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Sample records for crystal biosensor microplates

  1. Photonic crystal biosensor microplates with integrated fluid networks for high throughput applications in drug discovery

    NASA Astrophysics Data System (ADS)

    Choi, Charles J.; Chan, Leo L.; Pineda, Maria F.; Cunningham, Brian T.

    2007-09-01

    Assays used in pharmaceutical research require a system that can not only detect biochemical interactions with high sensitivity, but that can also perform many measurements in parallel while consuming low volumes of reagents. While nearly all label-free biosensor transducers to date have been interfaced with a flow channel, the liquid handling system is typically aligned and bonded to the transducer for supplying analytes to only a few sensors in parallel. In this presentation, we describe a fabrication approach for photonic crystal biosensors that utilizes nanoreplica molding to produce a network of sensors that are automatically self-aligned with a microfluidic network in a single process step. The sensor/fluid network is inexpensively produced on large surface areas upon flexible plastic substrates, allowing the device to be incorporated into standard format 96-well microplates. A simple flow scheme using hydrostatic pressure applied through a single control point enables immobilization of capture ligands upon a large number of sensors with 220 nL of reagent, and subsequent exposure of the sensors to test samples. A high resolution imaging detection instrument is capable of monitoring the binding within parallel channels at rates compatible with determining kinetic binding constants between the immobilized ligands and the analytes. The first implementation of this system is capable of monitoring the kinetic interactions of 11 flow channels at once, and a total of 88 channels within an integrated biosensor microplate in rapid succession. The system was initially tested to characterize the interaction between sets of proteins with known binding behavior.

  2. Microplate based optical biosensor for L-Dopa using tyrosinase from Amorphophallus campanulatus.

    PubMed

    Saini, Amardeep Singh; Kumar, Jitendra; Melo, Jose Savio

    2014-11-01

    Developing a biosensor which is capable of simultaneously monitoring l-Dopa levels in multiple samples besides requiring small reaction volume is of great value. The present study describes the detection of l-Dopa using tyrosinase enzyme extracted from Amorphophallus campanulatus and immobilized on the surface of the microplate wells. Among the different approaches used for immobilizing tyrosinase onto the microplate wells, glutaraldehyde treatment was found to be most effective. Besides enzyme activity, ESEM-EDS (environmental scanning electron microscope-energy dispersive system) and Atomic Force Microscopy (AFM) were also carried out to confirm the immobilization of tyrosinase enzyme onto the microplate well surface. This immobilized biocomponent was then integrated with an optical transducer for l-Dopa detection and it showed good reproducibility. The sensing property of the system was studied by measuring the initial rate of dopachrome formation at 475 nm. The calibration plot gave a linear range of detection from 10-1000 μM and the detection limit was calculated to be 3 μM. The immobilized biocomponent was stable for 41 days and was reused up to nine times. Spiked samples (blood plasma) were also analyzed using this biocomponent. This microplate based biosensor thus provides a convenient system for detection of multiple samples in a single run. PMID:25300217

  3. Slotted photonic crystal biosensors

    NASA Astrophysics Data System (ADS)

    Scullion, Mark Gerard

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them result in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This thesis presents a new platform for optical biosensors, namely slotted photonic crystals, which engender higher sensitivities due to their ability to confine, spatially and temporally, the peak of optical mode within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. High sensitivities were observed in smaller structures than most competing devices in the literature. Initial tests with cellular material for real applications was also performed, and shown to be of promise. In addition, groundwork to make an integrated device that includes the spectrometer function was also carried out showing that slotted photonic crystals themselves can be used for on-chip wavelength specific filtering and spectroscopy, whilst gas-free microvalves for automation were also developed. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.

  4. Photonic Crystal Nanolaser Biosensors

    NASA Astrophysics Data System (ADS)

    Kita, Shota; Otsuka, Shota; Hachuda, Shoji; Endo, Tatsuro; Imai, Yasunori; Nishijima, Yoshiaki; Misawa, Hiroaki; Baba, Toshihiko

    High-performance and low-cost sensors are critical devices for high-throughput analyses of bio-samples in medical diagnoses and life sciences. In this paper, we demonstrate photonic crystal nanolaser sensor, which detects the adsorption of biomolecules from the lasing wavelength shift. It is a promising device, which balances a high sensitivity, high resolution, small size, easy integration, simple setup and low cost. In particular with a nanoslot structure, it achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors. Our investigations indicate that the nanoslot acts as a protein condenser powered by the optical gradient force, which arises from the strong localization of laser mode in the nanoslot.

  5. Work function engineering of SnO single crystal microplates with thermal annealing.

    PubMed

    Doh, Won Hui; Jeong, Wooseok; Lee, Hyunsoo; Park, Jonghyurk; Park, Jeong Young

    2016-08-19

    We synthesized black SnO single-crystal microplates via a sonochemical process and engineered the work function of the SnO microplates using thermal treatments. The as-synthesized SnO microplates have a wide (001) plane, as is clearly evident from TEM images and diffraction patterns. Surface potential measurements on the SnO microplates show that the work function changes as the annealing temperature increases. The TEM and XAS results after thermal treatments imply that the micro-sized SnO(001) single-crystals are stable up to about 400 °C in air, after which the surface starts to become locally oxidized. Consequently, the long-range ordering and lattice parameter of the SnO(001) single crystals started to change to make polycrystalline SnO2 at about 600 °C. These results demonstrate the ability to tune the work function of the microplates and suggest an intriguing way to engineer the electrical properties of nanostructures. PMID:27389518

  6. Work function engineering of SnO single crystal microplates with thermal annealing

    NASA Astrophysics Data System (ADS)

    Doh, Won Hui; Jeong, Wooseok; Lee, Hyunsoo; Park, Jonghyurk; Park, Jeong Young

    2016-08-01

    We synthesized black SnO single-crystal microplates via a sonochemical process and engineered the work function of the SnO microplates using thermal treatments. The as-synthesized SnO microplates have a wide (001) plane, as is clearly evident from TEM images and diffraction patterns. Surface potential measurements on the SnO microplates show that the work function changes as the annealing temperature increases. The TEM and XAS results after thermal treatments imply that the micro-sized SnO(001) single-crystals are stable up to about 400 °C in air, after which the surface starts to become locally oxidized. Consequently, the long-range ordering and lattice parameter of the SnO(001) single crystals started to change to make polycrystalline SnO2 at about 600 °C. These results demonstrate the ability to tune the work function of the microplates and suggest an intriguing way to engineer the electrical properties of nanostructures.

  7. Wafer-scale growth of large arrays of perovskite microplate crystals for functional electronics and optoelectronics

    PubMed Central

    Wang, Gongming; Li, Dehui; Cheng, Hung-Chieh; Li, Yongjia; Chen, Chih-Yen; Yin, Anxiang; Zhao, Zipeng; Lin, Zhaoyang; Wu, Hao; He, Qiyuan; Ding, Mengning; Liu, Yuan; Huang, Yu; Duan, Xiangfeng

    2015-01-01

    Methylammonium lead iodide perovskite has attracted intensive interest for its diverse optoelectronic applications. However, most studies to date have been limited to bulk thin films that are difficult to implement for integrated device arrays because of their incompatibility with typical lithography processes. We report the first patterned growth of regular arrays of perovskite microplate crystals for functional electronics and optoelectronics. We show that large arrays of lead iodide microplates can be grown from an aqueous solution through a seeded growth process and can be further intercalated with methylammonium iodide to produce perovskite crystals. Structural and optical characterizations demonstrate that the resulting materials display excellent crystalline quality and optical properties. We further show that perovskite crystals can be selectively grown on prepatterned electrode arrays to create independently addressable photodetector arrays and functional field effect transistors. The ability to grow perovskite microplates and to precisely place them at specific locations offers a new material platform for the fundamental investigation of the electronic and optical properties of perovskite materials and opens a pathway for integrated electronic and optoelectronic systems. PMID:26601297

  8. Optical modeling of liquid crystal biosensors

    NASA Astrophysics Data System (ADS)

    Hwang, Dae Kun; Rey, Alejandro D.

    2006-11-01

    Optical simulations of a liquid crystal biosensor device are performed using an integrated optical/textural model based on the equations of nematodynamics and two optical methods: the Berreman optical matrix method [J. Opt. Soc. Am. 62, 502 (1972)] and the discretization of the Maxwell equations based on the finite difference time domain (FDTD) method. Testing the two optical methods with liquid crystal films of different degrees of orientational heterogeneities demonstrates that only the FDTD method is suitable to model this device. Basic substrate-induced texturing process due to protein adsorption gives rise to an orientation correlation function that is nearly linear with the transmitted light intensity, providing a basis to calibrate the device. The sensitivity of transmitted light to film thickness, protein surface coverage, and wavelength is established. A crossover incident light wavelength close to λco≈500nm is found, such that when λ >λco thinner films are more sensitive to the amount of protein surface coverage, while for λ <λco the reverse holds. In addition it is found that for all wavelengths the sensitivity increases with the amount of protein coverage. The integrated device model based on FDTD optical simulations in conjunction with the Landau-de Gennes nematodynamics model provides a rational basis for further progress in liquid crystal biosensor devices.

  9. Highly sensitive bovine serum albumin biosensor based on liquid crystal

    NASA Astrophysics Data System (ADS)

    Sharma, Vikash; Kumar, Ajay; Ganguly, Prasun; Biradar, A. M.

    2014-01-01

    A highly sensitive liquid crystal (LC) based bovine serum albumin (BSA) protein biosensor is designed. A uniform homeotropic alignment of nematic LC was observed in BSA free substrate which changed into homogeneous in presence of BSA. The change in the LC orientation is found to depend strongly on BSA concentration. This change in the LC alignment is attributed to the modification in the surface conditions which is verified by contact angle measurements. We have detected an ultra low concentration (0.5 μg/ml) of BSA. The present study demonstrates the utilization of LC in the realization of high sensitivity biosensors.

  10. Size-dependent phase transition in methylammonium lead iodide perovskite microplate crystals

    NASA Astrophysics Data System (ADS)

    Li, Dehui; Wang, Gongming; Cheng, Hung-Chieh; Chen, Chih-Yen; Wu, Hao; Liu, Yuan; Huang, Yu; Duan, Xiangfeng

    2016-04-01

    Methylammonium lead iodide perovskite has attracted considerable recent interest for solution processable solar cells and other optoelectronic applications. The orthorhombic-to-tetragonal phase transition in perovskite can significantly alter its optical, electrical properties and impact the corresponding applications. Here, we report a systematic investigation of the size-dependent orthorhombic-to-tetragonal phase transition using a combined temperature-dependent optical, electrical transport and transmission electron microscopy study. Our studies of individual perovskite microplates with variable thicknesses demonstrate that the phase transition temperature decreases with reducing microplate thickness. The sudden decrease of mobility around phase transition temperature and the presence of hysteresis loops in the temperature-dependent mobility confirm that the orthorhombic-to-tetragonal phase transition is a first-order phase transition. Our findings offer significant fundamental insight on the temperature- and size-dependent structural, optical and charge transport properties of perovskite materials, and can greatly impact future exploration of novel electronic and optoelectronic devices from these materials.

  11. Size-dependent phase transition in methylammonium lead iodide perovskite microplate crystals.

    PubMed

    Li, Dehui; Wang, Gongming; Cheng, Hung-Chieh; Chen, Chih-Yen; Wu, Hao; Liu, Yuan; Huang, Yu; Duan, Xiangfeng

    2016-01-01

    Methylammonium lead iodide perovskite has attracted considerable recent interest for solution processable solar cells and other optoelectronic applications. The orthorhombic-to-tetragonal phase transition in perovskite can significantly alter its optical, electrical properties and impact the corresponding applications. Here, we report a systematic investigation of the size-dependent orthorhombic-to-tetragonal phase transition using a combined temperature-dependent optical, electrical transport and transmission electron microscopy study. Our studies of individual perovskite microplates with variable thicknesses demonstrate that the phase transition temperature decreases with reducing microplate thickness. The sudden decrease of mobility around phase transition temperature and the presence of hysteresis loops in the temperature-dependent mobility confirm that the orthorhombic-to-tetragonal phase transition is a first-order phase transition. Our findings offer significant fundamental insight on the temperature- and size-dependent structural, optical and charge transport properties of perovskite materials, and can greatly impact future exploration of novel electronic and optoelectronic devices from these materials. PMID:27098114

  12. Size-dependent phase transition in methylammonium lead iodide perovskite microplate crystals

    DOE PAGESBeta

    Li, Dehui; Wang, Gongming; Cheng, Hung -Chieh; Chen, Chih -Yen; Wu, Hao; Liu, Yuan; Huang, Yu; Duan, Xiangfeng

    2016-04-21

    Methylammonium lead iodide perovskite has attracted considerable recent interest for solution processable solar cells and other optoelectronic applications. The orthorhombic-to-tetragonal phase transition in perovskite can significantly alter its optical, electrical properties and impact the corresponding applications. Here, we report a systematic investigation of the size-dependent orthorhombic-to-tetragonal phase transition using a combined temperature-dependent optical, electrical transport and transmission electron microscopy study. Our studies of individual perovskite microplates with variable thicknesses demonstrate that the phase transition temperature decreases with reducing microplate thickness. The sudden decrease of mobility around phase transition temperature and the presence of hysteresis loops in the temperature-dependent mobility confirmmore » that the orthorhombic-to-tetragonal phase transition is a first-order phase transition. Lastly, our findings offer significant fundamental insight on the temperature-and size-dependent structural, optical and charge transport properties of perovskite materials, and can greatly impact future exploration of novel electronic and optoelectronic devices from these materials.« less

  13. Size-dependent phase transition in methylammonium lead iodide perovskite microplate crystals

    PubMed Central

    Li, Dehui; Wang, Gongming; Cheng, Hung-Chieh; Chen, Chih-Yen; Wu, Hao; Liu, Yuan; Huang, Yu; Duan, Xiangfeng

    2016-01-01

    Methylammonium lead iodide perovskite has attracted considerable recent interest for solution processable solar cells and other optoelectronic applications. The orthorhombic-to-tetragonal phase transition in perovskite can significantly alter its optical, electrical properties and impact the corresponding applications. Here, we report a systematic investigation of the size-dependent orthorhombic-to-tetragonal phase transition using a combined temperature-dependent optical, electrical transport and transmission electron microscopy study. Our studies of individual perovskite microplates with variable thicknesses demonstrate that the phase transition temperature decreases with reducing microplate thickness. The sudden decrease of mobility around phase transition temperature and the presence of hysteresis loops in the temperature-dependent mobility confirm that the orthorhombic-to-tetragonal phase transition is a first-order phase transition. Our findings offer significant fundamental insight on the temperature- and size-dependent structural, optical and charge transport properties of perovskite materials, and can greatly impact future exploration of novel electronic and optoelectronic devices from these materials. PMID:27098114

  14. Optical detection of sepsis markers using liquid crystal based biosensors

    NASA Astrophysics Data System (ADS)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  15. A liquid-crystal-based DNA biosensor for pathogen detection

    NASA Astrophysics Data System (ADS)

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-03-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

  16. A liquid-crystal-based DNA biosensor for pathogen detection.

    PubMed

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection. PMID:26940532

  17. A liquid-crystal-based DNA biosensor for pathogen detection

    PubMed Central

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection. PMID:26940532

  18. Photonic crystal biosensor based on optical surface waves.

    PubMed

    Konopsky, Valery N; Karakouz, Tanya; Alieva, Elena V; Vicario, Chiara; Sekatskii, Sergey K; Dietler, Giovanni

    2013-01-01

    A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately. PMID:23429517

  19. Biosensors.

    ERIC Educational Resources Information Center

    Rechnitz, Garry A.

    1988-01-01

    Describes theory and principles behind biosensors that incorporate biological components as part of a sensor or probe. Projects major applications in medicine and veterinary medicine, biotechnology, food and agriculture, environmental studies, and the military. Surveys current use of biosensors. (ML)

  20. Silicon photonic crystal resonators for label free biosensor

    NASA Astrophysics Data System (ADS)

    Sana, Amrita Kumar; Honzawa, Keita; Amemiya, Yoshiteru; Yokoyama, Shin

    2016-04-01

    We report the fabrication and characterization of a two-dimensional (2D) silicon photonic crystal biosensor consisting of waveguides and cavity-type and defect-type resonators for enhancing the interactions between light and biomaterials. Sensitivity was measured using sucrose solution and the sensor showed the highest sensitivity [1570 nm/RIU (refractive index unit)] ever reported. We also investigated cavity size effects on resonance wavelength shift, and we observed that a large cavity exhibits a greater resonance wavelength shift. The fabricated sensor has shown a high Q of ∼105 in water and a device figure of merit of 1.2 × 105, which represent the improvements of the device performance over other photonic-crystal-based sensors.

  1. Low-cost and highly efficient DNA biosensor for heavy metal ion using specific DNAzyme-modified microplate and portable glucometer-based detection mode.

