Science.gov

Sample records for achieve controlled release

  1. Method of achieving the controlled release of thermonuclear energy

    DOEpatents

    Brueckner, Keith A.

    1986-01-01

    A method of achieving the controlled release of thermonuclear energy by illuminating a minute, solid density, hollow shell of a mixture of material such as deuterium and tritium with a high intensity, uniformly converging laser wave to effect an extremely rapid build-up of energy in inwardly traveling shock waves to implode the shell creating thermonuclear conditions causing a reaction of deuterons and tritons and a resultant high energy thermonuclear burn. Utilizing the resulting energy as a thermal source and to breed tritium or plutonium. The invention also contemplates a laser source wherein the flux level is increased with time to reduce the initial shock heating of fuel and provide maximum compression after implosion; and, in addition, computations and an equation are provided to enable the selection of a design having a high degree of stability and a dependable fusion performance by establishing a proper relationship between the laser energy input and the size and character of the selected material for the fusion capsule.

  2. General Strategy to Introduce pH-Induced Allostery in DNA-Based Receptors to Achieve Controlled Release of Ligands.

    PubMed

    Porchetta, Alessandro; Idili, Andrea; Vallée-Bélisle, Alexis; Ricci, Francesco

    2015-07-01

    Inspired by naturally occurring pH-regulated receptors, here we propose a rational approach to introduce pH-induced allostery into a wide range of DNA-based receptors. To demonstrate this we re-engineered two model DNA-based probes, a molecular beacon and a cocaine-binding aptamer, by introducing in their sequence a pH-dependent domain. We demonstrate here that we can finely tune the affinity of these model receptors and control the load/release of their specific target molecule by a simple pH change. PMID:26053894

  3. Controlled Release Applications of Organometals.

    ERIC Educational Resources Information Center

    Thayer, John S.

    1981-01-01

    Reviews two classes of controlled release organometals: (1) distributional, to distribute bioactive materials to control a certain target organism; and (2) protective, to protect surface or interior of some structure from attach by organisms. Specific examples are given including a discussion of controlled release for schistosomiasis. (SK)

  4. Optogenetic control of ATP release

    NASA Astrophysics Data System (ADS)

    Lewis, Matthew A.; Joshi, Bipin; Gu, Ling; Feranchak, Andrew; Mohanty, Samarendra K.

    2013-03-01

    Controlled release of ATP can be used for understanding extracellular purinergic signaling. While coarse mechanical forces and hypotonic stimulation have been utilized in the past to initiate ATP release from cells, these methods are neither spatially accurate nor temporally precise. Further, these methods cannot be utilized in a highly effective cell-specific manner. To mitigate the uncertainties regarding cellular-specificity and spatio-temporal release of ATP, we herein demonstrate use of optogenetics for ATP release. ATP release in response to optogenetic stimulation was monitored by Luciferin-Luciferase assay (North American firefly, photinus pyralis) using luminometer as well as mesoscopic bioluminescence imaging. Our result demonstrates repetitive release of ATP subsequent to optogenetic stimulation. It is thus feasible that purinergic signaling can be directly detected via imaging if the stimulus can be confined to single cell or in a spatially-defined group of cells. This study opens up new avenue to interrogate the mechanisms of purinergic signaling.

  5. Controlled Release from Recombinant Polymers

    PubMed Central

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  6. Encapsulation of ketoprofen for controlled drug release.

    PubMed

    Arida, Adi I; Al-Tabakha, Moawia M

    2007-04-01

    Ketoprofen particles were encapsulated with polyions and gelatin to control the release of the drug in aqueous solutions. Charged linear polyions and gelatin were alternatively deposited on 6 microm drug microcrystals through layer-by-layer (LbL) assembly. Sequential layers of poly(dimethyldiallyl ammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS) were followed by adsorption of two to six gelatin/PSS bilayers with corresponding capsule wall thicknesses ranging from 41 to 111 nm. The release of Ketoprofen from the coated microparticles was measured in aqueous solutions of pH 1.4, 4.1, and 7.4. The release rate has changed at these different pH values. At pH 7.4 the release rate of Ketoprofen from the encapsulated particles was less by 107 times compared to uncoated Ketoprofen. The results provide a method of achieving prolonged drug release through self-assembly of polymeric shells on drug crystals. PMID:17098404

  7. Controlled release liquid dosage formulation

    DOEpatents

    Benton, Ben F.; Gardner, David L.

    1989-01-01

    A liquid dual coated dosage formulation sustained release pharmaceutic having substantial shelf life prior to ingestion is disclosed. A dual coating is applied over controlled release cores to form dosage forms and the coatings comprise fats melting at less than approximately 101.degree. F. overcoated with cellulose acetate phthalate or zein. The dual coated dosage forms are dispersed in a sugar based acidic liquid carrier such as high fructose corn syrup and display a shelf life of up to approximately at least 45 days while still retaining their release profiles following ingestion. Cellulose acetate phthalate coated dosage form cores can in addition be dispersed in aqueous liquids of pH <5.

  8. Controlling protein release using biodegradable microparticles

    NASA Astrophysics Data System (ADS)

    Kline, Benjamin Patrick

    Research in the field of protein therapeutics has exploded over the past decade and continues to grow in both academia and in industry. Protein drugs have advantages of being highly specific and highly active making them coveted targets for high profile disease states like cancer and multiple sclerosis. Unfortunately, their many advantages are complemented by their obstacles. Because proteins are highly active and highly specific, the window between efficacy and toxicity is very narrow and drug development can be long and arduous. In addition, protein activity is dependent on its specific folding conformation that is easily disrupted by a variety of development processes. This research aimed to identify microparticle formulations to control protein release and also to determine which formulation parameters affected burst release, encapsulation, and steady-state release the most. It was found that polymer type and composition were two of the most important factors. Long-term controlled release of bovine serum albumin (BSA) was achieved as well as a wide variety of release profiles. A method was identified for micronizing protein at low cost to retain activity and coacervation was evaluated as a method for preparing protein loaded microspheres. This research provides a basis from which researchers can create better controlled release formulations for future protein therapeutics.

  9. Tailoring nanoarchitectonics to control the release profile of payloads.

    PubMed

    Jiang, Shuai; Lv, Liping; Li, Qifeng; Wang, Junwei; Landfester, Katharina; Crespy, Daniel

    2016-06-01

    We demonstrate here that the control over the release rate of payloads and on the selectivity of the release can be achieved by designing nanomaterials with a hierarchical structure. Redox-responsive silica nanocapsules are first synthesized to allow for an accelerated release of the corrosion inhibitor 2-mercaptobenzothiazole as a payload upon chemical reduction and retarded release upon oxidation. In a second step, we embedded the nanocapsules into nanofibers by colloid-electrospinning, yielding a hierarchical composite structure. Remarkably, the encapsulation of the nanocapsules in the fibers provides two decisive advantages that are a higher selectivity of the release and a higher control over the release rate of payloads. PMID:27198762

  10. Tailoring nanoarchitectonics to control the release profile of payloads

    NASA Astrophysics Data System (ADS)

    Jiang, Shuai; Lv, Liping; Li, Qifeng; Wang, Junwei; Landfester, Katharina; Crespy, Daniel

    2016-06-01

    We demonstrate here that the control over the release rate of payloads and on the selectivity of the release can be achieved by designing nanomaterials with a hierarchical structure. Redox-responsive silica nanocapsules are first synthesized to allow for an accelerated release of the corrosion inhibitor 2-mercaptobenzothiazole as a payload upon chemical reduction and retarded release upon oxidation. In a second step, we embedded the nanocapsules into nanofibers by colloid-electrospinning, yielding a hierarchical composite structure. Remarkably, the encapsulation of the nanocapsules in the fibers provides two decisive advantages that are a higher selectivity of the release and a higher control over the release rate of payloads.We demonstrate here that the control over the release rate of payloads and on the selectivity of the release can be achieved by designing nanomaterials with a hierarchical structure. Redox-responsive silica nanocapsules are first synthesized to allow for an accelerated release of the corrosion inhibitor 2-mercaptobenzothiazole as a payload upon chemical reduction and retarded release upon oxidation. In a second step, we embedded the nanocapsules into nanofibers by colloid-electrospinning, yielding a hierarchical composite structure. Remarkably, the encapsulation of the nanocapsules in the fibers provides two decisive advantages that are a higher selectivity of the release and a higher control over the release rate of payloads. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00917d

  11. Controlled Drug Release from Pharmaceutical Nanocarriers

    PubMed Central

    Lee, Jinhyun Hannah; Yeo, Yoon

    2014-01-01

    Nanocarriers providing spatiotemporal control of drug release contribute to reducing toxicity and improving therapeutic efficacy of a drug. On the other hand, nanocarriers face unique challenges in controlling drug release kinetics, due to the large surface area per volume ratio and the short diffusion distance. To develop nanocarriers with desirable release kinetics for target applications, it is important to understand the mechanisms by which a carrier retains and releases a drug, the effects of composition and morphology of the carrier on the drug release kinetics, and current techniques for preparation and modification of nanocarriers. This review provides an overview of drug release mechanisms and various nanocarriers with a specific emphasis on approaches to control the drug release kinetics. PMID:25684779

  12. BIOMONITORING TO ACHIEVE CONTROL OF TOXIC EFFLUENTS

    EPA Science Inventory

    This 48 - page Technology Transfer Report provides a case study of how water quality-based toxicity control procedures can be combined with chemical analyses and biological stream surveys to achieve more effective water pollution control. t describes how regulatory agencies used ...

  13. 3D hybrid wound devices for spatiotemporally controlled release kinetics.

    PubMed

    Ozbolat, Ibrahim T; Koc, Bahattin

    2012-12-01

    This paper presents localized and temporal control of release kinetics over 3-dimensional (3D) hybrid wound devices to improve wound-healing process. Imaging study is performed to extract wound bed geometry in 3D. Non-Uniform Rational B-Splines (NURBS) based surface lofting is applied to generate functionally graded regions. Diffusion-based release kinetics model is developed to predict time-based release of loaded modifiers for functionally graded regions. Multi-chamber single nozzle solid freeform dispensing system is used to fabricate wound devices with controlled dispensing concentration. Spatiotemporal control of biological modifiers thus enables a way to achieve target delivery to improve wound healing. PMID:22672934

  14. Design of an actively controlled snow ski release binding.

    PubMed

    Hull, M L; Allen, K W

    1981-08-01

    A new electronic ski binding has been designed which may better protect skiers from lower extremity injuries. A four-step procedure for developing binding release criteria aimed at preventing specific injuries is outlined. Using simplified biomechanical models, the release criteria for tibia fracture in both torsion and flexion are derived. A binding design which embodies the derived release criteria is described. The binding consists of three subsystems: 1) a dynamometer, 2) an analog computer controller, and 3) an electromechanical release mechanism. The strain gage dynamometer directly measures torsion and bending moments between the boot and ski. An analog computer controlled processes dynamometer signals. Dual release mode capability is achieved by parallel solution of differential equations which model the leg in both medial-lateral rotation and flexion. When the model solution reaches a critical value, the controller actuates the release mechanism. The release mechanism incorporates a unique closed circuit hydraulic system which rigidly locks the boot to the ski until release. Laboratory tests on a prototype confirm that the computer-controlled binding prevents inadvertent release under noninjurious high-magnitude, short-duration loads but releases before quasi-static loads reach injurious levels. PMID:7278190

  15. Achievements of schistosomiasis control in China.

    PubMed

    Yuan, Hongchang; Jiang, Qingwu; Zhao, Genming; He, Na

    2002-01-01

    The control of schistosomiasis has been spectacularly successful in terms of controlling endemicity and severity of the disease during the last 50 years. It can be categorized into two stages. From 1955 through 1980, the transmission-control strategy had been widely and successfully carried out. By the end of 1980, the epidemic of schistosomiasis was successfully circumscribed in certain core regions including areas at the middle and low reaches of the Yangtze River and some mountainous areas in Sichuan and Yunnan provinces, where control of schistosomiasis had been demonstrated to be very difficult to be sustained. Therefore, since 1980, schistosomiasis control in China has been modified to employ a stepwise strategy, based on which morbidity control has been given priorities and if possible transmission control has been pursued. However, since snail-ridden areas remain unchanged so far, reinfections occur frequently. This necessitates a maintenance phase to consolidate the achievements in the control of schistosomiasis. In the mean time, we are challenged with some environmental, social and economical changes in terms of controlling schistosomiasis. Successfully controlling schistosomiasis in China is still a long-term task but will be achieved without doubt along with the economic development and the promotion of living and cultural standard of people. PMID:12426618

  16. Oxycodone controlled release in cancer pain management.

    PubMed

    Biancofiore, Giuseppe

    2006-09-01

    Oral opioids are the treatment of choice for chronic cancer pain. Morphine is the strong opioid of choice for the treatment of moderate to severe cancer pain according to guidelines from the World Health Organization (WHO). This recommendation by the WHO was derived from availability, familiarity to clinicians, established effectiveness, simplicity of administration, and relative inexpensive cost. It was not based on proven therapeutic superiority over other options. Patients who experience inadequate pain relief or intolerable side effects with one opioid may often be successfully treated with another agent or with the same agent administered by a different route. Opioid rotation, or switching to an alternative opioid, helps some patients achieve better pain control with fewer associated adverse effects. Oxycodone is a mu-opioid receptor specific ligand, with clear agonist properties. It is an active potent opioid, which is in part a kappa-receptor agonist. Like morphine and other pure agonists, there is no known ceiling to the analgesic effects of oxycodone. The active metabolites of oxycodone (eg, oxymorphone) could be important in oxycodone-mediated analgesia. The main pharmacokinetic difference between oxycodone and morphine is in oral bioavailability. The bioavailability of oxycodone is >60% and the bioavailability of morphine is 20%. Controlled-release oxycodone is absorbed in a bi-exponential fashion. There is a rapid phase with a mean half-life of 37 min, accounting for 38% of the dose, and a slow phase with a half-life of 6.2 h, which accounts for the residual 62%. Oxycodone elimination is impaired by renal failure because there are both an increased volume of distribution and reduced clearance. A lot of studies prove that the efficacy of controlled-release oxycodone in cancer-pain control is at least the same as morphine, immediate-release oxycodone and hydromorphone. Its toxicity profile seems better than that of morphine. There are actually several

  17. Birth control - slow release methods

    MedlinePlus

    Contraception - hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring ... might want to consider a different birth control method. SKIN PATCH The skin patch is placed on ...

  18. Controlled drug release from hydrogel nanoparticle networks.

    PubMed

    Huang, Gang; Gao, Jun; Hu, Zhibing; St John, John V; Ponder, Bill C; Moro, Dan

    2004-02-10

    Monodisperse nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid (PNIPAM-co-AA) were synthesized. The close-packed PNIPAM-co-allylamine and PNIPAM-co-AA nanoparticles were converted to three-dimensional gel networks by covalently crosslinking neighboring particles at room temperature and neutral pH using glutaric dialdehyde and adipic acid dihydrazide, respectively. Controlled release studies were conducted using dextran markers of various molecular weights as model macromolecular drugs. Release was quantified under various physical conditions, including a range of temperatures and dextran molecular weights. Dextran, entrapped in cavities in the nanoparticle network, was released with a rate regulated by their molecular weights and cavity size. No release from a conventional bulk PNIPAM gel, with high crosslinking density, was observed. The rate of release from the PNIPAM-co-allylamine network was temperature-dependent, being much faster at room temperature than that at human body temperature. In contrast, release of low molecular weight dextrans from the PNIPAM-co-AA network showed a temperature-independent release profile. These nanoparticle networks have several advantages over conventional bulk gels for controlling the release of high molecular weight biomolecules. PMID:14744482

  19. Proceedings: Neurohormonal control of prolactin release.

    PubMed

    Deis, R P; Alonso, N; Vermouth, N T

    1973-01-01

    Neurohomonal control of prolactin release was studied in pseudopregnant and pregnant rats. Nembutal administered at 1300 hours on Day 3 of pseudopregnancy prevented prolactin release which normally occurred at 1700 hours of the same day. Antiestrogen administered the day before did not prevent prolactin release but ovariectomy did. Estrogen administered immediately after ovariectomy did not restore prolactin secretion; however, progesterone on Day 3 in the ovariectomized-estrogen treated induced an increase in prolactin at 1700 hours. Progesterone was capable of increasing prolactin release the first 5 days of pseudopregnancy but not Days 6-12 when prolactin values were low. A similar effect was seen the first 7 days of pregnancy. Progesterone, but not estrogen, modified prolactin values on Day 9 at 1700 hours. Ovariectomy on Day 19 of pregnancy induced prolactin release within 4 hours and persisted for 58 hours. Progesterone administration immediately after ovariectomy prevented prolactin release for a few hours. These results suggest that the regulation of prolactin release by the central nervous system depends on the circulating estrogen/progesterone ratio, since estrogen facilitated prolactin release when plasma progesterone was low and progesterone induced prolactin release when adequated levels of estrogen existed, but exerted an inhibitory action when estrogen was not present. PMID:4795042

  20. Malaria control: achievements, problems and strategies.

    PubMed

    Nájera, J A

    2001-06-01

    Even if history has not always been the Magistra vitae, Cicero expected it to be, it should provide, as Baas said, a mirror in which to observe and compare the past and present in order to draw therefrom well-grounded conclusions for the future. Based on this belief, this paper aims to provide an overview of the foundations and development of malaria control policies during the XX century. It presents an analysis of the conflicting tendencies which shaped the development of these policies and which appear to have oscillated between calls for frontal attack in an all-out campaign and calls for sustainable gains, even if slow. It discusses the various approaches to the control of malaria, their achievements and their limitations, not only to serve as a background to understand better the foundations of current policies, but also to prevent that simplistic generalisations may again lead to exaggerated expectations and disillusion. The first part of the paper is devoted to the development of malaria control during the first half of the century, characterised by the ups and downs in the reliance on mosquito control as the control measure applicable everywhere. The proliferation of "man-made-malaria", which accompanied the push for economic development in most of the endemic countries, spurred the need for control interventions and, while great successes were obtained in many specific projects, the general campaigns proposed by the enthusiasts of vector control faced increasing difficulties in their practical implementation in the field. Important events, which may be considered representative of this period are, on the campaign approach, the success of Gorgas in the Panama Canal, but also the failure of the Mian Mir project in India; while on the developmental approach, the Italian and Dutch schools of malariology, the Tennessee Valley and the development of malaria sanitation, included the so called species sanitation. The projection of these developments to a global

  1. Enriching the Hierarchical Model of Achievement Motivation: Autonomous and Controlling Reasons Underlying Achievement Goals

    ERIC Educational Resources Information Center

    Michou, Aikaterini; Vansteenkiste, Maarten; Mouratidis, Athanasios; Lens, Willy

    2014-01-01

    Background: The hierarchical model of achievement motivation presumes that achievement goals channel the achievement motives of need for achievement and fear of failure towards motivational outcomes. Yet, less is known whether autonomous and controlling reasons underlying the pursuit of achievement goals can serve as additional pathways between…

  2. Controlled release fertilizer workshop, 1991: Proceedings

    SciTech Connect

    Scheib, R.M.

    1991-11-01

    Over the last 20 years the Tennessee Valley Authority's National Fertilizer and Environmental Research Center (NFERC) has carried out a number of programs to develop controlled release fertilizers. They pioneered the development and commercialization of sulfur coated urea and conducted extensive research in an attempt to develop an economical synthesis for oxamide. In recent years there has developed an increasing interest in the environmental impact of fertilizers, particularly on the potential for ground water contamination by nitrate derived from fertilizer materials. In response to this interest NFERC's Chemical Research Department organized a five member Controlled Release Fertilizer (CRF) Team to reassess the potential for controlled release materials in agriculture with a view to minimizing any adverse environmental impact and increasing the efficiency of nutrient utilization by the crop. This workshop was part of that reassessment program. The workshop goals were: To determine the present status of CRF research, production and use; to assess the future needs of CRF producers and consumers; and to promote communication and exchange of information. To accomplish these goals the team invited speakers from across' the United States representing academics, experimental station researchers, fertilizer producers, environmentalists, and marketing experts to present papers.

  3. Controlled release fertilizer workshop, 1991: Proceedings

    SciTech Connect

    Scheib, R.M.

    1991-11-01

    Over the last 20 years the Tennessee Valley Authority`s National Fertilizer and Environmental Research Center (NFERC) has carried out a number of programs to develop controlled release fertilizers. They pioneered the development and commercialization of sulfur coated urea and conducted extensive research in an attempt to develop an economical synthesis for oxamide. In recent years there has developed an increasing interest in the environmental impact of fertilizers, particularly on the potential for ground water contamination by nitrate derived from fertilizer materials. In response to this interest NFERC`s Chemical Research Department organized a five member Controlled Release Fertilizer (CRF) Team to reassess the potential for controlled release materials in agriculture with a view to minimizing any adverse environmental impact and increasing the efficiency of nutrient utilization by the crop. This workshop was part of that reassessment program. The workshop goals were: To determine the present status of CRF research, production and use; to assess the future needs of CRF producers and consumers; and to promote communication and exchange of information. To accomplish these goals the team invited speakers from across` the United States representing academics, experimental station researchers, fertilizer producers, environmentalists, and marketing experts to present papers.

  4. Controlled Release Formulations of Auxinic Herbicides

    NASA Astrophysics Data System (ADS)

    Kowalski, Witold J.; Siłowiecki, Andrzej.; Romanowska, Iwona; Glazek, Mariola; Bajor, Justyna; Cieciwa, Katarzyna; Rychter, Piotr

    2013-04-01

    Controlled release formulations are applied extensively for the release of active ingredients such as plant protection agents and fertilizers in response to growing concern for ecological problems associated with increased use of plant protection chemicals required for intensive agricultural practices [1]. We synthesized oligomeric mixtures of (R,S)-3-hydroxy butyric acid chemically bonded with 2,4-D, Dicamba and MCPA herbicides (HBA) respectively, and determined their molecular structure and molecular weight dispersion by the size exclusion chromatography, proton magnetic resonance spectrometry and electro-spray ionization mass spectrometry. Further we carried out bioassays of herbicidal effectiveness of the HBA herbicides vs. series of dicotyledonous weeds and crop injury tests [2, 3, 4]. Field bioassays were accomplished according to the EPPO standards [5]. Groups of representative weeds (the development stages in the BCCH scale: 10 - 30) were selected as targets. Statistical variabilities were assessed by the Fisher LSD test for plants treated with the studied herbicides in form of HBA oligomers, the reference herbicides in form of dimethyl ammonium salts (DMA), and untreated plants. No statistically significant differences in the crop injuries caused by the HBA vs. the DMA reference formulation were observed. The effectiveness of the HBA herbicides was lower through the initial period (ca. 2 weeks) relative to the DMA salts, but a significant increase in the effectiveness of the HBA systems followed during the remaining fraction of each assay. After 6 weeks all observed efficiencies approached 100%. The death of weeds treated with the HBA herbicides was delayed when compared with the DMA reference herbicides. The delayed uptake observed for the HBA oligomers relative to the DMA salts was due to controlled release phenomena. In case of the DMA salts the total amount of active ingredients was available at the target site. By contrast, the amount of an active

  5. Electrosprayed nanoparticle delivery system for controlled release.

    PubMed

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan; Harker, Anthony

    2016-09-01

    This study utilises an electrohydrodynamic technique to prepare core-shell lipid nanoparticles with a tunable size and high active ingredient loading capacity, encapsulation efficiency and controlled release. Using stearic acid and ethylvanillin as model shell and active ingredients respectively, we identify the processing conditions and ratios of lipid:ethylvanillin required to form nanoparticles. Nanoparticles with a mean size ranging from 60 to 70nm at the rate of 1.37×10(9) nanoparticles per minute were prepared with different lipid:ethylvanillin ratios. The polydispersity index was ≈21% and the encapsulation efficiency ≈70%. It was found that the rate of ethylvanillin release was a function of the nanoparticle size, and lipid:ethylvanillin ratio. The internal structure of the lipid nanoparticles was studied by transmission electron microscopy which confirmed that the ethylvanillin was encapsulated within a stearic acid shell. Fourier transform infrared spectroscopy analysis indicated that the ethylvanillin had not been affected. Extensive analysis of the release of ethylvanillin was performed using several existing models and a new diffusive release model incorporating a tanh function. The results were consistent with a core-shell structure. PMID:27207047

  6. Electrospun cellular microenvironments: Understanding controlled release and scaffold structure.

    PubMed

    Szentivanyi, Andreas; Chakradeo, Tanmay; Zernetsch, Holger; Glasmacher, Birgit

    2011-04-30

    Electrospinning is a versatile technique in tissue engineering for the production of scaffolds. To guide tissue development, scaffolds must provide specific biochemical, structural and mechanical cues to cells and deliver them in a controlled fashion over time. Electrospun scaffold design thus includes aspects of both controlled release and structural cues. Controlled multicomponent and multiphasic drug delivery can be achieved by the careful application and combination of novel electrospinning techniques, i.e., emulsion and co-axial electrospinning. Drug distribution and polymer properties influence the resulting release kinetics. Pore size is far more relevant as a structural parameter than previously recognized. It enables cell proliferation and ingrowth, whereas fiber diameter predominantly influences cell fate. Both parameters can be exploited by combining multiple fiber types in the form of multifiber and multilayer scaffolds. Such scaffolds are required to reproduce more complex tissue structures. PMID:21145932

  7. The Longitudinal Effects of Achievement Goals and Perceived Control on University Student Achievement

    ERIC Educational Resources Information Center

    Daniels, Lia M.; Perry, Raymond P.; Stupnisky, Robert H.; Stewart, Tara L.; Newall, Nancy E. G.; Clifton, Rodney A.

    2014-01-01

    In the area of achievement motivation, students' beliefs pertaining to achievement goals and perceived control have separately guided a large amount theoretical and empirical research. However, limited research has considered the simultaneous effects of goals and control on achievement. The purpose of this study was to examine primary and…

  8. Injectable controlled release depots for large molecules

    PubMed Central

    Schwendeman, Steven P.; Shah, Ronak B.; Bailey, Brittany A.; Schwendeman, Anna S.

    2014-01-01

    Biodegradable, injectable depot formulations for long-term controlled drug release have improved therapy for a number of drug molecules and led to over a dozen highly successful pharmaceutical products. Until now, success has been limited to several small molecules and peptides, although remarkable improvements have been accomplished in some of these cases. For example, twice-a-year depot injections with leuprolide are available compared to the once-a-day injection of the solution dosage form. Injectable depots are typically prepared by encapsulation of the drug in poly(lactic-co-glycolic acid) (PLGA), a polymer that is used in children every day as a resorbable suture material, and therefore, highly biocompatible. PLGAs remain today as one of the few “real world” biodegradable synthetic biomaterials used in US FDA-approved parenteral long-acting-release (LAR) products. Despite their success, there remain critical barriers to the more widespread use of PLGA LAR products, particularly for delivery of more peptides and other large molecular drugs, namely proteins. In this review, we describe key concepts in the development of injectable PLGA controlled-release depots for peptides and proteins, and then use this information to identify key issues impeding greater widespread use of PLGA depots for this class of drugs. Finally, we examine important approaches, particularly those developed in our research laboratory, toward overcoming these barriers to advance commercial LAR development. PMID:24929039

  9. Homeostatic control of presynaptic neurotransmitter release.

    PubMed

    Davis, Graeme W; Müller, Martin

    2015-01-01

    It is well established that the active properties of nerve and muscle cells are stabilized by homeostatic signaling systems. In organisms ranging from Drosophila to humans, neurons restore baseline function in the continued presence of destabilizing perturbations by rebalancing ion channel expression, modifying neurotransmitter receptor surface expression and trafficking, and modulating neurotransmitter release. This review focuses on the homeostatic modulation of presynaptic neurotransmitter release, termed presynaptic homeostasis. First, we highlight criteria that can be used to define a process as being under homeostatic control. Next, we review the remarkable conservation of presynaptic homeostasis at the Drosophila, mouse, and human neuromuscular junctions and emerging parallels at synaptic connections in the mammalian central nervous system. We then highlight recent progress identifying cellular and molecular mechanisms. We conclude by reviewing emerging parallels between the mechanisms of homeostatic signaling and genetic links to neurological disease. PMID:25386989

  10. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    PubMed Central

    Zhou, Zijun; Du, Changwen; Li, Ting; Shen, Yazhen; Zhou, Jianmin

    2015-01-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse “L” curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was “S” curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies. PMID:26348791

  11. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer.

    PubMed

    Zhou, Zijun; Du, Changwen; Li, Ting; Shen, Yazhen; Zhou, Jianmin

    2015-01-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse "L" curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was "S" curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies. PMID:26348791

  12. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    NASA Astrophysics Data System (ADS)

    Zhou, Zijun; Du, Changwen; Li, Ting; Shen, Yazhen; Zhou, Jianmin

    2015-09-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse “L” curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was “S” curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies.

  13. Reversible morphology transitions of supramolecular polymer self-assemblies for switch-controlled drug release.

    PubMed

    Zhang, Haitao; Fan, Xiaodong; Suo, Rongtian; Li, Hui; Yang, Zhen; Zhang, Wanbin; Bai, Yang; Yao, Hao; Tian, Wei

    2015-10-28

    A novel method for switch-controlled drug release was developed through the reversible morphology transitions of supramolecular branched copolymer self-assemblies. The reversible transitions from vesicles to nanoparticles were successfully achieved by alternating UV and visible light irradiation to obtain morphology-controlled drug release in a switch mode. PMID:26343347

  14. Temperature-Controlled Clamping and Releasing Mechanism

    NASA Technical Reports Server (NTRS)

    Rosing, David; Ford, Virginia

    2005-01-01

    A report describes the development of a mechanism that automatically clamps upon warming and releases upon cooling between temperature limits of approx. =180 K and approx. =293 K. The mechanism satisfied a need specific to a program that involved repeated excursions of a spectrometer between a room-temperature atmospheric environment and a cryogenic vacuum testing environment. The mechanism was also to be utilized in the intended application of the spectrometer, in which the spectrometer would be clamped for protection during launch of a spacecraft and released in the cold of outer space to allow it to assume its nominal configuration for scientific observations. The mechanism is passive in the sense that its operation does not depend on a control system and does not require any power other than that incidental to heating and cooling. The clamping and releasing action is effected by bolt-preloaded stacks of shape-memory-alloy (SMA) cylinders. In designing this mechanism, as in designing other, similar SMA mechanisms, it was necessary to account for the complex interplay among thermal expansion, elastic and inelastic deformation under load, and SMA thermomechanical properties.

  15. Cattle fly control using controlled-release insecticides.

    PubMed

    Tarry, D W

    1985-10-01

    Field trials were carried out from 1980 to 1984 on the use of a controlled-release pesticidal fly control technique on farms in Sussex, England, with a recurrent infectious keratoconjunctivitis problem related to fly attack. Pesticide impregnated p.v.c. ear-tags provided control of biting and disease-carrying fly species throughout the season. Over 90% control of flies, compared with untreated herds, was attained using 2 tags impregnated with cypermethrin, fenvalerate or flucythrinate, although control using a single tag was unsatisfactory. In all cases infectious keratoconjunctivitis was almost completely eliminated. PMID:4082447

  16. Pulmonary liposomal formulations encapsulated procaterol hydrochloride by a remote loading method achieve sustained release and extended pharmacological effects.

    PubMed

    Tahara, Kohei; Tomida, Hiromasa; Ito, Yousuke; Tachikawa, Suguru; Onodera, Risako; Tanaka, Hiroyuki; Tozuka, Yuichi; Takeuchi, Hirofumi

    2016-05-30

    Drug inhalation provides localized drug therapy for respiratory diseases. However, the therapeutic efficacy of inhaled drugs is limited by rapid clearance from the lungs. Small hydrophilic compounds have short half-lives to systemic absorption. We developed a liposomal formulation as a sustained-release strategy for pulmonary delivery of procaterol hydrochloride (PRO), a short-acting pulmonary β2-agonist for asthma treatment. After PRO-loaded liposomes were prepared using a pH gradient (remote loading) method, 100-nm liposomes improved residence times of PRO in the lungs. PRO encapsulation efficiency and release profiles were examined by screening several liposomal formulations of lipid, cholesterol, and inner phase. Although PRO loading was not achieved using the conventional hydration method, PRO encapsulation efficiency was >60% using the pH gradient method. PRO release from liposomes was sustained for several hours depending on liposomal composition. The liposomal formulation effects on the PRO behavior in rat lungs were evaluated following pulmonary administration in vivo. Sustained PRO release was achieved using simplified egg phosphatidylcholine (EPC)/cholesterol (8/1) liposome in vitro, and greater PRO remnants were observed in rat lungs following pulmonary administration. Extended pharmacological PRO effects were observed for 120min in a histamine-induced bronchoconstriction guinea pig model. We indicated the simplified EPC/cholesterol liposome potential as a controlled-release PRO carrier for pulmonary administration. PMID:27012982

  17. A rapid technique for prediction of nutrient release from controlled release fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient release from soluble granular fertilizers can be modified by polymer coating to extend the total duration nutrient release up to 3 to 9 months and rate of release to match the nutrient requirement of the plant during the growing period. Hence these products are termed as “Controlled Release...

  18. Metering Best Practices, A Guide to Achieving Utility Resource Efficiency, Release 2.0

    SciTech Connect

    Sullivan, Greg; Hunt, W. D.; Pugh, Ray; Sandusky, William F.; Koehler, Theresa M.; Boyd, Brian K.

    2011-08-31

    This release is an update and expansion of the information provided in Release 1.0 of the Metering Best Practice Guide that was issued in October 2007. This release, as was the previous release, was developed under the direction of the U.S. Department of Energy's Federal Energy Management Program (FEMP). The mission of FEMP is to facilitate the Federal Government's implementation of sound cost-effective energy management and investment practices to enhance the nation's energy security and environmental stewardship. Each of these activities is directly related to achieving requirements set forth in the Energy Policy Acts of 1992 and 2005, the Energy Independence and Security Act (EISA) of 2007, and the goals that have been established in Executive Orders 13423 and 13514 - and also those practices that are inherent in sound management of Federal financial and personnel resources.

  19. Diisocyanate mediated polyether modified gelatin drug carrier for controlled release

    PubMed Central

    Vijayakumar, Vediappan; Subramanian, Kaliappagounder

    2013-01-01

    Gelatin is an extensively studied biopolymer hydrogel drug carrier due to its biocompatibility, biodegradability and non-toxicity of its biodegraded products formed in vivo. But with the pristine gelatin it is difficult to achieve a controlled and desirable drug release characteristics due to its structural and thermal lability and high solubility in aqueous biofluids. Hence it is necessary to modify its solubility and structural stability in biofluids to achieve controlled release features with improved drug efficacy and broader carrier applications. In the present explorations an effort is made in this direction by cross linking gelatin to different extents using hitherto not studied isocyanate terminated poly(ether) as a macrocrosslinker prepared from poly(ethylene glycol) and isophorone diisocyanate in dimethyl sulfoxide. The crosslinked samples were analyzed for structure by Fourier transform-infrared spectroscopy, thermal behavior through thermogravimetric analysis and differential scanning calorimetry. The cross linked gelatins were biodegradable, insoluble and swellable in biofluids. They were evaluated as a carrier for in vitro drug delivery taking theophylline as a model drug used in asthma therapy. The crosslinking of gelatin decreased the drug release rate by 10–20% depending upon the extent of crosslinking. The modeled drug release characteristics revealed an anomalous transport mechanism. The release rates for ampicillin sodium, 5-fluorouracil and theophylline drugs in a typical crosslinked gelatin carrier were found to depend on the solubility and hydrophobicity of the drugs, and the pH of the fluid. The observed results indicated that this material can prove its mettle as a viable carrier matrix in drug delivery applications. PMID:24493973

  20. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    PubMed Central

    Yassine, Omar; Zaher, Amir; Li, Er Qiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T.; Khashab, Niveen M.; Kosel, Jurgen

    2016-01-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads. PMID:27335342

  1. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications.

    PubMed

    Yassine, Omar; Zaher, Amir; Li, Er Qiang; Alfadhel, Ahmed; Perez, Jose E; Kavaldzhiev, Mincho; Contreras, Maria F; Thoroddsen, Sigurdur T; Khashab, Niveen M; Kosel, Jurgen

    2016-01-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads. PMID:27335342

  2. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    NASA Astrophysics Data System (ADS)

    Yassine, Omar; Zaher, Amir; Li, Er Qiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T.; Khashab, Niveen M.; Kosel, Jurgen

    2016-06-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

  3. Controlled Release of Agrochemicals Intercalated into Montmorillonite Interlayer Space

    PubMed Central

    2014-01-01

    Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil. PMID:24696655

  4. Controlled Release for Local Delivery of Drugs: Barriers and Models

    PubMed Central

    Weiser, Jennifer R.; Saltzman, W. Mark

    2014-01-01

    Controlled release systems are an effective means for local drug delivery. In local drug delivery, the major goal is to supply therapeutic levels of a drug agent at a physical site in the body for a prolonged period. A second goal is to reduce systemic toxicities, by avoiding the delivery of agents to non-target tissues remote from the site. Understanding the dynamics of drug transport in the vicinity of a local drug delivery device is helpful in achieving both of these goals. Here, we provide an overview of controlled release systems for local delivery and we review mathematical models of drug transport in tissue, which describe the local penetration of drugs into tissue and illustrate the factors—such as diffusion, convection, and elimination—that control drug dispersion and its ultimate fate. This review highlights the important role of controlled release science in development of reliable methods for local delivery, as well as the barriers to accomplishing effective delivery in the brain, blood vessels, mucosal epithelia, and the skin. PMID:24801251

  5. 28 CFR 541.50 - Release from a control unit.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Release from a control unit. 541.50 Section 541.50 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Control Unit Programs § 541.50 Release from a control unit. (a) Only the Executive Panel may release...

  6. Molecular gels-based controlled release devices for pheromones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    2-Heptanone is a volatile solvent that is effective in controlling parasitic mites (Varroa) in honeybee. Controlled-release of 2-heptanone is needed to avoid overdosing, minimize chemical usage, and provide a sustained release over a several week period. Control-release devices comprised of a reserv...

  7. Estimates of Savings Achievable from Irrigation Controller

    SciTech Connect

    Williams, Alison; Fuchs, Heidi; Whitehead, Camilla Dunham

    2014-03-28

    This paper performs a literature review and meta-analysis of water savings from several types of advanced irrigation controllers: rain sensors (RS), weather-based irrigation controllers (WBIC), and soil moisture sensors (SMS).The purpose of this work is to derive average water savings per controller type, based to the extent possible on all available data. After a preliminary data scrubbing, we utilized a series of analytical filters to develop our best estimate of average savings. We applied filters to remove data that might bias the sample such as data self-reported by manufacturers, data resulting from studies focusing on high-water users, or data presented in a non-comparable format such as based on total household water use instead of outdoor water use. Because the resulting number of studies was too small to be statistically significant when broken down by controller type, this paper represents a survey and synthesis of available data rather than a definitive statement regarding whether the estimated water savings are representative.

  8. Software control of intelligent drug releases using stimuli-responsive release systems and IR data communication

    NASA Astrophysics Data System (ADS)

    Sakata, Shoei; Uchida, Kumao; Kaetsu, Isao; Kita, Yoshimi; Tsuji, Daisuke

    2007-04-01

    Intelligent drug delivery systems using UV polymerized hydrogels controlled by software were developed. The conditions of drug releases such as drug concentration, timing and amount of released drug could be controlled. It was also shown that the release threshold and the program design could be modified by IR data communication.

  9. Poly (lactic-co-glycolic acid) controlled release systems: experimental and modeling insights

    PubMed Central

    Hines, Daniel J.; Kaplan, David L.

    2013-01-01

    Poly-lactic-co-glycolic acid (PLGA) has been the most successful polymeric biomaterial for use in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in drug release device formulation. Mathematical modeling is a useful tool for identifying, characterizing, and predicting the mechanisms of controlled release. The advantages and limitations of poly (lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled release technology that utilize PLGA. Mathematical modeling applied towards controlled release rates from PLGA-based devices will also be discussed to provide a complete picture of state of the art understanding of the control achievable with this polymeric system, as well as the limitations. PMID:23614648

  10. Controlled release of vancomycin from biodegradable microcapsules.

    PubMed

    Ozalp, Y; Ozdemir, N; Kocagöz, S; Hasirci, V

    2001-01-01

    Poly D,L-lactic acid (PLA) and its copolymers with glycolide PLGA 90:10 and 70:30 were polymerized under various conditions to yield polymers in the molecular weight range 12000-40000 daltons, as determined by gel permeation chromatography. Vancomycin hydrochloride was the hydrophilic drug of choice for the treatment of methicillin resistant Staphyloccoccal infections. It was microencapsulated in the synthesized polymers using water-oil-water (w/o/w) double emulsion and solvent evaporation. The influence of microcapsule preparation medium on product properties was investigated. An increase in polymer-to-drug ratio from 1:1 to 3:1 caused an increase in the encapsulation efficiency (i.e. from 44-97% with PLGA). An increase in the emulsifier (PVA) molecular weight from 14-72 kD caused an increase in encapsulation efficiency and microcapsule size. The in vitro release of vancomycin from microcapsules in phosphate buffer saline (pH 7.4) was found to be dependent on molecular weight and copolymer type. The kinetic behaviour was controlled by both diffusion and degradation. Sterilization with 60Co (2.5 Mrad) also affected the degradation rate and release profiles. Degradation of microcapsules could be seen by scanning electron microscopy, by the increase in the release rate from PLA and by the decrease in the Tg values of microcapsules. In vitro bactericidal effects of the microcapsule formulations on S. aureus were determined with a special diffusion cell after the preparations had been sterilized, and were found to have bactericidal effects lasting for 4 days. PMID:11201344

  11. Controlled release of water-soluble herbicides

    SciTech Connect

    Riggle, B.D.

    1985-01-01

    Pine kraft lignin was used to control the release of metribuzin (4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one) and alachlor (2-chloro-2',6'-diethyl-N-methoxy-methyl acetanalide). Soil thin layer chromatography (TLC) analysis using /sup 14/C-metribuzin and /sup 14/C-alachlor demonstrated that NB-5203-58 series and PC940 series kraft lignins could retard the mobility of both herbicides after multiple soil TLC plate developments with water. Soil column chromatography analysis demonstrated that PC940C could retard the mobility of both herbicides after soil column water leaching by positioning the herbicides in the top portion of the soil column where the PC940C-herbicide mixture had been applied. There was a concentration effect where, as more PC940C was used, more /sup 14/C-labelled herbicide was retained in the top portion of the soil columns. Soil column chromatography and soil TLC plate analysis demonstrated that /sup 3/H-PC940C was immobile. Finally, PC940C significantly reduced metribuzin related phytotoxicity to field and greenhouse grown soybeans (Glycine max (L.) Merr.) which had been treated with PC940C rates of 0.77 and 1.15 L/ha and metribuzin rates of 0.42 and 0.84 kg/ha. The results for /sup 14/C-metribuzin and /sup 14/C-alachlor as well as the reduction in metribuzin related phytotoxicity to soybeans suggests that PC940C can effectively control the release of metribuzin and alachlor.

  12. Stable Ultrathin-Shell Double Emulsions for Controlled Release.

    PubMed

    Zhao, Chun-Xia; Chen, Dong; Hui, Yue; Weitz, David A; Middelberg, Anton P J

    2016-06-01

    Double emulsions are normally considered as metastable systems and this limit in stability restricts their applications. To enhance their stability, the outer shell can be converted into a mechanically strong layer, for example, a polymeric layer, thus allowing improved performance. This conversion can be problematic for food and drug applications, as a toxic solvent is needed to dissolve the polymer in the middle phase and a high temperature is required to remove the solvent. This process can also be highly complex, for example, involving UV initiation of polymeric monomer crosslinking. In this study, we report the formation of biocompatible, water-in-oil-in-water (W/O/W) double emulsions with an ultrathin layer of fish oil. We demonstrate their application for the encapsulation and controlled release of small hydrophilic molecules. Without a trigger, the double emulsions remained stable for months, and the release of small molecules was extremely slow. In contrast, rapid release was achieved by osmolarity shock, leading to complete release within 2 h. This work demonstrates the significant potential of double emulsions, and provides new insights into their stability and practical applications. PMID:26934572

  13. A Rapid Test for Prediction of Nutrient Release from Controlled Release Fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient release from soluble granular fertilizers can be modified by polymer coating. The coating technology can be fine-tuned to change the duration (3 to 9 months) and rate of nutrient release, hence these products are termed as controlled release fertilizers (CRF). There is a need to develop a r...

  14. Residential Mobility, Inhibitory Control, and Academic Achievement in Preschool

    ERIC Educational Resources Information Center

    Schmitt, Sara A.; Finders, Jennifer K.; McClelland, Megan M.

    2015-01-01

    Research Findings: The present study investigated the direct effects of residential mobility on children's inhibitory control and academic achievement during the preschool year. It also explored fall inhibitory control and academic skills as mediators linking residential mobility and spring achievement. Participants included 359 preschool…

  15. Residential Mobility, Inhibitory Control, and Academic Achievement in Preschool

    ERIC Educational Resources Information Center

    Schmitt, Sara A.; Finders, Jennifer K.; McClelland, Megan M.

    2015-01-01

    The present study investigated the direct effects of residential mobility on children's inhibitory control and academic achievement during the preschool year. It also explored fall inhibitory control and academic skills as mediators linking residential mobility and spring achievement. Participants included 359 preschool children (49% female)…

  16. Longitudinal Effects of Perceived Control on Academic Achievement

    ERIC Educational Resources Information Center

    You, Sukkyung; Hong, Sehee; Ho, Hsiu-Zu

    2011-01-01

    It is well established that perceived control plays an important role in student academic achievement, but little is known about its longitudinal stability, ethnic variation, and developmental effects on subsequent achievement during adolescence. Findings from this study indicated (a) perceived control remains stable during adolescence for each of…

  17. Multifunctional Magnetoliposomes for Sequential Controlled Release.

    PubMed

    Salvatore, Annalisa; Montis, Costanza; Berti, Debora; Baglioni, Piero

    2016-08-23

    The simultaneous or sequential delivery of multiple therapeutic active principles to a specific target is one of the main challenges of nanomedicine. This goal requires the construction of complex devices often extremely time and cost consuming. Supramolecular self-assemblies, with building blocks of different nature, each providing a specific function to the final construct, can combine a facile synthetic route with a high tunability and structural control. In this study we provide the proof-of-principle of a drug delivery system, DDS, constituted of (i) liposomes, providing a fully biocompatible lipid scaffold suitable to host both hydrophobic and hydrophilic drugs; (ii) a double-stranded DNA conjugated with a cholesteryl unit that spontaneously inserts into the lipid membrane; and (iii) hydrophobic and hydrophilic superparamagnetic iron oxide nanoparticles (SPIONs) embedded inside the lipid membrane of liposomes or connected to the DNA, respectively. Upon application of an alternating magnetic field, the SPIONs can trigger, through thermal activation, the release of a DNA strand or of the liposomal payload, depending on the frequency and the application time of the field, as proved by both steady-state and time-resolved fluorescence studies. This feature is due to the different localization of the two kinds of SPIONS within the construct and demonstrates the feasibility of a multifunctional DDS, built up from self-assembly of biocompatible building blocks. PMID:27504891

  18. 28 CFR 541.50 - Release from a control unit.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Release from a control unit. 541.50 Section 541.50 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Control Unit Programs § 541.50 Release from a control...

  19. Dual-cargo selectively controlled release based on a pH-responsive mesoporous silica system.

    PubMed

    Gui, Wanyuan; Wang, Wenqian; Jiao, Xiangyu; Chen, Lifeng; Wen, Yongqiang; Zhang, Xueji

    2015-02-23

    A pH-controlled delivery system based on mesoporous silica nanoparticles (MSNs) was constructed for dual-cargo selective release. To achieve a better controlled-release effect, a modified sol-gel method was employed to obtain MSNs with tunable particle and pore sizes. The systems selectively released different kinds of cargo when stimulated by different pH values. At the lower pH value (pH 2.0) only one kind of cargo was released from the MSNs, whereas at a higher pH value (pH 7.0) only the other kind of cargo was released from the MSNs. The multi-cargo delivery system has brought the concept of selective release to new advances in the field of functional nanodevices and allows more accurate and controllable delivery of specific cargoes, which is expected to have promising applications in nanomedicine. PMID:25492672

  20. Hurdle Effect of Antimicrobial Activity Achieved by Time Differential Releasing of Nisin and Chitosan Hydrolysates from Bacterial Cellulose.

    PubMed

    Hsiao, Hui-Ling; Lin, Shih-Bin; Chen, Li-Chen; Chen, Hui-Huang

    2016-05-01

    We investigated the combined antimicrobial effect of nisin and chitosan hydrolysates (CHs) by regulating the antimicrobial reaction order of substances due to differential releasing rate from hydroxypropylmethylcellulose-modified bacterial cellulose (HBC). The minimum inhibitory concentration of nisin against Staphylococcus aureus and that of CHs against Escherichia coli were 6 IU and 200 μg/mL, respectively. Hurdle and additive effects in antimicrobial tests were observed when nisin was used 6 h before CH treatment against S. aureus; similar effects were observed when CH was used before nisin treatment against E. coli. Simultaneously combined treatment of nisin and CHs exhibited the low antimicrobial effect. HBC was then selected as the carrier for the controlled release of nisin and CHs. A 90% inhibition in the growth of S. aureus and E. coli was achieved when 30 IU-nisin-containing HBC and 62.5 μg/mL-CH-containing HBC were used simultaneously. The controlled release of nisin and CHs by using HBC minimized the interaction between nisin and CHs as well as increased the number of microbial targets. PMID:27074534

  1. Metal-organic framework tethering PNIPAM for ON-OFF controlled release in solution.

    PubMed

    Nagata, Shunjiro; Kokado, Kenta; Sada, Kazuki

    2015-05-21

    A smart metal-organic framework (MOF) exhibiting controlled release was achieved by modification with a thermoresponsive polymer (PNIPAM) via a surface-selective post-synthetic modification technique. Simple temperature variation readily switches "open" (lower temperature) and "closed" (higher temperature) states of the polymer-modified MOF through conformational change of PNIPAM grafted onto the MOF, resulting in controlled release of the included guest molecules such as resorufin, caffeine, and procainamide. PMID:25896867

  2. Laser-activated nano-biomaterials for tissue repair and controlled drug release

    SciTech Connect

    Matteini, P; Ratto, F; Rossi, F; Pini, R

    2014-07-31

    We present recent achievements of minimally invasive welding of biological tissue and controlled drug release based on laser-activated nano-biomaterials. In particular, we consider new advancements in the biomedical application of near-IR absorbing gold nano-chromophores as an original solution for the photothermal repair of surgical incisions and as nanotriggers of controlled drug release from hybrid biopolymer scaffolds. (laser biophotonics)

  3. Electrically credible polymer gel for controlled release of drugs

    NASA Astrophysics Data System (ADS)

    Kwon, Ick Chan; Bae, You Han; Kim, Sung Wan

    1991-11-01

    NEW controlled drug-delivery systems are being explored to overcome the disadvantages of conventional dosage forms1. For example, stimulated drug-delivery has been used to overcome the tolerance problems that occur with a constant delivery rate, to mimic the physiological pattern of hormonal concentration and to supply drugs on demand1,2. Stimuli-sensitive polymers, which are potentially useful for pulsed drug delivery, experience changes in either their structure or their chemical properties in response to changes in environmental conditions2. Environmental stimuli include temperature3,4, pH5,6, light (ultraviolet7 or visible8), electric field9-12 or certain chemicals13. Volume changes of stimuli-sensitive gel networks are particularly responsive to external stimuli, but swelling is slow to occur14,15. As well as being useful in the controlled release of drugs, such systems also provide insight into intermolecular interactions16. Here we report on a novel polymeric system, which rapidly changes from a solid state to solution in response to small electric currents, by disintegration of the solid polymer complex into two water-soluble polymers. We show that the modulated release of insulin, and by extension other macromolecules, can be achieved with this polymeric system.

  4. Environmental Release Prevention and Control Plan

    SciTech Connect

    Mamatey, A.; Arnett, M.

    1997-10-01

    During the history of SRS, continual improvements in facilities, process, and operations, and changes in the site`s mission have reduced the amount of radioactive liquid releases. In the early years of SRS (1958 to 1965), the amount of tritium discharged to the Savannah River averaged approximately 61,000 curies a year. During the mid-1980`s (1983 to 1988), liquid releases of tritium averaged 27,000 curies a year. By 1996, liquid releases of tritium are projected to be just 3000 curies for the year. This large projected decrease is the result of the planned shut-down of all reactors and the anticipated significant decline in the amount of tritium migrating from the site seepage basins and the Solid Waste Disposal Facility.

  5. [Nutrient release characteristics and use efficiency of slow- and controlled release fertilizers].

    PubMed

    Duan, Lu-Lu; Zhang, Min; Liu, Gang; Shang, Zhao-Cong; Yang, Yi

    2009-05-01

    Water extraction method and soil incubation method were used to study the nutrient release characteristics of four slow- and controlled release fertilizers (CRF1, CRF2, SCU, and IBDU), and pot experiment was conducted to assess the effects of the release characteristics on the nutrient requirements of canola (Brassica napus L.). The nutrient release curves of test fertilizers in water were S pattern for CRF1 and CRF2, burst pattern for SCU, and reverse L pattern for IBDU. The nutrient release characteristics of the four fertilizers in water and in soil all fitted binomial equations, suggesting that there existed some similarities in the nutrient release in the two media. The nutrient uptake and biomass of canola plants treated with CRF1 and CRF2 were significantly higher than those treated with SCU and IBDU, and CRF2 had the greatest effect. The nutrient release curves of CRF1 and CRF2 accorded more closely with the nutrient requirements of canola. PMID:19803169

  6. Controlled iodine release from polyurethane sponges for water decontamination.

    PubMed

    Aviv, Oren; Laout, Natalia; Ratner, Stanislav; Harik, Oshrat; Kunduru, Konda Reddy; Domb, Abraham J

    2013-12-28

    Iodinated polyurethane (IPU) sponges were prepared by immersing sponges in aqueous/organic solutions of iodine or exposing sponges to iodine vapors. Iodine was readily adsorbed into the polymers up to 100% (w/w). The adsorption of iodine on the surface was characterized by XPS and SEM analyses. The iodine loaded IPU sponges were coated with ethylene vinyl acetate (EVA), in order to release iodine in a controlled rate for water decontamination combined with active carbon cartridge, which adsorbs the iodine residues after the microbial inactivation. The EVA coated IPU were incorporated in a water purifier and tested for iodine release to water and for microbial inactivation efficiency according to WQA certification program against P231/EPA for 250l, using 25l a day with flow rate of 6-8min/1l. The antimicrobial activity was also studied against Escherichia coli and MS2 phage. Bacterial results exceeded the minimal requirement for bacterial removal of 6log reduction throughout the entire lifespan. At any testing point, no bacteria was detected in the outlet achieving more than 7.1 to more than 8log reduction as calculated upon the inlet concentration. Virus surrogate, MS2, reduction results varied from 4.11log reduction under tap water, and 5.11log reduction under basic water (pH9) to 1.32 for acidic water (pH5). Controlled and stable iodine release was observed with the EVA coated IPU sponges and was effective in deactivating the bacteria and virus present in the contaminated water and thus, these iodinated PU systems could be used in water purification to provide safe drinking water. These sponges may find applications as disinfectants in medicine. PMID:24096017

  7. Overview study of LNG release prevention and control systems

    SciTech Connect

    Pelto, P.J.; Baker, E.G.; Holter, G.M.; Powers, T.B.

    1982-03-01

    The liquefied natural gas (LNG) industry employs a variety of release prevention and control techniques to reduce the likelihood and the consequences of accidental LNG releases. A study of the effectiveness of these release prevention and control systems is being performed. Reference descriptions for the basic types of LNG facilities were developed. Then an overview study was performed to identify areas that merit subsequent and more detailed analyses. The specific objectives were to characterize the LNG facilities of interest and their release prevention and control systems, identify possible weak links and research needs, and provide an analytical framework for subsequent detailed analyses. The LNG facilities analyzed include a reference export terminal, marine vessel, import terminal, peakshaving facility, truck tanker, and satellite facility. A reference description for these facilities, a preliminary hazards analysis (PHA), and a list of representative release scenarios are included. The reference facility descriptions outline basic process flows, plant layouts, and safety features. The PHA identifies the important release prevention operations. Representative release scenarios provide a format for discussing potential initiating events, effects of the release prevention and control systems, information needs, and potential design changes. These scenarios range from relatively frequent but low consequence releases to unlikely but large releases and are the principal basis for the next stage of analysis.

  8. Layered superhydrophobic meshes for controlled drug release.

    PubMed

    Falde, Eric J; Freedman, Jonathan D; Herrera, Victoria L M; Yohe, Stefan T; Colson, Yolonda L; Grinstaff, Mark W

    2015-09-28

    Layered superhydrophobic electrospun meshes composed of poly(ε-caprolactone) (PCL) and poly(glycerol monostearate-co-ε-caprolactone) (PGC-C18) are described as a local source of chemotherapeutic delivery. Specifically, the chemotherapeutic agent SN-38 is incorporated into a central 'core' layer, between two 'shield' layers of mesh without drug. This mesh is resistant to wetting of the surface and throughout the bulk due to the pronounced hydrophobicity imparted by the high roughness of a hydrophobic polymer, PGC-C18. In serum solution, these meshes exhibit slow initial drug release over 10days corresponding to media infiltrating the shield layer, followed by steady release over >30days, as the drug-loaded core layer is wetted. This sequence of events is supported by X-ray computed tomography imaging of a contrast agent solution infiltrating the mesh. In vitro cytotoxicity data collected with Lewis Lung Carcinoma (LLC) cells are consistent with this release profile, remaining cytotoxic for over 20days, longer than the unlayered version. Finally, after subcutaneous implantation in rats, histology of meshes with and without drug demonstrated good integration and lack of adverse reaction over 28days. The drug release rates, robust superhydrophobicity, in vitro cytotoxicity of SN-38 loaded meshes, and compatibility provide key design parameters for the development of an implantable chemotherapeutic-loaded device for the prevention of local lung cancer recurrence following surgical resection. PMID:26160309

  9. Interrelationships of Study Habits and Attitudes, Locus of Control, Motivation Achievement Tendencies and Academic Achievement.

    ERIC Educational Resources Information Center

    Gadzella, Bernadette M.; And Others

    The study investigated (a) relationships between measures on study habits and attitudes, locus of control, achieving tendency, and semester grade-point averages (SGPA), (b) differences between the sexes on the above mentioned variables, and (c) best predictor of SGPA. The subjects were 39 males and 81 females. There were a number of significant…

  10. The Impact of Locus of Control on Language Achievement

    ERIC Educational Resources Information Center

    Nodoushan, Mohammad Ali Salmani

    2012-01-01

    This study hypothesized that students' loci of control affected their language achievement. 198 (N = 198) EFL students took the Rotter's (1966) locus of control test and were classified as locus-internal (ni = 78), and locus-external (ne = 120). They then took their ordinary courses and at the end of the semester, they were given their exams.…

  11. NUTRIENT RELEASE CHARACTERISTICS FROM FOUR TYPES OF CONTROLLED-RELEASE FERTILIZERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Release patterns of ammonium, nitrate, phosphorous, potassium, calcium, magnesium, iron, manganese, and zinc were measured during an eleven month period for four types of Controlled Release Fertilizers (CRF): Apex 17-5-11, Multicote 17-5-11, Nutricote 18-6-8, and Osmocote 24-4-9. Rate of fertilizer...

  12. Nitrogen Release in Different Soils Amended with Controlled-Release Fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) release from two controlled-release N fertilizers (CRNFs) (Arborite® and ESN®) and two traditional N fertilizers (urea [(NH2)2CO)] and ammonium urea nitrate (UAN) [(NH2)2CO, NH4NO3]) in three soil types of North Carolina was measured throughout a 12 week laboratory incubation. Treatment...

  13. Exploitation of novel gum Prunus cerasoides as mucoadhesive beads for a controlled-release drug delivery.

    PubMed

    Seelan, T Veenus; Kumari, Henry Linda Jeeva; Kishore, Narra; Selvamani, Palanisamy; Lalhlenmawia, H; Thanzami, K; Pachuau, Lalduhsanga; Ruckmani, Kandasamy

    2016-04-01

    The present study deals with the formulation of pH-sensitive mucoadhesive beads using natural gum isolated from Prunus cerasoides (PC) in combination with sodium alginate (SA) for the controlled release of diclofenac sodium (DS). PC and SA composite (PC-SA), DS loaded SA (DS-SA) and DS loaded PC-SA (DS-PC-SA) beads were prepared by ionotropic gelation method. The absence of interaction between DS and PC-SA was shown by FTIR, DSC and TGA analyses. The optimized DS-PC-SA formulation exhibited mucoadhesive property and the controlled release of DS was achieved 68% in 12h. The in vitro release kinetics follows zero order with anomalous diffusion mechanism. Therefore, the formulated mucoadhesive beads with the novel gum are preferable for the controlled release of DS by prolonging the residence time of the drug in the gastrointestinal tract, overcoming the problems associated with the immediate release dosage forms of DS. PMID:26772921

  14. Electrospinning nanofibers for controlled drug release

    NASA Astrophysics Data System (ADS)

    Banik, Indrani

    Electrospinning is the most widely studied technique for the synthesis of nanofibers. Electrospinning is considered as one of the technologies that can produce nanosized drugs incorporated in polymeric nanofibers. In vitro and in vivo studies have demonstrated that the release rates of drugs from these nanofiber formulations are enhanced compared to those from original drug substance. This technology has the potential for enhancing the oral delivery of poorly soluble drugs. The electrospun mats were made using Polycaprolactone/PCL, Poly(DL-lactide)/PDL 05 and Poly(DL-lactide-co-glycolide)/PLGA. The drugs incorporated in the electrospun fibers were 5-Fluorouracil and Rapamycin. The evidence of the drugs being embedded in the polymers was obtained by scanning electron microscopy (SEM), Raman and infrared spectroscopy. The release of 5-Fluorouracil and Rapamycin were followed by UV-VIS spectroscopy.

  15. Growth-Factor Nanocapsules That Enable Tunable Controlled Release for Bone Regeneration.

    PubMed

    Tian, Haijun; Du, Juanjuan; Wen, Jing; Liu, Yang; Montgomery, Scott R; Scott, Trevor P; Aghdasi, Bayan; Xiong, Chengjie; Suzuki, Akinobu; Hayashi, Tetsuo; Ruangchainikom, Monchai; Phan, Kevin; Weintraub, Gil; Raed, Alobaidaan; Murray, Samuel S; Daubs, Michael D; Yang, Xianjin; Yuan, Xu-Bo; Wang, Jeffrey C; Lu, Yunfeng

    2016-08-23

    Growth factors are of great potential in regenerative medicine. However, their clinical applications are largely limited by the short in vivo half-lives and the narrow therapeutic window. Thus, a robust controlled release system remains an unmet medical need for growth-factor-based therapies. In this research, a nanoscale controlled release system (degradable protein nanocapsule) is established via in situ polymerization on growth factor. The release rate can be finely tuned by engineering the surface polymer composition. Improved therapeutic outcomes can be achieved with growth factor nanocapsules, as illustrated in spinal cord fusion mediated by bone morphogenetic protein-2 nanocapsules. PMID:27227573

  16. Controlled Release Pulmonary Administration of Curcumin Using Swellable Biocompatible Microparticles

    PubMed Central

    El-Sherbiny, Ibrahim M.; Smyth, Hugh D. C.

    2012-01-01

    This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nano and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of (221-243 nm) and (3.1-3.9 μm), respectively. The developed carriers attained high swelling within a few minutes, showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in-vitro TNF-α assays were performed for the investigated particles. These assays revealed promising bio-interactions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery. PMID:22136259

  17. Controlled release pulmonary administration of curcumin using swellable biocompatible microparticles.

    PubMed

    El-Sherbiny, Ibrahim M; Smyth, Hugh D C

    2012-02-01

    This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nanoparticles and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of 221-243 nm and 3.1-3.9 μm, respectively. The developed carriers attained high swelling within a few minutes and showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor, and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in vitro TNF-α assays were performed for the investigated particles. These assays revealed promising biointeractions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery. PMID:22136259

  18. Release and control of hydrogen sulfide during sludge thermal drying

    SciTech Connect

    Weng, Huanxin; Dai, Zhixin; Ji, Zhongqiang; Gao, Caixia; Liu, Chongxuan

    2015-04-15

    The release of hydrogen sulfide (H2S) during sludge drying is a major environmental problem because of its toxicity to human health. A series of experiments were performed to investigate the mechanisms and factors controlling the H2S release. Results of this study show that: 1) the biomass and activity of sulfate-reducing bacteria (SRB) in sludge were the major factors controlling the amount of H2S release, 2) the sludge drying temperature had an important effect on both the extent and the timing of H2S release from the sludge, and 3) decreasing sludge pH increased the H2S release. Based on the findings from this study, a new system that integrates sludge drying and H2S gas treatment was developed to reduce the amount of H2S released from sludge treatments.

