technique with boron-doped diamond (BDD) as working electrode showed a couple oxidation and reduction peak of gold at 0.67 V and at 0.33 V, respectively. The Au@Pd CNPs will be used for modification of BDD electrodes.

Plasma-induced graft-polymerization of polyethylene glycol acrylate on polypropylene substrates

NASA Astrophysics Data System (ADS)

Zanini, S.; Orlandi, M.; Colombo, C.; Grimoldi, E.; Riccardi, C.

2009-08-01

A detailed study of argon plasma-induced graft-polymerization of polyethylene glycol acrylate (PEGA) on polypropylene (PP) substrates (membranes and films) is presented. The process consists of four steps: (a) plasma pre-activation of the PP substrates; (b) immersion in a PEGA solution; (c) argon plasma-induced graft-polymerization; (d) washing and drying of the samples. Influence of the solution and plasma parameters on the process efficiency evaluated in terms of amount of grafted polymer, coverage uniformity and substrates wettability, are investigated. The plasma-induced graft-polymerization of PEGA is then followed by sample weighting, water droplet adsorption time and contact angle measurements, attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analyses. The stability of the obtained thin films was evaluated in water and in phosphate buffer saline (PBS) at 37 °C. Results clearly indicates that plasma-induced graft-polymerization of PEGA is a practical methodology for anti-fouling surface modification of materials.

Effect of pH adjustment, homogenization and diafiltration on physicochemical, reconstitution, functional and rheological properties of medium protein milk protein concentrates (MPC70).

PubMed

Meena, Ganga Sahay; Singh, Ashish Kumar; Gupta, Vijay Kumar; Borad, Sanket; Arora, Sumit; Tomar, Sudhir Kumar

2018-04-01

Poor solubility is the major limiting factor in commercial applications of milk protein concentrates (MPC) powders. Retentate treatments such as pH adjustment using disodium phosphate (Na 2 HPO 4 ), also responsible for calcium chelation with homogenization and; its diafiltration with 150 mM NaCl solution were hypothesized to improve the functional properties of treated MPC70 powders. These treatments significantly improved the solubility, heat stability, water binding, dispersibility, bulk density, flowability, buffer index, foaming and emulsifying capacity of treated powders over control. Rheological behaviour of reconstituted MPC solutions was best explained by Herschel Bulkley model. Compared to rough, large globular structures with dents in control; majorly intact, separate, smaller particles of smooth surface, without any aggregation were observed in SEM micrograph of treated powders. Applied treatments are easy, cost-effective and capable to improve functional properties of treated powders that could replace control MPC70 powder in various food applications where protein functionality is of prime importance.

Determination of fluorine and chlorine in geological materials by induction furnace pyrohydrolysis and standard-addition ion-selective electrode measurement.

PubMed

Rice, T D

1988-03-01

Fluorine and chlorine in geological materials are volatilized by pyrohydrolysis at about 1150 degrees in a stream of oxygen (1000 ml/min) plus steam in an induction furnace. The catalyst is a 7:2:1 mixture of silica gel, tungstic oxide and potassium dihydrogen phosphate. The sample/catalyst mixture is pyrohydrolysed in a re-usable alumina crucible (already containing four drops of 1 + 3 phosphoric acid) inserted in a silica-enclosed graphite crucible. The absorption solution is buffered at pH 6.5 and spiked with 1.6 mug of fluoride and 16 mug of chloride per g of solution, to ensure rapid and linear electrode response during subsequent standard-addition measurement. The simple plastic absorption vessel has 99.5% efficiency. The 3s limits of detection are 5-10 mug/g and 40-100 mug/g for fluorine and chlorine respectively. The procedure is unsuitable for determining chlorine in coal.

Adenine phosphoribosyltransferase from Sulfolobus solfataricus is an enzyme with unusual kinetic properties and a crystal structure that suggests it evolved from a 6-oxopurine phosphoribosyltransferase.

PubMed

Jensen, Kaj Frank; Hansen, Michael Riis; Jensen, Kristine Steen; Christoffersen, Stig; Poulsen, Jens-Christian Navarro; Mølgaard, Anne; Kadziola, Anders

2015-04-14

The adenine phosphoribosyltransferase (APRTase) encoded by the open reading frame SSO2342 of Sulfolobus solfataricus P2 was subjected to crystallographic, kinetic, and ligand binding analyses. The enzyme forms dimers in solution and in the crystals, and binds one molecule of the reactants 5-phosphoribosyl-α-1-pyrophosphate (PRPP) and adenine or the product adenosine monophosphate (AMP) or the inhibitor adenosine diphosphate (ADP) in each active site. The individual subunit adopts an overall structure that resembles a 6-oxopurine phosphoribosyltransferase (PRTase) more than known APRTases implying that APRT functionality in Crenarchaeotae has its evolutionary origin in this family of PRTases. Only the N-terminal two-thirds of the polypeptide chain folds as a traditional type I PRTase with a five-stranded β-sheet surrounded by helices. The C-terminal third adopts an unusual three-helix bundle structure that together with the nucleobase-binding loop undergoes a conformational change upon binding of adenine and phosphate resulting in a slight contraction of the active site. The inhibitor ADP binds like the product AMP with both the α- and β-phosphates occupying the 5'-phosphoribosyl binding site. The enzyme shows activity over a wide pH range, and the kinetic and ligand binding properties depend on both pH and the presence/absence of phosphate in the buffers. A slow hydrolysis of PRPP to ribose 5-phosphate and pyrophosphate, catalyzed by the enzyme, may be facilitated by elements in the C-terminal three-helix bundle part of the protein.

Electrodialysis operation with buffer solution

DOEpatents

Hryn, John N [Naperville, IL; Daniels, Edward J [Orland Park, IL; Krumdick, Greg K [Crete, IL

2009-12-15

A new method for improving the efficiency of electrodialysis (ED) cells and stacks, in particular those used in chemical synthesis. The process entails adding a buffer solution to the stack for subsequent depletion in the stack during electrolysis. The buffer solution is regenerated continuously after depletion. This buffer process serves to control the hydrogen ion or hydroxide ion concentration so as to protect the active sites of electrodialysis membranes. The process enables electrodialysis processing options for products that are sensitive to pH changes.

Removal of phosphate from aqueous solutions and sewage using natural and surface modified coir pith.

PubMed

Krishnan, K Anoop; Haridas, Ajit

2008-04-01

Iron impregnated coir pith (CP-Fe-I) can be effectively used for the removal of phosphate from aqueous streams and sewage. Iron impregnation on natural coir pith was carried out by drop by drop addition method. The effect of various factors such as pH, initial concentration of phosphate, contact time and adsorbent dose on phosphate adsorption was studied by batch technique. The pH at 3.0 favored the maximum adsorption of phosphate from aqueous solutions. The effect of pH on phosphate adsorption was explained by pH(zpc), phosphate speciation in solution and affinity of anions towards the adsorbent sites. A comparative study of the adsorption of phosphate using CP-Fe-I and CP (coir pith) was made and results show that the former one is five to six times more effective than the latter. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Adsorption followed Langmuir isotherm model. Column studies were conducted to examine the utility of the investigated adsorbent for the removal of phosphate from continuously flowing aqueous solutions.

Increased degradation rate of nitrososureas in media containing carbonate.

PubMed

Seidegård, Janeric; Grönquist, Lena; Tuvesson, Helen; Gunnarsson, Per-Olov

2009-01-01

The stability of two nitrosoureas, tauromustine and lomustine, has been investigated in different media and buffers. All media tested, except Leibovitz's L-15 medium, significantly increased the degradation rate of the investigated nitrosoureas at pH 7.4. Sodium bicarbonate seems to be the cause of the observed increase of the degradation rate, since it provides the main buffering capacity of all the media except for Leibovitz's L-15 medium, which is based on phosphate buffer. Other ingredients in the media, such as amino acids, vitamins, and inorganic salts, or the ionic strength of a buffer, did not have any major effect on the degradation rate of the nitrosoureas. These results suggest that media containing carbonated buffer should be avoided when the anti-tumor effect of nitrosoureas is to be investigated in different cell cultures.

Functional Analysis of Human NF1 in Drosophila

DTIC Science & Technology

2007-01-01

adjusted to 1 mg/ml. Fifty microlitres of 2 assay buffer (50 mM Tris– acetate buffer at pH 7.5, 20 mM MgCl2, 2 mM dithiothreitol, 10 mM creatine phosphate...200 units/ml creatinine kinase, 0.1 mM cAMP at pH 7.5, 0.2 mg/ml bovine serum albumin, 0.02 mg/ml aprotinin, 0.02 mg/ml pepstatin and fresh 0.2 mg

Enhanced Biocompatibility of Porous Nitinol

PubMed Central

Munroe, Norman; Pulletikurthi, Chandan; Haider, Waseem

2009-01-01

Porous Nitinol (PNT) has found vast applications in the medical industry as interbody fusion devices, synthetic bone grafts, etc. However, the tendency of the PNT to corrode is anticipated to be greater as compared to solid nitinol since there is a larger surface area in contact with body fluids. In such cases, surface preparation is known to play a major role in a material’s biocompatibility. In an effort to check the effect of surface treatments on the in vitro corrosion properties of PNT, in this investigation, they were subjected to different surface treatments such as boiling in water, dry heating, and passivation. The localized corrosion resistance of alloys before and after each treatment was evaluated in phosphate buffer saline solution (PBS) using cyclic polarization tests in accordance with ASTM F 2129-08. PMID:19956797

Enhanced Biocompatibility of Porous Nitinol

NASA Astrophysics Data System (ADS)

Munroe, Norman; Pulletikurthi, Chandan; Haider, Waseem

2009-08-01

Porous Nitinol (PNT) has found vast applications in the medical industry as interbody fusion devices, synthetic bone grafts, etc. However, the tendency of the PNT to corrode is anticipated to be greater as compared to solid nitinol since there is a larger surface area in contact with body fluids. In such cases, surface preparation is known to play a major role in a material’s biocompatibility. In an effort to check the effect of surface treatments on the in vitro corrosion properties of PNT, in this investigation, they were subjected to different surface treatments such as boiling in water, dry heating, and passivation. The localized corrosion resistance of alloys before and after each treatment was evaluated in phosphate buffer saline solution (PBS) using cyclic polarization tests in accordance with ASTM F 2129-08.

Antihistamine effect on synaptosomal uptake of serotonin, norepinephrine and dopamine

NASA Technical Reports Server (NTRS)

Brown, P. A.; Vernikos, J.

1980-01-01

A study on the effects of five H1 and H2 antihistamines on the synaptosomal uptake of serotonin (5HT), norepinephrine (NE), and dopamine (DA) is presented. Brain homogenates from female rats were incubated in Krebs-Ringer phosphate buffer solution in the presence of one of three radioactive neurotransmitters, and one of the five antihistamines. Low concentrations of pyrilamine competitively inhibited 5HT uptake, had little effect on NE uptake, and no effect on DA uptake. Promethazine, diphenhydramine, metiamide, and cimetidine had no effect on 5HT or DA uptake at the same concentration. Diphenhydramine had a small inhibitory effect on NE uptake. It is concluded that pyrilamine is a selective and potent competitive inhibitor of 5HT uptake at concentrations between .05 and .5 micromolars.

Preparation of glucose sensors using gold nanoparticles modified diamond electrode

NASA Astrophysics Data System (ADS)

Fachrurrazie; Ivandini, T. A.; Wibowo, W.

2017-04-01

A glucose sensor was successfully developed by immobilizing glucose oxidase (GOx) at boron-doped diamond (BDD) electrodes. Prior to GOx immobilization, the BDD was modified with gold nanoparticles (AuNPs). To immobilize AuNPs, the gold surface was modified to nitrogen termination. The characterization of the electrode surface was performed using an X-ray photoelectron spectroscopy and a scanning electron microscope, while the electrochemical properties of the enzyme electrode were characterized using cyclic voltammetry. Cyclic voltammograms of the prepared electrode for D-glucose in phosphate buffer solution pH 7 showed a new reduction peak at +0.16 V. The currents of the peak were linear in the concentration range of 0.1 M to 0.9 M, indicated that the GOx-AuNP-BDD can be applied for electrochemical glucose detection.

Detection of DNA hybridization using graphene-coated black phosphorus surface plasmon resonance sensor

NASA Astrophysics Data System (ADS)

Pal, Sarika; Verma, Alka; Raikwar, S.; Prajapati, Y. K.; Saini, J. P.

2018-05-01

In this paper, graphene-coated black phosphorus at the metal surface for the detection of DNA hybridization event is numerically demonstrated. The strategy consists of placing the sensing medium on top of black phosphorus-graphene-coated SPR which interfaces with phosphate-buffered saline solution carrying single-stranded DNA. Upon hybridization with its complementary DNA, desorption of the nanostructures takes place and thus enables the sensitive detection of the DNA hybridization event. The proposed sensor exhibits a sensitivity (125 ο/RIU), detection accuracy (0.95) and quality factor (13.62 RIU-1) for complementary DNA. In comparison with other reported papers, our suggested sensor provides much better performance. Thus, this label-free DNA detection platform should spur off new interest towards the use of black phosphorus-graphene-coated SPR interfaces.