    PubMed

    Zhang, Jin; Tang, Ying; Teng, Liumei; Lu, Minghua; Tang, Dianping

    2015-06-15

    A simple and low-cost DNA sensing platform based on Pb(2+)-specific DNAzyme-modified microplate was successfully developed for highly sensitive monitoring of lead ion (Pb(2+), one kind of toxic heavy metal ion) in the environmental samples coupling with a portable personal glucometer (PGM)-based detection mode. The detection cell was first prepared simply by means of immobilizing the DNAzyme on the streptavidin-modified microplate. Gold nanoparticle labeled with single-stranded DNA and invertase (Enz-AuNP-DNA) was utilized as the signal-transduction tag to produce PGM substrate (glucose). Upon addition of lead ion into the microplate, the substrate strand of the immobilized DNAzyme was catalytically cleaved by target Pb(2+), and the newly generated single-strand DNA in the microplate could hybridize again with the single-stranded DNA on the Enz-AuNP-DNA. Accompanying with the Enz-AuNP-DNA, the carried invertase could convert sucrose into glucose. The as-produced glucose could be monitored by using a widely accessible PGM for in situ amplified digital readout. Based on Enz-AuNP-DNA amplification strategy, as low as 1.0 pM Pb(2+) could be detected under the optimal conditions. Moreover, the methodology also showed good reproducibility and high selectivity toward target Pb(2+) against other metal ions because of highly specific Pb(2+)-dependent DNAzyme, and was applicable for monitoring Pb(2+) in the naturally contaminated sewage and spiked drinking water samples. PMID:25576929

  2. Liquid crystal-based proton sensitive glucose biosensor.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2014-02-01

    A transmission electron microscopy (TEM) grid filled with 4-cyno-4-pentylbiphenyl (5CB) on the octadecyltrichloro silane-coated glass in an aqueous medium was developed to construct a glucose biosensor by coating poly(acrylicacid-b-4-cynobiphenyl-4-oxyundecylacrylate) (PAA-b-LCP) at the aqueous/5CB interface and immobilizing glucose oxidase (GOx) covalently to the PAA chains. The glucose was detected from a homeotropic to planar orientational transition of 5CB by polarized optical microscopy under crossed polarizers. The maximum immobilization density of the GOx, 1.3 molecules/nm(2) obtained in this TEM grid cell enabled the detection of glucose at concentrations as low as 0.02 mM with a response time of 10 s. This liquid crystal-based glucose sensor provided a linear response of birefringence of the 5CB to glucose concentrations ranging from 0.05 to 2 mM with a Michaelis-Menten constant (Km) of 0.32 mM. This new and sensitive glucose biosensor has the merits of low production cost and easy detection through the naked eye and might be useful for prescreening the glucose level in the human body. PMID:24432733

  3. Gold nanoparticle based signal enhancement liquid crystal biosensors for DNA hybridization assays.

    PubMed

    Yang, Shengyuan; Liu, Yanmei; Tan, Hui; Wu, Chao; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2012-03-18

    A novel signal enhanced liquid crystal biosensor based on using AuNPs for highly sensitive DNA detection has been developed. This biosensor not only significantly decreases the detection limit, but also offers a simple detection process and shows a good selectivity to distinguish perfectly matched target DNA from two-base mismatched DNA. PMID:22302154

  4. Photonic Crystal Biosensor with In-Situ Synthesized DNA Probes for Enhanced Sensitivity

    SciTech Connect

    Hu, Shuren; Zhao, Y.; Retterer, Scott T; Kravchenko, Ivan I; Weiss, Sharon

    2013-01-01

    We report on a nearly 8-fold increase in multi-hole defect photonic crystal biosensor response by incorporating in-situ synthesis of DNA probes, as compared to the conventional functionalization method employing pre-synthesized DNA probe immobilization.

  5. Liquid crystal based biosensors for bile acid detection

    NASA Astrophysics Data System (ADS)

    He, Sihui; Liang, Wenlang; Tanner, Colleen; Fang, Jiyu; Wu, Shin-Tson

    2013-03-01

    The concentration level of bile acids is a useful indicator for early diagnosis of liver diseases. The prevalent measurement method in detecting bile acids is the chromatography coupled with mass spectrometry, which is precise yet expensive. Here we present a biosensor platform based on liquid crystal (LC) films for the detection of cholic acid (CA). This platform has the advantage of low cost, label-free, solution phase detection and simple analysis. In this platform, LC film of 4-Cyano-4'-pentylbiphenyl (5CB) was hosted by a copper grid supported with a polyimide-coated glass substrate. By immersing into sodium dodecyl sulfate (SDS) solution, the LC film was coated with SDS which induced a homeotropic anchoring of 5CB. Addition of CA introduced competitive adsorption between CA and SDS at the interface, triggering a transition from homeotropic to homogeneous anchoring. The detection limit can be tuned by changing the pH value of the solution from 12uM to 170uM.

  6. Thiol- and biotin-labeled probes for oligonucleotide quartz crystal microbalance biosensors of microalga alexandrium minutum.

    PubMed

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  7. Thiol- and Biotin-Labeled Probes for Oligonucleotide Quartz Crystal Microbalance Biosensors of Microalga Alexandrium Minutum

    PubMed Central

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  8. Nano-optic label-free biosensors based on photonic crystal platform with negative refraction

    NASA Astrophysics Data System (ADS)

    Aroua, W.; Haxha, S.; AbdelMalek, F.

    2012-04-01

    In this paper, a novel biosensor based on hetero photonic crystal (PC) structures is proposed. The biosensor consists of photonic crystals with negative refraction (PCNR) embedded between two ordinary PC structures. The PCNR is employed in order to produce an image that is as similar as the light source, which is located in the first ordinary PC. Significant enhancement of the image is achieved when a nanocavity is introduced into the PCNR. It is found that the transmission peak shifts when the nanocavity is filled with blood plasma, liquid and dry air. It is shown that by careful selection of the radius of the nanocavity, the sensitivity of the proposed biosensor can be enhanced. The presented PCNR biosensor is investigated by employing the finite-difference time-domain method (FDTD).

  9. BIOSENSORS

    EPA Science Inventory

    It has recently been proposed under the International Union of Pure and Applied Chemistry (IUPAC) Commission that biosensors be regarded as a subgroup of chemical sensors in which a biologically based mechanism is used for detection of the analyte. hemical sensors are defined und...

  10. Low-cost label-free biosensors using photonic crystals embedded between crossed polarizers.

    PubMed

    Nazirizadeh, Yousef; Bog, Uwe; Sekula, Sylwia; Mappes, Timo; Lemmer, Uli; Gerken, Martina

    2010-08-30

    There is a strong need for low-cost biosensors to enable rapid, on-site analysis of biological, biomedical, or chemical substances. We propose a platform for label-free optical biosensors based on applying the analyte onto a surface-functionalized photonic crystal slab and performing a transmission measurement with two crossed polarization filters. This dark-field approach allows for efficient background suppression as only the photonic crystal guided-mode resonances interacting with the functionalized surface experience significant polarization rotation. We present a compact biosensor demonstrator using a low-cost light emitting diode and a simple photodiode capable of detecting the binding kinetics of a 2.5 nM solution of the protein streptavidin on a biotin-functionalized photonic crystal surface. PMID:20940807

  11. Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon

    PubMed Central

    Chakravarty, Swapnajit; Zou, Yi; Lai, Wei-Cheng; Chen, Ray T.

    2012-01-01

    Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ~9,300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 picograms/mm2 Highest sensitivity, irrespective of the dissociation constant Kd, is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1μg/ml. PMID:22748964

  12. Four-channel label-free photonic crystal biosensor using nanocavity resonators

    NASA Astrophysics Data System (ADS)

    Olyaee, Saeed; Najafgholinezhad, Samira; Alipour Banaei, Hamed

    2013-09-01

    In this paper, we design and characterize a novel small size four-channel biosensor based on the two-dimensional photonic crystal with introducing waveguides and nano-cavities in the hexagonal lattice of air pores in the silicon slab. By removing a group of air pores, waveguides are achieved, and nano-cavities are shaped by modifying the radius of air pores. Highly parallel operation of this biosensor due to the special architecture is the capability of the designed structure. The biomaterials which are suspended in a liquid medium inside nano-cavities cause effective refractive index changes which lead to the resonant wavelength shift in the output terminal. According to results, with increasing the refractive index of nano-cavities, resonant wavelengths shifts to longer values. For biochemical sensing like DNA molecule and protein and for the refractive index detection, this novel designed biosensor can be utilized.

  13. Active layer identification of photonic crystal waveguide biosensor chip for the detection of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Painam, Balveer; Kaler, Rajinder S.; Kumar, Mukesh

    2016-07-01

    This work represents experimental and simulation analysis of photonic crystal waveguide (PCW)-based biosensor structures, which is used for detection of the Escherichia coli (E. coli) cell. A method is adopted for E. coli culture to measure length, diameter, and refractive index to finalize the structural design and to verify the suitability of PCW as a biosensor. This method is tested using DH5α strains of E. coli. The typical precisions of measurements are varied in ranges from 1.132 to 1.825 μm and from 0.447 to 0.66 μm for pathogen's length and diameter, respectively. The measured distribution of samples over length and diameter are in correlation with the measurements performed by scanning electron microscope. After obtaining average length and diameter of cylindrical shaped E. coli cell, we consider these values for simulation analysis of designed PCW biosensor. E. coli cell is trapped in the middle of the PCW biosensor having three different types of waveguides, i.e., gallium arsenide/silicon dioxide (GaAs/SiO2), silicon/silicon dioxide (Si/SiO2), or silicon nitride/silicon dioxide (Si3N4/SiO2) to observe the maximum resonance shift and sensitivity. It is observed from the simulation data analysis that GaAs/SiO2 is the preferred PCW biosensor for the identification of E. coli.

  14. Planar Photonic Crystal Biosensor for Quantitative Label-Free Cell Attachment Microscopy

    PubMed Central

    Chen, Weili; Long, Kenneth D.; Kurniawan, Jonas; Hung, Margaret; Yu, Hojeong; Harley, Brendan A.

    2016-01-01

    In this study, a planar-surface photonic crystal (PC) biosensor for quantitative, kinetic, label-free imaging of cell–surface interactions is demonstrated. The planar biosensor surface eliminates external stimuli to the cells caused by substrate topography to more accurately reflect smooth surface environment encountered by many cell types in vitro. Here, a fabrication approach that combines nanoreplica molding and a horizontal dipping process is used to planarize the surface of the PC biosensor. The planar PC biosensor maintains a high detection sensitivity that enables the monitoring of live cell–substrate interactions with spatial resolution sufficient for observing intracellular attachment strength gradients and the extensions of filopodia from the cell body. The evolution of cell morphology during the attachment and spreading process of 3T3 fibroblast cells is compared between planar and grating-structured PC biosensors. The planar surface effectively eliminates the directionally biased cellular attachment behaviors that are observed on the grating-structured surface. This work represents an important step forward in the development of label-free techniques for observing cellular processes without unintended external environmental modulation. PMID:26877910

  15. An immuno-biosensor system based on quartz crystal microbalance for avian influenza virus detection

    NASA Astrophysics Data System (ADS)

    Liu, Shengping; Chen, Guoming; Zhou, Qi; Wei, Yunlong

    2007-12-01

    For the quick detection of Avian Influenza Virus (AIV), a biosensor based on Quartz Crystal Microbalance (QCM) was fabricated according to the specific bonding principle between antibody and antigen. Staphylococcal Protein A (SPA) was extracted from Staphylococcus and purified. Then SPA was coated on the surface of QCM for immobilizing AIV monoclonal antibodies. The use of AIV monoclonal antibody could enhance the specificity of the immuno-biosensor. A multi-channel piezoelectricity detection system for the immuno-biosensor was developed. The system can work for the quick detection of AIV antigen in the case of the entirely aqueous status owe to one special oscillating circuit designed in this work. The optimum conditions of SPA coating and AIV monoclonal antibody immobilization were investigated utilizing the multi-channel detection system. The preliminary application of the immuno-biosensor system for detection of AIV was evaluated. Results indicate that the immuno-biosensor system can detect the AIV antigens with a linear range of 3-200ng/ml. The system can accomplish the detection of AIV antigens around 40 minutes.

  16. The Galapagos Microplate Revealed

    NASA Astrophysics Data System (ADS)

    Smith, D. K.; Schouten, H.; Cann, J. R.; Zhu, W.; Montesi, L. G.; Mitchell, G. A.

    2009-12-01

    We report a new bathymetry survey of the Galapagos microplate (GMP), which separates the Pacific, Nazca, and Cocos plates at the Galapagos Triple Junction. Prior to the formation of the microplate, 1.5-1.0 Ma, there was a succession of transient minor rifts forming triple junctions north and south of the propagating Cocos-Nazca rift (see Schouten et al. abstract). As proposed by Lonsdale (1988) the formation of a large near-axis seamount coincided with the initiation of the GMP and stabilized rifting on its southern boundary, now called Dietz Deep Rift. Lonsdale also proposed that the GMP was rotating clockwise at 6 degrees/my. Schouten et al. (1993) and Klein et al. (2005) applied an edge-driven microplate model to the GMP to understand its kinematics and predicted rotation rates of 30-40 degrees/my and 22 degrees/my, respectively. These interpretations and predictions were based on sparse bathymetry data. In early 2009 (AT 15-41), we mapped the Galapagos microplate in its entirety to understand more fully the conditions that led to the stabilization of the southern triple junction at Dietz Deep Rift and to constrain the rotation rate of the microplate. Our new data show the two highly contrasted sections of Dietz Deep Rift. The northeastern section contains Dietz Deep, a 2 km deep basin, within a fault-dominated rift valley about 20 km wide; subsidiary rifts occur to the south. Sidescan data indicate that extension in this broadly rifted area has been largely amagmatic. The southwestern section of Dietz Deep Rift is dominated by a variety of volcanic constructions in which faulting plays a minor part. The volcanism has resulted in two large seamounts and a number of volcanic ridges running parallel to the fault dominated rift valley. The largest volcanic ridge is steep-sided and straight, and extends to intersect the East Pacific Rise (EPR) at 1 10’N to form the triple junction. Other minor volcanic ridges occur in the SW section of the microplate fanning

  17. Quartz crystal microbalance (QCM) as biosensor for the detecting of Escherichia coli O157:H7

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Giang Nguyen, Dang; Phuong Uyen Nguyen, Hoang; Tran, Van Man; Nguyen, Thi Khoa My; Phat Huynh, Trong; Lam, Quang Vinh; Dat Huynh, Thanh; Truong, Thi Ngoc Lien

    2014-12-01

    Although Escherichia coli (E. coli) is a commensalism organism in the intestine of humans and warm-blooded animals, it can be toxic at higher density and causes diseases, especially the highly toxic E. coli O157:H7. In this paper a quartz crystal microbalance (QCM) biosensor was developed for the detection of E. coli O157:H7 bacteria. The anti-E. coli O157:H7 antibodies were immobilized on a self-assembly monolayer (SAM) modified 5 MHz AT-cut quartz crystal resonator. The SAMs were activated with 16-mercaptopropanoic acid, in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and ester N-hydroxysuccinimide (NHS). The result of changing frequency due to the adsorption of E. coli O157:H7 was measured by the QCM biosensor system designed and fabricated by ICDREC-VNUHCM. This system gave good results in the range of 102-107 CFU mL-1 E. coli O157:H7. The time of bacteria E. coli O157:H7 detection in the sample was about 50 m. Besides, QCM biosensor from SAM method was comparable to protein A method-based piezoelectric immunosensor in terms of the amount of immobilized antibodies and detection sensitivity.

  18. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    SciTech Connect

    Yan, Hai Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  19. Fluctuating hydrodynamics of nematics for models of liquid-crystal based biosensors via lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Guzman, Orlando; Velez, Jose Antonio; Castañeda, David

    2008-03-01

    Experimental biosensors based on liquid crystals (LC) use nematics to detect the presence of specific analytes, via the optical textures exhibited by the LC at long times. Efforts to model the time evolution of these textures have relied on relaxational models, ignoring transport phenomena. In this work we include hydrodynamics into a model for these LC biosensors, using lattice Boltzmann (LB) methods and assess the effect on the lifetime of multidomain structures, characteristic of high concentrations of analyte. We apply Yeoman's et al. LB algorithm, which reproduces the hydrodynamic equations developed by Beris and Edwards for LCs. We also take into account thermal fluctuations, by adding random perturbations to the hydrodynamic modes. Following Adhikari et al., their amplitude is determined by the Fluctuation-Dissipation theorem and we excite both hydrodynamic and the sub-hydrodynamic modes (also called ghost modes). As a result, we analyze the influence of the fluctuations and hydrodynamics on the movement of topological defects.

  20. Label-Free Biosensor Imaging on Photonic Crystal Surfaces

    PubMed Central

    Zhuo, Yue; Cunningham, Brian T.