  19. Controlled release of fragrant molecules with visible light.

    PubMed

    Wang, Zhuozhi; Johns, Valentine K; Liao, Yi

    2014-11-01

    Controlled release of odorous molecules is the key to digital scent technology which will add another dimension to electronics. Photorelease is a cold mechanism that promises better temporal and spatial control than thermal release. Herein we report a novel material composed of an acid-sensitive polymer carrying a fragrant aldehyde and a reversible metastable-state photoacid. It releases the fragrant molecule under visible light, and stops releasing it after the light is turned off. A metastable-state photoacid with a fast reverse-reaction rate was developed to quickly stop the release after irradiation. Both the carrier polymer and the photoacid can be reused after all the fragrant molecules have been released. The material combines the advantages of visible-light activity, fast on/off rate, easy preparation, and recyclability, and thus is promising for digital scent technology. PMID:25284277

  20. Purpose plus: supporting youth purpose, control, and academic achievement.

    PubMed

    Pizzolato, Jane Elizabeth; Brown, Elizabeth Levine; Kanny, Mary Allison

    2011-01-01

    Research in the past decade suggests that a persistent achievement gap between students from low-income minority backgrounds and higher-income white backgrounds may be rooted in theories of student motivation and youth purpose. Yet limited research exists regarding the role of purpose on positive youth development as it pertains to academic achievement. Using a sample of 209 high school students, this study examines the effectiveness of an intervention designed to promote purpose development and internal control over academic success in high school students from a low-socioeconomic-status community. Findings reveal that a short-term intervention was effective in significantly increasing internal control over academic success and purpose in life for students participating in the intervention group. In addition, analysis of academic achievement for students who experienced positive gains in internal control and purpose demonstrates significant gains in academic achievement as measured by grade point average. Implications are made for further study of internal control and life purpose as a means of academic intervention in the effort to address the achievement gap. PMID:22275280

  1. Controlled release of the herbicide simazine from computationally designed molecularly imprinted polymers.

    PubMed

    Piletska, Elena V; Turner, Nicholas W; Turner, Anthony P F; Piletsky, Sergey A

    2005-11-01

    The present study describes the development of materials suitable for environmental control of algae. Molecularly imprinted polymers (MIPs) were used as simazine carriers able to provide the controlled release of simazine into water. Three polymers were designed using computational modelling. The selection of methacrylic acid (MA) and hydroxyethyl methacrylate (HEM) as functional monomers was based on results obtained using the Leapfrog algorithm. A cross-linked polymer made without functional monomers was also prepared and tested as a control. The release of simazine from all three polymers was studied. It was shown that the presence of functional monomers is important for polymer affinity and for controlled release of herbicide. The speed of release of herbicide correlated with the calculated binding characteristics. The high-affinity MA-based polymer released approximately 2% and the low-affinity HEM-based polymer released approximately 27% of the template over 25 days. The kinetics of simazine release from HEM-based polymer show that total saturation of an aqueous environment could be achieved over a period of 3 weeks and this corresponds to the maximal simazine solubility in water. The possible use of these types of polymers in the field of controlled release is discussed. PMID:16111783

  2. Preparation, characterization and optimization of glipizide controlled release nanoparticles.

    PubMed

    Emami, J; Boushehri, M S Shetab; Varshosaz, J

    2014-01-01

    The purpose of the present study was to develop glipizide controlled release nanoparticles using alginate and chitosan thorough ionotropic controlled gelation method. Glipizide is a frequently prescribed second generation sulfonylurea which lowers the blood glucose in type-two diabetics. Quick absorption of the drug from the gastrointestinal tract along with short half- life of elimination makes it a good candidate for controlled release formulations. Alginate-chitosan nanoparticles (ACNP) are convenient controlled delivery systems for glipizide, due to both the release limiting properties of the system, and the bioadhesive nature of the polymers. In the present study, glipizide loaded alginate-chitosan nanoparticles (GlACNP) were prepared, and the particle characteristics including particle size (PS), zeta potential (ZP), entrapment efficiency (EE%), loading percent (LP), and mean release time (MRT), as well as the morphology of the nanoparticles, the drug-excipient compatibility, and the release kinetics along with the drug diffusion mechanism were evaluated. The results suggested that ionotropic controlled gelation method offers the possibility of preparing the nanoparticles in mild conditions in an aqueous environment, and can lead to the preparation of particles with favorable size, controlled release characteristics, and high entrapment efficiency, serving as a convenient delivery system for glipizide. The particle and release characteristics can be efficiently optimized using the Box-Behnken design. Based on the findings of the present study, it is expected that this novel formulation be a superior therapeutic alternative to the currently available glipizide delivery systems. PMID:25657802

  3. Preparation, characterization and optimization of glipizide controlled release nanoparticles

    PubMed Central

    Emami, J.; Boushehri, M.S. Shetab; Varshosaz, J.

    2014-01-01

    The purpose of the present study was to develop glipizide controlled release nanoparticles using alginate and chitosan thorough ionotropic controlled gelation method. Glipizide is a frequently prescribed second generation sulfonylurea which lowers the blood glucose in type-two diabetics. Quick absorption of the drug from the gastrointestinal tract along with short half- life of elimination makes it a good candidate for controlled release formulations. Alginate-chitosan nanoparticles (ACNP) are convenient controlled delivery systems for glipizide, due to both the release limiting properties of the system, and the bioadhesive nature of the polymers. In the present study, glipizide loaded alginate-chitosan nanoparticles (GlACNP) were prepared, and the particle characteristics including particle size (PS), zeta potential (ZP), entrapment efficiency (EE%), loading percent (LP), and mean release time (MRT), as well as the morphology of the nanoparticles, the drug-excipient compatibility, and the release kinetics along with the drug diffusion mechanism were evaluated. The results suggested that ionotropic controlled gelation method offers the possibility of preparing the nanoparticles in mild conditions in an aqueous environment, and can lead to the preparation of particles with favorable size, controlled release characteristics, and high entrapment efficiency, serving as a convenient delivery system for glipizide. The particle and release characteristics can be efficiently optimized using the Box-Behnken design. Based on the findings of the present study, it is expected that this novel formulation be a superior therapeutic alternative to the currently available glipizide delivery systems. PMID:25657802

  4. A Review: Controlled release systems for agricultural and food applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlled release systems are widely used in numerous applications. Polymers from natural resources, such as pectin, starch, zein and poly(lactic acid) have been used to construct carriers of bioactive substances and deliver them in a designed manner. The retention and release of volatile fragrance...

  5. Best Practices for Controlling Lead and Copper Release

    EPA Science Inventory

    Presentation draft, covering summary of current state-of-the-art knowledge for the best treatment strategies for minimizing lead release and controlling copper release. The presentation is intended to aid with compliance with the Lead and Copper Rule, but also provide a guide to...

  6. Controlled antibody release from gelatin for on-chip sample preparation.

    PubMed

    Zhang, Xichen; Wasserberg, Dorothee; Breukers, Christian; Terstappen, Leon W M M; Beck, Markus

    2016-05-10

    A practical way to realize on-chip sample preparation for point-of-care diagnostics is to store the required reagents on a microfluidic device and release them in a controlled manner upon contact with the sample. For the development of such diagnostic devices, a fundamental understanding of the release kinetics of reagents from suitable materials in microfluidic chips is therefore essential. Here, we study the release kinetics of fluorophore-conjugated antibodies from (sub-) μm thick gelatin layers and several ways to control the release time. The observed antibody release is well-described by a diffusion model. Release times ranging from ∼20 s to ∼650 s were determined for layers with thicknesses (in the dry state) between 0.25 μm and 1.5 μm, corresponding to a diffusivity of 0.65 μm(2) s(-1) (in the swollen state) for our standard layer preparation conditions. By modifying the preparation conditions, we can influence the properties of gelatin to realize faster or slower release. Faster drying at increased temperatures leads to shorter release times, whereas slower drying at increased humidity yields slower release. As expected in a diffusive process, the release time increases with the size of the antibody. Moreover, the ionic strength of the release medium has a significant impact on the release kinetics. Applying these findings to cell counting chambers with on-chip sample preparation, we can tune the release to control the antibody distribution after inflow of blood in order to achieve homogeneous cell staining. PMID:27077142

  7. Children's Effortful Control and Academic Achievement: Mediation through Social Functioning

    ERIC Educational Resources Information Center

    Valiente, Carlos; Eisenberg, Nancy; Haugen, Rg; Spinrad, Tracy L.; Hofer, Claire; Liew, Jeffrey; Kupfer, Anne

    2011-01-01

    Research Findings: The purpose of this study was to test the premise that children's effortful control (EC) is prospectively related to their academic achievement and to specify mechanisms through which EC is related to academic success. We used data from 214 children (M age at Time 1 [T1] = 73 months) to test whether social functioning (e.g.,…

  8. Controlled Release of Imidacloprid from Poly Styrene-Diacetone - Nanoformulation

    NASA Astrophysics Data System (ADS)

    Qian, Kun; Guo, Yanzhen; He, Lin

    2012-01-01

    Imidacloprid is a neonicotinoids insecticide, which is important for the cash crops such as tomato, rape and so on. The conventional formulation does not only increase the loss of pesticide but also leads to environmental pollution. Controlled-release formulations of pesticide are highly desirable not only for attaining the most effective utilization of the pesticide, but also for reducing environmental pollution. Pesticide imidacloprid was incorporated in poly (styrene-diacetone crylamide)-based formulation to obtain controlled release properties, and the imidacloprid nanocontrolled release formulation was characterized by infrared (IR) and field emission scanning electron microscope (FESEM). Factors related to loading efficiency, swelling and release behaviors of the formulation were investigated. It showed that the loading efficiency could reach about 40% (w/w). The values for the diffusion exponent "n" were in the range of 0.31-0.58, which indicated that the release of imidacloprid was diffusion-controlled. The time taken for 50% of the active ingredient to be released into water, T50, was also calculated for the comparison of formulations in different conditions. The results showed that the formulation with higher temperature and more diacetone crylamide had lower value of T50, which means a quicker release of the active ingredient. This study highlighted some pieces of evidence that improved pesticide incorporation and slower release were linked to potential interactions between the pesticide and the polymer.

  9. Tunable pH-Sensitive Linker for Controlled Release.

    PubMed

    Choy, Cindy J; Geruntho, Jonathan J; Davis, Austen L; Berkman, Clifford E

    2016-03-16

    We have developed a novel pH-sensitive linker based on a phosphoramidate scaffold that can be tuned to release amine-containing drug molecules at various pH values. The pH-triggered phosphoramidate-based linkers are responsive to pH alone and do not require intracellular enzymatic action to initiate drug release. Key to the pH-triggered amine release from these linkers is a proximal acidic group (e.g., pyridinium or carboxylic acid) to promote the hydrolysis of the phosphoramidate P-N bond, presumably through an intramolecular general-acid type mechanism. Phosphoramidate hydrolysis is largely governed by the pKa of the leaving amine (e.g., primary, secondary, aniline). However, the proximity of the neighboring pyridine group attenuates the stability of the P-N bond to hydrolysis, thus allowing for control over the release of an amine from the phosphoramidate center. Based on the model scaffolds examined, phosphoramidate-based linkers could be selected for particular properties for controlled-release applications such as amine type, stability under physiological conditions, or release rates at various pH values such as intracellular endosomal conditions. The tunability of the phosphoramidate scaffold is expected to find broad applicability in various controlled drug-release applications such as antibody or small-molecule drug conjugates, drug-eluting stents, prodrug activation, as well as intracellular trafficking studies in which pH changes can trigger the release of turn-on dyes. PMID:26886721

  10. Mucoadhesive controlled release ciprofloxacin nanoparticles for pulmonary delivery

    NASA Astrophysics Data System (ADS)

    Mudumba, Sujata S.

    Controlled release of drugs to the lungs is an interesting and evolving field of research. The influence of physicochemical properties of nanoparticles on the controlled release of ciprofloxacin and in-vivo pharmacokinetics following pulmonary administration was evaluated. The physicochemical properties had an effect on encapsulation efficiency and surface charge, but no significant effect on particle size. The in-vitro release profiles of ciprofloxacin in phosphate buffered saline showed small differences over the range of physicochemical properties evaluated. The physicochemical properties of ciprofloxacin nanoparticles resulted in variable and unreliable nebulizer output using a vibrating mesh nebulizer whereas the impact on the aerosol properties of a jet nebulizer was negligible. Addition of mucoadhesive polymers in the nanoparticles had a three-fold increase in apparent half-life in rats by releasing ciprofloxacin over an extended release period on the surfaces of the lungs.

  11. PREVENTION REFERENCE MANUAL: CONTROL TECHNOLOGIES, VOLUME 2: POST-RELEASE MITIGATION MEASURES FOR CONTROLLING ACCIDENTAL RELEASES OF AIR TOXICS

    EPA Science Inventory

    The volume discusses prevention and protection measures for controlling accidental releases of air toxics. The probability of accidental releases depends on the extent to which deviations (in magnitude and duration) in the process can be tolerated before a loss of chemical contai...

  12. PREVENTION REFERENCE MANUAL: CONTROL TECHNOLOGIES, VOL. 2. POST-RELEASE MITIGATION MEASURES FOR CONTROLLING ACCIDENTAL RELEASES OF AIR TOXICS

    EPA Science Inventory

    The volume discusses prevention and protection measures for controlling accidental releases of air toxics. The probability of accidental releases depends on the extent to which deviations (in magnitude and duration) in the process can be tolerated before a loss of chemical contai...

  13. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    PubMed Central

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nano-silver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nano-silver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over four orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by pre-oxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and release inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through bacterial inhibition zone assay carried out on selected formulations of controlled release nano-silver. PMID:20968290

  14. A controlled biochemical release device with embedded nanofluidic channels

    NASA Astrophysics Data System (ADS)

    Yang, Haifeng; Hong, Wei; Dong, Liang

    2012-04-01

    A controlled release device is developed by embedding nanofluidic biomolecule reservoirs into a polymer network of a stimuli-responsive hydrogel. The reservoirs are made of liquid core-polymer shell nanofibers using co-electrospinning. The mechanism of controlled release is based on buckling instability of the polymer shell under combined axial and radial compression, caused by volume changes of hydrogel responding to a specific stimulus. The device decouples releasable biomolecules from a hydrogel polymer matrix, avoiding chemical interactions between biomolecules and hydrogel polymer chains, and thus, alleviating nontrivial chemical and biological engineering design of hydrogel formulations. Temperature-sensitive hydrogel is used as a model hydrogel.

  15. Release of Ammonium and Mercury from NOx Controlled Fly Ash

    SciTech Connect

    Schroeder, K.T.; Cardone, C.R.; Kim, A.G

    2007-07-01

    One of the goals of the Department of Energy is to increase the reuse of coal utilization byproducts (CUB) to 50% by 2010. This will require both developing new markets and maintaining traditional ones such as the use of fly ash in concrete. However, the addition of pollution control devices can introduce side-effects that affect the marketability of the CUB. Such can be the case when NOx control is achieved using selective catalytic or non-catalytic reduction (SCR or SNCR). Depending on site-specific details, the ammonia slip can cause elevated levels of NH3 in the fly ash. Disposal of ammoniated fly ash can present environmental concerns related to the amount of ammonia that might be released, the amount of water that might become contaminated, and the extent to which metals might be mobilized by the presence of the ammonia. Ammonia retained in fly ash appears to be present as either an ammonium salt or as a chemisorbed species. Mercury in the leachates correlated to neither the amount of leachable ammonium nor to the total amount of Hg in the ash. The strongest correlation was between the decreases in the amount of Hg leached with increased LOI.

  16. The purposes, achievements, and priorities of arms control

    SciTech Connect

    Brown, P.S.

    1987-09-01

    Arms control purposes include strengthening the framework of deterrence and reducing the threat of the use of nuclear weapons, reducing the dangers of attack and accidental nuclear war, and allowing more resources for the civilian economy. The paper briefly describes achievements in arms control since World War II. These include the Limited Test Ban Treaty (LTBT), Nonproliferation Treaty (NPT), Anti-Ballistic Missile Treaty (ABMT)-SALT I, SALT II, Threshold Test Ban Treaty (TTBT), Peaceful Nuclear Explosions Treaty (PNET), and Nuclear-Free Zones treaties. The author also discusses his views on what the priorities of arms control activities should be. (ACR)

  17. Single wall carbon nanohorn as a drug carrier for controlled release

    NASA Astrophysics Data System (ADS)

    Xu, Jianxun; Yudasaka, Masako; Kouraba, Sachio; Sekido, Mitsuru; Yamamoto, Yuhei; Iijima, Sumio

    2008-08-01

    A single wall carbon nanohorn (SWNH) is a new kind of single-graphene tubules with a diameter of 2-5 nm and a length 40-50 nm. In this work, we used oxidized SWNH (SWNHox) to incorporate vancomycin hydrochloride (VCM) for its controlled release by taking advantage of the interactions between VCM and SWNHox. Phospholipid-poly(ethylene glycol) was used to modify the hydrophobic surface of SWNHox to improve its dispersion in aqueous systems. In the release study using this complex, a stable release of VCM was achieved for an extended period.

  18. Supramolecular Controlled Cargo Release via Near Infrared Tunable Cucurbit[7]uril-Gold Nanostars

    PubMed Central

    Han, Yanwei; Yang, Xiran; Liu, Yingzhu; Ai, Qiushuang; Liu, Simin; Sun, Chunyan; Liang, Feng

    2016-01-01

    The near infrared (NIR) absorption and average particle size of gold nanostars (GNSs) can be precisely controlled by varying the molar ratios of cucurbit[7]urils (CB[7]) and GNSs in aqueous solution. GNSs modified with CB[7] achieved high cargo loading with thermally activated release upon the NIR laser irradiation. PMID:26917240

  19. Controllable Multicompartmental Capsules with Distinct Cores and Shells for Synergistic Release.

    PubMed

    He, Fan; Wang, Wei; He, Xiao-Heng; Yang, Xiu-Lan; Li, Ming; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2016-04-01

    A facile and flexible approach is developed for controllable fabrication of novel multiple-compartmental calcium alginate capsules from all-aqueous droplet templates with combined coextrusion minifluidic devices for isolated coencapsulation and synergistic release of diverse incompatible components. The multicompartmental capsules exhibit distinct compartments, each of which is covered by a distinct part of a heterogeneous shell. The volume and number of multiple compartments can be well-controlled by adjusting flow rates and device numbers for isolated and optimized encapsulation of different components, while the composition of different part of the heterogeneous shell can be individually tailored by changing the composition of droplet template for flexibly tuning the release behavior of each component. Two combined devices are first used to fabricate dual-compartmental capsules and then scaled up to fabricate more complex triple-compartmental capsules for coencapsulation. The synergistic release properties are demonstrated by using dual-compartmental capsules, which contain one-half shell with a constant release rate and the other half shell with a temperature-dependent release rate. Such a heterogeneous shell provides more flexibilities for synergistic release with controllable release sequence and release rates to achieve advanced and optimized synergistic efficacy. The multicompartmental capsules show high potential for applications such as drug codelivery, confined reactions, enzyme immobilizations, and cell cultures. PMID:26977710

  20. A site-specific controlled-release system for metformin.

    PubMed

    Di Colo, Giacomo; Zambito, Ylenia; Baggiani, Andrea; Carelli, Vera; Serafini, Maria Francesca

    2005-05-01

    Oral absorption of the antihyperglycaemic agent metformin hydrochloride (MF-HCl) is confined to the upper part of the intestine, therefore rational controlled-release formulations of this drug should ensure a complete release during transit from stomach to jejunum. The aim of this study was the preparation of a system able to sustain release of high MF-HCl doses in compliance with the above requirement. Matrices (6 mm diameter; 50 mg weight) comprising varying drug-Precirol ATO 5 ratios were prepared by compression. The matrix containing 70% drug was coated on one face with Eudragit L100-55. Drug release to simulated gastric (SGF), jejunal (SJF) and ileal (SIF) fluids in sequence was studied using a modified USP rotating basket method. Release depended on drug load whereas it was independent of dissolution medium pH and hydrodynamics. Release kinetics were of radical t type and were determined by drug diffusion in aqueous pores created in the matrix by drug dissolution. An equation correlating rate-determining factors was developed, whereby the release pattern could be optimized. The half-coated matrix started release in SGF and completed it in SJF. The half-coated matrix, synchronizing drug release and matrix transit across the small intestine, may improve drug bioavailability and reduce side effects. PMID:15901345

  1. Controlled release of tocopherols from polymer blend films

    NASA Astrophysics Data System (ADS)

    Obinata, Noe

    Controlled release packaging has great potential to increase storage stability of foods by releasing active compounds into foods continuously over time. However, a major limitation in development of this technology is the inability to control the release and provide rates useful for long term storage of foods. Better understanding of the factors affecting active compound release is needed to overcome this limitation. The objective of this research was to investigate the relationship between polymer composition, polymer processing method, polymer morphology, and release properties of active compounds, and to provide proof of principle that compound release is controlled by film morphology. A natural antioxidant, tocopherol was used as a model active compound because it is natural, effective, heat stable, and soluble in most packaging polymers. Polymer blend films were produced from combination of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), polypropylene (PP), or polystyrene (PS) with 3000 ppm mixed tocopherols using conventional blending method and innovative blending method, smart blending with a novel mixer using chaotic advection. Film morphologies were visualized with scanning electron microscopy (SEM). Release of tocopherols into 95% ethanol as a food simulant was measured by UV/Visible spectrophotometry or HPLC, and diffusivity of tocopherols in the polymers was estimated from this data. Polymer composition (blend proportions) and processing methods have major effects on film morphology. Four different types of morphologies, dispersed, co-continuous, fiber, and multilayer structures were developed by either conventional extrusion or smart blending. With smart blending of fixed polymer compositions, different morphologies were progressively developed with fixed polymer composition as the number of rod rotations increased, providing a way to separate effects of polymer composition and morphology. The different morphologies

  2. Modeling controlled nutrient release from polymer coated fertilizers: diffusion release from single granules.

    PubMed

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A comprehensive model describing the complex and "non-Fickian" (mathematically nonlinear) nature of the release from single granules of membrane coated, controlled release fertilizers (CRFs) is proposed consisting of three stages: i. a lag period during which water penetrates the coating of the granule dissolving part of the solid fertilizer in it ii. a period of linear release during which water penetration into and release out occur concomitantly while the total volume of the granules remains practically constant; and iii. a period of "decaying release", starting as the concentration inside the granule starts to decrease. A mathematical model was developed based on vapor and nutrient diffusion equations. The model predicts the release stages in terms of measurable geometrical and chemophysical parameters such as the following: the product of granule radius and coating thickness, water and solute permeability, saturation concentration of the fertilizer, and its density. The model successfully predicts the complex and "sigmoidal" pattern of release that is essential for matching plant temporal demand to ensure high agronomic and environmental effectiveness. It also lends itself to more complex statistical formulations which account for the large variability within large populations of coated CRFs and can serve for further improving CRF production and performance. PMID:12785532

  3. Design and characterization of controlled release gastro-retentive floating tablet of an atypical psychotropic agent

    PubMed Central

    Ukawala, Ravikumar; Singhvi, Gautam; Jain, Suresh; Shukla, Vipin; Yadav, Nilesh; Sharma, Sohiny

    2012-01-01

    The purpose of the present work was to design and evaluate the once daily sustained release matrix type gastro-retentive floating tablet of Quetiapine Fumarate base on hydrophilic matrices of HPMC, sodium CMC and Carbopol. Sodium bicarbonate was incorporated as a gas-generating agent to give buoyancy. In-vitro drug release studies were performed in pH 1.2 buffer using USP type II paddle at 50 rpm. The release rate of drug decreased with increasing polymer proportion of HPMC K15M from 20 to 60 mg. Formulation with desired drug release achieved with combination of sodium CMC and K15M in ratio of 1:3. The drug release mechanism was predominantly found to be Non-Fickian diffusion and Higuchi controlled. PMID:23066221

  4. Magnetic molecularly imprinted polymer for aspirin recognition and controlled release

    NASA Astrophysics Data System (ADS)

    Kan, Xianwen; Geng, Zhirong; Zhao, Yao; Wang, Zhilin; Zhu, Jun-Jie

    2009-04-01

    Core-shell structural magnetic molecularly imprinted polymers (magnetic MIPs) with combined properties of molecular recognition and controlled release were prepared and characterized. Magnetic MIPs were synthesized by the co-polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) around aspirin (ASP) at the surface of double-bond-functionalized Fe3O4 nanoparticles in chloroform. The obtained spherical magnetic MIPs with diameters of about 500 nm had obvious superparamagnetism and could be separated quickly by an external magnetic field. Binding experiments were carried out to evaluate the properties of magnetic MIPs and magnetic non-molecularly imprinted polymers (magnetic NIPs). The results demonstrated that the magnetic MIPs had high adsorption capacity and selectivity to ASP. Moreover, release profiles and release rate of ASP from the ASP-loaded magnetic MIPs indicated that the magnetic MIPs also had potential applications in drug controlled release.

  5. Liquid phase coating to produce controlled-release alginate microspheres.

    PubMed

    Chan, Lai Wah; Liu, Xiaohua; Heng, Paul Wan Sia

    2005-12-01

    This study explored a liquid phase coating technique to produce polymethyl methacrylate (PMMA)-coated alginate microspheres. Alginate microspheres with a mean diameter of 85.6 microm were prepared using an emulsification method. The alginate microspheres, as cores, were then coated with different types of PMMA by a liquid phase coating technique. The release characteristics of these coated microspheres in simulated gastric (SGF) and intestinal (SIF) fluids and the influence of drug load on encapsulation efficiency were studied. The release of paracetamol, as a model hydrophilic drug, from the coated microspheres in SGF and SIF was greatly retarded. Release rates of Eudragit RS100-coated microspheres in SGF and SIF were similar as the rate-controlling polymer coat was insoluble in both media. Drug release from Eudragit S100-coated microspheres was more sustained in SGF than in SIF, due to the greater solubility of the coating polymer in media with pH greater than 7.0. The drug release rate was affected by the core:coat ratio. Drug release from the coated microspheres was best described by the Higuchi's square root model. The liquid phase coating technique developed offers an efficient method of coating small microspheres with markedly reduced drug loss and possible controlled drug release. PMID:16423760

  6. Controlled release of diclofenac sodium in glycolipid incorporated micro emulsions.

    PubMed

    Premarathne, E P N; Karunaratne, D N; Perera, A D L Chandani

    2016-09-25

    The effect of the glycolipid, hexadecyl-β-d-glucopyranoside, incorporated in microemulsions (ME(1)) towards the enhancement of skin absorption and skin permeation of Diclofenac sodium (DS(2)) was evaluated. A Franz diffusion cell with a piece of pig's ear epidermis indicated that the optimized ME formulation with glycolipid (0.05wt%) exhibited significantly higher permeability than the conventional formulations. The releasing profiles of DS from ME formulations exhibited first order release kinetics resembling a diffusion controlled release model for the first 8h. Incorporating hexadecyl-β-D glucopyranoside in ME formulations shows significant potential as a delivery vehicle in the cosmetics and pharmaceutical industry. PMID:27477103

  7. Lipophilic nalmefene prodrugs to achieve a one-month sustained release.

    PubMed

    Gaekens, Tim; Guillaume, Michel; Borghys, Herman; De Zwart, Loeckie L; de Vries, Ronald; Embrechts, Roger C A; Vermeulen, An; Megens, Anton A H P; Leysen, Josée E; Herdewijn, Piet; Annaert, Pieter P; Atack, John R

    2016-06-28

    Nalmefene is an opioid antagonist which as a once-a-day tablet formulation has recently been approved for reducing ethanol intake in alcoholic subjects. In order to address the compliance issue in this patient population, a number of potential nalmefene prodrugs were synthesized with the aim of providing a formulation that could provide plasma drug concentrations in the region of 0.5-1.0ng/mL for a one-month period when dosed intramuscular to dogs or minipigs. In an initial series of studies, three different lipophilic nalmefene derivatives were evaluated: the palmitate (C16), the octadecyl glutarate diester (C18-C5) and the decyl carbamate (CB10). They were administered intramuscularly to dogs in a sesame oil solution at a dose of 1mg-eq. nalmefene/kg. The decyl carbamate was released relatively quickly from the oil depot and its carbamate bond was too stable to be used as a prodrug. The other two derivatives delivered a fairly constant level of 0.2-0.3ng nalmefene/mL plasma for one month and since there was no significant difference between these two, the less complex palmitate monoester was chosen to demonstrate that dog plasma nalmefene concentrations were dose-dependent at 1, 5 and 20mg-eq. nalmefene/kg. In a second set of experiments, the effect of the chain length of the fatty acid monoester promoieties was examined. The increasingly lipophilic octanoate (C8), decanoate (C10) and dodecanoate (C12) derivatives were evaluated in dogs and in minipigs, at a dose of 5mg-eq. nalmefene/kg and plasma nalmefene concentrations were measured over a four-week period. The pharmacokinetic profiles were very similar in both species with Cmax decreasing and Tmax increasing with increasing fatty acid chain length and the target plasma concentrations (0.5-1.0ng/mL over a month-long period) were achieved with the dodecanoate (C12) prodrug. These data therefore demonstrate that sustained plasma nalmefene concentrations can be achieved in both dog and minipig using nalmefene

  8. Formulation of controlled release gellan gum macro beads of amoxicillin.

    PubMed

    Babu, R Jayachandra; Sathigari, Sateesh; Kumar, M Thilek; Pandit, J K

    2010-01-01

    Gellan gum has been reported to have wide pharmaceutical applications such as tablet binder, disintegrant, gelling agent and as a controlled release polymer. Multiparticulate delivery systems spread out more uniformly in the gastrointestinal tract and reduce the local irritation. The purpose of this study is to explore possible applicability of gellan macro beads as an oral controlled release system of a sparingly soluble drug, amoxicillin. Gellan gum beads were prepared by ionotropic gelation with calcium ions. The effect of drug loading, stirring time, polymer concentration, electrolyte (CaCl2) concentration, curing time etc. influencing the preparation of the gellan gum macro beads and the drug release from gellan gum beads were investigated in this study. Optimal preparation conditions allowed very high incorporation efficiency for amoxicillin (91%) The release kinetics of amoxicillin from gellan beads followed the diffusion model for an inert porous matrix in the order: 0.1 N HCl > phosphate buffer > distilled water. Change in curing time did not significantly affect the release rate constant, but drug concentration, polymer concentration and electrolyte concentration significantly affect the release rate of amoxicillin from the beads. The gellan macro beads may be suitable for gastro retentive controlled delivery of amoxicillin. PMID:19863487

  9. Optogenetic control of striatal dopamine release in rats

    PubMed Central

    Bass, Caroline E; Grinevich, Valentina P; Vance, Zachary B; Sullivan, Ryan P; Bonin, Keith D; Budygin, Evgeny A

    2010-01-01

    Optogenetic control over neuronal firing has become an increasingly elegant method to dissect the microcircuitry of mammalian brains. To date, examination of these manipulations on neurotransmitter release has been minimal. Here we present the first in-depth analysis of optogenetic stimulation on dopamine neurotransmission in the dorsal striatum of urethane-anesthetized rats. By combining the tight spatial and temporal resolution of both optogenetics and fast-scan cyclic voltammetry we have determined the parameters necessary to control phasic dopamine release in the dorsal striatum of rats in vivo. The kinetics of optically induced dopamine release mirror established models of electrically evoked release, indicating that potential artifacts of electrical stimulation on ion channels and the dopamine transporter are negligible. Furthermore a lack of change in extracellular pH indicates that optical stimulation does not alter blood flow. Optical control over dopamine release is highly reproducible and flexible. We are able to repeatedly evoke concentrations of dopamine release as small as a single dopamine transient (50 nM). A U-shaped frequency response curve exists with maximal stimulation inducing dopamine effluxes exceeding 500 nM. Taken together, these results have obvious implications for understanding the neurobiological basis of dopaminergic-based disorders and provide the framework to effectively manipulate dopamine patterns. PMID:20534006

  10. Controlled release of a hydrophilic drug from coaxially electrospun polycaprolactone nanofibers.

    PubMed

    Sultanova, Zahida; Kaleli, Gizem; Kabay, Gözde; Mutlu, Mehmet

    2016-05-30

    A recent approach for controlled release of drugs is the production of core-shell fibers via modified coaxial electrospinning where a shell solution which is not fully electrospinnable can be used. In this study, this technique was used for achieving the controlled release of a model hydrophilic drug (ampicillin) which is known to have a low compatibility with the polymer (polycaprolactone). A partially electrospinnable shell fluid (4% (w/v) polycaprolactone (PCL) solution) and a fully electrospinnable core fluid (10% (w/v) PCL, 2% (w/v) ampicillin solution) were used in order to create ampicillin-loaded PCL nanofibers covered by a PCL shield. Scanning electron microscopy and optical microscopy images proved that the membranes have core-shell structured nanofibers. Fourier transform infrared spectroscopy demonstrated that some compatibility might be present between ampicillin and PCL. Finally, drug release studies showed that the drug release kinetics of core-shell products is closer to zero-order kinetics while the drug release kinetics of single electrospinning of the core resulted with serious burst release. Together, these imply that the application area of modified coaxial electrospinning in controlled release could be expanded to polymers and drugs with low compatibility. PMID:27012983

  11. Antimicrobial beeswax coated polylactide films with silver control release capacity.

    PubMed

    Martínez-Abad, Antonio; Lagarón, Jose Maria; Ocio, María Jose

    2014-03-17

    Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrated a high burst release which in some instances implied surpassing some current migration restrictions (<0.05mg/kg food), the addition of a beeswax layer allowed a sustained release of the antimicrobial compound. Increasing the thickness of the beeswax layer resulted in an increase in the water barrier properties of the films while reducing the relatively constant values of sustained release. Antimicrobial performance was correlated with the release of silver ions, indicating threshold concentrations for biocide action of <6μg/L and 9-14μg/L for surface contact and in liquid media, respectively. Either by surface contact or by immersion in growth medium or vegetable soup, the coated films displayed a strong bactericidal effect against Salmonella enterica. The application of this functional barrier thus offers the possibility of tuning the release profiles of the films to suit a specific application and puts forth the possible suitability of these materials for food packaging or other migration sensitive applications. PMID:24448276

  12. Sol-gel encapsulation for controlled drug release and biosensing

    NASA Astrophysics Data System (ADS)

    Fang, Jonathan

    The main focus of this dissertation is to investigate the use of sol-gel encapsulation of biomolecules for controlled drug release and biosensing. Controlled drug release has advantages over conventional therapies in that it maintains a constant, therapeutic drug level in the body for prolonged periods of time. The anti-hypertensive drug Captopril was encapsulated in sol-gel materials of various forms, such as silica xerogels and nanoparticles. The primary objective was to show that sol-gel silica materials are promising drug carriers for controlled release by releasing Captopril at a release rate that is within a therapeutic range. We were able to demonstrate desired release for over a week from Captopril-doped silica xerogels and overall release from Captopril-doped silica nanoparticles. As an aside, the antibiotic Vancomycin was also encapsulated in these porous silica nanoparticles and desired release was obtained for several days in-vitro. The second part of the dissertation focuses on immobilizing antibodies and proteins in sol-gel to detect various analytes, such as hormones and amino acids. Sol-gel competitive immunoassays on antibody-doped silica xerogels were used for hormone detection. Calibration for insulin and C-peptide in standard solutions was obtained in the nM range. In addition, NASA-Ames is also interested in developing a reagentless biosensor using bacterial periplasmic binding proteins (bPBPs) to detect specific biomarkers, such as amino acids and phosphate. These bPBPs were doubly labeled with two different fluorophores and encapsulated in silica xerogels. Ligand-binding experiments were performed on the bPBPs in solution and in sol-gel. Ligand-binding was monitored by fluorescence resonance energy transfer (FRET) between the two fluorophores on the bPBP. Titration data show that one bPBP has retained its ligand-binding properties in sol-gel.

  13. Continuous nanostructures for the controlled release of drugs.

    PubMed

    Venugopal, J; Prabhakaran, Molamma P; Low, Sharon; Choon, Aw Tar; Deepika, G; Dev, V R Giri; Ramakrishna, S

    2009-01-01

    The annual world wide market for controlled release of polymer systems which extends beyond drug delivery is now estimated to $60 billion and these systems are used by over 100 million people each year. It was estimated that drug delivery will play a pivotal role in approximately 40% of all pharmaceutical sales in near future. Novel methods of drug delivery will not only result in more effective and efficacious treatments but also generates new niche markets to provide greater intellectual property protection to already existing drug formulations. Recently, biodegradable electrospun polymer nanofibrous substrate as drug carrier seems to be a promising method for delivering anticancer drugs, especially in postoperative local chemotherapy. Alternatively drug release can be triggered by the environment or other external events such as changes in pH, temperature, or the presence of analyte such as glucose. In general, controlled release of polymer systems delivering drugs in the optimum dosage for long periods is to increase the efficacy of drug, reducing patient compliance. Recent research for the use of nanotechnology (nanoparticle and nanofibers) in drug delivery suggests that the technology might solve problems in the areas such as controlled release, various topical administration, gut absorption and targeted systemic delivery. This review article described the applications of polymer nanoparticles and nanofibers for loading potential drugs for the controlled release to target incurable diseases. PMID:19442191

  14. Controlled Release of Ciprofloxacin from Core-Shell Nanofibers with Monolithic or Blended Core.

    PubMed

    Zupančič, Špela; Sinha-Ray, Sumit; Sinha-Ray, Suman; Kristl, Julijana; Yarin, Alexander L

    2016-04-01

    Sustained controlled drug release is one of the prominent contributions for more successful treatment outcomes in the case of several diseases. However, the incorporation of hydrophilic drugs into nanofibers, a promising novel delivery system, and achieving a long-term sustained release still pose a challenging task. In this work we demonstrated a robust method of avoiding burst release of drugs and achieving a sustained drug release from 2 to 4 weeks using core-shell nanofibers with poly(methyl methacrylate) (PMMA) shell and monolithic poly(vinyl alcohol) (PVA) core or a novel type of core-shell nanofibers with blended (PVA and PMMA) core loaded with ciprofloxacin hydrochloride (CIP). It is also shown that, for core-shell nanofibers with monolithic core, drug release can be manipulated by varying flow rate of the core PVA solution, whereas for core-shell nanofibers with blended core, drug release can be manipulated by varying the ratios between PMMA and PVA in the core. During coaxial electrospinning, when the solvent from the core evaporates in concert with the solvent from the shell, the interconnected pores spanning the core and the shell are formed. The release process is found to be desorption-limited and agrees with the two-stage desorption model. Ciprofloxacin-loaded nanofiber mats developed in the present work could be potentially used as local drug delivery systems for treatment of several medical conditions, including periodontal disease and skin, bone, and joint infections. PMID:26950163

  15. Understanding and managing the impact of HPMC variability on drug release from controlled release formulations.

    PubMed

    Zhou, Deliang; Law, Devalina; Reynolds, Judie; Davis, Lynn; Smith, Clifford; Torres, Jose L; Dave, Viraj; Gopinathan, Nishanth; Hernandez, Daniel T; Springman, Mary Kay; Zhou, Casey Chun

    2014-06-01

    The purpose of this study is to identify critical physicochemical properties of hydroxypxropyl methylcellulose (HPMC) that impact the dissolution of a controlled release tablet and develop a strategy to mitigate the HPMC lot-to-lot and vendor-to-vendor variability. A screening experiment was performed to evaluate the impacts of methoxy/hydroxypropyl substitutions, and viscosity on drug release. The chemical diversity of HPMC was explored by nuclear magnetic resonance (NMR), and the erosion rate of HPMC was investigated using various dissolution apparatuses. Statistical evaluation suggested that the hydroxypropyl content was the primary factor impacting the drug release. However, the statistical model prediction was not robust. NMR experiments suggested the existence of structural diversity of HPMC between lots and more significantly between vendors. Review of drug release from hydrophilic matrices indicated that erosion is a key aspect for both poorly soluble and soluble drugs. An erosion rate method was then developed, which enabled the establishment of a robust model and a meaningful HPMC specification. The study revealed that the overall substitution level is not the unique parameter that dictates its release-controlling properties. Fundamental principles of polymer chemistry and dissolution mechanisms are important in the development and manufacturing of hydrophilic matrices with consistent dissolution performance. PMID:24652662

  16. Application of controlled nutrient release to permeable reactive barriers.

    PubMed

    Freidman, Benjamin L; Gras, Sally L; Snape, Ian; Stevens, Geoff W; Mumford, Kathryn A

    2016-03-15

    The application of controlled release nutrient (CRN) materials to permeable reactive barriers to promote biodegradation of petroleum hydrocarbons in groundwater was investigated. The longevity of release, influence of flow velocity and petroleum hydrocarbon concentration on nutrient release was assessed using soluble and ion exchange CRN materials; namely Polyon™ and Zeopro™. Both CRN materials, assessed at 4 °C and 23 °C, demonstrated continuing release of nitrogen, phosphorus and potassium (N-P-K) at 3500 bed volumes passing, with longer timeframes of N-P-K release at 4 °C. Zeopro™-activated carbon mixtures demonstrated depletion of N-P-K prior to 3500 bed volumes passing. Increased flow velocity was shown to lower nutrient concentrations in Polyon™ flow cells while nutrient release from Zeopro™ was largely unchanged. The presence of petroleum hydrocarbons, at 1.08 mmol/L and 3.25 mmol/L toluene, were not shown to alter nutrient release from Polyon™ and Zeopro™ across 14 days. These findings suggest that Polyon™ and Zeopro™ may be suitable CRN materials for application to PRBs in low nutrient environments. PMID:26735866

  17. Wetting mechanisms of gel-based controlled-release fertilizers.

    PubMed

    Shavit, U; Reiss, M; Shaviv, A

    2003-02-14

    The release mechanism of gel-based controlled release fertilizers (CRFs) involves water penetration into dry mixtures of fertilizers and gel forming polymers. Water penetration provides an upper limit to the whole release process. Where wetting prediction is often based on models that describe the flow of the liquid phase, vapor motion may become significant when a sharp wetting front exists. In this study we examine the role of vapor and fluid flows in the wetting process of CRFs consisting of urea or KNO(3) mixed with polyacrylamide (PAM). Vapor adsorption isotherms were obtained for typical fertilizer-PAM mixtures. Wetting and release experiments were conducted by dividing the CRFs into regions alternately filled with a pure fertilizer and mixtures of PAM and fertilizer. The experiments were designed in such a way that when the wetting front reaches a mixtures interface, its motion depends on the gradient imposed by the difference in osmotic potential (OP). The coupled equations of vapor and liquid flow in initially dry conditions were solved numerically to demonstrate the conceptual understanding gained by the experiments. The results show that wetting front motion is affected by transport and adsorption of vapor. It was also shown that the release rate is different when wetting is governed by vapor flow or by liquid flow. The release pattern from a multi-regions device was consistent with the wetting pattern, demonstrating the possibility to tailor the release according to periods of peak demand. PMID:12586505

  18. Optically guided controlled release from liposomes with tunable plasmonic nanobubbles.

    PubMed

    Anderson, Lindsey J E; Hansen, Eric; Lukianova-Hleb, Ekaterina Y; Hafner, Jason H; Lapotko, Dmitri O

    2010-06-01

    A new method of optically guided controlled release was experimentally evaluated with liposomes containing a molecular load and gold nanoparticles (NPs). NPs were exposed to short laser pulses to induce transient vapor bubbles around the NPs, plasmonic nanobubbles, in order to disrupt the liposome and eject its molecular contents. The release efficacy was tuned by varying the lifetime and size of the nanobubble with the fluence of the laser pulse. Optical scattering by nanobubbles correlated to the molecular release and was used to guide the release. The release of two fluorescent proteins from individual liposomes has been directly monitored by fluorescence microscopy, while the generation of the plasmonic nanobubbles was imaged and measured with optical scattering techniques. Plasmonic nanobubble-induced release was found to be a mechanical, nonthermal process that requires a single laser pulse and ejects the liposome contents within a millisecond timescale without damage to the molecular cargo and that can be controlled through the fluence of laser pulse. PMID:20156498

  19. Optically Guided Controlled Release from Liposomes With Tunable Plasmonic Nanobubbles

    PubMed Central

    Anderson, Lindsey; Hansen, Eric; Lukianova-Hleb, Ekaterina Y.; Hafner, Jason H.; Lapotko, Dmitri O.

    2010-01-01

    A new method of optically guided controlled release was experimentally evaluated with liposomes containing a molecular load and gold nanoparticles (NPs). NPs were exposed to short laser pulses to induce transient vapor bubbles around the NPs, plasmonic nanobubbles, in order to disrupt the liposome and eject its molecular contents. The release efficacy was tuned by varying the lifetime and size of the nanobubble with the fluence of the laser pulse. Optical scattering by nanobubbles correlated to the molecular release and was used to guide the release. The release of two fluorescent proteins from individual liposomes has been directly monitored by fluorescence microscopy, while the generation of the plasmonic nanobubbles was imaged and measured with optical scattering techniques. Plasmonic nanobubble-induced release was found to be a mechanical, nonthermal process that requires a single laser pulse and ejects of the liposome contents within a millisecond timescale without damage to the molecular cargo and that can be controlled through the fluence of laser pulse. PMID:20156498

  20. Method and apparatus for controlling accidental releases of tritium

    DOEpatents

    Galloway, Terry R. [Berkeley, CA

    1980-04-01

    An improvement in a tritium control system based on a catalytic oxidation reactor wherein accidental releases of tritium into room air are controlled by flooding the catalytic oxidation reactor with hydrogen when the tritium concentration in the room air exceeds a specified limit. The sudden flooding with hydrogen heats the catalyst to a high temperature within seconds, thereby greatly increasing the catalytic oxidation rate of tritium to tritiated water vapor. Thus, the catalyst is heated only when needed. In addition to the heating effect, the hydrogen flow also swamps the tritium and further reduces the tritium release.

  1. Method and apparatus for controlling accidental releases of tritium

    DOEpatents

    Galloway, T.R.

    1980-04-01

    An improvement is described in a tritium control system based on a catalytic oxidation reactor wherein accidental releases of tritium into room air are controlled by flooding the catalytic oxidation reactor with hydrogen when the tritium concentration in the room air exceeds a specified limit. The sudden flooding with hydrogen heats the catalyst to a high temperature within seconds, thereby greatly increasing the catalytic oxidation rate of tritium to tritiated water vapor. Thus, the catalyst is heated only when needed. In addition to the heating effect, the hydrogen flow also swamps the tritium and further reduces the tritium release. 1 fig.

  2. The control of calcium release in heart muscle.

    PubMed

    Cannell, M B; Cheng, H; Lederer, W J

    1995-05-19

    The control of calcium release from intracellular stores (the sarcoplasmic reticulum) in cardiac muscle was examined with the use of a confocal microscope and voltage clamp techniques. Depolarization evoked graded calcium release by altering the extent of spatial and temporal summation of elementary calcium release events called "calcium sparks." These evoked sparks were triggered by local L-type calcium channel currents in a stochastic manner, were similar at different potentials, and resembled spontaneous calcium sparks. Once triggered, the calcium release from the sarcoplasmic reticulum during a calcium spark was independent of the duration of the triggering calcium influx. These results were used to develop a unifying model for cardiac excitation-contraction coupling that explains the large (but paradoxically stable) amplification of the trigger calcium influx by a combination of digital and analog behavior. PMID:7754384

  3. Application of cellulose acetate for controlled release of thymol.

    PubMed

    Milovanovic, Stoja; Markovic, Darka; Aksentijevic, Ksenija; Stojanovic, Dusica B; Ivanovic, Jasna; Zizovic, Irena

    2016-08-20

    Cellulose acetate (CA) was investigated as a carrier towards development of material with controlled release of thymol as a natural substance with strong antibacterial properties using high pressure techniques. Effect of thymol content on CA was confirmed by SEM, FTIR and DSC methods. Kinetic of thymol release from CA was tested using simulated gastric and intestinal fluids (hydrochloric acid and phosphate buffer saline). Results were correlated with Korsmeyer-Peppas and Weibull model. Depending on the thymol content and chemical nature of the release medium, the time of thymol release varied from one to three days indicating CA as a promising carrier of thymol with potential uses from medicine to agriculture. The impregnated CA showed antibacterial activity against 23 tested bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA) which is particularly important bearing in mind that this strain causes fatal infections in humans and animals. PMID:27178940

  4. Advances in mechanistic understanding of release rate control mechanisms of extended-release hydrophilic matrix tablets.

    PubMed

    Timmins, Peter; Desai, Divyakant; Chen, Wei; Wray, Patrick; Brown, Jonathan; Hanley, Sarah

    2016-08-01

    Approaches to characterizing and developing understanding around the mechanisms that control the release of drugs from hydrophilic matrix tablets are reviewed. While historical context is provided and direct physical characterization methods are described, recent advances including the role of percolation thresholds, the application on magnetic resonance and other spectroscopic imaging techniques are considered. The influence of polymer and dosage form characteristics are reviewed. The utility of mathematical modeling is described. Finally, how all the information derived from applying the developed mechanistic understanding from all of these tools can be brought together to develop a robust and reliable hydrophilic matrix extended-release tablet formulation is proposed. PMID:27444495

  5. Motor control differs for increasing and releasing force.

    PubMed

    Park, Seoung Hoon; Kwon, MinHyuk; Solis, Danielle; Lodha, Neha; Christou, Evangelos A

    2016-06-01

    Control of the motor output depends on our ability to precisely increase and release force. However, the influence of aging on force increase and release remains unknown. The purpose of this study, therefore, was to determine whether force control differs while increasing and releasing force in young and older adults. Sixteen young adults (22.5 ± 4 yr, 8 females) and 16 older adults (75.7 ± 6.4 yr, 8 females) increased and released force at a constant rate (10% maximum voluntary contraction force/s) during an ankle dorsiflexion isometric task. We recorded the force output and multiple motor unit activity from the tibialis anterior (TA) muscle and quantified the following outcomes: 1) variability of force using the SD of force; 2) mean discharge rate and variability of discharge rate of multiple motor units; and 3) power spectrum of the multiple motor units from 0-4, 4-10, 10-35, and 35-60 Hz. Participants exhibited greater force variability while releasing force, independent of age (P < 0.001). Increased force variability during force release was associated with decreased modulation of multiple motor units from 35 to 60 Hz (R(2) = 0.38). Modulation of multiple motor units from 35 to 60 Hz was further correlated to the change in mean discharge rate of multiple motor units (r = 0.66) and modulation from 0 to 4 Hz (r = -0.64). In conclusion, these findings suggest that force control is altered while releasing due to an altered modulation of the motor units. PMID:26961104

  6. Controlled release of dual drugs from emulsion electrospun nanofibrous mats.

    PubMed

    Yan, Su; Xiaoqiang, Li; Shuiping, Liu; Xiumei, Mo; Ramakrishna, Seeram

    2009-10-15

    The purpose of this work is to develop a novel type of tissue engineering scaffold or drugs delivery carrier with the capability of encapsulation and controlled release drugs. In this study, Rhodamine B and Bovine Serum Albumin (BSA) were successfully incorporated into nanofibers by means of emulsion electrospinning. The morphology of composite nanofibers was studied by Scanning Electron Microscopy (SEM). The composite nanofibrous mats made from emulsion electrospinning were characterized by water contact angle measurement and X-ray diffraction. In vitro dual drugs release behaviors from composite nanofibrous mats were investigated. The results indicated that the incorporated drug and/or proteins in composite fibrous mats made from electrospinning could be control released by adjusting the processes of emulsions preparation. PMID:19586756

  7. Magnetic Compression of Polyelectrolyte Microcapsules for Controlled Release.

    PubMed

    Hu, Yanan; Liu, Chuanyong; Li, Dongzhi; Long, Yue; Song, Kai; Tung, Chen-Ho

    2015-10-20

    In this study, microcapsules with a magnetic particle as the core and polyelectrolyte multilayers as the shell were fabricated. The cavity of the microcapsules was created by etching the SiO2 layer, which was first coated on the magnetic core particle, and the size of the cavity can be adjusted by the thickness of the SiO2 layer. This magnetically responsive microcapsule deforms upon application of a constant magnetic field and results in the release of the core content, and the release velocity could be controlled by the strength of the magnetic field. This release mechanism is proactive and repeatable, combined with its localized and remote controllability; it can be a powerful tool for delivering medical agents on site. PMID:26402037

  8. Use of controlled release herbicides in waste burial sites

    SciTech Connect

    Burton, F.G.; Cataldo, D.A.; Cline, J.F.; Skiens, W.E.

    1981-07-01

    Controlled-release formulations of herbicides have been applied to the soil in the manner traditional for herbicides: on the surface or mixed into the top few inches of soil. The controlled-release formulation allows another option that we propose to use: to place herbicides, contained in controlled-release formulations, in a layer at least a foot below the surface of the soil, in order to prevent root penetration below that level. Ideally, the herbicide will prevent root tip cell division but will not translocate within the plant, thus assuring that the plant will survive, preserving the ground cover. Trifluralin is one of the herbicides which does not translocate and was chosen for use in this study. A number of applications for this technology are possible; particularly in waste management. In the present studies, we used two different forms of polymeric carrier/delivery (PCD) systems to investigate the controlled release of herbicides. In the initial study, a sheet was made of homogeneous mixtures of an individual polymer and trifluralin. We made several of these sheets, using a different polymer each time (with trifluralin) to compare release rates from the various polymers. We also fabricated cylindrical pellets in two sizes from mixtures of Profax/sup a/ PS-1600 polypropylene and trifluralin, formulated to determine the interaction of PCD systems with soil. Also developed is a trifluralin-releasing device with a theoretical effective lifetime approaching 100 years. The system was designed specifically to protect the asphalt layer or clay/aggregate barriers on uranium mill tailings piles. PCD devices composed of pellets could also be implanted over burial sites for radioactive and/or toxic materials, preventing translocation of those materials to plant shoots, and thence into the biosphere.

  9. Preparation of TiO2 nanotubes/mesoporous calcium silicate composites with controllable drug release.

    PubMed

    Xie, Chunling; Li, Ping; Liu, Yan; Luo, Fei; Xiao, Xiufeng

    2016-10-01

    Nanotube structures such as TiO2 nanotube (TNT) arrays produced by self-ordering electrochemical anodization have been extensively explored for drug delivery applications. In this study, we presented a new implantable drug delivery system that combined mesoporous calcium silicate coating with nanotube structures to achieve a controllable drug release of water soluble and antiphlogistic drug loxoprofen sodium. The results showed that the TiO2 nanotubes/mesoporous calcium silicate composites were successfully fabricated by a simple template method and the deposition of mesoporous calcium silicate increased with the soaking time. Moreover, the rate of deposition of biological mesoporous calcium silicate on amorphous TNTs was better than that on anatase TNTs. Further, zinc-incorporated mesoporous calcium silicate coating, produced by adding a certain concentration of zinc nitrate into the soaking system, displayed improved chemical stability. A significant improvement in the drug release characteristics with reduced burst release and sustained release was demonstrated. PMID:27287140

  10. CONTROLLED RELEASE, BLIND TEST OF DNAPL REMEDIATION BY ETHANOL FLUSHING

    EPA Science Inventory

    A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile
    isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL
    remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedia...

  11. 28 CFR 541.68 - Release from controlled housing status.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Release from controlled housing status. 541.68 Section 541.68 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Procedures for Handling of HIV Positive Inmates...

  12. 28 CFR 541.68 - Release from controlled housing status.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Release from controlled housing status. 541.68 Section 541.68 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Procedures for Handling of HIV Positive Inmates...

  13. 28 CFR 541.68 - Release from controlled housing status.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Release from controlled housing status. 541.68 Section 541.68 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Procedures for Handling of HIV Positive Inmates...

  14. 28 CFR 541.68 - Release from controlled housing status.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Release from controlled housing status. 541.68 Section 541.68 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Procedures for Handling of HIV Positive Inmates...

  15. 28 CFR 541.68 - Release from controlled housing status.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Release from controlled housing status. 541.68 Section 541.68 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT INMATE DISCIPLINE AND SPECIAL HOUSING UNITS Procedures for Handling of HIV Positive Inmates...

  16. Biopolymers in controlled release devices for agricultural applications.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of biopolymers such as starch for agricultural applications including controlled release devices is growing due the environmental benefits. Recently, concerns have grown about the worldwide spread of parasitic mites (Varroa destructor) that infect colonies of honey bees (Apis mellifera L.). ...

  17. Using Randomized Controlled Trials to Evaluate Interventions for Releasing Prisoners

    ERIC Educational Resources Information Center

    Pettus-Davis, Carrie; Howard, Matthew Owen; Dunnigan, Allison; Scheyett, Anna M.; Roberts-Lewis, Amelia

    2016-01-01

    Randomized controlled trials (RCTs) are rarely used to evaluate social and behavioral interventions designed for releasing prisoners. Objective: We use a pilot RCT of a social support intervention (Support Matters) as a case example to discuss obstacles and strategies for conducting RCT intervention evaluations that span prison and community…

  18. Thermosensitive liposomes entrapping iron oxide nanoparticles for controllable drug release.

    PubMed

    Tai, Lin-Ai; Tsai, Pi-Ju; Wang, Yu-Chao; Wang, Yu-Jing; Lo, Leu-Wei; Yang, Chung-Shi

    2009-04-01

    Iron oxide nanoparticles can serve as a heating source upon alternative magnetic field (AMF) exposure. Iron oxide nanoparticles can be mixed with thermosensitive nanovehicles for hyperthermia-induced drug release, yet such a design and mechanism may not be suitable for controllable drug release applications in which the tissues are susceptible to environmental temperature change such as brain tissue. In the present study, iron oxide nanoparticles were entrapped inside of thermosensitive liposomes for AMF-induced drug release while the environmental temperature was maintained at a constant level. Carboxyfluorescein was co-entrapped with the iron oxide nanoparticles in the liposomes as a model compound for monitoring drug release and environmental temperature was maintained with a water circulator jacket. These experiments have been successfully performed in solution, in phantom and in anesthetized animals. Furthermore, the thermosensitive liposomes were administered into rat forearm skeletal muscle, and the release of carboxylfluorescein triggered by the external alternative magnetic field was monitored by an implanted microdialysis perfusion probe with an on-line laser-induced fluorescence detector. In the future such a device could be applied to simultaneous magnetic resonance imaging and non-invasive drug release in temperature-sensitive applications. PMID:19420485

  19. Controlled release tablet formulation containing natural Δ(9)-tetrahydrocannabinol.

    PubMed

    Punyamurthula, Nagendra S; Hingorani, Tushar; Adelli, Goutham; Gul, Waseem; ElSohly, Mahmoud A; Repka, Michael A; Majumdar, Soumyajit

    2016-07-01

    Cannabinoids are increasingly being used in the treatment of chemotherapy-induced nausea and vomiting (CINV) because of their action on the cannabinoid receptors, CB1 and CB2. The currently marketed capsule formulations (sesame oil based and crystalline powder) are required to be administered frequently to maintain therapeutic levels, which leads to non-compliance. In the present study, oral controlled release tablet formulations of Δ(9)-tetrahydrocannabinol (THC) were prepared using the lipids Precirol® and Compritol®. Release profiles using THC-lipid matrices and/or with the lipids in the external phase (blend) were evaluated. The effect of directly compressible diluents lactose mixture (Ludipress®), dicalcium phosphate anhydrous (Emcompress®) and microcrystalline cellulose (Avicel® 102) on tablet characteristics and in vitro drug release was also investigated. Further, in vitro THC release in the presence of a lipase inhibitor, Pluronic® F68, was also studied. A 24 h zero-order THC release profile was obtained with a combination of Precirol® and Compritol® in the compression blend. Addition of Pluronic® F68 did not alter THC release in vitro. These optimized tablets were chemically and physically stable for 3 months, the last time point tested, at 25 °C/60% RH. The overall results demonstrate the feasibility of preparing oral THC tablets for once a day administration which can improve CINV management. PMID:26585693

  20. Controlled-release scale inhibitor for use in fracturing treatments

    SciTech Connect

    Powell, R.J.; Gdanski, R.D.; McCabe, M.A.; Buster, D.C.

    1995-11-01

    This paper describes results of laboratory and field testing of a solid, controlled-release scale inhibitor for use in fracturing treatments. Laboratory testing with a continuous flow apparatus has yielded inhibitor release rates under dynamic conditions. The inhibitor was tested to determine the minimum inhibitor concentration required to inhibit the formation of CaCO{sub 3}, CaSO{sub 4}, and BaSO{sub 4} scales in a brine. A model to predict the long-term release rate of the inhibitor was developed from data collected on the continuous flow apparatus. Data from treated wells will be compared with predictions of the model. Inhibitor release-rate testing in a continuous-flow apparatus shows that a solid, calcium-magnesium polyphosphate inhibitor has a sustained release profile. Release-rate testing shows that the inhibitor can be used up to 175 F. The inhibitor is compatible with both borate and zirconium crosslinked fracturing fluids and foamed fluids. The effective lifetime of the scale treatment can be predicted based on a model developed from laboratory data. The input variables required for the prediction include: temperature, water production, amount of inhibitor, minimum effective concentration of inhibitor for the specific brine. The model can be used to aid in the design of the scale inhibitor treatment.

  1. Controlled release of alendronate from nitrogen-doped mesoporous carbon

    DOE PAGESBeta

    Saha, Dipendu; Spurri, Amanda; Chen, Jihua; Hensley, Dale K.

    2016-04-13

    With this study, we have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m2/g, total pore volume 0.6 cm3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ~5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 °C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in the media withmore » pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate.« less

  2. Construction of a controlled-release delivery system for pesticides using biodegradable PLA-based microcapsules.

    PubMed

    Liu, Baoxia; Wang, Yan; Yang, Fei; Wang, Xing; Shen, Hong; Cui, Haixin; Wu, Decheng

    2016-08-01

    Conventional pesticides usually need to be used in more than recommended dosages due to their loss and degradation, which results in a large waste of resources and serious environmental pollution. Encapsulation of pesticides in biodegradable carriers is a feasible approach to develop environment-friendly and efficient controlled-release delivery system. In this work, we fabricated three kinds of polylactic acid (PLA) carriers including microspheres, microcapsules, and porous microcapsules for controlled delivery of Lambda-Cyhalothrin (LC) via premix membrane emulsification (PME). The microcapsule delivery system had better water dispersion than the other two systems. Various microcapsules with a high LC contents as much as 40% and tunable sizes from 0.68 to 4.6μm were constructed by manipulating the process parameters. Compared with LC technical and commercial microcapsule formulation, the microcapsule systems showed a significantly sustained release of LC for a longer period. The LC release triggered by LC diffusion and matrix degradation could be optimally regulated by tuning LC contents and particle sizes of the microcapsules. This multi-regulated release capability is of great significance to achieve the precisely controlled release of pesticides. A preliminary bioassay against plutella xylostella revealed that 0.68μm LC-loaded microcapsules with good UV and thermal stability exhibited an activity similar to a commercial microcapsule formulation. These results demonstrated such an aqueous microcapsule delivery system had a great potential to be further explored for developing an effective and environmentally friendly pesticide-release formulation. PMID:27062215

  3. Controlled release of ethylene via polymeric films for food packaging

    NASA Astrophysics Data System (ADS)

    Pisano, Roberto; Bazzano, Marco; Capozzi, Luigi Carlo; Ferri, Ada; Sangermano, Marco

    2015-12-01

    In modern fruit supply chain a common method to trigger ripening is to keep fruits inside special chambers and initiate the ripening process through administration of ethylene. Ethylene is usually administered through cylinders with inadequate control of its final concentration in the chamber. The aim of this study is the development of a new technology to accurately regulate ethylene concentration in the atmosphere where fruits are preserved: a polymeric film, containing an inclusion complex of α-cyclodextrin with ethylene, was developed. The complex was prepared by molecular encapsulation which allows the entrapment of ethylene into the cavity of α-cyclodextrin. After encapsulation, ethylene can be gradually released from the inclusion complex and its release rate can be regulated by temperature and humidity. The inclusion complex was dispersed into a thin polymeric film produced by UV-curing. This method was used because is solvent-free and involves low operating temperature; both conditions are necessary to prevent rapid release of ethylene from the film. The polymeric films were characterized with respect to thermal behaviour, crystalline structure and kinetics of ethylene release, showing that can effectively control the release of ethylene within confined volume.

  4. Controlled release of growth factors for regenerative medicine.

    PubMed

    Liu, Libiao; Zhou, Xinwei; Xu, Yufan; Zhang, Weiming; Liu, Cheng-Hsien; Wang, Xiaohong

    2015-01-01

    How to release growth factors (GFs) scientifically to promote stem cell proliferation and differentiation is one of the most significant research focuses in the field of regenerative medicine. In a controlled release system, growth factors, extracellular matrices or biomaterial carriers, and sometimes stem cells together form a geometric entirety. Biomaterial carriers provide GFs with a support structure to be adhered, immobilized, encapsulated or/and protected. As a unity, the release rate and rhythm of GFs on cells are normally very delicate and precise. Up to now, the best strategy for clinical applications is the combination systems that encapsulate GFs in microspheres, particularly the nano- or micro-encapsulation techniques integrated GFs with biomaterial carriers. In this mini review, we summarize the current progress in GF delivery systems for regenerative medicine and provide an outlook on two main aspects: one is the classes of stem cells and GFs that have been used frequently in regenerative medicine, including their respective application conditions and functions; the other is the controlled GF release systems, in which various GFs are released orderly and continuously without diffusing simply and rapidly, including their respective opportunities and challenges. PMID:25594403

  5. Use of polysulfone in controlled-release NPK fertilizer formulations.

    PubMed

    Tomaszewska, Maria; Jarosiewicz, Anna

    2002-07-31

    Encapsulation of fertilizers in polymeric coatings is a method used to reduce fertilizer losses and to minimize environmental pollution. Polysulfone was used for a coating preparation for soluble NPK granular fertilizer in controlled-release fertilizer formulations. The coatings were formed by the phase inversion technique (wet method). The influence of the polymer concentration in the film-forming solution on the physical properties of the coatings was examined. The coating structure controls the diffusion of the elements from the interior of the fertilizer granule. It was experimentally confirmed that the use of polysulfone as a coating for a soluble fertilizer decreases the release rate of components. Moreover, the release rate of nutrients from coated granules decreases with the decrease of the coating porosity. In the case of coating with 38.5% porosity, prepared from 13.5% polymer solution after 5 h of test, 100% of NH(4)(+) was released, whereas only 19.0% of NH(4)(+) was released after 5 h for the coating with 11% porosity. In addition, coating of fertilizers leads to improvement of handling properties, and the crushing strength of all coated fertilizers was an average 40% higher than that for uncoated NPK fertilizer. PMID:12137488

  6. Controlled release of molecular components of dendrimer/bioactive complexes

    DOEpatents

    Segalman, Daniel J.; Wallace, J. Shield

    1998-01-01

    A method for releasing molecules (guest molecules) from the matrix formed by the structure of another molecule (host molecule) in a controllable manner has been invented. This method has many applications in science and industry. In addition, applications based on such molecular systems may revolutionize significant areas of medicine, in particular the treatment of cancer and of viral infection. Similar effects can also be obtained by controlled fragmentation of a source molecule, where the molecular fragments form the active principle.

  7. Controlled release of molecular components of dendrimer/bioactive complexes

    DOEpatents

    Segalman, D.J.; Wallace, J.S.

    1998-08-18

    A method for releasing molecules (guest molecules) from the matrix formed by the structure of another molecule (host molecule) in a controllable manner has been invented. This method has many applications in science and industry. In addition, applications based on such molecular systems may revolutionize significant areas of medicine, in particular the treatment of cancer and of viral infection. Similar effects can also be obtained by controlled fragmentation of a source molecule, where the molecular fragments form the active principle. 13 figs.