Biomedical silver-109m isotope generator

DOEpatents

Wanek, Philip M.; Steinkruger, Frederick J.; Moody, David C.

1987-01-01

A method, composition of matter, and apparatus for producing substantially pure Ag-109m for use in biomedical imaging techniques. Cd-109, which decays with a half-life of 453 days to Ag-109m is loaded onto an ion exchange column consisting of particulate tin phosphate. After secular equilibrium is reached in about ten minutes, Ag-109m may be selectively eluted from the column by means of a physiologically acceptable aqueous buffered eluent solution of sodium thiosulfate, and either ascorbic acid or dextrose. The breakthrough of toxic Cd-109 is on the order of 1.times.10.sup.-7, which is sufficiently low to permit administration of the Ag-109m-containing eluate, with but a minor pH adjustment, directly to a human patient within a matter of seconds.

Biomedical silver-109m isotope generator

DOEpatents

Wanek, P.M.; Steinkruger, F.J.; Moody, D.C.

1985-03-05

A method, composition of matter, and apparatus for producing substantially pure Ag-109m for use in biomedical imaging techniques. Cd-109, which decays with a half-life of 453 days to Ag-109m, is loaded onto an ion exchange column consisting of particulate tin phosphate. After secular equilibrium is reached in about ten minutes, Ag-109m may be selectively eluted from the column by means of a physiologically acceptable aqueous buffered eluent solution of sodium thiosulfate, and either ascorbic acid or dextrose. The breakthrough of toxic Cd-109 is on the order of 1 x 10-7, which is sufficiently low to permit administration of the Ag-109m-containing eluate, with but a minor pH adjustment, directly to a human patient within a matter of seconds. 1 fig.

Capillary zone electrophorsis for the analysis of naturally occurring 2-hydroxycitric acids and their lactones.

PubMed

Abhijith, B L; Mohan, Moolya; Joseph, David; Haleema, Simimole; Aboul-Enein, Hassan Y; Ibnusaud, Ibrahim

2017-08-01

A simple capillary zone electrophoresis method with direct ultraviolet detection has been developed for the analysis of naturally occurring diastereomeric 2-hydroxycitric acid lactones. Using 50 mM sodium phosphate buffer of pH 7, a baseline resolution R s > 3.0 was observed for all organic acids selected for the present study. This method was employed for the quantitative determination of title acids present in the plant sources namely Garcinia cambogia fruit rinds and Hibiscus sabdariffa calyx. Conversion of 2-hydroxycitric acids to their lactones on heating the above plant sources is deliberated. The Hydrolysis of hydroxycitric acid lactones in aqueous solution is reported for the first time. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitive Voltammetric Determination of Natural Flavonoid Quercetin on a Disposable Graphite Lead

PubMed Central

Vu, Dai Long; Žabčíková, Simona; Ertek, Bensu; Dilgin, Yusuf

2015-01-01

Summary In this paper, a pencil graphite electrode was pretreated using chronoamperometry technique in phosphate buffer solution (pH=7.0) for sensitive determination of quercetin. Oxidation of quercetin was investigated using pretreated pencil graphite electrode and anodic stripping differential pulse voltammetry. Under optimal conditions, the anodic current of quercetin exhibited linear response to its concentration in the range from 0.001 to 1.5 µmol/L with the limit of detection of 0.3·10–3 µmol/L. The proposed method was successfully applied for the determination of quercetin in cranberry and blackcurrant juices with recovery rate from 93.2 to 94.7%. Solid-phase extraction was found to be necessary prior to voltammetric determination of quercetin in fruit juice samples using pretreated pencil graphite electrode. PMID:27904372

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of methylene blue active substances by spectrophotometry

USGS Publications Warehouse

Burkhardt, Mark R.; Cinotto, Pete J.; Frahm, Galen W.; Woodworth, Mark T.; Pritt, Jeffrey W.

1995-01-01

A method for the determination of methylene blue active substances in whole-water samples by liquid-liquid extraction and spectrophotometric detection is described. Sulfate and sulfonate-based surfectants are reacted with methylene blue to form a blue-colored complex. The complex is extracted into chloroform, back-washed with an acidified phosphate-based buffer solution, and measured against external standards with a probe spectrophotometer. The method detection limt for routine analysis is 0.02 milligram per liter. The precision is plus/minus 10 percent relative standard deviation. The positive bias from nitrate and chloride and U.S. Geological Survey method O-3111-83 for methylene blue active substances is minized by adding a back-washing step.

Decomposition of L-valine under nonthermal dielectric barrier discharge plasma.

PubMed

Li, Yingying; Kojtari, Arben; Friedman, Gary; Brooks, Ari D; Fridman, Alex; Ji, Hai-Feng

2014-02-13

L-Valine solutions in water and phosphate buffer were treated with nonthermal plasma generated by using a dielectric barrier discharge (DBD) device and the products generated after plasma treatments were characterized by (1)H NMR and GC-MS. Our results demonstrate that L-valine is decomposed to acetone, formic acid, acetic acid, threo-methylaspartic acid, erythro-methlyaspartic acid, and pyruvic acid after direct exposure to DBD plasma. The concentrations of these compounds are time-dependent with plasma treatment. The mechanisms of L-valine under the DBD plasma are also proposed in this study. Acetone, pyruvic acid, and organic radicals (•)CHO, CH3COCH2OO(•) (acetonylperoxy), and CH3COC(OH)2OO(•) (1,1-dihydroxypropan-2-one peroxy) may be the determining chemicals in DNA damage.

Microbial solubilization of phosphate

DOEpatents

Rogers, R.D.; Wolfram, J.H.

1993-10-26

A process is provided for solubilizing phosphate from phosphate containing ore by treatment with microorganisms which comprises forming an aqueous mixture of phosphate ore, microorganisms operable for solubilizing phosphate from the phosphate ore and maintaining the aqueous mixture for a period of time and under conditions operable to effect the microbial solubilization process. An aqueous solution containing soluble phosphorus can be separated from the reacted mixture by precipitation, solvent extraction, selective membrane, exchange resin or gravity methods to recover phosphate from the aqueous solution. 6 figures.

Microbial solubilization of phosphate

DOEpatents

Rogers, Robert D.; Wolfram, James H.

1993-01-01

A process is provided for solubilizing phosphate from phosphate containing ore by treatment with microorganisms which comprises forming an aqueous mixture of phosphate ore, microorganisms operable for solubilizing phosphate from the phosphate ore and maintaining the aqueous mixture for a period of time and under conditions operable to effect the microbial solubilization process. An aqueous solution containing soluble phosphorous can be separated from the reacted mixture by precipitation, solvent extraction, selective membrane, exchange resin or gravity methods to recover phosphate from the aqueous solution.

A self-powered kinesin-microtubule system for smart cargo delivery

NASA Astrophysics Data System (ADS)

Jia, Yi; Dong, Weiguang; Feng, Xiyun; Li, Jieling; Li, Junbai

2014-11-01

A smart self-powered cargo delivery system that is composed of creatine phosphate kinase (CPK) microspheres, kinesins and microtubules is demonstrated. The CPK microsphere not only acts as an ATP generation and buffering system, but also as a carrier for cargo transport, thus realizing the easy loading and self-powered delivery of cargos at the same time.A smart self-powered cargo delivery system that is composed of creatine phosphate kinase (CPK) microspheres, kinesins and microtubules is demonstrated. The CPK microsphere not only acts as an ATP generation and buffering system, but also as a carrier for cargo transport, thus realizing the easy loading and self-powered delivery of cargos at the same time. Electronic supplementary information (ESI) available: Experimental details, Fig. S1-S4, and Mov. S1-S6. See DOI: 10.1039/c4nr04454a

Inactivation of avirulent Yersinia pestis in Butterfield's phosphate buffer and frankfurters by UVC (254 nm) and gamma radiation.

PubMed

Sommers, Christopher H; Cooke, Peter H

2009-04-01

Yersinia pestis is the causative agent of plague. Although rare, pharyngeal plague in humans has been associated with consumption or handling of meat prepared from infected animals. The risks of contracting plague from consumption of deliberately contaminated food are currently unknown. Gamma radiation is a penetrating form of electromagnetic radiation, and UVC radiation is used for decontamination of liquids or food surfaces. Gamma radiation D10-values (the radiation dose needed to inactivate 1 log unit pathogen) were 0.23 (+/-0.01) and 0.31 (+/-0.03) kGy for avirulent Y. pestis inoculated into Butterfield's phosphate buffer and onto frankfurter surfaces, respectively, at 0 degree C. A UVC radiation dose of 0.25 J/cm2 inactivated avirulent Y. pestis suspended in Butterfield's phosphate buffer. UVC radiation doses of 0.5 to 4.0 J/cm2 inactivated 0.97 to 1.20 log units of the Y. pestis surface inoculated onto frankfurters. A low gamma radiation dose of 1.6 kGy could provide a 5-log reduction and a UVC radiation dose of 1 to 4 J/cm2 would provide a 1-log reduction of Y. pestis surface inoculated onto frankfurters. Y. pestis was capable of growth on frankfurters during refrigerated storage (10 degrees C). Gamma radiation of frankfurters inhibited the growth of Y. pestis during refrigerated storage, and UVC radiation delayed the growth of Y. pestis.

Fracture toughness and fractography of dental cements, lining, build-up, and filling materials.

PubMed

Mueller, H J

1990-06-01

The plane strain fracture toughness (K1c) at 23 degrees C and the fractography of zinc phosphate and zinc polycarboxylate cements, buffered glass ionomer liner, amalgam alloy admixed glass ionomer build-up material, and glass ionomer, microfilled and conventionally filled bis-GMA resin composite filling materials were analyzed by elastic-plastic short-rod and scanning electron microscopy methodologies. Results indicated that significant differences occurred in their K1c's from the lowest to the highest in the following groups of materials, (i) buffered glass ionomer, (ii) zinc phosphate, glass ionomer, zinc polycarboxylate, and alloy mixed glass ionomer, (iii) microfilled resin, and (iv) conventionally filled resin. All materials except the microfilled resin, which fractured via crack jumping, fractured via smooth crack advance. Filler debonding without any crack inhibiting process was related to materials with low K1c values. The incorporation of either buffering compounds or alloy particles into glass ionomer had no beneficial effect upon fracture toughness. This was in contrast to microfilled and conventionally filled resins where either crack blunting or crack pinning processes, respectively, were likely involved with their increased K1c's. For microfilled resin, distinct radial zones positioned around the chevron apex and characterized by plastically deformed deposited material were related to distinct crack jumps that occurred in the load versus displacement behavior. Finally, for the two remaining materials of zinc phosphate and polycarboxylate, particle cleavage and matrix debonding for the former and shear yielding for the latter occurred.

High-performance liquid chromatography method for the simultaneous determination of sulfamethoxazole and trimethoprim in bovine milk using an on-line clean-up column.

PubMed

Pereira, A V; Cass, Q B

2005-11-05

A bidimensional HPLC method for the simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) in bovine milk has been developed and validated. After centrifugation, aliquots (150 microl) of milk samples were directly injected to a column-switching HPLC system. At the first step a RAM octyl-BSA column was employed to automatically remove proteins that otherwise would interfere with milk analysis. The mobile phase 0.01 M phosphate buffer pH 6.0:acetonitrile (95:5, v/v) was used in the first 5 min for the elution of milk proteins and then 0.01 M phosphate buffer pH 6.0:acetonitrile (83:17, v/v) for transfer SMX and TMP to the analytical column. The separation of SMX and TMP from one another and from other remaining milk components was performed on an octyl column using the mobile phase 0.01 M phosphate buffer pH 5.0:acetonitrile (82:18, v/v), which were detected by UV at 265 nm. The calibration graphs were linear in the concentration ranges of 25-800 ng/ml and 50-400 ng/ml for SMX and TMP, respectively. The intra- and inter-assay coefficients of variation were less than 15% for both drugs. The validated method was applied to the analysis of milk samples of twelve (two groups of six) cows after administration (intramuscular or subcutaneous) of a single recommended therapeutic dose of the SMX-TMP combination.

Thermophysical properties of carboxylic and amino acid buffers at subzero temperatures: relevance to frozen state stabilization.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-06-02

Macromolecules and other thermolabile biologicals are often buffered and stored in frozen or dried (freeze-dried) state. Crystallization of buffer components in frozen aqueous solutions and the consequent pH shifts were studied in carboxylic (succinic, malic, citric, tartaric acid) and amino acid (glycine, histidine) buffers. Aqueous buffer solutions were cooled from room temperature (RT) to -25 °C and the pH of the solution was measured as a function of temperature. The thermal behavior of frozen solutions was investigated by differential scanning calorimetry (DSC), and the crystallized phases were identified by X-ray diffractometry (XRD). Based on the solubility of the neutral species of each buffer system over a range of temperatures, it was possible to estimate its degree of supersaturation at the subambient temperature of interest. This enabled us to predict its crystallization propensity in frozen systems. The experimental and the predicted rank orderings were in excellent agreement. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartrate systems, at initial pH < pK(a)(2), only the most acidic buffer component (neutral form) crystallized on cooling, causing an increase in the freeze-concentrate pH. In glycine buffer solutions, when the initial pH was ∼3 units < isoelectric pH (pI = 5.9), β-glycine crystallization caused a small decrease in pH, while a similar effect but in the opposite direction was observed when the initial pH was ∼3 units > pI. In the histidine buffer system, depending on the initial pH, either histidine or histidine HCl crystallized.