    2015-01-01

    We review the development and application of nanostructured photonic crystal surfaces and a hyperspectral reflectance imaging detection instrument which, when used together, represent a new form of optical microscopy that enables label-free, quantitative, and kinetic monitoring of biomaterial interaction with substrate surfaces. Photonic Crystal Enhanced Microscopy (PCEM) has been used to detect broad classes of materials which include dielectric nanoparticles, metal plasmonic nanoparticles, biomolecular layers, and live cells. Because PCEM does not require cytotoxic stains or photobleachable fluorescent dyes, it is especially useful for monitoring the long-term interactions of cells with extracellular matrix surfaces. PCEM is only sensitive to the attachment of cell components within ~200 nm of the photonic crystal surface, which may correspond to the region of most interest for adhesion processes that involve stem cell differentiation, chemotaxis, and metastasis. PCEM has also demonstrated sufficient sensitivity for sensing nanoparticle contrast agents that are roughly the same size as protein molecules, which may enable applications in “digital” diagnostics with single molecule sensing resolution. We will review PCEM’s development history, operating principles, nanostructure design, and imaging modalities that enable tracking of optical scatterers, emitters, absorbers, and centers of dielectric permittivity. PMID:26343684

  1. Label-Free Biosensor Imaging on Photonic Crystal Surfaces.

    PubMed

    Zhuo, Yue; Cunningham, Brian T

    2015-01-01

    We review the development and application of nanostructured photonic crystal surfaces and a hyperspectral reflectance imaging detection instrument which, when used together, represent a new form of optical microscopy that enables label-free, quantitative, and kinetic monitoring of biomaterial interaction with substrate surfaces. Photonic Crystal Enhanced Microscopy (PCEM) has been used to detect broad classes of materials which include dielectric nanoparticles, metal plasmonic nanoparticles, biomolecular layers, and live cells. Because PCEM does not require cytotoxic stains or photobleachable fluorescent dyes, it is especially useful for monitoring the long-term interactions of cells with extracellular matrix surfaces. PCEM is only sensitive to the attachment of cell components within ~200 nm of the photonic crystal surface, which may correspond to the region of most interest for adhesion processes that involve stem cell differentiation, chemotaxis, and metastasis. PCEM has also demonstrated sufficient sensitivity for sensing nanoparticle contrast agents that are roughly the same size as protein molecules, which may enable applications in "digital" diagnostics with single molecule sensing resolution. We will review PCEM's development history, operating principles, nanostructure design, and imaging modalities that enable tracking of optical scatterers, emitters, absorbers, and centers of dielectric permittivity. PMID:26343684

  2. A novel assay for detecting canine parvovirus using a quartz crystal microbalance biosensor.

    PubMed

    Kim, Yong Kwan; Lim, Seong-In; Choi, Sarah; Cho, In-Soo; Park, Eun-Hye; An, Dong-Jun

    2015-07-01

    Rapid and accurate diagnosis is crucial to reduce both the shedding and clinical signs of canine parvovirus (CPV). The quartz crystal microbalance (QCM) is a new tool for measuring frequency changes associated with antigen-antibody interactions. In this study, the QCM biosensor and ProLinker™ B were used to rapidly diagnosis CPV infection. ProLinker™ B enables antibodies to be attached to a gold-coated quartz surface in a regular pattern and in the correct orientation for antigen binding. Receiver operating characteristics (ROC) curves were used to set a cut-off value using reference CPVs (two groups: one CPV-positive and one CPV-negative). The ROC curves overlapped and the point of intersection was used as the cut-off value. A QCM biosensor with a cut-off value of -205 Hz showed 95.4% (104/109) sensitivity and 98.0% (149/152) specificity when used to test 261 field fecal samples compared to PCR. In conclusion, the QCM biosensor described herein is eminently suitable for the rapid diagnosis of CPV infection with high sensitivity and specificity. Therefore, it is a promising analytical tool that will be useful for clinical diagnosis, which requires rapid and reliable analyses. PMID:25813597

  3. Design optimization of structural parameters for highly sensitive photonic crystal label-free biosensors.

    PubMed

    Ju, Jonghyun; Han, Yun-ah; Kim, Seok-min

    2013-01-01

    The effects of structural design parameters on the performance of nano-replicated photonic crystal (PC) label-free biosensors were examined by the analysis of simulated reflection spectra of PC structures. The grating pitch, duty, scaled grating height and scaled TiO2 layer thickness were selected as the design factors to optimize the PC structure. The peak wavelength value (PWV), full width at half maximum of the peak, figure of merit for the bulk and surface sensitivities, and surface/bulk sensitivity ratio were also selected as the responses to optimize the PC label-free biosensor performance. A parametric study showed that the grating pitch was the dominant factor for PWV, and that it had low interaction effects with other scaled design factors. Therefore, we can isolate the effect of grating pitch using scaled design factors. For the design of PC-label free biosensor, one should consider that: (1) the PWV can be measured by the reflection peak measurement instruments, (2) the grating pitch and duty can be manufactured using conventional lithography systems, and (3) the optimum design is less sensitive to the grating height and TiO2 layer thickness variations in the fabrication process. In this paper, we suggested a design guide for highly sensitive PC biosensor in which one select the grating pitch and duty based on the limitations of the lithography and measurement system, and conduct a multi objective optimization of the grating height and TiO2 layer thickness for maximizing performance and minimizing the influence of parameter variation. Through multi-objective optimization of a PC structure with a fixed grating height of 550 nm and a duty of 50%, we obtained a surface FOM of 66.18 RIU-1 and an S/B ratio of 34.8%, with a grating height of 117 nm and TiO2 height of 210 nm. PMID:23470487

  4. Label-free detection of glycated haemoglobin in human blood using silicon-based photonic crystal nanocavity biosensor

    NASA Astrophysics Data System (ADS)

    Olyaee, Saeed; Seifouri, Mahmood; Mohsenirad, Hamideh

    2016-07-01

    In this paper, we describe a two-dimensional photonic crystal-based biosensor that consists of a waveguide and a nanocavity with high sensitivity. A new method is employed for increasing sensitivity of the biosensor. The simulation results show that biosensor is highly sensitive to the refractive index (RI) variations due to injected biomaterials, like glycated haemoglobin, into the sensing surface. The proposed biosensor is designed for the wavelength range of 1514.4-1896.3 nm. The sensitivity and the quality factor are calculated to be 3000 and 272.43 nm/RIU, respectively. The designed structure can detect a 0.002 change in the RI via resonant wavelength shift of 0.9 nm. The band diagram and transmission spectra are computed using plane wave expansion and finite difference time domain methods.

  5. Hollow core photonic crystal fiber as a robust Raman biosensor

    NASA Astrophysics Data System (ADS)

    Khetani, Altaf; Momenpour T. Monfared, Ali; Tiwari, Vidhu S.; Anis, Hanan; Riordon, Jason; Godin, Michel

    2013-03-01

    The present work demonstrates the integration of hollow core photonic crystal fibers (HC-PCF), microfluidics, and statistical analysis for monitoring biomolecules using Raman spectroscopy. HC-PCF as a signal enhancer has been proven by many researchers. However, there have been challenges in using HC-PCF for practical applications due to limitations such as coupling, stability, evaporation, clogging, consistent filling, and reusing the same fiber. This limited the potential of HC-PCF to detect low concentrations of liquid samples, which is why HC-PCF still hasn't transcended the lab barriers. The current device is based on an H-design lay-out which uses the pressure difference between the two ends of the fiber for filling and flushing the liquid samples. This mitigated several issues related to device performance by allowing us to fill the fiber with liquid samples consistently, rapidly and reproducibly. The resulting Raman signals were significantly more stable as various concentrations of ethanol in water were sequentially introduced into the fiber. The scheme also allowed us to overcome the barrier of predicting low concentrations by applying Partial Least Square (PLS) technique which was done for the first time using HC-PCF. Thus, the present scheme paves path for the inclusion of HC-PCF in the main stream point-of-care technology.

  6. Quartz crystal microbalance biosensor for rapid detection of aerosolized microorganisms

    NASA Astrophysics Data System (ADS)

    Farka, Zdenĕk.; Kovár, David; Skládal, Petr

    2015-05-01

    Biological warfare agents (BWAs) represent the current menace of the asymmetric war. The early detection of BWAs, especially in the form of bioaerosol, is a challenging task for governments all around the world. Label-free quartz crystal microbalance (QCM) immunosensor and electrochemical immunosensor were developed and tested for rapid detection of BWA surrogate (E. coli) in the form of bioaerosol. Two immobilization strategies for the attachment of antibody were tested; the gold sensor surface was activated by cysteamine and then antibody was covalently linked either using glutaraldehyde, or the reduced antibodies were attached via Sulfo-SMCC. A portable bioaerosol chamber was constructed and used for safe manipulation with aerosolized microorganisms. The dissemination was done using a piezoelectric humidifier, distribution of bioaerosol inside the chamber was ensured using three 12-cm fans. The whole system was controlled remotely using LAN network. The disseminated microbial cells were collected and preconcentrated using the wetted-wall cyclone SASS 2300, the analysis was done using the on-line linked immunosensors. The QCM immunosensor had limit of detection 1×104 CFU·L-1 of air with analysis time 16 min, the whole experiment including dissemination and sensor surface regeneration took 40 min. In case of blank (disseminated sterile buffer), no signal change was observed. The electrochemical immunosensor was able to detect 150 CFU·L-1 of air in 20 min; also in this case, no interferences were observed. Reference measurements were done using particle counter Met One 3400 and by cultivation method on agar plates. The sensors have proved to be applicable for rapid screening of microorganisms in air.

  7. Detection of Myoglobin with an Open-Cavity-Based Label-Free Photonic Crystal Biosensor

    PubMed Central

    Zhang, Bailin; Tamez-Vela, Juan Manuel; Solis, Steven; Bustamante, Gilbert; Peterson, Ralph; Rahman, Shafiqur; Morales, Andres; Tang, Liang; Ye, Jing Yong

    2013-01-01

    The label-free detection of one of the cardiac biomarkers, myoglobin, using a photonic-crystal-based biosensor in a total-internal-reflection configuration (PC-TIR) is presented in this paper. The PC-TIR sensor possesses a unique open optical microcavity that allows for several key advantages in biomolecular assays. In contrast to a conventional closed microcavity, the open configuration allows easy functionalization of the sensing surface for rapid biomolecular binding assays. Moreover, the properties of PC structures make it easy to be designed and engineered for operating at any optical wavelength. Through fine design of the photonic crystal structure, biochemical modification of the sensor surface, and integration with a microfluidic system, we have demonstrated that the detection sensitivity of the sensor for myoglobin has reached the clinically significant concentration range, enabling potential usage of this biosensor for diagnosis of acute myocardial infarction. The real-time response of the sensor to the myoglobin binding may potentially provide point-of-care monitoring of patients and treatment effects. PMID:27006922

  8. Hydrogenated amorphous silicon nitride photonic crystals for improved-performance surface electromagnetic wave biosensors

    PubMed Central

    Sinibaldi, Alberto; Descrovi, Emiliano; Giorgis, Fabrizio; Dominici, Lorenzo; Ballarini, Mirko; Mandracci, Pietro; Danz, Norbert; Michelotti, Francesco

    2012-01-01

    We exploit the properties of surface electromagnetic waves propagating at the surface of finite one dimensional photonic crystals to improve the performance of optical biosensors with respect to the standard surface plasmon resonance approach. We demonstrate that the hydrogenated amorphous silicon nitride technology is a versatile platform for fabricating one dimensional photonic crystals with any desirable design and operating in a wide wavelength range, from the visible to the near infrared. We prepared sensors based on photonic crystals sustaining either guided modes or surface electromagnetic waves, also known as Bloch surface waves. We carried out for the first time a direct experimental comparison of their sensitivity and figure of merit with surface plasmon polaritons on metal layers, by making use of a commercial surface plasmon resonance instrument that was slightly adapted for the experiments. Our measurements demonstrate that the Bloch surface waves on silicon nitride photonic crystals outperform surface plasmon polaritons by a factor 1.3 in terms of figure of merit. PMID:23082282

  9. Biosensor architecture for enhanced disease diagnostics: lab-in-a-photonic-crystal.

    PubMed

    Feng, Shuai; Jiang, Jian-Hua; Rashid, Abdullah Al; John, Sajeev

    2016-05-30

    A conceptual lab-in-a-photonic-crystal biosensor is demonstrated that can multiplex four or more distinct disease-markers and distinguish their presence and combinations simultaneously with unique spectral fingerprints. This biosensor consists of a photonic-band-gap, multi-mode waveguide coupled to surface modes on either side, encased in a glass slide with microfluidic channels. The spectral fingerprints consist of multiple peaks in optical transmission vs. frequency that respond sensitively and uniquely in both frequency shift and nonmonotonic change of peak transmittance levels to various analyte bindings. This special property enables complete, logical determination of twelve different combinations of four distinct disease-markers through one scan of the transmission spectrum. The results reveal unique phenomena such as switching between the strong-coupling and weak-coupling combinations of surface states by analyte binding at different locations along the central waveguide. The unconventional transmission spectra are explained using a Landauer-Büttiker, multiple-scattering, transmission theory that reproduces the main features of the exact finite-difference-time-domain simulation. PMID:27410136

  10. Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

    SciTech Connect

    Tyagi, Mukta; Agrawal, V. V.; Chandran, Achu; Joshi, Tilak; Prakash, Jai; Biradar, A. M.

    2014-04-14

    A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

  11. Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

    NASA Astrophysics Data System (ADS)

    Tyagi, Mukta; Chandran, Achu; Joshi, Tilak; Prakash, Jai; Agrawal, V. V.; Biradar, A. M.

    2014-04-01

    A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

  12. Surface plasmon resonance biosensor based on large size square-lattice photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Bing, Pibin; Li, Zhongyang; Yuan, Sheng; Yao, Jianquan; Lu, Ying

    2016-04-01

    A surface plasmon resonance biosensor based on large size square-lattice photonic crystal fiber has been designed and simulated by finite element method. The square-lattice airholes are first coated with a calcium fluoride layer to provide mode confinement, then a nanoscale gold layer is deposited to excite the plasmon mode, and finally, the sample is infiltrated into the holes. The numerical results reveal that the resonance properties are easily affected by many parameters. The refractive index resolution of corresponding sensor can reach 4.3 × 10-6 RIU when the optimum parameters are set as the radius of curvature of the airhole r = 2 μm, the thickness of the core struts c = 200 nm, the auxiliary dielectric layer s = 1 μm, and the gold film d = 40 nm. In addition, the effective area and nonlinear coefficient are calculated.

  13. Handheld imaging photonic crystal biosensor for multiplexed, label-free protein detection

    PubMed Central

    Jahns, Sabrina; Bräu, Marion; Meyer, Björn-Ole; Karrock, Torben; Gutekunst, Sören B.; Blohm, Lars; Selhuber-Unkel, Christine; Buhmann, Raymund; Nazirizadeh, Yousef; Gerken, Martina

    2015-01-01

    We present a handheld biosensor system for the label-free and specific multiplexed detection of several biomarkers employing a spectrometer-free imaging measurement system. A photonic crystal surface functionalized with multiple specific ligands forms the optical transducer. The photonic crystal slab is fabricated on a glass substrate by replicating a periodic grating master stamp with a period of 370 nm into a photoresist via nanoimprint lithography and deposition of a 70-nm titanium dioxide layer. Capture molecules are coupled covalently and drop-wise to the photonic crystal surface. With a simple camera and imaging optics the surface-normal transmission is detected. In the transmission spectrum guided-mode resonances are observed that shift due to protein binding. This shift is observed as an intensity change in the green color channel of the camera. Non-functionalized image sections are used for continuous elimination of background drift. In a first experiment we demonstrate the specific and time-resolved detection of 90.0 nm CD40 ligand antibody, 90.0 nM EGF antibody, and 500 nM streptavidin in parallel on one sensor chip. In a second experiment, aptamers with two different spacer lengths are used as receptor. The binding kinetics with association and dissociation of 250 nM thrombin and regeneration of the sensor surface with acidic tris-HCl-buffer (pH 5.0) is presented for two measurement cycles. PMID:26504624

  14. Acetylcholinesterase liquid crystal biosensor based on modulated growth of gold nanoparticles for amplified detection of acetylcholine and inhibitor.

    PubMed

    Liao, Shuzhen; Qiao, Yanan; Han, Wenting; Xie, Zhaoxia; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2012-01-01

    A novel acetylcholinesterase (AChE) liquid crystal (LC) biosensor based on enzymatic growth of gold nanoparticles (Au NPs) has been developed for amplified detection of acetylcholine (ACh) and AChE inhibitor. In this method, AChE mediates the hydrolysis of acetylthiocholine (ATCl) to form thiocholine, and the latter further reduces AuCl(4)(-) to Au NPs without Au nanoseeds. This process, termed biometallization, leads to a great enhancement in the optical signal of the LC biosensor due to the large size of Au NPs, which can greatly disrupt the orientational arrangement of LCs. On the other hand, the hydrolysis of ATCl is inhibited in the presence of ACh or organophosphate pesticides (OPs, a AChE inhibitor), which will decrease the catalytic growth of Au NPs and, as a result, reduce the orientational response of LCs. On the basis of such an inhibition mechanism, the AChE LC biosensor can be used as an effective way to realize the detection of ACh and AChE inhibitors. The results showed that the AChE LC biosensor was highly sensitive to ACh with a detection limit of 15 μmol/L and OPs with a detection limit of 0.3 nmol/L. This study provides a simple and sensitive AChE LC biosensing approach and offers effective signal enhanced strategies for the development of enzyme LC biosensors. PMID:22148672

  15. Edge-driven microplate kinematics

    USGS Publications Warehouse

    Schouten, Hans; Klitgord, Kim D.; Gallo, David G.

    1993-01-01

    It is known from plate tectonic reconstructions that oceanic microplates undergo rapid rotation about a vertical axis and that the instantaneous rotation axes describing the microplate's motion relative to the bounding major plates are frequently located close to its margins with those plates, close to the tips of propagating rifts. We propose a class of edge-driven block models to illustrate how slip across the microplate margins, block rotation, and propagation of rifting may be related to the relative motion of the plates on either side. An important feature of these edge-driven models is that the instantaneous rotation axes are always located on the margins between block and two bounding plates. According to those models the pseudofaults or traces of disrupted seafloor resulting from the propagation of rifting between microplate and major plates may be used independently to approximately trace the continuous kinematic evolution of the microplate back in time. Pseudofault geometries and matching rotations of the Easter microplate show that for most of its 5 m.y. history, block rotation could be driven by the drag of the Nazca and Pacific plates on the microplate's edges rather than by a shear flow of mantle underneath.