  8. Photocatalytic Degradation of Cell Membrane Coatings for Controlled Drug Release.

    PubMed

    Rao, Lang; Meng, Qian-Fang; Huang, Qinqin; Liu, Pei; Bu, Lin-Lin; Kondamareddy, Kiran Kumar; Guo, Shi-Shang; Liu, Wei; Zhao, Xing-Zhong

    2016-06-01

    Biomimetic cell-membrane-camouflaged particles with desirable features have been widely used for various biomedical applications. However, there are few reports on employing these particles for cancer drug delivery due to the failure of the membrane coatings to be efficiently degraded in the tumor microenvironment which hampers the drug release. In this work, core-shell SiO2 @TiO2 nanoparticles with enhanced photocatalytic activity are used for controlled degradation of surface erythrocyte membrane coatings. The antitumor drug docetaxel is encapsulated into nanocarriers to demonstrate the controlled drug release under ultraviolet irradiation, and the drug-loaded nanoparticles are further used for enhanced cancer cell therapy. Here, a simple but practical method for degradation of cell membrane coatings is presented, and a good feasibility of using cell membrane-coated nanocarriers for controlled drug delivery is demonstrated. PMID:27191802

  9. Carbon monoxide – physiology, detection and controlled release

    PubMed Central

    Heinemann, Stefan H.; Hoshi, Toshinori; Westerhausen, Matthias

    2014-01-01

    Carbon monoxide (CO) is increasingly recognized as a cell-signalling molecule akin to nitric oxide (NO). CO has attracted particular attention as a potential therapeutic agent because of its reported anti-hypertensive, anti-inflammatory and cell-protective effects. We discuss recent progress in identifying new effector systems and elucidating the mechanisms of action of CO on, e.g., ion channels, as well as the design of novel methods to monitor CO in cellular environments. We also report on recent developments in the area of CO-releasing molecules (CORMs) and materials for controlled CO application. Novel triggers for CO release, metal carbonyls and degradation mechanisms of CORMs, are highlighted. In addition, potential formulations of CORMs for targeted CO release are discussed. PMID:24556640

  10. Controlled release mechanisms of spontaneously forming unilamellar vesicles.

    PubMed

    Nieh, Mu-Ping; Katsaras, John; Qi, Xiaoyang

    2008-06-01

    Spontaneously forming small unilamellar vesicles (SULVs) are easy to prepare and show great promise for use in delivering therapeutic payloads. We report of SULVs made up of the ternary phospholipid mixture, dimyristoyl-phosphatidylcholine (DMPC), dihexanoyl-phosphatidylcholine (DHPC) and dimyristoyl-phosphatidylglycerol (DMPG), which have been characterized by small angle neutron scattering (SANS). These low-polydispersity (0.14-0.19) SULVs range in size (i.e., radius) from 110 to 215 A and are capable of entrapping, and subsequently releasing, hydrophilic molecules (e.g., fluorescent dyes and quenchers) in a controlled fashion over two different temperature ranges. The low-temperature release mechanism involves the SULVs transforming into discoidal micelles, with an onset temperature (T(o)) of ~32 degrees C, while the high-temperature release mechanism is more gradual, presumably the result of defects formed through the continuous dissolution of DHPC into solution. Both of these mechanisms differ from other, previously reported thermosensitive liposomes. PMID:18394425

  11. Parental Behavioural Control and Academic Achievement: Striking the Balance between Control and Involvement

    ERIC Educational Resources Information Center

    Kramer, Karen Z.

    2012-01-01

    Using a longitudinal US dataset (N = 6,134) we examine the relationship between parental behavioural control and academic achievement and explore the moderating role of parental involvement and parental warmth. Analyses using multiple hierarchical regression with clustering controls shows that parental behavioural control is negatively associated…

  12. Optogenetic Control of Serotonin and Dopamine Release in Drosophila Larvae

    PubMed Central

    2014-01-01

    Optogenetic control of neurotransmitter release is an elegant method to investigate neurobiological mechanisms with millisecond precision and cell type-specific resolution. Channelrhodopsin-2 (ChR2) can be expressed in specific neurons, and blue light used to activate those neurons. Previously, in Drosophila, neurotransmitter release and uptake have been studied after continuous optical illumination. In this study, we investigated the effects of pulsed optical stimulation trains on serotonin or dopamine release in larval ventral nerve cords. In larvae with ChR2 expressed in serotonergic neurons, low-frequency stimulations produced a distinct, steady-state response while high-frequency patterns were peak shaped. Evoked serotonin release increased with increasing stimulation frequency and then plateaued. The steady-state response and the frequency dependence disappeared after administering the uptake inhibitor fluoxetine, indicating that uptake plays a significant role in regulating the extracellular serotonin concentration. Pulsed stimulations were also used to evoke dopamine release in flies expressing ChR2 in dopaminergic neurons and similar frequency dependence was observed. Release due to pulsed optical stimulations was modeled to determine the uptake kinetics. For serotonin, Vmax was 0.54 ± 0.07 μM/s and Km was 0.61 ± 0.04 μM; and for dopamine, Vmax was 0.12 ± 0.03 μM/s and Km was 0.45 ± 0.13 μM. The amount of serotonin released per stimulation pulse was 4.4 ± 1.0 nM, and the amount of dopamine was 1.6 ± 0.3 nM. Thus, pulsed optical stimulations can be used to mimic neuronal firing patterns and will allow Drosophila to be used as a model system for studying mechanisms underlying neurotransmission. PMID:24849718

  13. Controlled release niosome embedded chitosan system: effect of crosslink mesh dimensions on drug release.

    PubMed

    Williams, Eva Christabel; Toomey, Ryan; Alcantar, Norma

    2012-12-01

    We report on a model chemotherapy drug delivery system comprising nonionic surfactant vesicles (niosomes) packaged within a temperature-sensitive chitosan network. This smart packaging, or package-within-a package system, provides two distinct advantages. First, the gel prevents circulation of the niosomes and maintains delivery in the vicinity of a tumor. Second, the chitosan network protects the niosomes against fluctuations in tonicity, which affects delivery rates. Tonicity is the sum of the concentrations of the solutes which have the capacity to exert an osmotic force across the membrane. All release rate experiments were conducted with 5,6-carboxyfluorescein, a fluorescent dye. Release rates were monitored from both bare niosomes alone and niosome-embedded, chitosan networks. It was observed that chitosan networks prolonged delivery from 100 h to 55 days in low ionic strength environment and pH conditions similar to a tumor site. The primary effect of chitosan is to add control on release time and dosage, and stabilize the niosomes through a high ionic strength surrounding that prevents uncontrolled bursting of the niosomes. Secondary factors include crosslink density of the chitosan network, molecular weight of the individual chitosan polymers, dye concentration within the niosomes, and the number density of niosomes packaged within the chitosan network. Each of these factors can be altered to fine-tune release rates. PMID:22733611

  14. Role of various natural, synthetic and semi-synthetic polymers on drug release kinetics of losartan potassium oral controlled release tablets

    PubMed Central

    Jayasree, J.; Sivaneswari, S.; Hemalatha, G.; Preethi, N.; Mounika, B.; Murthy, S. Vasudeva

    2014-01-01

    Objective: The objective of the present work was to formulate and to characterize controlled release matrix tablets of losartan potassium in order to improve bioavailability and to minimize the frequency of administration and increase the patient compliance. Materials and Methods: Losartan potassium controlled release matrix tablets were prepared by direct compression technique by the use of different natural, synthetic and semisynthetic polymers such as gum copal, gum acacia, hydroxypropyl methyl cellulose K100 (HPMC K100), eudragit RL 100 and carboxy methyl ethyl cellulose (CMEC) individually and also in combination. Studies were carried out to study the influence of type of polymer on drug release rate. All the formulations were subjected to physiochemical characterization such as weight variation, hardness, thickness, friability, drug content, and swelling index. In vitro dissolution studies were carried out simulated gastric fluid (pH 1.2) for first 2 h and followed by simulated intestinal fluid (pH 6.8) up to 24 h, and obtained dissolution data were fitted to in vitro release kinetic equations in order to know the order of kinetics and mechanism of drug release. Results and Discussion: Results of physiochemical characterization of losartan potassium matrix tablets were within acceptable limits. Formulation containing HPMC K100 and CMEC achieved the desired drug release profile up to 24 h followed zero order kinetics, release pattern dominated by Korsmeyer — Peppas model and mechanism of drug release by nonfickian diffusion. The good correlation obtained from Hixson-Crowell model indicates that changes in surface area of the tablet also influences the drug release. Conclusion: Based on the results, losartan potassium controlled release matrix tablets prepared by employing HPMC K100 and CMEC can attain the desired drug release up to 24 h, which results in maintaining steady state concentration and improving bioavailability. PMID:25426439

  15. Cellulose, Chitosan, and Keratin Composite Materials. Controlled Drug Release

    PubMed Central

    2015-01-01

    A method was developed in which cellulose (CEL) and/or chitosan (CS) were added to keratin (KER) to enable [CEL/CS+KER] composites to have better mechanical strength and wider utilization. Butylmethylimmidazolium chloride ([BMIm+Cl–]), an ionic liquid, was used as the sole solvent, and because the [BMIm+Cl–] used was recovered, the method is green and recyclable. Fourier transform infrared spectroscopy results confirm that KER, CS, and CEL remain chemically intact in the composites. Tensile strength results expectedly show that adding CEL or CS into KER substantially increases the mechanical strength of the composites. We found that CEL, CS, and KER can encapsulate drugs such as ciprofloxacin (CPX) and then release the drug either as a single or as two- or three-component composites. Interestingly, release rates of CPX by CEL and CS either as a single or as [CEL+CS] composite are faster and independent of concentration of CS and CEL. Conversely, the release rate by KER is much slower, and when incorporated into CEL, CS, or CEL+CS, it substantially slows the rate as well. Furthermore, the reducing rate was found to correlate with the concentration of KER in the composites. KER, a protein, is known to have secondary structure, whereas CEL and CS exist only in random form. This makes KER structurally denser than CEL and CS; hence, KER releases the drug slower than CEL and CS. The results clearly indicate that drug release can be controlled and adjusted at any rate by judiciously selecting the concentration of KER in the composites. Furthermore, the fact that the [CEL+CS+KER] composite has combined properties of its components, namely, superior mechanical strength (CEL), hemostasis and bactericide (CS), and controlled drug release (KER), indicates that this novel composite can be used in ways which hitherto were not possible, e.g., as a high-performance bandage to treat chronic and ulcerous wounds. PMID:25548871

  16. Sustainable practices for fertilizer use through controlled release techniques

    NASA Astrophysics Data System (ADS)

    Faez, Roselena; Messa, Lucas; Froes, José; Souza, Claudinei

    2015-04-01

    Controlled release fertilizers are efficient tools that increase the sustainability of agricultural practices. However, the biodegradability of the matrices and the determination of the release into soil still require some investigation. This work describes the preparation of potassium-containing microspheres based on chitosan- montmorillonite clay as fertilizer double coated. The release profile in water (ion conductivity measurement) and soil (ion movement performed with time-domain reflectometry (TDR) technique) were evaluated. The potassium-containing microspheres were placed in a 7.5-L container filled with soil (Typic dystrophic LVd). The container was prepared with a water drainage system consisting of a thin layer of gravel at the bottom, which was followed by a geotextile fabric to prevent the loss of soil. The container was filled with soil (9 kg) in layers of 0.05 m to simulate the original bulk density of 1.30 g.cm-3. Each container received 4 g of microspheres placed at a single spot. They were placed at a depth of 10 cm. The fertilizer release was monitored using three electromagnetic probes for TDR that consisted of three continuous metal rods of 20 cm, which were in contact with the material and can be used to estimate the moisture and electrical conductivity. One probe was installed at the center of the container, which meant the rod was in contact with the microspheres in the soil. The other two probes were installed 5 cm from the central probe, and they were only in contact with the soil. Therefore, the purpose of these probes was to monitor the lateral displacement of the fertilizer from the microspheres in the soil. The release in water is fast than in soil, since the total amount of fertilizer in water was delivery during only one week and in soil during 60 days the fertilizer still continue drifting. The composite based on chitosan biopolymer as controlled release material is an efficient method to monitor the fertilizer consumption.

  17. Use of microcapsules as controlled release devices for coatings.

    PubMed

    Andersson Trojer, Markus; Nordstierna, Lars; Bergek, Jonatan; Blanck, Hans; Holmberg, Krister; Nydén, Magnus

    2015-08-01

    Biofouling of surfaces is a considerable problem in many industrial sectors and for the public community in general. The problem is usually approached by the use of functional coatings and most of such antifouling coatings rely on the effect of biocides. However, a substantial drawback is the poor control over the release of the biocide as well as its degradation in the paint. Encapsulation of the biocides in microcapsules is a promising approach that may overcome some of the problems associated with the more traditional ways of incorporating the antifouling agent into the formulation. In this review, we summarize more than a decade of microcapsule research from our lab as well as from other groups working on this topic. Focus will be on two coacervation-based encapsulation techniques; the internal phase separation method and the double emulsion method, which together enable the encapsulation of a broad spectrum of biocides with different physicochemical properties. The release of the biocide from core-shell particles and from encapsulated biocides in coatings is treated in detail. The release behaviour is interpreted in terms of the physicochemical properties of the core-shell particle and the coating matrix. In addition, special attention is given to the experimental release methodology and the implementation of proper diffusion models to describe the release. At the end of the review examples of antifouling properties of some coatings against common biofoulers are presented. PMID:25441449

  18. Formulation and Evaluation of Controlled Release Floating Microballoons of Stavudine

    PubMed Central

    Vidyadhara, Suryadevara; Sasidhar, Reddyvalam Lankapalli; Balakrishna, Talamanchi; Balaji, Boyapati; Amrutha, Ravi

    2015-01-01

    The aim of this study was to formulate and evaluate stavudine floating microballoons for controlled drug release. Initially, the drug-loaded low-density granular pellets were prepared with hydroxypropyl methylcellulose E5 grade and by using isopropyl alcohol as a granulating fluid. Further, the low-density granular pellets were subjected to microencapsulation by an emulsion evaporation technique using ethyl cellulose 7 cps and Eudragit S 100 as coating polymers and 1% w/v polyethylene glycol 400 as aqueous phase. The prepared microballoons were characterized for their particle size analysis, angle of repose, and compressibility index. The in vitro release studies were performed in 0.1 N HCl as medium. The prepared microballoons were free-flowing and spherical in shape. From all the formulations, F5E and F5F can be considered as promising controlled release floating microballoons of stavudine providing first-order release over a period of 12 hours, with a minimum floating lag time of 1 minute. It was found that the ratio of the drug & polymer, stirring speed, and concentration of surfactant were the most significant variables which influenced the size of the stavudine microballoons under the applied experimental conditions. PMID:26839847

  19. Formulation and Evaluation of Controlled Release Floating Microballoons of Stavudine.

    PubMed

    Vidyadhara, Suryadevara; Sasidhar, Reddyvalam Lankapalli; Balakrishna, Talamanchi; Balaji, Boyapati; Amrutha, Ravi

    2015-01-01

    The aim of this study was to formulate and evaluate stavudine floating microballoons for controlled drug release. Initially, the drug-loaded low-density granular pellets were prepared with hydroxypropyl methylcellulose E5 grade and by using isopropyl alcohol as a granulating fluid. Further, the low-density granular pellets were subjected to microencapsulation by an emulsion evaporation technique using ethyl cellulose 7 cps and Eudragit S 100 as coating polymers and 1% w/v polyethylene glycol 400 as aqueous phase. The prepared microballoons were characterized for their particle size analysis, angle of repose, and compressibility index. The in vitro release studies were performed in 0.1 N HCl as medium. The prepared microballoons were free-flowing and spherical in shape. From all the formulations, F5E and F5F can be considered as promising controlled release floating microballoons of stavudine providing first-order release over a period of 12 hours, with a minimum floating lag time of 1 minute. It was found that the ratio of the drug & polymer, stirring speed, and concentration of surfactant were the most significant variables which influenced the size of the stavudine microballoons under the applied experimental conditions. PMID:26839847

  20. pH-controlled drug release for dental applications

    NASA Astrophysics Data System (ADS)

    Wironen, John Francis

    A large proportion of the dental fillings replaced at present are revised because of the perceived presence of a recurrent caries under or adjacent to the restoration. Many of these perceived caries may not exist, while others may go undetected. This work describes the preparation of drug loaded polymer microspheres that sense the presence of the bacteria that cause caries by the associated presence of acid by-products of digestion. These microspheres are designed to swell and release their antimicrobial drugs once the pH drops to a level that would normally cause caries. The preparation of the microspheres as well as their loading with potassium fluoride, chlorhexidine digluconate, chlorhexidine dihydrochloride, chlorhexidine diacetate, and tetracycline hydrochloride are described. A detailed study of the controlled release behavior of fluoride as a function of polymer composition and pH is presented first. A study of the release kinetics of potassium fluoride, chlorhexidine digluconate, diacetate, dihydrochloride, and tetracycline hydrochloride as a function of pH in the same polymer system is then presented. Additional studies of the swelling kinetics of chlorhexidine-loaded microspheres in various pH buffers are discussed with special reference to correlations with the controlled-release data. Finally, an experiment in which the microspheres are tested in an in vitro bacteria model that includes Streptococcus mutans is presented and discussed in detail.

  1. Nanoscale architectural tuning of parylene patch devices to control therapeutic release rates

    NASA Astrophysics Data System (ADS)

    Pierstorff, Erik; Lam, Robert; Ho, Dean

    2008-11-01

    The advent of therapeutic functionalized implant coatings has significantly impacted the medical device field by enabling prolonged device functionality for enhanced patient treatment. Incorporation of drug release from a stable, biocompatible surface is instrumental in decreasing systemic application of toxic therapeutics and increasing the lifespan of implants by the incorporation of antibiotics and anti-inflammatories. In this study, we have developed a parylene C-based device for controlled release of Doxorubicin, an anti-cancer chemotherapy and definitive read-out for preserved drug functionality, and further characterized the parylene deposition condition-dependent tunability of drug release. Drug release is controlled by the deposition of a layer of 20-200 nm thick parylene over the drug layer. This places a porous layer above the Doxorubicin, limiting drug elution based on drug accessibility to solvent and the solvent used. An increase in the thickness of the porous top layer prolongs the elution of active drug from the device from, in the conditions tested, the order of 10 min to the order of 2 d in water and from the order of 10 min to no elution in PBS. Thus, the controlled release of an anti-cancer therapeutic has been achieved via scalably fabricated, parylene C-encapsulated drug delivery devices.

  2. Encapsulation-free controlled release: Electrostatic adsorption eliminates the need for protein encapsulation in PLGA nanoparticles

    PubMed Central

    Pakulska, Malgosia M.; Elliott Donaghue, Irja; Obermeyer, Jaclyn M.; Tuladhar, Anup; McLaughlin, Christopher K.; Shendruk, Tyler N.; Shoichet, Molly S.

    2016-01-01

    Encapsulation of therapeutic molecules within polymer particles is a well-established method for achieving controlled release, yet challenges such as low loading, poor encapsulation efficiency, and loss of protein activity limit clinical translation. Despite this, the paradigm for the use of polymer particles in drug delivery has remained essentially unchanged for several decades. By taking advantage of the adsorption of protein therapeutics to poly(lactic-co-glycolic acid) (PLGA) nanoparticles, we demonstrate controlled release without encapsulation. In fact, we obtain identical, burst-free, extended-release profiles for three different protein therapeutics with and without encapsulation in PLGA nanoparticles embedded within a hydrogel. Using both positively and negatively charged proteins, we show that short-range electrostatic interactions between the proteins and the PLGA nanoparticles are the underlying mechanism for controlled release. Moreover, we demonstrate tunable release by modifying nanoparticle concentration, nanoparticle size, or environmental pH. These new insights obviate the need for encapsulation and offer promising, translatable strategies for a more effective delivery of therapeutic biomolecules. PMID:27386554

  3. Magnetocubosomes for the delivery and controlled release of therapeutics.

    PubMed

    Montis, Costanza; Castroflorio, Benedetta; Mendozza, Marco; Salvatore, Annalisa; Berti, Debora; Baglioni, Piero

    2015-07-01

    The design of nanostructured drug delivery systems (DDS) that improve the efficacy of therapeutic principles by enhancing their biocompatibility, bioavailability and targeting, has been the focus of extensive research over the past years. Of particular relevance in this field is the development of multifunctional architectures that can deliver different therapeutics or diagnostic agents and release them in a controlled way. In this study we report on the design, preparation and characterization of a DDS where hydrophobic Fe3O4 magnetic nanoparticles (NPs) are included in the bilayer of bicontinuous cubic lipid nanoparticles of Glyceryl Monooleate (GMO). The "magnetocubosomes" are characterized and investigated in terms of their ability to encapsulate and release both hydrophilic and hydrophobic model drugs. For the first time Fluorescence Correlation Spectroscopy (FCS) is used to study the diffusion of encapsulated molecules inside the bicontinuous cubic phase and to monitor their release from the matrix towards the aqueous phase. In addition, we show with the same technique that magnetocubosomes are responsive to a low frequency alternating magnetic field (LF-AMF), which acts as an external trigger to boost the release of model drugs confined in the cubic phase. Magnetocubosomes, reported for the first time in this paper, represent a novel biocompatible, multifunctional and responsive DDS. PMID:25533536

  4. Controlled release drug delivery systems to improve post-operative pharmacotherapy.

    PubMed

    Bhusal, Prabhat; Harrison, Jeff; Sharma, Manisha; Jones, David S; Hill, Andrew G; Svirskis, Darren

    2016-10-01

    Over 230 million surgical procedures are conducted worldwide each year with numbers increasing. Pain, undesirable inflammation and infection are common complications experienced by patients following surgery. Opioids, non-steroidal anti-inflammatory drugs (NSAIDs), local anaesthetics (LAs) and antibiotics are the commonly administered drugs peri-operatively to manage these complications. Post-operative pharmacotherapy is typically achieved using immediate-release dosage forms of drugs, which lead to issues around fluctuating plasma concentrations, systemic adverse effects and poor patient adherence. Controlled release (CR) systems for certain medicines including opioids, NSAIDs and antibiotics have demonstrably enhanced treatment efficacy in the post-surgical setting. However, challenges remain to ensure patient safety while achieving individual therapeutic needs. Newer CR systems in the research and development pipeline have a high level of control over medicine release, which can be initiated, tuned or stopped on-demand. Future systems will self-regulate drug release in response to biological markers providing precise individualized therapy. In this review, we cover currently adopted CR systems in post-operative pharmacotherapy, including drug eluting medical devices, and highlight a series of examples of novel CR technologies that have the potential for translation into post-surgical settings to improve medication efficacy and enhance post-surgical recovery. PMID:27329201

  5. Photoremovable protecting groups as controlled-release device for sex pheromone.

    PubMed

    Atta, Sanghamitra; Ikbal, Mohammed; Boda, Nishitha; Gauri, Samiran S; Singh, N D Pradeep

    2013-02-01

    Photoremovable protecting groups (PRPGs) were demonstrated as a delivery device for controlled release of pheromone under both UV light (≥350 nm) and direct sunlight irradiation. In the present work, (Z)-11-hexadecen-1-ol (sex pheromone of Chilo infuscatellus Snellen) was chemically caged by four different photoremovable protecting groups (7-hydroxy-4-hydroxymethylcoumarin, 1-pyrenemethanol, 9-anthracenemethanol and 2-(hydroxymethyl)anthraquinone) individually. Photophysical studies showed that the caged pheromone with coumarin, pyrene and anthracene derivatives exhibited strong fluorescence. Controlled release of (Z)-11-hexadecen-1-ol was achieved by irradiating the caged compounds in aqueous ethanol both under UV and sunlight. Further, to mimic the environmental conditions, controlled release of (Z)-11-hexadecen-1-ol was also studied in soil medium under direct sunlight. Thermogravimetric analysis showed that caging of (Z)-11-hexadecen-1-ol by PRPGs significantly reduced its volatility. Bioassay experiments indicated that PRPGs are harmless to soil bacteria (Azotobacter sp. and Pseudomonas aeruginosa) and in vitro cytotoxicity studies on eukaryotic L929 cells showed that PRPGs are also non-toxic. Field bioassays were performed using caged pheromone against maize stalk borer (Chilo partellus) and the results showed that the caged alcohol is effective in a number of moths catches instead of free alcohol in a blend for a longer period of time. Our studies indicated that use of PRPGs as delivery device for controlled release of pheromone by sunlight holds great interest for field applications. PMID:23108352

  6. Vaccine adjuvants - Current status and prospects on controlled release adjuvancity.

    PubMed

    Sivakumar, S M; Safhi, Mohammed M; Kannadasan, M; Sukumaran, N

    2011-10-01

    The strategy of World Health Organization is to develop efficient and inexpensive vaccine against various infectious diseases amongst children's population. Vaccination is considered as the most cost effective health intervention known to public. Since 90 years various substances have been added in vaccine formulation but still alum is considered as the safest adjuvant for human use licensed by United States Food and Drug Administration. MF 59 and ASO4 are the adjuvants were developed recently and approved for human use. Due to poor adjuvancity, conventional vaccines require multiple recall injection at approximately time intervals to attain optimal immune response. For past approximately two decades the vaccine research has been focused towards the alternation of alum type of adjuvant in order to increase the immunogenicity. The development of new vaccines, is more efficacious or easier to deliver, or both have become an area of research that can certainly benefit from controlled release technology. Especially, the conversion of multiple administration vaccine into single administration vaccine may represent an improved advancement towards the betterment of human health care and welfare. Biodegradable polymer microparticles have been evaluated for delivering antigens in native form, sustained release keeping in mind the safety aspects. In this article we review the overall concept of adjuvants in vaccine technology with special focus towards the prospects of controlled release antigens. PMID:23960760

  7. In vitro controlled release of colon targeted mesalamine from compritol ATO 888 based matrix tablets using factorial design

    PubMed Central

    Patel, J.K.; Patel, N.V.; Shah, S.H.

    2009-01-01

    A controlled release matrix formulation for mesalamine was designed and developed to achieve a 24 h release profile. Using compritol 888 ATO (glyceryl behenate) as an inert matrix-forming agent to control the release of mesalamine, formulation granules containing the solid dispersions were investigated. Pectin, a polysaccharide, was used as bacterial dependent polymer for colon targeting. The matrix tablets for these formulations were prepared by direct compression and their in vitro release tests were carried out. A 32 full factorial design was used for optimization by taking the amounts of glyceryl behenate (X1) and pectin (X2) as independent variables and percentage drug released at 2 (Q2), 16 (Q16) and 24 (Q24) h as dependent variables. Drug release from the matrix tablets formulations lasted for over 24 h. Images of the tablet surface and cross-section were characterized by scanning electron microscopy to show the formed pores and channels in the matrices. These may provide the release pathway for the inner embedded drugs. The co-mixing of polysaccharide pectin, into the waxy matrices played a meaningful role in targeting the tablets to colon. The drug release from the novel formulation may be attributed to the diffusion-controlled mechanism. The results of the full factorial design indicated that an optimum amount of compritol ATO 888 and a high amount of pectin favors the colon targeting and controlled release of mesalamine from dosage form. PMID:21589801

  8. Controlling the release of peptide antimicrobial agents from surfaces.

    PubMed

    Shukla, Anita; Fleming, Kathleen E; Chuang, Helen F; Chau, Tanguy M; Loose, Christopher R; Stephanopoulos, Gregory N; Hammond, Paula T

    2010-03-01

    Medical conditions are often exacerbated by the onset of infection caused by hospital dwelling bacteria such as Staphylococcus aureus. Antibiotics taken orally or intravenously can require large and frequent doses, further contributing to the sharp rise in resistant bacteria observed over the past several decades. These existing antibiotics are also often ineffective in preventing biofilm formation, a common cause of medical device failure. Local delivery of new therapeutic agents that do not allow bacterial resistance to occur, such as antimicrobial peptides, could alleviate many of the problems associated with current antibacterial treatments. By taking advantage of the versatility of layer-by-layer assembly of polymer thin films, ponericin G1, an antimicrobial peptide known to be highly active against S. aureus, was incorporated into a hydrolytically degradable polyelectrolyte multilayer film. Several film architectures were examined to obtain various drug loadings that ranged from 20 to 150 microg/cm2. Release was observed over approximately ten days, with varying release profiles, including burst as well as linear release. Results indicated that film-released peptide did not suffer any loss in activity against S. aureus and was able to inhibit bacteria attachment, a necessary step in preventing biofilm formation. Additionally, all films were found to be biocompatible with the relevant wound healing cells, NIH 3T3 fibroblasts and human umbilical vein endothelial cells. These films provide the level of control over drug loading and release kinetics required in medically relevant applications including coatings for implant materials and bandages, while eliminating susceptibility to bacterial resistance. PMID:20004967

  9. Temporally controlled release of multiple growth factors from a self-assembling peptide hydrogel.

    PubMed

    Bruggeman, Kiara F; Rodriguez, Alexandra L; Parish, Clare L; Williams, Richard J; Nisbet, David R

    2016-09-23

    Protein growth factors have demonstrated great potential for tissue repair, but their inherent instability and large size prevents meaningful presentation to biologically protected nervous tissue. Here, we create a nanofibrous network from a self-assembling peptide (SAP) hydrogel to carry and stabilize the growth factors. We significantly reduced growth factor degradation to increase their lifespan by over 40 times. To control the temporal release profile we covalently attached polysaccharide chitosan molecules to the growth factor to increase its interactions with the hydrogel nanofibers and achieved a 4 h delay, demonstrating the potential of this method to provide temporally controlled growth factor delivery. We also describe release rate based analysis to examine the growth factor delivery in more detail than standard cumulative release profiles allow and show that the chitosan attachment method provided a more consistent release profile with a 60% reduction in fluctuations. To prove the potential of this system as a complex growth factor delivery platform we demonstrate for the first time temporally distinct release of multiple growth factors from a single tissue specific SAP hydrogel: a significant goal in regenerative medicine. PMID:27517970

  10. Temporally controlled release of multiple growth factors from a self-assembling peptide hydrogel

    NASA Astrophysics Data System (ADS)

    Bruggeman, Kiara F.; Rodriguez, Alexandra L.; Parish, Clare L.; Williams, Richard J.; Nisbet, David R.

    2016-09-01

    Protein growth factors have demonstrated great potential for tissue repair, but their inherent instability and large size prevents meaningful presentation to biologically protected nervous tissue. Here, we create a nanofibrous network from a self-assembling peptide (SAP) hydrogel to carry and stabilize the growth factors. We significantly reduced growth factor degradation to increase their lifespan by over 40 times. To control the temporal release profile we covalently attached polysaccharide chitosan molecules to the growth factor to increase its interactions with the hydrogel nanofibers and achieved a 4 h delay, demonstrating the potential of this method to provide temporally controlled growth factor delivery. We also describe release rate based analysis to examine the growth factor delivery in more detail than standard cumulative release profiles allow and show that the chitosan attachment method provided a more consistent release profile with a 60% reduction in fluctuations. To prove the potential of this system as a complex growth factor delivery platform we demonstrate for the first time temporally distinct release of multiple growth factors from a single tissue specific SAP hydrogel: a significant goal in regenerative medicine.

  11. Novel Thermogelling Dispersions of Polymer Nanoparticles for Controlled Protein Release

    PubMed Central

    Cai, Tong; Hu, Peter D.; Sun, Manwu; Zhou, Jun; Tsai, Yi-Ting; Baker, David; Tang, Liping

    2012-01-01

    A novel poly(oligo(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) ethyl ether methacrylate)/ poly(acrylic acid) interpenetrating network (IPN) nanoparticle was synthesized. The temperature-responsive properties of the IPN nanoparticles were investigated by dynamic light scattering method. Atomic force microscopic images confirm the homogenous and mono-disperse morphology of the IPN nanoparticles. Both visual observation and viscosity testing demonstrated that the IPN nanoparticles exhibit thermogelling properties at body temperature, 37°C. Subsequent studies verified that such temperature sensitive properties of IPN nanoparticles allow their ease of injection and then slow release of model proteins, both in vitro and in vivo. Histological analysis showed that our IPN implants exerted minimal inflammation following subcutaneous implantation. Our results support that, by simply mixing with proteins of interest, the novel IPN nanoparticles can be used to form in situ thermogelling devices for controlled protein release. PMID:22349097

  12. Thermoresponsive double network micropillared hydrogels for controlled cell release.

    PubMed

    Fei, Ruochong; Hou, Huijie; Munoz-Pinto, Dany; Han, Arum; Hahn, Mariah S; Grunlan, Melissa A

    2014-09-01

    Thermoresponsive poly(N-isopropylacrylamide) hydrogels (PNIPAAm) have been widely used for controlled cell detachment. In this study, cell release is enhanced via deswelling with a two-pronged approach combining a double network (DN) design and micropatterning. PNIPAAm hydrogels are prepared as DNs comprised of a tightly crosslinked 1st network and a loosely crosslinked 2nd network. Moreover, the PNIPAAm DN hydrogels are prepared as both planar 1.5 mm-thick slabs as well as micropillar arrays (≈200 μm pillar diameter). Compared to the corresponding conventional single network (SN) hydrogels, DN hydrogels exhibit enhanced thermosensitivity and cell release efficiency, particularly for the micropillar arrays. PMID:24956117

  13. Chitosan hydrogels for chondroitin sulphate controlled release: an analytical characterization.

    PubMed

    Bianchera, Annalisa; Salomi, Enrico; Pezzanera, Matteo; Ruwet, Elisabeth; Bettini, Ruggero; Elviri, Lisa

    2014-01-01

    This paper provides an analytical characterization of chitosan scaffolds obtained by freeze-gelation toward the uptake and the controlled release of chondroitin sulphate (CS), as cartilage repair agent, under different pH conditions. Scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and liquid chromatography-UV spectrophotometry (LC-UV) techniques were exploited to obtain qualitative and quantitative descriptions of polymer and drug behaviour in the biomaterial. As for morphology, SEM analysis allowed the evaluation of scaffold porosity in terms of pore size and distribution both at the surface (Feret diameter 58 ± 19 μm) and on the cross section (Feret diameter 106 ± 51 μm). LC and ATR-FTIR evidenced a pH-dependent CS loading and release behaviour, strongly highlighting the role of electrostatic forces on chitosan/chondroitin sulphate interactions. PMID:25614850

  14. Chitosan Hydrogels for Chondroitin Sulphate Controlled Release: An Analytical Characterization

    PubMed Central

    Bianchera, Annalisa; Salomi, Enrico; Pezzanera, Matteo; Ruwet, Elisabeth; Bettini, Ruggero; Elviri, Lisa

    2014-01-01

    This paper provides an analytical characterization of chitosan scaffolds obtained by freeze-gelation toward the uptake and the controlled release of chondroitin sulphate (CS), as cartilage repair agent, under different pH conditions. Scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and liquid chromatography-UV spectrophotometry (LC-UV) techniques were exploited to obtain qualitative and quantitative descriptions of polymer and drug behaviour in the biomaterial. As for morphology, SEM analysis allowed the evaluation of scaffold porosity in terms of pore size and distribution both at the surface (Feret diameter 58 ± 19 μm) and on the cross section (Feret diameter 106 ± 51 μm). LC and ATR-FTIR evidenced a pH-dependent CS loading and release behaviour, strongly highlighting the role of electrostatic forces on chitosan/chondroitin sulphate interactions. PMID:25614850

  15. Optical control of insulin release using a photoswitchable sulfonylurea

    PubMed Central

    Broichhagen, Johannes; Schönberger, Matthias; Cork, Simon C.; Frank, James A.; Marchetti, Piero; Bugliani, Marco; Shapiro, A. M. James; Trapp, Stefan; Rutter, Guy A.; Hodson, David J.; Trauner, Dirk

    2014-01-01

    Sulfonylureas are widely prescribed for the treatment of type 2 diabetes mellitus (T2DM). Through their actions on ATP-sensitive potassium (KATP) channels, sulfonylureas boost insulin release from the pancreatic beta cell mass to restore glucose homeostasis. A limitation of these compounds is the elevated risk of developing hypoglycemia and cardiovascular disease, both potentially fatal complications. Here, we describe the design and development of a photoswitchable sulfonylurea, JB253, which reversibly and repeatedly blocks KATP channel activity following exposure to violet-blue light. Using in situ imaging and hormone assays, we further show that JB253 bestows light sensitivity upon rodent and human pancreatic beta cell function. Thus, JB253 enables the optical control of insulin release and may offer a valuable research tool for the interrogation of KATP channel function in health and T2DM. PMID:25311795

  16. Controlled release of ibuprofen by meso–macroporous silica

    SciTech Connect

    Santamaría, E. Maestro, A.; Porras, M.; Gutiérrez, J.M.; González, C.

    2014-02-15

    Structured meso–macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (EO{sub 19}PO{sub 39}EO{sub 19}) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption–desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso–macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system. - Graphical abstract: Ibuprofen release profiles for the materials obtained from samples P84{sub m}eso (black diamonds), P84{sub 2}0% (white squares), P84{sub 5

  17. Graphene as a photothermal switch for controlled drug release

    NASA Astrophysics Data System (ADS)

    Matteini, Paolo; Tatini, Francesca; Cavigli, Lucia; Ottaviano, Stefania; Ghini, Giacomo; Pini, Roberto

    2014-06-01

    Graphene has recently emerged as a novel material in the biomedical field owing to its optical properties, biocompatibility, large specific surface area and low cost. In this paper, we provide the first demonstration of the possibility of using light to remotely trigger the release of drugs from graphene in a highly controlled manner. Different drugs including chemotherapeutics and proteins are firmly adsorbed onto reduced graphene oxide (rGO) nanosheets dispersed in a biopolymer film and then released by individual millisecond-long light pulses generated by a near infrared (NIR) laser. Here graphene plays the dual role of a versatile substrate for temporary storage of drugs and an effective transducer of NIR-light into heat. Drug release appears to be narrowly confined within the size of the laser spot under noninvasive conditions and can be precisely dosed depending on the number of pulses. The approach proposed paves the way for tailor-made pharmacological treatments of chronic diseases, including cancer, anaemia and diabetes.Graphene has recently emerged as a novel material in the biomedical field owing to its optical properties, biocompatibility, large specific surface area and low cost. In this paper, we provide the first demonstration of the possibility of using light to remotely trigger the release of drugs from graphene in a highly controlled manner. Different drugs including chemotherapeutics and proteins are firmly adsorbed onto reduced graphene oxide (rGO) nanosheets dispersed in a biopolymer film and then released by individual millisecond-long light pulses generated by a near infrared (NIR) laser. Here graphene plays the dual role of a versatile substrate for temporary storage of drugs and an effective transducer of NIR-light into heat. Drug release appears to be narrowly confined within the size of the laser spot under noninvasive conditions and can be precisely dosed depending on the number of pulses. The approach proposed paves the way for tailor

  18. Malaria in Turkey: successful control and strategies for achieving elimination.

    PubMed

    Özbilgina, Ahmet; Topluoglu, Seher; Es, Saffet; Islek, Elif; Mollahaliloglu, Salih; Erkoc, Yasin

    2011-01-01

    Turkey is located in the middle of Asia, Africa and Europe, close to Caucasia, Balkans and Middle East in subtropical climate zone. Malaria has been known since the early ages of human history and it was one of the leading diseases in Anatolian history, as well. Today, chloroquine-sensitive Plasmodium vivax is the only agent of autochthonous malaria cases in Turkey. The other Plasmodium species identified are isolated from imported cases of malaria. The most common vector of malaria in Turkey is Anopheles sacharovi followed by An. superpictus, An. maculipennis and An. subalpinus. In 2009, pre-elimination stage of Malaria Program was started due to dramatic decline in the number of malaria cases in Turkey (Total, 84; 38 autochthonous cases only in 26 foci in south-eastern Anatolia, and 46 imported cases; incidence: 0.1/100,000). As there were no detected cases of new autochthonous malaria in the first 8 months of 2010, elimination stage was started. The role of the persistent policies and successful applications of the Ministry of Health, such as the strict control of the patients using anti-malarial drugs especially chloroquine, avoidance of resistant insecticides, facilitation of access to patients via Health Transformation Program (HTP), establishment of close contact with the patients' families, and improvement of reporting and surveillance system, was essential. In addition, improvement maintained in the motivations and professional rights of malaria workers, as well in the coordination of field studies and maintenance of a decline or termination in vector-to-person transmission were all achieved with the insistent policies of the Ministry of Health. Other factors that probably contributed to elimination studies include lessening of military operations in south-eastern Anatolia and the lowering of malaria cases in neighbouring countries in recent years. Free access to health services concerning malaria is still successfully conducted throughout the country

  19. Leveraging electrokinetics for the active control of dendritic fullerene-1 release across a nanochannel membrane

    NASA Astrophysics Data System (ADS)

    Bruno, Giacomo; Geninatti, Thomas; Hood, R. Lyle; Fine, Daniel; Scorrano, Giovanni; Schmulen, Jeffrey; Hosali, Sharath; Ferrari, Mauro; Grattoni, Alessandro

    2015-03-01

    General adoption of advanced treatment protocols such as chronotherapy will hinge on progress in drug delivery technologies that provide precise temporal control of therapeutic release. Such innovation is also crucial to future medicine approaches such as telemedicine. Here we present a nanofluidic membrane technology capable of achieving active and tunable control of molecular transport through nanofluidic channels. Control was achieved through application of an electric field between two platinum electrodes positioned on either surface of a 5.7 nm nanochannel membrane designed for zero-order drug delivery. Two electrode configurations were tested: laser-cut foils and electron beam deposited thin-films, configurations capable of operating at low voltage (<=1.5 V), and power (100 nW). Temporal, reproducible tuning and interruption of dendritic fullerene 1 (DF-1) transport was demonstrated over multi-day release experiments. Conductance tests showed limiting currents in the low applied potential range, implying ionic concentration polarization (ICP) at the interface between the membrane's micro- and nanochannels, even in concentrated solutions (<=1 M NaCl). The ability of this nanotechnology platform to facilitate controlled delivery of molecules and particles has broad applicability to next-generation therapeutics for numerous pathologies, including autoimmune diseases, circadian dysfunction, pain, and stress, among others.General adoption of advanced treatment protocols such as chronotherapy will hinge on progress in drug delivery technologies that provide precise temporal control of therapeutic release. Such innovation is also crucial to future medicine approaches such as telemedicine. Here we present a nanofluidic membrane technology capable of achieving active and tunable control of molecular transport through nanofluidic channels. Control was achieved through application of an electric field between two platinum electrodes positioned on either surface of a 5

  20. Controlled release matrix tablets of glipizide: Influence of different grades of ethocel and Co-excipient on drug release.

    PubMed

    Mehsud, Saif Ullah; Khan, Gul Majid; Hussain, Abid; Akram, Muhammad; Akhlaq, Muhammad; Khan, Kamran Ahmad; Shakoor, Abdul

    2016-05-01

    The aim of the current study was to formulate and evaluate glipizide controlled release matrix tablets by means of different grades of polymer Ethoceland different co-excipients in order to evaluate their effect on drug release profiles during in vitro dissolution studies. Type II diabetes mellitus is usually treated with Glipizide. Glipizide belongs to sulfonylurea group. Gastric disturbance and severe hypoglycemia has been observed after taking glipizide orally. To overcome these problems, controlled release matrices were developed using different grades of ethyl cellulose polymer with a drug-polymer ratio of 1:3by the direct compression method. The effect on drug release of partial replacement of lactose by different co-excipients, HPMC K100M, starch and CMC, were also studied. Diameter, thickness, hardness, friability, weight variations, drug contents of formulations were tested, these properties were within prescribed limits. Co-excipients and polymer containing formulations were compared to the without co-excipients and polymer containing formulations with respect to their release profile. After a 24-hour release study, ethyl cellulose polymer containing formulation exhibited prolonged release for 5-16 hours; however the polymer Ethocel (R) standard FP 7 Premium without co-excipient containing formulation exhibited controlled release for 24 hours. Incompatibility was investigated between drugs, co-excipient DSC and polymer study was performed and any type of interaction was not found. Different kinetic models were used to study the release mechanism. An enhanced release rate was observed in case of excipients containing formulations. PMID:27166548

  1. Controlled release of photoswitch drugs by degradable polymer microspheres

    PubMed Central

    Groynom, Rebecca; Shoffstall, Erin; Wu, Larry S.; Kramer, Richard H.; Lavik, Erin B.

    2016-01-01

    Background QAQ and DENAQ are synthetic photoswitch compounds that change conformation in response to light, altering current flow through voltage-gated ion channels in neurons. These compounds are drug candidates for restoring light sensitivity in degenerative blinding diseases such as AMD. Purpose However, these photoswitch compounds are cleared from the eye within several days, they must be administered through repeated intravitreal injections. Therefore, we are investigating local, sustained delivery formulations to constantly replenish these molecules and have the potential to restore sight. Methods Here, we encapsulate QAQ and DENAQ into several molecular weights of PLGA through an emulsion technique to assess the viability of delivering the compounds in their therapeutic window over many weeks. We characterize the loading efficiency, release profile, and bioactivity of the compounds after encapsulation. Results A very small burst release was observed for all of the formulations with the majority being delivered over the following two months. The lowest molecular weight PLGA led to the highest loading and most linear delivery for both QAQ and DENAQ. Bioactivity was retained for both compounds across the polymers. Conclusion These results present encapsulation into polymers by emulsion as a viable option for controlled release of QAQ and DENAQ. PMID:26453166

  2. Genipin-modified gelatin nanocarriers as swelling controlled drug delivery system for in vitro release of cytarabine.

    PubMed

    Khan, Huda; Shukla, R N; Bajpai, A K

    2016-04-01

    The aim of the present investigation was to design biocompatible gelatin nanoparticles, capable of releasing the cytarabine drug in a controllable way by regulating the extent of swelling of nanoparticles. In order to achieve the proposed objectives, gelatin (Type A, derived from acid cured tissue) was modified by crosslinking with genipin and nanoparticles of crosslinked gelatin were prepared using single water in oil (W/O) emulsion technique. The nanoparticles were characterized by techniques like FTIR, SEM, TEM, particles size analysis, and surface potential measurements. The nanoparticle chemical architecture was found to influence drug-releasing capacity. The influence of experimental conditions such as pH and simulated physiological fluids as the release medium was also investigated on the release profiles of cytarabine. It is possible to fabricate high-performance materials, by designing of controlled size gelatin nanoparticles with good biocompatible properties along with desired drug release profiles. PMID:26838872

  3. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    NASA Astrophysics Data System (ADS)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J.

    2011-02-01

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s - 1. Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  4. Protease degradable tethers for controlled and cell-mediated release of nanoparticles in 2- and 3-dimensions

    PubMed Central

    Tokatlian, Talar; Shrum, Chadwick T.; Kadoya, Warren M.; Segura, Tatiana

    2010-01-01

    Strategies to control the release rate of bioactive signals from tissue engineering scaffolds are essential for tissue regeneration and tissue engineering applications. Here we report on a strategy to achieve temporal control over nanoparticle release from biomaterials using cell-secreted proteases. This cell-triggered release approach utilizes peptides that are degraded by matrix metalloproteinases (MMPs) at different rates to immobilize nanoparticles directly to the biomaterial surface. Thus, the peptide-immobilized nanoparticles are released with temporal control through the action of cell-released MMPs. We found that release rates of peptide-immobilized nanoparticles were a function of peptide sensitivity to proteases, the number of tethers between the nanoparticle and the surface and the concentration of proteases used to induce release. Cellular internalization of the peptide-immobilized nanoparticles was also a function of the peptide sensitivity to proteases, the number of tethers between the nanoparticle and the surface and MMP expression profile of the cells. Similar trends were observed for peptide-immobilized nanoparticles inside micro-porous hydrogels, indicating protease sensitive tethers are effective in controlling release rate and internalization of nanoparticles. Such a temporal delivery strategy of nanoparticles loaded with therapeutic payloads (e.g. protein, DNA, siRNA) can be an ideal means to guide tissue formation. PMID:20688389

  5. Formulation and evaluation of olanzapine matrix pellets for controlled release

    PubMed Central

    Vishal Gupta, N.; Balamuralidhara, V.; Mohammed Khan, S.

    2011-01-01

    Background and the purpose of the study Olanzapine is an antipsychotic used in treatment of schizophrenia. This research was carried out to design oral controlled release matrix pellets of water insoluble drug Olanzapine (OZ), using blend of Sodium Alginate (SA) and Glyceryl Palmito-Stearate (GPS) as matrix polymers, micro crystalline cellulose (MCC) as spheronizer enhancer and Sodium Lauryl Sulphate (SLS) as pore forming agent. Methods OZ formulations were developed by the pelletization technique by drug loaded pellets and characterized with regard to the drug content, size distribution, Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction study (XRD). Stability studies were carried out on the optimized formulation for a period of 90 days at 40±2 °C and 75±5% relative humidity. Results and major conclusion The drug content was in the range of 93.34–98.12%. The mean particle size of the drug loaded pellets was in the range 1024 to 1087µm. SEM photographs and calculated sphericity factor confirmed that the prepared formulations were spherical in nature. The compatibility between drug and polymers in the drug loaded pellets was confirmed by DSC and FTIR studies. Stability studies indicated that pellets are stable. XRD patterns revealed the crystalline nature of the pure OZ. Loose surface crystal study indicated that crystalline OZ is present in all formulations and more clear in formulation F5. Drug release was controlled for more than 24 hrs and mechanism of the drug release followed by Fickian diffusion. It may be concluded that F5 is an ideal formulation for once a day administration. PMID:22615665

  6. An oral controlled release system for ambroxol hydrochloride containing a wax and a water insoluble polymer.

    PubMed

    Chi, Na; Guo, Ju Hong; Zhang, Yu; Zhang, Wei; Tang, Xing

    2010-01-01

    This study was carried out to develop and optimize oral sustained-release formulations for Ambroxol hydrochloride matrix pellets using a combination of wax and water-insoluble polymer, glyceryl behenate (Compritol 888 ATO) and Ethylcellulose (EC(7 FP)). It involved three factors: the content of Compritol 888 ATO (X(1)), EC(7 FP) (X(2)), and the matrix formation methods (X(3)), as independent variables. The drug release percentages at 1, 2 and 4 h were the target responses and were restricted to 15-45% (Y(1)), 45-80% (Y(2)) and 80-100% (Y(3)), respectively. The final blend formulation prepared by extrusion spheronization, was achieved with 27.00% (w/w) Ambroxol hydrochloride, 48.70% (w/w) Compritol 888 ATO, and 24.30% (w/w) EC(7 Fp) with 40 degrees C for 12 h. Comparing the single matrix materials consisting of just the wax or water-insoluble in the complex matrix system containing wax and water-insoluble polymer, the release of the drug can be far more retarded, when the formulations have undergone the process of heat treatment. Furthermore, the combination of the two polymers, with flexible matrix formation methods, will offer a very promising way of producing matrix pellets instead of coated controlled-release pellets to meet various demands of drug release. PMID:19671037

  7. Formulation and drying of alginate beads for controlled release and stabilization of invertase.

    PubMed

    Santagapita, Patricio R; Mazzobre, M Florencia; Buera, M Pilar

    2011-09-12

    Several alternatives to the conventional alginate beads formulation were studied for encapsulation of invertase. Pectin was added to the alginate/enzyme solution while trehalose and β-cyclodextrin were added to the calcium gelation media. The effect of composition changes, freezing, drying methods (freeze, vacuum, or air drying), and thermal treatment were evaluated on invertase stability and its release kinetics from beads. The enzyme release mechanism from wet beads depended on pH. The addition of trehalose, pectin, and β-cyclodextrin modified the bead structure, leading in some cases to a release mechanism that included the relaxation of the polymer chains, besides Fickian diffusion. Enzyme release from vacuum-dried beads was much faster than from freeze-dried beads, probably due to their higher pore size. The inclusion of β-cyclodextrin and especially of pectin prevented enzyme activity losses during bead generation, and trehalose addition was fundamental for achieving adequate invertase protection during freezing, drying, and thermal treatment. Present results showed that several alternatives such as drying method, composition, as well as pH of the relese medium can be managed to control enzyme release. PMID:21809830

  8. Physical and chemical control of released microorganisms at field sites

    SciTech Connect

    Donegan, K.; Seidler, R.; Matyac, C.

    1991-01-01

    An important consideration in the environmental release of a genetically engineered microorganism (GEM) is the capability for reduction or elimination of GEM populations once their function is completed or if adverse environmental effects are observed. The decontamination treatments of burning and biocide application, alone and in combination with tilling, were evaluated for their ability to reduce populations of bacteria released on the phylloplane. Field plots of bush beans sprayed with the bacterium Erwinia herbicola, received the following treatments: (1) control, (2) control + till, (3) burn, (4) burn + till, (5) Kocide (cupric hydroxide), (6) Kocide + till, (7) Agri-strep (streptomycin sulfate), and (8) Agri-strept + till. Leaves and soil from the plots were sampled -1, 1, 5, 8, 12, 15, 19, and 27 days after application of the decontamination treatments. Burning produced a significant and persistent reduction in the number of bacteria whereas tilling, alone or in combination with the biocide treatments, stimulated a significant and persistent reduction in the number of bacteria, whereas tilling, alone or in combination with the biocide treatments, stimulated a significant increase in bacterial populations that persisted for several weeks.

  9. A concise review on smart polymers for controlled drug release.

    PubMed

    Aghabegi Moghanjoughi, Arezou; Khoshnevis, Dorna; Zarrabi, Ali

    2016-06-01

    Design and synthesis of efficient drug delivery systems are of critical importance in health care management. Innovations in materials chemistry especially in polymer field allows introduction of advanced drug delivery systems since polymers could provide controlled release of drugs in predetermined doses over long periods, cyclic and tunable dosages. To this end, researchers have taken advantages of smart polymers since they can undergo large reversible, chemical, or physical fluctuations as responses to small changes in environmental conditions, for instance, in pH, temperature, light, and phase transition. The present review aims to highlight various kinds of smart polymers, which are used in controlled drug delivery systems as well as mechanisms of action and their applications. PMID:26744179

  10. Self-Esteem, Locus of Control, and Student Achievement.

    ERIC Educational Resources Information Center

    Sterbin, Allan; Rakow, Ernest

    The direct effects of locus of control and self-esteem on standardized test scores were studied. The relationships among the standardized test scores and measures of locus of control and self-esteem for 12,260 students from the National Education Longitudinal Study 1994 database were examined, using the same definition of locus of control and…

  11. Controlling Hazardous Releases while Protecting Passengers in Civil Infrastructure Systems

    NASA Astrophysics Data System (ADS)

    Rimer, Sara P.; Katopodes, Nikolaos D.

    2015-11-01

    The threat of accidental or deliberate toxic chemicals released into public spaces is a significant concern to public safety, and the real-time detection and mitigation of such hazardous contaminants has the potential to minimize harm and save lives. Furthermore, the safe evacuation of occupants during such a catastrophe is of utmost importance. This research develops a comprehensive means to address such scenarios, through both the sensing and control of contaminants, and the modeling of and potential communication to occupants as they evacuate. A computational fluid dynamics model is developed of a simplified public space characterized by a long conduit (e.g. airport terminal) with unidirectional ambient flow that is capable of detecting and mitigating the hazardous contaminant (via boundary ports) over several time horizons using model predictive control optimization. Additionally, a physical prototype is built to test the real-time feasibility of this computational flow control model. The prototype is a blower wind-tunnel with an elongated test section with the capability of sensing (via digital camera) an injected `contaminant' (propylene glycol smoke), and then mitigating that contaminant using actuators (compressed air operated vacuum nozzles) which are operated by a set of pressure regulators and a programmable controller. Finally, an agent-based model is developed to simulate ``agents'' (i.e. building occupants) as they evacuate a public space, and is coupled with the computational flow control model such that agents must interact with a dynamic, threatening environment. NSF-CMMI #0856438.

  12. Concurrently adjusting interrelated control parameters to achieve optimal engine performance

    DOEpatents

    Jiang, Li; Lee, Donghoon; Yilmaz, Hakan; Stefanopoulou, Anna

    2015-12-01

    Methods and systems for real-time engine control optimization are provided. A value of an engine performance variable is determined, a value of a first operating condition and a value of a second operating condition of a vehicle engine are detected, and initial values for a first engine control parameter and a second engine control parameter are determined based on the detected first operating condition and the detected second operating condition. The initial values for the first engine control parameter and the second engine control parameter are adjusted based on the determined value of the engine performance variable to cause the engine performance variable to approach a target engine performance variable. In order to cause the engine performance variable to approach the target engine performance variable, adjusting the initial value for the first engine control parameter necessitates a corresponding adjustment of the initial value for the second engine control parameter.

  13. Purpose Plus: Supporting Youth Purpose, Control, and Academic Achievement

    ERIC Educational Resources Information Center

    Pizzolato, Jane Elizabeth; Brown, Elizabeth Levine; Kanny, Mary Allison

    2011-01-01

    Research in the past decade suggests that a persistent achievement gap between students from low-income minority backgrounds and higher-income white backgrounds may be rooted in theories of student motivation and youth purpose. Yet limited research exists regarding the role of purpose on positive youth development as it pertains to academic…

  14. Acid and reduction stimulated logic "and"-type combinational release mode achieved in DOX-loaded superparamagnetic nanogel.

    PubMed

    Song, Meifang; Xue, Yanan; Chen, Lidi; Xia, Xiaoyang; Zhou, Yang; Liu, Lei; Yu, Bo; Long, Sihui; Huang, Shiwen; Yu, Faquan

    2016-08-01

    A superparamagnetic nanogel featured with a logic "and"-type pH/reduction combinational stimulated release mode was fabricated as a drug delivery system by virtue of parallel crosslinking. The disulfide bond and electrostatic interaction between thiolated alginate (SA-SH) and thiolated/aminated iron oxide nanoparticles (SH-MION-NH2) were employed to achieve the mechanism. The obtained DOX-loaded magnetic nanogel is 122.7±20.3nm in size with superparamagnetism. The combinational conditions of pH5.0/10mM glutathione (GSH) stimulated a significantly high accumulative release. However, either pH7.4/10mM (GSH) or pH5.0 alone induced much low release. This verified the typical logic "and"-type combinationally stimulated release mode. In vitro cytotoxicity tests clearly illustrated the effective selectivity of killing the human cervical cancer cells (HeLa) with IC50 of 1.01μg/mL and the human hepatoma cells (HepG2) with IC50 of 1.57μg/mL but significantly low cytotoxicity to the cercopithecus aethiops kidney cells (Vero). CLSM presented the internationalization of the nanogel into cytoplasm and nuclei with time. In vivo investigation revealed that the selective intratumoral accumulation and antitumor efficacy were considerably advantageous over free DOX whereas low systemic toxicity exhibited up-regulated security as compared to free DOX. Overall, the DOX-loaded magnetic nanogel with enhanced antitumor efficacy and down-regulated adverse effect was a promising nanoplatform for the clinical chemotherapy of malignancy. PMID:27157762

  15. Evaluation of a soil incubation method to characterize nitrogen release patterns of slow- and controlled-release fertilizers.

    PubMed

    Medina, L Carolina; Sartain, Jerry B; Obreza, Thomas A; Hall, William L; Thiex, Nancy J

    2014-01-01

    Several technologies have been proposed to characterize the nutrient release patterns of slow-release fertilizers (SRF) and controlled-release fertilizers (CRF) during the last few decades. These technologies have been developed mainly by manufacturers, and are product-specific, based on the regulation and analysis of each SRF and CRF product. Despite previous efforts to characterize SRF and CRF materials, no standardized, validated method exists to assess their nutrient release patterns. However, the increased production and distribution of these materials in specialty and nonspecialty markets requires an appropriate method to verify product claims and material performance. A soil incubation column leaching procedure was evaluated to determine its suitability as a standard method to estimate nitrogen (N) release patterns of SRFs and CRFs during 180 days. The influence of three soil/sand ratios, three incubation temperatures, and four soils on method behavior was assessed using five SRFs and three CRFs. In general, the highest soil/sand ratio increased the N release rate of all materials, but this effect was more marked for the SRFs. Temperature had the greatest influence on N release rates. For CRFs, the initial N release rates and the percentage N released/day increased as temperature increased. For SRFs, raising the temperature from 25 to 35 degreesC increased initial N release rate and the total cumulative N released, and almost doubled the percentage released/day. The percentage N released/day from all products generally increased as the texture of the soil changed from sandy to loamy (lowa>California>Pennsylvania>Florida). The soil incubation technique was demonstrated to be robust and reliable for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and variations in soil/sand ratio, temperature, and soil had little effect on the results. PMID:25051610

  16. Leveraging electrokinetics for the active control of dendritic fullerene-1 release across a nanochannel membrane

    PubMed Central

    Bruno, Giacomo; Geninatti, Thomas; Hood, R. Lyle; Fine, Daniel; Scorrano, Giovanni; Schmulen, Jeffrey; Hosali, Sharath; Ferrari, Mauro; Grattoni, Alessandro

    2015-01-01

    General adoption of advanced treatment protocols such as chronotherapy will hinge on progress in drug delivery technologies that provide precise temporal control of therapeutic release. Such innovation is also crucial to future medicine approaches such as telemedicine. Here we present a nanofluidic membrane technology capable of achieving active and tunable control of molecular transport through nanofluidic channels. Control was achieved through application of an electric field between two platinum electrodes positioned on either surface of a 5.7 nm nanochannel membrane designed for zero-order drug delivery. Two electrode configurations were tested: laser-cut foils and electron beam deposited thin-films, configurations capable of operating at low voltage (≤1.5 V), and power (100 nW). Temporal, reproducible tuning and interruption of dendritic fullerene 1 (DF-1) transport was demonstrated over multi-day release experiments. Conductance tests showed limiting currents in the low applied potential range, implying ionic concentration polarization (ICP) at the interface between the membrane’s micro- and nanochannels, even in concentrated solutions (≤ 1 M NaCl). The ability of this nanotechnology platform to facilitate controlled delivery of molecules and particles has broad applicability to next-generation therapeutics for numerous pathologies, including autoimmune diseases, circadian dysfunction, pain, and stress, among others. PMID:25707848

  17. Development and Evaluation of Thymol Microparticles Using Cellulose Derivatives as Controlled Release Dosage form.

    PubMed

    Zamani, Zahra; Alipour, Daryoush; Moghimi, Hamid Reza; Mortazavi, Seyed Ali Reza; Saffary, Mostafa

    2015-01-01

    Thymol, an important and advantageous component of many essential oils, has been applied as an antimicrobial agent in animals. To increase the duration of action of this compound in ruminants, it was decided here to prepare a controlled release carrier for thymol. Hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC) were used as the matrix polymer here. Mixtures of thymol with eight different ratios of these polymers were then prepared using emulsion solvent evaporation method (F1 to F8). The prepared microparticles were evaluated for production yield, entrapment efficiency, drug content, particle size, drug release behavior, release kinetics (zero order, first order and Fickian matrix diffusion for spheres) and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Mean particle size of microparticles was 1.03 ± 0.02 mm. SEM study revealed that the microparticles were slightly irregular, rough and porous. The formulation with HPMC: EC ratio of 5:1 (F6) showed the highest drug loading (38.8%) and entrapment efficiency (61.2%). This formulation also showed optimum in-vitro drug release. The best fit of release kinetics was achieved with Fickian matrix diffusion for spheres (linear amount released vs t(0.43)). The FTIR spectroscopic and DSC studies show possible interaction between drug and polymers. In this study, thymol was successfully loaded in microparticles prepared from HPMC and EC. These microparticles can be used in further trials to evaluate the effect of slow release thymol on rumen fermentation parameters in ruminants. PMID:26664369

  18. Development and Evaluation of Thymol Microparticles Using Cellulose Derivatives as Controlled Release Dosage form

    PubMed Central

    Zamani, Zahra; Alipour, Daryoush; Moghimi, Hamid Reza; Mortazavi, Seyed Ali Reza; Saffary, Mostafa

    2015-01-01

    Thymol, an important and advantageous component of many essential oils, has been applied as an antimicrobial agent in animals. To increase the duration of action of this compound in ruminants, it was decided here to prepare a controlled release carrier for thymol. Hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC) were used as the matrix polymer here. Mixtures of thymol with eight different ratios of these polymers were then prepared using emulsion solvent evaporation method (F1 to F8). The prepared microparticles were evaluated for production yield, entrapment efficiency, drug content, particle size, drug release behavior, release kinetics (zero order, first order and Fickian matrix diffusion for spheres) and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Mean particle size of microparticles was 1.03 ± 0.02 mm. SEM study revealed that the microparticles were slightly irregular, rough and porous. The formulation with HPMC: EC ratio of 5:1 (F6) showed the highest drug loading (38.8%) and entrapment efficiency (61.2%). This formulation also showed optimum in-vitro drug release. The best fit of release kinetics was achieved with Fickian matrix diffusion for spheres (linear amount released vs t0.43). The FTIR spectroscopic and DSC studies show possible interaction between drug and polymers. In this study, thymol was successfully loaded in microparticles prepared from HPMC and EC. These microparticles can be used in further trials to evaluate the effect of slow release thymol on rumen fermentation parameters in ruminants. PMID:26664369

  19. Modeling controlled nutrient release from a population of polymer coated fertilizers: statistically based model for diffusion release.

    PubMed

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A statistically based model for describing the release from a population of polymer coated controlled release fertilizer (CRF) granules by the diffusion mechanism was constructed. The model is based on a mathematical-mechanistic description of the release from a single granule of a coated CRF accounting for its complex and nonlinear nature. The large variation within populations of coated CRFs poses the need for a statistically based approach to integrate over the release from the individual granules within a given population for which the distribution and range of granule radii and coating thickness are known. The model was constructed and verified using experimentally determined parameters and release curves of polymer-coated CRFs. A sensitivity analysis indicated the importance of water permeability in controlling the lag period and that of solute permeability in governing the rate of linear release and the total duration of the release. Increasing the mean values of normally distributed granule radii or coating thickness, increases the lag period and the period of linear release. The variation of radii and coating thickness, within realistic ranges, affects the release only when the standard deviation is very large or when water permeability is reduced without affecting solute permeability. The model provides an effective tool for designing and improving agronomic and environmental effectiveness of polymer-coated CRFs. PMID:12785533

  20. Controlling open quantum systems: tools, achievements, and limitations

    NASA Astrophysics Data System (ADS)

    Koch, Christiane P.