Inhibition of protein carbamylation in urea solution using ammonium-containing buffers.

PubMed

Sun, Shisheng; Zhou, Jian-Ying; Yang, Weiming; Zhang, Hui

2014-02-01

Urea solution is one of the most commonly employed protein denaturants for protease digestion in proteomic studies. However, it has long been recognized that urea solution can cause carbamylation at the N termini of proteins/peptides and at the side chain amino groups of lysine and arginine residues. Protein/peptide carbamylation blocks protease digestion and affects protein identification and quantification in mass spectrometry analysis by blocking peptide amino groups from isotopic/isobaric labeling and changing peptide charge states, retention times, and masses. In addition, protein carbamylation during sample preparation makes it difficult to study in vivo protein carbamylation. In this study, we compared the peptide carbamylation in urea solutions of different buffers and found that ammonium-containing buffers were the most effective buffers to inhibit protein carbamylation in urea solution. The possible mechanism of carbamylation inhibition by ammonium-containing buffers is discussed, and a revised procedure for the protease digestion of proteins in urea and ammonium-containing buffers was developed to facilitate its application in proteomic research. Copyright © 2013 Elsevier Inc. All rights reserved.

Phytosome-hyaluronic acid systems for ocular delivery of L-carnosine

PubMed Central

Abdelkader, Hamdy; Longman, Michael R; Alany, Raid G; Pierscionek, Barbara

2016-01-01

This study reports on L-carnosine phytosomes as an alternative for the prodrug N-acetyl-L-carnosine as a novel delivery system to the lens. L-carnosine was loaded into lipid-based phytosomes and hyaluronic acid (HA)-dispersed phytosomes. L-carnosine-phospholipid complexes (PC) of different molar ratios, 1:1 and 1:2, were prepared by the solvent evaporation method. These complexes were characterized with thermal and spectral analyses. PC were dispersed in either phosphate buffered saline pH 7.4 or HA (0.1% w/v) in phosphate buffered saline to form phytosomes PC1:1, PC1:2, and PC1:2 HA, respectively. These phytosomal formulations were studied for size, zeta potential, morphology, contact angle, spreading coefficient, viscosity, ex vivo transcorneal permeation, and cytotoxicity using primary human corneal cells. L-carnosine-phospholipid formed a complex at a 1:2 molar ratio and phytosomes were in the size range of 380–450 nm, polydispersity index of 0.12–0.2. The viscosity of PC1:2 HA increased by 2.4 to 5-fold compared with HA solution and PC 1:2, respectively; significantly lower surface tension, contact angle, and greater spreading ability for phytosomes were also recorded. Ex vivo transcorneal permeation parameters showed significantly controlled corneal permeation of L-carnosine with the novel carrier systems without any significant impact on primary human corneal cell viability. Ex vivo porcine lenses incubated in high sugar media without and with L-carnosine showed concentration-dependent marked inhibition of lens brunescence indicative of the potential for delaying changes that underlie cataractogenesis that may be linked to diabetic processes. PMID:27366062

Determination of chondroitin-6-sulphate by a competitive enzyme immunoassay using a biotinylated antigen.

PubMed

Kähnert, H; Brinkmann, T; Gässler, N; Kleesiek, K

1994-04-01

A competitive enzyme immunoassay was developed to determine chondroitin-6-sulphate in body fluids and cell cultures. The assay uses a monoclonal anti-chondroitin-6-sulphate antibody, immobilised to microtitre plates, and it involves a competitive binding reaction between chondroitin-6-sulphate in the samples and the biotinylated antigen. This assay enables the quantification of chondroitin-6-sulphate in the low concentration range of 16-120 micrograms/l. The intra-assay and inter-assay coefficients of variation are below 6.5% and 9.0%, respectively. More than 90% of chondroitin-6-sulphate was recovered when added to 0.1 mol/l phosphate-buffered saline, an albumin solution (40 g/l in phosphate-buffered saline) and cell culture medium (containing 100 ml/l foetal calf serum). Chondroitin-6-sulphate was also determined in sera of healthy male (n = 90) and female (n = 90) blood donors. The normal range was 55-169 micrograms/l. In men the mean value was estimated at 102.2 +/- 37.1 micrograms/l and in women at 98.7 +/- 26.4 micrograms/l. No age or sex dependence was observed. The urine excretion of chondroitin-6-sulphate in men (n = 16) was 44.5 +/- 21.1 mg/kg creatinine (mean +/- standard deviation) and in females (n = 10) 53.5 +/- 21.3 mg/kg creatinine. The clearance rate in men was 0.41 +/- 0.22 ml x min-1 and in women 0.38 +/- 0.15 ml x min-1. No sex dependence was found. Furthermore, the enzyme immunoassay was modified to measure the specific incorporation of a radioactively labelled precursor ([14C]galactosamine) into chondroitin-6-sulphate.(ABSTRACT TRUNCATED AT 250 WORDS)

Umbilical mesenchymal stromal cells provide intestinal protection through nitric oxide dependent pathways.

PubMed

Jensen, Amanda R; Drucker, Natalie A; Ferkowicz, Michael J; Markel, Troy A

2018-04-01

Umbilical-derived mesenchymal stromal cells (USCs) have shown promise in the protection of ischemic organs. We hypothesized that USCs would improve mesenteric perfusion, preserve intestinal histological architecture, and limit inflammation by nitric oxide-dependent mechanisms following intestinal ischemia/reperfusion (IR) injury. Adult wild-type C57BL/6J (WT) and endothelial nitric oxide synthase knock out (eNOS KO) mice were used: (1) WT IR + vehicle, (2) WT IR + USC, (3) eNOS KO IR + vehicle, and (4) eNOS KO IR + USC. Mice were anesthetized, and a midline laparotomy was performed. The superior mesenteric artery was clamped with a nonoccluding clamp for 60-min. Following IR, mice were treated with an injection of 250 μL phosphate buffered saline or 2 × 10 6 USCs suspended in 250-μL phosphate buffered saline solution. Mesenteric perfusion images were acquired using laser Doppler imaging. Perfusion was analyzed as a percentage of baseline. At 24 h, mice were euthanized, and intestines were harvested. Intestines were evaluated for injury, and data were analyzed using the Mann-Whitney or Kruskal-Wallis tests. Intestinal mesenteric perfusion was significantly improved in WT mice treated with USC therapy compared with eNOS KOs. Intestinal histological architecture was preserved with USC therapy in WT mice. However, in eNOS KO mice, this benefit was abolished. Finally, the presence of several cytokines and growth factors were significantly improved in WT mice compared with eNOS KO mice treated with USCs. The benefits of USC-mediated therapy following intestinal IR injury likely occur via nitric oxide-dependent pathways. Further studies are required to define the molecular mechanisms by which USCs activate endothelial nitric oxide synthase to bring about their protective effects. Copyright © 2017 Elsevier Inc. All rights reserved.

Tumor Necrosis Factor-induced Decrease of Cochlear Blood Flow Can Be Reversed by Etanercept or JTE-013.

PubMed

Sharaf, Kariem; Ihler, Friedrich; Bertlich, Mattis; Reichel, Christoph A; Berghaus, Alexander; Canis, Martin

2016-08-01

This study aimed to quantify the effects of tumor necrosis factor (TNF) inhibitor Etanercept and sphingosine-1-phosphate receptor 2 antagonist JTE-013 on cochlear blood flow in guinea pigs after TNF-induced decrease. Sudden sensorineural hearing loss is a common cause for disability and reduced quality of life. Good understanding of the pathophysiology and strong evidence-based therapy concepts are still missing. In various inner ear disorders, inflammation and impairment of cochlear blood flow (CBF) have been considered factors in the pathophysiology. A central mediator of inflammation and microcirculation in the cochlea is TNF. S1P acts downstream in one TNF pathway. Cochlea lateral wall vessels were exposed surgically and assessed by intravital microscopy in guinea pigs in vivo. Twenty-eight animals were randomly distributed into four groups of seven each. Exposed vessels were superfused by TNF (5.0 ng/ml) and afterward repeatedly either by Etanercept (1.0 μg/ml), JTE-013 (10 μmol/L), or vehicle (0.9 % NaCl solution or ethanol: phosphate-buffered saline buffer, respectively). After decreasing CBF with TNF (p <0.001, two-way RM ANOVA), both treatments reversed CBF, compared with vehicle (p <0.001, two-way RM ANOVA). The comparison of the vehicle groups showed no difference (p = 0.969, two-way RM ANOVA), while there was also no difference between the treatment groups (p = 0.850, two-way RM ANOVA). Both Etanercept and JTE-013 reverse the decreasing effect of TNF on cochlear blood flow and, therefore, TNF and the S1P-signalling pathway might be targets for treatment of microcirculation-related hearing loss.

Analysis of spiramycin by capillary electrophoresis.

PubMed

González-Hernández, R; Li, Y M; Van Schepdael, A; Roets, E; Hoogmartens, J

1999-09-01

The development and validation of an analytical method for the determination of spiramycin I in the presence of its related substances by capillary electrophoresis is shown. The separation, performed in a phosphate buffer (80 mM, pH 7.5) containing 12 mM cetyltrimethylammonium bromide (CTAB) and 20 mM sodium cholate, with a 50 microm ID and 44 cm long fused-silica capillary (36 cm effective length), applying a voltage of 12 kV (l approximately 80 microA), at 25 degrees C, is achieved in 15 min. Good selectivity among spiramycin I and its related substances was obtained. The influence of the buffer pH, and of the CTAB and sodium cholate concentrations was investigated. The method robustness, examined by means of a full-fraction factorial design, shows that it can be used within the limits set for the three parameters that were investigated. The method is linear (r = 0.9992) and precise (day-to-day corrected peak area repeatability, n = 18, relative standard deviation = 1.3%). The limits of detection and quantitation are 7 pg (0.025%) and 22 pg (0.08%), respectively, relative to a 2 mg/mL solution.

Stability of polymer encapsulated quantum dots in cell culture media

NASA Astrophysics Data System (ADS)

Ojea-Jiménez, I.; Piella, J.; Nguyen, T.-L.; Bestetti, A.; Ryan, A. D.; Puntes, V.

2013-04-01

The unique optical properties of Quantum Dots have attracted a great interest to use these nanomaterials in diverse biological applications. The synthesis of QDs by methods from the literature permits one to obtain nanocrystals coated by hydrophobic alkyl coordinating ligands and soluble in most of the cases in organic solvents. The ideal biocompatible QD must be homogeneously dispersed and colloidally stable in aqueous solvents, exhibit pH and salt stability, show low levels of nonspecific binding to biological components, maintain a high quantum yield, and have a small hydrodynamic diameter. Polymer encapsulation represents an excellent scaffold on which to build additional biological function, allowing for a wide range of grafting approaches for biological ligands. As these QD are functionalized with poly(ethylene)glycol (PEG) derivatives on their surface, they show long term stability without any significant change in the optical properties, and they are also highly stable in the most common buffer solutions such as Phosphate Buffer Saline (PBS) or borate. However, as biological studies are normally done in more complex biological media which contain a mixture of amino acids, salts, glucose and vitamins, it is essential to determine the stability of our synthesized QDs under these conditions before tackling biological studies.

Formation of apatitic calcium phosphates in a Na-K-phosphate solution of pH 7.4.

PubMed

Tas, A C; Aldinger, F

2005-02-01

Poorly crystalline, apatitic calcium phosphate powders have been synthesized by slowly adding a Na- and K-containing reference phosphate solution with a pH value of 7.4 to an aqueous calcium nitrate solution at 37 degrees C. Nano-particulated apatitic powders obtained were shown to contain small amounts of Na and K, which render them more similar in chemical composition to that of the bone mineral. Precipitated and dried powders were found to exhibit self-hardening cement properties when kneaded in a mortar with a sodium citrate- and sodium phosphate-containing starter solution. The same phosphate solution used in powder synthesis was found to be able to partially convert natural, white and translucent marble pieces of calcite (CaCO3) into calcium-deficient hydroxyapatite upon aging the samples in that solution for 3 days at 60 degrees C. Sample characterization was performed by using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, inductively-coupled plasma atomic emission spectroscopy, and simultaneous thermogravimetry and differential thermal analysis.

Characterization of drug release from liposomal formulations in ocular fluid.