  16. User-friendly, miniature biosensor flow cell for fragile high fundamental frequency quartz crystal resonators.

    PubMed

    Sagmeister, Brigitte P; Graz, Ingrid M; Schwödiauer, Reinhard; Gruber, Hermann; Bauer, Siegfried

    2009-04-15

    For the application of high fundamental frequency (HFF) quartz crystal resonators as ultra sensitive acoustic biosensors, a tailor-made quartz crystal microbalance (QCM) flow cell has been fabricated and tested. The cell permits an equally fast and easy installation and replacement of small and fragile HFF sensors. Usability and simple fabrication are two central features of the HFF-QCM flow cell. Mechanical, thermal, electrical and chemical requirements are considered. The design of the cell combines these, partially contradictory, requirements within a simple device. Central design concepts are discussed and a brief description of the fabrication, with a special focus on the preparation of crucial parts, is provided. For test measurements, the cell was equipped with a standard 50 MHz HFF resonator which had been surface-functionalised with a self-assembled monolayer of 1-octadecanethiol. The reliable performance is demonstrated with two types of experiments: the real time monitoring of phospholipid monolayer formation and its removal with detergent, as well as step-wise growth of a protein multilayer system by an alternating immobilisation of streptavidin and biotinylated immunoglobulin G. PMID:19231152

  17. Recognition of apoptotic cells by viable cells is specific, ubiquitous, and species independent: analysis using photonic crystal biosensors

    PubMed Central

    Pattabiraman, Goutham; Lidstone, Erich A.; Palasiewicz, Karol; Cunningham, Brian T.; Ucker, David S.

    2014-01-01

    Apoptotic recognition is innate and linked to a profound immune regulation (innate apoptotic immunity [IAI]) involving anti-inflammatory and immunosuppressive responses. Many of the molecular and mechanistic details of this response remain elusive. Although immune outcomes can be quantified readily, the initial specific recognition events have been difficult to assess. We developed a sensitive, real-time method to detect the recognition of apoptotic cells by viable adherent responder cells, using a photonic crystal biosensor approach. The method relies on characteristic spectral shifts resulting from the specific recognition and dose-dependent interaction of adherent responder cells with nonadherent apoptotic targets. Of note, the biosensor provides a readout of early recognition-specific events in responder cells that occur distal to the biosensor surface. We find that innate apoptotic cell recognition occurs in a strikingly species-independent manner, consistent with our previous work and inferences drawn from indirect assays. Our studies indicate obligate cytoskeletal involvement, although apoptotic cell phagocytosis is not involved. Because it is a direct, objective, and quantitative readout of recognition exclusively, this biosensor approach affords a methodology with which to dissect the early recognition events associated with IAI and immunosuppression. PMID:24694594

  18. Improving the binding efficiency of quartz crystal microbalance biosensors by applying the electrothermal effect

    PubMed Central

    Huang, Yao-Hung; Chang, Jeng-Shian; Chao, Sheng D.; Wu, Kuang-Chong; Huang, Long-Sun

    2014-01-01

    A quartz crystal microbalance (QCM) serving as a biosensor to detect the target biomolecules (analytes) often suffers from the time consuming process, especially in the case of diffusion-limited reaction. In this experimental work, we modify the reaction chamber of a conventional QCM by integrating into the multi-microelectrodes to produce electrothermal vortex flow which can efficiently drive the analytes moving toward the sensor surface, where the analytes were captured by the immobilized ligands. The microelectrodes are placed on the top surface of the chamber opposite to the sensor, which is located on the bottom of the chamber. Besides, the height of reaction chamber is reduced to assure that the suspended analytes in the fluid can be effectively drived to the sensor surface by induced electrothermal vortex flow, and also the sample costs are saved. A series of frequency shift measurements associated with the adding mass due to the specific binding of the analytes in the fluid flow and the immobilized ligands on the QCM sensor surface are performed with or without applying electrothermal effect (ETE). The experimental results show that electrothermal vortex flow does effectively accelerate the specific binding and make the frequency shift measurement more sensible. In addition, the images of the binding surfaces of the sensors with or without applying electrothermal effect are taken through the scanning electron microscopy. By comparing the images, it also clearly indicates that ETE does raise the specific binding of the analytes and ligands and efficiently improves the performance of the QCM sensor. PMID:25538808

  19. Label-free Detection of Cardiac Troponin I with a Photonic Crystal Biosensor

    PubMed Central

    Zhang, Bailin; Morales, Andres W.; Peterson, Ralph; Tang, Liang; Ye, Jing Yong

    2014-01-01

    A biosensor has been developed with a photonic crystal structure used in a total-internal-reflection (PC-TIR) configuration for label-free detection of a cardiac biomarker: Troponin I (cTnI). In contrast to a conventional optical microcavity that has a closed structure with its cavity layer sandwiched between two high-reflection surfaces, the PC-TIR configuration creates a unique open microcavity, which allows its cavity layer (sensing layer) to be easily functionalized and directly exposed to analyte molecules for bioassays. In this study, a PC-TIR sensor has been used for the label-free measurements of cardiac biomarkers by monitoring the changes in the resonant condition of the cavity due to biomolecular binding processes. Antibodies against cTnI are immobilized on the sensor surface for specific detection of cTnI with a wide range of concentrations. Detection limit of cTnI with a concentration as low as 0.1 ng mL−1 has been achieved. PMID:24632136

  20. Highly sensitive color-indicating and quantitative biosensor based on cholesteric liquid crystal

    PubMed Central

    Hsiao, Yu-Cheng; Sung, Yu-Chien; Lee, Mon-Juan; Lee, Wei

    2015-01-01

    Liquid crystal (LC)-based biosensors employ highly sensitive interfaces between the alignment layers and LCs to detect biomolecules and their interactions. Present techniques based on optical texture observation of the homeotropic-to-planar response of nematic LCs are limited by their quantitative reproducibility of results, indicating that both the accuracy and reliability of LC-based detection require further improvements. Here we show that cholesteric LC (CLC) can be used as a novel sensing element in the design of an alternative LC-based biosensing device. The chirality of the vertically anchored (VA) CLC was exploited in the detection of bovine serum albumin (BSA), a protein standard commonly used in protein quantitation. The color appearance and the corresponding transmission spectrum of the cholesteric phase changed with the concentration of BSA, by which a detection limit of 1 fg/ml was observed. The optical response of the VA CLC interface offers a simple and inexpensive platform for highly sensitive and naked-eye color-indicating detection of biomolecules, and, thus, may facilitate the development of point-of-care devices for the detection of disease-related biomarkers. PMID:26713215

  1. Highly-sensitive liquid crystal biosensor based on DNA dendrimers-mediated optical reorientation.

    PubMed

    Tan, Hui; Li, Xia; Liao, Shuzhen; Yu, Ruqin; Wu, Zhaoyang

    2014-12-15

    A novel highly-sensitive liquid crystal (LC) biosensing approach based on target-triggering DNA dendrimers was developed for the detection of p53 mutation gene segment at the LC-aqueous interface. In this study, the mutant-type p53 gene segment was the target to trigger the formation of DNA dendrimers from hairpin DNA probes by hybridization chain reaction, and the latter as a 'signal enhancement element' further induced the LC reorientation from tilted to homeotropic alignment, resulting in a corresponding optical changes of LC biosensors from birefringent to honeycombed textures or dark framework. The distinct optical reorientational appearances can serve as a characteristic signal to distinguish target concentrations ranging from 0.08 nM to 8 nM. Moreover, these optical phenomena suggest that the LC reorientation is related to the electric-dipole coupling between the adsorbed DNA and LC molecules, the conformational constraints of DNA and the internal electric field induction upon hybridization. This label-free LC biosensing strategy can open up a new platform for the sensitive detection of specific DNA sequences and enrich the application scope of an LC biosensing technique. PMID:24984288

  2. Highly sensitive color-indicating and quantitative biosensor based on cholesteric liquid crystal.

    PubMed

    Hsiao, Yu-Cheng; Sung, Yu-Chien; Lee, Mon-Juan; Lee, Wei

    2015-12-01

    Liquid crystal (LC)-based biosensors employ highly sensitive interfaces between the alignment layers and LCs to detect biomolecules and their interactions. Present techniques based on optical texture observation of the homeotropic-to-planar response of nematic LCs are limited by their quantitative reproducibility of results, indicating that both the accuracy and reliability of LC-based detection require further improvements. Here we show that cholesteric LC (CLC) can be used as a novel sensing element in the design of an alternative LC-based biosensing device. The chirality of the vertically anchored (VA) CLC was exploited in the detection of bovine serum albumin (BSA), a protein standard commonly used in protein quantitation. The color appearance and the corresponding transmission spectrum of the cholesteric phase changed with the concentration of BSA, by which a detection limit of 1 fg/ml was observed. The optical response of the VA CLC interface offers a simple and inexpensive platform for highly sensitive and naked-eye color-indicating detection of biomolecules, and, thus, may facilitate the development of point-of-care devices for the detection of disease-related biomarkers. PMID:26713215

  3. Real-time multianalyte biosensors based on interference-free multichannel monolithic quartz crystal microbalance.

    PubMed

    Jaruwongrungsee, Kata; Waiwijit, Uraiwan; Wisitsoraat, Anurat; Sangworasil, Manas; Pintavirooj, Chuchart; Tuantranont, Adisorn

    2015-05-15

    In this work, we design, fabricate and characterize a new interference-free multichannel monolithic quartz crystal microbalance (MQCM) platform for bio-sensing applications. Firstly, interference due to thickness-shear vibration mode coupling between channels in MQCM array is effectively suppressed by interposing a polydimethylsiloxane wall between adjacent QCM electrodes on a quartz substrate to form inverted-mesa-like structure. In addition, the electrical coupling due to the electrical impedance of solution is diminished by extending the flow path between them with an extended-design flow channel. The electrical testing results show that individual QCM signal is unaffected by those of adjacent channels under liquid loading, signifying the achievement of interference-free MQCM. The MQCM is applied for multi-analyte biosensing of IgG and HSA. The anti-IgG and anti-HSA are separately immobilized on two adjacent QCM electrodes, which are subsequently blocked with BSA to avoid unspecific binding. The MQCM biosensors are tested with single- and double-analyte solutions under continuous flow of buffer. The IgG and HSA QCM sensors only show frequency shift responses to their corresponding analytes and there are very small cross frequency shifts due to remnant unspecific binding. Moreover, MQCM sensors show approximately linear frequency shift response with analyte concentration. Therefore, the developed MQCM platform is promising for real-time interference-free label-free detection and quantification of multiple bio-analytes. PMID:25307623

  4. Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions.

    PubMed

    Yang, Shengyuan; Wu, Chao; Tan, Hui; Wu, Yan; Liao, Shuzhen; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2013-01-01

    In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors. PMID:23214408

  5. Liquid crystal-based glucose biosensor functionalized with mixed PAA and QP4VP brushes.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2015-06-15

    4-Cyano-4'-pentylbiphenyl (5CB) in a transmission electron microscopy (TEM) grid was developed for glucose detection by coating with a monolayer of mixed polymer brushes using poly(acrylicacid-b-4-cynobiphenyl-4'-oxyundecylacrylate) (PAA-b-LCP) and quaternized poly(4-vinylpyridine-b-4-cynobiphenyl-4'-oxyundecylacrylate) (QP4VP-b-LCP) (LCP stands for liquid crystal polymer) at the 5CB/aqueous interface. The resultant 5CB in TEM grid was functionalized with the PAA and QP4VP brushes, which were strongly anchored by the LCP block. The PAA brush rendered the 5CB/aqueous interface pH-responsive and the QP4VP brush immobilized glucose oxidase (GOx) through electrostatic interactions without the aid of coupling agents. The glucose was detected through a homeotropic-to-planar orientational transition of the 5CB observed through a polarized optical microscope (POM) under crossed polarizers. The optimum immobilization with a 0.78 µM GOx solution on the dual-brush-coated TEM grid enabled glucose detection at concentrations higher than 0.5 mM with response times shorter than 180 s. This TEM grid glucose sensor provided a linear response of birefringence of the 5CB to glucose concentrations ranging from 0.5 to 11 mM with a Michaelis-Menten constant (Km) of 1.67 mM. This new and sensitive glucose biosensor has the advantages of low production cost, simple enzyme immobilization, high enzyme sensitivity and stability, and easy detection with POM, and may be useful for prescreening the glucose level in the human body. PMID:25617751

  6. Development of optical biosensor based on photonic crystal made of TiO2 using liquid phase deposition

    NASA Astrophysics Data System (ADS)

    Aono, Keigo; Aki, Shoma; Sueyoshi, Kenji; Hisamoto, Hideaki; Endo, Tatsuro

    2016-08-01

    We fabricated a titanium dioxide (TiO2)-based photonic crystal (PhC) using liquid phase deposition (LPD) to develop highly sensitive optical biosensors. The optical characteristics of the PhCs in the visible region were sensitive to the change in the refractive index of the surrounding medium due to an antigen–antibody reaction; thus, applications using the optical biosensor are expected to be highly sensitive. However, a base material with a high refractive index is indispensable for the fabrication of the PhC. Here, TiO2, which has optical transparency in the visible region, was selected as the high refractive index base material. The present LPD method allowed fabrication using low-cost apparatus. Furthermore, the mild conditions of the LPD method led to formation of TiO2-based PhC with fewer crack structures. Finally, the anti-neuron-specific enolase antibody was immobilized onto the TiO2-based PhC surface, and 1–1000 ng/mL of the neuron-specific enolase antigen was successfully detected.

  7. Glucose biosensor based on GOx/HRP bienzyme at liquid-crystal/aqueous interface.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2015-11-01

    Glucose oxidase (GOx) and horseradish peroxidase (HRP) were co-immobilized to the polyacrylicacid block of a poly(acrylicacid-b-4-cyanobiphenyl-4'-undecylacrylate) (PAA-b-LCP) copolymer in water. PAA-b-LCP was strongly anchored by the LCP block in 4-cyano-4'-pentylbiphenyl (5CB) which was contained in a transmission electron microscope (TEM) grid for glucose detection. The optimal conditions for the performance of the TEM grid glucose biosensor were studied in terms of the activity and stability of the immobilized enzymes. Glucose in water was detected by the 5CB changing from a planar to a homeotropic orientation, as observed through a polarized optical microscope. The TEM biosensor detected glucose concentrations at ⩾0.02 mM, with an optimal GOx/HRP molar ratio of 3/1. This glucose biosensor has characteristics of enzyme sensitivity and stability, reusability, the ease and selective glucose detection which may provide a new way of detecting glucose. PMID:26196711

  8. Development of a Mass Sensitive Quartz Crystal Microbalance (QCM)-Based DNA Biosensor Using a 50 MHz Electronic Oscillator Circuit

    PubMed Central

    García-Martinez, Gonzalo; Bustabad, Enrique Alonso; Perrot, Hubert; Gabrielli, Claude; Bucur, Bogdan; Lazerges, Mathieu; Rose, Daniel; Rodriguez-Pardo, Loreto; Fariña, Jose; Compère, Chantal; Vives, Antonio Arnau

    2011-01-01

    This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm2 in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected. PMID:22164037

  9. A biosensor of high-density lipoprotein of human serum on a liquid crystal and polymer composite film

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsin; Chang, Kai-Han; Chu, Wei-Lin; Tsou, Yu-Shih; Wu, Li-Ching; Li, Chien-Feng

    2013-10-01

    A biosensor for the concentration of high-density lipoprotein (HDL) in human serum on a liquid crystal and polymer composite film (LCPCF) is demonstrated. The sensing mechanism is based on a polar-polar interaction between orientation of LC directors and HDL in human serum. The concentration of polar HDL in human serum affects the orientations of LC directors at the interface between LCPCF and the human serum. In addition, the surface free energy of LCPCF changes with the applied voltage due to the electrically tunable orientations of LC directors anchored among the polymer grains of LCPCF. As a result, the droplet motion of human serum on LCPCF under applied voltages can sense the concentration of HDL in human serum.

  10. Development of a mass sensitive quartz crystal microbalance (QCM)-based DNA biosensor using a 50 MHz electronic oscillator circuit.

    PubMed

    García-Martinez, Gonzalo; Bustabad, Enrique Alonso; Perrot, Hubert; Gabrielli, Claude; Bucur, Bogdan; Lazerges, Mathieu; Rose, Daniel; Rodriguez-Pardo, Loreto; Fariña, Jose; Compère, Chantal; Vives, Antonio Arnau

    2011-01-01

    This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm(2) in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected. PMID:22164037

  11. A comparative study of the cytoskeleton binding drugs nocodazole and taxol with a mammalian cell quartz crystal microbalance biosensor: different dynamic responses and energy dissipation effects.