    2016-06-01

    The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge of preserving relevant nonclassical features at the level of device operation. A major obstacle is decoherence, which is caused by interaction with the environment. Optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence. Here we review recent advances in optimal control methodology that allow typical tasks in device operation for open quantum systems to be tackled and discuss examples of relaxation-optimized dynamics. Optimal control theory is also a useful tool to exploit the environment for control. We discuss examples and point out possible future extensions.

  1. Controlling open quantum systems: tools, achievements, and limitations.

    PubMed

    Koch, Christiane P

    2016-06-01

    The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge of preserving relevant nonclassical features at the level of device operation. A major obstacle is decoherence, which is caused by interaction with the environment. Optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence. Here we review recent advances in optimal control methodology that allow typical tasks in device operation for open quantum systems to be tackled and discuss examples of relaxation-optimized dynamics. Optimal control theory is also a useful tool to exploit the environment for control. We discuss examples and point out possible future extensions. PMID:27143501

  2. Nanoparticle encapsulation and controlled release of a hydrophobic kinase inhibitor: Three stage mathematical modeling and parametric analysis.

    PubMed

    Lucero-Acuña, Armando; Guzmán, Roberto

    2015-10-15

    A mathematical model of drug release that incorporates the simultaneous contributions of initial burst, nanoparticle degradation-relaxation and diffusion was developed and used to effectively describe the release of a kinase inhibitor and anticancer drug, PHT-427. The encapsulation of this drug into PLGA nanoparticles was performed by following the single emulsion-solvent evaporation technique and the release was determined in phosphate buffer pH 7.4 at 37 °C. The size of nanoparticles was obtained in a range of 162-254 nm. The experimental release profiles showed three well defined phases: an initial fast drug release, followed by a nanoparticle degradation-relaxation slower release and then a diffusion release phase. The effects of the controlled release most relevant parameters such as drug diffusivity, initial burst constant, nanoparticle degradation-relaxation constant, and the time to achieve a maximum rate of drug release were evaluated by a parametrical analysis. The theoretical release studies were corroborated experimentally by evaluating the cytotoxicity effectiveness of the inhibitor AKT/PDK1 loaded nanoparticles over BxPC-3 pancreatic cancer cells in vitro. These studies show that the encapsulated inhibitor AKT/PDK1 in the nanoparticles is more accessible and thus more effective when compared with the drug alone, indicating their potential use in chemotherapeutic applications. PMID:26216413

  3. Floating tablets for controlled release of ofloxacin via compression coating of hydroxypropyl cellulose combined with effervescent agent.

    PubMed

    Qi, Xiaole; Chen, Haiyan; Rui, Yao; Yang, Fengjiao; Ma, Ning; Wu, Zhenghong

    2015-07-15

    To prolong the residence time of dosage forms within gastrointestinal trace until all drug released at desired rate was one of the real challenges for oral controlled-release drug delivery system. Herein, we developed a fine floating tablet via compression coating of hydrophilic polymer (hydroxypropyl cellulose) combined with effervescent agent (sodium bicarbonate) to achieve simultaneous control of release rate and location of ofloxacin. Sodium alginate was also added in the coating layer to regulate the drug release rate. The effects of the weight ratio of drug and the viscosity of HPC on the release profile were investigated. The optimized formulations were found to immediately float within 30s and remain lastingly buoyant over a period of 12 h in simulated gastric fluid (SGF, pH 1.2) without pepsin, indicating a satisfactory floating and zero-order drug release profile. In addition, the oral bioavailability experiment in New Zealand rabbits showed that, the relative bioavailability of the ofloxacin after administrated of floating tablets was 172.19%, compared to marketed common release tablets TaiLiBiTuo(®). These results demonstrated that those controlled-released floating tables would be a promising gastro-retentive delivery system for drugs acting in stomach. PMID:25956047

  4. Analgesic efficacy of controlled-release oxycodone in postoperative pain.

    PubMed

    Sunshine, A; Olson, N Z; Colon, A; Rivera, J; Kaiko, R F; Fitzmartin, R D; Reder, R F; Goldenheim, P D

    1996-07-01

    The efficacy and safety of graded doses (10, 20, and 30 mg) of controlled-release (CR) oxycodone was compared with that of immediate-release (IR) oxycodone (15 mg), immediate-release oxycodone 10 mg in combination with acetaminophen 650 mg (APAP), and placebo in a single-dose, double-blind, randomized, parallel-group study. The participants, 182 inpatients experiencing moderate to severe pain after abdominal or gynecologic surgery, provided hourly ratings of pain intensity and relief for 12 hours after administration. All active treatments were significantly superior to placebo for many hourly measurements and for the sum of pain intensity differences (SPID) and total pain relief (TOTPAR). A dose response was found among the three levels of CR oxycodone for pain relief and peak pain intensity difference (PID), with the 20- and 30-mg doses being significantly better than the 10-mg dose. For all active treatments, peak PID and peak pain relief occurred approximately 2 to 4 hours after administration. The median time to onset of relief was 32 minutes for oxycodone plus APAP, 41 minutes for IR oxycodone, and 46 minutes for CR oxycodone 30 mg. Duration of pain relief showed that the 10-, 20-, and 30-mg doses of CR oxycodone had durations of action of 10 to 12 hours compared with IR oxycodone and oxycodone plus APAP (both approximately 7 hours). Typical adverse events, particularly somnolence, occurred in all active treatment groups. Treatment with CR oxycodone was safe and effective in this study, and its characteristics will be beneficial in the treatment of pain. PMID:8844441

  5. Development of Active Control Method for Supercooling Releasing of Water

    NASA Astrophysics Data System (ADS)

    Mito, Daisuke; Kozawa, Yoshiyuki; Tanino, Masayuki; Inada, Takaaki

    We have tested the prototype ice-slurry generator that enables both production of supercooled water (-2°C) and releasing of its supercooling simultaneously and continuously in a closed piping system. In the experiment, we adopted the irradiation of ultrasonic wave as an active control method of triggering for supercooling releasing, and evaluated the reliability for a practical use compared with the seed ice-crystal trigger. As the results, it has been confirmed that the ultrasonic wave trigger acts assuredly at the same level of degree of supercooling as that by using the seed ice-crystal Trigger. Moreover, it can be found that the ultrasonic wave trigger has the advantage of removing the growing ice-crystals on the pipe wall at the same time. Finally, we have specified the bombardment condition of ultrasonic wave enough to make continuously the ice-slurry in a closed system as the output surface power density > 31.4kW/m2 and the superficial bombardment time > 4.1sec. We have also demonstrated the continuous ice-slurry making for more than 6hours by using the refrigerator system with the practical scale of 88kW.

  6. Non-polymeric coatings to control drug release from metallic coronary stents

    NASA Astrophysics Data System (ADS)

    Gupta, Celia Edith Macias

    Percutaneous transluminal coronary angiography (PTCA) is a procedure used to re-open narrowed coronary arteries. During PTCA, a coronary stent is expanded inside a diseased vessel and serves as a scaffold to keep the artery open. The major drawback of stenting is restenosis---a re-narrowing of the vessel resulting from the hyperproliferation of smooth muscle cells. Drug eluting stents (DES) reduce the rate of restenosis compared to bare metal stents. Paclitaxel (PAT) is commonly used in DES for its ability to prevent restenosis. However, DES have been associated with thrombosis due to the polymer carrier that controls drug delivery. Therefore, there is a need to change the drug delivery mechanisms to eliminate the need of polymers. The goal of this dissertation is to develop a novel polymer-free drug eluting stent that controls drug release using nanoscale metal coatings. The coating was designed to release PAT as the metal slowly degrades in biological conditions. Once all the Paclitaxel has eluted from the surface, the coating will continue to degrade until the final result is a bare metal stent. The results of this study include a novel non-polymeric drug delivery system using nanoscale coatings that release Paclitaxel at a rate similar to commercial stents, as well as the biocompatibility and efficacy of these coatings. The non-polymeric drug delivery system described here achieved a Paclitaxel release profile equivalent to clinically available Paclitaxel-eluting stents and effectively inhibits smooth muscle cell proliferation, thereby completely eliminating the need for polymers to control drug release from coronary stents.

  7. Achieving process control through improved grinding techniques for ferrite materials

    SciTech Connect

    Bruce, J.

    1995-09-01

    In manufacturing soft ferrite materials the particle size of the raw material has a significant impact on the reactivity of calcination. The control of particle size distribution and final formulation at wet milling after calcining impacts the reactivity during sintering and the magnetic properties of the final product. This paper will deal with steps taken to improve process control during the grinding operations of raw material and calcine in soft ferrite production. Equipment modifications as well as changes to the grinding and material handling techniques will be included. All examples of process control and improvements will be supported by data.

  8. Debris control design achievements of the booster separation motors

    NASA Technical Reports Server (NTRS)

    Smith, G. W.; Chase, C. A.

    1985-01-01

    The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented.

  9. Controlled drug release from biodegradable thermoresponsive physical hydrogel nanofibers.

    PubMed

    Loh, Xian Jun; Peh, Priscilla; Liao, Susan; Sng, Colin; Li, Jun

    2010-04-19

    Hydrogel nanofiber mats based on thermoresponsive multiblock poly(ester urethane)s comprising poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), and poly(epsilon-caprolactone) (PCL) segments were fabricated by electrospinning. The hydrogel nanofiber mats were more water absorbent under cold conditions and shrunk when exposed to higher temperatures. The rate of protein release could be controlled by changing the temperature of the nanofiber environment. Cell culture studies on the nanofiber mats were carried out using human dermal fibroblasts, and healthy cell morphology was observed. The adherent viable cells were quantified by MTS after rinsing in excess buffer solution. The results showed that these nanofiber scaffolds supported excellent cell adhesion, comparable with the pure PCL nanofibers. The increased hydrophilicity of these hydrogel nanofiber mats led to a more rapid hydrolytic degradation, compared with the pure PCL nanofiber mats. These hydrogel nanofiber scaffolds could potentially be used as thermoresponsive biodegradable supporting structures for skin tissue engineering applications. PMID:20064568

  10. An active control strategy for achieving weak radiator structures

    SciTech Connect

    Naghshineh, K. . Acoustics and Radar Technology Lab.); Koopmann, G.H. . Center for Acoustics and Vibration)

    1994-01-01

    A general control strategy is presented for active suppression of total radiated sound power from harmonically excited structures based on the measurement of their response. Using the measured response of the structure together with knowledge of its structural mobility, and equivalent primary excitation force is found at discrete points along the structure. Using this equivalent primary force and performing a quadratic optimization of the power radiated form the structure, a set of control forces is found at selected points on the structure that results in minimum radiated sound power. A numerical example of this strategy is presented for a simply supported beam in a rigid baffle excited by a harmonic plane wave incident at an oblique angle. A comparison of the response of the beam with and without control forces shows a large reduction in the controlled response displacement magnitude. In addition, as the result of the action of the control forces, the magnitude of the wave number spectrum of the beam's response in the supersonic region is decreased substantially. The effect of the number and location of the actuators on reductions in sound power level is also studied. The actuators located at the anti-nodes of structural modes within the supersonic region together with those located near boundaries are found to be the most effective in controlling the radiation of sound from a structure.

  11. CONTROLLED RELEASE OF REPIFERMIN® FROM POLYELECTROLYTE COMPLEXES STIMULATES ENDOTHELIAL CELL PROLIFERATION

    PubMed Central

    Huang, Min; Berkland, Cory

    2014-01-01

    The therapeutic value of many growth factors is often hindered by the narrow therapeutic index and sustained concentrations required for efficacy. Controlled release approaches provide a valuable tool to achieve these goals; however, growth factor stability must be maintained. Repifermin® is a truncated form of fibroblast growth factor-10, also known as keratinocyte growth factor-2, that exhibits promise in wound healing applications; however, controlled release formulation presents a challenge for this labile protein. Taking advantage of the heparin-binding motif of this class of biopharmaceuticals, Repifermin® was effectively stabilized and packaged in polyelectrolyte complexes. In the presence of dextran sulfate, the unfolding temperature of this growth factor was increased by ~10°C as confirmed by a variety of spectroscopic techniques. Dextran sulfate with bound Repifermin® was then complexed with several polycations (chitosan, poly-L-lysine, and polyethylenimine) resulting in the formation of ~250 nm polyelectrolyte complexes that entrapped the protein with ~70–80% efficiency. Release was controlled for more than 10 days and the mitogenic activity of Repifermin® on human umbilical cord vascular endothelial cells was significantly enhanced, whereas no effect was noted for free Repifermin®. PMID:18425807

  12. Iron/dextran sulfate multilayered microcapsules for controlled release of 10-hydroxycamptothecin.

    PubMed

    Guo, Shenglei; Zheng, Jian; Dong, Jing; Guo, Na; Jing, Lijia; Yue, Xiuli; Yan, Xiufeng; Wang, Yang; Dai, Zhifei

    2011-10-01

    Stable 10-hydroxycamptothecin (HCPT) microcrystals with a length of about 5-10μm and a ζ-potential of -38.5mV were produced by pH-induced reprecipitation in presence of a stabilizer hydroxypropylmethylcellulose. Sequential layer growth was achieved by the layer-by-layer (LbL) assembly of Fe(3+) and dextran sulfate (DS) on the surface of HCPT microcrystals via both electrostatic interaction and chemical complexation process. The satisfactory drug loading content (67.2±0.82%) as well as high encapsulation efficiency (60.56±0.82%) for four bilayers of Fe(3+)/DS coating was achieved. Both in vitro and in vivo release study revealed that the release time increased as the number of deposited Fe(3+)/DS bilayers increased. These results indicated that such iron-polysaccharide multilayered microcapsules can be a promising approach for the construction of an effective controlled release delivery system of HCPT as well as other drugs with potential cytotoxicity or short half-life time. PMID:21664925

  13. Achievement Goals and Emotions: The Mediational Roles of Perceived Progress, Control, and Value

    ERIC Educational Resources Information Center

    Hall, Nathan C.; Sampasivam, Lavanya; Muis, Krista R.; Ranellucci, John

    2016-01-01

    Background: The link between achievement goals and achievement emotions is well established; however, research exploring potential mediators of this relationship is lacking. The control-value theory of achievement emotions (Pekrun, 2006, "Educational Psychology Review," 18, 315) posits that perceptions of control and value mediate the…

  14. Achieving Acceptable Air Quality: Some Reflections on Controlling Vehicle Emissions

    NASA Astrophysics Data System (ADS)

    Calvert, J. G.; Heywood, J. B.; Sawyer, R. F.; Seinfeld, J. H.

    1993-07-01

    Motor vehicle emissions have been and are being controlled in an effort to abate urban air pollution. This article addresses the question: Will the vehicle exhaust emission control and fuel requirements in the 1990 Clean Air Act Amendments and the California Air Resources Board regulations on vehicles and fuels have a significant impact? The effective control of in-use vehicle emissions is the key to a solution to the motor vehicle part of the urban air pollution problem for the next decade or so. It is not necessary, except perhaps in Southern California, to implement extremely low new car emission standards before the end of the 20th century. Some of the proposed gasoline volatility and composition changes in reformulated gasoline will produce significant reductions in vehicle emissions (for example, reduced vapor pressure, sulfur, and light olefin and improved high end volatility), whereas others (such as substantial oxygenate addition and aromatics reduction) will not.

  15. Externally Controlled Triggered-Release of Drug from PLGA Micro and Nanoparticles

    PubMed Central

    Hua, Xin; Tan, Shengnan; Bandara, H. M. H. N.; Fu, Yujie; Liu, Siguo; Smyth, Hugh D. C.

    2014-01-01

    Biofilm infections are extremely hard to eradicate and controlled, triggered and controlled drug release properties may prolong drug release time. In this study, the ability to externally control drug release from micro and nanoparticles was investigated. We prepared micro/nanoparticles containing ciprofloxacin (CIP) and magnetic nanoparticles encapsulated in poly (lactic-co-glycolic acid) PLGA. Both micro/nanoparticles were observed to have narrow size distributions. We investigated and compared their passive and externally triggered drug release properties based on their different encapsulation structures for the nano and micro systems. In passive release studies, CIP demonstrated a fast rate of release in first 2 days which then slowed and sustained release for approximately 4 weeks. Significantly, magnetic nanoparticles containing systems all showed ability to have triggered drug release when exposed to an external oscillating magnetic field (OMF). An experiment where the OMF was turned on and off also confirmed the ability to control the drug release in a pulsatile manner. The magnetically triggered release resulted in a 2-fold drug release increase compared with normal passive release. To confirm drug integrity following release, the antibacterial activity of released drug was evaluated in Pseudomonas aeruginosa biofilms in vitro. CIP maintained its antimicrobial activity after encapsulation and triggered release. PMID:25479357

  16. Controlled thermal-sensitive liposomes release on a disposable microfluidic device.

    PubMed

    Meng, Long; Deng, Zhiting; Niu, Lili; Cai, Feiyan; Zheng, Hairong

    2015-08-01

    High intensity focused ultrasound (HIFU) triggered drug release as one of promising approaches for local drug delivery is gaining more attention as ultrasound allows the deposition of the thermal and mechanical energies to a specific localized region in a noninvasive manner. Release of encapsulated drugs from a nano-carrier such as liposome could further achieve a higher local drug concentration and reduce the toxicity effects under the stimulus of temperature elevation. This paper presents a micro HIFU (MHIFU) microfluidic device to enable mimic the bulky HIFU transmission system without the need of high power consumption and control the release of low temperature-sensitive liposomes (LTSL). Moreover, by adjusting the input signal, the temperature can be elevated and maintained at 37°C, 42°C and 50°C precisely with the error of ±0.3°C. The flow cytometry results show that HIFU-mediated drug delivery lead to an increase in uptake compared to water incubation-induced drug release at 42°C. Microfluidic technology may offer a promising alternative method for investigation of the complex dynamics between ultrasound and organisms in an ultramicroscopic manner. PMID:26737637

  17. Cognitive Control Predicts Academic Achievement in Kindergarten Children

    ERIC Educational Resources Information Center

    Coldren, Jeffrey T.

    2013-01-01

    Children's ability to shift behavior in response to changing environmental demands is critical for successful intellectual functioning. While the processes underlying the development of cognitive control have been thoroughly investigated, its functioning in an ecologically relevant setting such as school is less well understood. Given the alarming…

  18. ACHIEVING IRRIGATION RETURN FLOW QUALITY CONTROL THROUGH IMPROVED LEGAL SYSTEMS

    EPA Science Inventory

    The key to irrigated agricultural return flow quality control is proper utilization and management of the resource itself, and an accepted tool in out society is the law. This project is designed to develop legal alternatives that will facilitate the implementation of improved wa...

  19. Antibacterial activities and release kinetics of a newly developed recoverable controlled agent-release system.

    PubMed

    Ehara, A; Torii, M; Imazato, S; Ebisu, S

    2000-03-01

    We attempted to develop a resin with a recoverable antibacterial activity based on the desorption/adsorption of a cationic bactericide by the ion-exchange mechanism. The aims of this study were to investigate the release kinetics of the agent and the antibacterial activity of this newly designed resin system. An experimental resin was prepared by the addition of methacrylic acid as a cation-exchanger and a cationic antibacterial agent, cetylpyridinium chloride (CPC), to triethyleneglycol dimethacrylate. The amount of CPC desorbed from the experimental resin into buffer solutions at pH 4-8 was measured. The adsorption of CPC to control resin and re-adsorption of CPC to the experimental resin, which had once desorbed the agent, were also determined. The antibacterial activity of experimental resin against Streptococcus mutans was evaluated, and the relationship between bacterial acid production and antibacterial effect was assessed. The experimental resin desorbed CPC at pH < or = 6, and the amount of agent desorbed increased with increasing acidity. The control resin adsorbed CPC when immersed in CPC aqueous solution at a rate determined by the concentration of the agent and immersion time. The experimental resin, once desorbed CPC, could re-adsorb the bactericide by being exposed to a solution of the agent. Less plaque formed on the experimental resin, and the growth and survival of S. mutans was inhibited in the condition in which acid was produced. These results demonstrate that the resin system proposed was able to desorb and re-adsorb the cationic bactericide by an ion-exchange mechanism and could show an inhibitory effect on S. mutans growth and plaque formation. PMID:10765955

  20. Achievements in and Challenges of Tuberculosis Control in South Korea.

    PubMed

    Kim, Ji Han; Yim, Jae-Joon

    2015-11-01

    After the Korean War (1950-1953), nearly 6.5% of South Korea's population had active tuberculosis (TB). In response, South Korea implemented the National Tuberculosis Program in 1962. From 1965 to 1995, the prevalence of bacteriologically confirmed pulmonary TB in South Korea decreased from 940 to 219 cases per 100,000 population. Astounding economic growth might have contributed to this result; however, TB incidence in South Korea remains the highest among high-income countries. The rate of decrease in TB incidence seems to have slowed over the past 15 years. A demographic shift toward an older population, many of whom have latent TB and various concurrent conditions, is challenging TB control efforts in South Korea. The increasing number of immigrants also plays a part in the prolonged battle against TB. A historical review of TB in South Korea provides an opportunity to understand national TB control efforts that are applicable to other parts of the world. PMID:26485188

  1. Comparison in vitro felodipine release rate from the original versus generic product with controlled release of the drug.

    PubMed

    Vetchy, David; Vetcha, Martina; Rabiskova, Miloslava; Gryczova, Eva; Bartosikova, Lenka

    2007-01-01

    After patent protection of original brand is over, there are a lot of generic products occurring on the pharmaceutical market. It may be the way to reduce the price, but on the other hand, one should expect the same quality and almost identity with original brand, because the development of generic drugs is based on pharmacological properties of the original brand. The aim of this study was to compare the similarity of two products with controlled release of felodipine--generic product Presid and original brand Plendil--which are commercially available in Czech Republic, based on in vitro dissolution testing. The dissolution test in three dissolution media of increasing pH (1.2, 4.5, and 6.5) for the simulation of physiological pH within the gastrointestinal tract confirmed controlled release of felodipine from the original product Plendil ER 5 mg and Plendil ER 10 mg during the period of 24 hours. The release of felodipine from generic products Presid 5 mg and Presid 10 mg was not controlled for 24 hours as it is indicated in the information leaflet. In the generic products, felodipine release was controlled just for 12 or 18 hours and in this respect did not show similarity with the original brand. Since patients take the drug just once a day in the morning, the controlled release of felodipine, which lasts only 12 to 18 hours, can cause insufficient blood pressure control especially in the most critical morning hours and higher cardiovascular risk. PMID:17485960

  2. Incorporation of Proteinase Inhibitors into Silk-Based Delivery Devices for Enhanced Control of Degradation and Drug Release

    PubMed Central

    Pritchard, Eleanor M.; Valentin, Thomas; Boison, Detlev; Kaplan, David L.

    2010-01-01

    Controlling the rate of silk degradation is critical to its potential use in biomedical applications, including drug delivery and tissue engineering. The effect of protease concentration on accelerating degradation, and the use of ethylenediamine tetraacetic acid (EDTA) on reducing rates of degradation and on drug release from silk-based drug carriers was studied. Increased rates of proteolysis resulted in increased dye release from silk carriers, while EDTA release from the silk carriers inhibited proteolysis. The sustained release of EDTA from silk carriers in combination with the release of the small molecule anticonvulsant adenosine was investigated in vitro. This combination of factors resulted in delayed release of adenosine by inhibiting proteolytic activity. These results introduce a promising strategy to control drug delivery through the regulation of silk degradation rate, achieved via manipulation of local proteolytic activity. This ability to modulate enzyme function could be applicable to a range of silk biomaterial formats as well as other biodegradable polymers where enzymatic functions control biomaterial degradation and drug release rates. PMID:20950854

  3. Factors controlling phosphorus release from sediments in coastal archipelago areas.

    PubMed

    Puttonen, Irma; Kohonen, Tuula; Mattila, Johanna

    2016-07-15

    In coastal archipelago areas of the northern Baltic Sea, significantly higher phosphate concentrations (6.0±4.5μmol/l, mean±SD) were measured in water samples close to the sediment surface compared with those from 1m above the seafloor (1.6±2.0μmol/l). The results indicated notable phosphate release from sediments under the bottom water oxygen concentrations of up to 250μmol/l, especially in areas that had experienced recent temporal fluctuation between oxic and hypoxic/anoxic conditions. No single factor alone was found to control the elevated PO4-P concentrations in the near-bottom water. In addition to the oxygen in the water, the contents of potentially mobile phosphorus fractions, grain-size, the organic content at the sediment surface, and the water depth were all important factors controlling the internal loading of phosphorus. The complexity of this process needs to be accounted for in assessments of the internal loading of phosphorus and in potential mitigation plans. PMID:27184132

  4. Silylated Precision Particles for Controlled Release of Proteins

    PubMed Central

    Khodabandehlou, Khosrow; Kumbhar, Amar S.; Habibi, Sohrab; Pandya, Ashish A.; Luft, J. Christopher; Khan, Saad A.; DeSimone, Joseph M.

    2015-01-01

    With the recent advances in the development of novel protein based therapeutics, controlled delivery of these biologics is an important area of research. Herein, we report the synthesis of microparticles from bovine serum albumin (BSA) as a model protein using Particle Replication in Non-wetting Templates (PRINT) with specific size and shape. These particles were functionalized at room temperature using multifunctional chlorosilane that cross-link the particles to render them to slowly-dissolving in aqueous media. Mass spectrometric study of the reaction products of diisopropyldichlorosilane with individual components of the particles revealed that they are capable of reacting and forming cross-links. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were also used to confirm the functionalization of the particles. Cross sectional analysis using focused ion beam (FIB) and EDS proved that the functionalization occurs throughout the bulk of the particles and is not just limited to the surface. Circular dichroism data confirmed that the fraction of BSA molecules released from the particles retains its secondary structure thereby indicating that the system can be used for delivering protein based formulations while controlling the dissolution kinetics. PMID:25742193

  5. Degradable thermoresponsive nanogels for protein encapsulation and controlled release.

    PubMed

    Bhuchar, Neha; Sunasee, Rajesh; Ishihara, Kazuhiko; Thundat, Thomas; Narain, Ravin

    2012-01-18

    Reversible addition-fragmentation chain transfer (RAFT) polymerization technique was used for the fabrication of stable core cross-linked micelles (CCL) with thermoresponsive and degradable cores. Well-defined poly(2-methacryloyloxyethyl phosphorylcholine), poly(MPC) macroRAFT agent, was first synthesized with narrow molecular weight distribution via the RAFT process. These CCL micelles (termed as nanogels) with hydrophilic poly(MPC) shell and thermoresponsive core consisting of poly(methoxydiethylene glycol methacrylate) (poly(MeODEGM) and poly(2-aminoethyl methacrylamide hydrochloride) (poly(AEMA) were then obtained in a one-pot process by RAFT polymerization in the presence of an acid degradable cross-linker. These acid degradable nanogels were efficiently synthesized with tunable sizes and low polydispersities. The encapsulation efficiencies of the nanogels with different proteins such as insulin, BSA, and β-galactosidase were studied and found to be dependent of the cross-linker concentration, size of protein, and the cationic character of the nanogels imparted by the presence of AEMA in the core. The thermoresponsive nature of the synthesized nanogels plays a vital role in protein encapsulation: the hydrophilic core and shell of the nanogels at low temperature allow easy diffusion of the proteins inside out and, with an increase in temperature, the core becomes hydrophobic and the nanogels are easily separated out with entrapped protein. The release profile of insulin from nanogels at low pH was studied and results were analyzed using bicinchoninic assay (BCA). Controlled release of protein was observed over 48 h. PMID:22171688

  6. Solid lipid budesonide microparticles for controlled release inhalation therapy.

    PubMed

    Mezzena, Matteo; Scalia, Santo; Young, Paul M; Traini, Daniela

    2009-12-01

    A solid lipid microparticle system containing budesonide was prepared by oil in water emulsification followed by spray drying. The solid lipid system was studied in terms of morphology, particle size distribution, crystallinity, thermal properties, aerosol performance, and dissolution/diffusion release. The microparticle system was also compared to conventional spray-dried crystalline and amorphous budesonide samples. The particle size distributions of the crystalline, amorphous, and solid lipid microparticles, measured by laser diffraction, were similar; however, the microparticle morphology was more irregular than the spray-dried drug samples. The thermal response of the solid lipid microparticles suggested polymorphic transition and melting of the lipid, glycerol behenate (at approximately 48 degrees C and approximately 72 degrees C). No budesonide melting or crystallisation peaks were observed, suggesting that the budesonide was integrated into the matrix. X-ray powder diffraction patterns of the crystalline and amorphous budesonide were consistent with previous studies while the solid lipid microparticles showed two peaks, at approximately 21.3 and 23.5 2theta suggesting the metastable sub-alpha and primarily beta' form. Analysis of the in vitro diffusion/dissolution of the formulations was studied using a flow through model and curves analysed using difference/similarity factors and fitted using the Higuchi model. Regression analysis of this data set indicated differences in the t (0.5), where values of 49.7, 35.3, and 136.9 min were observed for crystalline, amorphous, and the solid lipid microparticles, respectively. The aerosol performance (<5 microm), measured by multistage liquid impinger, was 29.5%, 27.3%, and 21.1 +/- 0.6% for the crystalline, amorphous, and the solid lipid microparticles, respectively. This study has shown that solid lipid microparticles may provide a useful approach to controlled release respiratory therapy. PMID:19908147

  7. Optimization Correction Strength Using Contra Bending Technique without Anterior Release Procedure to Achieve Maximum Correction on Severe Adult Idiopathic Scoliosis

    PubMed Central

    Rahyussalim, Ahmad Jabir; Saleh, Ifran; Purnaning, Dyah; Kurniawati, Tri

    2016-01-01

    Adult scoliosis is defined as a spinal deformity in a skeletally mature patient with a Cobb angle of more than 10 degrees in the coronal plain. Posterior-only approach with rod and screw corrective manipulation to add strength of contra bending manipulation has correction achievement similar to that obtained by conventional combined anterior release and posterior approach. It also avoids the complications related to the thoracic approach. We reported a case of 25-year-old male adult idiopathic scoliosis with double curve. It consists of main thoracic curve of 150 degrees and lumbar curve of 89 degrees. His curve underwent direct contra bending posterior approach using rod and screw corrective manipulation technique to achieve optimal correction. After surgery the main thoracic Cobb angle becomes 83 degrees and lumbar Cobb angle becomes 40 degrees, with 5 days length of stay and less than 800 mL blood loss during surgery. There is no complaint at two months after surgery; he has already come back to normal activity with good functional activity. PMID:27064801

  8. External manipulation of nanostructure in photoresponsive lipid depot matrix to control and predict drug release in vivo.

    PubMed

    Fong, Wye-Khay; Hanley, Tracey L; Thierry, Benjamin; Hawley, Adrian; Boyd, Ben J; Landersdorfer, Cornelia B

    2016-04-28

    On-demand drug delivery systems are highly promising to control the time-course of drug release and ultimately optimize drug concentration time profiles in patients. Lipid based lyotropic liquid crystalline mesophases have demonstrated exceptional responsiveness to external stimuli such as heat, pH and light. Our objective was to quantitatively characterize the time-course of light activated drug release from near infrared (NIR) activated photothermal systems using ex vivo and in vivo studies. Photoresponsive hybrid gold nanorod-liquid crystalline matrices were prepared and loaded into custom-made implants which were inserted into subcutaneous tissues in rats. Time resolved SAXS studies showed the abdomen to be the best site of implantation to achieve in vivo activation of the subcutaneous dose from by the NIR laser. External control of drug release was achieved via NIR laser light and plasma concentrations of the model drug were determined over time. Laser activation achieved a phase change of the photoresponsive formulations and thereby a considerable change in the rate of drug release. Population pharmacokinetic modeling of all results simultaneously revealed a two stage release process unique to these liquid crystalline matrices. The developed structural model was able to successfully describe also the results of our previous study in 2009 where a change in temperature was utilized to trigger subcutaneous drug release. Thus, modeling of the data proved to be a valuable analytical tool which provided a quantitative understanding of the time-course of drug release in vivo and will be essential in the development of these matrices as on-demand release systems. PMID:26924351

  9. Can Chemical Mouthwash Agents Achieve Plaque/Gingivitis Control?

    PubMed

    Van der Weijden, Fridus A; Van der Sluijs, Eveline; Ciancio, Sebastian G; Slot, Dagmar E

    2015-10-01

    Also note that structured abstracts are not allowed per journal style: What is the effect of a mouthwash containing various active chemical ingredients on plaque control and managing gingivitis in adults based on evidence gathered from existing systematic reviews? The summarized evidence suggests that mouthwashes containing chlorhexidine(CHX) and essential oils (EO) had a large effect supported by a strong body of evidence. Also there was strong evidence for a moderate effect of cetylpyridinium chloride(CPC). Evidence suggests that a CHX mouthwash is the first choice, the most reliable alternative is EO. No difference between CHX and EO with respect to gingivitis was observed. PMID:26427569

  10. A new TGF-β3 controlled-released chitosan scaffold for tissue engineering synovial sheath.

    PubMed

    Jiang, Ke; Wang, Ziming; Du, Quanyin; Yu, Jiang; Wang, Aimin; Xiong, Yan

    2014-03-01

    The post-operative outcome of flexor tendon healing remains limited by flexor tendon adhesion that reduces joint range of motion. Despite improvement in different methods, peritendinous adhesion formation continues to present a formidable challenge. Recent studies showed that transforming growth factor-β3 (TGF-β3) may be the key factor to reducing adhesion formation in skin or tendon. In this study, we designed a novel type of tissue engineering synovial sheath containing TGF-β3, to prevent flexor tendon adhesion. First, to achieve a stable release of TGF-β3, chitosan microspheres, prepared by crosslinking-emulsion, were used for the delivery of TGF-β3. Second, a three-dimensional chitosan scaffold was prepared by lyophilization, and TGF-β3 microspheres were carefully introduced into the scaffold. Then, synovial cells were cultured and then seeded into the TGF-β3 loaded scaffold to produce TGF-β3 controlled-released tissue engineering synovial sheath. Tests clearly demonstrated that the scaffold has good structure and compatibility with cells. These results expand the feasibility of combinative strategies of controlled protein release and tissue-engineered synovial sheath formation. Application of this scaffold to tendon repair sites may help to prevent adhesion of tendon healing. PMID:23564463

  11. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight disease of apple.

    PubMed

    Kim, In-Yong; Pusey, Paul Lawrence; Zhao, Youfu; Korban, Schuyler S; Choi, Hyungsoo; Kim, Kyekyoon Kevin

    2012-07-10

    Microencapsulation and controlled release of the biocontrol agent Pantoea agglomerans strain E325 (E325), an antagonist to the bacterial plant pathogen Erwinia amylovora that causes fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 μm in diameter, were fabricated to encapsulate E325 within the core, along with nutrients, to preserve viability and promote proliferation. Controlled release of E325 was achieved by separately adjusting alginate concentrations in the shell and core solutions, and by modifying the AMC size. Viability of E325 was monitored via fluorescent staining, revealing either lack of or minimal stress during or after encapsulation. Proliferation of E325 within AMCs, followed by their subsequent release, and colonization activities within confines of apple flowers were studied under different encapsulation conditions using rfp-labeled E325 to obtain highly promising results. This study provided a 'proof of concept' of the successful use of a microencapsulated biocontrol agent, E325, against E. amylovora, and could serve as a model for further studies on the development of effective plant disease management strategies. PMID:22516094

  12. Radio controlled release apparatus for animal data acquisition devices

    DOEpatents

    Stamps, James Frederick

    2000-01-01

    A novel apparatus for reliably and selectively releasing a data acquisition package from an animal for recovery. The data package comprises two parts: 1) an animal data acquisition device and 2) a co-located release apparatus. One embodiment, which is useful for land animals, the release apparatus includes two major components: 1) an electronics package, comprising a receiver; a decoder comparator, having at plurality of individually selectable codes; and an actuator circuit and 2) a release device, which can be a mechanical device, which acts to release the data package from the animal. To release a data package from a particular animal, a radio transmitter sends a coded signal which is decoded to determine if the code is valid for that animal data package. Having received a valid code, the release device is activated to release the data package from the animal for subsequent recovery. A second embodiment includes floatation means and is useful for releasing animal data acquisition devices attached to sea animals. This embodiment further provides for releasing a data package underwater by employing an acoustic signal.

  13. Achievements in and Challenges of Tuberculosis Control in South Korea

    PubMed Central

    Kim, Ji Han

    2015-01-01

    After the Korean War (1950–1953), nearly 6.5% of South Korea’s population had active tuberculosis (TB). In response, South Korea implemented the National Tuberculosis Program in 1962. From 1965 to 1995, the prevalence of bacteriologically confirmed pulmonary TB in South Korea decreased from 940 to 219 cases per 100,000 population. Astounding economic growth might have contributed to this result; however, TB incidence in South Korea remains the highest among high-income countries. The rate of decrease in TB incidence seems to have slowed over the past 15 years. A demographic shift toward an older population, many of whom have latent TB and various concurrent conditions, is challenging TB control efforts in South Korea. The increasing number of immigrants also plays a part in the prolonged battle against TB. A historical review of TB in South Korea provides an opportunity to understand national TB control efforts that are applicable to other parts of the world. PMID:26485188

  14. Muscle function in avian flight: achieving power and control

    PubMed Central

    Biewener, Andrew A.

    2011-01-01

    Flapping flight places strenuous requirements on the physiological performance of an animal. Bird flight muscles, particularly at smaller body sizes, generally contract at high frequencies and do substantial work in order to produce the aerodynamic power needed to support the animal's weight in the air and to overcome drag. This is in contrast to terrestrial locomotion, which offers mechanisms for minimizing energy losses associated with body movement combined with elastic energy savings to reduce the skeletal muscles' work requirements. Muscles also produce substantial power during swimming, but this is mainly to overcome body drag rather than to support the animal's weight. Here, I review the function and architecture of key flight muscles related to how these muscles contribute to producing the power required for flapping flight, how the muscles are recruited to control wing motion and how they are used in manoeuvring. An emergent property of the primary flight muscles, consistent with their need to produce considerable work by moving the wings through large excursions during each wing stroke, is that the pectoralis and supracoracoideus muscles shorten over a large fraction of their resting fibre length (33–42%). Both muscles are activated while being lengthened or undergoing nearly isometric force development, enhancing the work they perform during subsequent shortening. Two smaller muscles, the triceps and biceps, operate over a smaller range of contractile strains (12–23%), reflecting their role in controlling wing shape through elbow flexion and extension. Remarkably, pigeons adjust their wing stroke plane mainly via changes in whole-body pitch during take-off and landing, relative to level flight, allowing their wing muscles to operate with little change in activation timing, strain magnitude and pattern. PMID:21502121

  15. A Simple Approach for Molecular Controlled Release based on Atomic Layer Deposition Hybridized Organic-Inorganic Layers

    NASA Astrophysics Data System (ADS)

    Boehler, Christian; Güder, Firat; Kücükbayrak, Umut M.; Zacharias, Margit; Asplund, Maria

    2016-01-01

    On-demand release of bioactive substances with high spatial and temporal control offers ground-breaking possibilities in the field of life sciences. However, available strategies for developing such release systems lack the possibility of combining efficient control over release with adequate storage capability in a reasonably compact system. In this study we present a new approach to target this deficiency by the introduction of a hybrid material. This organic-inorganic material was fabricated by atomic layer deposition of ZnO into thin films of polyethylene glycol, forming the carrier matrix for the substance to be released. Sub-surface growth mechanisms during this process converted the liquid polymer into a solid, yet water-soluble, phase. This layer permits extended storage for various substances within a single film of only a few micrometers in thickness, and hence demands minimal space and complexity. Improved control over release of the model substance Fluorescein was achieved by coating the hybrid material with a conducting polymer film. Single dosage and repetitive dispensing from this system was demonstrated. Release was controlled by applying a bias potential of ±0.5 V to the polymer film enabling or respectively suppressing the expulsion of the model drug. In vitro tests showed excellent biocompatibility of the presented system.

  16. A Simple Approach for Molecular Controlled Release based on Atomic Layer Deposition Hybridized Organic-Inorganic Layers

    PubMed Central

    Boehler, Christian; Güder, Firat; Kücükbayrak, Umut M.; Zacharias, Margit; Asplund, Maria

    2016-01-01

    On-demand release of bioactive substances with high spatial and temporal control offers ground-breaking possibilities in the field of life sciences. However, available strategies for developing such release systems lack the possibility of combining efficient control over release with adequate storage capability in a reasonably compact system. In this study we present a new approach to target this deficiency by the introduction of a hybrid material. This organic-inorganic material was fabricated by atomic layer deposition of ZnO into thin films of polyethylene glycol, forming the carrier matrix for the substance to be released. Sub-surface growth mechanisms during this process converted the liquid polymer into a solid, yet water-soluble, phase. This layer permits extended storage for various substances within a single film of only a few micrometers in thickness, and hence demands minimal space and complexity. Improved control over release of the model substance Fluorescein was achieved by coating the hybrid material with a conducting polymer film. Single dosage and repetitive dispensing from this system was demonstrated. Release was controlled by applying a bias potential of ±0.5 V to the polymer film enabling or respectively suppressing the expulsion of the model drug. In vitro tests showed excellent biocompatibility of the presented system. PMID:26791399

  17. A Simple Approach for Molecular Controlled Release based on Atomic Layer Deposition Hybridized Organic-Inorganic Layers.

    PubMed

    Boehler, Christian; Güder, Firat; Kücükbayrak, Umut M; Zacharias, Margit; Asplund, Maria

    2016-01-01

    On-demand release of bioactive substances with high spatial and temporal control offers ground-breaking possibilities in the field of life sciences. However, available strategies for developing such release systems lack the possibility of combining efficient control over release with adequate storage capability in a reasonably compact system. In this study we present a new approach to target this deficiency by the introduction of a hybrid material. This organic-inorganic material was fabricated by atomic layer deposition of ZnO into thin films of polyethylene glycol, forming the carrier matrix for the substance to be released. Sub-surface growth mechanisms during this process converted the liquid polymer into a solid, yet water-soluble, phase. This layer permits extended storage for various substances within a single film of only a few micrometers in thickness, and hence demands minimal space and complexity. Improved control over release of the model substance Fluorescein was achieved by coating the hybrid material with a conducting polymer film. Single dosage and repetitive dispensing from this system was demonstrated. Release was controlled by applying a bias potential of ± 0.5 V to the polymer film enabling or respectively suppressing the expulsion of the model drug. In vitro tests showed excellent biocompatibility of the presented system. PMID:26791399

  18. Design of Controlled Release PLGA Microspheres for Hydrophobic Fenretinide.

    PubMed

    Zhang, Ying; Wischke, Christian; Mittal, Sachin; Mitra, Amitava; Schwendeman, Steven P

    2016-08-01

    Fenretinide, a chemotherapeutic agent for cancer, is water-insoluble and has a very low oral bioavailability. Hence, the objective was to deliver it as an injectable depot and improve the drug solubility and release behavior from poly(lactide-co-glycolide) (PLGA) microspheres by incorporating nonionic surfactants with fenretinide. Enhancement of drug solubilization was observed with Brij 35 or 98, Tween 20, and Pluronic F127, but not Pluronic F68. Co-incorporation of Brij 98 with fenretinide significantly changed the microsphere morphology and improved the fenretinide release profile. The most optimal microsphere formulation, with 20% Brij 98 as excipient, showed an initial in vitro burst around 20% and a sustained release over 28 days in a solubilizing release medium at 37 °C. The effect of addition of MgCO3, drug loading, and polymer blending on the release of fenretinide from PLGA microspheres was also investigated and observed to enhance the drug release. Two sustained release formulations, one incorporating 20% Brij 98 and the other incorporating 3% MgCO3 in the oil phase, were selected for dosing in Sprague-Dawley rats and compared to a single injection of an equivalent dose of fenretinide drug suspension. These two formulations were chosen due to their high encapsulation efficiency, high cumulative release, and desirable in vitro release profile. The drug suspension resulted in a higher initial release in rats compared to the polymeric formulations, however, sustained release was also observed beyond 2 weeks, which may be attributed to the physiological disposition of the drug in vivo. The two PLGA based test formulations provided the desired low initial burst of fenretinide followed by 4 weeks of in vivo sustained release. PMID:27144450

  19. Development of controlled release spheroids using natural polysaccharide as release modifier.

    PubMed

    Kulkarni, Giriraj T; Gowthamarajan, K; Dhobe, Rohan R; Yohanan, Fenni; Suresh, B

    2005-01-01

    A polysaccharide hydrogel was isolated from the seeds of Tamarindus indica (tamarind) and was used as release modifier for the preparation of diclofenac sodium spheroids, using extrusion-spheronization technique. The process was studied for the effect of variables to arrive at spheroids with satisfactory particle shape, size and size-distribution. The prepared spheroids were characterized for surface morphology, qualitative surface porosity, friability, bulk density, and flow properties. The in vitro release studies exhibited a zero-order release kinetics that was confirmed by Higuchi's and Peppas' models. A credible correlation was obtained among swelling index, viscosity, surface roughness of the polysaccharide, and in vitro dissolution profile of the spheroids. In the comparative bioavailability study, we found that the developed spheroids were able to sustain the drug release over 8 hr and could improve the extent of absorption and bioavailability of the drug. PMID:16036714

  20. Control of arachidonic acid release in chick muscle cultures

    NASA Technical Reports Server (NTRS)

    Templeton, G. H.; Padalino, M.; Wright, W.

    1985-01-01

    Cultures from thigh muscles of 12 day old embryonic chicks are utilized to examine arachidonic release, prostaglandin (PG) biosynthesis, and protein synthesis. The preparation of the cultures is described. It is observed that exogenous arachidonic acid is formed into photsphatidylethanolamine and phosphatidylcholine, is released by a calcium ionosphere or phospholiphase simulator, and is the substrate for the biosynthesis of PG; the epidermal growth factor and PGF do not stimulate protein synthesis over the basal levels. The relationship between arachidonate release and melittin is studied. The data reveal that a change in intracellular calcium stimulates phospholiphase activity, arachidonate release, and PG synthesis in chick muscle culture.

  1. Determination of Nitrogen, Phosphorus, and Potassium Release Rates of Slow- and Controlled-Release Fertilizers: Single-Laboratory Validation, First Action 2015.15.

    PubMed

    Thiex, Nancy

    2016-01-01

    A previously validated method for the determination of nitrogen release patterns of slow- and controlled-release fertilizers (SRFs and CRFs, respectively) was submitted to the Expert Review Panel (ERP) for Fertilizers for consideration of First Action Official Method(SM) status. The ERP evaluated the single-laboratory validation results and recommended the method for First Action Official Method status and provided recommendations for achieving Final Action. The 180 day soil incubation-column leaching technique was demonstrated to be a robust and reliable method for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and the results were only slightly affected by variations in environmental factors such as microbial activity, soil moisture, temperature, and texture. The release of P and K were also studied, but at fewer replications than for N. Optimization experiments on the accelerated 74 h extraction method indicated that temperature was the only factor found to substantially influence nutrient-release rates from the materials studied, and an optimized extraction profile was established as follows: 2 h at 25°C, 2 h at 50°C, 20 h at 55°C, and 50 h at 60°C. PMID:26987312

  2. Children's effortful control and academic achievement: do relational peer victimization and classroom participation operate as mediators?

    PubMed

    Valiente, Carlos; Swanson, Jodi; Lemery-Chalfant, Kathryn; Berger, Rebecca H

    2014-08-01

    Given that early academic achievement is related to numerous developmental outcomes, understanding processes that promote early success in school is important. This study was designed to clarify how students' (N=291; M age in fall of kindergarten=5.66 years, SD=0.39 year) effortful control, relational peer victimization, and classroom participation relate to achievement, as students progress from kindergarten to first grade. Effortful control and achievement were assessed in kindergarten, classroom participation and relational peer victimization were assessed in the fall of first grade, and achievement was reassessed in the spring of first grade. Classroom participation, but not relational peer victimization, mediated relations between effortful control and first grade standardized and teacher-rated achievement, controlling for kindergarten achievement. Findings suggest that aspects of classroom participation, such as the ability to work independently, may be useful targets of intervention for enhancing academic achievement in young children. PMID:25107413

  3. Controlled Release of Collagen-Binding SDF-1α Improves Cardiac Function after Myocardial Infarction by Recruiting Endogenous Stem Cells

    PubMed Central

    Sun, Jie; Zhao, Yannan; Li, Qingguo; Chen, Bing; Hou, Xianglin; Xiao, Zhifeng; Dai, Jianwu

    2016-01-01

    Stromal cell-derived factor-1α (SDF-1α) is a well-characterized chemokine that mobilizes stem cells homing to the ischemic heart, which is beneficial for cardiac regeneration. However, clinically administered native SDF-1α diffuses quickly, thus decreasing its local concentration, and results in side effects. Thus, a controlled release system for SDF-1α is required to produce an effective local concentration in the ischemic heart. In this study, we developed a recombinant chemokine, consisting of SDF-1α and a collagen-binding domain, which retains both the SDF-1α and collagen-binding activity (CBD-SDF-1α). In an in vitro assay, CBD-SDF-1α could specifically bind to a collagen gel and achieve sustained release. An intramyocardial injection of CBD-SDF-1α after acute myocardial infarction demonstrated that the protein was largely tethered in the ischemic area and that controlled release had been achieved. Furthermore, CBD-SDF-1α enhanced the recruitment of c-kit positive (c-kit+) stem cells, increased capillary density and improved cardiac function, whereas NAT-SDF-1α had no such beneficial effects. Our findings demonstrate that CBD-SDF-1α can specifically bind to collagen and achieve controlled release both in vitro and in vivo. Local delivery of this protein could mobilize endogenous stem cells homing to the ischemic heart and improve cardiac function after myocardial infarction. PMID:27226084

  4. Encapsulation and characterization of controlled release flurbiprofen loaded microspheres using beeswax as an encapsulating agent.

    PubMed

    Ranjha, Nazar M; Khan, Hafeezullah; Naseem, Shahzad

    2010-05-01

    The aim of the present study was to extend the use of flurbiprofen in clinical settings by avoiding its harmful gastric effects. For this purpose, we designed the controlled release solid lipid flurbiprofen microspheres (SLFM) by emulsion congealing technique. Drug was entrapped into gastro resistant biodegradable beeswax microspheres which were prepared at different drug/beeswax ratios 1:1, 1:2 and 1:3 using gelatin and tween 20 as emulsifying agents. The effect of emulsifiers and the effect drug/beeswax ratios were studied on hydration rate, encapsulating efficiency, micromeritic properties, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (X-RD) analysis and in vitro drug release at pH 1.2 for 2 h and at pH 6.8 for 10 h. SEM revealed that microspheres made with tween 20 were smooth while microspheres made with gelatin showed porous morphology, however, they were all spherical in nature. The practical yield (recovery) showed a dependence on drug-beeswax ratio and it was variable from 53 to 84%. High loading encapsulating efficiency of flurbiprofen from 8 to 94% was achieved. FTIR and DSC analysis confirmed the absence of any drug polymer interaction indicating drug stability during microencapsulation. X-RD of pure flurbiprofen shows sharp peaks, which decreases on encapsulation, indicating decrease in the crystallinity of drug in microspheres. The micromeritic studies confirmed the presence of excellent and good flow properties of microspheres. Entrapment efficiency, morphology, practical yield, hydration rate, flow properties demonstrated their dependence on the HLB value of emulsifiers and emulsifiers with higher HLB were found more appropriate for effective microencapsulation of flurbiprofen. The release kinetics followed zero order mechanism of drug release at pH 6.8. Release pattern depends on the morphology of flurbiprofen microspheres and amount of beeswax used in

  5. Integrated Luminal and Cytosolic Aspects of the Calcium Release Control

    PubMed Central

    Baran, Irina

    2003-01-01

    We propose here a unitary approach to the luminal and cytosolic control of calcium release. A minimal number of model elements that realistically describe different data sets are combined and adapted to correctly respond to various physiological constraints. We couple the kinetic properties of the inositol 1,4,5 trisphosphate receptor/calcium channel with the dynamics of Ca2+ and K+ in both the lumen and cytosol, and by using a detailed simulation approach, we propose that local (on a radial distance ∼2 μm) calcium oscillations in permeabilized cells are driven by the slow inactivation of channels organized in discrete clusters composed of between six and 15 channels. Moreover, the character of these oscillations is found to be extremely sensitive to K+, so that the cytosolic and luminal calcium variations are in or out of phase if the store at equilibrium has tens or hundreds μM Ca2+, respectively, depending on the K+ gradient across the reticulum membrane. Different patterns of calcium signals can be reproduced through variation of only a few parameters. PMID:12609854

  6. Remotely Triggered Scaffolds for Controlled Release of Pharmaceuticals

    PubMed Central

    Roach, Paul; McGarvey, David J.; Lees, Martin R.; Hoskins, Clare

    2013-01-01

    Fe3O4-Au hybrid nanoparticles (HNPs) have shown increasing potential for biomedical applications such as image guided stimuli responsive drug delivery. Incorporation of the unique properties of HNPs into thermally responsive scaffolds holds great potential for future biomedical applications. Here we successfully fabricated smart scaffolds based on thermo-responsive poly(N-isopropylacrylamide) (pNiPAM). Nanoparticles providing localized trigger of heating when irradiated with a short laser burst were found to give rise to remote control of bulk polymer shrinkage. Gold-coated iron oxide nanoparticles were synthesized using wet chemical precipitation methods followed by electrochemical coating. After subsequent functionalization of particles with allyl methyl sulfide, mercaptodecane, cysteamine and poly(ethylene glycol) thiol to enhance stability, detailed biological safety was determined using live/dead staining and cell membrane integrity studies through lactate dehydrogenase (LDH) quantification. The PEG coated HNPs did not show significant cytotoxic effect or adverse cellular response on exposure to 7F2 cells (p < 0.05) and were carried forward for scaffold incorporation. The pNiPAM-HNP composite scaffolds were investigated for their potential as thermally triggered systems using a Q-switched Nd:YAG laser. These studies show that incorporation of HNPs resulted in scaffold deformation after very short irradiation times (seconds) due to internal structural heating. Our data highlights the potential of these hybrid-scaffold constructs for exploitation in drug delivery, using methylene blue as a model drug being released during remote structural change of the scaffold. PMID:23603890

  7. Why achievement motivation predicts success in business but failure in politics: the importance of personal control.

    PubMed

    Winter, David G

    2010-12-01

    Several decades of research have established that implicit achievement motivation (n Achievement) is associated with success in business, particularly in entrepreneurial or sales roles. However, several political psychology studies have shown that achievement motivation is not associated with success in politics; rather, implicit power motivation often predicts political success. Having versus lacking control may be a key difference between business and politics. Case studies suggest that achievement-motivated U.S. presidents and other world leaders often become frustrated and thereby fail because of lack of control, whereas power-motivated presidents develop ways to work with this inherent feature of politics. A reevaluation of previous research suggests that, in fact, relationships between achievement motivation and business success only occur when control is high. The theme of control is also prominent in the development of achievement motivation. Cross-national data are also consistent with this analysis: In democratic industrialized countries, national levels of achievement motivation are associated with strong executive control. In countries with low opportunity for education (thus fewer opportunities to develop a sense of personal control), achievement motivation is associated with internal violence. Many of these manifestations of frustrated achievement motivation in politics resemble authoritarianism. This conclusion is tested by data from a longitudinal study of 113 male college students, showing that high initial achievement motivation combined with frustrated desires for control is related to increases in authoritarianism (F-scale scores) during the college years. Implications for the psychology of leadership and practical politics are discussed. PMID:21039527

  8. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    NASA Astrophysics Data System (ADS)

    Valenti, G.; La Carta, S.; Mazzotti, G.; Rapisarda, M.; Perna, S.; Di Gesù, R.; Giorgini, L.; Carbone, D.; Recca, G.; Rizzarelli, P.

    2016-05-01

    models allowed to deduce that release of BDP is controlled over time from PMMA-b-PHEMA 53/47. In particular, PMMA-b-PHEMA 53/47 showed the best release profile to achieve the therapeutic reference dose of 3 µg/die, employed in treatment of posterior eye disease, up to four months. Accordingly, PMMA-b-PHEMA 53/47 has been tested to prepare ocular inserts. Ocular inserts with different shape and the same area of polymer films have been obtained using silicon moulds made by a 3D printer.

  9. Core-in-cup tablet design of metoprolol succinate and its evaluation for controlled release.

    PubMed

    Nagaraju, Ravouru; Meera, Durgumahanthi Sai; Kaza, Rajesh; Arvind, Vakati Venkata; Venkateswarlu, Vobalaboina

    2009-12-01

    The core-in-cup matrix tablets of Metoprolol succinate were prepared by wet granulation technique. Of all the investigated formulations, the optimized formulation of MS-09 followed zero-order kinetics of drug release. Trail on MS-09 was formulated using 7.5% hydrogenated castor-oil (HCO) and 4% of hydroxyl propyl methylcellulose (HPMC K15M) with an objective to achieve a linear release profile for 24 h. There is no initial burst release, with 16.17% of drug released during the first hour and release was extended up to 24 hrs. Study of drug release kinetics was performed by application of dissolution data to various kinetic equations like zero-order; first order, Higuchi and Korsmeyer-Peppas, from R(2) value (0.9975) it was concluded that the drug release followed zero order kinetics with both erosion and diffusion as the release mechanisms. PMID:20025598

  10. [Rate of controlled-release urea pervasion through membrane determined by ultraviolet spectrophotometry].

    PubMed

    Zuo, Xiu-jin; Wang, Zhen-xin; Dai, Xiao-min; Zhou, Yi; Ma, Xiao-jun

    2006-06-01

    Application of controlled-release nitrogenous fertilizers can improve the efficiency of fertilizers and reduce the environmental pollution. Controlled-release urea (coated urea) is one of the controlled-release nitrogenous fertilizers developed quickly in the recent years. The rate of controlled-release urea pervasion through membrane is the most important index of the capacity of controlled release. There is a maximum absorption at lambda=426 nm with complex in acidic solution, using p-dimethylaminozenzaldehyde as color reagent, and the absorbance exhibits a linear reponses to the urea concentration over the range of 7.5-210 microg x mL(-1). The method for determining the rate of controlled-release urea pervasion through membrane was realized through determining the content of urea in the liquor, the recovery efficiency of the method is 96.1%-103.9%. PMID:16961255

  11. Analysis of the release process of phenylpropanolamine hydrochloride from ethylcellulose matrix granules IV.(1)) Evaluation of the controlled release properties for in vivo and in vitro release systems.

    PubMed

    Fukui, Atsuko; Fujii, Ryuta; Yonezawa, Yorinobu; Sunada, Hisakazu

    2007-11-01

    In the pharmaceutical preparation of a controlled release drug, it is very important and necessary to understand the release properties. The dissolution test is a very important and useful method for understanding and predicting drug-release properties. It was readily confirmed in the previous paper that the release process could be assessed quantitatively by a combination of the square-root time law and cube-root law equations for ethylcellulose (EC) matrix granules of phenylpropanolamine hydrochloride (PPA). In this paper EC layered granules were used in addition to EC matrix. The relationship between release property and the concentration of PPA in plasma after administration using beagle dogs were examined. Then it was confirmed that the correlativity for EC layered granules and EC matrix were similar each other. Therefore, it was considered that the dissolution test is useful for prediction of changes in concentration of PPA in the blood with time. And it was suggested that EC layered granules were suitable as a controlled release system as well as EC matrix. PMID:17978513

  12. Controlled release of metformin hydrochloride and repaglinide from sandwiched osmotic pump tablet.

    PubMed

    Qin, Chao; He, Wei; Zhu, Chunli; Wu, Mengmeng; Jin, Zhu; Zhang, Qiang; Wang, Guangji; Yin, Lifang

    2014-05-15

    The marketed compound tablet of metformin hydrochloride (MH) and repaglinide (RG) exhibits perfect multidrug therapeutic effect of type 2 diabetes. However, due to the short half life of the drugs, the tablet has to be administered 2 to 3 times a day, causing inconvenience to patient and fluctuations of plasma concentration. Here, a sandwiched osmotic pump tablet was developed to deliver the two drugs simultaneously at zero-order rate, in which MH and RG were loaded in different layers separated by a push layer. The osmotic pump tablet was prepared by a combination of three tableting procedure and film coating method. The factors including type and amount of propellant, osmotic active agents, amount of porogenic agent, coating weight, orifice diameter were optimized. The pharmacokinetic study was performed in beagle dogs, and the drug concentration in plasma samples was assayed by HPLC-MS/MS method. Simultaneous, controlled release of MH and RG in the first 12 and 8h was achieved from the optimized formulation. A significantly decreased Cmax, prolonged Tmax and satisfactory bioavailability of the osmotic pump tablet were obtained, and a good in vivo-in vitro correlation of the two drugs was also established. In summary, the sandwiched osmotic pump tablet released the MH and RG simultaneously at zero-order rate, and exhibited significant sustained release effect in vivo and good in vivo-in vitro correlation. The designed controlled release system for MH and RG proposed a promising replacement for the marked compound product in the therapy of type 2 diabetes. PMID:24607209

  13. Materials for Pharmaceutical Dosage Forms: Molecular Pharmaceutics and Controlled Release Drug Delivery Aspects

    PubMed Central

    Mansour, Heidi M.; Sohn, MinJi; Al-Ghananeem, Abeer; DeLuca, Patrick P.

    2010-01-01

    Controlled release delivery is available for many routes of administration and offers many advantages (as microparticles and nanoparticles) over immediate release delivery. These advantages include reduced dosing frequency, better therapeutic control, fewer side effects, and, consequently, these dosage forms are well accepted by patients. Advances in polymer material science, particle engineering design, manufacture, and nanotechnology have led the way to the introduction of several marketed controlled release products and several more are in pre-clinical and clinical development. PMID:20957095

  14. Design and evaluation of mucoadhesive beads of glipizide as a controlled release drug delivery system.

    PubMed

    Bera, K; Khanam, J; Mohanraj, K P; Mazumder, B

    2014-01-01

    The present work aims at the development of a low-cost controlled release system of glipizide beads embedded in pectin to overcome the problem of frequent dosing of drug. The method of preparation has been optimised by experimental design to achieve satisfactory responses with respect to controlling variables. The controlling variables are X1, drug-polymer ratio; X2, surfactant concentration and X3, isooctane-acetone ratio. The most effective combination is X1(1:6), X2(1%), X3(50:50). Various parameters such as mucoadhesivity and swellability of beads, characterisation, dissolution, stability, ex vivo absorption and in vivo (Oral glucose tolerance test in rat) studies were performed with the optimised product. The optimised product was found quiet satisfactory that showed yield of 86.78%, drug entrapment efficiency (DEE) of 87.38% and drug release was extended up to 18 h. The present formulation of glipizide is a promising multiparticulate system of glipizide with significant hypoglycemic effect, and moreover it was prepared rapidly with ease. PMID:24047213

  15. Controlled release system for ametryn using polymer microspheres: preparation, characterization and release kinetics in water.

    PubMed

    Grillo, Renato; Pereira, Anderson do Espirito Santo; de Melo, Nathalie Ferreira Silva; Porto, Raquel Martins; Feitosa, Leandro Oliveira; Tonello, Paulo Sergio; Dias Filho, Newton L; Rosa, André Henrique; Lima, Renata; Fraceto, Leonardo Fernandes

    2011-02-28

    The purpose of this work was to develop a modified release system for the herbicide ametryn by encapsulating the active substance in biodegradable polymer microparticles produced using the polymers poly(hydroxybutyrate) (PHB) or poly(hydroxybutyrate-valerate) (PHBV), in order to both improve the herbicidal action and reduce environmental toxicity. PHB or PHBV microparticles containing ametryn were prepared and the efficiencies of herbicide association and loading were evaluated, presenting similar values of approximately 40%. The microparticles were characterized by scanning electron microscopy (SEM), which showed that the average sizes of the PHB and PHBV microparticles were 5.92±0.74 μm and 5.63±0.68 μm, respectively. The ametryn release profile was modified when it was encapsulated in the microparticles, with slower and more sustained release compared to the release profile of pure ametryn. When ametryn was associated with the PHB and PHBV microparticles, the amount of herbicide released in the same period of time was significantly reduced, declining to 75% and 87%, respectively. For both types of microparticle (PHB and PHBV) the release of ametryn was by diffusion processes due to anomalous transport (governed by diffusion and relaxation of the polymer chains), which did not follow Fick's laws of diffusion. The results presented in this paper are promising, in view of the successful encapsulation of ametryn in PHB or PHBV polymer microparticles, and indications that this system may help reduce the impacts caused by the herbicide, making it an environmentally safer alternative. PMID:21215514

  16. Controlled-release NPK fertilizer encapsulated by polymeric membranes.

    PubMed

    Jarosiewicz, Anna; Tomaszewska, Maria

    2003-01-15

    The commercial granular fertilizer NPK6-20-30 was coated using polysulfone (PSF), polyacrylonitrile (PAN), and cellulose acetate (CA). The coatings were formed from the polymer solutions by the phase inversion technique. Measurements of the thickness and porosity of the prepared coatings and a microphotographic observation of the coatings were performed. The physical properties of the coatings influence the release rate of macronutrients which are present in the core of the coated fertilizer. In the case of PAN coating with 60.45% porosity, prepared from a 16% polymer solution, 100% of NH(4)(+) and P(2)O(5) was released after 4 h of test and 99.7% of K(+) after 5 h of test, whereas in the case of coating with 48.8% porosity, 31.8% of NH(4)(+), 16.7% of P(2)O(5), and 11.6% of K(+) was released after 5 h. In all experiments, different selectivities of the coatings in terms of the release of components were observed. The release of potassium through the coatings made of PSF and PAN was the slowest. The same tendency was observed for the release of nitrogen through a coating of CA. The release of fertilizer active components was the slowest in the case of PSF. The lowest porosity coating was prepared from the 18% PSF solution. PMID:12517104

  17. Smart magnetic poly(N-isopropylacrylamide) to control the release of bio-active molecules.

    PubMed

    Dionigi, Chiara; Lungaro, Lisa; Goranov, Vitaly; Riminucci, Alberto; Piñeiro-Redondo, Yolanda; Bañobre-López, Manuel; Rivas, José; Dediu, Valentin

    2014-10-01

    Thermo switchable magnetic hydrogels undoubtedly have a great potential for medical applications since they can behave as smart carriers able to transport bioactive molecules to a chosen part of the body and release them on demand via magneto-thermal activation. We report on the ability to modify the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM) on demand from 32 °C to LCST ≥ 37 °C. This was achieved by the absorption of controlled amounts of magnetite nanoparticles on the polymer chains. We show, through the effect on cell viability, that the resulting magnetic PNIPAM is able to trap and to release bio-active molecules, such as cell growth factors. The activities of the released bio molecule are tested on human umbilical vein endothelial cells culture. We demonstrate that the LCST of the magnetic PNIPAM can be reached remotely via inductive heating with an alternating magnetic field. This approach on magnetic PNIPAM clearly supports appealing applications in safe biomedicine. PMID:24477874

  18. Hollow polycaprolactone composite fibers for controlled magnetic responsive antifungal drug release.

    PubMed

    Wang, Baolin; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

    2016-09-01

    Hollow magnetic fibers for trigger based drug release were synthesized using one-step co-axial electrospinning (COX-ES). This was achieved by encapsulating the antifungal active 'ketoconazole' (KCZ) and iron oxide (Fe3O4) nanoparticles (NPs) in composite form within the core shell polymeric matrix material (polycaprolactone, PCL) during the COX-ES process. Dimethyl silicone oil was used as the inner core (liquid) of co-flowing solutions, which subsequently perfused out of the two-phase electrospun microstructures to form hollow fibers. Resulting drug-loaded magnetic hollow fibers were characterized using optical microscopy, scanning electron microscopy and Fourier Transform Infra-Red. The tensile strength and magnetization properties of composite fibers were also assessed. KCZ drug concentration in electrospinning solutions strongly influenced resulting fiber morphology, drug loading efficiency and release. Expedited drug release during a slow-sustained phase was demonstrated through the application of an auxiliary magnetic field. Variations in tensile strength (∼1.3-6.3MPa) were due to composite fiber components compromising polymer chain integrity. In-vitro cell studies (using human cervical carcinoma cell lines) demonstrated fiber biocompatibility. The present study demonstrates the potential application of magnetic hollow fibers for controlled treatment of fungal infections and antimicrobial indications. PMID:27295492

  19. Preparation of Polypyrrole-Protein Composite Films and the Electrochemically Controlled Release of Proteins.

    PubMed

    Jin, Juan; Huang, Zhongbing; Yin, Guangfu; Lin, Jiangli; Li, Qiuping; Han, Donghui

    2016-03-01

    It is fabricated that an electrically controlled release system based on the (poly-L-lactic acid)-mixed polypyrrole (PLLA-PPy) films through casting film of PPy and PLLA mixed solution on the glass plate, in which polyglutamic acid (PGlu)-doped PPy nanoparticles (NPs) with -50 nm diameter are synthesized via chemical oxidation. Surface conductivity of the composite film is (3.33 ± 2.01) x 10(-3) S/cm. Bovine serum albumin (BSA), as a model protein drug, is chemically linked onto the composite film via carbodiimide chemistry due to the good surface nano-structure of PLLA-PPy film. The releases of BSA from PLLA-PPy film under constant current and constant voltage can be achieved using the two-electrode electrochemical system. 6 h accumulative releases of BSA are 276 μg/cm2 and 176 μg/cm2 under 3 mA and 1 V electrical stimulation, respectively, accompanied with de-doping of PGlu and separation of a part of PPy NPs from the composite film. The results of cell experiment indicate that PGlu-doped PPy NPs in the prepared composite film have good cyto-compatibility. These results suggest that PPy-PLLA composite film would be able to be applied in the construction of degradable protein-drug-loaded scaffold for nerve tissue repair. PMID:27455630

  20. Use of natural and biobased materials for controlled-release of urea in water: Environmental applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urea pearls were encapsulated in cloisite-based matrices using different natural materials (lignin, beeswax and latex) to control the release of urea over time. It was found that all cloisite-based fertilizer tablets showed better release profiles than neat urea tablets. The best release profile was...