PubMed

Jafari, M R; Jones, A B; Hikal, A H; Williamson, J S; Wyandt, C M

1998-01-01

The successful application of liposomes in topical ophthalmic drug delivery requires knowledge of vesicle stabilization in the presence of tear fluid. The release of procaine hydrochloride (PCH) from large unilamellar liposomes in the presence of simulated tear fluid was studied in vitro as a function of bilayer lipid content and tear protein composition. Reverse-phase evaporation vesicles were prepared from egg phosphatidylcholine, stearylamine or dicetyl phosphate, and cholesterol. The relationship between lipid composition and encapsulation efficiency, vesicle size, drug leakage upon storage at 4 degrees C, and the release of PCH-loaded liposomes was studied. The encapsulation efficiency was found to be dependent upon the lipid composition used in the liposome preparation. In particular, phosphatidylcholine vesicles containing cholesterol and/or charged lipids had a lower entrapment efficiency than liposomes prepared with phosphatidylcholine alone. However, the drug release rate was reduced significantly by inclusion of cholesterol and/or charged lipids in the liposomes. The release kinetics of the entrapped agent seemed to be a biphasic process and the drug-release in both simulated tear fluid (STF) and pH 7.4 phosphate buffered saline (PBS) solutions followed pseudo first-order kinetics in the early stage of the release profile. The drug-release appeared to be diffusion and/or partition controlled. Drug release from liposomes into STF, pH 7.4 PBS, and five different modified tear formulations was also evaluated. While serum-induced leakage is attributed to high-density lipoprotein-mediated destabilization, it was determined that lactoferrin might be the protein component in tear fluid that has the primary influence on the liposome-entrapped drug release rate. Five local anesthetics, benoxinate, proparacaine, procaine, tetracaine, and benzocaine were entrapped in liposomal vesicles by a reverse-phase evaporation (REV) technique. The release of these structurally similar topical anesthetics entrapped in positively charged liposomes (egg phosphatidylcholine, stearylamine, and cholesterol in a 7:2:1 molar ratio) was evaluated in a simulated tear fluid and pH 7.4 phosphate buffered saline solution. The liposomes appeared to be useful carriers for these drugs to retard their in vitro release in tear fluid and perhaps sustain or control their release in the eye for better therapeutic efficacy. An analysis of the release data demonstrated that for this series of drugs, drug partition coefficient has the largest effect on release rate, with molecular weight exhibiting a smaller effect. Release rate was found to decrease with increased lipophilicity or increased molecular weight.

A validated chiral liquid chromatographic method for the enantiomeric separation of safinamide mesilate, a new anti-Parkinson drug.

PubMed

Zhang, Kai; Xue, Na; Shi, Xiaowei; Liu, Weina; Meng, Jing; Du, Yumin

2011-04-28

A enantioselective reversed-phase high performance liquid chromatographic method was developed for the enantiomeric resolution of safinamide mesilate, 2(S)-[4-(3-fluorobenzyloxy)benzylamino] propionamide methanesulfonate, a neuroprotectant with antiparkinsonian and anticonvulsant activity for the treatment of Parkinson disease. The enantiomers of safinamide mesilate were baseline resolved on a Chiralcel OD-RH (150mm×4.6mm, 5μm) column using a mobile phase system containing 300mM sodium di-hydrogen phosphate buffer (pH 3.0):methanol:acetonitrile (65:25:10, v/v/v). The resolution between the enantiomers was not less than 3.0. The pH value of buffer solution in the mobile phase has played a key role in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was validated and proved to be robust. The limit of detection and limit of quantification of (R)-enantiomer were found to be 15 and 50ng/mL, respectively, for 20μL injection volume. The percentage recovery of (R)-enantiomer was ranged from 94.2 to 103.7 in bulk drug samples of safinamide mesilate. The sample solution and mobile phase were found to be stable at least for 48h. The final optimized method was successfully applied to separate (R)-enantiomer from safinamide mesilate and was proven to be reproducible and accurate for the quantitative determination of (R)-enantiomer in bulk drugs. Copyright © 2010 Elsevier B.V. All rights reserved.

Electrochemical lactate biosensor based upon chitosan/carbon nanotubes modified screen-printed graphite electrodes for the determination of lactate in embryonic cell cultures.

PubMed

Hernández-Ibáñez, Naiara; García-Cruz, Leticia; Montiel, Vicente; Foster, Christopher W; Banks, Craig E; Iniesta, Jesús

2016-03-15

l-lactate is an essential metabolite present in embryonic cell culture. Changes of this important metabolite during the growth of human embryo reflect the quality and viability of the embryo. In this study, we report a sensitive, stable, and easily manufactured electrochemical biosensor for the detection of lactate within embryonic cell cultures media. Screen-printed disposable electrodes are used as electrochemical sensing platforms for the miniaturization of the lactate biosensor. Chitosan/multi walled carbon nanotubes composite have been employed for the enzymatic immobilization of the lactate oxidase enzyme. This novel electrochemical lactate biosensor analytical efficacy is explored towards the sensing of lactate in model (buffer) solutions and is found to exhibit a linear response towards lactate over the concentration range of 30.4 and 243.9 µM in phosphate buffer solution, with a corresponding limit of detection (based on 3-sigma) of 22.6 µM and exhibits a sensitivity of 3417 ± 131 µAM(-1) according to the reproducibility study. These novel electrochemical lactate biosensors exhibit a high reproducibility, with a relative standard deviation of less than 3.8% and an enzymatic response over 82% after 5 months stored at 4 °C. Furthermore, high performance liquid chromatography technique has been utilized to independently validate the electrochemical lactate biosensor for the determination of lactate in a commercial embryonic cell culture medium providing excellent agreement between the two analytical protocols. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorption of Hydrophobin-Protein Mixtures at the Air-Water Interface: The Impact of pH and Electrolyte.

PubMed

Tucker, Ian M; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K; Cox, Andrew R; Hedges, Nick

2015-09-15

The adsorption of the proteins β-casein, β-lactoglobulin, and hydrophobin, and the protein mixtures of β-casein/hydrophobin and β-lactoglobulin/hydrophobin have been studied at the air-water interface by neutron reflectivity, NR. Changing the solution pH from 7 to 2.6 has relatively little impact on the adsorption of hydrophobin or β-lactoglobulin, but results in a substantial change in the structure of the adsorbed layer of β-casein. In β-lactoglobulin/hydrophobin mixtures, the adsorption is dominated by the hydrophobin adsorption, and is independent of the hydrophobin or β-lactoglobulin concentration and solution pH. At pH 2.6, the adsorption of the β-casein/hydrophobin mixtures is dominated by the hydrophobin adsorption over the range of β-casein concentrations studied. At pH 4 and 7, the adsorption of β-casein/hydrophobin mixtures is dominated by the hydrophobin adsorption at low β-casein concentrations. At higher β-casein concentrations, β-casein is adsorbed onto the surface monolayer of hydrophobin, and some interpenetration between the two proteins occurs. These results illustrate the importance of pH on the intermolecular interactions between the two proteins at the interface. This is further confirmed by the impact of PBS, phosphate buffered saline, buffer and CaCl2 on the coadsorption and surface structure. The results provide an important insight into the adsorption properties of protein mixtures and their application in foam and emulsion stabilization.

Sampling and detection of Legionella pneumophila aerosols generated from an industrial cooling tower.

PubMed

Ishimatsu, S; Miyamoto, H; Hori, H; Tanaka, I; Yoshida, S

2001-08-01

Cooling tower water has frequently been cited as a source of infection in outbreaks of Legionnaires' disease. However, there have been few reports on the presence of legionellae in aerosols from cooling towers. This paper describes our use of an impinger or a six-stage microbial impactor for detecting legionellae in air around a cooling tower contaminated with L. pneumophila (1.2+/-0.3x10(5) CFU/100 ml). Phosphate-buffered saline, Page's saline, 2% yeast extract solution and buffered yeast extract (BYE) broth were tested to evaluate their collection efficiency. These solutions were compared in laboratory experiments using an aerosol of L. pneumophila serogroup (SG) 1. Because BYE broth was the most efficient and storable collecting fluid among them, it was used for outdoor air sampling. In the outdoor air sampling, aerosolized L. pneumophila SG 6 was detected in the air around the cooling tower by the impinger (0.09 CFU/l. air). No legionellae were detected by the impactor with Legionella-selective agar plates (WYOalpha) because the plates were overgrown with fungi. Repetitive element PCR (rep-PCR) and arbitrarily primed PCR (AP-PCR) were employed to assess the epidemiological relationship among Legionella isolates from the air sample and the cooling tower water samples. L. pneumophila SG 6 isolated from the aerosols produced rep-PCR and AP-PCR fingerprints identical to those of L. pneumophila SG 6 strains from the cooling tower water, suggesting that the bacterium was aerosolized from the cooling tower.

Online sample concentration and analysis of drugs of abuse in human urine by micelle to solvent stacking in capillary zone electrophoresis.

PubMed

Aturki, Zeineb; Fanali, Salvatore; Rocco, Anna

2016-10-01

A sensitive and rapid CZE-UV method was developed to determine drugs and their metabolites' presence in human urine. Ten drugs of abuse were analyzed including four amphetamines, cocaine, cocaethylene, heroin, morphine, 6-monoacetylmorphine, and 4-methylmethcathinone. An MSS (micelle to solvent stacking) approach was evaluated to enhance method sensitivity. This method considers composition of the micellar sample solution matrix and the injection time. Several analytical conditions influencing the resolution of the drugs mixture as pH and buffer concentration, organic solvent content, were also investigated. The base-line separation of all studied analytes in the same run was achieved within 18 min in an uncoated fused silica capillary (50 μm id × 60 cm) using a background solution containing 50 mM phosphate buffer pH 2.5 and 30% ACN v/v. Other experimental parameters such as applied voltage and capillary temperature were set up at 20 kV and 20°C, respectively. LOD values ranging between 15 and 75 ng/mL for all studied compounds were obtained. From a comparison with conventional CZE, the proposed method provides an increase of sensitivity (39- to 55-fold enhancement factor). Under optimal MSS-CZE conditions, good linearity was achieved (R 2 ≤ 0.9998). The method was finally applied to the analysis of urine samples spiked with a standard mixture after a sample pretreatment, reaching satisfactory recovery values. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer.

PubMed

Jung, Jaehyo; Lee, Jihoon; Shin, Siho; Kim, Youn Tae

2017-10-23

In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V) converter to convert the current generated by the reduction-oxidation (redox) reaction of the buffer solution to a voltage signal. This signal is then digitized by the processor. The configuration of the power and ground of the printed circuit board (PCB) layer is divided into digital and analog parts to minimize the noise interference of each part. The proposed analyzer occupies an area of 5.9 × 3.25 cm² with a current resolution of 0.4 nA. A potential of 0~2.1 V can be applied between the working and the counter electrodes. The results of this study showed the accuracy of the proposed analyzer by measuring the Ruthenium(III) chloride ( Ru III ) concentration in 10 mM phosphate-buffered saline (PBS) solution with a pH of 7.4. The measured data can be transmitted to a PC or a mobile such as a smartphone or a tablet PC using the included Bluetooth module. The proposed analyzer uses a 3.7 V, 120 mAh lithium polymer battery and can be operated for 60 min when fully charged, including data processing and wireless communication.

Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer

PubMed Central

Lee, Jihoon; Shin, Siho; Kim, Youn Tae

2017-01-01

In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V) converter to convert the current generated by the reduction-oxidation (redox) reaction of the buffer solution to a voltage signal. This signal is then digitized by the processor. The configuration of the power and ground of the printed circuit board (PCB) layer is divided into digital and analog parts to minimize the noise interference of each part. The proposed analyzer occupies an area of 5.9 × 3.25 cm2 with a current resolution of 0.4 nA. A potential of 0~2.1 V can be applied between the working and the counter electrodes. The results of this study showed the accuracy of the proposed analyzer by measuring the Ruthenium(III) chloride (RuIII) concentration in 10 mM phosphate-buffered saline (PBS) solution with a pH of 7.4. The measured data can be transmitted to a PC or a mobile such as a smartphone or a tablet PC using the included Bluetooth module. The proposed analyzer uses a 3.7 V, 120 mAh lithium polymer battery and can be operated for 60 min when fully charged, including data processing and wireless communication. PMID:29065534

Stable adducts of nerve agents sarin, soman and cyclosarin with TRIS, TES and related buffer compounds--characterization by LC-ESI-MS/MS and NMR and implications for analytical chemistry.

PubMed

Gäb, Jürgen; John, Harald; Melzer, Marco; Blum, Marc-Michael

2010-05-15

Buffering compounds like TRIS are frequently used in chemical, biochemical and biomedical applications to control pH in solution. One of the prerequisites of a buffer compound, in addition to sufficient buffering capacity and pH stability over time, is its non-reactivity with other constituents of the solution. This is especially important in the field of analytical chemistry where analytes are to be determined quantitatively. Investigating the enzymatic hydrolysis of G-type nerve agents sarin, soman and cyclosarin in buffered solution we have identified stable buffer adducts of TRIS, TES and other buffer compounds with the nerve agents. We identified the molecular structure of these adducts as phosphonic diesters using 1D (1)H-(31)P HSQC NMR and LC-ESI-MS/MS techniques. Reaction rates with TRIS and TES are fast enough to compete with spontaneous hydrolysis in aqueous solution and to yield substantial amounts (up to 20-40%) of buffer adduct over the course of several hours. A reaction mechanism is proposed in which the amino function of the buffer serves as an intramolecular proton acceptor rendering the buffer hydroxyl groups nucleophilic enough for attack on the phosphorus atom of the agents. Results show that similar buffer adducts are formed with a range of hydroxyl and amino function containing buffers including TES, BES, TRIS, BIS-TRIS, BIS-TRIS propane, Tricine, Bicine, HEPES and triethanol amine. It is recommended to use alternative buffers like MOPS, MES and CHES when working with G-type nerve agents especially at higher concentrations and over prolonged times. Copyright (c) 2010 Elsevier B.V. All rights reserved.