    PubMed

    Marx, Kenneth A; Zhou, Tiean; Montrone, Anne; McIntosh, Donna; Braunhut, Susan J

    2007-02-01

    The quartz crystal microbalance (QCM) was used to create piezoelectric whole-cell biosensors utilizing either living endothelial cells (ECs) or the metastatic human mammary cancer cell line MDA-MB-231 adhering to the gold QCM surface under in vitro growth conditions. We utilized the whole-cell QCM biosensors for the detection of the effects of varying concentrations of the microtubule binding drugs taxol and nocodazole by measuring changes in the QCM steady state frequency (Deltaf) and motional resistance (DeltaR), shift values. Using 0.11-50 microM nocodazole, we observed the Deltaf shift values of the biosensors, consisting of 20,000 ECs, to decrease significantly in magnitude (nearly 100%) to a limiting value, in a dose-dependent fashion, over a 5- to 6-h incubation period following drug addition. This effect is consistent with nocodazole's known disruption of intracellular microtubules. On the other hand, 10 microM taxol caused little alteration in Deltaf over the same time period, consistent with its microtubule hyperstabilization effect. When the EC QCM biosensor Deltaf shift values were normalized by the number of ECs found firmly attached to the QCM surface via trypsin removal and electronic counting, the dose curve was shifted to lower nocodazole concentrations, resulting in a more sensitive drug biosensor. The kinetics of the Deltaf decrease with increasing nocodazole concentrations measured by the EC QCM biosensor was found to be similar at all drug concentrations and was well fit by a single first-order exponential decay equation. For all nocodazole doses, t(0.5) was invariant, averaging t(0.5)=0.83+/-0.14 h. These data demonstrate that a single dynamic sensing system within the cell, the microtubules, is disrupted by the addition of nocodazole and this process is sensed by the cell QCM biosensor. This interpretation of the data was confirmed by a fluorescence light microscopy investigation of ECs undergoing treatment with increasing nocodazole doses

  12. A semistatic microplate-based phytotoxicity test

    SciTech Connect

    Radetski, C.M.; Ferard, J.F. . Centre des Sciences de l'Environnement); Blaise, C. )

    1995-02-01

    A novel phytotoxicity test is described herein that employs a microplate equipped with membrane-bottomed wells. This MultiScreen[trademark] (Millipore Corp., Bedford, MA) microplate allows performance of a semistatic algal test, in which test medium is renewed periodically. With such a design, the algal test becomes comparable to other short-term tests used to evaluate chronic toxicity of chemicals and effluents. The EC50s obtained for Cu[sup 2+], Cd[sup 2+], Cr[sup 6+], atrazine, and one leachate sample (municipal sludge incinerator residue) with static and semistatic algal microplate tests were compared in this study. The semistatic microplate test revealed greater sensitivity than did the static microplate test.

  13. QUARTZ CRYSTAL MICROBALANCE BIOSENSOR FOR MEASUREMENT OF 2,4-D IN WATER

    EPA Science Inventory

    Due to proportional relationship between vibrational frequency and surface mass, the quartz crystal microbalance (QCM) has been used to detect the accumulation of small quantities of chemical and biological compounds on electrode-covered quartz crystals. lassically, these devices...

  14. Disposable micro-fluidic biosensor array for online parallelized cell adhesion kinetics analysis on quartz crystal resonators

    NASA Astrophysics Data System (ADS)

    Cama, G.; Jacobs, T.; Dimaki, M. I.; Svendsen, W. E.; Hauptmann, P.; Naumann, M.

    2010-08-01

    In this contribution we present a new disposable micro-fluidic biosensor array for the online analysis of adherent Madin Darby canine kidney (MDCK-II) cells on quartz crystal resonators (QCRs). The device was conceived for the parallel cultivation of cells providing the same experimental conditions among all the sensors of the array. As well, dedicated sensor interface electronics were developed and optimized for fast spectra acquisition of all 16 QCRs with a miniaturized impedance analyzer. This allowed performing cell cultivation experiments for the observation of fast cellular reaction kinetics with focus on the comparison of the resulting sensor signals influenced by different cell distributions on the sensor surface. To prove the assumption of equal flow circulation within the symmetric micro-channel network and support the hypothesis of identical cultivation conditions for the cells living above the sensors, the influence of fabrication tolerances on the flow regime has been simulated. As well, the shear stress on the adherent cell layer due to the flowing media was characterized. Injection molding technology was chosen for the cheap mass production of disposable devices. Furthermore, the injection molding process was simulated in order to optimize the mold geometry and minimize the shrinkage and the warpage of the parts. MDCK-II cells were cultivated in the biosensor array. Parallel cultivation of cells on the gold surface of the QCRs led to first observations of the impact of the cell distribution on the sensor signals during cell cultivation. Indeed, the initial cell distribution revealed a significant influence on the changes in the measured acoustic load on the QCRs suggesting dissimilar cell migrations as well as proliferation kinetics of a non-confluent MDCK-II cell layer.

  15. Microplate Assay for Colletotrichum Spore Production

    PubMed Central

    Slade, S. J.; Harris, R. F.; Smith, C. S.; Andrews, J. H.; Nordheim, E. V.

    1987-01-01

    A simple microplate method was devised to assay spore production by Colletotrichum gloeosporioides by growing the fungus on 1 ml of solid media in the wells of tissue culture plates. Growth and sporulation on microplates were compared at days 4 and 8 with growth and sporulation in 100-ml liquid batch cultures that involved 11 common media. Spore production per unit volume of medium was the same for solid and liquid forms of the media. Qualitative assessment of mycelial growth measured on microplates agreed with that of growth measured in liquid cultures. The microplate assay indicated that V8 juice was the best medium and that an organic content of about 6 mg/ml was optimal for high sporulation and low mycelium production. The assay provides a convenient, rapid, and inexpensive means of screening media for the production of fungal conidia in large numbers, to be used, for example, in biological control programs. PMID:16347310

  16. Fabrication of Refractive Index Tunable Polydimethylsiloxane Photonic Crystal for Biosensor Application

    NASA Astrophysics Data System (ADS)

    Raman, Karthik; Murthy, T. R. Srinivasa; Hegde, G. M.

    Photonic crystal based nanostructures are expected to play a significant role in next generation nanophotonic devices. Recent developments in two-dimensional (2D) photonic crystal based devices have created widespread interest as such planar photonic structures are compatible with conventional microelectronic and photonic devices. Various optical components such as waveguides, resonators, modulators and demultiplexers have been designed and fabricated based on 2D photonic crystal geometry. This paper presents the fabrication of refractive index tunable Polydimethylsiloxane (PDMS) polymer based photonic crystals. The advantages of using PDMS are mainly its chemical stability, bio-compatibility and the stack reduces sidewall roughness scattering. The PDMS structure with square lattice was fabricated by using silicon substrate patterned with SU8-2002 resist. The 600 nm period grating of PDMS is then fabricated using Nano-imprinting. In addition, the refractive index of PDMS is modified using certain additive materials. The resulting photonic crystals are suitable for application in photonic integrated circuits and biological applications such as filters, cavities or microlaser waveguides.

  17. Preparation of QP4VP-b-LCP liquid crystal block copolymer and its application as a biosensor.

    PubMed

    Omer, Muhammad; Park, Soo-Young

    2014-09-01

    The interface between nematic liquid crystal, 4-cyano-4'-pentylbiphenyl (5CB), and water in a transmission electron microscopy (TEM) grid cell coated with QP4VP-b-LCP (quaternized poly(4-vinylpyridine) (QP4VP) and poly(4-cyanobiphenyl-4'-oxyundecylacrylate) (LCP)) was examined for protein and DNA detection. QP4VP-b-LCP was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Quaternization of P4VP with iodomethane (CH3I) made it a strong cationic polyelectrolyte and allowed QP4VP-b-LCP to form complexes with oppositely charged biological species. Several proteins, such as bovine serum albumin (BSA), hemoglobin (Hb), α chymotrypsinogen-A (ChTg), and lysozyme (LYZ), were tested for nonspecific protein detection. By injecting the protein solutions into the TEM grid cell, the initial homeotropic orientation of the TEM grid cell changed to a planar orientation above their isoelectric points (PIs) due to electrostatic interactions between QP4VP (+charge) and proteins (-charge), which did not occur below the PIs of the tested proteins. Their minimum concentrations at which the homeotropic to planar configurational change (H-P change) occurred were 0.01, 0.02, 0.03, and 0.04 wt.% for BSA, ChTg, Hb, and LYZ, respectively. One of the strong anionic polyelectrolytes, deoxyribonucleic acid (DNA) (due to the phosphate deoxyribose backbone) was also tested. A H-P change was observed with as little as 0.0013 wt.% salmon sperm DNA regardless of the pH of the cell. A H-P change occurred in 5CB and was observed by polarized optical microscopy. This simple and inexpensive setup for nonspecific biomaterial detection provides the basic idea for developing effective selective biosensors by introducing specific binding groups, such as the aptamer and antibody. PMID:24980600

  18. Optical biosensors

    PubMed Central

    Damborský, Pavel; Švitel, Juraj

    2016-01-01

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. PMID:27365039

  19. Optical biosensors.

    PubMed

    Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

    2016-06-30

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. PMID:27365039

  20. Liquid Crystal Droplet-Embedded Biopolymer Hydrogel Sheets for Biosensor Applications.

    PubMed

    Deng, Jinan; Liang, Wenlang; Fang, Jiyu

    2016-02-17

    The development of simple, portable, and low-cost biosensing platforms is of great interest in the clinical diagnosis of disease. Here, we report liquid crystal (LC) droplet-embedded chitosan (CHI) hydrogel films formed by the Ag(+) ion-triggered fast gelation of the CHI/surfactant complex-stabilized LC emulsion which is cast on substrates. The small sheets cut from the LC droplet-embedded hydrogel films combine the advantages of both hydrogels and LC droplets, offering a portable and label-free sensing platform for the real-time detection of bile acids in a small amount of solution. We find that the response time and detection limit of LC droplet-embedded hydrogel sheets for bile acids depend on their chemical structures. PMID:26808341

  1. An Integrative Biosensor Based on Contra-Directional Coupling Two-dimensional Photonic Crystal Waveguides

    NASA Astrophysics Data System (ADS)

    Mao, Xiao-Yu; Yao, Di-Bi; Zhao, Ling-Yun; Huang, Yi-Dong; Zhang, Wei; Peng, Jiang-De

    2008-01-01

    We propose an integrative biochemical sensor utilizing the dip in the transmission spectrum of a normal single-line defect photonic crystal (PC) waveguide, which has a contra-directional coupling with another PC waveguide. When the air holes in the PC slab are filled with a liquid analyte with different refractive indices, the dip has a wavelength shift By detecting the output power variation at a certain fixed wavelength, a sensitivity of 1.2 × 10-4 is feasible. This structure is easy for integration due to its plane waveguide structure and omissible pump source. In addition, high signal to noise ratio can be expected because signal transmits via a normal single-line defect PC waveguide instead of the PC hole area or analyte.

  2. Utilizing a high fundamental frequency quartz crystal resonator as a biosensor in a digital microfluidic platform.

    PubMed

    Lederer, Thomas; Stehrer, Brigitte P; Bauer, Siegfried; Jakoby, Bernhard; Hilber, Wolfgang

    2011-12-01

    We demonstrate the operation of a digital microfluidic lab-on-a-chip system utilizing Electro Wetting on Dielectrics (EWOD) as the actuation principle and a High Fundamental Frequency (HFF; 50 MHz) quartz crystal microbalance (QCM) resonator as a mass-sensitive sensor. In a first experiment we have tested the reversible formation of a phosphor-lipid monolayer of phospholipid vesicles out of an aqueous buffer suspension onto a bio-functionalized integrated QCM sensor. A binding of bio-molecules results in an altered mass load of the resonant sensor and a shift of the resonance frequency can be measured. In the second part of the experiment, the formation of a protein multilayer composed of the biomolecule streptavidin and biotinylated immunoglobulin G was monitored. Additionally, the macroscopic contact angle was optically measured in order to verify the bio-specific binding and to test the implications onto the balance of the surface tensions. Using these sample applications, we were able to demonstrate and to verify the feasibility of integrating a mass-sensitive QCM sensor into a digital microfluidic chip. PMID:22241942

  3. Biosensors for hepatitis B virus detection.

    PubMed

    Yao, Chun-Yan; Fu, Wei-Ling

    2014-09-21

    A biosensor is an analytical device used for the detection of analytes, which combines a biological component with a physicochemical detector. Recently, an increasing number of biosensors have been used in clinical research, for example, the blood glucose biosensor. This review focuses on the current state of biosensor research with respect to efficient, specific and rapid detection of hepatitis B virus (HBV). The biosensors developed based on different techniques, including optical methods (e.g., surface plasmon resonance), acoustic wave technologies (e.g., quartz crystal microbalance), electrochemistry (amperometry, voltammetry and impedance) and novel nanotechnology, are also discussed. PMID:25253948

  4. Architecture of the Northwest Andean Microplates

    NASA Astrophysics Data System (ADS)

    Potts, L. V.; Hernandez, O.; von Frese, R. R.; Schmidt, M.

    2005-05-01

    Recently revised models on global plate boundary zones show that the North Andes microplate includes a wide distribution of seismicity, volcanic events, active faulting and extreme topography. The current description of the north Andean microplate boundaries is interpreted from a variety of geological and geophysical models including volcanism and seismicity with variable confidence levels. The poorly understood complex structure and geometry of plate boundaries limits the ability of current physical models to predict neotectonic and other effects including intra-plate lithospheric stresses and strain. Together with local surface gravity and topography data, a variety of available space geodetic sensors have substantially improved the modeling of the lithosphere for analyzing subsurface mass dynamics. They include the GPS-derived 3-D crustal velocities, high resolution (90-m) topography, seismic surveys and high resolution gravity models derived from integrated satellite (e.g., CHAMP and GRACE, 200-km resolution) and terrestrial observations (up to ~5 km resolution). Spherical wavelets is a modern tool for a multi-resolution representation of spatially heterogenously distributed gravity (consistent with the generalized boundary value problem) and for topography datasets with the distinct ability to enhance localized signals. Analysis of multi-resolution gravity and topography models combined with GPS velocities provide a unique opportunity to characterize the structure, isostatic conditions, mass dynamics, and intra-plate deformations of the North Andes microplate.

  5. Enhanced sandwich immunoassay using antibody-functionalized magnetic iron-oxide nanoparticles for extraction and detection of soluble transferrin receptor on a photonic crystal biosensor.

    PubMed

    Peterson, Ross D; Chen, Weili; Cunningham, Brian T; Andrade, Juan E

    2015-12-15

    Iron deficiency anemia (IDA) has detrimental effects on individuals and societies worldwide. A standard sandwich assay (SA) for the detection of soluble transferrin receptor (sTfR), a biomarker of IDA, on a photonic crystal (PC) biosensor was established, but it was susceptible to non-specific signals from complex matrixes. In this study, iron-oxide nanoparticles (fAb-IONs) were used as magnetic immuno-probes to bind sTfR and minimize non-specific signals, while enhancing detection on the PC biosensor. This inverse sandwich assay (IA) method completely bound sTfR with low variability (<4% RSD) in buffer and allowed for its accurate and precise detection in sera (Liquichek™ control sera) on the PC biosensor using two certified ELISAs as reference methods. A linear dose-response curve was elicited at the fAb-IONs concentration in which the theoretical binding ratio (sTfR:fAb-IONs) was calculated to be <1 on the IA. The LoDs for sTfR in the SA and IA were similar (P>0.05) at 14 and 21 μg/mL, respectively. The inherent imprecision of the IA and reference ELISAs was σ(δ)=0.45 µg/mL and the mean biases for Liquichek™ 1, 2 and 3 were 0.18, 0.19 and -0.04 µg/mL, respectively. Whereas the inherent imprecision of the SA and reference ELISAs was σ(δ)=0.52 µg/mL and the biases for Liquichek™ 1, 2 and 3 were 0.66, 0.14 and -0.67 µg/mL, respectively. Thus, unlike the SA, the IA method measures sTfR with the same bias as the reference ELISAs. Combined magnetic separation and detection of nutrition biomarkers on PC biosensors represents a facile method for their accurate and reliable quantification in complex matrixes. PMID:26232676

  6. Study and development of label-free optical biosensors for biomedical applications

    NASA Astrophysics Data System (ADS)

    Choi, Charles J.