  1. Quantifying Winter Discharge of Controlled Release Fertilizers to Determine Environmental Impact and Plant Uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is widely believed in the nursery industry that controlled release fertilizers (CRF) release nutrients only when temperatures are greater than ˜4ºC (40ºF). Research recently conducted in Southern California reported CRF continue to release nitrate and phosphorus throughout the winter months. We...

  2. Genetic control of Aedes aegypti: data-driven modelling to assess the effect of releasing different life stages and the potential for long-term suppression

    PubMed Central

    2014-01-01

    Background Control of the world’s most important vector-borne viral disease, dengue, is a high priority. A lack of vaccines or effective vector control methods means that novel solutions to disease control are essential. The release of male insects carrying a dominant lethal (RIDL) is one such approach that could be employed to control Aedes aegypti. To maximise the potential of RIDL control, optimum release strategies for transgenic mosquitoes are needed. The use of field data to parameterise models allowing comparisons of the release of different life-stages is presented together with recommendations for effective long-term suppression of a wild Ae. aegypti population. Methods A compartmental, deterministic model was designed and fitted to data from large-scale pupal mark release recapture (MRR) field experiments to determine the dynamics of a pupal release. Pulsed releases of adults, pupae or a combination of the two were simulated. The relative ability of different release methods to suppress a simulated wild population was examined and methods to maintain long-term suppression of a population explored. Results The pupal model produced a good fit to field data from pupal MRR experiments. Simulations using this model indicated that adult-only releases outperform pupal-only or combined releases when releases are frequent. When releases were less frequent pupal-only or combined releases were a more effective method of distributing the insects. The rate at which pupae eclose and emerge from release devices had a large influence on the relative efficacy of pupal releases. The combined release approach allows long-term suppression to be maintained with smaller low-frequency releases than adult- or pupal-only release methods. Conclusions Maximising the public health benefits of RIDL-based vector control will involve optimising all stages of the control programme. The release strategy can profoundly affect the outcome of a control effort. Adult-only, pupal-only and

  3. Relations among Peer Acceptance, Inhibitory Control, and Math Achievement in Early Adolescence

    ERIC Educational Resources Information Center

    Oberle, Eva; Schonert-Reichl, Kimberly A.

    2013-01-01

    This study examined relations among peer acceptance, inhibitory control, and math achievement in ninety-nine 4th and 5th grade early adolescents. Teachers rated students on peer acceptance and students completed a computerized executive function task assessing inhibitory control. Math achievement was assessed via end of year math grades. Results…

  4. Criterion-Related Validity of the Nowicki-Strickland Locus of Control Scale with Academic Achievement.

    ERIC Educational Resources Information Center

    Nunn, Gary D.; And Others

    1986-01-01

    Investigated the relationships between student locus of control and academic achievement in grades five through eight. The Nowicki-Strickland Locus of Control Scale (NSLOCS) was used to measure motivation, and the Iowa Tests of Basic Skills (ITBS) to assess academic achievement. Results indicated moderate inverse relationships between level of…

  5. In vivo response to biodegradable controlled antibiotic release systems.

    PubMed

    Korkusuz, F; Korkusuz, P; Ekşioĝlu, F; Gürsel, I; Hasirci, V

    2001-05-01

    In this study, the major goal was to evaluate in vitro and in vivo findings by macroscopy, radiology, and histology to determine the effectiveness of therapy of experimental implant-related osteomyelitis with antibiotic carrier rods constructed of microbial polyesters. The polymers used were poly(3-hydroxybutyrate-co-4-hydroxyvalerate) [P(3-HB-co-4-HB)] and poly(3-hydroxybutyrate-co-3-hydroxy- valerate) [P(3-HB-co-3-HV)]. Both the Sulperazone and the Duocid-P(3-HB-co-4-HB) rods with a drug to polymer ratio of 1:1 (w/w) were effective in treating the bone infection that was experimentally initiated by inoculation of a hemolytic strain of Staphylococcus aureus (coagulase positive; phage type 52/52b) together with metal implants into the medullary area of rabbit tibia. Macroscopical data revealed that the effectiveness of therapy was apparent at week 6 for all categories tested. Radiological findings with Duocid- and Sulperazone-loaded P(3-HB-co-4-HB) rods improved significantly when judged by changes in periosteal elevation, widening of bone shaft, new bone formation, and soft-tissue deformation after 6 weeks of implantation. Histologically the signs of infection were found to subside by weeks 3 and 6. Inflammatory cells were replaced with bone-forming cells upon treatment with Sulperazone-P(3-HB-co-4-HB) and Duocid-P(3-HB-co-4-HB). Osteoblastic activity was prominent. Intramedullary inflammation, although still present, started to be replaced by fibrous or bony tissue. Histological findings presented the subsidence of infection. In summary, the antibiotic-loaded biopolymeric rods appeared to have potential as a new controlled-release system for the treatment of implant related osteomyelitis and chronic osteomyelitis. PMID:11255173

  6. Moving the Achievement Goal Approach One Step Forward: Toward a Systematic Examination of the Autonomous and Controlled Reasons Underlying Achievement Goals

    ERIC Educational Resources Information Center

    Vansteenkiste, Maarten; Lens, Willy; Elliot, Andrew J.; Soenens, Bart; Mouratidis, Athanasios

    2014-01-01

    An important recent development in the achievement goal literature is to define achievement goals strictly as aims. In this overview, we argue that this restrictive definition of achievement goals paves the way for a systematic consideration of the autonomous and controlled reasons underlying individuals' achievement goals, a distinction…

  7. Presynaptic control of dopamine release by BETA-phenylethylamine

    SciTech Connect

    Zharikova, A.D.; Godukhin, O.V.

    1985-04-01

    The authors study the effect of extracellular ions (Ca/sup 2 +/, Na/sup 2 +/) on the beta-phenylethylamine (beta-PEA) releasing effect, dependence of this effect on the membrane potential of dopaminergic endings, and the participation of dopamine presynaptic autoreceptors in the realization of the effects of beta-PEA on dopamine (DA) release. Experi ments were carried out on noninbred male albino rats. By means of a microsyringe, (/sup 3/H)-DA hydrochloride was injected. The significance of the difference in levels of (/sup 3/H)-DA release during analogous periods of perfusion in the groups of animals compared was estimated by Student's test. These experiments in vivo thus demonstrated the ability of beta-PEA to regulate DA release in different directions depending on the functional state of the dopaminergic neuron.

  8. PHYSICAL AND CHEMICAL CONTROL OF RELEASED MICROORGANISMS AT FIELD SITES

    EPA Science Inventory

    An important consideration in the environmental release of a genetically engineered microorganism (GEM) is the capability for reduction or elimination of GEM populations once their function is completed or if adverse environmental effects are observed. In this study the decontami...

  9. Controlled release of donepezil intercalated in smectite clays.

    PubMed

    Park, Jin Kuen; Choy, Young Bin; Oh, Jae-Min; Kim, Ju Young; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-07-01

    The inorganic-organic hybrid for a drug delivery system was successfully realized by intercalating donepezil molecules into smectite clays (laponite XLG, saponite, and montmorillonite). According to the powder XRD patterns, TG profiles, and FT-IR spectra, it was confirmed that donepezil molecules were well stabilized in the interlayer space of clay via mono or double layer stacking. The adsorption amount and molecular structure of donepezil appeared to depend on the cation exchange capacity of the clay, which in turn, tailored the drug release patterns. Especially in the presence of a bulky cationic polymer (Eudragit E-100) in the release media, the release rate was found to be improved due to its effective replacement with intercalated donepezil molecules. Therefore, to formulate a complete drug delivery system, the hybrids were coated with Eudragit E-100 using a spray dryer, which also showed great enhancement in the release rate during a short period of time (180min). PMID:18502063

  10. Development and in vitro evaluation of oral controlled release formulations of celecoxib using optimization techniques.

    PubMed

    Chandran, Sajeev; Ravi, Punnarao; Saha, Ranendra N

    2006-07-01

    The objective of this study was to develop controlled release matrix embedded formulations of celecoxib (CCX) as candidate drug using hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC), either alone or in combination, using optimization techniques like polynomial method and composite design. This would enable development of controlled release formulations with predictable and better release characteristics in lesser number of trials. Controlled release matrix tablets of CCX were prepared by wet granulation method. The in vitro release rate studies were carried out in USP dissolution apparatus (paddle method) in 900 ml of sodium phosphate buffer (pH 7.4) with 1% v/v tween-80. The in vitro drug release data was suitably transformed and used to develop mathematical models using first order polynomial equation and composite design techniques of optimization. In the formulations prepared using HPMC alone, the release rate decreased as the polymer proportion in the matrix base was increased. Whereas in case of formulations prepared using EC alone, only marginal difference was observed in the release rate upon increasing the polymer proportion. In case of formulations containing combination of HPMC and EC, the release of the drug was found to be dependent on the relative proportions of HPMC and EC used in the tablet matrix. The release of the drug from these formulations was extended up to 21 h indicating they can serve as once daily controlled release formulations for CCX. Mathematical analysis of the release kinetics indicates a near approximate Fickian release character for most of the designed formulations. Mathematical equation developed by transforming the in vitro release data using composite design model showed better correlation between observed and predicted t(50%) (time required for 50% of the drug release) when compared to first order polynomial equation model. The equation thus developed can be used to predict the release characteristics of the

  11. Heparinized nanohydroxyapatite/collagen granules for controlled release of vancomycin.

    PubMed

    Coelho, Catarina C; Sousa, Susana R; Monteiro, Fernando J

    2015-10-01

    The purpose of this study was to develop a bone substitute material capable of preventing or treating osteomyelitis through a sustainable release of vancomycin and simultaneously inducing bone regeneration. Porous heparinized nanohydroxyapatite (nanoHA)/collagen granules were characterized using scanning electron microscopy, micro-computed tomography and attenuated total reflectance Fourier transform infrared spectroscopy. After vancomycin adsorption onto the granules, its releasing profile was studied by UV molecular absorption spectroscopy. The heparinized granules presented a more sustainable release over time, in comparison with nonheparinized nanoHA and nanoHA/collagen granules. Vancomycin was released for 360 h and proved to be bioactive until 216 h. Staphylococcus aureus adhesion was higher on granules containing collagen, guiding the bacteria to the material with antibiotic, improving their eradication. Moreover, cytotoxicity of the released vancomycin was assessed using osteoblast cultures, and after 14 days of culture in the presence of vancomycin, cells were able to remain viable, increasing their metabolic activity and colonizing the granules, as observed by scanning electron microscopy and confocal laser scanning microscopy. These findings suggest that heparinized nanoHA/collagen granules are a promising material to improve the treatment of osteomyelitis, as they are capable of releasing vancomycin, eliminating the bacteria, and presented morphological and chemical characteristics to induce bone regeneration. PMID:25778540

  12. Controlled release of sugar and toxicant from a novel device for controlling pest insects.

    PubMed

    Hu, X P; Shasha, B S; McGuire, M R; Prokopy, R J

    1998-01-01

    A novel biodegradable device, designed for long-lasting residual effectiveness of feeding stimulant (sugar) and insecticide (dimethoate) against apple maggot files and other insects, was formulated. The device is an 8-cm diameter fruit-mimicking sphere, consisting of 42-50% sugar entrapped in a mixture of gelatinized corn flour and wheat flour in the presence of glycerin, and coated with a layer of latex paint containing dimethoate and sugar. We found that the outer layer of paint prevents cracking of the sphere upon drying and creates a barrier to control the release of both sugar and dimethoate. Releases of each ingredient were screened first by chemical analysis and then by bioassays in the laboratory and in field cages against apple maggot flies. Chemical analysis demonstrated strong potential for controlled release of water-soluble feeding stimulant and water-insoluble insecticide measured as a function of the amount of rainfall and duration of exposure time. Field results showed greater than 70% insecticidal activity after 11 weeks of sphere exposure in an orchard. This device has the potential to be used for a variety of insect-control applications through manipulating its shape, color and texture into forms known to be attractive to target insects, and by employing various toxicants designed to be effective against such insects. PMID:9685892

  13. Development of a mechanism and an accurate and simple mathematical model for the description of drug release: Application to a relevant example of acetazolamide-controlled release from a bio-inspired elastin-based hydrogel.

    PubMed

    Fernández-Colino, A; Bermudez, J M; Arias, F J; Quinteros, D; Gonzo, E

    2016-04-01

    Transversality between mathematical modeling, pharmacology, and materials science is essential in order to achieve controlled-release systems with advanced properties. In this regard, the area of biomaterials provides a platform for the development of depots that are able to achieve controlled release of a drug, whereas pharmacology strives to find new therapeutic molecules and mathematical models have a connecting function, providing a rational understanding by modeling the parameters that influence the release observed. Herein we present a mechanism which, based on reasonable assumptions, explains the experimental data obtained very well. In addition, we have developed a simple and accurate “lumped” kinetics model to correctly fit the experimentally observed drug-release behavior. This lumped model allows us to have simple analytic solutions for the mass and rate of drug release as a function of time without limitations of time or mass of drug released, which represents an important step-forward in the area of in vitro drug delivery when compared to the current state of the art in mathematical modeling. As an example, we applied the mechanism and model to the release data for acetazolamide from a recombinant polymer. Both materials were selected because of a need to develop a suitable ophthalmic formulation for the treatment of glaucoma. The in vitro release model proposed herein provides a valuable predictive tool for ensuring product performance and batch-to-batch reproducibility, thus paving the way for the development of further pharmaceutical devices. PMID:26838852

  14. Controlled release of sulfasalazine release from "smart" pectin gel microspheres under physiological simulated fluids.

    PubMed

    Costas, Luciana; Pera, Licia M; López, Azucena Gómez; Mechetti, Magdalena; Castro, Guillermo R

    2012-07-01

    Sulfasalazine (SLZ) is a synthetic nonsteroidal anti-inflammatory drug used mainly for the treatment of an inflammatory bowel and other diseases. Two pectins with different methylation degrees were blended to synthesized gel microspheres by ionotropic gelation for SLZ encapsulation. The encapsulation efficiency was found to be around of 99% in all formulations tested. However, different SLZ release profiles related to the methylation degrees of pectin were observed. Mixture of low methylated (LM) and high methylated (HM) pectins in the presence of calcium(II) displayed the best microsphere morphologies among the formulations tested determined by optical and electronic microscopies. The percentage of drug release using a mixture of LM and HM pectins after 255 min in simulated gastric fluid (pH = 1.2), simulated intestinal fluid (pH = 6.8), and phosphate buffer (pH = 7.4) were 15.0%, 47.0%, and 52.2%, respectively. PMID:22371067

  15. Desktop 3D printing of controlled release pharmaceutical bilayer tablets.

    PubMed

    Khaled, Shaban A; Burley, Jonathan C; Alexander, Morgan R; Roberts, Clive J

    2014-01-30

    Three dimensional (3D) printing was used as a novel medicine formulation technique for production of viable tablets capable of satisfying regulatory tests and matching the release of standard commercial tablets. Hydroxypropyl methylcellulose (HPMC 2208) (Methocel™ K100M Premium) and poly(acrylic acid) (PAA) (Carbopol(®) 974P NF) were used as a hydrophilic matrix for a sustained release (SR) layer. Hypromellose(®) (HPMC 2910) was used as a binder while microcrystalline cellulose (MCC) (Pharmacel(®) 102) and sodium starch glycolate (SSG) (Primojel(®)) were used as disintegrants for an immediate release (IR) layer. Commercial guaifenesin bi-layer tablets (GBT) were used as a model drug (Mucinex(®)) for this study. There was a favourable comparison of release of the active guaifenesin from the printed hydrophilic matrix compared with the commercially available GBT. The printed formulations were also evaluated for physical and mechanical properties such as weight variation, friability, hardness and thickness as a comparison to the commercial tablet and were within acceptable range as defined by the international standards stated in the United States Pharmacopoeia (USP). All formulations (standard tablets and 3D printed tablets) showed Korsmeyer-Peppas n values between 0.27 and 0.44 which indicates Fickian diffusion drug release through a hydrated HPMC gel layer. PMID:24280018

  16. Release measurements for materials out of controlled areas

    PubMed

    Auler; Neukater; Franz; Krebs

    2000-07-01

    Large amounts of dismantled materials from nuclear power plants show such a weak level of radioactivity that they could be released after decision measurements. Till some years ago, the decision measurements taken for the release were based only on determining the mass-specific activity of samples by means of gamma spectrometry and/or manual sequential measurements of the surface activity with large area gas flow counters. The choice of an appropriate measuring method, the layout of the release measurement facility (RMF), the way of preparing the material and the development of smart release procedures are very important for a large throughput and an economic performance of the release process. NIS and RADOS have developed RMF based on gross gamma activity. The NIS-RMFs have been applied for the last 10 years for decision measurements in different operated but also in dismantled nuclear power plants. Together with RMFs from RADOS, more than 12,000 Mg of various types of materials have been measured up to now with this method in Germany. PMID:10879881

  17. Controlled release of pentoxifylline from porous chitosan-pectin scaffolds.

    PubMed

    Lin, Hsin-Yi; Yeh, Chih-Tsung

    2010-07-01

    Measures to suppress inflammatory reactions are taken to prevent fibrous encapsulation of implants. It is proposed in this study that tissue engineered scaffolds that can slowly release anti-inflammatory drugs can help reduce inflammatory reactions around implants. Chitosan and chitosan cross-linked with different concentrations of pectin were made into films and porous scaffolds. Results seen from Fourier-transform infrared spectra and thermal gravimetric analysis showed that polyelectrolyte complexation took place between chitosan and pectin units. As the amounts of pectin added to chitosan increased (0%, 0.5%, 1%, and 2%) the scaffolds became more wettable (contact angle decreased from 81 degrees to 76 degrees ), less swellable (swelling ratio decreased from 35% to 30%), and less capable of releasing pentoxifylline (PTX) (release efficacies decreased from 93% to 83%). Higher degrees of pectin cross-linking made the scaffolds more resistant to compression (Young's modulus increased from 2.4 kPa to 3.7 kPa) and more favorable for initial cell attachment (percentage of attached cells increased from 55% to 67%). In vitro tests showed that, with the reduction of PTX release rates, PTX became more effective in inhibiting TNF-alpha and IL-6 production from activated macrophages. This investigation has demonstrated that the changes in the basic drug release properties of chitosan scaffolds were proportional to the amount of pectin added. The changes could help improve the effectiveness of PTX. PMID:20370329

  18. Preparation of hybrid materials for controlled drug release.

    PubMed

    Milczewska, Kasylda; Voelkel, Adam; Zwolińska, Joanna; Jędro, Dorota

    2016-07-01

    Authors obtained hybrid organic-inorganic materials applied in sustained drug delivery. The materials are ibuprofen as a model drug, hydroxyapatite and three different polymers as supports. Influence of the type of employed polymer, an inorganic carrier, on the properties and drug release profiles was estimated. Flory-Huggins interaction parameters, the dispersive component of surface free energy and acid-base characteristic of the surface were used to assess the behavior of the composites in terms of drug release. The experiments were carried out with the use of inverse gas chromatography (IGC), Fourier transform infrared (FTIR) and ultraviolet (UV) techniques. FTIR and ATR-FTIR spectra were collected. The values of [Formula: see text] parameter obtained for all investigated materials (excluding poly(L-lactide) (PLA2)) indicate low or medium activity. The strongest interactions (the lowest values of the Flory-Huggins [Formula: see text] parameter) are observed for PLA2 composition, while the weakest interactions for systems with polyethylene glycol (PEG). Finally, drug release profiles are shown. For materials prepared with Eudragit® (EUD) and PLA, the release of drug was much smaller, which corresponds to lower values of Flory-Huggins parameter. The executed experiments allowed the estimation of the properties of prepared composites. Prepared materials present properties required in sustained drug release and may be successfully applied as drug delivery systems. PMID:26559181

  19. Hyperbranched Polyester Hydrogels with Controlled Drug Release and Cell Adhesion Properties

    PubMed Central

    Zhang, Hongbin; Patel, Alpesh; Gaharwar, Akhilesh K.; Mihaila, Silvia M.; Iviglia, Giorgio; Mukundan, Shilpaa; Bae, Hojae; Yang, Huai; Khademhosseini, Ali

    2013-01-01

    Hyperbranched polyesters (HPE) have a high efficiency to encapsulate bioactive agents, including drugs, genes and proteins, due to their globe-like nanostructure. However, the use of these highly branched polymeric systems for tissue engineering applications has not been broadly investigated. Here, we report synthesis and characterization of photocrosslinkable HPE hydrogels with sustained drug release characteristics for cellular therapies. These HPE can encapsulate hydrophobic drug molecules within the HPE cavities, due to the presence of hydrophobic inner structure that is otherwise difficult to achieve in conventional hydrogels. The functionalization of HPE with photocrosslinkable acrylate moieties renders the formation of hydrogels with highly porous interconnected structure, and mechanically tough network. The compressive modulus of HPE hydrogels was tunable by changing the crosslinking density. The feasibility of using these HPE networks for cellular therapies was investigated by evaluating cell adhesion, spreading and proliferation on hydrogel surface. Highly crosslinked and mechanically stiff HPE hydrogels have higher cell adhesion, spreading, proliferation compared to soft and complaint HPE hydrogels. Overall, we showed that hydrogels made from HPE could be used for biomedical applications that require control cell adhesion and control release of hydrophobic clues. PMID:23394067

  20. [Research advances in the controlled release of growth factor related to blood vessel tissue engineering].

    PubMed

    Wu, Lili; Yuan, Xiaoyan; Yao, Kangde

    2006-08-01

    Growth factors play an important role in cell adhesion and proliferation as well as in tissue regeneration. By incorporating growth factors into polymer scaffolds, controlled release of them can be performed. The release mechanism is varied with the incorporation methods. In this paper, the latest advances in the controlled release of growth factors by blending, hydrogel, microsphere embedding and chemical bonding are reviewed. The potential application of ultrafine fibric embedding in growth factor delivery is described as well. PMID:17002137

  1. Gated silica mesoporous supports for controlled release and signaling applications.

    PubMed

    Coll, Carmen; Bernardos, Andrea; Martínez-Máñez, Ramón; Sancenón, Félix

    2013-02-19

    Blending molecular and supramolecular advances with materials science has resulted in recent years in the development of new organic-inorganic hybrid materials displaying innovative functionalities. One appealing concept in this field is the development of gated nanodevices. These materials are prepared by grafting molecular or supramolecular caps onto the external surface of mesoporous inorganic scaffolds loaded with a particular cargo. The caps or "gates" can then be opened and the cargo delivered at will upon the application of a given stimulus. In this Account, we report some of the recent advances we have made in designing such materials for drug delivery and as new chromo-fluorogenic probes. For controlled release applications, we have prepared capped hybrid mesoporous supports capable of being selectively opened by applying certain physical and chemical stimuli. We report examples of gated materials opened by changes in pH (using polyamines as caps), light (employing spiropyran derivatives or gold nanoparticles), and temperature (using selected paraffins). We also report gated materials opened by enzymes that cleave capping molecules based on lactose, hydrolyzed starch, and peptides. The use of enzymes is especially appealing because molecular caps built of enzyme-specific sequences made of peptides or other cleavable molecules could allow on-command delivery of drugs and biomolecules in specialized contexts. In the second part of the manuscript, we revisit the possibility of using hybrid gated nanomaterials as sensory systems. In such systems, when target analytes interact with the cap, their presence triggers the transport of a dye from pores to the solution, resulting in a chromo-fluorogenic signal that allows their detection. Two approaches are possible. In the first one, pores remain open and the dye can diffuse into the solution, until the presence of a target analyte binds to receptors in the caps and closes the gate. In the second approach, the caps

  2. Mathematical modeling of a flat-membrane-controlled release device

    SciTech Connect

    Ramraj, R.; Farrell, S.; Loney, N.W.

    1999-08-01

    The closed form solution to a mathematical model of a flat membrane device successfully predicts the release profile of benzoic acid. Physically, the device consists of a given concentration of benzoic acid in octanol (reservoir) bounded by a microporous flat film (Cellgard 2400) with water-filled pores. The prediction shows excellent agreement with the experimentally derived release profile (maximum difference < 10%). Predicted results are obtained from the use of the steady state plus the first term of the transient solution (infinite series) and with the use of the first nonzero eigenvalue.

  3. Solid lipid particles in lipid films to control diffusive release of 2-heptanone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlled-release formulations of bioactive agents are gaining increasing interest for effective pest control. Volatile 2-heptanone is a bioactive agent that has shown potential to be used as a pesticide. The aim of this study was to investigate the kinetics of 2-heptanone release, which had been i...

  4. Digital Drug Delivery: On-Off Ultrasound Controlled Antibiotic Release from Coated Matrices with Negligible Background Leaching

    PubMed Central

    Noble, Misty L.

    2014-01-01

    Hydrogels, such as crosslinked poly(2-hydroxyethyl methacrylate) (pHEMA) have been used extensively in controlled release drug delivery systems. Our previous work demonstrated an ultrasound (US)-responsive system based on pHEMA coated with a self-assembled multilayer of C12-C18 methylene chains. The resulting coating was predominantly crystalline and relatively impermeable, forming an US-activated switch that controlled drug release on-demand, and kept the drug within the matrix in the absence of US. The device, as developed did, however, show a low background drug-leaching rate independent of US irradiation. For some applications, it is desirable to have very low or zero background release rates. This was achieved here by a combination of new processing steps, and by copolymerizing HEMA with a relatively hydrophobic monomer, hydroxypropyl methacrylate (HPMA). These advances produced systems with undetectable ciprofloxacin background release rates that are capable of US-facilitated drug release – up to 14-fold increases relative to controls both before and after US exposure. In addition, these observations are consistent with the hypothesis that US-mediated disorganization of the coating allows a transient flux of water into the matrix where its interaction with bound and dissolved drug facilitates its movement both within and out of the matrix. PMID:25045519

  5. Polymer-coated mesoporous silica nanoparticles for the controlled release of macromolecules.

    PubMed

    Bhattacharyya, Sanjib; Wang, Henson; Ducheyne, Paul

    2012-09-01

    With the goal of achieving constant release of large biological molecules over an extended period of time we focused on hybrid inorganic/organic nanoparticles. We synthesized poly(ethylene glycol) (PEG)-coated mesoporous silica nanoparticles (MSNs) with incorporated trypsin inhibitor (TI), a model protein molecule for growth factors. Due to the goal of incorporating large protein molecules the pore size of the as-synthesized MSNs was expanded by a hydrothermal treatment prior to TI incorporation. In vitro release from the MSNs without the thin polymer film shows an initial burst followed by continuous release. In the case of polymer-coated MSNs the initial burst release was completely suppressed and approximate zero order release was achieved for 4 weeks. PMID:22688089

  6. Stimulus responsive drug release from polymer gel.. Controlled release of ionic drug from polyampholyte gel

    NASA Astrophysics Data System (ADS)

    Sutani, Kouichi; Kaetsu, Isao; Uchida, Kumao; Matsubara, Yoshio

    2002-07-01

    2-(Dimethylamino)ethyl methacrylate or Methacryloyloxyethyltrimethylammonium chloride as a cationic monomer was copolymerized by UV with anionic monomer such as acrylic acid (AAc), into a polyampholyte. The pH responsive swelling behaviour and the pH and electro-responsive drug release functions of polyampholyte were investigated. The result showed that a copolymer of cation rich composition swelled at acidic condition, and shrank at alkaline condition. On the other hand, an anion rich copolymer showed a reverse phenomenon. Polyampholyte proved to interact with an ionic drug both by ionic binding and physical adsorption.

  7. PROBABILITY AND CONTROL COST EFFECTIVENESS FOR ACCIDENTAL TOXIC CHEMICAL RELEASES

    EPA Science Inventory

    The paper shows how fault tree analysis (FTA) of a process system can be used to compare the relative effectiveness of various equipment, design, and operating measures for release prevention and protection applied to process streams. It also shows how the costs of various safety...

  8. Designer protein delivery: From natural to engineered affinity-controlled release systems.

    PubMed

    Pakulska, Malgosia M; Miersch, Shane; Shoichet, Molly S

    2016-03-18

    Exploiting binding affinities between molecules is an established practice in many fields, including biochemical separations, diagnostics, and drug development; however, using these affinities to control biomolecule release is a more recent strategy. Affinity-controlled release takes advantage of the reversible nature of noncovalent interactions between a therapeutic protein and a binding partner to slow the diffusive release of the protein from a vehicle. This process, in contrast to degradation-controlled sustained-release formulations such as poly(lactic-co-glycolic acid) microspheres, is controlled through the strength of the binding interaction, the binding kinetics, and the concentration of binding partners. In the context of affinity-controlled release--and specifically the discovery or design of binding partners--we review advances in in vitro selection and directed evolution of proteins, peptides, and oligonucleotides (aptamers), aided by computational design. PMID:26989257

  9. Analysis of achievable disturbance attenuation in a precision magnetically-suspended motion control system

    NASA Technical Reports Server (NTRS)

    Kuzin, Alexander V.; Holmes, Michael L.; Behrouzjou, Roxana; Trumper, David L.

    1994-01-01

    The results of the analysis of the achievable disturbance attenuation to get an Angstrom motion control resolution and macroscopic travel in a precision magnetically-suspended motion control system are presented in this paper. Noise sources in the transducers, electronics, and mechanical vibrations are used to develop the control design.

  10. Enzymatic- and temperature-sensitive controlled release of ultrasmall superparamagnetic iron oxides (USPIOs)

    PubMed Central

    2011-01-01

    Background Drug and contrast agent delivery systems that achieve controlled release in the presence of enzymatic activity are becoming increasingly important, as enzymatic activity is a hallmark of a wide array of diseases, including cancer and atherosclerosis. Here, we have synthesized clusters of ultrasmall superparamagnetic iron oxides (USPIOs) that sense enzymatic activity for applications in magnetic resonance imaging (MRI). To achieve this goal, we utilize amphiphilic poly(propylene sulfide)-bl-poly(ethylene glycol) (PPS-b-PEG) copolymers, which are known to have excellent properties for smart delivery of drug and siRNA. Results Monodisperse PPS polymers were synthesized by anionic ring opening polymerization of propylene sulfide, and were sequentially reacted with commercially available heterobifunctional PEG reagents and then ssDNA sequences to fashion biofunctional PPS-bl-PEG copolymers. They were then combined with hydrophobic 12 nm USPIO cores in the thin-film hydration method to produce ssDNA-displaying USPIO micelles. Micelle populations displaying complementary ssDNA sequences were mixed to induce crosslinking of the USPIO micelles. By design, these crosslinking sequences contained an EcoRV cleavage site. Treatment of the clusters with EcoRV results in a loss of R2 negative contrast in the system. Further, the USPIO clusters demonstrate temperature sensitivity as evidenced by their reversible dispersion at ~75°C and re-clustering following return to room temperature. Conclusions This work demonstrates proof of concept of an enzymatically-actuatable and thermoresponsive system for dynamic biosensing applications. The platform exhibits controlled release of nanoparticles leading to changes in magnetic relaxation, enabling detection of enzymatic activity. Further, the presented functionalization scheme extends the scope of potential applications for PPS-b-PEG. Combined with previous findings using this polymer platform that demonstrate controlled drug

  11. Social Axioms and Achievement across Cultures: The Influence of Reward for Application and Fate Control

    ERIC Educational Resources Information Center

    Zhou, Fan; Leung, Kwok; Bond, Michael Harris

    2009-01-01

    The present research examined the relationships between two social axiom dimensions, reward for application and fate control, with various achievement-related indexes across a wide range of cultures. Results showed that there was no relationship between reward for application and academic achievement or economic competitiveness, but reward for…

  12. A Model of Parental Achievement-Oriented Psychological Control in Academically Gifted Students

    ERIC Educational Resources Information Center

    Garn, Alex C.; Jolly, Jennifer L.

    2015-01-01

    This study investigated achievement-oriented parent socialization as it pertains to school avoidance in a sample of gifted students. A serial mediation model examining relationships among parental achievement-oriented psychological control (APC), fear of academic failure, academic amotivation, and school avoidance was tested. The sample included…

  13. Parental Warmth, Control, and Involvement in Schooling: Predicting Academic Achievement among Korean American Adolescents.

    ERIC Educational Resources Information Center

    Kim, Kyoungho; Rohner, Ronald P.

    2002-01-01

    Explored the relationship between parenting style and academic achievement of Korean American adolescents, investigating the influence of perceived parental warmth and control and improvement in schooling. Survey data indicated that authoritative paternal parenting related to optimal academic achievement. Differences in maternal parenting styles…

  14. Interactions between Student Achievement, Locus of Control, and Two Methods of College Instruction.

    ERIC Educational Resources Information Center

    Root, Jon R.; Gall, Meredith Damien

    1981-01-01

    Fifty-nine undergraduate students, divided into two groups to compare the instructional motivational effects of auto-tutorial and conventional instruction, were tested for achievement via performance (Ac), achievement via independence (Ai), and internal-external locus of control. Significant interaction was found between Ac and the two methods of…

  15. Children's Self-Regulation and School Achievement in Cultural Contexts: The Role of Maternal Restrictive Control.

    PubMed

    Weis, Mirjam; Trommsdorff, Gisela; Muñoz, Lorena

    2016-01-01

    Self-regulation can be developed through parent-child interactions and has been related to developmental outcomes, e.g., such as educational achievement. This study examined cross-cultural differences and similarities in maternal restrictive control, self-regulation (i.e., behavior and emotion regulation) and school achievement and relations among these variables in Germany and Chile. Seventy-six German and 167 Chilean fourth graders, their mothers, and their teachers participated. Mothers and teachers rated children's behavior regulation with a subscale of the Strengths and Difficulties Questionnaire. Children reported their use of emotion regulation strategies on the Questionnaire for the Measurement of Stress and Coping. Mothers rated maternal restrictive control by answering the Parenting Practice Questionnaire. School achievement was assessed by grades for language and mathematics. Results showed higher behavior regulation of German children in comparison to Chilean children and a higher preference of restrictive parental control in Chilean mothers than in German mothers. Regression analyses revealed positive relations between children's behavior regulation and school achievement in Germany and in Chile. Further, in both cultural contexts, maternal restrictive control was related negatively to behavior regulation and positively to anger-oriented emotion regulation. In sum, the study showed the central function of behavior regulation for school achievement underlining negative relations of maternal restrictive control with children's self-regulation and school achievement in diverse cultural contexts. Culturally adapted interventions related to parenting practices to promote children's behavior regulation may assist in also promoting children's school achievement. PMID:27303318

  16. Children's Self-Regulation and School Achievement in Cultural Contexts: The Role of Maternal Restrictive Control

    PubMed Central

    Weis, Mirjam; Trommsdorff, Gisela; Muñoz, Lorena

    2016-01-01

    Self-regulation can be developed through parent-child interactions and has been related to developmental outcomes, e.g., such as educational achievement. This study examined cross-cultural differences and similarities in maternal restrictive control, self-regulation (i.e., behavior and emotion regulation) and school achievement and relations among these variables in Germany and Chile. Seventy-six German and 167 Chilean fourth graders, their mothers, and their teachers participated. Mothers and teachers rated children's behavior regulation with a subscale of the Strengths and Difficulties Questionnaire. Children reported their use of emotion regulation strategies on the Questionnaire for the Measurement of Stress and Coping. Mothers rated maternal restrictive control by answering the Parenting Practice Questionnaire. School achievement was assessed by grades for language and mathematics. Results showed higher behavior regulation of German children in comparison to Chilean children and a higher preference of restrictive parental control in Chilean mothers than in German mothers. Regression analyses revealed positive relations between children's behavior regulation and school achievement in Germany and in Chile. Further, in both cultural contexts, maternal restrictive control was related negatively to behavior regulation and positively to anger-oriented emotion regulation. In sum, the study showed the central function of behavior regulation for school achievement underlining negative relations of maternal restrictive control with children's self-regulation and school achievement in diverse cultural contexts. Culturally adapted interventions related to parenting practices to promote children's behavior regulation may assist in also promoting children's school achievement. PMID:27303318

  17. Photonic hydrogel beads for controlled release of risedronate

    NASA Astrophysics Data System (ADS)

    Khajuria, Deepak K.; Roy Mahapatra, D.

    2014-03-01

    pH-sensitive photonic composite hydrogel beads composed of sodium alginate and risedronate sodium (SA/RIS) was prepared crosslinked by Ca2+ owing to the ionic gelation of SA. The structure and surface morphology of the composite hydrogel beads were characterized by SEM. pH-sensitivity of these composite hydrogels beads and the release behaviors of drug from them were investigated. The results showed that the composite hydrogel beads had good pH-sensitivity. The drug loading and encapsulation efficiency were 27.7% and 92% for RIS, respectively. The cumulative release ratios of RIS from the composite hydrogel beads were 2.47% in pH 2.1 solution and 83 % in pH 6.8 solutions within 24 h, respectively. However, the cumulative release ratio of RIS in pH 7.4 solution reached 91% within 7 h. It is proposed that the novel photonic SA/RIS composite hydrogel bead could possess the potential of an increased intestinal absorption and fewer adverse effects of RIS. The pH and salt response of photonic hydrogel bead, as well as the encapsulation of macromolecules, are promising for applications in biomedicine and biotechnology.

  18. Endogenously triggered electrospun fibres for tailored and controlled antibiotic release.

    PubMed

    Dave, Rachna; Jayaraj, Prithi; Ajikumar, Puthuparampil K; Joshi, Hiren; Mathews, Tom; Venugopalan, Vayalam P

    2013-01-01

    The study was aimed at assessing the potential of enzyme-embedded antibiotic-releasing polycaprolactone (PCL)-based electrospun fibres for tunable drug delivery. This was attempted by incorporation of gentamicin sulphate (GS) in the biocompatible polymer (PCL) matrix, with the degradation of the matrix being ensured by co-impregnating a polymer-degrading enzyme (lipase). Single phase solutions were obtained by hydrophobic ion pairing of GS and surfactant coating of lipase with an anionic surfactant, docusate sodium salt Aerosol OT (AOT). By electrospinning the solution, we could produce PCL fibres containing 11% (w/w) GS-AOT and 28 U (w/w) lipase-AOT. However, sustained release of GS was not obtained. FESEM analysis showed that the fibres did not undergo the expected degradation. Subsequent experiments with unmodified lipase gave satisfactory results; the polymer underwent degradation displaying characteristic perforations in the fibres, suggestive of 'endo-attack'. By modulating the concentrations of lipase (1 to 28 U, w/w), we could obtain GS release rates that varied from 0.53 to 32 mg/ml/d. Accordingly, the lifetime of the fibres could be tuned (10 h to 25 days). The fibres showed excellent antibacterial activity against Staphylococcus aureus throughout their lifetime. PMID:23796032

  19. Long-term Controlled Drug Release from bi-component Electrospun Fibers

    NASA Astrophysics Data System (ADS)

    Xu, Shanshan; Zhang, Zixin; Xia, Qinghua; Han, Charles

    Multi-drug delivery systems with timed programmed release are hard to be produced due to the complex drug release kinetics which mainly refers to the diffusion of drug molecules from the fiber and the degradation of the carrier. This study focused on the whole life-time story of the long-term drug releasing fibrous systems. Electrospun membrane utilizing FDA approved polymers and broad-spectrum antibiotics showed specific drug release profiles which could be divided into three stages based on the profile slope. With throughout morphology observation, cumulative release amount and releasing duration, releasing kinetics and critical factors were fully discussed during three stages. Through changing the second component, approximately linear drug release profile and a drug release duration about 13 days was prepared, which is perfect for preventing post-operative infection. The addition of this semi-crystalline polymer in turn influenced the fiber swelling and created drug diffusion channels. In conclusion, through adjusting and optimization of the blending component, initial burst release, delayed release for certain duration, and especially the sustained release profile could all be controlled, as well as specific anti-bacterial behavior could be obtained.

  20. Investigating the feasibility of temperature-controlled accelerated drug release testing for an intravaginal ring.

    PubMed

    Externbrink, Anna; Clark, Meredith R; Friend, David R; Klein, Sandra

    2013-11-01

    The objective of the present study was to investigate if temperature can be utilized to accelerate drug release from Nuvaring®, a reservoir type intravaginal ring based on polyethylene vinyl acetate copolymer that releases a constant dose of contraceptive steroids over a duration of 3 weeks. The reciprocating holder apparatus (USP 7) was utilized to determine real-time and accelerated etonogestrel release from ring segments. It was demonstrated that drug release increased with increasing temperature which can be attributed to enhanced drug diffusion. An Arrhenius relationship of the zero-order release constants was established, indicating that temperature is a valid parameter to accelerate drug release from this dosage form and that the release mechanism is maintained under these accelerated test conditions. Accelerated release tests are particularly useful for routine quality control to assist during batch release of extended release formulations that typically release the active over several weeks, months or even years, since they can increase the product shelf life. The accelerated method should therefore be able to discriminate between formulations with different release characteristics that can result from normal manufacturing variance. In the case of Nuvaring®, it is well known that the process parameters during the extrusion process strongly influence the polymeric structure. These changes in the polymeric structure can affect the permeability which, in turn, is reflected in the release properties. Results from this study indicate that changes in the polymeric structure can lead to a different temperature dependence of the release rate, and as a consequence, the accelerated method can become less sensitive to detect changes in the release properties. When the accelerated method is utilized during batch release, it is therefore important to take this possible restriction into account and to evaluate the accelerated method with samples from non

  1. Osteogenic effect of controlled released rhBMP-2 in 3D printed porous hydroxyapatite scaffold.

    PubMed

    Wang, Hai; Wu, Gui; Zhang, Jing; Zhou, Kui; Yin, Bo; Su, Xinlin; Qiu, Guixing; Yang, Guang; Zhang, Xianglin; Zhou, Gang; Wu, Zhihong

    2016-05-01

    Recently, 3D printing as effective technology has been highlighted in the biomedical field. Previously, a porous hydroxyapatite (HA) scaffold with the biocompatibility and osteoconductivity has been developed by this method. However, its osteoinductivity is limited. The main purpose of this study was to improve it by the introduction of recombinant human bone morphogenetic protein-2 (rhBMP-2). This scaffold was developed by coating rhBMP-2-delivery microspheres with collagen. These synthesized scaffolds were characterized by Scanning Electron Microscopy (SEM), a delivery test in vitro, cell culture, and the experiments in vivo by a Micro-computed tomography (μCT) scan and histological evaluation of VanGieson staining. SEM results indicated the surface of scaffolds were more fit for the adhesion of hMSCs to coat collagen/rhBMP-2 microspheres. Biphasic release of rhBMP-2 could continue for more than 21 days, and keep its osteoinductivity to induce osteogenic differentiation of hMSCs in vitro. In addition, the experiments in vivo showed that the scaffold had a good bone regeneration capacity. These findings demonstrate that the HA/Collagen/Chitosan Microspheres system can simultaneously achieve localized long-term controlled release of rhBMP-2 and bone regeneration, which provides a promising route for improving the treatment of bone defects. PMID:26896655

  2. Alternating Magnetic Field-Responsive Hybrid Gelatin Microgels for Controlled Drug Release.

    PubMed

    Sung, Baeckkyoung; Shaffer, Steven; Sittek, Michal; Alboslemy, Talib; Kim, Chanjoong; Kim, Min-Ho

    2016-01-01

    Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of smart soft devices for biomedical applications. Although a number of magnetically-responsive drug delivery systems have demonstrated efficacies through either in vitro proof of concept studies or in vivo preclinical applications, their use in clinical settings is still limited by their insufficient biocompatibility or biodegradability. Additionally, many of the existing platforms rely on sophisticated techniques for their fabrications. We recently demonstrated the fabrication of biodegradable, gelatin-based thermo-responsive microgel by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within a three-dimensional gelatin network. In this study, we present a facile method to fabricate a biodegradable drug release platform that enables a magneto-thermally triggered drug release. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and thermo-responsive polymers within gelatin-based colloidal microgels, in conjunction with an alternating magnetic field application system. PMID:26966888

  3. A combined technique based on prilling and microwave assisted treatments for the production of ketoprofen controlled release dosage forms.

    PubMed

    Auriemma, Giulia; Del Gaudio, Pasquale; Barba, Anna Angela; d'Amore, Matteo; Aquino, Rita P

    2011-08-30

    In this study the feasibility of joining prilling and microwave (MW) assisted treatments as combined technique to produce controlled release alginate beads was tested. Beads were produced by prilling (laminar jet break-up) using different polymer concentrations and loaded with ketoprofen, a slightly soluble non-steroidal anti-inflammatory BCS class II drug characterized by low melting point. MW assisted treatments applied using different irradiating conditions were performed as drying/curing step. The effect of formulation conditions and process variables on drying kinetics, particle micromeritics, shape, surface and inner characteristics of the matrix as well as drug loading and drug release behaviour was studied (USP pH change method). The properties of MW dried particles were compared to those dehydrated by convective methods (room conditions and tray oven 105°C). Results showed that MW dried ketoprofen loaded beads were obtained in a very narrow dimensional range retaining shape and size distribution of the hydrates particles. Compared to the traditional drying methods, MW treatments were able to strongly increase drying rate of the hydrated beads achieving faster and controllable dehydration kinetics. Moreover, different regimes of irradiation affected structural properties of the particles such as matrix porosity as well as the solid state of the loaded drug. DSC, X-ray and FTIR analyses indicated complex chemical interactions between the drug and polymer matrix induced by MW, related with the regime of irradiation, that contributes to the differences in release profiles. In fact, MW treatments under different time and irradiating regimes are able to modulate drug release from alginate beads; high levels of irradiation led to beads suitable for immediate release oral dosage forms whereas the lowest regime of irradiation led to beads that achieved a prolonged/sustained release of the drug till 8h in simulated intestinal medium. This study showed that prilling

  4. The effect of polymer properties on direct compression and drug release from water-insoluble controlled release matrix tablets.

    PubMed

    Grund, Julia; Koerber, Martin; Walther, Mathias; Bodmeier, Roland

    2014-07-20

    The objective of this study was to identify and evaluate key polymer properties affecting direct compression and drug release from water-insoluble matrices. Commonly used polymers, such as Kollidon(®) SR, Eudragit(®) RS and ethyl cellulose, were characterized, formulated into tablets and compared with regard to their properties in dry and wet state. A similar site percolation threshold of 65% v/v was found for all polymers in dry state. Key parameters influencing polymer compactibility were the surface properties and the glass transition temperature (T(g)), affecting polymer elasticity and particle size-dependent binding. The important properties observed in dry state also governed matrix characteristics and therefore drug release in wet state. A low T(g) (Kollidon(®) SRrelease retardation was observed in the same order as matrix integrity (Eudragit(®) RScontrolled-release matrix systems. PMID:24746409

  5. The effects of irradiation on controlled drug delivery/controlled drug release systems

    NASA Astrophysics Data System (ADS)

    Ražem, Dušan; Katušin-Ražem, Branka

    2008-03-01

    The research of radiation effects on drugs over the past 60 years has mainly dealt with radiation sterilization of individual active pharmaceutical ingredients (APIs) in the form of pure substances or injectable solutions. However, the emergence of novel systems for drug administration and targeting via controlled drug delivery (CDD) and/or controlled drug release (CDR) has extended the use of irradiation with respect to pharmaceuticals: the capacity of radiation to act as an initiator of crosslinking has been used in the manufacturing and modification of a number of polymeric carriers with an added advantage of reducing the microbial load of products at the same time. The application of irradiation to these novel systems requires the understanding of radiation action not only on APIs alone but also on drug carriers and on the functioning of the integral CDD/CDR systems. In this paper, the significance of CDD/CDR systems is considered with a special emphasis on the role of irradiation for sterilization and crosslinking in the developments over the past 15 years. Radiation sterilization, crosslinking and degradation of the principal forms of drug carrier systems and the effects of irradiation on the release kinetics of APIs are discussed in light of radiation chemical principles. Regulatory aspects pertaining to radiation sterilization of drugs are also considered. Relevant results are summarized in tabular form.

  6. Coordinated coupling control of tethered space robot using releasing characteristics of space tether

    NASA Astrophysics Data System (ADS)

    Huang, Panfeng; Zhang, Fan; Xu, Xiudong; Meng, Zhongjie; Liu, Zhengxiong; Hu, Yongxin

    2016-04-01

    Tethered space robot (TSR) is a new concept of space robot, which is released from the platform satellite, and retrieved via connected tether after space debris capture. In this paper, we propose a new coordinate control scheme for optimal trajectory and attitude tracking, and use releasing motor torque to instead the tension force, since it is difficult to track in practical. Firstly, the 6-DOF dynamics model of TSR is derived, in which the dynamics of tether releasing system is taken into account. Then, we propose and design the coordinated coupled controller, which is composed of a 6-DOF sliding mode controller and a PD controller tether's releasing. Thrust is treated as control input of the 6-DOF sliding mode controller to control the in-plane and out-of-plane angle of the tether and attitude angles of the TSR. The torque of releasing motor is used as input of PD controller, which controls the length rate of space tether. After the verification of the control scheme, finally, the simulation experiment is presented in order to validate the effectiveness of this control method. The results show that TSR can track the optimal approaching trajectory accurately. Simultaneously, the attitude angles can be changed to the desired attitude angles in control period, and the terminal accuracy is ±0.3°.

  7. Core-Shell Composite Hydrogels for Controlled Nanocrystal Formation and Release of Hydrophobic Active Pharmaceutical Ingredients.

    PubMed

    Badruddoza, Abu Zayed Md; Godfrin, P Douglas; Myerson, Allan S; Trout, Bernhardt L; Doyle, Patrick S

    2016-08-01

    Although roughly 40% of pharmaceuticals being developed are poorly water soluble, this class of drugs lacks a formulation strategy capable of producing high loads, fast dissolution kinetics, and low energy input. In this work, a novel bottom-up approach is developed for producing and formulating nanocrystals of poorly water-soluble active pharmaceutical ingredients (APIs) using core-shell composite hydrogel beads. Organic phase nanoemulsion droplets stabilized by polyvinyl alcohol (PVA) and containing a model hydrophobic API (fenofibrate) are embedded in the alginate hydrogel matrix and subsequently act as crystallization reactors. Controlled evaporation of this composite material produces core-shell structured alginate-PVA hydrogels with drug nanocrystals (500-650 nm) embedded within the core. Adjustable loading of API nanocrystals up to 83% by weight is achieved with dissolution (of 80% of the drug) occurring in as little as 30 min. A quantitative model is also developed and experimentally validated that the drug release patterns of the fenofibrate nanocrystals can be modulated by controlling the thickness of the PVA shell and drug loading. Thus, these composite materials offer a "designer" drug delivery system. Overall, our approach enables a novel means of simultaneous controlled crystallization and formulation of hydrophobic drugs that circumvents energy intensive top-down processes in traditional manufacturing. PMID:27249402

  8. Controlled growth factor release from synthetic extracellular matrices

    NASA Astrophysics Data System (ADS)

    Lee, Kuen Yong; Peters, Martin C.; Anderson, Kenneth W.; Mooney, David J.

    2000-12-01

    Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

  9. Goal Orientations, Locus of Control and Academic Achievement in Prospective Teachers: An Individual Differences Perspective

    ERIC Educational Resources Information Center

    Bulus, Mustafa

    2011-01-01

    The aim of this study is to investigate the role of the prospective teachers' locus of control in goal orientations and of both orientations in academic achievement. The participants were 270 undergraduate students studying in different majors at the Faculty of Education in Pamukkale University. Goal Orientations and Locus of Control Scales were…

  10. On the Relation of Locus of Control and L2 Reading and Writing Achievement

    ERIC Educational Resources Information Center

    Ghonsooly, Behzad; Shirvan, Majid Elahi

    2011-01-01

    Locus of control, a psychological construct, has been the focus of attention in recent decades. Psychologists have discussed the effect of locus of control on achieving life goals in social/psychological interactions. While learning a foreign language involves both social interactions and psychological processes, the role and relation of locus of…

  11. Controlling the hydration rate of a hydrophilic matrix in the core of an intravaginal ring determines antiretroviral release.

    PubMed

    Teller, Ryan S; Malaspina, David C; Rastogi, Rachna; Clark, Justin T; Szleifer, Igal; Kiser, Patrick F

    2016-02-28

    Intravaginal ring technology is generally limited to releasing low molecular weight species that can diffuse through the ring elastomer. To increase the diversity of drugs that can be delivered from intravaginal rings, we designed an IVR that contains a drug matrix encapsulated in the core of the IVR whereby the mechanism of drug release is uncoupled from the interaction of the drug with the ring elastomer. We call the device a flux controlled pump, and it is comprised of compressed pellets of a mixture of drug and hydroxypropyl cellulose within the hollow core of the ring. The pump orifice size and chemistry of the polymer pellets control the rate of hydration and diffusion of the drug-containing hydroxypropyl cellulose gel from the device. A mechanistic model describing the hydration and diffusion of the hydroxypropyl cellulose matrix is presented. Good agreement between the quantitative model predictions and the experimental studies of drug release was obtained. We achieved controlled release rates of multiple antiretrovirals ranging from μg/d to mg/d by altering the orifice design, drug loading, and mass of pellets loaded in the device. This device could provide an adaptable platform for the vaginal drug delivery of many molecules. PMID:26723526

  12. PREVENTION REFERENCE MANUAL: CONTROL TECHNOLOGIES. VOLUME 1. PREVENTION AND PROTECTION TECHNOLOGIES FOR CONTROLLING ACCIDENTAL RELEASES OF AIR TOXICS

    EPA Science Inventory

    The volume discusses prevention and protection measures for controlling accidental releases of air toxics. The probability of accidental releases depends on the extent to which deviations (in magnitude and duration) in the process can be tolerated before a loss of chemical contai...

  13. Pulsatile protein release from monodisperse liquid-core microcapsules of controllable shell thickness

    PubMed Central

    Xia, Yujie; Pack, Daniel W.

    2014-01-01

    Purpose Pulsatile delivery of proteins, in which release occurs over a short time after a period of little or no release, is desirable for many applications. This paper investigates the effect of biodegradable polymer shell thickness on pulsatile protein release from biodegradable polymer microcapsules. Methods Using precision particle fabrication (PPF) technology, monodisperse microcapsules were fabricated encapsulating bovine serum albumin (BSA) in a liquid core surrounded by a drug-free poly(lactide-co-glycolide) (PLG) shell of uniform, controlled thickness from 14 to 19 μm. Results When using high molecular weight PLG (Mw 88 kDa), microparticles exhibited the desired core-shell structure with high BSA loading and encapsulation efficiency (55-65%). These particles exhibited very slow release of BSA for several weeks followed by rapid release of 80-90% of the encapsulated BSA within seven days. Importantly, with increasing shell thickness the starting time of the pulsatile release could be controlled from 25 to 35 days. Conclusions Biodegradable polymer microcapsules with precisely controlled shell thickness provide pulsatile release with enhanced control of release profiles. PMID:24831313

  14. An enzyme-responsive controlled release system based on a dual-functional peptide.

    PubMed

    Li, X; Burger, S; O'Connor, A J; Ong, L; Karas, J A; Gras, S L

    2016-04-14

    A new controlled release system was developed by loading a dual-functional peptide (DFP) on a mesoporous silica material. One-pot synthesis produced a DFP that was stimuli responsive, releasing a therapeutic peptide by protease cleavage. The design provides new steps towards smart biomaterials. PMID:26998533

  15. Affinity-mediated capture and release of amphiphilic copolymers for controlling antimicrobial activity.

    PubMed

    Takahashi, Haruko; Akiyoshi, Kazunari; Kuroda, Kenichi

    2015-08-14

    Capture and release of amphiphilic copolymers by a nano-sized polysaccharide gel (nanogel) was controlled by altering the hydrophobic binding affinity between the copolymer chains and nanogel. The antimicrobial activity of captured copolymer chains was suppressed, and regained upon release from the nanogel. PMID:26154063

  16. EXPANDED STARCH AS A FLOATING DOSAGE MATRIX FOR THE CONTROLLED RELEASE OF MODEL DRUG COMPOUNDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch-based materials were tested using model drug compounds to determine the feasibility of using starch as an oral floating dosage matrix. Oral controlled release systems require increased bio-availability, predictable release rates, and site-specific delivery. Starch and model drugs were compo...

  17. A controlled antibiotic release system to prevent orthopedic-implant associated infections: An in vitro study

    PubMed Central

    Gimeno, Marina; Pinczowski, Pedro; Pérez, Marta; Giorello, Antonella; Martínez, Miguel Ángel; Santamaría, Jesús; Arruebo, Manuel; Luján, Lluís

    2015-01-01

    A new device for local delivery of antibiotics is presented, with potential use as a drug-eluting fixation pin for orthopedic applications. The implant consists of a stainless steel hollow tubular reservoir packed with the desired antibiotic. Release takes place through several orifices previously drilled in the reservoir wall, a process that does not compromise the mechanical properties required for the implant. Depending on the antibiotic chosen and the number of orifices, the release profile can be tailored from a rapid release of the load (ca. 20 h) to a combination of rapid initial release and slower, sustained release for a longer period of time (ca. 200 h). An excellent bactericidal action is obtained, with 4-log reductions achieved in as little as 2 h, and total bacterial eradication in 8 h using 6-pinholed implants filled with cefazolin. PMID:26297104

  18. A bench-scale assessment for phosphorus release control of sediment by an oxygen-releasing compound (ORC).

    PubMed

    Yang, Jie; Lin, Feng K; Yang, Lei; Hua, Dan Y

    2015-01-01

    The effects of oxygen-releasing compound (ORC) on the control of phosphorus (P) release as well as the spatial and temporal distribution of P fractions in sediment were studied through a bench-scale test. An ORC with an extended oxygen-releasing capacity was prepared. The results of the oxygen-releasing test showed that the ORC provided a prolonged period of oxygen release with a highly effective oxygen content of 60.6% when compared with powdery CaO2. In the bench-scale test, an ORC dose of 180 g·m(-2) provided a higher inhibition efficiency for P release within 50 days. With the application of the ORC, the dissolved oxygen (DO) concentration and redox potential (ORP) of the overlying water were notably improved, and the dissolved total phosphorus (DTP) was maintained below 0.689 mg·L(-1) compared to 2.906 mg·L(-1) without the ORC treatment. According to the P fractions distribution, the summation of all detectable P fractions in each sediment layer exhibited an enhanced accumulation tendency with the application of ORC. Higher phosphorus retention efficiencies were observed in the second and third layers of sediment from days 10 to 20 with the ORC. Phosphorus was trapped mainly in the form of iron bound P (Fe-P) and organically bound P (O-P) in sediment with the ORC, whereas the effects of the ORC on exchangeable P (EX-P), apatite-associated P (A-P) and detrital P (De-P) in the sediment sample were not significant. The microbial activities of the sediment samples demonstrated that both the dehydrogenase activity (DHA) and alkaline phosphatase activity (APA) in the upper sediment layer increased with the ORC treatment, which indicated that the mineralization of P was accelerated and the microbial biomass was increased. As the accumulation of P suppressed the release of P, the sediment exhibited an increased P retention efficiency with the application of the ORC. PMID:25438131

  19. Controlled release of insect sex pheromones from paraffin wax and emulsions.

    PubMed

    Atterholt, C A; Delwiche, M J; Rice, R E; Krochta, J M

    1999-02-22

    Paraffin wax and aqueous paraffin emulsions can be used as controlled release carriers for insect sex pheromones for mating disruption of orchard pests. Paraffin can be applied at ambient temperature as an aqueous emulsion, adheres to tree bark or foliage, releases pheromone for an extended period of time, and will slowly erode from bark and biodegrade in soil. Pheromone emulsions can be applied with simple spray equipment. Pheromone release-rates from paraffin were measured in laboratory flow-cell experiments. Pheromone was trapped from an air stream with an adsorbent, eluted periodically, and quantified by gas chromatography. Pheromone release from paraffin was partition-controlled, providing a constant (zero-order) release rate. A typical paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E acted as volatility suppressants. A constant release of oriental fruit moth pheromone from paraffin emulsions was observed in the laboratory for more than 100 days at 27 degreesC, with release-rates ranging from 0.4 to 2 mg/day, depending on the concentration and surface area of the dried emulsion. The use of paraffin emulsions is a viable method for direct application of insect pheromones for mating disruption. Sprayable formulations can be designed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degreesC, zero-order release was observed. At 38 degreesC and higher, pheromone oxidation occurred. A partition-controlled release mechanism was supported by a zero-order pheromone release-rate, low air/wax partition coefficients, and pheromone solubility in paraffin. PMID:9895411

  20. Photomanipulation of vasodilation with a blue-light-controllable nitric oxide releaser.

    PubMed

    Ieda, Naoya; Hotta, Yuji; Miyata, Naoki; Kimura, Kazunori; Nakagawa, Hidehiko

    2014-05-14

    Spatiotemporally controllable nitric oxide (NO)-releasers allow us to analyze the physiological effects of NO, a gaseous mediator that modulates many biological signaling networks, and are also candidate chemotherapeutic agents. We designed and synthesized a blue-light-controllable NO releaser, named NOBL-1, which bears an N-nitrosoaminophenol moiety for NO release tethered to a BODIPY dye moiety for harvesting blue light. Photoinduced electron transfer from N-nitrosoaniline to the antenna moiety upon irradiation with relatively noncytotoxic blue light (470-500 nm) should result in NO release with formation of a stable quinone moiety. NO release from NOBL-1 was confirmed by ESR spin trapping and fluorescence detection. Spatially controlled NO release in cells was observed with DAR-4M AM, a fluorogenic NO probe. We also demonstrated temporally controlled vasodilation of rat aorta ex vivo by blue-light-induced NO release from NOBL-1. This compound should be useful for precise examination of the functions of NO with excellent spatiotemporal control. PMID:24731151

  1. Alternate method for achieving temperature control in the -160 to +90 Celcius range

    NASA Technical Reports Server (NTRS)

    Johnson, Kenneth R. (Inventor)

    1995-01-01

    A single-pass method for accurate and precise temperature control in the -160 to +90 C range is discussed. The method exhibited minimal set-point overshoot during temperature transitions. Control to +/-2 C with transitions between set-points of 7 C per minute were achieved. The method uses commercially available temperature controllers and a gaseous nitrogen/liquid nitrogen mixer to dampen the amplitude of cold temperature spikes caused by liquid nitrogen pulsing.