INACTIVATION OF HEPATITIS A VIRUS AND MS2 BY OZONE AND OZONE-HYDROGEN PEROXIDE IN BUFFERED WATER

EPA Science Inventory

The comparative inactivation of highly purified hepatitis A virus (HAV) and MS2 by 1 mg H202/L, 2.0 and 0.4 mg 03/L, and 2.0 mg 03/L plus 0.6, 1.0, or 1.6 mg H202/L, at 3-10 degrees C, in 0.01 M phosphate buffer (pH 6-10) was determined. Both HAV and MS2 were completely inactivat...

ISS Internal Active Thermal Control System (IATCS) Coolant Remediation Project

NASA Technical Reports Server (NTRS)

Morrison, Russell H.; Holt, Mike

2005-01-01

The IATCS coolant has experienced a number of anomalies in the time since the US Lab was first activated on Flight 5A in February 2001. These have included: 1) a decrease in coolant pH, 2) increases in inorganic carbon, 3) a reduction in phosphate buffer concentration, 4) an increase in dissolved nickel and precipitation of nickel salts, and 5) increases in microbial concentration. These anomalies represent some risk to the system, have been implicated in some hardware failures and are suspect in others. The ISS program has conducted extensive investigations of the causes and effects of these anomalies and has developed a comprehensive program to remediate the coolant chemistry of the on-orbit system as well as provide a robust and compatible coolant solution for the hardware yet to be delivered. The remediation steps include changes in the coolant chemistry specification, development of a suite of new antimicrobial additives, and development of devices for the removal of nickel and phosphate ions from the coolant. This paper presents an overview of the anomalies, their known and suspected system effects, their causes, and the actions being taken to remediate the coolant.

Solid-phase extraction of small biologically active peptides on cartridges and microelution 96-well plates from human urine.

PubMed

Semenistaya, Ekaterina; Zvereva, Irina; Krotov, Grigory; Rodchenkov, Grigory

2016-09-01

Currently liquid chromatography - mass spectrometry (LC-MS) analysis after solid-phase extraction (SPE) on weak cation-exchange cartridges is a method of choice for anti-doping analysis of small bioactive peptides such as growth hormone releasing peptides (GHRPs), desmoporessin, LHRH, and TB-500 short fragment. Dilution of urine samples with phosphate buffer for pH adjustment and SPE on weak cation exchange microelution plates was tested as a means to increase throughput of this analysis. Dilution using 200 mM phosphate buffer provides good buffering capacity without affecting the peptides recoveries. SPE on microelution plates was performed on Waters Positive Pressure-96 Processor with subsequent evaporation of eluates in nitrogen flow. Though the use of smaller sample volume decreases the pre-concentration factor and increases the limits of detection of 5 out of 17 detected peptides, the recovery, linearity, and reproducibility of the microelution extraction were comparable with cartridge SPE. The effectiveness of protocols was confirmed by analysis of urine samples containing ipamorelin, and GHRP-6 and its metabolites. SPE after urine sample dilution with buffer can be used for faster sample preparation. The use of microelution plates decreases consumption of solvents and allows processing of up to 96 samples simultaneously. Cartridge SPE with manual рН adjustment remains the best option for confirmation. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Preparation and properties of BSA-loaded microspheres based on multi-(amino acid) copolymer for protein delivery

PubMed Central

Chen, Xingtao; Lv, Guoyu; Zhang, Jue; Tang, Songchao; Yan, Yonggang; Wu, Zhaoying; Su, Jiacan; Wei, Jie

2014-01-01

A multi-(amino acid) copolymer (MAC) based on ω-aminocaproic acid, γ-aminobutyric acid, L-alanine, L-lysine, L-glutamate, and hydroxyproline was synthetized, and MAC microspheres encapsulating bovine serum albumin (BSA) were prepared by a double-emulsion solvent extraction method. The experimental results show that various preparation parameters including surfactant ratio of Tween 80 to Span 80, surfactant concentration, benzyl alcohol in the external water phase, and polymer concentration had obvious effects on the particle size, morphology, and encapsulation efficiency of the BSA-loaded microspheres. The sizes of BSA-loaded microspheres ranged from 60.2 μm to 79.7 μm, showing different degrees of porous structure. The encapsulation efficiency of BSA-loaded microspheres also ranged from 38.8% to 50.8%. BSA release from microspheres showed the classic biphasic profile, which was governed by diffusion and polymer erosion. The initial burst release of BSA from microspheres at the first week followed by constant slow release for the next 7 weeks were observed. BSA-loaded microspheres could degrade gradually in phosphate buffered saline buffer with pH value maintained at around 7.1 during 8 weeks incubation, suggesting that microsphere degradation did not cause a dramatic pH drop in phosphate buffered saline buffer because no acidic degradation products were released from the microspheres. Therefore, the MAC microspheres might have great potential as carriers for protein delivery. PMID:24855351

Cold physical plasma treated buffered saline solution as effective agent against pancreatic cancer cells.

PubMed

Bekeschus, Sander; Kading, Andre; Schroder, Tim; Wende, Kristian; Hackbarth, Christine; Liedtke, Kim Rouven; van der Linde, Julia; von Woedtke, Thomas; Heidecke, Claus-Dieter; Partecke, Lars-Ivo

2018-05-07

Cold physical plasma has been suggested as a new anticancer tool recently. However, direct use of plasma is limited to visible tumors and in some clinical situations not feasible. This includes repetitive treatment of peritoneal metastases which commonly occur in advanced gastrointestinal cancer and in pancreatic cancer in particular. In case of diffuse intraperitoneal metastatic spread Hyperthermic Intraperitoneal Intraoperative Chemotherapy (HIPEC) is used as therapeutic approach. Plasma treated solutions may combine their suspected systemic non-toxic characteristics with the anticancer effects of HIPEC. Previous work has provided evidence for an anti-cancer efficacy of plasma treated cell culture medium but the clinical relevance of such an approach is low due to its complex formulation and lack of medical accreditation. Therefore, plasma treated phosphate-buffered saline (PBS) which closely resembles medically certified solutions was investigated for its cytotoxic effect on 2D monolayer murine pancreatic cancer cells in vitro. It significantly decreased cancer cell metabolisms and proliferation whereas plasma treated Dulbecco's Modified Eagle Medium had no effect. Moreover, tumor cell growth attenuation was significantly higher when compared to syngeneic primary murine fibroblasts. Both results were confirmed in a human pancreatic cancer cell line. Finally, plasma treated PBS also decreased tumor sizes of pancreatic tumors in the TUM-CAM model in a three-dimensional manner, and induction of apoptosis was found to be responsible for all anticancer effects identified. Altogether, plasma treated PBS inhibited cell growth in 2D and 3D models of cancer. These results may help facilitating the development of new plasma derived anticancer agent with clinical relevance in the future. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Radiofrequency Electric Field Heating of Conductive Media: Understanding Aqueous and Nanoparticle Heating Mechanisms and a Method for Heating Optimization

NASA Astrophysics Data System (ADS)

Lara, Nadia Chantal

Use of radiofrequency (RF) electric fields coupled with nanoparticles to enhance non-invasive hyperthermia in cancer cells and tumors sparked debate over the RF heating mechanisms of nanoparticles and the role of salts in heating. Under RF field exposure at 13.56 MHz, aqueous systems including electrolyte solutions, buffers, and blood, were shown to heat according to bulk material properties, regardless of composition. This universal aqueous heating behavior extended to suspensions of nanoparticles such as gold nanoparticles, full-length and ultra-short single-walled carbon nanotubes, and water-soluble fullerene derivatives. These suspensions displayed the same RF heating properties as saline solutions of the same conductivity, indicating that these nanoparticles themselves do not contribute to RF heating by any unique mechanism; rather, they modulate bulk conductivity, which in turn affects bulk RF heating. At 13.56 MHz, peak heating for an aqueous system occurs at a conductivity of 0.06 S/m, beyond which increases in conductivity result in reduced heating rates. Biologically relevant materials, such as blood, intra- and extracellular fluids, and most human tissues, exceed this peak heating conductivity, precluding the use of conductive materials for RF heating rate enhancement. Instead, kosmotropic or water-structuring materials, including sugars, glycols, zwitterionic molecules, and a water-soluble fullerene derivative, when added to blood or phosphate buffered saline reduced the bulk conductivity of these materials and enhanced their heating rates accordingly. A dielectric heating rate model taking into account the geometry of the sample under RF exposure was used to explain the experimental RF heating behavior of aqueous solutions and semi-aqueous materials, which generated distinct RF heating curves due to differences in bulk dielectric and physical properties.

Dynamics of human serum albumin studied by acoustic relaxation spectroscopy.

PubMed

Hushcha, T; Kaatze, U; Peytcheva, A

Sonic absorption spectra of solutions of human serum albumin (SA) in water and in aqueous phosphate buffer systems have been measured between 0.2 and 2000 MHz at different temperatures (15-35 degrees C), pH values (1.8-12.3), and protein concentrations (1-40 g/L). Several spectra, indicating relaxation processes in the whole frequency range, have been found. The spectra at neutral pH could be fitted well with an analytical function consisting of the asymptotic high frequency absorption and two relaxation contributions, a Debye-type relaxation term with discrete relaxation time and a term with asymmetric continuous distribution of relaxation times. Both relaxation contributions were observed in water and in buffer solutions and increased with protein concentration. The contribution represented by a Debye-type term is practically independent of temperature and was attributed to cooperative conformational changes of the polypeptide chain featuring a relaxation time of about 400 ns. The distribution of the relaxation times corresponding to the second relaxation contribution was characterized by a short time cutoff, between about 0.02 and 0.4 ns depending on temperature, and a long time tail extending to microseconds. Such relaxation behavior was interpreted in terms of solute-solvent interactions reflecting various hydration layers of HSA molecules. At acid and alkaline pH, an additional Debye-type contribution with relaxation time in the range of 30-100 ns exists. It seems to be due to proton transfer reactions of protein side-chain groups. The kinetic and thermodynamic parameters of these processes have been estimated from these first measurements to indicate the potential of acoustic spectra for the investigation of the elementary kinetics of albumin processes. Copyright 2004 Wiley Periodicals, Inc. Biopolymers, 2004

Ultrasonication as a potential tool to predict solute crystallization in freeze-concentrates.

PubMed

Ragoonanan, Vishard; Suryanarayanan, Raj

2014-06-01

We hypothesize that ultrasonication can accelerate solute crystallization in freeze-concentrates. Our objective is to demonstrate ultrasonication as a potential predictive tool for evaluating physical stability of excipients in frozen solutions. The crystallization tendencies of lyoprotectants (trehalose, sucrose), carboxylic acid buffers (citric, tartaric, malic, and acetic) and an amino acid buffer (histidine HCl) were studied. Aqueous solutions of buffers, lyoprotectants and mixtures of the two were cooled from room temperature to -20°C and sonicated to induce solute crystallization. The crystallized phases were identified by X-ray diffractometry (laboratory or synchrotron source). Sonication accelerated crystallization of trehalose dihydrate in frozen trehalose solutions. Sonication also enhanced solute crystallization in tartaric (200 mM; pH 5), citric (200 mM pH 4) and malic (200 mM; pH 4) acid buffers. At lower buffer concentrations, longer annealing times following sonication were required to facilitate solute crystallization. The time for crystallization of histidine HCl progressively increased as a function of sucrose concentration. The insonation period required to effect crystallization also increased with sucrose concentration. Sonication can substantially accelerate solute crystallization in the freeze-concentrate. Ultrasonication may be useful in assessing the crystallization tendency of formulation constituents used in long term frozen storage and freeze-drying.

Report of the key comparison APMP.QM-K19. APMP comparison on pH measurement of borate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Asakai, Toshiaki; Maksimov, Igor; Suzuki, Toshihiro; Miura, Tsutomu; Obromsook, Krairerk; Tangpaisarnkul, Nongluck; Rodruangthum, Patumporn; Wong, Siu-Kay; Lam, Wai-Hing; Zakaria, Osman; Anuar Mohd. Amin, Khirul; Thanh, Ngo Huy; Máriássy, Michal; Vyskocil, Leos; Hankova, Zuzana; Fisicaro, Paola; Stoica, Daniela; Singh, Nahar; Soni, Daya; Ticona Canaza, Galia; Kutovoy, Viatcheslav; Barbieri Gonzaga, Fabiano; Dias, Júlio Cesar; Vospelova, Alena; Bakovets, Nickolay; Zhanasbayeva, Bibinur

2015-01-01

The APMP.QM-K19 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a borate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan (NMIJ) and the National Institute of Metrology (Thailand) (NIMT) at the APMP-TCQM meeting held 26-27 November 2012. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K19 and CCQM-K19.1. The comparison material was a borate buffer of pH around 9.2 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the second APMP key comparison on pH measurement and the fourth APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004, APMP.QM-P09 (a phthalate buffer) in 2006 and APMP.QM-K9/APMP.QM-P16 (a phosphate buffer) in 2010-2011. The results can be used further by any participant to support its CMC claim at least for a borate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

In vitro and in vivo evaluation of self-nanoemulsifying drug delivery systems of cilostazol for oral and parenteral administration.