    For the majority of assays currently performed, fluorescent or colorimetric chemical labels are commonly attached to the molecules under study so that they may be readily visualized. The methods of using labels to track biomolecular binding events are very sensitive and effective, and are employed as standardized assay protocol across research labs worldwide. However, using labels induces experimental uncertainties due to the effect of the label on molecular conformation, active binding sites, or inability to find an appropriate label that functions equivalently for all molecules in an experiment. Therefore, the ability to perform highly sensitive biochemical detection without the use of fluorescent labels would further simplify assay protocols and would provide quantitative kinetic data, while removing experimental artifacts from fluorescent quenching, shelf-life, and background fluorescence phenomena. In view of the advantages mentioned above, the study and development of optical label-free sensor technologies have been undertaken here. In general, label-free photonic crystal (PC) biosensors and metal nanodome array surface-enhanced Raman scattering (SERS) substrates, both of which are fabricated by nanoreplica molding process, have been used as the method to attack the problem. Chapter 1 shows the work on PC label-free biosensor incorporated microfluidic network for bioassay performance enhancement and kinetic reaction rate constant determination. Chapter 2 describes the work on theoretical and experimental comparison of label-free biosensing in microplate, microfluidic, and spot-based affinity capture assays. Chapter 3 shows the work on integration of PC biosensor with actuate-to-open valve microfluidic chip for pL-volume combinatorial mixing and screening application. In Chapter 4, the development and characterization of SERS nanodome array is shown. Lastly, Chapter 5 describes SERS nanodome sensor incorporated tubing for point-of-care monitoring of

  7. India-Eurasia collision triggers formation of an oceanic microplate

    NASA Astrophysics Data System (ADS)

    Matthews, Kara; Müller, Dietmar; Sandwell, David

    2016-04-01

    Detailed mapping of seafloor tectonic fabric in the Indian Ocean, using high-resolution satellite-derived vertical gravity gradient data, reveals an extinct Pacific-style oceanic microplate - the Mammerickx Microplate - west of the Ninetyeast Ridge. It is one of the first Pacific-style microplates to be mapped outside the Pacific basin, suggesting that geophysical conditions during formation probably resembled those that have dominated at eastern Pacific ridges. The microplate formed at the Indian-Antarctic ridge and is bordered by an extinct ridge in the north and pseudofault in the south, whose conjugate is located north of the Kerguelen Plateau. Independent microplate rotation is indicated by asymmetric pseudofaults and rotated abyssal hill fabric, also identified in multibeam data. Magnetic anomaly picks and age estimates calculated from published spreading rates suggest formation during chron 21o (~47.3 Ma). Plate reorganizations can trigger ridge propagation and microplate development, and we propose that formation of the Mammerickx Microplate is linked with the initial 'soft' stage of the India-Eurasia collision. The collision altered the stress regime at the Indian-Antarctic ridge, leading to a change in segmentation and ridge propagation from an establishing transform fault. Fast Indian-Antarctic spreading that preceded microplate formation, and Kerguelen Plume activity may have facilitated ridge propagation via the production of thin and weak lithosphere. However, both factors had been present for tens of millions of years and are therefore unlikely to have triggered the event. Prior to the collision, this combination of fast spreading and plume activity was responsible for the production of a wide region of undulate seafloor to the north of the extinct ridge and 'W' shaped lineations that record back and forth ridge propagation. Microplate formation provides a means of dating the onset of the India-Eurasia collision, and is completely independent of and

  8. Microfabricated glucose biosensor for culture well operation.

    PubMed

    Pemberton, R M; Cox, T; Tuffin, R; Sage, I; Drago, G A; Biddle, N; Griffiths, J; Pittson, R; Johnson, G; Xu, J; Jackson, S K; Kenna, G; Luxton, R; Hart, J P

    2013-04-15

    A water-based carbon screen-printing ink formulation, containing the redox mediator cobalt phthalocyanine (CoPC) and the enzyme glucose oxidase (GOx), was investigated for its suitability to fabricate glucose microbiosensors in a 96-well microplate format: (1) the biosensor ink was dip-coated onto a platinum (Pt) wire electrode, leading to satisfactory amperometric performance; (2) the ink was deposited onto the surface of a series of Pt microelectrodes (10-500 μm diameter) fabricated on a silicon substrate using MEMS (microelectromechanical systems) microfabrication techniques: capillary deposition proved to be successful; a Pt microdisc electrode of ≥100 μm was required for optimum biosensor performance; (3) MEMS processing was used to fabricate suitably sized metal (Pt) tracks and pads onto a silicon 96 well format base chip, and the glucose biosensor ink was screen-printed onto these pads to create glucose microbiosensors. When formed into microwells, using a 340 μl volume of buffer, the microbiosensors produced steady-state amperometric responses which showed linearity up to 5 mM glucose (CV=6% for n=5 biosensors). When coated, using an optimised protocol, with collagen in order to aid cell adhesion, the biosensors continued to show satisfactory performance in culture medium (linear range to 2 mM, dynamic range to 7 mM, CV=5.7% for n=4 biosensors). Finally, the operation of these collagen-coated microbiosensors, in 5-well 96-well format microwells, was tested using a 5-channel multipotentiostat. A relationship between amperometric response due to glucose, and cell number in the microwells, was observed. These results indicate that microphotolithography and screen-printing techniques can be combined successfully to produce microbiosensors capable of monitoring glucose metabolism in 96 well format cell cultures. The potential application areas for these microbiosensors are discussed. PMID:23265827

  9. A living cell quartz crystal microbalance biosensor for continuous monitoring of cytotoxic responses of macrophages to single-walled carbon nanotubes

    PubMed Central

    2011-01-01

    Background Numerous engineered nanomaterials (ENMs) exist and new ENMs are being developed. A challenge to nanotoxicology and environmental health and safety is evaluating toxicity of ENMs before they become widely utilized. Cellular assays remain the predominant test platform yet these methods are limited by using discrete time endpoints and reliance on organic dyes, vulnerable to interference from ENMs. Label-free, continuous, rapid response systems with biologically meaningful endpoints are needed. We have developed a device to detect and monitor in real time responses of living cells to ENMs. The device, a living cell quartz crystal microbalance biosensor (QCMB), uses macrophages adherent to a quartz crystal. The communal response of macrophages to treatments is monitored continuously as changes in crystal oscillation frequency (Δf). We report the ability of this QCMB to distinguish benign from toxic exposures and reveal unique kinetic information about cellular responses to varying doses of single-walled carbon nanotubes (SWCNTs). Results We analyzed macrophage responses to additions of Zymosan A, polystyrene beads (PBs) (benign substances) or SWCNT (3-150 μg/ml) in the QCMB over 18 hrs. In parallel, toxicity was monitored over 24/48 hrs using conventional viability assays and histological stains to detect apoptosis. In the QCMB, a stable unchanging oscillation frequency occurred when cells alone, Zymosan A alone, PBs alone or SWCNTs without cells at the highest dose alone were used. With living cells in the QCMB, when Zymosan A, PBs or SWCNTs were added, a significant decrease in frequency occurred from 1-6 hrs. For SWCNTs, this Δf was dose-dependent. From 6-18 hrs, benign substances or low dose SWCNT (3-30 μg/ml) treatments showed a reversal of the decrease of oscillation frequency, returning to or exceeding pre-treatment levels. Cell recovery was confirmed in conventional assays. The lag time to see the Δf reversal in QCMB plots was linearly SWCNT

  10. Analysis of ultra-high sensitivity configuration in chip-integrated photonic crystal microcavity bio-sensors

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Hosseini, Amir; Xu, Xiaochuan; Zhu, Liang; Zou, Yi; Chen, Ray T.

    2014-05-01

    We analyze the contributions of quality factor, fill fraction, and group index of chip-integrated resonance microcavity devices, to the detection limit for bulk chemical sensing and the minimum detectable biomolecule concentration in biosensing. We analyze the contributions from analyte absorbance, as well as from temperature and spectral noise. Slow light in two-dimensional photonic crystals provide opportunities for significant reduction of the detection limit below 1 × 10-7 RIU (refractive index unit) which can enable highly sensitive sensors in diverse application areas. We demonstrate experimentally detected concentration of 1 fM (67 fg/ml) for the binding between biotin and avidin, the lowest reported till date.

  11. 3D photonic crystal-based biosensor functionalized with quantum dot-based aptamer for thrombine detection

    NASA Astrophysics Data System (ADS)

    Lim, Chae Young; Choi, Eunpyo; Park, Youngkyu; Park, Jungyul

    2013-05-01

    In this paper, we propose a new technique for protein detection by using the enhancement of intensity in quantum dots (Qdot) whose emission is guided by 3D photonic crystal (PC) structures. For easy to use, we design the emitted light from the sensor can be recovered, when the chemical antibody (aptamer) conjugated with guard DNA (g-DNA) labeled with a quencher (Black FQ) hybridizes with the target proteins. In detail, we synthesis a Qdot-aptamer complex and then immobilize these complex on the PC surfaces. Next, we perform the hybridization of the Qdot-aptamer complex with g-DNA labeled with the quencher. It induces the quenching effect of fluoresce intensity in the Qdot-aptamer. In presence of target protein (thrombin), the Qdot-aptamer complex prefers to form the thrombin-aptamer complex: this results in the release of Black FQ-g-DNA and the quenched light intensity recovers into the original high intensity with Qdot. The intensity recovery varies quantitatively according to the level of the target protein concentration. This proposed sensor shows much higher detection sensitivity than the general fluorescent detection mechanism, which is functionalized on the flat surfaces because of the light guiding effect from 3D photonic crystal structures.

  12. Analysis of ultra-high sensitivity configuration in chip-integrated photonic crystal microcavity bio-sensors

    SciTech Connect

    Chakravarty, Swapnajit Hosseini, Amir; Xu, Xiaochuan; Zhu, Liang; Zou, Yi; Chen, Ray T.

    2014-05-12

    We analyze the contributions of quality factor, fill fraction, and group index of chip-integrated resonance microcavity devices, to the detection limit for bulk chemical sensing and the minimum detectable biomolecule concentration in biosensing. We analyze the contributions from analyte absorbance, as well as from temperature and spectral noise. Slow light in two-dimensional photonic crystals provide opportunities for significant reduction of the detection limit below 1 × 10{sup −7} RIU (refractive index unit) which can enable highly sensitive sensors in diverse application areas. We demonstrate experimentally detected concentration of 1 fM (67 fg/ml) for the binding between biotin and avidin, the lowest reported till date.

  13. Liquid-Crystal Biosensor Based on Nickel-Nanosphere-Induced Homeotropic Alignment for the Amplified Detection of Thrombin.

    PubMed

    Zhao, Dongyu; Peng, Yi; Xu, Lihong; Zhou, Wei; Wang, Qian; Guo, Lin

    2015-10-28

    A new liquid-crystal (LC)-based sensor operated by nickel nanosphere (NiNS)-induced homeotropic alignment for the label-free monitoring of thrombin was reported. When doped with NiNSs, a uniform vertical orientation of 4-cyano-4'-pentylbiphenyl (5CB) was easily obtained. A sandwich system of aptamer/thrombin/aptamer-functionalized gold nanoparticles (AuNPs) was fabricated, and AuNPs-aptamer conjugation caused the disruption of the 5CB orientation, leading to an obvious change of the optical appearance from a dark to a bright response to thrombin concentrations from 0.1 to 100 nM. This design also allowed quantitative detection of the thrombin concentration. This distinctive and sensitive thrombin LC sensor provides a new principle for building LC-sensing systems. PMID:26458050

  14. Biosensor of endotoxin and sepsis

    NASA Astrophysics Data System (ADS)

    Shao, Yang; Wang, Xiang; Wu, Xi; Gao, Wei; He, Qing-hua; Cai, Shaoxi

    2001-09-01

    To investigate the relation between biosensor of endotoxin and endotoxin of plasma in sepsis. Method: biosensor of endotoxin was designed with technology of quartz crystal microbalance bioaffinity sensor ligand of endotoxin were immobilized by protein A conjugate. When a sample soliton of plasma containing endotoxin 0.01, 0.03, 0.06, 0.1, 0.5, 1.0Eu, treated with perchloric acid and injected into slot of quartz crystal surface respectively, the ligand was released from the surface of quartz crystal to form a more stable complex with endotoxin in solution. The endotoxin concentration corresponded to the weight change on the crystal surface, and caused change of frequency that occurred when desorbed. The result was biosensor of endotoxin might detect endotoxin of plasma in sepsis, measurements range between 0.05Eu and 0.5Eu in the stop flow mode, measurement range between 0.1Eu and 1Eu in the flow mode. The sensor of endotoxin could detect the endotoxin of plasm rapidly, and use for detection sepsis in clinically.

  15. Absorbance and fluorometric sensing with capillary wells microplates

    SciTech Connect

    Tan, Han Yen; Cheong, Brandon Huey-Ping; Neild, Adrian; Wah Ng, Tuck; Liew, Oi Wah

    2010-12-15

    Detection and readout from small volume assays in microplates are a challenge. The capillary wells microplate approach [Ng et al., Appl. Phys. Lett. 93, 174105 (2008)] offers strong advantages in small liquid volume management. An adapted design is described and shown here to be able to detect, in a nonimaging manner, fluorescence and absorbance assays minus the error often associated with meniscus forming at the air-liquid interface. The presence of bubbles in liquid samples residing in microplate wells can cause inaccuracies. Pipetting errors, if not adequately managed, can result in misleading data and wrong interpretations of assay results; particularly in the context of high throughput screening. We show that the adapted design is also able to detect for bubbles and pipetting errors during actual assay runs to ensure accuracy in screening.

  16. Biosensor utilizing a liquid crystal/water interface functionalized with poly(4-cyanobiphenyl-4'-oxyundecylacrylate-b-((2-dimethyl amino) ethyl methacrylate)).

    PubMed

    Omer, Muhammad; Khan, Mashooq; Kim, Young Kyoo; Lee, Joon Hyung; Kang, Inn-Kyu; Park, Soo-Young

    2014-09-01

    The interface between the nematic liquid crystal, 4-cyano-4'-pentylbiphenyl (5CB) and water within a transmission electron microscopy (TEM) grid cell coated with the pH-dependent weak cationic amphiphilic block copolymer poly((4-cyanobiphenyl-4'-oxyundecylacrylate)-b-((2-dimethyl amino) ethyl methacrylate)) (LCP-b-PDMAEMA) (which was successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization) was subsequently evaluated for protein and deoxyribonucleic acid (DNA) detection. The LCP-b-PDMAEMA monolayer was fabricated using a Langmuir Blodgett trough, transferred to the 5CB-filled TEM grid, and placed on the octadecyltrichlorosilane-coated glass (TEMPDMAEMA) in such a way that the LCP chains were immersed in the 5CB while the PDMAEMA chains were pointed away from the 5CB surface and immersed in water. Several model proteins such as bovine serum albumin (BSA), hemoglobin (Hb), and chymotrypsinogen (ChTg) were tested at pH values ranging from 2 to 12 to determine the role of the charge state of the protein on protein detection by a weak polyelectrolyte such as PDMAEMA. PDMAEMA contains cationic and neutral states below and above the pKa value, respectively, and is thus able to absorb proteins below its pKa threshold through electrostatic interactions. BSA exhibited a homeotropic to planar (H-P) change in orientation within the TEMPDMAEMA grid cell at concentrations greater than 0.02wt% within the pH range between the isoelectric point (pI) of BSA and the pKa of PDMAEMA, where the charge states of BSA and PDMAEMA were negative and positive, respectively. However, this change in orientation did not occur with other proteins that exhibited a pI higher than the pKa of PDMAEMA due to the electrostatic repulsions resulting from their same cationic charges. This result indicates that the electrostatic interactions between proteins and PDMAEMA are a major contributing factor for protein detection by the H-P transformation within the

  17. Surface oxide effect on optical sensing and photoelectric conversion of α-In2Se3 hexagonal microplates.

    PubMed

    Ho, Ching-Hwa; Lin, Chien-Hao; Wang, Yi-Ping; Chen, Ying-Cen; Chen, Shin-Hong; Huang, Ying-Sheng

    2013-03-01

    The surface formation oxide assists of visible to ultraviolet photoelectric conversion in α-In2Se3 hexagonal microplates has been explored. Hexagonal α-In2Se3 microplates with the sizes of 10s to 100s of micrometers were synthesized and prepared by the chemical vapor transport method using ICl3 as a transport agent. Many vacancies and surface imperfection states have been found in the bulk and on the surface of the microplate because of the intrinsic defect nature of α-In2Se3. To discover physical and chemical properties and finding technological uses of α-In2Se3, several experiments including transmission electron miscopy (TEM), X-ray photoelectron spectroscopy (XPS), surface photovoltage (SPV), photoluminescence (PL), surface photoresponse (SPR), photoconductivity (PC), and thermoreflectance (TR) measurements have been carried out. Experimental results of TEM, XPS, SPV, PL, and SPR measurements show that a surface oxidation layer α-In2Se3-3xO3x (0 ≤ x ≤ 1) has formed on the crystal face of α-In2Se3 in environmental air with the inner layer content close to In2Se3 but the outermost layer content approaching In2O3. The near band edge transitions of α-In2Se3 microplates have been probed experimentally by TR and PC measurements. The direct band gap of α-In2Se3 has been determined to be 1.453 eV. The SPV result shows a maximum quantum efficiency of the surface oxide α-In2Se3-3xO3x (0 ≤ x ≤ 1) that presents a peak photoresponse near 2.18 eV. The analyses of SPV, SPR, PL, TR, and PC measurements revealed that the surface oxide layer facilitates the conversion of the ultraviolet to the visible range while the native defects (Se and In vacancies) sustain photoconductivity in the near-infrared region. On the basis of the experimental results a wide-energy-range photodetector that combines PC- and SPR-mode operations for α-In2Se3 microplate has been made. The testing results show a well-behaved function of photoelectric conversion in the near-infrared to

  18. Microplate Bioassay for Determining Substrate Selectivity of "Candida rugosa" Lipase

    ERIC Educational Resources Information Center

    Wang, Shi-zhen; Fang, Bai-shan

    2012-01-01

    Substrate selectivity of "Candida rugosa" lipase was tested using "p"-nitrophenyl esters of increasing chain length (C[subscript 1], C[subscript 7], C[subscript 15]) using the high-throughput screening method. A fast and easy 96-well microplate bioassay was developed to help students learn and practice biotechnological specificity screen. The…

  19. The origin of the Iberian microplate high topography

    NASA Astrophysics Data System (ADS)

    Quintana, L.; Pulgar, J. A.; Alonso, J. L.; Fernandez Viejo, G.

    2013-12-01

    The Iberian microplate is about 1100 km width, 3500 km long, and experienced contraction during the Cenozoic convergence of the Eurasian and African plates. In this process two main mountain ranges were created in the boundaries of the microplate: the Cantabrian-Pyrenean range in the north and the Betic-Rif orogenic system in the south, with a maximun height of 3479 m over sea level. However, in the interior of the microplate there is also several ranges and plateaus, with maximun heights of 2592 m. The origin of these interior high topography is controversial and has been explained by means of several procesess as: a) transference of displacement from the south border of the microplate, b) lithospheric folding, or c) more complex deep mantle related processes. In this work we investigate the relation between the northern border range of the microplate and some Iberian interior reliefs as: a) the Spanish Central System range, located in the central part of the microplate, with peaks over 2500 m, and b) the North-Iberian meseta, situated between these two ranges, and with average heights of 750 m. In order to solve this relation we have built a crustal-scale cross-section, through the northern half of the Iberian microplate, by using field geological mapping, subsoil information and deep geophysical data. The section acroos the central part of the Cantabrian range shows the well-known Iberian microplate continental subduction beneath the Eurasian plate, with a prominent crustal root that reaches up to 45 km depth. In this section an important difference between the upper and lower crust shortening values has been found. Thus, the upper crust has been shortened 97 km while the lower crust 122 km. The section across de Central System range shows a slightly thickened crust. In this range also exist a difference in the shortening values between upper and lower crust, but in the contrary sense than the Cantabrian range. Thus, the Central System range has been shortened

  20. Application of Optical Biosensors in Small-Molecule Screening Activities

    PubMed Central

    Geschwindner, Stefan; Carlsson, Johan F.; Knecht, Wolfgang

    2012-01-01

    The last two decades have seen remarkable progress and improvements in optical biosensor systems such that those are currently seen as an important and value-adding component of modern drug screening activities. In particular the introduction of microplate-based biosensor systems holds the promise to match the required throughput without compromising on data quality thus representing a sought-after complement to traditional fluidic systems. This article aims to highlight the application of the two most prominent optical biosensor technologies, namely surface plasmon resonance (SPR) and optical waveguide grating (OWG), in small-molecule screening and will present, review and discuss the advantages and disadvantages of different assay formats on these platforms. A particular focus will be on the specific advantages of the inhibition in solution assay (ISA) format in contrast to traditional direct binding assays (DBA). Furthermore we will discuss different application areas for both fluidic as well as plate-based biosensor systems by considering the individual strength of the platforms. PMID:22666031

  1. Cryoalgotox: Use of cryopreserved alga in a semistatic microplate test

    SciTech Connect

    Benhra, A.; Radetski, C.M.; Ferard, J.F.