  2. A study comparing biopharmaceutic characteristics of four once daily controlled release diltiazem preparations.

    PubMed

    Hendriks, M G; Dogterom, P; Ebels, J T; Oosterhuis, B; Geertsema, L R; Hulot, T; Bianchetti, G; Jonkman, J H

    1998-01-01

    In the present study we have compared the steady state biopharmaceutic characteristics of four diltiazem once daily controlled release capsules: Mono-Tildiem LP 300 (300 mg), Adizem XL (300 mg), Cardizem (300 mg) and Dilacor (240 mg). Sixteen healthy male volunteers (aged 22.9 +/- 3.3 years, range 19-31 years) completed an open label, multiple oral dose, randomized, four-period crossover study without a washout period in between. The volunteers received each diltiazem formulation once daily for four days. Trough diltiazem and metabolites plasma concentrations were determined on days 3 and 4. The 24-h plasma concentration-time profiles were assessed after the dose on day 4 of each period. The following steady state pharmacokinetic parameters for diltiazem were calculated: the minimum plasma concentration (cmin), the maximum plasma concentration (cmax), the time to reach that concentration (tmax), the time interval during which the plasma concentration exceeds 50% of cmax (t50), the area under the plasma concentration-time curve (AUC72-96) and the peak-to-trough fluctuation (PTF). For the metabolites of diltiazem, N-mono-desmethyl-diltiazem (NDM) and desacetyldiltiazem (DAD), AUC72-96 (AUCNDM and AUCDAD) and the ratio metabolite/parent compound were calculated. Steady state was achieved on day 3. Except one, all controlled release formulations have satisfactory controlled release properties allowing once daily administration. However, significant (P < 0.05) differences were found between the pharmacokinetic characteristics which do not allow exchange of the various formulations. Concentrations well below 50 ng.mL-1 in the morning hours were observed for Dilacor (240 mg) and Adizem XL (300 mg), which could be a disadvantage of these formulations as it is well-known that ischaemic events occur at a higher rate during that part of the day. The plasma concentration profiles NDM and DAD, the major circulating metabolites, parallel the plasma concentration profiles for the

  3. Controlled drug release from Gelucire-based matrix pellets: experiment and theory.

    PubMed

    Siepmann, F; Muschert, S; Flament, M P; Leterme, P; Gayot, A; Siepmann, J

    2006-07-24

    The aim of this work was to elucidate the underlying drug release mechanisms from lipidic matrix pellets, using theophylline and Gelucire 50/02 as model drug and carrier material, respectively. Pellets were prepared by two different techniques: melt-solidification and extrusion-spheronization. The effects of different formulations and processing parameters on the resulting drug release kinetics in 0.1N HCl and phosphate buffer pH 7.4 were studied and the obtained results analyzed using adequate mathematical models in order to get further insight into the underlying mass transport mechanisms. The type of preparation technique was found to strongly affect the underlying drug release mechanisms. Drug release from pellets prepared by the melt-solidification method was primarily controlled by pure diffusion, whereas drug release from pellets prepared by the extrusion-spheronization method was purely diffusion-controlled only at early time points. After approximately 2h, the pellets started to disintegrate, resulting in decreased diffusion pathway lengths and, thus, increased drug release rates. Furthermore, the curing conditions significantly affected the theophylline release kinetics, whereas varying the initial drug loading from 20 to 50% (w/w) resulted only in a slight increase in the relative drug release rate. Interestingly, the effects of the size of pellets prepared by the melt-solidification method on the resulting drug release kinetics could be quantitatively predicted using an analytical solution of Fick's second law of diffusion. These predictions could be verified by independent experiments. PMID:16621362

  4. Controls on Fe(II)-Activated Trace Element Release from Goethite and Hematite

    SciTech Connect

    Frierdich, Andrew J.; Catalano, Jeffrey G.

    2012-03-26

    Electron transfer and atom exchange (ETAE) between aqueous Fe(II) and Fe(III) oxides induces surface growth and dissolution that affects trace element fate and transport. We have recently demonstrated Ni(II) cycling through goethite and hematite (adsorbed Ni incorporates into the mineral structure and preincorporated Ni releases to solution) during Fe(II)-Fe(III) ETAE. However, the chemical parameters affecting net trace element release remain unknown. Here, we examine the chemical controls on Ni(II) and Zn(II) release from Ni- and Zn-substituted goethite and hematite during reaction with Fe(II). Release follows a rate law consistent with surface reaction limited mineral dissolution and suggests that release occurs near sites of Fe(III) reductive dissolution during Fe(II)-Fe(III) ETAE. Metal substituent type affects reactivity; Zn release is more pronounced from hematite than goethite, whereas the opposite trend occurs for Ni. Buildup of Ni or Zn in solution inhibits further release but this resumes upon fluid exchange, suggesting that sustained release is possible under flow conditions. Mineral and aqueous Fe(II) concentrations as well as pH strongly affect sorbed Fe(II) concentrations, which directly control the reaction rates and final metal concentrations. Our results demonstrate that structurally incorporated trace elements are mobilized from iron oxides into fluids without abiotic or microbial net iron reduction. Such release may affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems.

  5. Suitability of Gelucire 50/13 for controlled release formulation of salbutamol sulphate.

    PubMed

    Mohsin, Sabeeh; Rahman, Nisar-Ur; Idrees, Muneeb Ahmad; Sarfraz, Mohammad Khan; Khan, Muhammad Khalid; Mustafa, Ghulam

    2012-01-01

    Gelucire 50/13 (G50/13) was assessed to develop controlled release formulation of salbutamol sulphate (SBL) a highly water soluble drug by semisolid matrix filling capsule technique. Drug release profiles of SBL release by using G50/13 and its blends with other hydrophilic or hydrophobic materials were investigated. Lipid matrix formulations prepared with increasing amount of polymer showed a substantial decrease in release rate of the drug while increasing drug amount in fixed polymer concentration did not significantly affect the release profile. Polyethylene glycol 6000 caused an increased water uptake resulting in fast erosion of the matrix whereas cetostearyl alcohol and stearic acid caused retardation in drug release. These findings confirm that a considerable amount of Gelucire is required alone or in combination with hydrophobic substances in order to sustain the release profiles of water soluble drugs. More linear profile was obtained by using matrix comprising Gelucire/stearic acid blend in more than 85% that was comparable to standard, Ventolin SR tablet. The test formulation showed a significant decrease at pH 1.0 and the drug release rate increased at high stirring speed. Moreover, short term stability of controlled release test formulation indicated slight increase in dissolution rate at high temperature. PMID:22186307

  6. How do different components of Effortful Control contribute to children's mathematics achievement?

    PubMed

    Sánchez-Pérez, Noelia; Fuentes, Luis J; Pina, Violeta; López-López, Jose A; González-Salinas, Carmen

    2015-01-01

    This work sought to investigate the specific contribution of two different components of Effortful Control (EC) -attentional focusing (AF) and inhibitory control- to children's mathematics achievement. The sample was composed of 142 children aged 9-12 year-old. EC components were measured through the Temperament in Middle Childhood Questionnaire (TMCQ; parent's report); math achievement was measured via teacher's report and through the standard Woodcock-Johnson test. Additionally, the contribution of other cognitive and socio-emotional processes was taken into account. Our results showed that only AF significantly contributed to the variance of children's mathematics achievement; interestingly, mediational models showed that the relationship between effortful attentional self-regulation and mathematics achievement was mediated by academic peer popularity, as well as by intelligence and study skills. Results are discussed in the light of the current theories on the role of children's self-regulation abilities in the context of school. PMID:26441758

  7. Biodegradable, multi-layered coatings for controlled release of small molecules†

    PubMed Central

    Amir, Elizabeth; Antoni, Per; Campos, Luis M.; Damiron, Denis; Gupta, Nalini; Amir, Roey J.; Pesika, Noshir; Drockenmuller, Eric

    2014-01-01

    Incorporation of orthogonal functional groups into biodegradable polymers permits the fabrication of multi-layered thin films with improved adhesion and tunable degradation profiles. The bi-layer structure also allows for accurate control over small molecule release. PMID:22499161

  8. Controlled-release fertilizer composition substantially coated with an impermeable layer

    DOEpatents

    Ankeny, Mark

    2016-03-29

    A controlled-release fertilizer composition is provided that is substantially coated with an impermeable layer. The fertilizer composition may further include one or more hollow sections to allow for root penetration and efficient delivery of nutrients.

  9. EMERGENCY RESPONSE PROCEDURES FOR CONTROL OF HAZARDOUS SUBSTANCE RELEASES

    EPA Science Inventory

    Information is provided for selecting the best spill stabilization controls for hazardous substances regulated by the Comprehensive Enviromental Response, Compensation and Liability Act of 1980 (CERCLA). Information is also provided on the onsite assessment of spill severity, app...

  10. The role of metabolic state and obestatin in control of chicken ovarian hormone release.

    PubMed

    Sirotkin, Alexander V; Harrath, Abdel Halim; Grossmann, Roland

    2016-08-01

    The aim of the present study was to examine the role and interrelationships between calorie restriction and obestatin in the control of hormone release by chicken ovarian tissue. For this purpose, we compared the release of progesterone (P), testosteron (T), estradiol (E), and arginine-vasotocin (AVT) by ovarian fragments isolated from chicken subjected and not subjested to food restriction, as well as the response of these ovarian fragments to obestatin additions.It was observed that food restriction promoted release of P, reduced output of T, but did not affect basal E and AVT release. Obestatin addition reduced E, promoted AVT, and did not alter P and T release by ovarian tissue isolated from ad libitum fed chicken. In ovarian fragments of fasted hens it reduced E, promoted T, and did not influence P and AVT release.The present observations demonstrate (1) that obestatin can directly control the release of avian ovarian hormones - regulators of reproduction, (2) that metabolic state can control the release of these hormones, and (3) metabolic state can alter the response of ovarian hormones to obestatin. PMID:27030691

  11. Huperzine A-phospholipid complex-loaded biodegradable thermosensitive polymer gel for controlled drug release.

    PubMed

    Cai, Xiaoqing; Luan, Yuxia; Jiang, Yue; Song, Aixin; Shao, Wei; Li, Zhonghao; Zhao, Zhongxi

    2012-08-20

    The huperzine A-phospholipid complex loaded biodegradable thermosensitive PLGA-PEG-PLGA polymer gel was studied as injectable implant system for controlled release of huperzine-A (HA). First, HA molecules were successfully incorporated into the soybean phosphatidylcholine (SP) molecules to form the huperzine-A-soybean phosphatidylcholine complexes (HA-SPC), which was proved by FT-IR, DSC, XRD, solubility study, TEM, etc. The results indicated that hydrogen bonds and electrostatic interaction between HA and SP molecules play an important role in the formation of HA-SPC. Secondly, the HA-SPC was loaded into biodegradable PLGA-PEG-PLGA thermosensitive gel as injectable implant material to control the release of HA. The in vitro and in vivo drug release behaviors of the prepared products were studied. The in vitro release studies demonstrated that the HA-SPC-loaded gel significantly reduced the initial burst of drug release and extended the release period to about 2 weeks. The in vivo pharmacokinetics study of HA-SPC-loaded gel in rabbits showed that plasma concentration of HA (2.54-0.15ng/mL) was detected for nearly 2 weeks from delivery systems upon single subcutaneous injection. What's more, the in vitro release pattern correlated well with the in vivo pharmacokinetics profile. The present study indicates that HA-SPC loaded PLGA-PEG-PLGA thermal gel may be an attractive candidate vehicle for controlled HA release. PMID:22583846

  12. In Situ Transfection by Controlled Release of Lipoplexes Using Acoustic Droplet Vaporization.

    PubMed

    Juliar, Benjamin A; Bromley, Melissa M; Moncion, Alexander; Jones, Denise C; O'Neill, Eric G; Wilson, Christopher G; Franceschi, Renny T; Fabiilli, Mario L

    2016-07-01

    Localized delivery of nucleic acids to target sites (e.g., diseased tissue) is critical for safe and efficacious gene therapy. An ultrasound-based technique termed acoustic droplet vaporization (ADV) has been used to spatiotemporally control the release of therapeutic small molecules and proteins contained within sonosensitive emulsions. Here, ADV is used to control the release of lipoplex-containing plasmid DNA encoding an enhanced green fluorescent protein reporter-from a sonosensitive emulsion. Focused ultrasound (3.5 MHz, mechanical index (MI) ≥ 1.5) generates robust release of fluorescein (i.e., surrogate payload) and lipoplex from the emulsion. In situ release of the lipoplex from the emulsion using ADV (MI = 1.5, 30 cycles) yields a 55% release efficiency, resulting in 43% transfection efficiency and 95% viability with C3H/10T1/2 cells. Without exposure to ultrasound, the release and transfection efficiencies are 5% and 7%, respectively, with 99% viability. Lipoplex released by ADV retains its bioactivity while the ADV process does not yield any measureable sonoporative enhancement of transfection. Co-encapsulation of Ficoll PM 400 within the lipoplex-loaded emulsion, and its subsequent release using ADV, yield higher transfection efficiency than the lipoplex alone. The results demonstrate that ADV can have utility in the spatiotemporal control of gene delivery. PMID:27191532

  13. Locus of control, test anxiety, academic procrastination, and achievement among college students.

    PubMed

    Carden, Randy; Bryant, Courtney; Moss, Rebekah

    2004-10-01

    114 undergraduates completed the Internal-External Locus of Control scale, the Procrastination Scale, and the Achievement Anxiety Test. They also provided a self-report of their cumulative GPA. Students were divided into two groups by a median-split of 10.5, yielding an internally oriented group of 57 and an externally oriented group of 57. The former students showed significantly lower academic procrastination, debilitating test anxiety, and reported higher academic achievement than the latter. PMID:15587223

  14. Arming embolic beads with anti-VEGF antibodies and controlling their release using LbL technology.

    PubMed

    Sakr, O S; Berndt, S; Carpentier, G; Cuendet, M; Jordan, O; Borchard, G

    2016-02-28

    Transarterial chemoembolization (TACE) is used to treat various types of hypervascular tumors such as hepatocellular carcinoma and renal cancer. However, embolization and blocking of blood vessels nourishing a tumor mass evokes an angiogenic response due to the secretion of vascular endothelial growth factor (VEGF), which results in the formation of new blood vessels and eventually limitation in therapeutic efficacy. The presented work investigates the feasibility of loading the clinically used embolic beads (DC Bead®) with Bevacizumab (BEV), an anti-VEGF antibody, and control its release kinetics via Layer-by-Layer (LbL) coating. This strategy has the aim to achieve high, localized and sustained concentrations of BEV at the tumor site and reduce drug exposure in the systemic circulation. High loading of BEV on lyophilized beads of about 76mg BEV/bead vial was achieved. LbL coating was carried out by depositing alternating layers of the biocompatible polymers alginate and poly-L-lysine. Coating was proven successful by monitoring the reversal of zeta potential after addition of each layer. Morphological changes of the bead surface before and after coating were illustrated using SEM imaging. Moreover, release profiles from different formulations were studied and results showed that optimizing the number of deposited layers effectively slows the release of BEV for three days. Activity of released BEV was studied in different 2D and 3D cell based assays. Released BEV fractions showed comparable activity to fresh BEV solution used as control after 3days. In conclusion, our results suggest the opportunity for loading anti-VEGF antibodies on commercially available embolic beads to increase the efficacy of TACE of hypervascular tumors. PMID:26780173

  15. Metal ion-assisted self-assembly of complexes for controlled and sustained release of minocycline for biomedical applications

    PubMed Central

    Zhang, Zhiling; Wang, Zhicheng; Nong, Jia; Nix, Camilla A.; Ji, Hai-Feng; Zhong, Yinghui

    2015-01-01

    This study reports the development of novel drug delivery complexes self-assembled by divalent metal ion-assisted coacervation for controlled and sustained release of a hydrophilic small drug molecule minocycline (MH). MH is a multifaceted agent that has demonstrated therapeutic effects in infection, inflammation, tumor, as well as cardiovascular, renal, and neurological disorders due to its anti-microbial, anti-inflammatory, and cytoprotective properties. However, the inability to translate the high doses used in experimental animals to tolerable doses in human patients limits its clinical application. Localized delivery can potentially expose the diseased tissue to high concentrations of MH that systemic delivery cannot achieve, while minimizing the side effects from systemic exposure. The strong metal ion binding-assisted interaction enabled high drug entrapment and loading efficiency, and stable long term release for more than 71 days. Released MH demonstrated potent anti-biofilm, anti-inflammatory, and neuroprotective activities. Furthermore, MH release from the complexes is pH-sensitive as the chelation between minocycline and metal ions decreases with pH, allowing ‘smart’ drug release in response to the severity of pathology-induced tissue acidosis. This novel metal ion binding-mediated drug delivery mechanism can potentially be applied to other drugs that have high binding affinity for metal ions and may lead to the development of new delivery systems for a variety of drugs. PMID:25599696

  16. Organosilane functionalization of halloysite nanotubes for enhanced loading and controlled release.

    PubMed

    Yuan, Peng; Southon, Peter D; Liu, Zongwen; Kepert, Cameron J

    2012-09-21

    The surfaces of naturally occurring halloysite nanotubes were functionalized with γ-aminopropyltriethoxysilane (APTES), which was found to have a substantial effect on the loading and subsequent release of a model dye molecule. APTES was mostly anchored at the internal lumen surface of halloysite through covalent grafting, forming a functionalized surface covered by aminopropyl groups. The dye loading of the functionalized halloysite was 32% greater than that of the unmodified sample, and the release from the functionalized halloysite was dramatically prolonged as compared to that from the unmodified one. Dye release was prolonged at low pH and the release at pH 3.5 was approximately three times slower than that at pH 10.0. These results demonstrate that organosilane functionalization makes pH an external trigger for controlling the loading of guest on halloysite and the subsequent controlled release. PMID:22922808

  17. Albizia procera gum as an excipient for oral controlled release matrix tablet.

    PubMed

    Pachuau, Lalduhsanga; Mazumder, Bhaskar

    2012-09-01

    The purpose of this research was to develop and evaluate controlled release matrix tablets of paracetamol based on natural gum exudates of Albizia procera. Procera gum was characterized of its properties like compressibility index, angle of repose, viscosity and moisture content. The interaction between the gum and paracetamol was also studied through differential scanning calorimetry (DSC) and FTIR spectroscopy. Matrix tablets were then prepared by wet granulation method with different concentrations of procera gum and hydroxypropyl methylcellulose (HPMC) and evaluated for their physical properties like weight variation, hardness, friability and content uniformity. Dissolution study was conducted to characterize release mechanism from the matrix system and data were fitted to various kinetic models. The mechanism of drug release from both types of matrix tablets was found to be anomalous type. Results from various evaluations suggested that A. procera gum could be used as drug release retardant in controlled release matrix systems. PMID:24751043

  18. [Research advances on controlled-release mechanisms of nutrients in coated fertilizers].

    PubMed

    Zhang, Haijun; Wu, Zhijie; Liang, Wenju; Xie, Hongtu

    2003-12-01

    Using encapsulation techniques to coat easily soluble fertilizers is an important way to improve fertilizer use efficiency while reduce environmental hazards. Based on a wide range of literature collection on coated fertilizer research, the theories, processes, and characters of nutrient controlled-release from coated fertilizer were discussed, and the factors affecting nutrient controlled-release and the mathematical simulations on it were reviewed. The main tendencies related to this research in China were also put forward. PMID:15031946

  19. Remote-controlled delivery of CO via photoactive CO-releasing materials on a fiber optical device.

    PubMed

    Gläser, Steve; Mede, Ralf; Görls, Helmar; Seupel, Susanne; Bohlender, Carmen; Wyrwa, Ralf; Schirmer, Sina; Dochow, Sebastian; Reddy, Gandra Upendar; Popp, Jürgen; Westerhausen, Matthias; Schiller, Alexander

    2016-08-16

    Although carbon monoxide (CO) delivery materials (CORMAs) have been generated, remote-controlled delivery with light-activated CORMAs at a local site has not been achieved. In this work, a fiber optic-based CO delivery system is described in which the photoactive and water insoluble CO releasing molecule (CORM) manganese(i) tricarbonyl [(OC)3Mn(μ3-SR)]4 (R = nPr, 1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) and poly(methyl methacrylate) non-woven fabrics via the electrospinning technique. SEM images of the hybrid materials show a porous fiber morphology for both polymer supports. The polylactide non-woven fabric was attached to a fiber optical device. In combination with a laser irradiation source, remote-controlled and light-triggered CO release at 405 nm excitation wavelength was achieved. The device enabled a high flexibility of the spatially and timely defined application of CO with the biocompatible hybrid fabric in aqueous media. The rates of liberated CO were adjusted with the light intensity of the laser. CO release was confirmed via ATR-IR spectroscopy, a portable electrochemical CO sensor and a heterogeneous myoglobin assay. PMID:27431097

  20. Controlled-release fertilizer (CRF): a green fertilizer for controlling non-point contamination in agriculture.

    PubMed

    Mao, Xiao-yun; Sun, Ke-jun; Wang, De-han; Liao, Zong-wen

    2005-01-01

    Fertilizers contribute greatly to high yields but also result in environmental non-point contamination, including the emission of greenhouse gas (N2O) and eutrophication of water bodies. How to solve this problem has become a serious challenge, especially for China as its high ecological pressure. Controlled-release fertilizer(CRF) has been developed to minimize the contamination while keeping high yield and has become a green fertilizer for agriculture. Several CRFs made with special coating technology were used for testing the fertilizer effects in yield and environment through pot experiment and field trial. The result indicated that the CRFs had higher N use efficiency, thus reducing N loss through leaching and volatilization while keeping higher yields. Comparing with imported standard CRFs, the test on CRFs showed similar fertilizer effect but with much lower cost. CRFs application is becoming a new approach for minimizing non-point contamination in agriculture. PMID:16295884

  1. Potassium sorbate controlled release from corn starch films.

    PubMed

    López, Olivia V; Giannuzzi, Leda; Zaritzky, Noemí E; García, M Alejandra

    2013-04-01

    Active starch films with glycerol and potassium sorbate were obtained by casting. Native and acetylated corn starches, as well as the mixture of them in equal proportions were used and filmogenic suspensions with pH 4.5 were also prepared. Sorbate concentration decreased during film storage due to its oxidative degradation. Active films resulted more yellow and less transparent than films without sorbate. The minimum inhibitory concentration of sorbate resulted 0.3%, regardless of the starch type and the formulation pH. The use of antimicrobial package was more effective to prevent microbial growth on food surfaces than the use of conventional methods. Additive kinetic release was neither affected by the starch type nor by the formulation pH. Sorbate diffusion process was mathematically modeled satisfactorily. Active films were able to inhibit Candida spp., Penicillium spp., S. aureus and Salmonella spp. growth. Active films extended 21% the shelf life of refrigerated cheese, regardless of the formulation pH. PMID:23827611

  2. Controlled-release approaches towards the chemotherapy of tuberculosis

    PubMed Central

    Saifullah, Bullo; Hussein, Mohd Zobir B; Al Ali, Samer Hasan Hussein

    2012-01-01

    Tuberculosis (TB), caused by the bacteria Mycobacterium tuberculosis, is notorious for its lethality to humans. Despite technological advances, the tubercle bacillus continues to threaten humans. According to the World Health Organization’s 2011 global report on TB, 8.8 million cases of TB were reported in 2010, with a loss of 1.7 million human lives. As drug-susceptible TB requires long-term treatment of between 6 and 9 months, patient noncompliance remains the most important reason for treatment failure. For multidrug-resistant TB, patients must take second-line anti-TB drugs for 18–24 months and many adverse effects are associated with these drugs. Drug-delivery systems (DDSs) seem to be the most promising option for advancement in the treatment of TB. DDSs reduce the adverse effects of drugs and their dosing frequency as well as shorten the treatment period, and hence improve patient compliance. Further advantages of these systems are that they target the disease area, release the drugs in a sustained manner, and are biocompatible. In addition, targeted delivery systems may be useful in dealing with extensively drug-resistant TB because many side effects are associated with the drugs used to cure the disease. In this paper, we discuss the DDSs developed for the targeted and slow delivery of anti-TB drugs and their possible advantages and disadvantages. PMID:23091386

  3. pH-responsive amphiphilic hydrogel networks with IPN structure: a strategy for controlled drug release.

    PubMed

    Liu, Yu-Yang; Fan, Xiao-Dong; Wei, Bo-Rong; Si, Qing-Fa; Chen, Wei-Xing; Sun, Le

    2006-02-01

    A pH-responsive amphiphilic hydrogel with interpenetrating polymer networks (IPN) structure for controlled drug release was proposed. The IPN was constructed with hydrophilic poly(acrylic acid) (PAA) and hydrophobic poly(butyl acrylate) (PBA). Using drug N-acetyl-5-methoxytryptamine (melatonin, MEL) as a model molecule, the controlled drug release behaviors of the IPN were investigated. It is found that not only the release of MEL from the IPN can respond to change in pH, but also the presence of hydrophobic network can overcome disadvantageous burst effect of hydrophilic network. This may be a result of hydrophobic aggregation encapsulating MEL molecules. PMID:16321489

  4. Controlled Autolysis and Enzyme Release in a Recombinant Lactococcal Strain Expressing the Metalloendopeptidase Enterolysin A

    PubMed Central

    Hickey, Rita M.; Ross, R. Paul; Hill, Colin

    2004-01-01

    This study concerns the exploitation of the lytic enzyme enterolysin A (EntL), produced by Enterococcus faecalis strain DPC5280, to elicit the controlled autolysis of starter lactococci. EntL, a cell wall metalloendopeptidase secreted by some E. faecalis strains, can kill a wide range of gram-positive bacteria, including lactococci. The controlled expression of entL, which encodes EntL, was achieved using a nisin-inducible expression system in a lactococcal host. Zymographic analysis of EntL activity demonstrated that active enzyme is produced by the recombinant lactococcal host. Indeed, expression of EntL resulted in almost complete autolysis of the host strain 2 h after induction with nisin. Model cheese experiments using a starter strain in addition to the inducible enterolysin-producing strain showed a 27-fold increase in activity with respect to the release of lactate dehydrogenase in the strain overexpressing EntL, demonstrating the potential of EntL production in large-scale cheese production systems. Indeed, the observation that a wide range of lactic bacteria are sensitive to EntL suggests that EntL-induced autolysis has potential applications with a variety of lactic acid bacteria and could be a basis for probiotic delivery systems. PMID:15006800

  5. Mitofilin regulates cytochrome c release during apoptosis by controlling mitochondrial cristae remodeling

    SciTech Connect

    Yang, Rui-feng; Zhao, Guo-wei; Liang, Shu-ting; Zhang, Yuan; Sun, Li-hong; Chen, Hou-zao; Liu, De-pei

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer Mitofilin deficiency caused disruption of the cristae structures in HeLa cells. Black-Right-Pointing-Pointer Mitofilin deficiency reduced cell proliferation and increased cell sensitivity to apoptotic stimuli. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated the release of cytochrome c from mitochondria. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated STS-induced intrinsic apoptotic pathway without interfering with the activation of Bax. -- Abstract: Mitochondria amplify caspase-dependent apoptosis by releasing proapoptotic proteins, especially cytochrome c. This process is accompanied by mitochondrial cristae remodeling. Our studies demonstrated that mitofilin, a mitochondrial inner membrane protein, acted as a cristae controller to regulate cytochrome c release during apoptosis. Knockdown of mitofilin in HeLa cells with RNAi led to fragmentation of the mitochondrial network and disorganization of the cristae. Mitofilin-deficient cells showed cytochrome c redistribution between mitochondrial cristae and the intermembrane space (IMS) upon intrinsic apoptotic stimuli. In vitro cytochrome c release experiments further confirmed that, compared with the control group, tBid treatment led to an increase in cytochrome c release from mitofilin-deficient mitochondria. Furthermore, the cells with mitofilin knockdown were more prone to apoptosis by accelerating cytochrome c release upon the intrinsic apoptotic stimuli than controls. Moreover, mitofilin deficiency did not interfere with the activation of proapoptotic member Bax upon intrinsic apoptotic stimuli. Thus, mitofilin distinctly functions in cristae remodeling and controls cytochrome c release during apoptosis.

  6. Monensin controlled-release intraruminal capsule for control of bloat in pastured dairy cows.

    PubMed

    Lowe, L B; Ball, G J; Carruthers, V R; Dobos, R C; Lynch, G A; Moate, P J; Poole, P R; Valentine, S C

    1991-01-01

    Monensin, a polyether ionophore antibiotic, is potentially an important agent for bloat relief in dairy cows grazing temperate legume-based pasture. A series of studies was undertaken to determine the effect of monensin, when delivered continuously in the rumen of lactating dairy cows by means of controlled-release capsules (monensin CRC). Such devices release approximately 300 mg/head/day for 100 d. A short-term pilot study made at Ruakura, New Zealand, tested monensin CRC in cows selected for high susceptibility to bloat and grazing lucerne (Medicago sativa) or red clover (Trifolium pratense). Treatment significantly reduced the incidence of bloat, while milk yield and protein yield were increased. There was no effect on fat yield. Following the pilot study, 6 large-scale field experiments involving a total of 368 lactating dairy cows, were made in Australia and New Zealand to confirm the effectiveness of monensin CRC for bloat control and to measure the effect of such treatment on milk production and composition. A severe bloat problem occurred in 2 experiments, mild bloat occurred in 2 others, while no visual signs of bloat were observed in the remaining 2 experiments. Bloat was significantly (P less than 0.05) reduced by monensin CRC treatment when data was pooled over the 4 experiments in which bloat occurred. Daily milk yield was increased in all experiments from a mean of 17.7 in untreated groups to 18.8 kg/head/day (P less than 0.05) in monensin CRC-treated cows. Protein percentage was not affected by treatment, while there was a decrease from 4.29 to 4.10% fat, although total fat yield was not affected.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2018451

  7. Spatially-controlled distribution of HACC in mineralized collagen coatings for improving rhBMP-2 loading and release behavior.

    PubMed

    Chen, Lu; Lin, Jun; Li, Juan; Wang, Xiaozhao; Zhuang, Junjun; Wang, Huiming; Cheng, Kui; Weng, Wenjian

    2016-09-01

    In this study, mineralized collagen (COL) coatings with controlled loading and release of bone morphogenetic protein (rhBMP-2) as well as enhanced osteogenic differentiation were successfully achieved via the spatially-control of hydroxypropyltrimethyl ammonium chloride chitosan (HACC) within the coatings. The distribution of HACC in the inner part (HACC-IN) or the outer part (HACC-OUT) of the coatings were adjusted by different potential values and negative/positive alternations during alternating potentials assisted electrochemical deposition (AP-ECD). It was found that rhBMP-2 loading capacity was remarkably enhanced with the increased incorporation of HACC due to their strong interaction, and the release behavior was also tuned by HACC location. In general, HACC-IN coatings showed a prominent improvement in cytocompatibility and osteogenic differentiation. The main reason is considered that the inner location of HACC can eliminate the negative effect of HACC to initial cellular adhesion and bring to a sustained rhBMP-2 release behavior due to kinetic modification. An optimized coating in this work could load as high as 4644ng/cm(2) rhBMP-2 and release only 25% for 14 days, which consequently leads to a better osteogenic differentiation. This study has thus inspired another promising protocol for designing growth factor incorporated bioactive coatings for bone implants with improved osteointegration. PMID:27151207

  8. Potential application of functional porous TiO2 nanoparticles in light-controlled drug release and targeted drug delivery.

    PubMed

    Wang, Tianyi; Jiang, Haitao; Wan, Long; Zhao, Qinfu; Jiang, Tongying; Wang, Bing; Wang, Siling

    2015-02-01

    Novel multifunctional porous titanium dioxide (TiO2) nanoparticles modified with polyethylenimine (PEI) were developed to explore the feasibility of exploiting the photocatalytic property of titanium dioxide to achieve ultraviolet (UV) light triggered drug release. Additionally, in order to further realize targeting delivery, folic acid, which chemically conjugated to the surface of the functionalized multifunctional porous TiO2 nanoparticles through amide linkage with free amine groups of PEI, was used as a cancer-targeting agent to effectively promote cancer-cell-specific uptake through receptor-mediated endocytosis. And a typical poorly water-soluble anti-cancer drug, paclitaxel, was encapsulated in multifunctional porous TiO2 nanoparticles. The PEI on the surface of multifunctional porous TiO2 nanoparticles could effectively block the channel to prevent premature drug release, thus providing enough circulation time to target cancer cells. Following UV light radiation, PEI molecules on the surface were cut off by the free radicals (OH˙ and O2-) that TiO2 produced, and then the drug loaded in the carrier was released rapidly into the cytoplasm. Importantly, the amount of drug released from multifunctional porous TiO2 nanoparticles can be regulated by the UV-light radiation time to further control the anti-cancer effect. This multifunctional porous TiO2 nanoparticle exhibits a combination of stimuli-triggered drug release and cancer cell targeting. The authors believe that the present study will provide important information for the use of porous TiO2 nanomaterials in light-controlled drug release and targeted therapy. PMID:25462846

  9. Optically controlled release of DNA based on nonradiative relaxation process of quenchers.

    PubMed

    Ogura, Yusuke; Onishi, Atsushi; Nishimura, Takahiro; Tanida, Jun

    2016-06-01

    Optically controlled release of a DNA strand based on a nonradiative relaxation process of black hole quenchers (BHQs), which are a sort of dark quenchers, is presented. BHQs act as efficient energy sources because they relax completely via a nonradiative process, i.e., without fluorescent emission-based energy losses. A DNA strand is modified with BHQs and the release of its complementary strand is controlled by excitation of the BHQs. Experimental results showed that up to 50% of the target strands were released, and these strands were capable of inducing subsequent reactions. The controlled release was localized on a substrate within an area of no more than 5 micrometers in diameter. PMID:27375933

  10. Cross-linked high amylose starch derivatives as matrices for controlled release of high drug loadings.

    PubMed

    Mulhbacher, J; Ispas-Szabo, P; Lenaerts, V; Mateescu, M A

    2001-09-11

    Selection of hydrogels as excipients in controlled drug release systems depends on the characteristics of the gel and of the drug. Three types of derivatives were synthesized from cross-linked high amylose starch (HASCL-6) by substitution of hydroxylic groups with cationic (carboxymethyl: CM), anionic (aminoethyl: AE) and acetate (Ac) groups. These new polymeric excipients are able to control the release over 20 h from monolithic tablets loaded with 20 to 60% drug. Three drugs were used as model tracer: acetaminophen (uncharged), acetylsalicylic acid (having an acidic group) and metformin (having a basic group). It was found that the release of ionic drugs from CM-HASCL-6 and AE-HASCL-6 matrices can be partially controlled by ionic interaction between pendant groups of polymer and drugs. The substitution degree of HASCL-6 derivatives can also be varied to modulate the drug's release time. These derivatives represent a novel generation of pharmaceutical excipients, recommended for high loading dosage formulations. PMID:11532312

  11. Control of accidental releases of hydrogen selenide in vented storage cabinets

    NASA Astrophysics Data System (ADS)

    Fthenakis, V. M.; Moskowitz, P. D.; Sproull, R. D.

    1988-07-01

    Highly toxic hydrogen selenide and hydrogen sulfide gases are used in the production of copper-indium-diselenide photovoltaic cells by reactive sputtering. In the event of an accident, these gases may be released to the atmosphere and pose hazards to public and occupational safety and health. This paper outlines an approach for designing systems for the control of these releases given the uncertainty in release conditions and lack of data on the chemical systems involved. Accidental releases of these gases in storage cabinets can be controlled by either a venturi and packed-bed scrubber and carbon adsorption bed, or containment scrubbing equipment followed by carbon adsorption. These systems can effectively reduce toxic gas emissions to levels needed to protect public health. The costs of these controls (˜0.012/Wp) are samll in comparison with current (˜6/Wp) and projected (˜I/Wp) production costs.

  12. Optically controlled release of DNA based on nonradiative relaxation process of quenchers

    PubMed Central

    Ogura, Yusuke; Onishi, Atsushi; Nishimura, Takahiro; Tanida, Jun

    2016-01-01

    Optically controlled release of a DNA strand based on a nonradiative relaxation process of black hole quenchers (BHQs), which are a sort of dark quenchers, is presented. BHQs act as efficient energy sources because they relax completely via a nonradiative process, i.e., without fluorescent emission-based energy losses. A DNA strand is modified with BHQs and the release of its complementary strand is controlled by excitation of the BHQs. Experimental results showed that up to 50% of the target strands were released, and these strands were capable of inducing subsequent reactions. The controlled release was localized on a substrate within an area of no more than 5 micrometers in diameter. PMID:27375933

  13. Mussel-inspired thermosensitive polydopamine-graft-poly(N-isopropylacrylamide) coating for controlled-release fertilizer.

    PubMed

    Ma, Zhiyuan; Jia, Xin; Hu, Jiamei; Liu, Zhiyong; Wang, Heyun; Zhou, Feng

    2013-12-18

    A thermoresponsive release multi-element compound fertilizer was first reported on the basis of a polydopamine-graft-poly(N-isopropylacrylamide) bilayer coated on a salty core by a combination of dopamine chemistry and surface-initiated atom transfer radical polymerization techniques, and the control of nutrient release in response to the environmental temperature was investigated. The successful synthesized stimuli-responsive fertilizers were confirmed by transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). The release of elements from fertilizer was determined by an inductively coupled plasma (ICP) emission spectrometer. The thermosensitive fertilizers exhibit outstanding stimuli-responsive permeability to encapsulated nutrients, and the release rate of coated elements can be tailored by the ambient temperature. They can release nutrients easily at T < lower critical solution temperature (LCST) but slow at T > LCST. This strategy of grafting thermoresponsive polymer brushes on polydopamine (Pdop)-coated substrates is useful to prepare a stimuli-responsive release system, which can adjust the release rate according to different conditions, and will be effective and promising in the research and development of a stimuli-sensitive controlled-release system. PMID:24308285

  14. Microfluidic Synthesis of Microfibers for Magnetic-Responsive Controlled Drug Release and Cell Culture

    PubMed Central

    Lin, Yung-Sheng; Huang, Keng-Shiang; Yang, Chih-Hui; Wang, Chih-Yu; Yang, Yuh-Shyong; Hsu, Hsiang-Chen; Liao, Yu-Ju; Tsai, Chia-Wen

    2012-01-01

    This study demonstrated the fabrication of alginate microfibers using a modular microfluidic system for magnetic-responsive controlled drug release and cell culture. A novel two-dimensional fluid-focusing technique with multi-inlets and junctions was used to spatiotemporally control the continuous laminar flow of alginate solutions. The diameter of the manufactured microfibers, which ranged from 211 µm to 364 µm, could be well controlled by changing the flow rate of the continuous phase. While the model drug, diclofenac, was encapsulated into microfibers, the drug release profile exhibited the characteristic of a proper and steady release. Furthermore, the diclofenac release kinetics from the magnetic iron oxide-loaded microfibers could be controlled externally, allowing for a rapid drug release by applying a magnetic force. In addition, the successful culture of glioblastoma multiforme cells in the microfibers demonstrated a good structural integrity and environment to grow cells that could be applied in drug screening for targeting cancer cells. The proposed microfluidic system has the advantages of ease of fabrication, simplicity, and a fast and low-cost process that is capable of generating functional microfibers with the potential for biomedical applications, such as drug controlled release and cell culture. PMID:22470443

  15. [Effects of slow/controlled release fertilizers on the growth and nutrient use efficiency of pepper].

    PubMed

    Tang, Shuan-Hu; Zhang, Fa-Bao; Huang, Xu; Chen, Jian-Sheng; Xu, Pei-Zhi

    2008-05-01

    Pot trails were conducted from 2003 to 2005 to study the effects of slow/controlled release fertilizers on the growth and nutrient use efficiency of pepper. The results indicated that in comparison with conventional splitting fertilization (T1), basal application of polymer-coated controlled release fertilizer (T2) enhanced the single fruit mass and vitamin C concentration, improved the root activity, and increased the fruit yield by 8.4%, but no significant effect was observed on the dissoluble sugar concentration in fruit. NH4MgPO4-coated controlled release fertilizer (T3) increased the dissoluble sugar concentration by 5.67%, but had less effect on single fruit mass and vitamin C concentration. Under the application of T3, the root system had a vigorous growth at early stages but became infirm at later stages, resulting in a lower yield. Comparing with T1, the application of 3 slow release fertilizers increased the dissoluble sugar concentration in fruit, enhanced the root activity, but had less effect on the yield. All test slow/controlled release fertilizers increased the use efficiency of N, P, and K significantly, with an exception for T2 which increased the use efficiency of N and K but decreased that of P. It was demonstrated that an appropriate application of slow/controlled release fertilizers could enhance pepper' s root activity and improve nutrient use efficiency. PMID:18655582

  16. Controlled release drug coatings on flexible neural probes.

    PubMed

    Mercanzini, Andre; Reddy, Sai; Velluto, Diana; Colin, Philippe; Maillard, Anne; Bensadoun, Jean-Charles; Bertsch, Arnaud; Hubbell, Jeffrey A; Renaud, Philippe

    2007-01-01

    We present the development, characterization and in vivo validation of a novel drug eluting coating that has been applied to flexible neural probes. The coating consists of drug eluting nanoparticles loaded with an anti-inflammatory drug embedded in a biodegradable polymer. The drug eluting coating is applied to flexible polymer neural probes with platinum electrodes. The drug eluting device is implanted in one hemisphere of a rat, while a control device is implanted in the opposite hemisphere. Impedance measurements are performed to determine the effect of the drug eluting coating on the tissue reaction surrounding the probe and the electrical characteristics of the devices. Probes that are coated with drug eluting coatings show better long term impedance characteristics over control probes. These coatings can be used to increase the reliability and long term success of neural prostheses. PMID:18003541

  17. Control of large space structures: Status report on achievements and current problems

    NASA Technical Reports Server (NTRS)

    Lyons, M. G.; Aubrun, J. N.

    1983-01-01

    The objectives, state-of-the-art, and problems of large space structures control are outlined. The general objectives range from basic deployment and maneuvering, where some vibration modes may be suppressed, to disturbance rejection for very high performance imaging applications. The controls selected generally must produce some combination of eigenvalue/eigenvector and loads modification in order to achieve the mission objectives. An experiment illustrating the dynamic control of a suspended circular plate is described. Analysis methods used in system modelling, signal processing, and process control and monitoring are discussed. Sensor and actuator performance are assessed.

  18. alpha2-Adrenoceptors control the release of noradrenaline but not neuropeptide Y from perivascular nerve terminals.

    PubMed

    Donoso, M Veronica; Carvajal, Andrés; Paredes, Alfonso; Tomic, Alexander; Koenig, Cecilia S; Huidobro-Toro, J Pablo

    2002-09-01

    Neuropeptide Y (NPY) and noradrenaline (NA) are co-transmitters at many sympathetic synapses, but it is not yet clear if their release is independently regulated. To address this question, we quantified the electrically evoked release of these co-transmitters from perivascular nerve terminals to the mesenteric circulation in control and drug-treated rats. 6-Hydroxydopamine reduced the tissue content and the electrically evoked release of ir-NPY and NA as well as the rise in perfusion pressure. A 0.001 mg/kg reserpine reduced the content of ir-NPY and NA, but did not modify their release nor altered the rise in perfusion pressure elicited by the electrical stimuli. However, 0.1mg/kg reserpine reduced both the content and release of NA but decreased only the content but not the release of ir-NPY; the rise in perfusion pressure was halved. Clonidine did not affect the release of ir-NPY while it lowered the outflow of NA, not altering the rise in perfusion pressure elicited by the electrical stimuli. Yohimbine, did not modify the release of ir-NPY but increased the NA outflow, it antagonized the clonidine effect. Therefore, presynaptic alpha2-adrenoceptors modulate the release of NA but not NPY, implying separate regulatory mechanisms. PMID:12217427

  19. The intracellular controlled release from bioresponsive mesoporous silica with folate as both targeting and capping agent

    NASA Astrophysics Data System (ADS)

    Guo, Rui; Li, Le-Le; Zhao, Wen-Hua; Chen, Yu-Xi; Wang, Xiao-Zhu; Fang, Chen-Jie; Feng, Wei; Zhang, Tian-Lan; Ma, Xiang; Lu, Meng; Peng, Shi-Qi; Yan, Chun-Hua

    2012-05-01

    A smart mesoporous silica nanocarrier with intracellular controlled release is fabricated, with folic acid as dual-functional targeting and capping agent. The folate not only improves the efficiency of the nanocarrier internalized by the cancer cells, but also blocks the pores of the mesoporous silica to eliminate premature leakage of the drug. With disulfide bonds as linkers to attach the dual-functional folate within the surface of mesoporous silica, the controlled release can be triggered in the presence of reductant dithiothreitol (DTT) or glutathione (GSH). The cellular internalization via folate-receptor-mediated endocytosis and the intracellular controlled release of highly toxic anticancer drug DOX were demonstrated with an in vitro HeLa cell culture, indicating an efficient cancer-targeted drug delivery.A smart mesoporous silica nanocarrier with intracellular controlled release is fabricated, with folic acid as dual-functional targeting and capping agent. The folate not only improves the efficiency of the nanocarrier internalized by the cancer cells, but also blocks the pores of the mesoporous silica to eliminate premature leakage of the drug. With disulfide bonds as linkers to attach the dual-functional folate within the surface of mesoporous silica, the controlled release can be triggered in the presence of reductant dithiothreitol (DTT) or glutathione (GSH). The cellular internalization via folate-receptor-mediated endocytosis and the intracellular controlled release of highly toxic anticancer drug DOX were demonstrated with an in vitro HeLa cell culture, indicating an efficient cancer-targeted drug delivery. Electronic supplementary information (ESI) available: the details of XRD patterns and HRTEM images of the materials, release profile of F⊂M-F in an acidic solution, intracellular uptake measurement with flow cytometry, intracellular release measurement with confocal fluorescence microscopy, selected distance of folate derivatives. See DOI: 10

  20. Use of controlled internal drug releasing (CIDR) devices to control reproduction in goats: A review.

    PubMed

    Knights, Marlon; Singh-Knights, Doolarie

    2016-09-01

    High reproductive rates are necessary in order to increase the productivity of goat operations. Progesterone and its analogues are widely used in other species to control the reproductive system to facilitate synchronized births, induce fertile estrus or to facilitate the use of assisted reproductive techniques with the goal of increasing productivity of livestock. Progesterone impregnated controlled internal drug releasing (CIDR) devices are approved for delivery of the natural hormone progesterone to synchronize and induce fertile estrus in sheep. A few studies have reported a high estrous response and pregnancy rates when CIDRs are used to induce estrus in goats. However, significant variation exists in the duration of treatment (5-16 days) and in the use of exogenous gonadotropins as part of the treatment protocol. As gonadotropins are not currently approved for commercial use in small ruminants in the USA, studies are needed to determine the necessity for exogenous gonadotropins and whether they can be replaced by enhancing endogenous secretion through photoperiodic manipulation of the doe and \\ or increase stimulation through the 'buck-effect'. Future studies must not only evaluate efficacy, but should consider the economic feasibility of using CIDRs in commercial production systems. PMID:27192693

  1. E-Control: First Public Release of Remote Control Software for VLBI Telescopes

    NASA Technical Reports Server (NTRS)

    Neidhardt, Alexander; Ettl, Martin; Rottmann, Helge; Ploetz, Christian; Muehlbauer, Matthias; Hase, Hayo; Alef, Walter; Sobarzo, Sergio; Herrera, Cristian; Himwich, Ed

    2010-01-01

    Automating and remotely controlling observations are important for future operations in a Global Geodetic Observing System (GGOS). At the Geodetic Observatory Wettzell, in cooperation with the Max-Planck-Institute for Radio Astronomy in Bonn, a software extension to the existing NASA Field System has been developed for remote control. It uses the principle of a remotely accessible, autonomous process cell as a server extension for the Field System. The communication is realized for low transfer rates using Remote Procedure Calls (RPC). It uses generative programming with the interface software generator idl2rpc.pl developed at Wettzell. The user interacts with this system over a modern graphical user interface created with wxWidgets. For security reasons the communication is automatically tunneled through a Secure Shell (SSH) session to the telescope. There are already successful test observations with the telescopes at O Higgins, Concepcion, and Wettzell. At Wettzell the software is already used routinely for weekend observations. Therefore the first public release of the software is now available, which will also be useful for other telescopes.

  2. Grade 10 English Language Arts Released Test Items: Sample Student Work Illustrating GEE 21's Achievement Levels.

    ERIC Educational Resources Information Center

    Louisiana State Dept. of Education, Baton Rouge.

    In the school year 2000-2001 students in Grade 10 took the Graduation Exit Examination for the 21st Century (GEE 21) Language Arts and Mathematics tests for the first time. For GEE 21, student scores are reported in terms of five achievement levels: Advanced, Proficient, Basic, Approaching Basic, and Unsatisfactory. This booklet is part of a…

  3. Multi-unit dosage formulations of theophylline for controlled release applications.

    PubMed

    Uhumwangho, Michael U; Okor, Roland S

    2007-01-01

    The study was carried out to investigate the drug release profiles of multi-unit dosage formulations of theophylline consisting of both the fast and slow release components in a unit dose. The fast release component consisted of conventional granules of theophylline formed by mixing the drug powder with starch mucilage (20% w/v) while the slow release component consisted of wax granulations of theophylline formed by triturating the drug powder with a melted Carnauba wax (drug:wax ratio, 4:1). The granules were either filled into capsules or tabletted. In the study design, the drug release characteristics of the individual fast or slow release particles were first determined separately and then mixed in various proportions for the purpose of optimizing the drug release profiles. The evaluating parameters were the prompt release in the first 1 h (mp), the maximum release (m infinity) and the time to attain it (t infinity). Total drug content in each capsule or tablet was 300 mg and two of such were used in dissolution studies. The release kinetics and hence the release mechanism was confirmed by measuring the linear regression coefficient (R2 values) of the release data. The release kinetics was generally most consistent with the Higuchi square root of time relationship (R2 = 0.95). indicating a diffusion-controlled mechanism. The mp (mg) and t infinity (h) values for capsules and tablets of the conventional granules were (420 mg, 3 h) and (348 mg, 5 h), respectively, while for the capsules and tablets of the wax granulations mp and t infinity values were (228 mg, 9 h) and (156 mg, 12 h), respectively, indicating that a combination of wax granulation and tableting markedly retarded drug release. In the multi-unit dose formulations where the conventional and wax granulations were mixed in the ratios 2:1, 1:1 and 1:2 (conventional: matrix), the m infinity and t infinity values for the capsules were (378 mg, 6 h), (326 mg, 6 h) and (272 mg, 7 h), reSpectively. The

  4. Controlling pH in shake flasks using polymer-based controlled-release discs with pre-determined release kinetics

    PubMed Central

    2011-01-01

    Background There are significant differences in the culture conditions between small-scale screenings and large-scale fermentation processes. Production processes are usually conducted in fed-batch cultivation mode with active pH-monitoring and control. In contrast, screening experiments in shake flasks are usually conducted in batch mode without active pH-control, but with high buffer concentrations to prevent excessive pH-drifts. These differences make it difficult to compare results from screening experiments and laboratory and technical scale cultivations and, thus, complicate rational process development. In particular, the pH-value plays an important role in fermentation processes due to the narrow physiological or optimal pH-range of microorganisms. To reduce the differences between the scales and to establish a pH-control in shake flasks, a newly developed easy to use polymer-based controlled-release system is presented in this paper. This system consists of bio-compatible silicone discs embedding the alkaline reagent Na2CO3. Since the sodium carbonate is gradually released from the discs in pre-determined kinetics, it will ultimately compensate the decrease in pH caused by the biological activity of microorganisms. Results The controlled-release discs presented here were successfully used to cultivate E. coli K12 and E. coli BL21 pRSET eYFP-IL6 in mineral media with glucose and glycerol as carbon (C) sources, respectively. With glucose as the C-source it was possible to reduce the required buffer concentration in shake flask cultures by 50%. Moreover, with glycerol as the C-source, no buffer was needed at all. Conclusions These novel polymer-based controlled-release discs allowed buffer concentrations in shake flask media to be substantially reduced or omitted, while the pH remains in the physiological range of the microorganisms during the whole cultivation time. Therefore, the controlled-release discs allow a better control of the pH, than merely using

  5. Effortful Control and Impulsivity as Concurrent and Longitudinal Predictors of Academic Achievement

    ERIC Educational Resources Information Center

    Valiente, Carlos; Eisenberg, Nancy; Spinrad, Tracy L.; Haugen, Rg; Thompson, Marilyn S.; Kupfer, Anne

    2013-01-01

    The goal of this study was to test if both effortful control (EC) and impulsivity, a reactive index of temperament, uniquely predict adolescents' academic achievement, concurrently and longitudinally (Time 1: "N" = 168, X-bar[subscript age] = 12 years). At Time 1, parents and teachers reported on students' EC and impulsivity.…

  6. Examining Perceived Control Level and Instability as Predictors of First-Year College Students' Academic Achievement

    ERIC Educational Resources Information Center

    Stupnisky, Robert H.; Perry, Raymond P.; Hall, Nathan C.; Guay, Frederic

    2012-01-01

    The aim of the present study was to examine the intraindividual level and instability of perceived academic control (PC) among first-year college students, and their predictive effects on academic achievement. Two studies were conducted measuring situational (state) PC on different schedules: Study 1 (N = 242) five times over a 6-month period and…

  7. Locus of Control in Achievement and Affiliation (MMCS) as Related to Pathologies.

    ERIC Educational Resources Information Center

    Childers, John; Lao, Rosina C.

    The Multidimensional-Multiattributional Causality Scale (MMCS) is a goal-specific scale developed to assess locus of control in the areas of achievement and affiliation. The relationship between the MMCS and feelings of depression, hopelessness, and perceived stress was examined to validate the MMCS and determine if specific expectancies take…

  8. On-Line Tutoring for Math Achievement Testing: A Controlled Evaluation

    ERIC Educational Resources Information Center

    Beal, Carole R.; Walles, Rena; Arroyo, Ivon; Woolf, Beverly P.

    2007-01-01

    We report the results of a controlled evaluation of an interactive on-line tutoring system for high school math achievement test problem solving. High school students (N = 202) completed a math pre-test and were then assigned by teachers to receive interactive on-line multimedia tutoring or their regular classroom instruction. The on-line tutored…

  9. Autonomy Support versus Psychological Control, Perfectionism, and Taiwanese Adolescents' Achievement Goals

    ERIC Educational Resources Information Center

    Shih, Shu-Shen

    2013-01-01

    The author attempted to explore potential antecedents of achievement goals and relations of teacher and parental autonomy support versus psychological control to Taiwanese adolescents' perfectionistic tendencies. A total of 512 eighth-grade students completed self-reported questionnaires assessing variables of interest. Results indicated that…

  10. Training Theory of Mind and Executive Control: A Tool for Improving School Achievement?

    ERIC Educational Resources Information Center

    Kloo, Daniela; Perner, Josef

    2008-01-01

    In the preschool years, there are marked improvements in theory of mind (ToM) and executive functions. And, children's competence in these two core cognitive domains is associated with their academic achievement. Therefore, training ToM and executive control could be a valuable tool for improving children's success in school. This article reviews…

  11. The Effect of Inhibitory Control on General Mathematics Achievement and Fraction Comparison in Middle School Children

    ERIC Educational Resources Information Center

    Gómez, David Maximiliano; Jiménez, Abelino; Bobadilla, Roberto; Reyes, Cristián; Dartnell, Pablo

    2015-01-01

    Individual differences in inhibitory control have been shown to relate to general mathematics achievement, but whether this relation varies for specific areas within mathematics is a question that remains open. Here, we evaluate if inhibitory processes play a specific role in the particular case of fraction comparison, where learners must ignore…

  12. Diagnosis, Remediation, and Locus of Control: Effects on Immediate and Retained Achievement and Attitudes.

    ERIC Educational Resources Information Center

    Saunders-Harris, Ramona; Yeany, Russell H.

    1981-01-01

    Subjects were assessed for locus of control and experienced either: no diagnosis; diagnosis; or, diagnosis and remediation. Immediate achievement was measured twice during the experiment; retention was measured 30 days later. Findings suggest that diagnostic or diagnostic/remedial instruction is effective in increasing middle school science…

  13. Self-assembled liquid-crystalline folate nanoparticles for in vitro controlled release of doxorubicin.

    PubMed

    Misra, Rahul; Mohanty, Sanat

    2015-02-01

    Liquid-crystalline folate nanoparticles are ordered in structure which offers several advantages like high encapsulation of drugs, controlled release rates, biocompatible in nature. Moreover, it facilitates the cellular uptake of nanodrugs without any extra step of folate ligand based targeting. The size of these nanocarriers as well as the release profiles of drugs from these nano-carriers can be controlled precisely. Folate molecules self-assemble in ordered stacks and columns even at low concentration of 0.1wt%. Doxorubicin molecules get intercalated within the folate stacks and are developed into nanoparticles. These nanoparticles are composed of highly ordered folate self-assembly which encapsulate doxorubicin molecules. These drug molecules can be released in a controlled manner by disrupting this assembly in the environment of monovalent cations. The ordered structure of folate nanoparticles offers low drug losses of about 4-5%, which is significant in itself. This study reports the size-control method of forming doxorubicin encapsulated folate nanoparticles as well as the parameters to control the release rates of doxorubicin through liquid-crystalline folate nanoparticles. It has been demonstrated that doxorubicin release rates can be controlled by controlling the size of the nanoparticles, cross-linking cation and cross-linking concentration. The effect of different factors like drug loading, release medium, and pH of the medium on doxorubicin release rates was also studied. Moreover, this study also addresses the comparative in vitro cytotoxic performance of Doxorubicin loaded folate nanoparticles and cellular uptake of nano-carriers on cancer and normal cell line. PMID:25661378

  14. Controlled release of an anti-cancer drug from DNA structured nano-films

    NASA Astrophysics Data System (ADS)

    Cho, Younghyun; Lee, Jong Bum; Hong, Jinkee

    2014-02-01

    We demonstrate the generation of systemically releasable anti-cancer drugs from multilayer nanofilms. Nanofilms designed to drug release profiles in programmable fashion are promising new and alternative way for drug delivery. For the nanofilm structure, we synthesized various unique 3-dimensional anti cancer drug incorporated DNA origami structures (hairpin, Y, and X shaped) and assembled with peptide via layer-by-layer (LbL) deposition method. The key to the successful application of these nanofilms requires a novel approach of the influence of DNA architecture for the drug release from functional nano-sized surface. Herein, we have taken first steps in building and controlling the drug incorporated DNA origami based multilayered nanostructure. Our finding highlights the novel and unique drug release character of LbL systems in serum condition taken full advantages of DNA origami structure. This multilayer thin film dramatically affects not only the release profiles but also the structure stability in protein rich serum condition.

  15. Controlled release of an anti-cancer drug from DNA structured nano-films

    PubMed Central

    Cho, Younghyun; Lee, Jong Bum; Hong, Jinkee

    2014-01-01

    We demonstrate the generation of systemically releasable anti-cancer drugs from multilayer nanofilms. Nanofilms designed to drug release profiles in programmable fashion are promising new and alternative way for drug delivery. For the nanofilm structure, we synthesized various unique 3-dimensional anti cancer drug incorporated DNA origami structures (hairpin, Y, and X shaped) and assembled with peptide via layer-by-layer (LbL) deposition method. The key to the successful application of these nanofilms requires a novel approach of the influence of DNA architecture for the drug release from functional nano-sized surface. Herein, we have taken first steps in building and controlling the drug incorporated DNA origami based multilayered nanostructure. Our finding highlights the novel and unique drug release character of LbL systems in serum condition taken full advantages of DNA origami structure. This multilayer thin film dramatically affects not only the release profiles but also the structure stability in protein rich serum condition. PMID:24518218

  16. Controlled release of an anthrax toxin-neutralizing antibody from hydrolytically degradable polyethylene glycol hydrogels.

    PubMed

    Liang, Yingkai; Coffin, Megan V; Manceva, Slobodanka D; Chichester, Jessica A; Jones, R Mark; Kiick, Kristi L

    2016-01-01

    In this study, hydrophilic and hydrolytically degradable poly (ethylene glycol) (PEG) hydrogels were formed via Michael-type addition and employed for sustained delivery of a monoclonal antibody against the protective antigen of anthrax. Taking advantage of the PEG-induced precipitation of the antibody, burst release from the matrix was avoided. These hydrogels were able to release active antibodies in a controlled manner from 14 days to as long as 56 days in vitro by varying the polymer architectures and molecular weights of the precursors. Analysis of the secondary and tertiary structure and the in vitro activity of the released antibody showed that the encapsulation and release did not affect the protein conformation or functionality. The results suggest the promise for developing PEG-based carriers for sustained release of therapeutic antibodies against toxins in various applications. PMID:26223817

  17. Controlled protein release from polyethyleneimine-coated poly(L-lactic acid)/pluronic blend matrices.

    PubMed

    Park, T G; Cohen, S; Langer, R

    1992-01-01

    Protein release from degradable polymer matrices, composed of poly(L-lactic acid) and its blends with Pluronic surfactant, was investigated with and without the aqueous coating of an adsorptive water-soluble polymer, polyethyleneimine (PEI). PEI is a highly branched cationic polymer containing primary, secondary, and tertiary amino groups in its backbone. The treatment of PEI for PLA/Pluronic blend films exhibited a remarkable decrease in the "burst" release of protein at an initial stage and a significant extension in the protein release period. Protein release profiles could be controlled by varying PEI treatment time and its concentration. Our results suggest that PEI diffuses into the polymer matrices and crosslinks protein molecules by ionic interactions. Such a PEI-protein network near the surface region of matrix may act as a diffusional barrier for further release of protein molecules. PMID:1589407

  18. Development and evaluation of alginate-chitosan nanocapsules for controlled release of acetamiprid.

    PubMed

    Kumar, Sandeep; Chauhan, Neetu; Gopal, Madhuban; Kumar, Rajesh; Dilbaghi, Neeraj

    2015-11-01

    Smart formulations based on nanomaterials have the capability to reduce the consumption of hazardous pesticides and their impact on human health and environment. Nanoformulations of agrochemicals have the potential to improve food productivity without compromising with the ecosystem. In the present work, controlled release nanocapsules containing acetamiprid were prepared by polyelectrolyte complexation of two natural macromolecules, i.e. alginate and chitosan. The size, morphology and chemical interaction studies of the prepared nanocapsules were investigated by Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). The zetapotential studies revealed stability of the nanocapsules. TEM results show spherical morphology of the nanocapsules. The encapsulation efficiency was found to be 62% as quantified by Ultra High Pressure Liquid Chromatography (UHPLC). Nanocapsules were analysed for controlled release in vitro at three different pH. Maximum release was observed at pH 10 followed by pH 7 and 4, respectively. A non-Fickian release mechanism was found to be followed by the nanoformulation. A controlled release pattern was also found from nanoformulation as compared to commercial formulation in soil. Thus this formulation can reduce the frequency of application of pesticides by controlling the release and will subsequently reduce their side effects. PMID:26321424

  19. Controlled release properties of zein-fatty acid blend films for multiple bioactive compounds.

    PubMed

    Arcan, Iskender; Yemenicioğlu, Ahmet

    2014-08-13

    To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ⁹, linoleic (C18:2)Δ(9,12), or lauric (C₁₂) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm². The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food. PMID:25025594

  20. [Effects of mechanical transplanting of rice with controlled release bulk blending fertilizer on rice yield and soil fertility].

    PubMed

    Zhang, Xuan; Ding, Jun-Shan; Liu, Yan-Ling; Gu, Yan; Han, Ke-Feng; Wu, Liang-Huan

    2014-03-01

    Abstract: A 2-year field experiment with a yellow-clay paddy soil in Zhejiang Province was conducted to study the effects of different planting measures combined with different fertilization practices on rice yield, soil nutrients, microbial biomass C and N and activities of urease, phosphatase, sucrase and hydrogen peroxidase at the maturity stage. Results showed that mechanical transplanting of rice with controlled release bulk blending (BB) fertilizer (BBMT) could achieve a significantly higher mean yield than traditional manual transplanting with traditional fertilizer (TFTM) and direct seeding with controlled release BB fertilizer (BBDS) by 16.3% and 27.0%, respectively. The yield by BBMT was similar to that by traditional manual transplanting with controlled release BB fertilizer (BBTM). Compared with TFTM, BBMT increased the contents of soil total-N, available N, available P and microbial biomass C, and the activities of urease, sucrase and hydrogen peroxidase by 21.5%, 13.6%, 41.2%, 27.1%, 50.0%, 22.5% and 46.2%, respectively. Therefore, BBMT, a simple high-efficiency rice cultivation method with use of a light-weighted mechanical transplanter, should be widely promoted and adopted. PMID:24984497

  1. Reversible Local and Global Switching in Multicomponent Supramolecular Networks: Controlled Guest Release and Capture at the Solution/Solid Interface.