PubMed

Mahmoud, Dina B; Shukr, Marwa H; Bendas, Ehab R

2014-12-10

The current investigation was aimed to improve the solubility of poorly soluble drug, cilostazol (CLZ). Self-nanoemulsifying drug delivery system (SNEDDS) composed of oil, surfactant and co-surfactant for both oral and parenteral administration of CLZ was formulated. The components for SNEDDS were identified by solubility studies, and pseudo-ternary phase diagrams were plotted to identify the efficient self-emulsification regions. The optimum formula, composed of Capryol 90 as an oil phase, Cremophor EL as a surfactant, and Transcutol HP as a co-surfactant in a ratio of 19.8:30.5:49.7 by weight, was able to solubilize CLZ 2000 times higher than its solubility in water. This formula was able to form grade "A" nanoemulsion when diluted with water, resulted in emulsification time of 50±1.1 s, particle size of 14.3 nm, PDI of 0.5 and % transmittance was 97.40%±0.65. It showed excellent in vitro dissolution of 93.1% and 81.5% after 5 min in 0.3% sodium lauryl sulphate solution and phosphate buffer pH 6.4, respectively when compared with the marketed tablet formulation and drug suspension as the tablets showed only 44.3% and 9.9% while CLZ suspension showed 33.9% and 8.8% in 0.3% sodium lauryl sulphate solution and phosphate buffer pH 6.4, respectively. It was found to be robust to dilution, thermodynamically stable with low viscosity values of 14.20±0.35 cP. In vivo study revealed significant increase in bioavailability of CLZ in rabbits to 3.94 fold compared with the marketed tablet formulation after oral administration. This formula could be sterilized by autoclaving and did not cause significant hemolysis to human blood which indicates its safety for intravenous administration with a 1.12 fold increase in bioavailability compared with its oral administration. Our study illustrated the potential use of SNEDDS of poorly soluble CLZ orally, and its successful administration of parenterally when required in acute cases of myocardial and cerebral infarction. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of the addition CNTs on performance of CaP/chitosan/coating deposited on magnesium alloy by electrophoretic deposition.

PubMed

Zhang, Jie; Wen, Zhaohui; Zhao, Meng; Li, Guozhong; Dai, Changsong

2016-01-01

CaP/chitosan/carbon nanotubes (CNTs) coating on AZ91D magnesium alloy was prepared via electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). The bonding between the layer and the substrate was studied by an automatic scratch instrument. The phase compositions and microstructures of the composite coatings were determined by using X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscope (SEM). The element concentration and gentamicin concentration were respectively determined by inductively coupled plasma optical emission spectrometer (ICP-OES) test and ultraviolet spectrophotometer (UV). The cell counting kit (CCK) assay was used to evaluate the cytotoxicity of samples to SaOS-2 cells. The results showed that a few CNTs with their original tubular morphology could be found in the CaP/chitosan coating and they were beneficial for the crystal growth of phosphate and improvement of the coating bonding when the addition amount of CNTs in 500 ml of electrophoretic solution was from 0.05 g to 0.125 g. The loading amount of gentamicin increased and the releasing speed of gentamicin decreased after CNTs was added into the CaP/chitosan coating for immersion loading and EPD loading. The cell viability of Mg based CaP/chitosan/CNTs was higher than that of Mg based CaP/chitosan from 16 days to 90 days. Copyright © 2015 Elsevier B.V. All rights reserved.

Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

DOE PAGES

Hurt, Jr., Richard A.; Robeson II, Michael S.; Shakya, Migun; ...

2014-07-14

Despite more than three decades of progress, efficient nucleic acid extraction from microbial communities has remained difficult, particularly from clay environments. Lysis with concentrated guanidine followed by concentrated sodium phosphate extraction supported DNA and RNA recovery from high iron, low humus content clay. Alterating the extraction pH or using other ionic solutions (Na 2SO 4 and NH 4H 2PO 4) yielded no detectable nucleic acid. DNA recovered using a lysis solution with 500 mM phosphate buffer (PB) followed by a 1 M PB wash was 15.22±2.33 g DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25more » g DNA/g clay with the Powerlyzer soil DNA system (MoBio). Increasing [PB] in the lysis reagent coincided with increasing DNA fragment length. Rarefaction plots based on16S rRNA (V1/V3 region) pyrosequencing libraries from A-horizon and clay soils showed an ~80% and ~400% larger accessed diversity compared to a previous grinding protocol or the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more bacterial species recovered using this system. Additionally, some OTU's having more than 100 sequences in these libraries were absent in samples extracted using the PowerLyzer reagents or the previous lysis method.« less

Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurt, Jr., Richard A.; Robeson II, Michael S.; Shakya, Migun

Despite more than three decades of progress, efficient nucleic acid extraction from microbial communities has remained difficult, particularly from clay environments. Lysis with concentrated guanidine followed by concentrated sodium phosphate extraction supported DNA and RNA recovery from high iron, low humus content clay. Alterating the extraction pH or using other ionic solutions (Na 2SO 4 and NH 4H 2PO 4) yielded no detectable nucleic acid. DNA recovered using a lysis solution with 500 mM phosphate buffer (PB) followed by a 1 M PB wash was 15.22±2.33 g DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25more » g DNA/g clay with the Powerlyzer soil DNA system (MoBio). Increasing [PB] in the lysis reagent coincided with increasing DNA fragment length. Rarefaction plots based on16S rRNA (V1/V3 region) pyrosequencing libraries from A-horizon and clay soils showed an ~80% and ~400% larger accessed diversity compared to a previous grinding protocol or the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more bacterial species recovered using this system. Additionally, some OTU's having more than 100 sequences in these libraries were absent in samples extracted using the PowerLyzer reagents or the previous lysis method.« less

Effect of the Dialysis Fluid Buffer on Peritoneal Membrane Function in Children

PubMed Central

Nau, Barbara; Gemulla, Gita; Bonzel, Klaus E.; Hölttä, Tuula; Testa, Sara; Fischbach, Michel; John, Ulrike; Kemper, Markus J.; Sander, Anja; Arbeiter, Klaus; Schaefer, Franz

2013-01-01

Summary Background and objectives Double-chamber peritoneal dialysis fluids exert less toxicity by their neutral pH and reduced glucose degradation product content. The role of the buffer compound (lactate and bicarbonate) has not been defined in humans. Design, setting, participants, & measurements A multicenter randomized controlled trial in 37 children on automated peritoneal dialysis was performed. After a 2-month run-in period with conventional peritoneal dialysis fluids, patients were randomized to neutral-pH, low-glucose degradation product peritoneal dialysis fluids with 35 mM lactate or 34 mM bicarbonate content. Clinical and biochemical monitoring was performed monthly, and peritoneal equilibration tests and 24-hour clearance studies were performed at 0, 3, 6, and 10 months. Results No statistically significant difference in capillary blood pH, serum bicarbonate, or oral buffer supplementation emerged during the study. At baseline, peritoneal solute equilibration and clearance rates were similar. During the study, 4-hour dialysis to plasma ratio of creatinine tended to increase, and 24-hour dialytic creatinine and phosphate clearance increased with lactate peritoneal dialysis fluid but not with bicarbonate peritoneal dialysis fluid. Daily net ultrafiltration, which was similar at baseline (lactate fluid=5.4±2.6 ml/g glucose exposure, bicarbonate fluid=4.9±1.9 ml/g glucose exposure), decreased to 4.6±1.0 ml/g glucose exposure in the lactate peritoneal dialysis fluid group, whereas it increased to 5.1±1.7 ml/g glucose exposure in the bicarbonate content peritoneal dialysis fluid group (P=0.006 for interaction). Conclusions When using biocompatible peritoneal dialysis fluids, equally good acidosis control is achieved with lactate and bicarbonate buffers. Improved long-term preservation of peritoneal membrane function may, however, be achieved with bicarbonate-based peritoneal dialysis fluids. PMID:23124784

Crystallization efficiencies of inorganic polyphosphate oligomers reacted with magnesium and calcium cations using anion-exchange chromatography with particulate formation-laser scattering detector.

PubMed

Ando, Masaki; Imadzu, Sakiyo; Kitagawa, Shinya; Ohtani, Hajime

2010-08-06

A particulate formation-laser scattering detector (PFLSD) was developed and used for evaluating the crystallization efficiency of inorganic polyphosphates (PPs) that reacted with either magnesium or calcium cations. As the solutions for reactive crystallization, 0.5 M ammonium buffer (pH 9.6) containing either 0.15 M MgCl(2) or 0.15 M CaCl(2) (MAP: magnesium ammonium phosphate and HAP: hydroxyapatite solution) were used. In the case of mono- and diphosphate (P1 and P2), the significant dependences of the particulate formation efficiency on various types of both P1/P2 and MAP/HAP reaction solutions were observed with the direct sample injection mode. The PFLSD was hyphenated with the anion-exchange chromatography and the dependence of the particulate formation efficiency on the polymerization degree (n(p)) of PP oligomers, separated chromatographically, was evaluated sequentially. The significant suppression of the particulate formation for PP oligomers was clearly confirmed, i.e., the MAP and HAP reaction solutions did not produce the particulates of the PP oligomers having an n(p) value of more than 3 and 5, respectively. As the overall tendency, the particulate formation efficiency in the case of the HAP solution was superior to that in the case of the MAP solution. Copyright 2010 Elsevier B.V. All rights reserved.

Role of histidine-related compounds to intracellular buffering in fish skeletal muscle.

PubMed

Abe, H; Dobson, G P; Hoeger, U; Parkhouse, W S

1985-10-01

Histidine-related compounds (HRC) were analyzed in fish skeletal muscle as a means of identifying their precise role in intracellular buffering. Fish muscle was used because it contains two functionally and spatially distinct fiber types, red and white. Two fish species, rainbow trout (Salmo gairdneri) and the Pacific blue marlin (Makaira nigricans), were studied because these species demonstrate widely different activity patterns. Marlin red and white muscle buffer capacity was two times higher than trout with white muscle, buffering being two times greater than red in both species. Buffer capacity was highest in the 6.5-7.5 pH range for all tissues, which corresponded to their high anserine levels. The titrated HRC buffering was greater than the observed HRC buffering, which suggested that not all HRC were available to absorb protons. The HRC contribution to total cellular buffering varied from a high of 62% for marlin white to a low of 7% for trout red. The other principal buffers were found to be phosphate and protein with taurine contributing within red muscle in the 7.0-8.0 pH range. HRC were found to be dominant in skeletal muscle buffering by principally accounting for the buffering capacity differences found between the species and fiber types.

Determination of monosaccharides derivatized with 2-aminobenzoic Acid by capillary electrophoresis.

PubMed

Abo, Mitsuru; He, Li-Ping; Sato, Kae; Okubo, Akira

2013-01-01

Reducing monosaccharides were derivatized with 2-aminobenzoic acid (2-AA) through reductive amination using sodium cyanoborohydride as a reductant, and the derivatives were separated by capillary zone electrophoresis with UV detection using 50 mM sodium phosphate (pH 5.5) or 150 mM sodium borate-50 mM sodium phosphate (pH 7.0) running buffer. The derivatives of monosaccharides, which are major components of various carbohydrate materials, were completely separated within 25 min.

Development of a new class of chemical and biological ultrasensors: Ribonuclease contamination and control

NASA Technical Reports Server (NTRS)

1984-01-01

In order to define ribonuclease contamination, an assay for ribonuclease having picogram level sensitivity was established. In this assay, polycytidylic acid is digested by ribonuclease leading to smaller fragments of poly C that remain soluble after treatment of the sample with perchloric acid and lanthanum acetate. An absorbance measurement at 260 nm of the supernatant from the centrifuged sample measures the ribonuclease. A standard curve is shown. Using this assay procedure, ribonuclease contamination was found to be significant in routine laboratory proteins, in particular, bovine serum albumin, lysozyme, catalase, and cytochrome C. This was confirmed by demonstrating a considerable reduction in this activity in the presence of phosphate buffer since phosphate inhibits ribonuclease. Ribonuclease contamination was not significantly encountered in routine laboratory glassware, plasticware, column surfaces, chromatographic particles, and buffer reagents, including airborne contamination. Some contamination could be introduced by fingerprints, however.

Synthesis of aldehyde-linked nucleotides and DNA and their bioconjugations with lysine and peptides through reductive amination.

PubMed

Raindlová, Veronika; Pohl, Radek; Hocek, Michal

2012-03-26

5-(5-Formylthienyl)-, 5-(4-formylphenyl)- and 5-(2-fluoro-5-formylphenyl)cytosine 2'-deoxyribonucleoside mono- (dC(R)MP) and triphosphates (dC(R)TP) were prepared by aqueous Suzuki-Miyaura cross-coupling of 5-iodocytosine nucleotides with the corresponding formylarylboronic acids. The dC(R)TPs were excellent substrates for DNA polymerases and were incorporated into DNA by primer extension or PCR. Reductive aminations of the model dC(R)MPs with lysine or lysine-containing tripeptide were studied and optimized. In aqueous phosphate buffer (pH 6.7) the yields of the reductive aminations with tripeptide III were up to 25 %. Bioconjugation of an aldehyde-containing DNA with a lysine-containing tripeptide was achieved through reductive amination in yields of up to 90 % in aqueous phosphate buffer. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phosphate-based glass fiber vs. bulk glass: Change in fiber optical response to probe in vitro glass reactivity.