    1997-03-01

    Use of cryopreserved alga Selenastrum capricornutum has been evaluated as a simple and cost-efficient procedure in a new semistatic algal ecotoxicity test. Experiments have been conducted to compare performance criteria of this method, named Cryoalgotox, versus the classic microplate test using fresh algae. Cryoalgotox 72-h 50% effective concentrations (EC50s) determined with Cd{sup 2+}, Cu{sup 2+}, Cr{sup 6+}, and atrazine were more sensitive, repeatable (low coefficients of variation), and reproducible (low time effect) than the results obtained with the classical microplate tests. The effect of storage time at {minus}80 C on the sensitivity of the algae was assessed using cadmium as a toxic reference; it was shown that algae stored at {minus}80 C over a 3-month period gave comparable toxicity results to those found with fresh algae.

  2. Microplate based biosensing with a computer screen aided technique.

    PubMed

    Filippini, Daniel; Andersson, Tony P M; Svensson, Samuel P S; Lundström, Ingemar

    2003-10-30

    Melanophores, dark pigment cells from the frog Xenopus laevis, have the ability to change light absorbance upon stimulation by different biological agents. Hormone exposure (e.g. melatonin or alpha-melanocyte stimulating hormone) has been used here as a reversible stimulus to test a new compact microplate reading platform. As an application, the detection of the asthma drug formoterol in blood plasma samples is demonstrated. The present system utilizes a computer screen as a (programmable) large area light source, and a standard web camera as recording media enabling even kinetic microplate reading with a versatile and broadly available platform, which suffices to evaluate numerous bioassays. Especially in the context of point of care testing or self testing applications these possibilities become advantageous compared with highly dedicated comparatively expensive commercial systems. PMID:14558996

  3. Biochemical characterization and immobilization of Erwinia carotovoral-asparaginase in a microplate for high-throughput biosensing of l-asparagine.

    PubMed

    Labrou, Nikolaos E; Muharram, Magdy Mohamed

    2016-10-01

    l-Asparaginases (l-ASNase, E.C. 3.5.1.1) catalyze the conversion of l-asparagine to l-aspartic acid and ammonia. In the present work, a new form of l-ASNase from a strain of Erwinia carotovora (EcaL-ASNase) was cloned, expressed in Escherichia coli as a soluble protein and characterized. The enzyme was purified to homogeneity by a single-step procedure comprising ion-exchange chromatography. The properties of the recombinant enzyme were investigated employing kinetic analysis and molecular modelling and the kinetic parameters (Km, kcat) were determined for a number of substrates. The enzyme was used to assemble a microplate-based biosensor that was used for the development of a simple assay for the determination of l-asparagine in biological samples. In this sensor, the enzyme was immobilized by crosslinking with glutaraldehyde and deposited into the well of a microplate in 96-well format. The sensing scheme was based on the colorimetric measurement of ammonia formation using the Nessler's reagent. This format is ideal for micro-volume applications and allows the use of the proposed biosensor in high-throughput applications for monitoring l-asparagine levels in serum and foods samples. Calibration curve was obtained for l-asparagine, with useful concentration range 10-200μΜ. The biosensor had a detection limit of 10μM for l-asparagine. The method's reproducibility was in the order of ±3-6% and l-asparagine mean recoveries were 101.5%. PMID:27542748

  4. Semi-automated microplate monitoring of protein polymerization and aggregation.

    PubMed

    Garcia, Veronica M; Rowlett, Veronica W; Margolin, William; Morano, Kevin A

    2016-09-01

    Static light scattering (SLS) is a commonly used technique for monitoring dynamics of high molecular weight protein complexes such as protein oligomers or aggregates. However, traditional methods are limited to testing a single condition and typically require large amounts of protein and specialized equipment. We show that a standard microplate reader can be used to characterize the molecular dynamics of different types of protein complexes, with the multiple advantages of microscale experimental volumes, semi-automated protocols and highly parallel processing. PMID:27251433

  5. Optimization of phagocyte chemiluminescence measurements using microplates and vials.

    PubMed

    Hengster, P; Kunc, M; Linke, R; Eberl, T; Steurer, W; Ofner, D; Berthold, F; Margreiter, R

    1999-01-01

    In order to cope with large amounts of samples for chemiluminescence (CL), vials were replaced with microplates. Although various types of plates have been commercially available for quite some time and the free-plate mode is advocated by the producer of the counter, little is known about their impact on the outcome of CL measurements. We tested two different 24-well microplates and six different 96-well microplates in two different luminometers, and results were compared with those achieved with vials. Before these comparative tests, we attempted to optimize measurement conditions. CL sensitivity was highest with luminol concentrations of 0.8-3.3 micromol/L, PMA concentrations of 0.06-80 micromol/L, a pH value of 10 and a temperature of 20 degrees C. An indirect correlation was found between fluid volume and yield in counts: the lower the volume, the higher the counts. With regard to sensitivity and cross-talk, the 96-well Isoplatetrade mark was superior to all other plates tested. While all white plates tested gave acceptable results, usage of the black 96-well plates resulted in an extremely low sensitivity. Plates designed for cell culturing gave even lower counts and a cross-talk of up to 31%. All attempts to reduce cross-talk and improve sensitivity, such as aluminium foil or grids, irrespective of the position of the photomultiplier, did not give results comparable to the original 96-well isoplate. Our results suggest that, with the exception of black 96-well microplates and cell culture plates, all other plates tested have a sufficient sensitivity when compared to vials and acceptable cross-talk, the 96-well Isoplatetrade mark being the best. Both types of luminometers used gave reproducible results, Wallac having a somewhat higher sensitivity, Canberra Packard somewhat less cross-talk. PMID:10398566

  6. Quantitative Microplate-Based Respirometry with Correction for Oxygen Diffusion

    PubMed Central

    2009-01-01

    Respirometry using modified cell culture microplates offers an increase in throughput and a decrease in biological material required for each assay. Plate based respirometers are susceptible to a range of diffusion phenomena; as O2 is consumed by the specimen, atmospheric O2 leaks into the measurement volume. Oxygen also dissolves in and diffuses passively through the polystyrene commonly used as a microplate material. Consequently the walls of such respirometer chambers are not just permeable to O2 but also store substantial amounts of gas. O2 flux between the walls and the measurement volume biases the measured oxygen consumption rate depending on the actual [O2] gradient. We describe a compartment model-based correction algorithm to deconvolute the biological oxygen consumption rate from the measured [O2]. We optimize the algorithm to work with the Seahorse XF24 extracellular flux analyzer. The correction algorithm is biologically validated using mouse cortical synaptosomes and liver mitochondria attached to XF24 V7 cell culture microplates, and by comparison to classical Clark electrode oxygraph measurements. The algorithm increases the useful range of oxygen consumption rates, the temporal resolution, and durations of measurements. The algorithm is presented in a general format and is therefore applicable to other respirometer systems. PMID:19555051

  7. GPS estimates of microplate motions, northern Caribbean: evidence for a Hispaniola microplate and implications for earthquake hazard

    NASA Astrophysics Data System (ADS)

    Benford, B.; DeMets, C.; Calais, E.

    2012-09-01

    We use elastic block modelling of 126 GPS site velocities from Jamaica, Hispaniola, Puerto Rico and other islands in the northern Caribbean to test for the existence of a Hispaniola microplate and estimate angular velocities for the Gônave, Hispaniola, Puerto Rico-Virgin Islands and two smaller microplates relative to each other and the Caribbean and North America plates. A model in which the Gônave microplate spans the whole plate boundary between the Cayman spreading centre and Mona Passage west of Puerto Rico is rejected at a high confidence level. The data instead require an independently moving Hispaniola microplate between the Mona Passage and a likely diffuse boundary within or offshore from western Hispaniola. Our updated angular velocities predict 6.8 ± 1.0 mm yr-1 of left-lateral slip along the seismically hazardous Enriquillo-Plantain Garden fault zone of southwest Hispaniola, 9.8 ± 2.0 mm yr-1 of slip along the Septentrional fault of northern Hispaniola and ˜14-15 mm yr-1 of left-lateral slip along the Oriente fault south of Cuba. They also predict 5.7 ± 1 mm yr-1 of fault-normal motion in the vicinity of the Enriquillo-Plantain Garden fault zone, faster than previously estimated and possibly accommodated by folds and faults in the Enriquillo-Plantain Garden fault zone borderlands. Our new and a previous estimate of Gônave-Caribbean plate motion suggest that enough elastic strain accumulates to generate one to two Mw˜ 7 earthquakes per century along the Enriquillo-Plantain Garden and nearby faults of southwest Hispaniola. That the 2010 M= 7.0 Haiti earthquake ended a 240-yr-long period of seismic quiescence in this region raises concerns that it could mark the onset of a new earthquake sequence that will relieve elastic strain that has accumulated since the late 18th century.

  8. Maximizing Photoluminescence Extraction in Silicon Photonic Crystal Slabs.

    PubMed

    Mahdavi, Ali; Sarau, George; Xavier, Jolly; Paraïso, Taofiq K; Christiansen, Silke; Vollmer, Frank

    2016-01-01

    Photonic crystal modes can be tailored for increasing light matter interactions and light extraction efficiencies. These PhC properties have been explored for improving the device performance of LEDs, solar cells and precision biosensors. Tuning the extended band structure of 2D PhC provides a means for increasing light extraction throughout a planar device. This requires careful design and fabrication of PhC with a desirable mode structure overlapping with the spectral region of emission. We show a method for predicting and maximizing light extraction from 2D photonic crystal slabs, exemplified by maximizing silicon photoluminescence (PL). Systematically varying the lattice constant and filling factor, we predict the increases in PL intensity from band structure calculations and confirm predictions in micro-PL experiments. With the near optimal design parameters of PhC, we demonstrate more than 500-fold increase in PL intensity, measured near band edge of silicon at room temperature, an enhancement by an order of magnitude more than what has been reported. PMID:27113674

  9. Maximizing Photoluminescence Extraction in Silicon Photonic Crystal Slabs

    PubMed Central

    Mahdavi, Ali; Sarau, George; Xavier, Jolly; Paraïso, Taofiq K.; Christiansen, Silke; Vollmer, Frank

    2016-01-01

    Photonic crystal modes can be tailored for increasing light matter interactions and light extraction efficiencies. These PhC properties have been explored for improving the device performance of LEDs, solar cells and precision biosensors. Tuning the extended band structure of 2D PhC provides a means for increasing light extraction throughout a planar device. This requires careful design and fabrication of PhC with a desirable mode structure overlapping with the spectral region of emission. We show a method for predicting and maximizing light extraction from 2D photonic crystal slabs, exemplified by maximizing silicon photoluminescence (PL). Systematically varying the lattice constant and filling factor, we predict the increases in PL intensity from band structure calculations and confirm predictions in micro-PL experiments. With the near optimal design parameters of PhC, we demonstrate more than 500-fold increase in PL intensity, measured near band edge of silicon at room temperature, an enhancement by an order of magnitude more than what has been reported. PMID:27113674

  10. A Cenozoic tectonic model for Southeast Asia - microplates and basins

    SciTech Connect

    Maher, K.A.

    1995-04-01

    A computer-assisted Cenozoic tectonic model was built for Southeast Asia and used to construct 23 base maps, 2 to 6 million years apart. This close temporal spacing was necessary to constrain all the local geometric shifts in a consistent and geologically feasible fashion. More than a hundred individual blocks were required to adequately treat Cenozoic microplate processes at a basic level. The reconstructions show tectonic evolution to be characterized by long periods of gradual evolution, interrupted by brief, widespread episodes of reorganization in fundamental plate geometries and kinematics. These episodes are triggered by major collisions, or by accumulation of smaller changes. The model takes into account difficulties inherent in the region. The Pacific and Indo-Australian plates and their predecessors have driven westward and northward since the late Paleozoic, towards each other and the relatively stationary backstop of Asia. Southeast Asia is therefore the result of a long-lived, complex process of convergent tectonics, making it difficult to reconstruct tectonic evolution as much of the continental margin and sea floor spreading record was erased. In addition, the region has been dominated by small-scale microplate processes with short time scales and internal deformation, taking place in rapidly evolving and more ductile buffer zones between the major rigid plate systems. These plate interaction zones have taken up much of the relative motion between the major plates. Relatively ephemeral crustal blocks appear and die within the buffer zones, or accrete to and disperse from the margins of the major plate systems. However, such microplate evolution is the dominant factor in Cenozoic basin evolution. This detailed testonic model aids in comprehension and prediction of basin development, regional hydrocarbon habitat, and petroleum systems.

  11. Nano- and microsized zeolites as a perspective material for potentiometric biosensors creation.

    PubMed

    Soldatkin, Oleksandr O; Shelyakina, Margaryta K; Arkhypova, Valentyna N; Soy, Esin; Kirdeciler, Salih Kaan; Ozansoy Kasap, Berna; Lagarde, Florence; Jaffrezic-Renault, Nicole; Akata Kurç, Burcu; Soldatkin, Alexei P; Dzyadevych, Sergei V

    2015-01-01

    A number of potentiometric biosensors based on coimmobilization of enzymes with different types of zeolite on pH-ion-sensitive field-effect transistor (ISFET) have been developed. Their working characteristics have been determined and compared. It was shown that clinoptilolite and zeolite Beta polymorph A (BEA) are more promising for creating biosensors than zeolite A. Changing the concentration of zeolite BEA in membranes, it is possible to extend the biosensor linear measurement range. The two-layer method of deposition of the enzyme with clinoptilolite was found to provide a significant increase in the biosensor sensitivity to substrates, whereas thermal modification of the zeolite BEA crystals can improve analytical characteristics of potentiometric biosensors for detection of toxic substances. These results show that it is possible to regulate the ISFET characteristics for different enzyme-based biosensors by tailoring the electrode surfaces via different zeolites. This makes zeolites strong candidates for integration into biosensors as ISFET modifiers. PMID:25852356

  12. Piezoelectric Biosensors for Organophosphate and Carbamate Pesticides: A Review

    PubMed Central

    Marrazza, Giovanna

    2014-01-01

    Due to the great amount of pesticides currently being used, there is an increased interest for developing biosensors for their detection. Among all the physical transducers, piezoelectric systems have emerged as the most attractive due to their simplicity, low instrumentation costs, possibility for real-time and label-free detection and generally high sensitivity. This paper presents an overview of biosensors based on the quartz crystal microbalance, which have been reported in the literature for organophosphate and carbamate pesticide analysis. PMID:25587424

  13. Biosensors for Cell Analysis.

    PubMed

    Zhou, Qing; Son, Kyungjin; Liu, Ying; Revzin, Alexander

    2015-01-01

    Biosensors first appeared several decades ago to address the need for monitoring physiological parameters such as oxygen or glucose in biological fluids such as blood. More recently, a new wave of biosensors has emerged in order to provide more nuanced and granular information about the composition and function of living cells. Such biosensors exist at the confluence of technology and medicine and often strive to connect cell phenotype or function to physiological or pathophysiological processes. Our review aims to describe some of the key technological aspects of biosensors being developed for cell analysis. The technological aspects covered in our review include biorecognition elements used for biosensor construction, methods for integrating cells with biosensors, approaches to single-cell analysis, and the use of nanostructured biosensors for cell analysis. Our hope is that the spectrum of possibilities for cell analysis described in this review may pique the interest of biomedical scientists and engineers and may spur new collaborations in the area of using biosensors for cell analysis. PMID:26274599

  14. Calcofluor fluorescence assay for wort beta-glucan in a microplate format

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The widely-used fluorescent (Calcofluor) flow injection analysis method for determining the concentrations of beta-glucans in Congress worts from barley malts is adapted to microplate format. Adaptation of the Calcofluor assay to use widely available fluorescent microplate readers makes the assay m...

  15. Tectonics and evolution of the Juan Fernandez microplate at the Pacific-Nazca-Antarctic triple junction

    NASA Technical Reports Server (NTRS)

    Anderson-Fontana, S.; Larson, R. L.; Engein, J. F.; Lundgren, P.; Stein, S.

    1986-01-01

    Magnetic and bathymetric profiles derived from the R/V Endeavor survey and focal mechanism studies for earthquakes on two of the Juan Fernandez microplate boundaries are analyzed. It is observed that the Nazca-Juan Fernandez pole is in the northern end of the microplate since the magnetic lineation along the East Ridge of the microplate fans to the south. The calculation of the relative motion of the Juan Fernandez-Pacific-Nazca-Antarctic four-plate system using the algorithm of Minster et al. (1974) is described. The development of tectonic and evolutionary models of the region is examined. The tectonic model reveals that the northern boundary of the Juan Fernandez microplate is a zone of compression and that the West Ridge and southwestern boundary are spreading obliquely; the evolutionary model relates the formation of the Juan Fernandez microplate to differential spreading rates at the triple junction.