    PubMed

    Lee, Shern-Long; Fang, Yuan; Velpula, Gangamallaiah; Cometto, Fernando P; Lingenfelder, Magalí; Müllen, Klaus; Mali, Kunal S; De Feyter, Steven

    2015-12-22

    Dynamically switchable supramolecular systems offer exciting possibilities in building smart surfaces, the structure and thus the function of which can be controlled by using external stimuli. Here we demonstrate an elegant approach where the guest binding ability of a supramolecular surface can be controlled by inducing structural transitions in it. A physisorbed self-assembled network of a simple hydrogen bonding building block is used as a switching platform. We illustrate that the reversible transition between porous and nonporous networks can be accomplished using an electric field or applying a thermal stimulus. These transitions are used to achieve controlled guest release or capture at the solution-solid interface. The electric field and the temperature-mediated methods of guest release are operative at different length scales. While the former triggers the transition and thus guest release at the nanometer scale, the latter is effective over a much larger scale. The flexibility associated with physisorbed self-assembled networks renders this approach an attractive alternative to conventional switchable systems. PMID:26550765

  2. Role of Parenting Style in Achieving Metabolic Control in Adolescents With Type 1 Diabetes

    PubMed Central

    Shorer, Maayan; David, Ravit; Schoenberg-Taz, Michal; Levavi-Lavi, Ifat; Phillip, Moshe; Meyerovitch, Joseph

    2011-01-01

    OBJECTIVE To examine the role of parenting style in achieving metabolic control and treatment adherence in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS Parents of 100 adolescents with type 1 diabetes completed assessments of their parenting style and sense of helplessness. Parents and patients rated patient adherence to the treatment regimen. Glycemic control was evaluated by HbA1c values. RESULTS An authoritative paternal parenting style predicted better glycemic control and adherence in the child; a permissive maternal parenting style predicted poor adherence. A higher sense of helplessness in both parents predicted worse glycemic control and lesser adherence to treatment. Parental sense of helplessness was a significant predictor of diabetes control after correcting for other confounders (patient age, sex, and treatment method). CONCLUSIONS An authoritative nonhelpless parenting style is associated with better diabetes control in adolescents. Paternal involvement is important in adolescent diabetes management. These results have implications for psychological interventions. PMID:21788643

  3. Synthesis and characterization of a HAp-based biomarker with controlled drug release for breast cancer.

    PubMed

    González, Maykel; Merino, Ulises; Vargas, Susana; Quintanilla, Francisco; Rodríguez, Rogelio

    2016-04-01

    A biocompatible hybrid porous polymer-ceramic material was synthesized to be used as a biomarker in the treatment of breast cancer. This device was equipped with the capacity to release medicaments locally in a controlled manner. The biomaterial was Hydroxyapatite(HAp)-based and had a controlled pore size and pore volume fraction. It was implemented externally using a sharp end and a pair of barbed rings placed opposite each other to prevent relative movement once implanted. The biomarker was impregnated with cis-diamine dichloride platinum (II) [Cl2-Pt-(NH3)2]; the rate of release was obtained using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and release occurred over the course of three months. Different release profiles were obtained as a function of the pore volume fraction. The biomaterial was characterized using scanning electron microscopy (SEM) and Raman spectroscopy. PMID:26838911

  4. Controlled Release of Simvastatin from Biomimetic β-TCP Drug Delivery System

    PubMed Central

    Chou, Joshua; Ito, Tomoko; Bishop, David; Otsuka, Makoto; Ben-Nissan, Besim; Milthorpe, Bruce

    2013-01-01

    Simvastatin have been shown to induce bone formation and there is currently a urgent need to develop an appropriate delivery system to sustain the release of the drug to increase therapeutic efficacy whilst reducing side effects. In this study, a novel drug delivery system for simvastatin by means of hydrothermally converting marine exoskeletons to biocompatible beta-tricalcium phosphate was investigated. Furthermore, the release of simvastatin was controlled by the addition of an outer apatite coating layer. The samples were characterized by x-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and mass spectroscopy confirming the conversion process. The in-vitro dissolution of key chemical compositional elements and the release of simvastatin were measured in simulated body fluid solution showing controlled release with reduction of approximately 25% compared with un-coated samples. This study shows the potential applications of marine structures as a drug delivery system for simvastatin. PMID:23349949

  5. Formulation Optimization of Hydrodynamically Balanced Oral Controlled Release Bioadhesive Tablets of Tramadol Hydrochloride

    PubMed Central

    Singh, Bhupinder; Rani, Ashu; Babita; Ahuja, Naveen; Kapil, Rishi

    2010-01-01

    The directly compressible floating-bioadhesive tablets of tramadol were formulated using varying amounts Carbopol 971P (CP) and hydroxy-propylmethyl cellulose (HPMC), along with other requisite excipients. In vitro drug release profile, floatational characteristics and ex vivo bioadhesive strength using texture analyzer were determined, and systematically optimized using a 32 central composite design (CCD). The studies indicated successful formulation of gastroretentive compressed matrices with excellent controlled release, mucoadhesion and hydrodynamic balance. Comparison of the dissolution profiles of the optimized formulation, with optimal composition of CP:HPMC :: 80.0:125.0, with that of the marketed controlled release formulation other indicated analogy of drug release performance with each other. Validation of optimization study using eight confirmatory experimental runs indicated very high degree of prognostic ability of CCD with mean ± SEM of −0.06% ± 0.37. Further, the study successfully unravels the effect of the polymers on the selected response variables. PMID:21179349

  6. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  7. Core-Shell Electrospun Fibers Encapsulating Chromophores or Luminescent Proteins for Microscopically Controlled Molecular Release.

    PubMed

    Romano, Luigi; Camposeo, Andrea; Manco, Rita; Moffa, Maria; Pisignano, Dario

    2016-03-01

    Core-shell fibers are emerging as interesting microstructures for the controlled release of drugs, proteins, and complex biological molecules, enabling the fine control of microreservoirs of encapsulated active agents, of the release kinetics, and of the localized delivery. Here we load luminescent molecules and enhanced green fluorescent proteins into the core of fibers realized by coaxial electrospinning. Photoluminescence spectroscopy evidences unaltered molecular emission following encapsulation and release. Moreover, the release kinetics is microscopically investigated by confocal analysis at individual-fiber scale, unveiling different characteristic time scales for diffusional translocation at the core and at the shell. These results are interpreted by a two stage desorption model for the coaxial microstructure, and they are relevant in the design and development of efficient fibrous systems for the delivery of functional biomolecules. PMID:26870885

  8. Controlled release formulations of Atrazine and Mesotrione: characterization and sorption on soils

    NASA Astrophysics Data System (ADS)

    Pinheiro Dick, D.; Gomes de Ávila, L.; Benvenuti Leite, S.; Raffin Pohlmann, A.

    2009-04-01

    herbicides release from the formulations and from the commercial products in CaCl2 0,01 mol.L-1 medium was quantified by UV/vis spectroscopy along 24 hours. Mathematical models were tested in order to establish the release kinetics. Sorption isotherms of the formulations SGATZ150 and of the SGMES150 and of the comercial products were determined in three types of soil. The ATZ yields in the formulations were around 60%, while for MES the values reached 80%. In all formulations, ATZ was physically dispersed on the Si-polymer, and the dispersion grade decreased with increasing amount of added herbicide. The same behaviour was shown by MES. Both dissolution and diffusion processes controlled the release kinetics of ATZ from the formulations, whose data was fitted to the Korsmeyer-Peppas model. With the decrease of ATZ dispersion, the mechanism of dissolution assumes a more important role. In the case of MES, the dissolution to the aqueous media was rapidly achieved and the hebiced was located mostly outside the carrier polymer. Nevertheles, both herbicides in the form of xerogel presented a lower affinity for soil than in the commercial form. However, in soils with high contents of organic matter, the retention of ATZ in high affinity sorptive sites occurs both with the herbicide in molecular form as well as bound to the sol-gel matrix.

  9. A Cryptographic Framework for the Controlled Release Of Certified Data

    NASA Astrophysics Data System (ADS)

    Bangerter, Endre; Camenisch, Jan; Lysyanskaya, Anna

    The problem of privacy protection is to control the dissemination of personal data. There exist various privacy principles that describe at a conceptual level what measures have to be taken to protect privacy. Examples of these principles are an individual's right to access and to request correction of data about oneself and the requirement for an individual to consent to the disclosure of her personal data. Another principle is that of data minimization: It states that an individual should only disclose the minimal necessary data for a given purpose. Determining these data is often a difficult task, and one usually needs to balance an individual's privacy interests and the legitimate interest of other parties in the individual's data. An example of this trade-off is an individual's wish to be anonymous conflicting with her requirements imposed by law enforcement to be able to identify and get hold of criminals. Such trade-offs impose limits on privacy that cannot be overcome by any technology.

  10. Polysaccharide-based nanocomplexes for co-encapsulation and controlled release of 5-Fluorouracil and Temozolomide.

    PubMed

    Di Martino, Antonio; Pavelkova, Alena; Maciulyte, Sandra; Budriene, Saulute; Sedlarik, Vladimir

    2016-09-20

    Polysaccharide-based nanocomplexes, intended for simultaneous encapsulation and controlled release of 5-Fluorouracil (5-FU) and Temozolomide (TMZ) were developed via the complexation method using chitosan, alginic and polygalacturonic acid. Investigation focused on the influence of polysaccharides on the properties of the system and amelioration of the stability of the drugs, in particular TMZ. The dimensions of particles and their ζ-potential were found to range between 100 and 200nm and -25 to +40mV, respectively. Encapsulation efficiency varied from 16% to over 70%, depending on the given system. The influence of pH on the release and co-release of TMZ and 5-FU was evaluated under different pH conditions. The stability of the loaded drug, in particular TMZ, after release was evaluated and confirmed by LC-MS analysis. Results suggested that the amount of loaded drug(s) and the release rate is connected with the weight ratio of polysaccharides and the pH of the media. One-way ANOVA analysis on the obtained data revealed no interference between the drugs during the encapsulation and release process, and in particular no hydrolysis of TMZ occurred suggesting that CS-ALG and CS-PGA would represent interesting carriers for multi-drug controlled release and drugs protection. PMID:27154260

  11. Multiunit controlled-release diclofenac sodium capsules using complex of chitosan with sodium alginate or pectin.

    PubMed

    Mitrevej, A; Sinchaipanid, N; Rungvejhavuttivittaya, Y; Kositchaiyong, V

    2001-08-01

    This study explored the application of chitosan-alginate (CA) and chitosan-pectin (CP) complex films as drug release regulator for the preparation of multiunit controlled-release diclofenac sodium capsules. Pellets containing drug and microcrystalline cellulose, in a ratio of 3:5, were prepared in a fluidized rotary granulator. The pellets were coated with CA, CP, sodium alginate, pectin, and chitosan solutions. The pellets, equivalent to 75 mg drug, were filled into capsules. After 2 h of dissolution test in acidic medium, the amount of the drug released from any preparation was negligible. The pellets were further subject to pH 6.8 phosphate buffer More than 80% drug release at 12 h was observed with the uncoated pellets and those coated with sodium alginate, pectin or chitosan. Both 1% CA and 3% CP coated pellets exhibited drug release profiles similar to that of Voltaren SR75. It was found that approximately 60% and 85% of the drug were released at 12 and 24 h, respectively. Both Differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR) analyses revealed complex formation between chitosan and these anionic polymers. It could be concluded that CA and CP complex film could be easily applied to diclofenac sodium pellets to control the release of the drug. PMID:11485180

  12. Drug release control and system understanding of sucrose esters matrix tablets by artificial neural networks.

    PubMed

    Chansanroj, Krisanin; Petrović, Jelena; Ibrić, Svetlana; Betz, Gabriele

    2011-10-01

    Artificial neural networks (ANNs) were applied for system understanding and prediction of drug release properties from direct compacted matrix tablets using sucrose esters (SEs) as matrix-forming agents for controlled release of a highly water soluble drug, metoprolol tartrate. Complexity of the system was presented through the effects of SE concentration and tablet porosity at various hydrophilic-lipophilic balance (HLB) values of SEs ranging from 0 to 16. Both effects contributed to release behaviors especially in the system containing hydrophilic SEs where swelling phenomena occurred. A self-organizing map neural network (SOM) was applied for visualizing interrelation among the variables and multilayer perceptron neural networks (MLPs) were employed to generalize the system and predict the drug release properties based on HLB value and concentration of SEs and tablet properties, i.e., tablet porosity, volume and tensile strength. Accurate prediction was obtained after systematically optimizing network performance based on learning algorithm of MLP. Drug release was mainly attributed to the effects of SEs, tablet volume and tensile strength in multi-dimensional interrelation whereas tablet porosity gave a small impact. Ability of system generalization and accurate prediction of the drug release properties proves the validity of SOM and MLPs for the formulation modeling of direct compacted matrix tablets containing controlled release agents of different material properties. PMID:21878388

  13. Cyclodextrin multicomponent complexation and controlled release delivery strategies to optimize the oral bioavailability of vinpocetine.

    PubMed

    Ribeiro, Laura S S; Falcão, Amílcar C; Patrício, João A B; Ferreira, Domingos C; Veiga, Francisco J B

    2007-08-01

    In the present work, to maintain a suitable blood level of vinpocetine (VP) for a long period of time, VP-cyclodextrin-tartaric acid multicomponent complexes were prepared and formulated in hydroxypropylmethylcellulose matrix tablets. In vitro and in vivo performances of these formulations were investigated over a VP immediate release dosage form. Solubility studies were performed to evaluate the drug pH solubilization profile and to assess the effect of multicomponent complexation on VP solubility. The drug release process was investigated using United States Pharmacopeia apparatus 3 and a comparative oral pharmacokinetic study was subsequently undertaken in rabbits. Solubility studies denoted the pH-solubility dependence of VP and solubility improvement attained by complexation. Dissolution results showed controlled and almost complete release behavior of VP over a 12-h period from complex hydroxypropylmethylcellulose-based formulations. A clear difference between the pharmacokinetic patterns of VP immediate release and VP complex-based formulations was revealed. The area under the plasma concentration-time curve after oral administration of complex-based formulations was 2.1-2.9 times higher than that for VP immediate release formulation. Furthermore, significant differences found for mean residence time, elimination half-life, and elimination rate constant values corroborated prolonged release of VP from complex-based formulations. These results suggest that the oral bioavailability of VP was significantly improved by both multicomponent complexation and controlled release delivery strategies. PMID:17530626

  14. Formulation and evaluation of gastroretentive controlled release tablets of alfuzosin hydrochloride.

    PubMed

    Rudraswamy-Math, Nijaguni Revansiddayya; Gupta, Vankdari Rama-Mohan

    2015-11-01

    Alfuzosin hydrochloride is a novel drug used in the treatment of urinary incontinency. The purpose of this research was to develop controlled release floating matrix formulations of Alfuzosin HCl. Floating matrix tablets of Alfuzosin HCl were prepared using hydroxypropyl methylcellulose (HPMC), Polyethylene oxide (PEO), Carbopol 971P NF polymer (Direct compressible) and Blend of Polyvinyl Acetate and Povidone 30 (80:19:1(0.8% sodium laury sulfate and 0.2% silica)). Combination of citric acid and sodium bicarbonate were also used as gas forming agent. Matrix formulations were prepared by direct compression method and evaluated for floating, in vitro drug release profile and swelling characteristics. The mechanism of drug release was found to follow non-Fickian or anomalous type. The data obtained from the invitro release studies demonstrated that the floating matrix tablets containing HPMC 100K CR (controlled-release) and carbopol along with sodium CMC were found to sustain the release of drug over a period of 12 hours. Formulations containing 25% PEO 303WSR was also capable of sustaining delivery the release of Alfuzosin HCl. PMID:26639508

  15. Starch-based hydrogel loading with carbendazim for controlled-release and water absorption.

    PubMed

    Bai, Chan; Zhang, Sufen; Huang, Lei; Wang, Haiyan; Wang, Wei; Ye, Qingfu

    2015-07-10

    Starch, with properties of eco-friendliness and abundance, is one of the most important natural polymers. Starch-based hydrogels were investigated as carriers of carbendazim to combine controlled-release and water absorption (WA). Three carbendazim-loaded hydrogels (CLHs) with different WA capacities were prepared by solution polymerization. The CLHs were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and liquid-chromatography mass-spectrometry (LC-MS/MS). Release kinetics of CLHs was investigated using (14)C-labeling method. The diffusion parameters of CLHs were 0.47, 0.57 and 0.81 in deionized H2O (ddH2O). WA affected release profile significantly, the release longevity reaching 240 h when WA was 800 g/g in ddH2O. Solution pH influenced release profiles and the lowest release rate occurred in the lowest pH. Addition of CLH (1.3g/kg soil) markedly increased water-holding capacity (WHC) of soil by 8.2%. The study indicated that starch-based CLH was a good controlled-release agent for carbendazim and water absorbent for soil. PMID:25857995

  16. Control of photo-induced drug release by the use of conformational change of DNA.

    PubMed

    Tanabe, Kazuhito; Inasaki, Takeshi; Okamoto, Akimitsu; Nishimoto, Sei-ichi; Saito, Isao

    2002-01-01

    Photo-induced drug release system which was controlled by triplet quenching using the molecular beacon strategy of photoreactive oligodeoxynucleotides (P-ODN) was developed. The strand ends of P-ODN were modified with a phenacyl ester of biotin and naphthalene as photoreactive group and triplet quencher, respectively. Photoirradiation to P-ODN in the presence of complementary DNA caused an efficient release of biotin. In contrast, the biotin release was suppressed in the absence of complementary DNA by the intramolecular triplet quenching in the stem-and-loop structure of P-ODN. PMID:12903158

  17. Supercritical fluid extraction-liquid chromatography method development for a polymeric controlled-release drug formulation.

    PubMed

    Roston, D A; Sun, J J; Collins, P W; Perkins, W E; Tremont, S J

    1995-11-01

    We have recently been involved in the development of a method for assaying the active component in a controlled-release drug formulation, which is composed of a drug substance covalently bonded to polymer matrix. The drug substance in the formulation is the active enantiomer of misoprostol, a synthetic analog of natural prostaglandins and the active ingredient in Cytotec. Our method development consisted of a systematic evaluation of dynamic, off-line supercritical fluid extraction (SFE) as sample preparation for the formulation assay. Extracts were analyzed with normal phase and reversed-phase HPLC methods. The reversed-phase system utilized postcolumn reaction to provide selective detection of the extracted prostaglandin sample components. Several SFE parameters were investigated to optimize the recovery of the drug substance from the formulation, including sample quantity, extraction cell volume, extraction duration, supercritical carbon dioxide modifier, temperature, pressure, and collection solvent. The SFE experiments were completed with a commercially available multicell extractor. Preliminary validation studies utilized a formulation made with radiolabeled drug to determine the recovery achieved under the optimized SFE conditions and assessed the precision of replicate determinations. Analysis was completed under the optimized conditions to quantitate levels of the active component and related compounds in lots of the experimental polymeric formulation and to determine the total weight per cent extracted. PMID:8788137

  18. Development of patches for the controlled release of dehydroepiandrosterone.

    PubMed

    Minghetti, P; Cilurzo, F; Casiraghi, A; Montanari, L; Santoro, A

    2001-08-01

    Dehydroepiandrosterone (DHEA) and its sulfate conjugate (DHEAS) are the major secretory steroidal products of the adrenal gland. Some epidemiologic studies have found an association between low DHEA serum levels in patients and many important diseases. To prevent all such pathological conditions and, in any case, in aging, a DHEA supplementation has been proposed. DHEA shows a low oral bioavailability; taking the bioavailability obtained by the subcutaneous route as 100%, it was estimated that the potencies of DHEA by the percutaneous and oral routes were approximately 33% and 3%, respectively. Thus, transdermal patches could be considered a promising formulation as a continuous and controlled delivery of DHEA in replacement therapy is desired. With the aim of evaluating the effect of the matrix composition in terms of polymers and enhancers on the DHEA skin permeation flux, 10 types of monolayer self-adhesive patches containing 0.25mg/cm2 of active ingredient were designed. The matrices were based on three different acrylic copolymers: an acrylate-vinylacetate copolymer, a polyaminomethylmethacrylate (PAMA), and a polymethylmethacrylate. Transcutol (TR), mint essential oil, Lauroglycol, Brij 58, and propylene glycol (PG) were evaluated as DHEA skin permeation enhancers. All prepared patches were characterized by drug content, light microscopy, and in vitro skin permeation, performed using a modified Franz-type diffusion cell and human stratum corneum and epidermis as a membrane. The in vitro skin permeation studies are particularly significant in the development studies of DHEA patches as the in vivo determination of DHEA is affected b the fact that the endogen substance in the plasma is not constant over time. Among the testedpatches, highest DHEA fluxes were obtained using the formulation based on PAMA. Moreover, the introduction in the matrix of binary mixtures of TR and PG, used also for their plasticizer properties, permitted enhancing DHEA skin permeation

  19. Immobilization and controlled release of β-galactosidase from chitosan-grafted hydrogels.

    PubMed

    Facin, Bruno R; Moret, Bruna; Baretta, Dilmar; Belfiore, Laurence A; Paulino, Alexandre T

    2015-07-15

    Chitosan-grafted hydrogels were employed for immobilization and controlled released of β-galactosidase. These hydrogels containing immobilized enzymes were employed to simulate the production of lactose-free food and controlled release of β-galactosidase into lactose-intolerant individuals. The degree of swelling, efficiency of immobilization (i.e., fractional uptake of enzyme), and controlled release were studied as a function of pH and temperature. The degrees of swelling decreased in acidic media: 49.4 g absorbed water per g hydrogel at pH 7.0, and 8.4 g absorbed water per g hydrogel at pH 3.5. The immobilization efficiency was 19%, indicating that chitosan-grafted hydrogels are promising matrices for enzyme adsorption and immobilization. Cyclic experiments reveal that chitosan-grafted hydrogels containing immobilized enzymes can be reused several times without introducing additional enzyme prior to each cycle. There is no significant decrease in the activity of the immobilized enzyme during reutilization studies. All results were conducted in triplicate by considering t-tests at a 95% significance level. Analysis of β-galactosidase activity and controlled release reveals that chitosan-grafted hydrogels containing immobilized enzymes are useful for the production of lactose-free food and controlled enzyme release with high performance. PMID:25722137

  20. Dot Display Affects Approximate Number System Acuity and Relationships with Mathematical Achievement and Inhibitory Control

    PubMed Central

    Norris, Jade Eloise; Castronovo, Julie

    2016-01-01

    Much research has investigated the relationship between the Approximate Number System (ANS) and mathematical achievement, with continued debate surrounding the existence of such a link. The use of different stimulus displays may account for discrepancies in the findings. Indeed, closer scrutiny of the literature suggests that studies supporting a link between ANS acuity and mathematical achievement in adults have mostly measured the ANS using spatially intermixed displays (e.g. of blue and yellow dots), whereas those failing to replicate a link have primarily used spatially separated dot displays. The current study directly compared ANS acuity when using intermixed or separate dots, investigating how such methodological variation mediated the relationship between ANS acuity and mathematical achievement. ANS acuity was poorer and less reliable when measured with intermixed displays, with performance during both conditions related to inhibitory control. Crucially, mathematical achievement was significantly related to ANS accuracy difference (accuracy on congruent trials minus accuracy on incongruent trials) when measured with intermixed displays, but not with separate displays. The findings indicate that methodological variation affects ANS acuity outcomes, as well as the apparent relationship between the ANS and mathematical achievement. Moreover, the current study highlights the problem of low reliabilities of ANS measures. Further research is required to construct ANS measures with improved reliability, and to understand which processes may be responsible for the increased likelihood of finding a correlation between the ANS and mathematical achievement when using intermixed displays. PMID:27195749

  1. Functionalized Mesoporous Silica via an Aminosilane Surfactant Ion Exchange Reaction: Controlled Scaffold Design and Nitric Oxide Release

    PubMed Central

    2015-01-01

    Nitric oxide-releasing mesoporous silica nanoparticles (MSNs) were prepared using an aminosilane-template surfactant ion exchange reaction. Initially, bare silica particles were synthesized under basic conditions in the presence of cetyltrimethylammonium bromide (CTAB). These particles were functionalized with nitric oxide (NO) donor precursors (i.e., secondary amines) via the addition of aminosilane directly to the particle sol and a commensurate ion exchange reaction between the cationic aminosilanes and CTAB. N-Diazeniumdiolate NO donors were formed at the secondary amines to yield NO-releasing MSNs. Tuning of the ion exchange-based MSN modification approach allowed for the preparation of monodisperse particles ranging from 30 to 1100 nm. Regardless of size, the MSNs stored appreciable levels of NO (0.4–1.5 μmol mg–1) with tunable NO release durations (1–33 h) dependent on the aminosilane modification. Independent control of NO release properties and particle size was achieved, demonstrating the flexibility of this novel MSN synthesis over conventional co-condensation and surface grafting strategies. PMID:26717238

  2. Optimising the controlled release of dexamethasone from a new generation of PLGA-based microspheres intended for intravitreal administration.

    PubMed

    Rodríguez Villanueva, Javier; Bravo-Osuna, Irene; Herrero-Vanrell, Rocío; Molina Martínez, Irene Teresa; Guzmán Navarro, Manuel

    2016-09-20

    Successful therapy for chronic diseases affecting the posterior segment of the eye requires sustained drug concentrations at the site of action for extended periods of time. To achieve this, it is necessary to use high systemic doses or frequent intraocular injections, both associated with serious adverse effects. In order to avoid these complications and improve patient's quality of life, an experimental study has been conducted on the preparation of a new generation of biodegradable poly(D,L-lactide-co-glycolide) (50:50) (PLGA) polymer microspheres (MSs) loaded with Dxm, vitamin E and/or human serum albumin (HSA). Particles were prepared according to a S/O/W encapsulation method and the 20-40μm fraction was selected. This narrow size distribution is suitable for minimally invasive intravitreal injection by small calibre needles. Characterisation of the MSs showed high Dxm loading and encapsulation efficiency (> 90%) without a strong interaction with the polymer matrix, as revealed by DSC analysis. MSs drug release studies indicated a small burst effect (lower than 5%) during the first five hours and subsequently, drug release was sustained for at least 30days, led by diffusion and erosion mechanisms. Dxm release rate was modulated when solid state HSA was incorporated into MSs formulation. SDS-PAGE analysis showed that the protein maintained its integrity during the encapsulation process, as well as for the release study. MSs presented good tolerance and lack of cytotoxicity in macrophages and HeLa cultured cells. After 12months of storage under standard refrigerated conditions (4±1°C), MSs retained appropriate physical and chemical properties and analogous drug release kinetics. Therefore, we conclude that these microspheres are promising pharmaceutical systems for intraocular administration, allowing controlled release of the drug. PMID:26987610

  3. High-Achieving High School Students and Not so High-Achieving College Students: A Look at Lack of Self-Control, Academic Ability, and Performance in College

    ERIC Educational Resources Information Center

    Honken, Nora B.; Ralston, Patricia A. S.

    2013-01-01

    This study investigated the relationship among lack of self-control, academic ability, and academic performance for a cohort of freshman engineering students who were, with a few exceptions, extremely high achievers in high school. Structural equation modeling analysis led to the conclusion that lack of self-control in high school, as measured by…

  4. Timing of hatching and release of larvae by brachyuran crabs: patterns, adaptive significance and control.

    PubMed

    Christy, John H

    2011-07-01

    Most semiterrestrial, intertidal and shallow subtidal brachyuran crabs that live in tropical and warm temperate estuaries, bays and protected coasts world-wide release their planktonic larvae near the times of nocturnal high tides on the larger amplitude tides in the biweekly or monthly cycles of tidal amplitude. Crab larvae usually emigrate quickly to the sea where they develop to return as postlarvae to settle in habitats suitable for their survival. Predators of larvae are more abundant where larvae are released than where they develop, suggesting that this migration from estuaries to the sea reduces predation on larvae. Crabs with larvae that are relatively well-protected by spines and cryptic colors do not emigrate and often lack strong reproductive cycles, lending support to this explanation. Adults control the timing of the release of larvae with respect to the biweekly and monthly cycles of tidal amplitude by controlling when they court and mate and females control when development begins by controlling when they ovulate and allow their eggs to be fertilized by stored sperm. By changing the time they breed, fiddler crabs (Uca terpsichores) compensate for the effects of spatial and temporal variation in incubation temperature on development rates so that embryos are ready to hatch at the appropriate time. Control of the diel and tidal timing of hatching and of release of larvae varies with where adults live. Females of the more terrestrial species often move from protected incubation sites, sometimes far from water, and they largely control the precise time, both, of hatching and of release of larvae. Females of intertidal species also may influence when embryos begin to hatch. Upon hatching, a chemical cue is released that stimulates the female to pump her abdomen, causing rapid hatching and release of all larvae in her clutch. Embryos, rather than females, largely control hatching in subtidal species, perhaps because females incubate their eggs where they

  5. High school students' perceptions of EFL teacher control orientations and their English academic achievement.

    PubMed

    Kiany, Gholam Reza; Shayestefar, Parvaneh

    2011-09-01

    BACKGROUND. Theories distinguish between student-initiated and teacher-initiated regulation of students' learning activities, or between strong, shared, or loose teacher control during the completion of learning tasks. Empirical validations for such distinctions are scarce, however. AIM. The present study aimed at (a) investigating students' perceptions of control behaviours exhibited by their English teachers; and (b) exploring the contribution of different types of teacher control behaviours to students' cognitive outcomes (English Achievement). SAMPLE. The sample comprised 732 English as a Foreign Language (EFL) students studying in three major fields of high school (Mathematics, Natural Science, and Humanities). The participants (16-17 years of age) were selected from third-grade classes of 27 EFL teachers working in 25 high schools of 6 main different geographical regions in the Isfahan province, Iran. METHOD. To obtain a comprehensive picture of different control types exhibited by Iranian EFL teachers, the control subscales of the two existing questionnaires, i.e., the Questionnaire on Instructional Behaviours (QIB), adapted by Den Brok et al. (2004) and the Questionnaire on Lesson Activities (QLA) used by Den Brok (2001) were merged to form the Questionnaire of Teacher Control (QTC). The development of this Persian instrument involved several steps: translation and back translation by the researchers, one expert translator, and two EFL teachers; piloting; and a final administration of the questionnaire to the student sample. With respect to the second aim of the study, data regarding students' performances on the Standardized National English Achievement Tests were gathered from local educational offices and schools. RESULTS AND CONCLUSION. Statistical analyses supported acceptable reliability and validity of the instrument. A main factor structure with three types of teacher control (strong/high, shared/mid, and loose/low) was found to underlie students

  6. Distinct presynaptic control of dopamine release in striosomal and matrix areas of the cat caudate nucleus

    SciTech Connect

    Kemel, M.L.; Desban, M.; Glowinski, J.; Gauchy, C. )

    1989-11-01

    By use of a sensitive in vitro microsuperfusion method, the cholinergic presynaptic control of dopamine release was investigated in a prominent striosome (areas poor in acetylcholinesterase activity) located within the core of cat caudate nucleus and also in adjacent matrix area. The spontaneous release of ({sup 3}H)dopamine continuously synthesized from ({sup 3}H)tyrosine in the matrix area was found to be twice that in the striosomal area; the spontaneous and potassium-evoked releases of ({sup 3}H)dopamine were calcium-dependent in both compartments. With 10{sup {minus}6} M tetrodotoxin, 5 {times} 10{sup {minus}5} M acetylcholine stimulated ({sup 3}H)dopamine release in both striosomal and matrix areas, effects completely antagonized by atropine, thus showing the involvement of muscarinic receptors located on dopaminergic nerve terminals. Experiments without tetrodotoxin revealed a more complex regulation of dopamine release in the matrix: (i) in contrast to results seen in the striosome, acetylcholine induced only a transient stimulatory effect on matrix dopamine release. (ii) Although 10{sup {minus}6} M atropine completely abolished the cholinergic stimulatory effect on ({sup 3}H)dopamine release in striosomal area, delayed and prolonged stimulation of ({sup 3}H) dopamine release was seen with atropine in the matrix. The latter effect was completely abolished by the nicotinic antagonist pempidine. Therefore, in the matrix, in addition to its direct (tetrodotoxin-insensitive) facilitatory action on ({sup 3}H)dopamine release, acetylcholine exerts two indirect (tetrodotoxin-sensitive) opposing effects: an inhibition and a stimulation of ({sup 3}H)dopamine release mediated by muscarinic and nicotinic receptors, respectively.

  7. PCL-forsterite nanocomposite fibrous membranes for controlled release of dexamethasone.

    PubMed

    Kharaziha, Mahshid; Fathi, Mohammad Hossein; Edris, Hossein; Nourbakhsh, Nosrat; Talebi, Ardeshir; Salmanizadeh, Sharareh

    2015-01-01

    The well-known treatment of the alveolar bone defects is guided tissue regeneration (GTR). Engineered membranes combined with osteo-differentiation factors have been offered a promising strategy for GTR application. Recently, poly(ε-caprolactone) (PCL)-forsterite (PCL-F) nanocomposite fibrous membranes have been developed. However, PCL-F membranes could not promote bone tissue regeneration. The aim of this research is to encapsulate an osteogenic factor [dexamethasone (DEX)] in PCL-F membranes and evaluate the effects of forsterite nanopowder (particle size = 25-45 nm) and fiber organization on DEX delivery for GTR application. The hypothesis is that the release kinetic and profile of DEX could be controlled through variation of forsterite content (0, 5 and 10 wt%) and fiber arrangement (aligned and random). Results demonstrated while DEX release was sustained over a period of 4 weeks, its kinetic was governed by the membrane architecture and composition. For example, aligned PCL-F nanocomposite fibrous membrane consisting of 10 %(w/v) forsterite nanopowder exhibited the least initial burst release (13 % release in the first 12 h) and allowed sustained release of DEX. Additionally, forsterite nanopowder inclusion changed the kinetic of DEX release from Fickian diffusion to an anomalous transport. The bioactivity of released DEX was estimated using culturing the stem cells from human exfoliated deciduous teeth (SHED) on the membranes. Results demonstrated that proliferation and osteogenic differentiation of SHED could be governed by DEX release process. While DEX release from the membranes decreased SHED proliferation, stimulated the matrix mineralization. Our finding indicated that aligned PCL-F/DEX membrane could be used as a carrier for the sustained release of drugs relevant for GTR trophy. PMID:25578712

  8. Preparation and Physicochemical Evaluation of Controlled-release Carbon Source Tablet for Groundwater in situ Denitrification

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kang, J. H.; Yeum, Y.; Han, K. J.; Kim, D. W.; Park, C. W.

    2015-12-01

    Nitric nitrogen could be the one of typical pollution source such asNO3-through domestic sewage, livestock and agricultural wastewater. Resident microflorain aquifer has known to remove the nitric nitrogen spontaneously following the denitration process with the carbon source (CS) as reactant. However, it could be reacted very slowly with the rack of CS and there have been some studies for controlled addition of CS (Ref #1-3). The aim of this study was to prepare the controlled-release carbon source (CR-CS) tablet and to evaluate in vitro release profile for groundwater in situ denitrification. CR-CS tablet could be manufactured by direct compression method using hydraulic laboratory press (Caver® 3850) with 8 mm rounded concave punch/ die.Seven kinds of CR-CS tablet were prepared to determine the nature of the additives and their ratio such as sodium silicate, dicalcium phosphate, bentonite and sand#8.For each formulation, the LOD% and flowability of pre-mixed powders and the hardness of compressed tablets were analyzed. In vitro release study was performed to confirm the dissolution profiles following the USP Apparatus 2 method with Distilled water of 900mL, 20 °C. As a result, for each lubricated powders, they were compared in terms of ability to give an acceptable dry pre-mixed powder for tableting process. The hardness of the compressed tablets is acceptable whatever the formulations tested. After in vitro release study, it could confirm that the different formulations of CR-CS tablet have a various release rate patterns, which could release 100% at 3 hrs, 6 hrs and 12 hrs. The in vitro dissolution profiles were in good correlation of Higuchi release kinetic model. In conclusion, this study could be used as a background for development and evaluation of the controlled-release carbon source (CR-CS) tablet for the purification of groundwater following the in situ denitrification.

  9. Extracellular control of intracellular drug release for enhanced safety of anti-cancer chemotherapy

    NASA Astrophysics Data System (ADS)

    Zhu, Qian; Qi, Haixia; Long, Ziyan; Liu, Shang; Huang, Zhen; Zhang, Junfeng; Wang, Chunming; Dong, Lei

    2016-06-01

    The difficulty of controlling drug release at an intracellular level remains a key challenge for maximising drug safety and efficacy. We demonstrate herein a new, efficient and convenient approach to extracellularly control the intracellular release of doxorubicin (DOX), by designing a delivery system that harnesses the interactions between the system and a particular set of cellular machinery. By simply adding a small-molecule chemical into the cell medium, we could lower the release rate of DOX in the cytosol, and thereby increase its accumulation in the nuclei while decreasing its presence at mitochondria. Delivery of DOX with this system effectively prevented DOX-induced mitochondria damage that is the main mechanism of its toxicity, while exerting the maximum efficacy of this anti-cancer chemotherapeutic agent. The present study sheds light on the design of drug delivery systems for extracellular control of intracellular drug delivery, with immediate therapeutic implications.

  10. Application of photoremovable protecting group for controlled release of plant growth regulators by sunlight.

    PubMed

    Atta, Sanghamitra; Ikbal, Mohammed; Kumar, Ashutosh; Pradeep Singh, N D

    2012-06-01

    We report a novel technique for controlled release of plant growth regulators (PGRs) by sunlight using photoremovable protecting group (PRPG) as a delivery device. In the present work, carboxyl-containing PGRs of the auxin group [indoleacetic acid (IAA) and naphthoxyacetic acid (NOAA)] were chemically caged using PRPGs of coumarin derivatives. Photophysical studies showed that caged PGRs exhibited good fluorescence properties. Irradiation of caged PGRs by sunlight in both aqueous ethanol and soil media resulted in controlled release of PGRs. The results of the bioactivity experiments indicated that caged PGRs showed better enhancement in the root and shoot length growth of Cicer arietinum compared to PGRs after 10days of sunlight exposure. Our results indicated that use of PRPG as a delivery device for controlled release of PGRs by sunlight in soil holds great interest for field application since it can overcome the rapid loss of PGRs in environmental conditions. PMID:22513094

  11. Synthesis, characterization, and application of microbe-triggered controlled-release kasugamycin-pectin conjugate.

    PubMed

    Liu, Yao; Sun, Yan; Ding, Guanglong; Geng, Qianqian; Zhu, Juanli; Guo, Mingcheng; Duan, Yongheng; Wang, Baitao; Cao, Yongsong

    2015-05-01

    The controlled and targeted release of pesticides with high water solubility has been a challenge for integrated pest management. In this paper, kasugamycin, an antibiotic broadly used in plant disease control, was covalently conjugated to pectin to form a kasugamycin-pectin conjugate by an amide bond. The conjugate was structurally characterized by Fourier transform infrared spectroscopy, ultraviolet spectrophotometry, and thermal gravimetric analysis. The results showed that the conjugate was stable over a wide range of pH and temperatures, as well as under UV irradiation. When incubated with Pseudomonas syringae pv. lachrymans, the conjugate could be activated, releasing the kasugamycin, which made it a promising controlled-release formulation of pesticide. PMID:25876441

  12. Extracellular control of intracellular drug release for enhanced safety of anti-cancer chemotherapy

    PubMed Central

    Zhu, Qian; Qi, Haixia; Long, Ziyan; Liu, Shang; Huang, Zhen; Zhang, Junfeng; Wang, Chunming; Dong, Lei

    2016-01-01

    The difficulty of controlling drug release at an intracellular level remains a key challenge for maximising drug safety and efficacy. We demonstrate herein a new, efficient and convenient approach to extracellularly control the intracellular release of doxorubicin (DOX), by designing a delivery system that harnesses the interactions between the system and a particular set of cellular machinery. By simply adding a small-molecule chemical into the cell medium, we could lower the release rate of DOX in the cytosol, and thereby increase its accumulation in the nuclei while decreasing its presence at mitochondria. Delivery of DOX with this system effectively prevented DOX-induced mitochondria damage that is the main mechanism of its toxicity, while exerting the maximum efficacy of this anti-cancer chemotherapeutic agent. The present study sheds light on the design of drug delivery systems for extracellular control of intracellular drug delivery, with immediate therapeutic implications. PMID:27334142

  13. A novel graphene nanodots inlaid porous gold electrode for electrochemically controlled drug release.

    PubMed

    Wang, Jianmei; Yang, Peng; Cao, Mengmei; Kong, Na; Yang, Wenrong; Sun, Shu; Meng, You; Liu, Jingquan

    2016-01-15

    A uniform graphene nanodots inlaid porous gold electrode was prepared via ion beam sputtering deposition (IBSD) and mild corrosion chemistry. HRTEM, SEM, AFM and XPS analyses revealed the successful fabrication of graphene nanodots inlaid porous gold electrode. The as-prepared porous electrode was used as π-orbital-rich drug loading platform to fabricate an electrochemically controlled drug release system with high performance. π-orbital-rich drugs with amino mioety, like doxorubicin (DOX) and tetracycline (TC), were loaded into the graphene nanodots inlaid porous gold electrode via non-covalent π-π stacking interaction. The amino groups in DOX and TC can be easily protonated at acidic medium to become positively-charged NH3(+), which allow these drug molecules to be desorbed from the porous electrode surface via electrostatic repulsion when positive potential is applied at the electrode. The drug loading and release experiment indicated that this graphene nanodots inlaid porous gold electrode can be used to conveniently and efficiently control the drug release electrochemically. Not only did our work provide a benign method to electrochemically controlled drug release via electrostatic repulsion process, it also enlighten the promising practical applications of micro electrode as a drug carrier for precisely and efficiently controlled drug release via embedding in the body. PMID:26592594

  14. Stability, bioavailability, and ulcerative activity of diclofenac sodium-mastic controlled release tablets.

    PubMed

    Nouh, A T; Abd El-Gawad, A H; Guda, T K

    2010-04-01

    Controlled release tablets containing 50 mg diclofenac sodium (DS) and 40% mastic with other natural additives were prepared. Drug release was examined and stability was studied using non-isothermal and isothermal thermogravimetric analysis (TGA). The bioavailability of two controlled release tablet formulations was studied and compared to that of commercial tablets, and rabbit stomachs were also histologically examined 24 h after administration of the various tablets. Additives of pectin and sodium alginate indicated the controlled release profile of the drug. Non-isothermal TG revealed two stages of thermal decomposition for all formulations. Isothermal TG revealed that degradation of the drug in the tablet formulations follows first-order kinetics. The obtained degradation rate constants at various temperatures were plotted according to the Arrhenius equation. The degradation rate constant at 25°C was determined and used in estimation of shelf life. The obtained shelf lives of all formulations ranged from 3.38-4.92 years. In comparative studies with commercial tablets, the bioavailability of the drug from the two formulated tablets had no statistically significant difference in terms of the AUC and produced prolonged blood levels of DS with a delayed peak. The two controlled release tablet formulations resulted in no histological alterations in the stomach in terms of mucous surface cells and glands; in comparison, commercial tablets resulted in a disrupted mucous layer, necrotic ulcerations, hemorrhaging, and inflammatory cell infiltration along the base of the gastric glands. PMID:22491166

  15. Polydopamine film coated controlled-release multielement compound fertilizer based on mussel-inspired chemistry.

    PubMed

    Jia, Xin; Ma, Zhi-yuan; Zhang, Guo-xiang; Hu, Jia-mei; Liu, Zhi-yong; Wang, He-yun; Zhou, Feng

    2013-03-27

    This work reports on a facile and reliable method to prepare a polydopamine film coated controlled-release multielement compound fertilizer (PCMCF) based on mussel-inspired chemistry for the first time. The polydopamine (Pdop) film was coated on double copper potassium pyrophosphate trihydrate, providing three essential nutrients (Cu, K, and P) by spontaneous oxidative polymerization of dopamine. The thickness of the polymer coating of the fertilizer was controlled by using the multistep deposition technique. The morphology and composition of the products were characterized by transmission electron microscopy, inductively coupled plasma emission spectrometer, a vis spectrophotometer, and a Kjeltec autoanalyzer. The controlled-release behavior of four elements, including nitrogen from Pdop, was evaluated in water and in soil (sterilized or not). The results revealed that the coated fertilizers had good slow-release properties, incubated in either water or soil. It is noted that the release rate of nutrients of PCMCF can be tailored by the thickness of the Pdop coating, and the Pdop coating can be biodegraded in soil. This coating technology will be effective and promising in the research and development of controlled-release fertilizer. PMID:23464683

  16. Synthesis of bio-based nanocomposites for controlled release of antimicrobial agents in food packaging

    NASA Astrophysics Data System (ADS)

    DeGruson, Min Liu

    The utilization of bio-based polymers as packaging materials has attracted great attention in both scientific and industrial areas due to the non-renewable and nondegradable nature of synthetic plastic packaging. Polyhydroxyalkanoate (PHA) is a biobased polymer with excellent film-forming and coating properties, but exhibits brittleness, insufficient gas barrier properties, and poor thermal stability. The overall goal of the project was to develop the polyhydroxyalkanoate-based bio-nanocomposite films modified by antimicrobial agents with improved mechanical and gas barrier properties, along with a controlled release rate of antimicrobial agents for the inhibition of foodborne pathogens and fungi in food. The ability for antimicrobial agents to intercalate into layered double hydroxides depended on the nature of the antimicrobial agents, such as size, spatial structure, and polarity, etc. Benzoate and gallate anions were successfully intercalated into LDH in the present study and different amounts of benzoate anion were loaded into LDH under different reaction conditions. Incorporation of nanoparticles showed no significant effect on mechanical properties of polyhydroxybutyrate (PHB) films, however, significantly increased the tensile strength and elongation at break of polyhydroxybutyrate-co-valerate (PHBV) films. The effects of type and concentration of LDH nanoparticles (unmodified LDH and LDH modified by sodium benzoate and sodium gallate) on structure and properties of PHBV films were then studied. The arrangement of LDH in the bio-nanocomposite matrices ranged from exfoliated to phase-separated depending on the type and concentration of LDH nanoparticles. Intercalated or partially exfoliated structures were obtained using modified LDH, however, only phase-separated structures were formed using unmodified LDH. The mechanical (tensile strength and elongation at break) and thermo-mechanical (storage modulus) properties were significantly improved with low

  17. Environmental controls of greenhouse gas release in a restoring peat bog in NW Germany

    NASA Astrophysics Data System (ADS)

    Glatzel, S.; Forbrich, I.; Krüger, C.; Lemke, S.; Gerold, G.

    2008-01-01

    In Central Europe, most bogs have a history of drainage and many of them are currently being restored. Success of restoration as well as greenhouse gas exchange of these bogs is influenced by environmental stress factors as drought and atmospheric nitrogen deposition. We determined the methane and nitrous oxide exchange of sites in the strongly decomposed center and less decomposed edge of the Pietzmoor bog in NW Germany in 2004. Also, we examined the methane and nitrous oxide exchange of mesocosms from the center and edge before, during, and following a drainage experiment as well as carbon dioxide release from disturbed unfertilized and nitrogen fertilized surface peat. In the field, methane fluxes ranged from 0 to 3.8 mg m-2 h-1 and were highest from hollows. Field nitrous oxide fluxes ranged from 0 to 574 μg m-2 h-1 and were elevated at the edge. A large Eriophorum vaginatum tussock showed decreasing nitrous oxide release as the season progressed. Drainage of mesocosms decreased methane release to 0, even during rewetting. There was a tendency for a decrease of nitrous oxide release during drainage and for an increase in nitrous oxide release during rewetting. Nitrogen fertilization did not increase decomposition of surface peat. Our examinations suggest a competition between vascular vegetation and denitrifiers for excess nitrogen. We also provide evidence that the von Post humification index can be used to explain greenhouse gas release from bogs, if the role of vascular vegetation is also considered. An assessment of the greenhouse gas release from nitrogen saturated restoring bogs needs to take into account elevated release from fresh Sphagnum peat as well as from sedges growing on decomposed peat. Given the high atmospheric nitrogen deposition, restoration will not be able to achieve an oligotrophic ecosystem in the short term.

  18. How do different components of Effortful Control contribute to children’s mathematics achievement?

    PubMed Central

    Sánchez-Pérez, Noelia; Fuentes, Luis J.; Pina, Violeta; López-López, Jose A.; González-Salinas, Carmen

    2015-01-01

    This work sought to investigate the specific contribution of two different components of Effortful Control (EC) -attentional focusing (AF) and inhibitory control- to children’s mathematics achievement. The sample was composed of 142 children aged 9–12 year-old. EC components were measured through the Temperament in Middle Childhood Questionnaire (TMCQ; parent’s report); math achievement was measured via teacher’s report and through the standard Woodcock–Johnson test. Additionally, the contribution of other cognitive and socio-emotional processes was taken into account. Our results showed that only AF significantly contributed to the variance of children’s mathematics achievement; interestingly, mediational models showed that the relationship between effortful attentional self-regulation and mathematics achievement was mediated by academic peer popularity, as well as by intelligence and study skills. Results are discussed in the light of the current theories on the role of children’s self-regulation abilities in the context of school. PMID:26441758

  19. Professional training in the workplace: the role of achievement motivation and locus of control.

    PubMed

    Suárez-Álvarez, Javier; Campillo-Álvarez, Angela; Fonseca-Pedrero, Eduardo; García-Cueto, Eduardo; Muñiz, José

    2013-01-01

    The core objective of the present work is to explore the reasons why workers from different employment sectors join training courses to improve their job. To this end we assessed achievement motivation, locus of control and professional qualifications according to the participants' employment sector. The final sample consisted of 1460 active Spanish workers from four different employment sectors: services, catering, metal construction, and others. Of the sample, 40.1% were male and 59.9% female, with a mean age of 33.3 years (SD = 9.7). The results show that the new scale developed to assess achievement motivation, locus of control and workers' qualifications presents adequate psychometric characteristics. Statistically significant differences were found in relation to employment sector. The areas studied showed satisfactory levels of workers' effort and achievement motivation to perform their jobs, though their attitudes toward the training courses as a basis for improving their employability are varied. Workers in the catering sector had higher levels of external attribution and the lowest interest in training. Those in the service sector had higher levels of achievement motivation and effort at work. Future research should develop a joint program covering the public and private sectors for the modification of these beliefs, attitudes and attributions. PMID:23866230

  20. Controlled release of functional proteins through designer self-assembling peptide nanofiber hydrogel scaffold

    PubMed Central

    Koutsopoulos, Sotirios; Unsworth, Larry D.; Nagai, Yusuke; Zhang, Shuguang

    2009-01-01

    The release kinetics for a variety of proteins of a wide range of molecular mass, hydrodynamic radii, and isoelectric points through a nanofiber hydrogel scaffold consisting of designer self-assembling peptides were studied by using single-molecule fluorescence correlation spectroscopy (FCS). In contrast to classical diffusion experiments, the single-molecule approach allowed for the direct determination of diffusion coefficients for lysozyme, trypsin inhibitor, BSA, and IgG both inside the hydrogel and after being released into the solution. The results of the FCS analyses and the calculated pristine in-gel diffusion coefficients were compared with the values obtained from the Stokes–Einstein equation, Fickian diffusion models, and the literature. The release kinetics suggested that protein diffusion through nanofiber hydrogels depended primarily on the size of the protein. Protein diffusivities decreased, with increasing hydrogel nanofiber density providing a means of controlling the release kinetics. Secondary and tertiary structure analyses and biological assays of the released proteins showed that encapsulation and release did not affect the protein conformation and functionality. Our results show that this biocompatible and injectable designer self-assembling peptide hydrogel system may be useful as a carrier for therapeutic proteins for sustained release applications. PMID:19273853

  1. Molded polymer-coated composite bone void filler improves tobramycin controlled release kinetics.

    PubMed

    Brooks, Benjamin D; Sinclair, Kristofer D; Davidoff, Sherry N; Lawson, Scott; Williams, Alex G; Coats, Brittany; Grainger, David W; Brooks, Amanda E

    2014-07-01

    Infection remains a significant problem associated with biomedical implants and orthopedic surgeries, especially in revision total joint replacements. Recent advances in antibiotic-releasing bone void fillers (BVF) provide new opportunities to address these types of device-related orthopedic infections that often lead to substantial economic burdens and reduced quality of life. We report improvements made in fabrication and scalability of an antibiotic-releasing polycaprolactone-calcium carbonate/phosphate ceramic composite BVF using a new solvent-free, molten-cast fabrication process. This strategy provides the ability to tailor drug release kinetics from the BVF composite based on modifications of the inorganic substrate and/or the polymeric component, allowing extended tobramycin release at bactericidal concentrations. The mechanical properties of the new BVF composite are comparable to many reported BVFs and validate the relative homogeneity of fabrication. Most importantly, fabrication quality controls are correlated with favorable drug release kinetics, providing bactericidal activity to 10 weeks in vitro when the polycaprolactone component exceeds 98% w/w of the total polymer fraction. Furthermore, in a time kill study, tobramycin-releasing composite fragments inhibited S. aureus growth over 48 h at inoculums as high as 10(9) CFU/mL. This customizable antibiotic-releasing BVF polymer-inorganic biomaterial should provide osseointegrative and osteoconductive properties while contributing antimicrobial protection to orthopedic sites requiring the use of bone void fillers. PMID:24376164

  2. A repertoire of peptide tags for controlled drug release from injectable noncovalent hydrogel.

    PubMed

    Wieduwild, Robert; Lin, Weilin; Boden, Annett; Kretschmer, Karsten; Zhang, Yixin

    2014-06-01

    A repertoire of conjugable tags for controlling the release of drugs from biomaterials is highly interesting for the development of combinatorial drug administration techniques. This paper describes such a system of 11 peptide tags derived from our previous work on a physical hydrogel system cross-linked through peptide-heparin interactions. The release kinetics of the tags correlate well with their affinity to heparin and obey Fick's second law of diffusion, with the exception of the ATIII peptide, which displays a stable release profile close to a zero-order reaction. A system for release experiments over seven months was built, using the hydrogel matrix as a barrier between the reservoirs of tagged compounds and supernatant. The gel matrix can be injected without affecting the releasing properties. A tagged cyclosporin A derivative was also tested, and its release was monitored by measuring its biological activity. This work represents a design of biomaterials with an integral system of drug delivery, where both the assembly process of the matrix and affinity capture/release of tagged compounds are based on the noncovalent interaction of heparin with one class of peptides. PMID:24825401

  3. Chemical controls on abiotic and biotic release of geogenic arsenic from Pleistocene aquifer sediments to groundwater.

    PubMed

    Gillispie, Elizabeth C; Andujar, Erika; Polizzotto, Matthew L

    2016-08-10

    Over 150 million people in South and Southeast Asia consume unsafe drinking water from arsenic-rich Holocene aquifers. Although use of As-free water from Pleistocene aquifers is a potential mitigation strategy, such aquifers are vulnerable to geogenic As pollution, placing millions more people at potential risk. The goal of this research was to define chemical controls on abiotic and biotic release of geogenic As to groundwater. Batch incubations of sediments with natural chemical variability from a Pleistocene aquifer in Cambodia were conducted to evaluate how interactions among arsenic, manganese and iron oxides, and dissolved and sedimentary organic carbon influenced As mobilization from sediments. The addition of labile dissolved organic carbon produced the highest concentrations of dissolved As after >7 months, as compared to sediment samples incubated with sodium azide or without added carbon, and the extent of As release was positively correlated with the percent of initial extractable Mn released from the sediments. The mode of As release was impacted by the source of DOC supplied to the sediments, with biological processes responsible for 81% to 85% of the total As release following incubations with lactate and acetate but only up to 43% to 61% of the total As release following incubations with humic and fulvic acids. Overall, cycling of key redox-active elements and organic-carbon reactivity govern the potential for geogenic As release to groundwater, and results here may be used to formulate better predictions of the arsenic pollution potential of aquifers in South and Southeast Asia. PMID:27463026

  4. Perceived Control Mediates the Relations between Depressive Symptoms and Academic Achievement in Adolescence.

    PubMed

    Moè, Angelica

    2015-01-01

    The present research examined the protective role played by perceived control in the relation between depressive symptoms and academic achievement in adolescence. A sample of 218 adolescents aged 11 to 16 filled in questionnaires to assess self-reported depressive symptoms and three factors tied with Perceived Control (PC): self-regulated learning strategies use, effort attribution, and perceived competence. Grade Point Average (GPA) was considered as a measure of academic achievement. A path model showed that the relation between GPA and depressive symptoms is mediated by PC (p<.05), and became non-significant when PC is considered. The discussion stresses the need to take into account the strategic and motivational factors favouring learning in planning programmes to prevent and treat depressive symptoms in adolescence. PMID:26377348

  5. An Active Suspension Controller Achieving the Best Ride Comfort at Any Specified Location on A Vehicle

    NASA Astrophysics Data System (ADS)

    Oya, Masahiro; Harada, Hiroshi; Araki, Yoshiaki

    In this paper, a new active suspension control scheme is developed so that ride comfort becomes best at any specified location on vehicle body. To achieve this end, two ideal vehicles are designed in which ride comfort becomes best at each different location. Then, linearly combining the two ideal vehicles, a combined ideal vehicle is constructed. It should be noted that we can easily force ride comfort at a specified location become best in the proposed combined ideal vehicle by setting only one design parameter. To achieve the good property stated above in actual vehicles, a robust tracking controller is proposed. It is shown by carrying out numerical simulations that ride comfort at a specified location can be easily improved in the closed loop system using the proposed combined ideal vehicle.

  6. Synthetic Zeolites as Controlled-Release Delivery Systems for Anti-Inflammatory Drugs.

    PubMed

    Khodaverdi, Elham; Soleimani, Hossein Ali; Mohammadpour, Fatemeh; Hadizadeh, Farzin

    2016-06-01

    Scientists have always been trying to use artificial zeolites to make modified-release drug delivery systems in the gastrointestinal tract. An ideal carrier should have the capability to release the drug in the intestine, which is the main area of absorption. Zeolites are mineral aluminosilicate compounds with regular structure and huge porosity, which are available in natural and artificial forms. In this study, soaking, filtration and solvent evaporation methods were used to load the drugs after activation of the zeolites. Weight measurement, spectroscopy FTIR, thermogravimetry and scanning electronic microscope were used to determine drug loading on the systems. Finally, consideration of drug release was made in a simulated gastric fluid and a simulated intestinal fluid for all matrixes (zeolites containing drugs) and drugs without zeolites. Diclofenac sodium (D) and piroxicam (P) were used as the drug models, and zeolites X and Y as the carriers. Drug loading percentage showed that over 90% of drugs were loaded on zeolites. Dissolution tests in stomach pH environment showed that the control samples (drug without zeolite) released considerable amount of drugs (about 90%) within first 15 min when it was about 10-20% for the matrixes. These results are favorable as NSAIDs irritate the stomach wall and it is ideal not to release much drugs in the stomach. Furthermore, release rate of drugs from matrixes has shown slower rate in comparison with control samples in intestine pH environment. PMID:26705687

  7. Design and evaluation of osmotic pump-based controlled release system of Ambroxol Hydrochloride.

    PubMed

    Cheng, Xiongkai; Sun, Min; Gao, Yan; Cao, Fengliang; Zhai, Guangxi

    2011-08-01

    The purpose of the present study was to design and evaluate an osmotic pump-based drug delivery system for controlling the release of Ambroxol Hydrochloride (Amb). Citric acid, lactose and polyethylene glycol 6000 (PEG 6000) were employed as osmotic agents. Surelease EC containing polyethylene glycol 400 (PEG 400) controlling the membrane porosity was used as semi-permeable membrane. The formulation of tablet core was optimized by orthogonal design and evaluated by weighted mark method. The influences of the amount of PEG 400 and membrane thickness on Amb release were investigated. The optimal osmotic pump tablet (OPT) was evaluated in different release media and at different stirring rates. The major release power confirmed was osmotic pressure. The release of Amb from OPT was verified at a rate of approximately zero-order, and cumulative release percentage at 12?h was 92.6%. The relative bioavailability of Amb OPT in rabbits relative to the commercial sustained capsule was 109.6%. Our results showed that Amb OPT could be a practical preparation with a good prospect. PMID:20429827

  8. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    PubMed Central

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-01-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

  9. Photo-inducible Crosslinked Nanoassemblies for pH-Controlled Drug Release

    PubMed Central

    Dickerson, Matthew; Winquist, Nickolas; Bae, Younsoo

    2014-01-01

    Purpose To control drug release from block copolymer nanoassemblies by variation in the degree of photo-crosslinking and inclusion of acid sensitive linkers. Methods Poly(ethylene glycol)-poly(aspartate-hydrazide-cinnamate) (PEG-CNM) block copolymers were prepared and conjugated with a model drug, doxorubicin (DOX), through acid sensitive hydrazone linkers. The block copolymers formed photo-inducible, self-assembled nanoassemblies (piSNAs), which were used to produce photo-inducible crosslinked nanoassemblies (piCNAs) through UV crosslinking. The nanoassemblies were characterized to determine particle size, surface charge, pH- and crosslinking-dependent DOX release, in vitro cytotoxicity, and intracellular uptake as a function of photo-crosslinking degree. Results Nanoassemblies with varying photo-crosslinking degrees were successfully prepared while retaining particle size and surface charge. Photo-crosslinking caused no noticeable change in DOX release from the nanoassemblies at pH 7.4, but the DOX-loaded nanoassemblies modulated drug release as a function of crosslinking at pH 6.0. The nanoassemblies showed similar cytotoxicity regardless of crosslinking degrees, presumably due to the low cellular uptake and cell nucleus drug accumulation. Conclusion Photo-crosslinking is useful to control drug release from pH-sensitive block copolymer nanoassemblies as a function of crosslinking without altering the particle properties, and thus providing unique tools to investigate the pharmaceutical effects of drug release on cellular response. PMID:24254196

  10. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    DOE PAGESBeta

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-16

    In spite of the massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Here we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases, and we usemore » molecular simulations to demonstrate it. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Finally, our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.« less

  11. Nanostructural control of methane release in kerogen and its implications to wellbore production decline.

    PubMed

    Ho, Tuan Anh; Criscenti, Louise J; Wang, Yifeng

    2016-01-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

  12. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    NASA Astrophysics Data System (ADS)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  13. Chitosan coatings to control release and target tissues for therapeutic delivery.

    PubMed

    Jennings, Jessica Amber; Wells, Carlos Montez; McGraw, Gregory S; Velasquez Pulgarin, Diego A; Whitaker, Marsalas D; Pruitt, Reginald L; Bumgardner, Joel David

    2015-07-01

    The natural biopolymer chitosan has versatile applications in therapeutic delivery. Coating drug delivery matrices or biomaterials with chitosan offers several advantages in drug delivery, including control of drug release, slowing degradation rate and improving biocompatibility. Advanced uses of chitosan in coating form include targeting drug delivery vehicles to specific tissue as well as providing a stimulus-controlled release response. The present review summarizes the current applications of chitosan coatings in the context of different biomaterial delivery technologies, as well as future directions of chitosan coatings for drug delivery technologies under development. PMID:26228776

  14. Nanogels fabricated by lysozyme and sodium carboxymethyl cellulose for 5-fluorouracil controlled release.

    PubMed

    Zhu, Kunkun; Ye, Ting; Liu, Jinjin; Peng, Zheng; Xu, Shasha; Lei, Jieqiong; Deng, Hongbing; Li, Bin

    2013-01-30

    Lysozyme (Ly) and sodium carboxymethyl cellulose (CMC) were used to fabricate nanogels by a convenient method without using any chemical treatment except simple heating to achieve the denaturation temperature of Ly. The prepared nanogels were characterized by dynamic laser scattering (DLS), rheological analysis, transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The nanogels are of spherical shape with average hydrodynamic diameter of 241 nm and the swelling ratio of nanogels is about 5. Then 5-fluorouracil was used as a model drug to investigate the entrapment efficiency and release ability in nanogels. It turned out to be that the release in simulated gastric fluid (SGF) was more slowly compared with that in simulated intestinal fluid (SIF), which could protect the 5-Fu in stomach and ensure it released in intestines. PMID:23089579

  15. Analytical and numerical study of diffusion-controlled drug release from composite spherical matrices.

    PubMed

    Hadjitheodorou, Amalia; Kalosakas, George

    2014-09-01

    We investigate, both analytically and numerically, diffusion-controlled drug release from composite spherical formulations consisting of an inner core and an outer shell of different drug diffusion coefficients. Theoretically derived analytical results are based on the exact solution of Fick's second law of diffusion for a composite sphere, while numerical data are obtained using Monte Carlo simulations. In both cases, and for the range of matrix parameter values considered in this work, fractional drug release profiles are described accurately by a stretched exponential function. The release kinetics obtained is quantified through a detailed investigation of the dependence of the two stretched exponential release parameters on the device characteristics, namely the geometrical radii of the inner core and outer shell and the corresponding drug diffusion coefficients. Similar behaviors are revealed by both the theoretical results and the numerical simulations, and approximate analytical expressions are presented for the dependencies. PMID:25063169

  16. Controlled release of manganese into water from coated experimental fertilizers: laboratory characterization.

    PubMed

    Novillo, J; Rico, M I; Alvarez, J M

    2001-03-01

    The release of manganese into water from controlled-release formulations containing manganese EDTA or manganese lignosulfonate was studied. These fertilizers were obtained in the laboratory by adhering the source of manganese over urea pellets and by adding a coating. The materials used as adhesives and coatings were mixtures of rosins plus tricalcium phosphate. With regard to the chemical composition, these formulations conformed to national and international standards for commercial fertilizers. The rate of release of manganese was a function of both the source of manganese used and the coating thickness. Under the same conditions the release of manganese was greater for formulations with manganese EDTA than with manganese lignosulfonate. To predict the kinetic behaviors of the two series of formulations, mathematical equations were established. The manganese source plus rosin coatings improved the handling and storage characteristics of the commercial urea pellets. The study of the rosin coatings using scanning electron microscopy showed that they were compact and homogeneous. PMID:11312854

  17. Clinical importance of achieving biochemical control with medical therapy in adult patients with acromegaly

    PubMed Central

    Christofides, Elena A

    2016-01-01

    In acromegaly, achieving biochemical control (growth hormone [GH] level <1.0 ng/mL and age- and sex-normalized levels of insulin-like growth factor 1 [IGF-1]) through timely diagnosis and appropriate treatment provides an opportunity to improve patient outcomes. Diagnosis of acromegaly is challenging because it is rooted in observing subtle clinical manifestations, and it is typical for acromegaly to evolve for up to 10 years before it is recognized. This results in chronic exposure to elevated levels of GH and IGF-1 and delay in patients receiving appropriate treatment, which consequently increases mortality risk. In this review, the clinical impact of elevated GH and IGF-1 levels, the effectiveness of current therapies, and the potential role of novel treatments for acromegaly will be discussed. Clinical burden of acromegaly and benefits associated with management of GH and IGF-1 levels will be reviewed. Major treatment paradigms in acromegaly include surgery, medical therapy, and radiotherapy. With medical therapies, such as somatostatin analogs, dopamine agonists, and GH receptor antagonists, a substantial proportion of patients achieve reduced GH and normalized IGF-1 levels. In addition, signs and symptoms, quality of life, and comorbidities have also been reported to improve to varying degrees in patients who achieve biochemical control. Currently, there are several innovative therapies in development to improve patient outcomes, patient use, and access. Timely biochemical control of acromegaly ensures that the patient can ultimately improve morbidity and mortality from this disease and its extensive consequences. PMID:27471378

  18. Use a linear model to achieve stable composition control in a naphtha splitter

    SciTech Connect

    Karpe, P.

    1997-01-01

    The following two points using dual composition control in a naphtha splitter are emphasized: while literature provides general guidelines for design of control systems for distillation columns, each column is unique in terms of dynamic and steady state behavior. Multivariable control analytical tools, such as RGA and SVD, coupled with rigorous steady state simulations, can be effectively employed to achieve stable control in columns beset with severe loop interactions, and often in the absence of on-line analyzers, linear models representing the first order approximations of distillation columns can yield significant benefits. Such models are simple to understand, readily acceptable to operators, do not require special expertise to maintain, and therefore, offer high degree of reliability.