PubMed

Massera, J; Ahmed, I; Petit, L; Aallos, V; Hupa, L

2014-04-01

This paper investigates the effect of fiber drawing on the thermal and structural properties as well as on the glass reactivity of a phosphate glass in tris(hydroxymethyl)aminomethane-buffered (TRIS) solution and simulated body fluid (SBF). The changes induced in the thermal properties suggest that the fiber drawing process leads to a weakening and probable re-orientation of the POP bonds. Whereas the fiber drawing did not significantly impact the release of P and Ca, an increase in the release of Na into the solution was noticed. This was probably due to small structural reorientations occurring during the fiber drawing process and to a slight diffusion of Na to the fiber surface. Both the powders from the bulk and the glass fibers formed a Ca-P surface layer when immersed in SBF and TRIS. The layer thickness was higher in the calcium and phosphate supersaturated SBF than in TRIS. This paper for the first time presents the in vitro reactivity and optical response of a phosphate-based bioactive glass (PBG) fiber when immersed in SBF. The light intensity remained constant for the first 48h after which a decrease with three distinct slopes was observed: the first decrease between 48 and 200h of immersion could be correlated to the formation of the Ca-P layer at the fiber surface. After this a faster decrease in light transmission was observed from 200 to ~425h in SBF. SEM analysis suggested that after 200h, the surface of the fiber was fully covered by a thin Ca-P layer which is likely to scatter light. For immersion times longer than ~425h, the thickness of the Ca-P layer increased and thus acted as a barrier to the dissolution process limiting further reduction in light transmission. The tracking of light transmission through the PBG fiber allowed monitoring of the fiber dissolution in vitro. These results are essential in developing new bioactive fiber sensors that can be used to monitor bioresponse in situ. Copyright © 2014 Elsevier B.V. All rights reserved.

Salicylyl Fluorene Derivatives as Fluorescent Sensors for Cu(II) Ions.

PubMed

Khaokeaw, Chenwit; Sukwattanasinitt, Mongkol; Rashatasakhon, Paitoon

2016-03-01

Two derivatives of fluorene containing salicylic acid groups are successfully synthesized by palladium-catalyzed coupling reactions and subsequent hydrolysis of salicylate esters. The compounds are characterized by various spectroscopic methods. In phosphate buffer (pH 8.0) solutions, these compounds are well soluble. They show maximum absorption wavelengths in the range of 304-330 nm and exhibit maximum emission wavelength around 420 and 430 nm with the quantum yields of 2.7 and 4.4 %, respectively. The compound with alkynyl salicylate groups (2) exhibits a selective fluorescence quenching towards Cu(II) and Fe(II) with a relatively similar sensitivity. The selectivity favoring Cu(II) over Fe(II) and other metal ions can be achieved upon the addition of 30 μM Triton X-100. The Cu(II) detection limit in solution phase is 1.47 ppb. The fluorescence signal recovery upon the addition of EDTA indicate a reversible complexation between 2 and Cu(II) ion. Fabrication of 2 on filter paper using a 50 μM solution in THF affords a naked-eye detection for Cu(II) and Fe(II) in aqueous media at picomole level.

Solubilization of ibuprofen with β-cyclodextrin derivatives: energetic and structural studies.

PubMed

di Cagno, Massimiliano; Stein, Paul C; Skalko-Basnet, Nataša; Brandl, Martin; Bauer-Brandl, Annette

2011-06-01

The aim of this work was to investigate the complexation of ibuprofen as model drug with various β-cyclodextrins (native β-cyclodextrin, hydroxypropyl-β-cyclodextrin with two different molar degrees of substitution, and methyl-β-cyclodextrin). Solutions of the commercially available β-cyclodextrins were prepared in phosphate buffer (73mM). The pH value was adjusted to 7.4 and the solutions were isotonized with NaCl. A solution of ibuprofen was prepared in the same way. A thermal activity monitor was used for isothermal titration calorimetry (ITC). (1)H NMR analysis was employed to investigate the structures of the complexes. ITC analysis showed that each type of β-cyclodextrin had its characteristic values of both enthalpy and mass equilibrium constant for the complexation processes with the drug molecules. (1)H NMR spectroscopy of the complexes showed through significant differences in chemical shifts that the physical interaction between the cyclodextrins and ibuprofen molecules were also different, probably due to different three-dimensional arrangements of ibuprofen in the cyclodextrin cavity, induced by the different substituents bonded to the glucose rings. These differences were connected to the thermodynamic parameters of the complexes. Copyright © 2011 Elsevier B.V. All rights reserved.

Determination of 10 sulfonamide residues in meat samples by liquid chromatography with ultraviolet detection.

PubMed

Di Sabatino, Marcello; Di Pietra, Anna Maria; Benfenati, Luigi; Di Simone, Bruno

2007-01-01

A liquid chromatography (LC) method is described for the simultaneous determination of 10 commonly used sulfonamide drug residues in meat. The 10 sulfonamide drugs of interest were sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamethizole, sulfamonomethoxine, sulfachloropyridazine, sulfadoxine, sulfadimethoxine, and sulfaquinoxaline. The residues were extracted with acetone-chloroform (1 + 1). Sulfonamides were quantitatively retained in the extracting solution and afterwards eluted from a cation-exchanger solid-phase extraction cartridge with a solution of methanol-aqueous ammonia. The solution was dried, reconstituted with 5 mL methanol and filtered before analysis by LC-ultraviolet using a C18 column with a mobile phase gradient of potassium dihydrogen phosphate buffer, pH 2.5, and methanol-acetonitrile (30 + 70, v/v). The method was applied to cattle, swine, chicken, and sheep muscle tissues. The validation was performed with a fortified cattle meat sample at level of 100 ppb, which is the administrative maximum residue limit for sulfonamides in the European Union. The limit of quantitation for all sulfonamides was between 3 and 14 ppb. Recovery was evaluated for different meat matrixes. The mean recovery values were between 66.3% for pork meat samples and 71.5% for cattle meat samples.

ssDNA degradation along capillary electrophoresis process using a Tris buffer.

PubMed

Ric, Audrey; Ong-Meang, Varravaddheay; Poinsot, Verena; Martins-Froment, Nathalie; Chauvet, Fabien; Boutonnet, Audrey; Ginot, Frédéric; Ecochard, Vincent; Paquereau, Laurent; Couderc, François

2017-06-01

Tris-Acetate buffer is currently used in the selection and the characterization of ssDNA by capillary electrophoresis (CE). By applying high voltage, the migration of ionic species into the capillary generates a current that induces water electrolysis. This phenomenon is followed by the modification of the pH and the production of Tris derivatives. By injecting ten times by capillary electrophoresis ssDNA (50 nM), the whole oligonucleotide was degraded. In this paper, we will show that the Tris buffer in the running vials is modified along the electrophoretic process by electrochemical reactions. We also observed that the composition of the metal ions changes in the running buffer vials. This phenomenon, never described in CE, is important for fluorescent ssDNA analysis using Tris buffer. The oligonucleotides are degraded by electrochemically synthesized species (present in the running Tris vials) until it disappears, even if the separation buffer in the capillary is clean. To address these issues, we propose to use a sodium phosphate buffer that we demonstrate to be electrochemically inactive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioactive calcium phosphate–based glasses and ceramics and their biomedical applications: A review

PubMed Central

Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

2017-01-01

An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented. PMID:28794848

Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis

PubMed Central

Mathew, Anju; Reddy, N. Venugopal; Sugumaran, D. K.; Peter, Joby; Shameer, M.; Dauravu, Liju Marcely

2013-01-01

Background: Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved. Aims: The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel. Design: An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis. Materials and Methods: A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37°C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry. Statistical Analysis: An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values. Results: Significant differences were found between the control group and the test groups (P < 0.001). Conclusions: Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone. PMID:24015004

Characteristics of Zinc Phosphate Coating Activated by Different Concentrations of Nickel Acetate Solution

NASA Astrophysics Data System (ADS)

Abdalla, Khalid; Zuhailawati, H.; Rahmat, Azmi; Azizan, A.

2017-02-01

Activation pretreatment with nickel acetate solution at various concentrations was performed prior to the phosphating step to enhance the corrosion resistance of carbon steel substrates. The activation solution was studied over various concentrations: 10, 50, and 100 g/L. The effects of these concentrations on surface characteristics and microstructural evolution of the coated samples were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The electrochemical behavior was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion test in a 3.5 pct NaCl solution. Significant increases in the nucleation sites and surface coverage of zinc phosphate coating were observed as the concentration of activation solution reached 50 g/L. The electrochemical analysis revealed that the activation treatment with 50 g/L nickel acetate solution significantly improved the protection ability of the zinc phosphate coating. The corrosion current density of activated phosphate coating with 50 g/L was reduced by 64.64 and 13.22 pct, compared to the coatings obtained with activation solutions of 10 and 100 g/L, respectively.

Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

DOEpatents

Joshi, Ashok V [Salt Lake City, UT; Balagopal, Shekar [Sandy, UT; Pendelton, Justin [Salt Lake City, UT

2011-12-13

Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

An SFG study of interfacial amino acids at the hydrophilic SiO2 and hydrophobic deuterated polystyrene surfaces.

PubMed

Holinga, George J; York, Roger L; Onorato, Robert M; Thompson, Christopher M; Webb, Nic E; Yoon, Alfred P; Somorjai, Gabor A

2011-04-27

Sum frequency generation (SFG) vibrational spectroscopy was employed to characterize the interfacial structure of eight individual amino acids--L-phenylalanine, L-leucine, glycine, L-lysine, L-arginine, L-cysteine, L-alanine, and L-proline--in aqueous solution adsorbed at model hydrophilic and hydrophobic surfaces. Specifically, SFG vibrational spectra were obtained for the amino acids at the solid-liquid interface between both hydrophobic d(8)-polystyrene (d(8)-PS) and SiO(2) model surfaces and phosphate buffered saline (PBS) at pH 7.4. At the hydrophobic d(8)-PS surface, seven of the amino acids solutions investigated showed clear and identifiable C-H vibrational modes, with the exception being l-alanine. In the SFG spectra obtained at the hydrophilic SiO(2) surface, no C-H vibrational modes were observed from any of the amino acids studied. However, it was confirmed by quartz crystal microbalance that amino acids do adsorb to the SiO(2) interface, and the amino acid solutions were found to have a detectable and widely varying influence on the magnitude of SFG signal from water at the SiO(2)/PBS interface. This study provides the first known SFG spectra of several individual amino acids in aqueous solution at the solid-liquid interface and under physiological conditions.

Tribological and Rheological Properties of a Synovial Fluid Model

NASA Astrophysics Data System (ADS)

Klossner, Rebecca; Liang, Jing; Krause, Wendy

2010-03-01

Hyaluronic acid (HA) and the plasma proteins, albumin and globulins, are the most abundant macromolecules in synovial fluid, the fluid that lubricates freely moving joints. In previous studies, bovine synovial fluid, a synovial fluid model (SFM) and albumin in phosphate buffered saline (PBS) were observed to be rheopectic---viscosity increases over time under constant shear. Additionally, steady shear experiments have a strong shear history dependence in protein-containing solutions, whereas samples of HA in PBS behaved as a ``typical'' polyelectrolyte. The observed rheopexy and shear history dependence are indicative of structure building in solution, which is most likely caused by protein aggregation. The tribology of the SFM was also investigated using nanoindenter-based scratch tests. The coefficient of frictions (μ) between the diamond nanoindenter tip and a polyethylene surface was measured in the presence of the SFM and solutions with varied protein and HA concentrations. The lowest μ is observed in the SFM, which most closely mimics a healthy joint. Finally, an anti-inflammatory drug, hydroxychloroquine, was shown to inhibit protein interactions in the SFM in rheological studies, and thus the tribological response was examined. We hypothesize that the rheopectic behavior is important in lubrication regimes and therefore, the rheological and tribological properties of these solutions will be correlated.

Sub-lethal heat treatment affects the tolerance of Cronobacter sakazakii BCRC 13988 to various organic acids, simulated gastric juice and bile solution.

PubMed

Hsiao, Wan-Ling; Ho, Wei-Li; Chou, Cheng-Chun

2010-12-15

Cronobacter spp., formerly Enterobacter sakazakii, are considered emerging opportunistic pathogens and the etiological agent of life-threatening bacterial infections in infants. In the present study, C. sakazakii BCRC 13988 was first subjected to sub-lethal heat treatment at 47°C for 15min. Survival rates of the heat-shocked and non-shocked C. sakazakii cells in phosphate buffer solution (PBS, pH 4.0) containing organic acids (e.g. acetic, propionic, citric, lactic or tartaric acid), simulated gastric juice (pH 2.0-4.0), and bile solution (0.5 and 2.0%) were examined. Results revealed that sub-lethal heat treatment enhanced the test organism's tolerance to organic acids, although the extent of increased acid tolerance varied with the organic acid examined. Compared with the control cells, heat-shocked C. sakazakii cells after 120-min of exposure, exhibited the largest increase in tolerance in the lactic acid-containing PBS. Furthermore, although heat shock did not affect the behavior of C. sakazakii in bile solution, it increased the test organism's survival when exposed to simulated gastric juice with a pH of 3.0-4.0. Copyright © 2010. Published by Elsevier B.V.