  19. Controlled release of cytokines using silk-biomaterials for macrophage polarization.

    PubMed

    Reeves, Andrew R D; Spiller, Kara L; Freytes, Donald O; Vunjak-Novakovic, Gordana; Kaplan, David L

    2015-12-01

    Polarization of macrophages into an inflammatory (M1) or anti-inflammatory (M2) phenotype is important for clearing pathogens and wound repair, however chronic activation of either type of macrophage has been implicated in several diseases. Methods to locally control the polarization of macrophages is of great interest for biomedical implants and tissue engineering. To that end, silk protein was used to form biopolymer films that release either IFN-γ or IL-4 to control the polarization of macrophages. Modulation of the solubility of the silk films through regulation of β-sheet (crystalline) content enabled a short-term release (4-8 h) of either cytokine, with smaller amounts released out to 24 h. Altering the solubility of the films was accomplished by varying the time that the films were exposed to water vapor. The released IFN-γ or IL-4 induced polarization of THP-1 derived macrophages into the M1 or M2 phenotypes, respectively. The silk biomaterials were able to release enough IFN-γ or IL-4 to repolarize the macrophage from M1 to M2 and vice versa, demonstrating the well-established plasticity of macrophages. High β-sheet content films that are not soluble and do not release the trapped cytokines were also able to polarize macrophages that adhered to the surface through degradation of the silk protein. Chemically conjugating IFN-γ to silk films through disulfide bonds allowed for longer-term release to 10 days. The release of covalently attached IFN-γ from the films was also able to polarize M1 macrophages in vitro. Thus, the strategy described here offers new approaches to utilizing biomaterials for directing the polarization of macrophages. PMID:26421484

  20. Formulation and evaluation of controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum

    PubMed Central

    Arora, Gurpreet; Malik, Karan; Singh, Inderbir; Arora, Sandeep; Rana, Vikas

    2011-01-01

    The aim of study was to prepare controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum as natural polymer. Tablets were formulated by direct compression technology employing the natural polymer in different concentrations (5, 10, 15 and 20% w/w). The prepared batches were evaluated for drug assay, diameter, thickness, hardness and tensile strength, swelling index, mucoadhesive strength (using texture analyzer) and subjected to in vitro drug release studies. Real-time stability studies were also conducted on prepared batches. In vitro drug release data were fitted in various release kinetic models for studying the mechanism of drug release. Tensile strength was found to increase from 0.808 ± 0.098 to 1.527 ± 0.10 mN/cm2 and mucoadhesive strength increased from 13.673 ± 1.542 to 40.378 ± 2.345 N, with an increase in the polymer concentration from 5 to 20% (A1 to A4). Swelling index was reported to increase with both increase in the concentration of gum and the time duration. The in vitro drug release decreased from 97.76 to 83.4% (A1 to A4) with the increase in polymer concentration. The drug release from the matrix tablets was found to follow zero-order and Higuchi models, indicating the matrix-forming potential of natural polymer. The value of n was found to be between 0.5221 and 0.8992, indicating the involvement of more than one drug release mechanism from the formulation and possibly the combination of both diffusion and erosion. These research findings clearly indicate the potential of S. plebeian gum to be used as binder, release retardant and mucoadhesive natural material in tablet formulations. PMID:22171313

  1. In vivo evaluation of two novel controlled-release nitrendipine formulations.

    PubMed

    Yang, Mingshi; Cui, Fude; You, Bengang; Yang, Minghua; Tao, Anjin; Cun, Dongmei; Kawashima, Yoshiaki

    2005-08-01

    The objective of this work is to assess two novel controlled-release nitrendipine formulations, i.e., sustained-release nitrendipine microspheres having solid dispersion structure and a novel pH-dependent gradient-release delivery system for nitrendipine in healthy male volunteers, which were prepared by current authors. Domestic commercial nitrendipine tablets and Baypress nitrendipine tablets were employed as reference formulations. In a randomized, single-dose, fasting-state, crossover study design with a 1-week washout period, each subject received a 40-mg nitrendipine formulation. Plasma samples were collected over a 25-hour period after oral administration and were analyzed by a validated method using high performance liquid chromatography with ultraviolet detection. Pharmacokinetic parameters were determined using a noncompartmental analysis. The results provided evidence that the time to maximum plasma concentration of two novel controlled-release nitrendipine formulations were statistically significant prolonged in comparison with that of Baypress nitrendipine tablets. The relative bioavailabilities of test formulations were intensively improved compared with the domestic nitrendipine tablets, while the ratio is in a range of 80-120% in comparison with Baypress nitrendipine tablets. It is concluded that the two types of controlled-release systems are feasible for improving the dissolution rate of nitrendipine and obtaining a long-acting in vivo as well. PMID:16207605

  2. Evaluation of microwave assisted grafted sago starch as controlled release polymeric carrier.

    PubMed

    Singh, Akhilesh Vikram; Nath, Lila Kanta

    2013-09-01

    In the present investigation an attempt has been made to develop a new co-polymeric material for controlled release tablet formulations. The acrylamide grafting was successfully performed on the backbone of sago starch. The modified starch was tested for acute toxicity and drug-excipient compatibility study. The grafted material was used in making of controlled release tablets of lamivudine. The formulations were evaluated for physical characteristics such as hardness, friability, %drug content and weight variations. The in vitro release study showed that the optimized formulation exhibited highest correlation (R) value in case of Higuchi model and the release mechanism of the optimized formulation predominantly exhibited combination of diffusion and erosion process. There was a significant difference in the pharmacokinetic parameters (T(max), C(max), AUC, V(d), T(1/2) and MDT) of the optimized formulation as compared to the marketed conventional tablet Lamivir(®) was observed. The pharmacokinetics parameters were showed controlled pattern and better bioavailability. The optimized formulation exhibited good stability and release profile at the accelerated stability conditions. PMID:23707750

  3. Glucose-Responsive Micelles for Controlled Insulin Release Based on Transformation from Amphiphilic to Double Hydrophilic.

    PubMed

    Li, Xiuhua; Shang, Hui; Wu, Wei; Li, Shuai; Lin, Zaifu; Duan, Jiawei; Xu, Lisa; Li, Jianshu

    2016-06-01

    Recently, stimuli-responsive carriers have been paid much attention to control cargo release due to their obvious advantages such as targeted delivery, reduced systematic cytotoxicity and enhanced therapeutic efficiency. In this study, a well-defined block copolymer synthesized via ATRP, i.e., poly(ethylene glycol)-b-poly(2-diisopropylaminoethyl methacrylate) (PEG-b-PDPA), has been used to investigate the insulin release behavior in response to glucose changes for potential diabetes mellitus (DM) therapy. Based on the enzymatic catalytic reaction of glucose and glucose oxidase (GOD), the acidic product (gluconic acid) can reduce the micro-environmental pH value. Thereby, the hydrophobic PDPA block with pH sensitivity can rapidly be protonated in response to the decrease of pH value. Due to the partial protonated PDPA block undergoing a variation from hydrophobic to hydrophilic, the self-assembled nanomicelle can gradually release loaded insulin in a regulated model. According to the characterizations of size, morphology, drug loading efficiency, controlled insulin release behavior, glucose sensitivity and cytotoxicity, we conclude that this delicately designed glucose-responsive nanomicelle would be an efficient self-regulated carrier for controlled insulin release for potential DM therapy. PMID:27427584

  4. Spatial Control of Gene Expression within a Scaffold by Localized Inducer Release

    PubMed Central

    Baraniak, Priya R.; Nelson, Devin M.; Leeson, Cory E.; Katakam, Anand K.; Friz, Jennifer L.; Cress, Dean E.; Hong, Yi; Guan, Jianjun; Wagner, William R.

    2011-01-01

    Gene expression can be controlled in genetically modified cells by employing an inducer/promoter system where presence of the inducer molecule regulates the timing and level of gene expression. By applying the principles of controlled release, it should be possible to control gene expression on a biomaterial surface by the presence or absence of inducer release from the underlying material matrix, thus avoiding alternative techniques that rely upon uptake of relatively labile DNA from material surfaces. To evaluate this concept, a modified ecdysone-responsive gene expression system was transfected into B16 murine cells and the ability of an inducer ligand, which was released from elastomeric poly(ester urethane) urea (PEUU), to initiate gene expression was studied. The synthetic inducer ligand was first loaded into PEUU to demonstrate extended release of the bioactive molecule at various loading densities over a one year period in vitro. Patterning films of PEUU variably-loaded with inducer resulted in spatially controlled cell expression of the gene product (green fluorescent protein, GFP). In porous scaffolds made from PEUU by salt leaching, where the central region was exclusively loaded with inducer, cells expressed GFP predominately in the loaded central regions whereas expression was minimal in outer regions where ligand was omitted. This scaffold system may ultimately provide a means to precisely control progenitor cell commitment in a spatially-defined manner in vivo for soft tissue repair and regeneration. PMID:21269687

  5. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    SciTech Connect

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  6. Synthesis, characterization, and controllable drug release of pH-sensitive hybrid magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhou, Lilin; Yuan, Jinying; Yuan, Weizhong; Sui, Xiaofeng; Wu, Sizhu; Li, Zhaolong; Shen, Dezhong

    2009-09-01

    The synthesis of magnetite nanoparticles coated with pH-sensitive poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) via atom transfer radical polymerization (ATRP) for use as novel potential carriers for targeted drug delivery and controllable release is reported. The organic/inorganic hybrid nanoparticles were obtained with a narrow molecular weight distribution. The pH-sensitivity of the nanoparticles was investigated by the measurement of the pH dependence of hydrodynamic radius and the superparamagnetism was illustrated by vibrating sample magnetometer (VSM). The behavior of model drug phenolphthalein released from the nanoparticles indicated that the rate of drug release could be effectively controlled by altering the pH values of the environment.

  7. Characterization of α-taxilin as a novel factor controlling the release of hepatitis C virus.

    PubMed

    Elgner, Fabian; Donnerhak, Christian; Ren, Huimei; Medvedev, Regina; Schreiber, André; Weber, Lorenz; Heilmann, Markus; Ploen, Daniela; Himmelsbach, Kiyoshi; Finkernagel, Malin; Klingel, Karin; Hildt, Eberhard

    2016-01-15

    Although it is well established that the release of HCV (hepatitis C virus) occurs through the secretory pathway, many aspects concerning the control of this process are not yet fully understood. α-Taxilin was identified as a novel binding partner of syntaxin-4 and of other members of the syntaxin family, which are part of SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) complexes and so are involved in intracellular vesicle traffic. Since α-taxilin prevents t-SNARE (target SNARE) formation by binding exclusively to free syntaxin-4, it exerts an inhibitory effect on the vesicular transport. HCV-replicating Huh7.5 cells and HCV-infected primary human hepatocytes and liver samples of patients suffering from chronic HCV contain significantly less α-taxilin compared with the controls. HCV impairs the expression of α-taxilin via NS5A-dependent interruption of the Raf/MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase] signal transduction cascade. Moreover, the half-life of α-taxilin is significantly reduced in HCV-replicating cells. Whereas modulation of α-taxilin expression does not significantly affect genome replication, the overexpression of α-taxilin prevents the release of HCV. In contrast with this, silencing of α-taxilin expression leads to increased release of infectious viral particles. This is due to the negative effect of α-taxilin on t-SNARE formation that leads to impaired vesicular trafficking. Accordingly, overexpression of the t-SNARE component syntaxin-4 increases release of HCV, whereas silencing leads to an impaired release. These data identify α-taxilin as a novel factor that controls the release of HCV and reveal the mechanism by which HCV controls the activity of α-taxilin. PMID:26527738

  8. Controlled release fungicide, soil amendments and biofumigation effects on cotton root rot suppression

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cotton root rot pathogen (Phymatotrichopsis ominora) causes major losses in cotton produced in the Southwest. Granular controlled release formulations (CRF) of the fungicide, Propiconazole, developed to be soil applied at planting were studied at 1.0 and 3.0 lb a.i./ac. applications and with tw...

  9. Biological control of tropical soda apple (Solanaceae) in Florida: Post-release evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The leaf feeding beetle Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) was released as a biological control agent against tropical soda apple (TSA) (Solanum viarum Dunal (Solanaceae)) in Sumter County, FL in 2006. Evaluation of beetle feeding damage to TSA plants and changes in the beetle po...

  10. Oil and drug control the release rate from lyotropic liquid crystals.

    PubMed

    Martiel, Isabelle; Baumann, Nicole; Vallooran, Jijo J; Bergfreund, Jotam; Sagalowicz, Laurent; Mezzenga, Raffaele

    2015-04-28

    The control of the diffusion coefficient by the dimensionality d of the structure appears as a most promising lever to efficiently tune the release rate from lyotropic liquid crystalline (LLC) phases and dispersed particles towards sustained, controlled and targeted release. By using phosphatidylcholine (PC)- and monolinoleine (MLO)-based mesophases with various apolar structural modifiers and water-soluble drugs, we present a comprehensive study of the dimensional structural control of hydrophilic drug release, including 3-d bicontinuous cubic, 2-d lamellar, 1-d hexagonal and 0-d micellar cubic phases in excess water. We investigate how the surfactant, the oil properties and the drug hydrophilicity mitigate or even cancel the effect of structure variation on the drug release rate. Unexpectedly, the observed behavior cannot be fully explained by the thermodynamic partition of the drug into the lipid matrix, which points out to previously overlooked kinetic effects. We therefore interpret our results by discussing the mechanism of structural control of the diffusion rate in terms of drug permeation through the lipid membrane, which includes exchange kinetics. A wide range of implications follow regarding formulation and future developments, both for dispersed LLC delivery systems and topical applications in bulk phase. PMID:25744826

  11. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microencapsulation and controlled release of Pantoea agglomerans strain E325 (E325), which is an antagonist to bacterial pathogen (Erwinia amylovora) of fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 µm in diamet...

  12. The effect of controlled-release ClO2 on the preservation of grapefruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of controlled-release ClO2 gas on the safety and quality of grapefruit was studied. Three different tests were run: 1) isolated peel tissue with microorganism inoculation in a chamber system; 2) individual fruit with microorganism inoculation in a chamber; and 3) boxed fruit under commerc...

  13. Localized controlled release of stratifin reduces implantation-induced dermal fibrosis.

    PubMed

    Rahmani-Neishaboor, Elham; Hartwell, Ryan; Jalili, Reza; Jackson, John; Brown, Erin; Ghahary, Aziz

    2012-10-01

    Localized controlled release of anti-fibrogenic factors can potentially prevent tissue fibrosis surrounding biomedical prostheses, such as vascular stents and breast implants. We have previously demonstrated that therapeutic intervention with topically applied stratifin in a rabbit ear fibrotic model not only prevents dermal fibrosis but also promotes more normal tissue repair by regulating extracellular matrix deposition. In this work, the anti-fibrogenic effect of a controlled release form of stratifin was investigated in the prevention of fibrosis induced by dermal poly(lactic-co-glycolic acid) (PLGA) microsphere/poly(vinyl alcohol) (PVA) hydrogel implants. Pharmacodynamic effects were evaluated by histopathological examination of subcutaneous tissue surrounding implanted composites. Controlled release of stratifin from PLGA microsphere/PVA hydrogel implants significantly moderated dermal fibrosis and inflammation by reducing collagen deposition (30%), total tissue cellularity (48%) and infiltrated CD3(+) immune cells (81%) in the surrounding tissue compared with the stratifin-free implants. The controlled release of stratifin from implants markedly increased the level of matrix metalloproteinase-1 expression in the surrounding tissue, which resulted in less collagen deposition. These stratifin-eluting PLGA/PVA composites show promise as coatings to decrease the typical fibrosis exhibited around implanted biomedical prostheses, such as breast implants and vascular stents. PMID:22743110

  14. Design Project on Controlled-Release Drug Delivery Devices: Implementation, Management, and Learning Experiences

    ERIC Educational Resources Information Center

    Xu, Qingxing; Liang, Youyun; Tong, Yen Wah; Wang, Chi-Hwa

    2010-01-01

    A design project that focuses on the subject of controlled-release drug delivery devices is presented for use in an undergraduate course on mass transfer. The purpose of the project is to introduce students to the various technologies used in the fabrication of drug delivery systems and provide a practical design exercise for understanding the…

  15. EVALUATION OF BIOREMEDIATION STRATEGIES OF A CONTROLLED OIL RELEASE IN A WETLAND

    EPA Science Inventory

    A controlled petroleum release was conducted to evaluate bioremediation in a wetland near Houston, Texas. The 140-day study was conducted using a randomized, complete block design to test three treatments with six replicates per treatment. The three treatment strategies were in...

  16. [Effects of applying controlled-release compound fertilizer on Platycodon grandiflorum growth].

    PubMed

    Zhu, Li-xiang; Wang, Jian-hua

    2010-09-01

    A pot experiment was conducted in 2008 to study the effects of applying controlled-release compound fertilizer (N:P2O5:K2O = 14:14:14) on the growth of Platycodon grandiflorum in the medicinal herbal farm of Shandong Agricultural University. Comparing with the application of common compound fertilizer (N:P2O5: K2O=15: 15: 15), applying equivalent amount of the controlled-release fertilizer increased the leaf chlorophyll content, root volume, root activity, and root diameter of P. grandiflorum at the late growth stage, but decreased the root length. When the N application rate was 0.24 and 0.32 g x kg(-1) soil, applying the controlled-release compound fertilizer increased the root yield by 26.78% and 22.50%, and the root soluble sugar, protein, and total saponin contents by 9.77% and 6.99%, 11.38% and 2.20%, and 8.85% and 5.47%, respectively, compared with applying the common compound fertilizer. More nitrogen application made the root soluble sugar content decreased but the total saponin content increased. Under our experimental condition, applying the controlled-release compound fertilizer with an application rate of 0.24 g N x kg(-1) soil could obtain the best effect for P. grandiflorum. PMID:21265152

  17. Longevity of controlled release fertilizer influences the growth of bedding Impatiens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlled-release fertilizers (CRF) have not been extensively used in floriculture production, perhaps due to lack of grower experience and research-based information with their use in herbaceous plant production. Any information about the correct use of CRF should increase growers’ confidence in ...

  18. Controlled Release Fertilizers: An Environmentally Sound and Efficient Method for Greenhouse Crop Fertilization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lake Erie is the most polluted of all the Great Lakes. In fact, the Maumee River Watershed alone contributes most of Lake Erie’s phosphorus and sediment load but only 3% of its water, due to the large concentration of agriculture in this portion of the state. The use of controlled release fertilize...

  19. Effects of Controlled Release Fertilizer on the Post-Production Performance of Impatiens Wallerana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlled release fertilizers (CRF) in production systems have been known to reduce environmental contamination. However, there is a lot to be explored as per its use in bedding plant production. Bedding plant growers have not adapted CRF use because there is little information about its use and ...

  20. Development and evaluation of diltiazem hydrochloride controlled-release pellets by fluid bed coating process

    PubMed Central

    Prasad, Mikkilineni Bhanu; Vidyadhara, Suryadevara; Sasidhar, Reddyvalam Lankapalli C.; Balakrishna, Talamanchi; Trilochani, Pavuluri

    2013-01-01

    The aim of the present study was to develop controlled-release pellets of diltiazem HCl with ethyl cellulose and hydroxylpropyl methylcellulose phthalate as the release rate retarding polymers by fluid bed coating technique. The prepared pellets were evaluated for drug content, particle size, subjected to Scanning Electron Microscopy (SEM) and Differential Scanning Calori metry (DSC), and evaluated for in vitro release. Stability studies were carried out on the optimized formulations for a period of 3 months. The drug content was in the range of 97%-101%. The mean particle size of the drug-loaded pellets was in the range 700-785 μm. The drug release rate decreased as the concentration of ethyl cellulose increased in the pellet formulations. Among the prepared formulations, FDL10 and FDL11 showed 80% drug release in 16 h, matching with USP dissolution test 6 for diltiazem HCl extended-release capsules. SEM photographs confirmed that the prepared formulations were spherical in nature with a smooth surface. The compatibility between drug and polymers in the drug-loaded pellets was confirmed by DSC studies. Stability studies indicated that the pellets were stable. PMID:23833750

  1. Synthesis, characterization, and controlled release antibacterial behavior of antibiotic intercalated Mg–Al layered double hydroxides

    SciTech Connect

    Wang, Yi; Zhang, Dun

    2012-11-15

    Graphical abstract: The antibiotic anion released from Mg–Al LDHs provides a controlled release antibacterial activity against the growth of Micrococcus lysodeikticus in 3.5% NaCl solution. Highlights: ► Antibiotic anion intercalated LDHs were synthesized and characterized. ► The ion-exchange one is responsible for the release process. ► The diffusion through particle is the release rate limiting step. ► LDHs loaded with antibiotic anion have high antibacterial capabilities. -- Abstract: Antibiotic–inorganic clay composites including four antibiotic anions, namely, benzoate (BZ), succinate (SU), benzylpenicillin (BP), and ticarcillin (TC) anions, intercalated Mg–Al layered double hydroxides (LDHs) were synthesized via ion-exchange. Powder X-ray diffraction and Fourier transform infrared spectrum analyses showed the successful intercalation of antibiotic anion into the LDH interlayer. BZ and BP anions were accommodated in the interlayer region as a bilayer, whereas SU and TC anions were intercalated in a monolayer arrangement. Kinetic simulation of the release data indicated that ion-exchange was responsible for the release process, and the diffusion through the particles was the rate-limiting step. The antibacterial capabilities of LDHs loaded with antibiotic anion toward Micrococcus lysodeikticus growth were analyzed using a turbidimetric method. Significant high inhibition rate was observed when LDH nanohybrid was introduced in 3.5% NaCl solution. Therefore, this hybrid material may be applied as nanocontainer in active antifouling coating for marine equipment.

  2. Concepts for Life Cycle Cost Control Required to Achieve Space Transportation Affordability and Sustainability

    NASA Technical Reports Server (NTRS)

    Rhodes, Russel E.; Zapata, Edgar; Levack, Daniel J. H.; Robinson, John W.; Donahue, Benjamin B.

    2009-01-01

    Cost control must be implemented through the establishment of requirements and controlled continually by managing to these requirements. Cost control of the non-recurring side of life cycle cost has traditionally been implemented in both commercial and government programs. The government uses the budget process to implement this control. The commercial approach is to use a similar process of allocating the non-recurring cost to major elements of the program. This type of control generally manages through a work breakdown structure (WBS) by defining the major elements of the program. If the cost control is to be applied across the entire program life cycle cost (LCC), the approach must be addressed very differently. A functional breakdown structure (FBS) is defined and recommended. Use of a FBS provides the visibifity to allow the choice of an integrated solution reducing the cost of providing many different elements of like function. The different functional solutions that drive the hardware logistics, quantity of documentation, operational labor, reliability and maintainability balance, and total integration of the entire system from DDT&E through the life of the program must be fully defined, compared, and final decisions made among these competing solutions. The major drivers of recurring cost have been identified and are presented and discussed. The LCC requirements must be established and flowed down to provide control of LCC. This LCC control will require a structured rigid process similar to the one traditionally used to control weight/performance for space transportation systems throughout the entire program. It has been demonstrated over the last 30 years that without a firm requirement and methodically structured cost control, it is unlikely that affordable and sustainable space transportation system LCC will be achieved.

  3. Study of a Simulation Tool to Determine Achievable Control Dynamics and Control Power Requirements with Perfect Tracking

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.

    1998-01-01

    This paper contains a study of two methods for use in a generic nonlinear simulation tool that could be used to determine achievable control dynamics and control power requirements while performing perfect tracking maneuvers over the entire flight envelope. The two methods are NDI (nonlinear dynamic inversion) and the SOFFT(Stochastic Optimal Feedforward and Feedback Technology) feedforward control structure. Equivalent discrete and continuous SOFFT feedforward controllers have been developed. These equivalent forms clearly show that the closed-loop plant model loop is a plant inversion and is the same as the NDI formulation. The main difference is that the NDI formulation has a closed-loop controller structure whereas SOFFT uses an open-loop command model. Continuous, discrete, and hybrid controller structures have been developed and integrated into the formulation. Linear simulation results show that seven different configurations all give essentially the same response, with the NDI hybrid being slightly different. The SOFFT controller gave better tracking performance compared to the NDI controller when a nonlinear saturation element was added. Future plans include evaluation using a nonlinear simulation.

  4. Investigation of cenderitide controlled release platforms for potential local treatment of cardiovascular pathology.

    PubMed

    Ng, Xu Wen; Huang, Yingying; Liu, Kerh Lin; Boey, Freddy Y C; Venkatraman, Subbu S

    2014-05-01

    In this work, we focused on the development and investigation of controlled release matrices for a novel cardiotherapeutic peptide, cenderitide (CD-NP) that has shown to be useful for control of ventricular remodeling. To circumvent the hydrophilicity disparity between CD-NP and hydrophobic polymer matrix, a cosolvent system (water/dichloromethane) was selected for investigation. The effect of emulsification conditions, addition of poly(ethylene glycol) (PEG) and its copolymer on the release mechanism and profile were investigated. To verify the retention of bioactivity of entrapped CD-NP in different formulations, the generation of 3',5' cyclic guanosine monophospate (cGMP) and the inhibition of human cardiac fibroblast (HCF) were evaluated. The results showed that neat poly(ε-caprolactone) matrices carried out via two distinct emulsification conditions had either an unacceptably high burst or incomplete release of CD-NP; and the addition of PEG and its copolymer obtained intermediate profiles. Our confocal laser scanning microscopy and surface morphological investigations showed that the copolymer excipient was superior in playing stabilizer role by colocalizing and redistributing peptide throughout the matrix, making the release less sensitive to emulsification conditions. Furthermore, the released CD-NP is able to generate the cGMP and inhibit the HCF proliferation. Our investigations showed that CD-NP-loaded platforms can be a feasible option to provide sustained antifibrotic moderation of fibrotic scar formation and be potentially used to alleviate the adverse effects of cardiac remodeling. PMID:24590596

  5. Formulation and bioavailability of controlled release salbutamol sulphate tablets using natural additives.

    PubMed

    Nouh, A T; Abd El-Gawad, A H; Guda, T K

    2010-04-01

    Salbutamol sulphate granules and physical mixtures were prepared using mastic with various natural additives. The prepared granules and physical mixtures were examined using IR and DSC. The obtained results indicate that there is no interaction between salbutamol sulphate and the formulation ingredients used. The physical properties and release behavior of the formulated tablets prepared from granules and physical mixtures were evaluated and showed good physical properties. The rate of drug release from tablets prepared from granules was found to be lower than that prepared from physical mixtures at fixed mastic concentration and the same additive. The rate of drug release decreased with increased mastic concentration in formulated tablets. Pectin and sodium alginate allowed the best controlled release rate of the drug. On the basis of the results obtained from the controlled release studies, selected sulbutamol formulations were subjected to an in vivo comparison with commercial sulbutamol tablets. The pharmacokinetic parameters AUC(0-24), C(max), and T(max) of sulbutamol from the selected formulation were determined after administration of a single oral dose of 8 mg and compared statistically using an ANOVA test. There was no significant difference in the AUC(0-24). On the other hand, there was a significant difference in the C(max) and T(max) between the commercial and the formulated tablets. These results demonstrate that the formulated tablets extended the time of the drug effect. PMID:22491165

  6. Nano-Storage Wires for the Controlled Release of Biochemical Materials

    NASA Astrophysics Data System (ADS)

    Yoo, Haneul; Lee, Dongjun; Kim, Eunji; Kim, Daesan; Park, Juhun; Hong, Seunghun

    2015-03-01

    We herein report ``nano-storage wires'' (NSWs) that can store chemical species and release them at a desired moment by electrical stimulations. Here, we utilized the electrodeposition process through an anodized aluminium oxide template to fabricate multi-segmented nanowires which consisted of a polypyrrole (PPy) segment containing adenosine triphosphate (ATP) molecules, a ferromagnetic nickel segment, and a conductive gold segment. We could drive and deposit the NSWs onto desired positions on electrode surfaces via external magnetic fields. When the external electric potential was applied from the electrodes, the NSWs released ATPs from the PPy segments, and the released ATPs could change the activities of motor proteins near the NSWs. Furthermore, through direct writing or magnetic manipulation strategies, we could print NSWs onto various substrates such as flexible or three-dimensional structured substrates to build versatile chemical storage devices. Since our strategy enables the controllable storage and release of chemicals, our development should open up various applications such as drug delivery systems, biosensors and biochips for the controlled release of chemicals to biosystems.

  7. Multi-Drug-Loaded Microcapsules with Controlled Release for Management of Parkinson's Disease.

    PubMed

    Baek, Jong-Suep; Choo, Chee Chong; Qian, Cheng; Tan, Nguan Soon; Shen, Zexiang; Loo, Say Chye Joachim

    2016-07-01

    Parkinson's disease (PD) is a progressive disease of the nervous system, and is currently managed through commercial tablets that do not sufficiently enable controlled, sustained release capabilities. It is hypothesized that a drug delivery system that provides controlled and sustained release of PD drugs would afford better management of PD. Hollow microcapsules composed of poly-l-lactide (PLLA) and poly (caprolactone) (PCL) are prepared through a modified double-emulsion technique. They are loaded with three PD drugs, i.e., levodopa (LD), carbidopa (CD), and entacapone (ENT), at a ratio of 4:1:8, similar to commercial PD tablets. LD and CD are localized in both the hollow cavity and PLLA/PCL shell, while ENT is localized in the PLLA/PCL shell. Release kinetics of hydrophobic ENT is observed to be relatively slow as compared to the other hydrophilic drugs. It is further hypothesized that encapsulating ENT into PCL as a surface coating onto these microcapsules can aid in accelerating its release. Now, these spray-coated hollow microcapsules exhibit similar release kinetics, according to Higuchi's rate, for all three drugs. The results suggest that multiple drug encapsulation of LD, CD, and ENT in gastric floating microcapsules could be further developed for in vivo evaluation for the management of PD. PMID:27253884

  8. Okra (Hibiscus esculentus) gum-alginate blend mucoadhesive beads for controlled glibenclamide release.

    PubMed

    Sinha, Priyanka; Ubaidulla, U; Nayak, Amit Kumar

    2015-01-01

    The utility of isolated okra (Hibiscus esculentus) gum (OG) was evaluated as a potential sustained drug release polymer-blends with sodium alginate in the development of controlled glibenclamide release ionically-gelled beads for oral use. OG was isolated from okra fruits and its solubility, pH, viscosity and moisture content were studied. Glibenclamide-loaded OG-alginate blend beads were prepared using CaCl2 as cross-linking agent through ionic-gelation technique. These ionically gelled beads showed drug entrapment efficiency of 64.19 ± 2.02 to 91.86 ± 3.24%. The bead sizes were within 1.12 ± 0.11 to 1.28 ± 0.15 mm. These glibenclamide-loaded OG-alginate blend beads exhibited sustained in vitro drug release over a prolonged period of 8 h. The in vitro drug release from these OG-alginate beads were followed controlled-release (zero-order) pattern with super case-II transport mechanism. The beads were also characterized by SEM and FTIR. The swelling and degradation of these beads was influenced by the pH of the test medium. These beads also exhibited good mucoadhesivity with goat intestinal mucosa. PMID:25312603

  9. Multilayer Films Assembled from Naturally-Derived Materials for Controlled Protein Release

    PubMed Central

    Hsu, Bryan B.; Hagerman, Samantha R; Jamieson, Kelsey; Veselinovic, Jovana; O’Neill, Nicholas; Holler, Eggehard; Ljubimova, Julia Y.; Hammond, Paula T.

    2014-01-01

    Herein we designed and characterized films composed of naturally derived materials for controlled release of proteins. Traditional drug delivery strategies rely on synthetic or semi-synthetic materials, or utilize potentially denaturing assembly conditions that are not optimal for sensitive biologics. Layer-by-Layer (LbL) assembly of films uses benign conditions and can generate films with various release mechanisms including hydrolysis-facilitated degradation. These use components such as synthetic polycations that degrade into non-natural products. Herein we report the use of a naturally-derived, biocompatible and degradable polyanion, poly(β-l-malic acid), alone and in combination with chitosan in an LbL film, whose degradation products of malic acid and chitosan are both generally recognized as safe (GRAS) by the FDA. We have found that films based on this polyanion have shown sustained release of a model protein, lysozyme that can be timed from tens of minutes to multiple days through different film architectures. We also report the incorporation and release of a clinically used biologic, basic fibroblast growth factor (bFGF), which demonstrates the use of this strategy as a platform for controlled release of various biologics. PMID:24825478

  10. Development of floating chitosan-xanthan beads for oral controlled release of glipizide

    PubMed Central

    Kulkarni, Nilesh; Wakte, Pravin; Naik, Jitendra

    2015-01-01

    Introduction: The aim of the present work was to develop controlled release, floating and mucoadhesive beads of glipizide by using the polyionic complexation technique. Plasma half-life of glipizide being 2–4 h was selected for development of controlled release dosage form. Methods: Formulation batches were designed by employing chitosan as cationic and xanthan gum as anionic polymers. In vitro drug release was evaluated for the period of 24 h in phosphate buffer pH 7.4. Results: Sustained release of drug was observed in all formulation batches with % drug release ranging from 87.50% to 100.67%, no significant effect on the drug release was observed after varying chitosan to xanthan gum ratio. Encapsulation efficiency was found to be in the range of 79.48 ± 1.10–94.48 ± 1.52. In vitro bioadhesion studies showed that beads had satisfactory bioadhesive strength ranging from 67.11% ± 1.73% to 93.12% ± 1.56%. Buoyancy studies revealed that beads possess comparable floating capacity in the gastric fluids. Swelling kinetics was carried in pH 1.2 and 7.4 buffers. Significant difference (P < 0.05) in swelling kinetics was observed. Drug to polymer interaction was analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry studies. Scanning electron microscopy studies revealed that formed beads were discrete with rough and wrinkled surfaces. Conclusions: In conclusion, beads were successfully formed by employing chitosan and xanthan gum and showed to possess sustained release effect. Beads also showed pH dependent swelling kinetics, this property can also be applied for the drugs which are susceptible to the acidic environment in the stomach, and comparable bioadhesive and floating properties were also observed. PMID:25838991

  11. Design of a timed and controlled release osmotic pump system of atenolol.

    PubMed

    Xue, Yingna; Yu, Shihui; Wang, Hanbing; Liang, Jingge; Peng, Junjie; Li, Jiang; Yang, Xinggang; Pan, Weisan

    2015-06-01

    The objective of the article was to design a novel timed and controlled release osmotic pump (TCOP) containing atenolol as an active pharmaceutical ingredient and compare with a bilayer-core osmotic pump (BCOP) of atenolol. Different from BCOP, a modulating barrier was added to delay the drug release and obtain desired lag time (Tlag). The influences of the amount of pore-forming agent and modulating barrier, coating weight gain on the lag time (Tlag) and drug release rate (Rt) of TCOP were investigated. The central composite design-response surface methodology (RSM) was applied to optimize the formulation. Rhodamine B was added to modulating barrier to determine the release process of modulating barrier. A method used to correct the release profiles with a certain lag time by ΔTlag and interpolating was applied to compare TCOP with BCOP. Tlag was directly proportional to the amount of modulating barrier and coating weight gain, but inversely related to the amount of pore forming agent, which were contrary to the effects on Rt. The optimal formulation including 60 mg PEO WSR N80, 3 g PEG 4000 and 6% coating weight gain could obtain a 3.59-h Tlag. According to the release of Rhodamine B, the modulating barrier was completely pushed out at ∼5.0 h, longer than 3.59 h, therefore, atenolol along with remaining modulating barrier was released together between 3.59 and 5.0 h. By comparing with BCOP, the release profiles subtracting the part of lag time had no significant difference, yet Rt of TCOP presented a slight decrease. PMID:24796273

  12. Dynamic Polymeric Microtubes for the Remote-Controlled Capture, Guidance, and Release of Sperm Cells.

    PubMed

    Magdanz, Veronika; Guix, Maria; Hebenstreit, Franziska; Schmidt, Oliver G

    2016-06-01

    Remote-controlled release of single sperm cells is demonstrated by the use of polymeric microtubes that unfold upon temperature increase to 38 °C. Thermoresponsive, ferromagnetic multilayers are tailored to catch sperm cells and remotely control them by external magnetic fields. These polymeric spermbots are propelled by the sperm flagella. When the temperature is increased, the tubes unfold and the cell is set free. PMID:27003908

  13. ELKS controls the pool of readily releasable vesicles at excitatory synapses through its N-terminal coiled-coil domains

    PubMed Central

    Held, Richard G; Liu, Changliang; Kaeser, Pascal S

    2016-01-01

    In a presynaptic nerve terminal, synaptic strength is determined by the pool of readily releasable vesicles (RRP) and the probability of release (P) of each RRP vesicle. These parameters are controlled at the active zone and vary across synapses, but how such synapse specific control is achieved is not understood. ELKS proteins are enriched at vertebrate active zones and enhance P at inhibitory hippocampal synapses, but ELKS functions at excitatory synapses are not known. Studying conditional knockout mice for ELKS, we find that ELKS enhances the RRP at excitatory synapses without affecting P. Surprisingly, ELKS C-terminal sequences, which interact with RIM, are dispensable for RRP enhancement. Instead, the N-terminal ELKS coiled-coil domains that bind to Liprin-α and Bassoon are necessary to control RRP. Thus, ELKS removal has differential, synapse-specific effects on RRP and P, and our findings establish important roles for ELKS N-terminal domains in synaptic vesicle priming. DOI: http://dx.doi.org/10.7554/eLife.14862.001 PMID:27253063

  14. Preparation and characterisation of controlled release co-spray dried drug-polymer microparticles for inhalation 2: evaluation of in vitro release profiling methodologies for controlled release respiratory aerosols.

    PubMed

    Salama, Rania O; Traini, Daniela; Chan, Hak-Kim; Young, Paul M

    2008-09-01

    Three in vitro methodologies were evaluated as models for the analysis of drug release from controlled release (CR) microparticulates for inhalation. USP Apparatus 2 (dissolution model), USP Apparatus 4 (flow through model) and a modified Franz cell (diffusion model), were investigated using identical sink volumes and temperatures (1000 ml and 37 degrees C). Microparticulates containing DSCG and different percentages of PVA (0%, 30%, 50%, 70% and 90%) were used as model CR formulations. Evaluation of the release profiles of DSCG from the modified PVA formulations, suggested that all data fitted a Weibull distribution model with R2 > or =0.942. Statistical analysis of the t(d) (time for 63.2% drug release) indicated that all methodologies could distinguish between microparticles that did or did not contain PVA (Students t-test, p<0.05). However, only the diffusion model could differentiate between samples containing different PVA percentages. Similar results were observed when analysing the data using similarity and difference factors. Furthermore, analysis of the release kinetic profiles for all samples suggested the data fitted the Higuchi diffusion model (R2 > or =0.862 for the diffusion methodology data set). Due to the relatively low water content in the respiratory tract and the lack of differentiation between formulations for USP Apparatus 2 and 4, it is concluded that the diffusion model is more applicable for the evaluation of CR inhalation medicines. PMID:18534832

  15. Evaluation of Plantago major L. seed mucilage as a rate controlling matrix for sustained release of propranolol hydrochloride.

    PubMed

    Saeedi, Majid; Morteza-Semnani, Katayoun; Sagheb-Doust, Mehdi

    2013-03-01

    Polysaccharide mucilage derived from the seeds of Plantago major L. (family Plantaginaceae) was investigated for use in matrix formulations containing propranolol hydrochloride. HPMC K4M and tragacanth were used as standards for comparison. The hardness, tensile strength, and friability of tablets increased as the concentration of mucilage increased, indicating good compactibility of mucilage powders. The rate of release of propranolol hydrochloride from P. major mucilage matrices was mainly controlled by the drug/mucilage ratio. Formulations containing P. major mucilage were found to exhibit a release rate comparable to HPMC containing matrices at a lower drug/polymer ratio (drug/HPMC 2:1). These results demonstrated that P. major mucilage is a better release retardant compared to tragacanth at an equivalent content. The results of kinetic analysis showed that in F3 (containing 1:2 drug/mucilage) the highest correlation coefficient was achieved with the zero order model. The swelling and erosion studies revealed that as the proportion of mucilage in tablets was increased, there was a corresponding increase in percent swelling and a decrease in percent erosion of tablets. The DSC and FT-IR studies showed that no formation of complex between the drug and mucilage or changes in crystallinity of the drug had occurred. PMID:23482316

  16. An integrative model of the cardiac ventricular myocyte incorporating local control of Ca2+ release.

    PubMed Central

    Greenstein, Joseph L; Winslow, Raimond L

    2002-01-01

    The local control theory of excitation-contraction (EC) coupling in cardiac muscle asserts that L-type Ca(2+) current tightly controls Ca(2+) release from the sarcoplasmic reticulum (SR) via local interaction of closely apposed L-type Ca(2+) channels (LCCs) and ryanodine receptors (RyRs). These local interactions give rise to smoothly graded Ca(2+)-induced Ca(2+) release (CICR), which exhibits high gain. In this study we present a biophysically detailed model of the normal canine ventricular myocyte that conforms to local control theory. The model formulation incorporates details of microscopic EC coupling properties in the form of Ca(2+) release units (CaRUs) in which individual sarcolemmal LCCs interact in a stochastic manner with nearby RyRs in localized regions where junctional SR membrane and transverse-tubular membrane are in close proximity. The CaRUs are embedded within and interact with the global systems of the myocyte describing ionic and membrane pump/exchanger currents, SR Ca(2+) uptake, and time-varying cytosolic ion concentrations to form a model of the cardiac action potential (AP). The model can reproduce both the detailed properties of EC coupling, such as variable gain and graded SR Ca(2+) release, and whole-cell phenomena, such as modulation of AP duration by SR Ca(2+) release. Simulations indicate that the local control paradigm predicts stable APs when the L-type Ca(2+) current is adjusted in accord with the balance between voltage- and Ca(2+)-dependent inactivation processes as measured experimentally, a scenario where common pool models become unstable. The local control myocyte model provides a means for studying the interrelationship between microscopic and macroscopic behaviors in a manner that would not be possible in experiments. PMID:12496068

  17. Release and distribution of Lilioceris cheni (Coleoptera: Chrysomelidae), a biological control agent of air potato (Dioscorea bulbilfera: Dioscoreaceae), in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    From 2012 to 2015, 429,668 Lilioceris cheni Gressit and Kimoto (Coleoptera: Chrysomelidae) were released in Florida for biological control of air potato [Dioscorea bulbilfera L. (Dioscoreaceae)]. The spatial distribution of releases was highly aggregated, with several areas of high density releases ...

  18. Design of magnetic molecularly imprinted polymer nanoparticles for controlled release of doxorubicin under an alternative magnetic field in athermal conditions.

    PubMed

    Griffete, N; Fresnais, J; Espinosa, A; Wilhelm, C; Bée, A; Ménager, C

    2015-12-01

    An innovative magnetic delivery nanomaterial for triggered cancer therapy showing active control over drug release by using an alternative magnetic field is proposed. In vitro and In vivo release of doxorubicin (DOX) were investigated and showed a massive DOX release under an alternative magnetic field without temperature elevation of the medium. PMID:26515533

  19. Dispersion of halloysite loaded with natural antimicrobials into pectins: Characterization and controlled release analysis.

    PubMed

    Gorrasi, Giuliana

    2015-01-01

    This paper reports the preparation and characterization of green composites based on pectins and nano-hybrids composed of halloysite nanotubes (HNTs) loaded with rosemary essential oil. Different hybrid percentages were mixed into a pectin matrix, by ball milling in the presence of water. Cast films were obtained and analyzed. Structural organization and physical properties (thermal, mechanical, barrier to water vapor) were correlated to the nano-hybrid content. A preliminary study on the kinetics of release of the rosmarinic acid, chosen as a model molecule, was also performed. This work showed the potential of these systems in the active packaging field where controlled release of active species is required. PMID:25965455

  20. Mimicking Biological Delivery Through Feedback-Controlled Drug Release Systems Based on Molecular Imprinting

    PubMed Central

    Kryscio, David R.; Peppas, Nicholas A.

    2015-01-01

    Intelligent drug delivery systems (DDS) are able to rapidly detect a biological event and respond appropriately by releasing a therapeutic agent; thus, they are advantageous over their conventional counterparts. Molecular imprinting is a promising area that generates a polymeric network which can selectively recognize a desired analyte. This field has been studied for a variety of applications over a long period of time, but only recently has it been investigated for biomedical and pharmaceutical applications. Recent work in the area of molecularly imprinted polymers in drug delivery highlights the potential of these recognitive networks as environmentally responsive DDS that can ultimately lead to feedback controlled recognitive release systems. PMID:26500352

  1. Blood, sweat, tears and success of technology transfer long-term controlled-release of herbicides

    SciTech Connect

    Van Voris, P.; Cataldo, D.A.; Burton, F.G.; Skeins, W.E.

    1988-01-01

    The problems encountered, the technical difficulties that had to be overcome, and the successful transfer of technology related to controlled-release of pesticides is reviewed. Research on control-release of pesticides to date has resulted in products designed to extend bioactivity for periods of several days, months, or at most, several years. However, research supported by the U.S. Department of Energy directed toward solving problems associated with plant-root penetration through caps and liners engineered to minimize leaching or movement of buried nuclear and chemical wastes has resulted in development of a long-term controlled-release herbicide delivery system designed to stop root growth for periods of up to 100 years. Through the unique combination of polymers with a herbicidally active dinitroaniline, a cylindrical pellet was developed that continuously releases a herbicide for a period of up to 100 years. Equilibrium concentration of the herbicide in soil adjacent to the pellet and the bioactive lifetime of the device can be adjusted by changing the size of the pellet; the type of polymer; the type, quality, and quantity of carrier; and/or the concentration and type of dinitroaniline was used.

  2. Clean Photothermal Heating and Controlled Release from Near-Infrared Dye Doped Nanoparticles without Oxygen Photosensitization.

    PubMed

    Guha, Samit; Shaw, Scott K; Spence, Graeme T; Roland, Felicia M; Smith, Bradley D

    2015-07-21

    The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of (1)O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive (1)O2, leading to bleaching of the dye and also decomposition of coencapsulated payload such as the drug doxorubicin. Croc dye was especially useful as a photothermal agent for laser-controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water-soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications. PMID:26149326

  3. Alginate/quaternized carboxymethyl chitosan/clay nanocomposite microspheres: preparation and drug-controlled release behavior.

    PubMed

    Liu, Bo; Luo, Jiwen; Wang, Xiaoying; Lu, Junxiang; Deng, Hongbing; Sun, Runcang

    2013-01-01

    Drug-delivery systems, using natural drug carriers, have become increasingly important because of their nontoxicity and biodegradability. In this study, firstly, quaternized carboxymethyl chitosan (QCMC) was intercalated into the interlayer of organic montmorillonite (OMMT) to obtain the QCMC/OMMT nanocomposites, their structure, morphology, and thermal stability were investigated. Next, crosslinked alginate/QCMC/OMMT (AQCOM) microsphere was obtained by crosslinking with CaCl2, and the drug-controlled release behavior was evaluated with bovine serum albumin (BSA) as model drug. The results suggested that, carboxyl groups in alginate and QCMC crosslinked with Ca(2+), quaternary ammonium groups in QCMC or OMMT electrostatically interacted with carboxyl groups in alginate, and there was stable three-dimensional network in AQCOM microsphere. The swelling ratio of AQCOM microspheres decreased with the increase of OMMT content, the lowest one was only about 45% compared to the microsphere without OMMT of 197%. Besides, the in vitro release results for BSA indicated that the AQCOM microsphere displayed more excellent encapsulation and controlled release capacities than the microsphere without OMMT. The in vitro active cutaneous anaphylaxis test was carried out on Guinea pigs, which revealed that AQCOM microsphere did not cause anaphylaxis. Therefore, QCMC/OMMT nanocomposites from natural materials are considerably suitable to apply as drug-controlled release carriers. PMID:23565870

  4. Chitosan-starch beads prepared by ionotropic gelation as potential matrices for controlled release of fertilizers.

    PubMed

    Perez, Jonas J; Francois, Nora J

    2016-09-01

    The present study examines the agrochemical application of macrospheres prepared with chitosan and chitosan-starch blends by an easy dripping technique, using a sodium tripolyphosphate aqueous solution as the crosslinking agent. These biopolymers form hydrogels that could be a viable alternative method to obtain controlled-release fertilizers (CRFs). Three different concentrations (ranging from 20 to 100wt/wt% of chitosan) and two crosslinking times (2 or 4h) were used. The resulting polymeric matrices were examined by scanning electron microscopy coupled with energy dispersive X-ray, X-ray diffraction, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance, thermogravimetric analysis and differential scanning calorimetry. Ionotropic gelation and neutralization induced the formation of the macrospheres. The crosslinking time and the composition of the polymeric hydrogel controlled the crosslinking degree, the swelling behavior and the fertilizer loading capability. Potassium nitrate-loaded beads were shown to be useful as a controlled-release fertilizer. After 14days of continuous release into distilled water, the cumulative concentration in the release medium reached between 70 and 93% of the initially loaded salt, depending on the matrix used. The prepared beads showed properties that make them suitable for use in the agrochemical industry as CRFs. PMID:27185124

  5. Achieving glycemic control in special populations in hospital: perspectives in practice.

    PubMed

    Cheng, Alice Y Y

    2014-04-01

    Achieving and maintaining glycemic control in patients with diabetes admitted to hospital is challenging because of the many competing factors of nutrition, pharmacotherapy and other patient-related and systemic factors. For patients receiving enteral or parenteral feeding, eating irregularly or receiving glucocorticoid therapy, the challenges are even greater. The basic principles to follow when managing glycemia in these populations are as follows: 1) Recognition of those at risk for hyperglycemia; 2) frequent bedside glucose monitoring; 3) a proactive approach with routine insulin administration based on the predicted glucose patterns; 4) constant reassessment of the glycemic status and titration of the routine insulin accordingly. PMID:24690508

  6. Semen controlled-release capsules allow a single artificial insemination in sows.

    PubMed

    Vigo, D; Faustini, M; Villani, S; Orsini, F; Bucco, M; Chlapanidas, T; Conte, U; Ellis, K; Torre, M L

    2009-09-01

    Controlled-release capsules containing boar spermatozoa were developed to extend the preservation time of spermatozoa and maximize the efficiency of a single artificial insemination. A large trial (4245 sows) was performed with these capsules using double/triple conventional artificial insemination as a control. The effect of treatment on pregnancy diagnosis, delivery, and born piglets was investigated, with allowance being made for considering season, spermatozoa amount, and the weaning-to-estrus interval as confounding variables. The same pregnancy rate and prolificacy were obtained by two insemination techniques, and a higher parturition frequency was reached with capsules. The reproductive performance in pigs has therefore been optimized by a single instrumental insemination with controlled-release capsules. PMID:19505716

  7. Fracturing fluid cleanup by controlled release of enzymes from polyelectrolyte complex nanoparticles

    NASA Astrophysics Data System (ADS)

    Barati Ghahfarokhi, Reza

    Guar-based polymer gels are used in the oil and gas industry to viscosify fluids used in hydraulic fracturing of production wells, in order to reduce leak-off of fluids and pressure, and improve the transport of proppants. After fracturing, the gel and associated filter cake must be degraded to very low viscosities using breakers to recover the hydraulic conductivity of the well. Enzymes are widely used to achieve this but injecting high concentrations of enzyme may result in premature degradation, or failure to gel; denaturation of enzymes at alkaline pH and high temperature conditions can also limit their applicability. In this study, application of polyelectrolyte nanoparticles for entrapping, carrying, releasing and protecting enzymes for fracturing fluids was examined. The objective of this research is to develop nano-sized carriers capable of carrying the enzymes to the filter cake, delaying the release of enzyme and protecting the enzyme against pH and temperature conditions inhospitable to native enzyme. Polyethylenimine-dextran sulfate (PEI-DS) polyelectrolyte complexes (PECs) were used to entrap two enzymes commonly used in the oil industry in order to obtain delayed release and to protect the enzyme from conditions inhospitable to native enzyme. Stability and reproducibility of PEC nanoparticles was assured over time. An activity measurement method was used to measure the entrapment efficiency of enzyme using PEC nanoparticles. This method was confirmed using a concentration measurement method (SDS-PAGE). Entrapment efficiencies of pectinase and a commercial high-temperature enzyme mixture in polyelectrolyte complex nanoparticles were maximized. Degradation, as revealed by reduction in viscoelastic moduli of borate-crosslinked hydroxypropyl guar (HPG) gel by commercial enzyme loaded in polyelectrolyte nanoparticles, was delayed, compared to equivalent systems where the enzyme mixture was not entrapped. This indicates that PEC nanoparticles delay the

  8. Controlling the release of active compounds from the inorganic carrier halloysite

    NASA Astrophysics Data System (ADS)

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-05-01

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  9. Controlling the release of active compounds from the inorganic carrier halloysite

    SciTech Connect

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-05-15

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  10. Coaxial electrospinning for encapsulation and controlled release of fragile water-soluble bioactive agents.

    PubMed

    Jiang, Hongliang; Wang, Liqun; Zhu, Kangjie

    2014-11-10

    Coaxial electrospinning is a robust technique for one-step encapsulation of fragile, water-soluble bioactive agents, including growth factors, DNA and even living organisms, into core-shell nanofibers. The coaxial electrospinning process eliminates the damaging effects due to direct contact of the agents with organic solvents or harsh conditions during emulsification. The shell layer serves as a barrier to prevent the premature release of the water-soluble core contents. By varying the structure and composition of the nanofibers, it is possible to precisely modulate the release of the encapsulated agents. Promising work has been done with coaxially electrospun non-woven mats integrated with bioactive agents for use in tissue engineering, in local delivery and in wound healing, etc. This paper reviews the origins of the coaxial electrospinning method, its updated status and potential future developments for controlled release of the class of fragile, water-soluble bioactive agents. PMID:24780265

  11. Controlled release and antibacterial activity of tetracycline hydrochloride-loaded bacterial cellulose composite membranes.

    PubMed

    Shao, Wei; Liu, Hui; Wang, Shuxia; Wu, Jimin; Huang, Min; Min, Huihua; Liu, Xiufeng

    2016-07-10

    Bacterial cellulose (BC) is widely used in biomedical applications. In this study, we prepared an antibiotic drug tetracycline hydrochloride (TCH)-loaded bacterial cellulose (BC) composite membranes, and evaluated the drug release, antibacterial activity and biocompatibility. The structure and morphology of the fabricated BC-TCH composite membranes were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TCH release results show that the incorporation of BC matrix to load TCH is able to control the release. In vitro antibacterial assay demonstrate that the developed BC-TCH composites displayed excellent antibacterial activity solely associated with the loaded TCH drug. More importantly, the BC-TCH composite membranes display good biocompatibility. These characteristics of BC-TCH composite membranes indicate that they may successfully serve as wound dressings and other medical biomaterials. PMID:27106158

  12. Multi-responsive magnetic microsphere of poly(N-isopropylacrylamide)/carboxymethylchitosan hydrogel for drug controlled release.

    PubMed

    Rodkate, Nantharak; Rutnakornpituk, Metha

    2016-10-20

    Multi-responsive composite microspheres were synthesized via an in situ free radical polymerization of thermo-responsive poly(N-isopropylacrylamide) (poly(NIPAAm)) in the presence of carboxymethylchitosan (CMC) and magnetite nanoparticles (MNPs) followed by glutaraldehyde crosslinking. Formulation conditions of the composite microspheres were tuned such that spherical microspheres with narrow size distributions were obtained (30.0±1.0μm in diameter). They responded well to an applied magnetic field and showed water swelling responses to the change in solution pH and temperature. The release of an entrapped indomethacin model drug was accelerated when the solution temperature was above its lower critical solution temperature (LCST) (50°C) or when the solution pH was in basic conditions (pH 11). These responsive properties can be used as triggering mechanisms for releases of the entrapped drugs from the microspheres, indicating their great potentials for use in controlled release applications. PMID:27474565

  13. Knowledge system and method for simulating chemical controlled release device performance

    DOEpatents

    Cowan, Christina E.; Van Voris, Peter; Streile, Gary P.; Cataldo, Dominic A.; Burton, Frederick G.

    1991-01-01

    A knowledge system for simulating the performance of a controlled release device is provided. The system includes an input device through which the user selectively inputs one or more data parameters. The data parameters comprise first parameters including device parameters, media parameters, active chemical parameters and device release rate; and second parameters including the minimum effective inhibition zone of the device and the effective lifetime of the device. The system also includes a judgemental knowledge base which includes logic for 1) determining at least one of the second parameters from the release rate and the first parameters and 2) determining at least one of the first parameters from the other of the first parameters and the second parameters. The system further includes a device for displaying the results of the determinations to the user.

  14. Biodegradable polymer based encapsulation of neem oil nanoemulsion for controlled release of Aza-A.

    PubMed

    Jerobin, Jayakumar; Sureshkumar, R S; Anjali, C H; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2012-11-01

    Azadirachtin a biological compound found in neem have medicinal and pesticidal properties. The present work reports on the encapsulation of neem oil nanoemulsion using sodium alginate (Na-Alg) by cross linking with glutaraldehyde. Starch and polyethylene glycol (PEG) were used as coating agents for smooth surface of beads. The SEM images showed beads exhibited nearly spherical shape. Swelling of the polymeric beads reduced with coating which in turn decreased the rate of release of Aza-A. Starch coated encapsulation of neem oil nanoemulsion was found to be effective when compared to PEG coated encapsulation of neem oil nanoemulsion. The release rate of neem Aza-A from the beads into an aqueous environment was analyzed by UV-visible spectrophotometer (214 nm). The encapsulated neem oil nanoemulsion have the potential for controlled release of Aza-A. Neem oil nanoemulsion encapsulated beads coated with PEG was found to be toxic in lymphocyte cells. PMID:22944443

  15. Controlled release behaviour of protein-loaded microparticles prepared via coaxial or emulsion electrospray

    PubMed Central

    Wang, Ying; Yang, Xiaoping; Liu, Wentao; Zhang, Feng; Cai, Qing; Deng, Xuliang

    2013-01-01

    Biodegradable poly (lactic-co-glycolic acid) (PLGA) microparticles are an effective way to achieve sustained drug release. In this study, we investigated a sustained release model of PLGA microparticles with incorporated protein via either emulsion or coaxial electrospray techniques. PLGA (75:25) was used as the carrier, and bovine serum albumin as a model protein. Coaxial electrospray resulted in a type of core–shell structure with mean diameters of 2.41 ± 0.60 µm and a centralised protein distribution within the core. Emulsion electrospray formed bigger microparticles with mean diameters of 22.75 ± 8.05 µm and a heterogeneous protein distribution throughout the microparticles. The coaxial electrospray microparticles presented a much slighter burst release than the emulsion electrospray microparticles. Loading efficiency was significantly higher (p < 0.05) in the coaxial group than emulsion group. This indicated that both emulsion and coaxial electrospray could produce protein-loaded microparticles with sustained release behaviour, but the former revealed a superior approach for drug delivery. PMID:23346923

  16. Esmolol in a case of severe tetanus. Adequate haemodynamic control achieved despite markedly elevated catecholamine levels.

    PubMed

    Beards, S C; Lipman, J; Bothma, P A; Joynt, G M

    1994-03-01

    A patient with severe tetanus, who had a sympathetic crisis while sedated with 30 mg/h diazepam and 30 mg/h morphine, is described. Satisfactory control of the haemodynamic crisis was achieved with bolus doses of esmolol to a total of 180 mg. A disturbing finding was that although there was adequate control of the tachycardia and hypertension, arterial catecholamine levels remained markedly elevated. Adrenaline levels of 531 pg/ml (normal 10-110 pg/ml) and noradrenaline levels of 1,036 pg/ml (normal 100-500 pg/ml) were recorded when the patient had a systolic arterial pressure of 110 mmHg and a heart rate of 97/min. The implications of this finding are discussed. PMID:11218441

  17. Dual Release Paracetamol in Osteoarthritis of Knee: A Randomized Controlled Clinical Trial

    PubMed Central

    Raj, D. Gokul; Sharma, Ateet B.; Swami B., Mallikarjun; Batra, Sumit; Acharya, Apurv; Maroo, Sanjaykumar H.; Patel, Ketan R.; Prajapati, Vipul

    2014-01-01

    Background: Paracetamol is recommended as first line agent for pain management in osteoarthritis (OA) by various guidelines. The main problem associated with management of osteoarthritis is long term patient compliance to paracetamol due to its frequent dosing. Objective: To evaluate the efficacy and safety of Paracetamol 650 mg dual release tablet twice daily (PCM 650 dual release) compared to paracetamol 500mg immediate release tablet thrice daily (PCM 500 IR) in the treatment of Knee OA. Materials and Methods: In this randomized, open label, parallel, active controlled clinical study, 250 patients of OA knee meeting inclusion criteria were randomized to receive either PCM 650 dual release two times daily or PCM 500 IR three times daily for 6 weeks. Patients were assessed at baseline, 2, 4 and 6 weeks. Primary efficacy measures were severity of pain (Visual Analogue Scale) and Knee injury and osteoarthritis outcome score (KOOS) subscale for pain at week 2, 4 and 6. Other KOOS subscales (symptoms other than pain, function in daily living, function in sport and recreation, quality of life) and patient’s and physicians global assessment of therapy were included as secondary endpoints. Results: Both treatment groups showed improvement in primary endpoints at each evaluation visit. Patients receiving PCM 650 dual release showed significant improvement of pain in both primary endpoints at each study visit compared to patients receiving PCM 500 IR (p<0.001). PCM 650 dual release was significantly superior to PCM 500 IR for improvement in all KOOS subscales at each study visit (p<0.01). Less number of patients required additional rescue analgesics in PCM 650 dual release group (16% patients vs 26%, PCM 500 IR; p>0.05). Adverse effects were significantly less in PCM 650 dual release group (6% vs. 14% in PCM 500 IR; p<0.05). Patient’s and physician’s global assessment of therapy favoured PCM 650 dual release than PCM 500 IR (p<0.001). Conclusion: Patients with

  18. Ethyl cellulose microcapsules for protecting and controlled release of folic acid.

    PubMed

    Prasertmanakit, Satit; Praphairaksit, Nalena; Chiangthong, Worawadee; Muangsin, Nongnuj

    2009-01-01

    Ethyl cellulose microcapsules were developed for use as a drug-delivery device for protecting folic acid from release and degradation in the undesirable environmental conditions of the stomach, whilst allowing its release in the intestinal tract to make it available for absorption. The controlled release folic acid-loaded ethyl cellulose microcapsules were prepared by oil-in-oil emulsion solvent evaporation using a mixed solvent system, consisting of a 9:1 (v/v) ratio of acetone:methanol and light liquid paraffin as the dispersed and continuous phase. Span 80 was used as the surfactant to stabilize the emulsion. Scanning electron microscopy revealed that the microcapsules had a spherical shape. However, the particulate properties and in vitro release profile depended on the concentrations of the ethyl cellulose, Span 80 emulsifier, sucrose (pore inducer), and folic acid. The average diameter of the microcapsules increased from 300 to 448 microm, whilst the folic acid release rate decreased from 52% to 40%, as the ethyl cellulose concentration was increased from 2.5% to 7.5% (w/v). Increasing the Span 80 concentration from 1% to 4% (v/v) decreased the average diameter of microcapsules from 300 to 141 microm and increased the folic acid release rate from 52% to 79%. The addition of 2.5-7.5% (w/v) of sucrose improved the folic acid release from the microcapsules. The entrapment efficiency was improved from 64% to 88% when the initial folic acid concentration was increased from 1 to 3 mg/ml. PMID:19763838

  19. The Effect of Automatic Gain Control Structure and Release Time on Cochlear Implant Speech Intelligibility

    PubMed Central

    Khing, Phyu P.; Swanson, Brett A.; Ambikairajah, Eliathamby

    2013-01-01

    Nucleus cochlear implant systems incorporate a fast-acting front-end automatic gain control (AGC), sometimes called a compression limiter. The objective of the present study was to determine the effect of replacing the front-end compression limiter with a newly proposed envelope profile limiter. A secondary objective was to investigate the effect of AGC speed on cochlear implant speech intelligibility. The envelope profile limiter was located after the filter bank and reduced the gain when the largest of the filter bank envelopes exceeded the compression threshold. The compression threshold was set equal to the saturation level of the loudness growth function (i.e. the envelope level that mapped to the maximum comfortable current level), ensuring that no envelope clipping occurred. To preserve the spectral profile, the same gain was applied to all channels. Experiment 1 compared sentence recognition with the front-end limiter and with the envelope profile limiter, each with two release times (75 and 625 ms). Six implant recipients were tested in quiet and in four-talker babble noise, at a high presentation level of 89 dB SPL. Overall, release time had a larger effect than the AGC type. With both AGC types, speech intelligibility was lower for the 75 ms release time than for the 625 ms release time. With the shorter release time, the envelope profile limiter provided higher group mean scores than the front-end limiter in quiet, but there was no significant difference in noise. Experiment 2 measured sentence recognition in noise as a function of presentation level, from 55 to 89 dB SPL. The envelope profile limiter with 625 ms release time yielded better scores than the front-end limiter with 75 ms release time. A take-home study showed no clear pattern of preferences. It is concluded that the envelope profile limiter is a feasible alternative to a front-end compression limiter. PMID:24312408

  20. [Study on self-microemulsifying membrane controlled-release drop pill of hawthorn leaves flavonoids].

    PubMed

    Wang, Jin-Xuan; Huang, Hong-Zhang; Li, Ning; Gao, Chong-Kai

    2014-03-01

    To prepare the hawthorn leaves flavonoids self-microemulsifying membrane controlled-release coated drop pill, and to study its release rate in vitro and pharmacokinetics study in vivo. In order to improve the dissolution of hawthorn leaves flavonoids, self-microemulsifying technology was used to prepare the hawthorn leaves flavonoids self-microemulsion. Hawthorn leaves flavonoids self-microemulsifying drop pill was prepared with the PEG 6000. Studies were made on the in vitro release of flavonoids from hawthorn leaves self-micro-emulsifying membrane-moderated coated drop pills and the in vivo pharmacokinetic in rats. The prescription of flavonoids from hawthorn leaves self-micro-emulsifying drop pills was 0.25 g of flavonoids from hawthorn leaves, 0.25 g of iodophenyl maleimide, 0.375 g of polyethylene glycol 400, 0.375 g of cremophor RH 40 and 2 g of polyethylene glycol 6000. The optimized prescription was 4 g of ethyl cellulose 20, 0.64 g of polyethylene glycol 400, 1.8 g of diethyl phthalate, and the weight of coating materials increased by 3.5%. Flavonoids from hawthorn leaves self-micro-emulsifying membrane-moderated coated drop pills complied with the design of sustained-release in 12 h in terms of in vitro release and in vivo pharmacokinetic parameters in rats, and its bioavailability was 2.47 times of quick-release drop pills. Slightly soluble flavonoids from hawthorn leaves could be made into sustained-release preparations by the self-micro-emulsifying and coating technology. PMID:25204172