Hormone-Dependence of Sarin Lethality in Rats: Sex Differences and Stage of the Estrous Cycle

DTIC Science & Technology

2015-06-12

that causes numerous physiological events including miosis, salivation , respiratory failure, tremors, seizures, and death. Treatment regimens that...into 96-well plates. The reactions were initiated by the addition of 290 μL of 50 mM sodium phosphate buffer ( pH 8.0) containing one of the following...buffer containing 50mMHEPES pH 7.4 in a total volume of 280 μL. Treat- ed samples were loaded into a 96-microtiter plate well, and the reaction was

A Core Facility for the Study of Neurotoxins of Biological Origin

DTIC Science & Technology

1990-06-15

toxicity of 5 x 10-8 MLD/mg protein. Sodium 125 Iodine and the Bolton-Hunter Reagent - 1251odine were purchased from Amersham. Chloramine- T , glycine...tyrosine and all salts and buffers were from Sigma Chemical Co. and Fisher. Iodination procedures. The chloramine- T method was used essentially as...previously described. Tetanus toxin (100 ig) in sodium phosphate buffer (100 mM, pH 7.4) was mixed with chloramine- T (0.5 mM) and Na 1251 (1 mCi) for 30

Reverse Micelle Mediated synthesis of Calcium Phosphate Nanocarriers for Controlled Release of Bovine Serum Albumin (BSA)

PubMed Central

Dasgupta, Sudip; Bandyopadhyay, Amit; Bose, Susmita

2010-01-01

Calcium phosphate (CaP) nanoparticle with calcium to phosphorus (Ca:P) molar ratio of 1.5:1 were synthesized using reverse micro emulsion. Ca(NO3)2.4H2O and H3PO4 were used as aqueous phase, cyclohexane as organic phase, and poly(oxyethylene)12 nonylphenol ether (NP-12) as surfactant. Depending on calcination temperature between 600 and 800 °C, CaP nanoparticle showed different phases calcium deficient hydroxyapatite (CDHA) and β-tricalcium phosphate (β-TCP), particle size between 48 and 69 nm, the BET specific average surface area between 73 m2/g and 57 m2/g. Bovine serum albumin (BSA) was used as a model protein to study loading and release behavior. Adsorptive property of BSA was investigated with the change in BET surface area of these nanoparticle and the pH of the suspension. At pH 7.5, maximum amount of BSA was adsorbed onto CaP nanoparticle. The release kinetics of BSA showed a gradual time dependent increase at pH 4.0 and 6.0 buffer solutions. However, the amount of released protein was significantly smaller at pH 7.2. BSA release rate also varied depending on the presence of different phases of CaPs in the system, β-TCP or CDHA. These results suggest that BSA protein release rate can be controlled by changing particle size, surface area and phase composition of CaP nanocarriers. PMID:19435617

Micropore-induced Capillarity Enhances Bone Distribution in vivo in Biphasic Calcium Phosphate Scaffolds

PubMed Central

Rustom, Laurence E.; Boudou, Thomas; Lou, Siyu; Pignot-Paintrand, Isabelle; Nemke, Brett W.; Lu, Yan; Markel, Mark D.; Picart, Catherine; Wagoner Johnson, Amy J.

2016-01-01

The increasing demand for bone repair solutions calls for the development of efficacious bone scaffolds. Biphasic calcium phosphate (BCP) scaffolds with both macropores and micropores (MP) have improved healing compared to those with macropores and no micropores (NMP), but the role of micropores is unclear. Here, we evaluate capillarity induced by micropores as a mechanism that can affect bone growth in vivo. Three groups of cylindrical scaffolds were implanted in pig mandibles for three weeks: MP were implanted either dry (MP-Dry), or after submersion in phosphate buffered saline, which fills pores with fluid and therefore suppresses micropore-induced capillarity (MP-Wet); NMP were implanted dry. The amount and distribution of bone in the scaffolds were quantified using micro-computed tomography. MP-Dry had a more homogeneous bone distribution than MP-Wet, although the average bone volume fraction, BVF¯, was not significantly different for these two groups (0.45±0.03 and 0.37±0.03, respectively). There was no significant difference in the radial bone distribution of NMP and MP-Wet, but the BVF¯ of NMP was significantly lower among the three groups (0.25±0.02). These results suggest that micropore-induced capillarity enhances bone regeneration by improving the homogeneity of bone distribution in BCP scaffolds. The explicit design and use of capillarity in bone scaffolds may lead to more effective treatments of large and complex bone defects. PMID:27544807

[Isolation and determination of the seeds of Pachyrrhizus errosus protein by high performance gel filtration chromatography (GFC)].

PubMed

Wu, H; Hao, B; Tang, G; Lin, Y

1997-03-01

From the seeds of Pachyrrhizus errosus, three protein constituents, namel PE1, PE2 and PE3, have been isolated and purified by extraction with 5mmol/L phosphate saline (0.9% NaCl) buffer (PB) at pH 7.2, and S-Sepharose Fast Flow Column (2.6cm x 15cm) chromatography which eluted with 5mmol/L phosphate buffer (pH 7.0) containing 1mmol/L NaCl. Three proteins were burther separated on two connected Protein-Pak 60+Protein-Pak 125 [7.5mm x 39cm, 10microm] columns with mobile phase of 0.2mol/L phosphate buffer (pH 6.5). The flow rate was kept constant at 0.8mL/min by YSB-2 type high press pump. The effluent was monitored at a wavelength of 280nm on photodiode array detector. These three proteins are proved to be homogeneous by SDS-PAGE, IEF and HPGFC experiments, and all present the typical absorption spectra in ultraviolet region. The moleculer weights of the three proteins are approxiamtely 33000D, 14500D and 14000D respectively by SDS-PAGE. But as using HPGFC analysis, the MW value of PE2 is 28000D. This indicates PE2 may be composed of two chains joined by disulfide bond, which is further proved from the latter amino acid composition analysis. The isoelectric points of three proteins are 4.5, 6.5 and 7.5 respectively by using IEF. The amion acids compositions of the three proteins were determined with OPA post-column derivatization/fluorescence detection.

Two new glucose 6-phosphate dehydrogenase variants associated with congenital nonspherocytic hemolytic anemia found in Japan: GD(-) Tokushima and GD(-) Tokyo.

PubMed

Miwa, S; Ono, J; Nakashima, K; Abe, S; Kageoka, T

1976-01-01

Two new variants of glucose 6-phosphate dehydrogenase (G6PD) deficiency associated with chronic nonspherocytic hemolytic anemia were discovered in Japan. Gd(-) Tokushima was found in a 17-years-old male whose erythrocytes contained 4.4% of normal enzyme activity. Partially purified enzyme revealed a main band of normal electrophoretic mobility with additional two minor bands of different mobility; normal Km G6P, and Km NADP five-to sixfold higher than normal; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; marked thermal instability; a normal pH curve; and normal Ki NADPH. The hemolytic anemia was moderate to severe. Gd(-) Tokyo was characterized from a 15-year-old male who had chronic nonspherocytic hemolytic anemia of mild degree. The erythrocytes contained 3% of normal enzyme activity, and partially purified enzyme revealed slow electrophoretic mobility (90% of normal for both a tris-hydrochloride buffer system and a tris-EDTA-borate buffer system, and 70% of normal for a phosphate buffer system); normal Km G6P and Km NADP; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; greatly increased thermal instability; a normal pH curve; and normal Ki NADPH. These two variants are clearly different from hitherto described G6PD variants, including the Japanese variants Gd(-) Heian and Gd(-) Kyoto. The mothers of both Gd(-) Tokushima and Gd(-) Tokoyo were found to be heterozygote by an ascorbate-cyanide test.

Development and Optimization of HPLC Analysis of Metronidazole, Diloxanide, Spiramycin and Cliquinol in Pharmaceutical Dosage Forms Using Experimental Design.

PubMed

Elkhoudary, Mahmoud M; Abdel Salam, Randa A; Hadad, Ghada M

2016-11-01

A new simple, sensitive, rapid and accurate gradient reversed-phase high-performance liquid chromatography with photodiode array detector (RP-HPLC-DAD) was developed and validated for simultaneous analysis of Metronidazole (MNZ), Spiramycin (SPY), Diloxanidefuroate (DIX) and Cliquinol (CLQ) using statistical experimental design. Initially, a resolution V fractional factorial design was used in order to screen five independent factors: the column temperature (°C), pH, phosphate buffer concentration (mM), flow rate (ml/min) and the initial fraction of mobile phase B (%). pH, flow rate and initial fraction of mobile phase B were identified as significant, using analysis of variance. The optimum conditions of separation determined with the aid of central composite design were: (1) initial mobile phase concentration: phosphate buffer/methanol (50/50, v/v), (2) phosphate buffer concentration (50 mM), (3) pH (4.72), (4) column temperature 30°C and (5) mobile phase flow rate (0.8 ml min -1 ). Excellent linearity was observed for all of the standard calibration curves, and the correlation coefficients were above 0.9999. Limits of detection for all of the analyzed compounds ranged between 0.02 and 0.11 μg ml -1 ; limits of quantitation ranged between 0.06 and 0.33 μg ml -1 The proposed method showed good prediction ability. The optimized method was validated according to ICH guidelines. Three commercially available tablets were analyzed showing good % recovery and %RSD. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Occurrence of 1-glyceryl-1-myo-inosityl phosphate in hyperthermophiles.

PubMed

Lamosa, Pedro; Gonçalves, Luís G; Rodrigues, Marta V; Martins, Lígia O; Raven, Neil D H; Santos, Helena

2006-09-01

The accumulation of compatible solutes was studied in the hyperthermophilic bacterium Aquifex pyrophilus as a function of the temperature and the NaCl concentration of the growth medium. Nuclear magnetic resonance analysis of cell extracts revealed the presence of alpha- and beta-glutamate, di-mannosyl-di-myo-inositol phosphate, di-myo-inositol phosphate, and an additional compound here identified as 1-glyceryl-1-myo-inosityl phosphate. All solutes accumulated by A. pyrophilus are negatively charged at physiological pH. The intracellular levels of di-myo-inositol phosphate increased in response to supraoptimal growth temperature, while alpha- and beta-glutamate accumulated in response to osmotic stress, especially at growth temperatures below the optimum. The newly discovered compound, 1-glyceryl-1-myo-inosityl phosphate, appears to play a double role in osmo- and thermoprotection, since its intracellular pool increased primarily in response to a combination of osmotic and heat stresses. This work also uncovered the nature of the unknown compound, previously detected in Archaeoglobus fulgidus (L. O. Martins et al., Appl. Environ. Microbiol. 63:896-902, 1997). The curious structural relationship between diglycerol phosphate (found only in Archaeoglobus species), di-myo-inositol phosphate (a canonical solute of hyperthermophiles), and the newly identified solute is highlighted. This is the first report on the occurrence of 1-glyceryl-1-myo-inosityl phosphate in living systems.

On-line pH modification of carbonate eluents using an electrolytic potassium hydroxide generator for ion chromatography.

PubMed

Novic, Milko; Liu, Yan; Avdalovic, Nebojsa; Pihlar, Boris

2002-05-31

Classical gradient elution, based on the application of a gradient pump used for mixing two or more prepared eluent components in pre-determined concentrations, was replaced by a chromatography system equipped with an isocratic pump and an electrolytic KOH generator. The isocratic pump delivered a constant concentration eluent composed of pure hydrogencarbonate solution. Carbonate ions, the main component of carbonate/hydrogencarbonate-based eluents, were formed by titration of hydrogencarbonate with KOH formed on-line in the electrolytic KOH generator. By changing the concentration of electrolytically-generated KOH, the eluent composition could be changed from pure hydrogencarbonate to a carbonate/hydrogencarbonate buffer, and finally to a carbonate/hydroxide-based eluent. The described system was tested to achieve pH-based changes of retention behavior of phosphate under constant inflow eluent composition conditions.

The Bactericidal Effect of Shock Waves

NASA Astrophysics Data System (ADS)

Leighs, James; Appleby-Thomas, Gareth; Wood, David; Goff, Michael; Hameed, Amer; Hazell, Paul

2013-06-01

There are a variety of theories relating to the origins of life on our home planet, some of which discuss the possibility that life may have been spread via inter-planetary impacts. There have been a number of investigations into the ability of life to withstand the likely conditions generated by asteroid impact (both contained in the impactor and buried beneath the planet surface). Previously published data regarding the ability of bacteria to survive such applied shock waves has produced conflicting conclusions. The work presented here used an established technique, in combination with a single stage gas gun to shock load and subsequently recover Escherichia coli populations suspended in a phosphate buffered saline solution. Peak pressure across the sample region was calculated via numerical modelling, validated via Heterodyne velocimetry measurements. Survival data against peak sample pressure for recovered samples is presented alongside control tests.