  16. Genomagnetic Electrochemical Biosensors

    NASA Astrophysics Data System (ADS)

    Wang, Joseph; Erdem, Arzum

    The use of nucleic acid technologies has significantly improved preparation and diagnostic procedures in life sciences. Nucleic acid layers combined with electrochemical or optical transducers produce a new kind of affinity biosensors as DNA Biosensor for small molecular weight molecules. Electrochemical DNA biosensors are attractive devices for converting the hybridization event into an analytical signal for obtaining sequence-specific information in connection with clinical, environmental or forensic investigations. DNA hybridization biosensors, based on electrochemical transduction of hybridization, couple the high specificity of hybridization reactions with the excellent sensitivity and portability of electrochemical transducers. The main goal in all researches is to design DNA biosensors for preparing a basis for the future DNA microarray system. DNA chip has now become a powerful tool in biological research, however the real clinic assay is still under development. Recently, there has been a great interest to the magnetic beads and/or nanoparticles labelled with metals such as gold, cadmium, silver, etc. for designing of novel electrochemical DNA biosensor approaches resulting in efficient separation. The attractive features of this technology include simple approach, rapid results, multi-analyte detection, low-cost per measurument, stable, and non-hazardous reagents, and reduced waste handling. Some of these new approaches and applications of the electrochemical DNA biosensors based on magnetic beads and its combining with nanoparticles labelled with metals are described and discussed.

  17. Introduction to biosensors

    PubMed Central

    Bhalla, Nikhil; Jolly, Pawan; Formisano, Nello

    2016-01-01

    Biosensors are nowadays ubiquitous in biomedical diagnosis as well as a wide range of other areas such as point-of-care monitoring of treatment and disease progression, environmental monitoring, food control, drug discovery, forensics and biomedical research. A wide range of techniques can be used for the development of biosensors. Their coupling with high-affinity biomolecules allows the sensitive and selective detection of a range of analytes. We give a general introduction to biosensors and biosensing technologies, including a brief historical overview, introducing key developments in the field and illustrating the breadth of biomolecular sensing strategies and the expansion of nanotechnological approaches that are now available. PMID:27365030

  18. Introduction to biosensors.

    PubMed

    Bhalla, Nikhil; Jolly, Pawan; Formisano, Nello; Estrela, Pedro

    2016-06-30

    Biosensors are nowadays ubiquitous in biomedical diagnosis as well as a wide range of other areas such as point-of-care monitoring of treatment and disease progression, environmental monitoring, food control, drug discovery, forensics and biomedical research. A wide range of techniques can be used for the development of biosensors. Their coupling with high-affinity biomolecules allows the sensitive and selective detection of a range of analytes. We give a general introduction to biosensors and biosensing technologies, including a brief historical overview, introducing key developments in the field and illustrating the breadth of biomolecular sensing strategies and the expansion of nanotechnological approaches that are now available. PMID:27365030

  19. Constraints on the Ionian microplate subduction beneath the Tyrrhenian basin

    NASA Astrophysics Data System (ADS)

    Pasquale, V.; Verdoya, M.; Chiozzi, P.

    2003-04-01

    The Tyrrhenian Basin is, from a geodynamical point of view, one of the most intriguing areas of the Central Mediterranean, being affected by still ongoing and not yet fully understood tectonic processes of lithosphere extension and subduction. Its high heat flux, albeit lower than that expected from classical models of plate cooling, together with other pieces of geophysical evidence, argues for a marginal-type basin of very young age. The abyssal plain of the basin is floored with oceanic crust and it is thermally perturbed by strong hydrothermal circulation. The stretched continental margins are affected by volcanic activity, which causes local thermal perturbations by fluid circulation and magma intrusion. The surface heat flux budget on the margins is well balanced only if one envisages an additional thermal contribution of a layer of magma underplating the crust and a lithosphere overlying an anomalously hot asthenosphere. In this paper we supply further constraints on the deformation processes affecting the Ionian microplate subducting beneath the southern part of the basin, on the basis of a joint analysis of the seismic activity and the thermal state. We determined the thermal structure in the descending plate by means of an analytical model taking into account how the slab would heat and the mantle wedge cool with time. A relation between the maximum depth of seismicity of several marginal basins and the thermal parameter of the descending slabs, which depends on the age of the subducted lithosphere and the vertical component of the convergence rate, has been used. The tectonic subsidence of about 6000 m evaluated for the oceanic domain of the Ionian microplate implies a heat flux of 40 mW/m2, which is in agreement with the observed values. By considering that the maximum depth of the seismic events within the slab, a thermal parameter of about 4500 km, was found. The corresponding assimilation and cooling times of the microplate are 13 and 100 My

  20. Nucleation-fibrillation dynamics of Aβ1-40 peptides on liquid-solid surface studied by total-internal-reflection fluorescence microscopy coupled with quartz-crystal microbalance biosensor

    NASA Astrophysics Data System (ADS)

    Hamada, Hiroki; Ogi, Hirotsugu; Noi, Kentaro; Yagi, Hisashi; Goto, Yuji; Hirao, Masahiko

    2015-07-01

    We have successfully developed the total-internal-reflection-fluorescence microscopy combined with a quartz-crystal microbalance (TIRFM-QCM) biosensor, and monitored the nucleation-fibrillation phenomenon of amyloid β1-40 peptide on the naked quartz surface. The cross-β-sheet structures were visualized with the TIRFM using the thioflavin-T (Th-T) label, and other unlabeled aggregates were detected through the frequency change of the 58-MHz wireless-electrodeless QCM throughout the aggregation reaction. The QCM response indicates significant adsorption of the peptides on the quartz surface at the early stage, which is followed by fibrillation. The non-cross-β-sheet oligomers are first formed, and nuclei appear in the oligomer region, from which fibrils originate and elongate. The two-color TIRFM observation was performed after the aggregation reaction with the Nile-red label as well as the ThT label for identifying nucleation from non-β-sheet regions. An aggregation model is proposed.

  1. GMR-based PhC biosensor: FOM analysis and experimental studies

    SciTech Connect

    Syamprasad, Jagadeesh; Narayanan, Roshni; Joseph, Joby; Takahashi, Hiroki; Sandhu, Adarsh; Jindal, Rajeev

    2014-02-20

    Guided Mode Resonance based Photonic crystal biosensor has a lot of potential applications. In our work, we are trying to improve their figure of merit values in order to achieve an optimum level through design and fabrication techniques. A robust and low-cost alternative for current biosensors is also explored through this research.

  2. Oceanic microplate formation records the onset of India-Eurasia collision

    NASA Astrophysics Data System (ADS)

    Matthews, Kara J.; Dietmar Müller, R.; Sandwell, David T.

    2016-01-01

    Mapping of seafloor tectonic fabric in the Indian Ocean, using high-resolution satellite-derived vertical gravity gradient data, reveals an extinct Pacific-style oceanic microplate ('Mammerickx Microplate') west of the Ninetyeast Ridge. It is one of the first Pacific-style microplates to be mapped outside the Pacific basin, suggesting that geophysical conditions during formation probably resembled those that have dominated at eastern Pacific ridges. The microplate formed at the Indian-Antarctic ridge and is bordered by an extinct ridge in the north and pseudofault in the south, whose conjugate is located north of the Kerguelen Plateau. Independent microplate rotation is indicated by asymmetric pseudofaults and rotated abyssal hill fabric, also seen in multibeam data. Magnetic anomaly picks and age estimates calculated from published spreading rates suggest formation during chron 21o (∼47.3 Ma). Plate reorganizations can trigger ridge propagation and microplate development, and we propose that Mammerickx Microplate formation is linked with the India-Eurasia collision (initial 'soft' collision). The collision altered the stress regime at the Indian-Antarctic ridge, leading to a change in segmentation and ridge propagation from an establishing transform. Fast Indian-Antarctic spreading that preceded microplate formation, and Kerguelen Plume activity, may have facilitated ridge propagation via the production of thin and weak lithosphere; however both factors had been present for tens of millions of years and are therefore unlikely to have triggered the event. Prior to the collision, the combination of fast spreading and plume activity was responsible for the production of a wide region of undulate seafloor to the north of the extinct ridge and 'W' shaped lineations that record back and forth ridge propagation. Microplate formation provides a precise means of dating the onset of the India-Eurasia collision, and is completely independent of and complementary to timing

  3. BIOSENSORS FOR ENVIRONMENTAL APPLICATIONS

    EPA Science Inventory

    A review, with 19 references, is given on challenges and possible opportunities for the development of biosensors for environmental monitoring applications. The high cost and slow turnaround times typically associated with the measurement of regulated pollutants clearly indicates...

  4. The western transverse ranges microplate as a native terrane

    SciTech Connect

    Campbell, M.D.; Reed, W.E. )

    1994-04-01

    Palocurrent measurements from the entire Cretaceous section of the western Transverse Ranges microplate (WTRM) yield a northerly flow direction. Point count data indicate a mixed provenance for both conglomerates and associated sandstones. The dominant provenance was mixed magmatic arc/recycled orogen and disected/transitional arc terranes. Petrographic, quantitative SEM and microprobe analysis also indicate the presence of diagnostic Franciscan mineralogy in these sediments, including glaucophane, riebeckite, lawsonite, and serpentine, suggesting derivation from a subduction complex. Olistoclasts of chert, jadeitic graywacke, serpentine and blueschist are found intermixed within the arc-derived sediments. Olistoclasts range in size from sub-millimeter to centimeter scale and olistoliths range up to 150 m. Well preserved internal bedding in some of the olistoliths suggest emplacement by landsliding indicating very short transport distance. This Franciscan material represents the oldest melange-derived material reported from this part of California and documents uplift and erosion of the subduction complex earlier than previously suggested. These data are consistent with deposition in a Cretaceous fore-arc basin located west or south of the San Diego area. The allochthonous WTRM of southern California can be reconstructed to an originally north-south oriented fore-arc basin. After deposition of the Sespe Formation (22 Ma [+-]) the microplate was slivered by strike-slip faults and rotated clockwise approximately 90[degrees], after which, the block again accreted against the continental margin. Our reconstruction suggest that depositional and structural trends for Eocene and Cretaceous sediments is likely to be different from that in the Miocene Monterey pay zones in the Santa Barbara channel region. If our reconstruction is correct, exploration strategy for Eocene and Cretaceous petroleum in the southern California Bight should take this tectonic model into account.

  5. Triggered optical biosensor

    DOEpatents

    Song, Xuedong; Swanson, Basil I.

    2001-10-02

    An optical biosensor is provided for the detection of a multivalent target biomolecule, the biosensor including a substrate having a bilayer membrane thereon, a recognition molecule situated at the surface, the recognition molecule capable of binding with the multivalent target biomolecule, the recognition molecule further characterized as including a fluorescence label thereon and as being movable at the surface and a device for measuring a fluorescence change in response to binding between the recognition molecule and the multivalent target biomolecule.

  6. Fiber optic choline biosensor

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Cao, Xiaojian; Jia, Ke; Chai, Xueting; Lu, Hua; Lu, Zuhong

    2001-10-01

    A fiber optic fluorescence biosensor for choline is introduced in this paper. Choline is an important neurotransmitter in mammals. Due to the growing needs for on-site clinical monitoring of the choline, much effect has been devoted to develop choline biosensors. Fiber-optic fluorescence biosensors have many advantages, including miniaturization, flexibility, and lack of electrical contact and interference. The choline fiber-optic biosensor we designed implemented a bifurcated fiber to perform fluorescence measurements. The light of the blue LED is coupled into one end of the fiber as excitation and the emission spectrum from sensing film is monitored by fiber-spectrometer (S2000, Ocean Optics) through the other end of the fiber. The sensing end of the fiber is coated with Nafion film dispersed with choline oxidase and oxygen sensitive luminescent Ru(II) complex (Tris(2,2'-bipyridyl)dichlororuthenium(II), hexahydrate). Choline oxidase catalyzes the oxidation of choline to betaine and hydrogen peroxide while consuming oxygen. The fluorescence intensity of oxygen- sensitive Ru(II) are related to the choline concentration. The response of the fiber-optic sensor in choline solution is represented and discussed. The result indicates a low-cost, high-performance, portable choline biosensor.

  7. Mapping a disordered portion of the Brz2001-binding site on a plant monooxygenase, DWARF4, using a quartz-crystal microbalance biosensor-based T7 phage display.

    PubMed

    Takakusagi, Yoichi; Manita, Daisuke; Kusayanagi, Tomoe; Izaguirre-Carbonell, Jesus; Takakusagi, Kaori; Kuramochi, Kouji; Iwabata, Kazuki; Kanai, Yoshihiro; Sakaguchi, Kengo; Sugawara, Fumio

    2013-04-01

    In small-molecule/protein interaction studies, technical difficulties such as low solubility of small molecules or low abundance of protein samples often restrict the progress of research. Here, we describe a quartz-crystal microbalance (QCM) biosensor-based T7 phage display in combination use with a receptor-ligand contacts (RELIC) bioinformatics server for application in a plant Brz2001/DWARF4 system. Brz2001 is a brassinosteroid biosynthesis inhibitor in the less-soluble triazole series of compounds that targets DWARF4, a cytochrome P450 (Cyp450) monooxygenase containing heme and iron. Using a Brz2001 derivative that has higher solubility in 70% EtOH and forms a self-assembled monolayer on gold electrode, we selected 34 Brz2001-recognizing peptides from a 15-mer T7 phage-displayed random peptide library using a total of four sets of one-cycle biopanning. The RELIC/MOTIF program revealed continuous and discontinuous short motifs conserved within the 34 Brz2001-selected 15-mer peptide sequences, indicating the increase of information content for Brz2001 recognition. Furthermore, an analysis of similarity between the 34 peptides and the amino-acid sequence of DWARF4 using the RELIC/MATCH program generated a similarity plot and a cluster diagram of the amino-acid sequence. Both of these data highlighted an internally located disordered portion of a catalytic site on DWARF4, indicating that this portion is essential for Brz2001 recognition. A similar trend was also noted by an analysis using another 26 Brz2001-selected peptides, and not observed using the 27 gold electrode-recognizing control peptides, demonstrating the reproducibility and specificity of this method. Thus, this affinity-based strategy enables high-throughput detection of the small-molecule-recognizing portion on the target protein, which overcomes technical difficulties such as sample solubility or preparation that occur when conventional methods are used. PMID:23514038

  8. The larval parasitoid Microplitis croceipes oviposits in conspecific adults

    NASA Astrophysics Data System (ADS)

    Takasu, Keiji; Hoang Le, K.

    2007-03-01

    Microplitis croceipes (Hymenoptera: Braconidae) is a larval parasitoid of Helicoverpa/Heliothis spp. In the course of mass rearing of M. croceipes, we found that females oviposited in the conspecific adults in rearing cages. When 20 pairs of inexperienced females and males or of experienced females and males were reared in a cage, the males lived for 14-15 days and the females for 18-20 days on average. At their death, 37-42% of the males and 50-57% of the females contained conspecific eggs or first instar larvae in their abdominal cavity. When two of inexperienced females met on a host-infested leaf of soybean, they attempted to sting each other. Of the attacked females, 30% contained a conspecific egg laid in their abdomen. In abdominal cavity of the adults parasitized by a conspecific female, the majority of the parasitoid eggs laid disappeared within 1 day after oviposition. Only 10-30% of the parasitoid eggs laid in conspecific adults hatched 3-4 days after oviposition, but those larvae never molted to second instar. When the adults were stung by one or two conspecific females, their subsequent longevity was significantly shorter than that for the control adults. Oviposition in conspecific adults may be prevalent in other parasitic wasps that quickly oviposit without intensive host examination, and have cuticle and size of abdomen to be stung by conspeicifcs.

  9. Location dependent biases in automatic 96-well microplate readers.

    PubMed

    Harrison, R O; Hammock, B D

    1988-01-01

    Procedures performed in 96-well microplates and quantitated by automatic readers assume instruments to be precise, accurate, and free of well location dependent bias. Instrument specifications generally focus on precision and accuracy without specifically addressing biases which are dependent on well location. These biases appear to be meniscus dependent and can be demonstrated in varying degrees in automatic readers of many designs by using a reverse plate wet test, which compares repeated readings of a dye loaded plate in normal and reversed positions. This test analyzes differences between readings and is, therefore, independent of pipetting error or other experimental variables such as protein binding or immunoassay variability. Different plates increased or decreased the magnitude of observed errors but did not themselves cause the errors measured by the reverse plate wet test. Error patterns were consistent for each reader and varied widely among the 16 instruments tested. Only 4 of 16 instruments passed an existing manufacturer's specification for precision, and only one of the 16 readers tested passed a similar specification for accuracy. The severest location dependent bias was found in an instrument which exhibited excellent repeatability and consistently passed its built-in diagnostic tests. One reader with significant bias was returned to the manufacturer for routine service and calibration, but it was not demonstrably improved. The reverse plate wet test is an extremely useful diagnostic tool for quality control at all stages of instrument manufacture and use. PMID:3069835

  10. Development of a microplate reader compatible microfluidic chip for ELISA.

    PubMed

    Hou, Fenghua; Zhang, Qin; Yang, Jianping; Li, Xinchun; Yang, Xiujuan; Wang, Shuping; Cheng, Zhiyi

    2012-08-01

    We report a novel microfluidic device use for sandwich enzyme-linked immunoassay assay (ELISA). The related procedures including the introduction of reagents, dilution and distribution of samples, as well as immobilization of enzyme can be readily carried out on a poly (dimethylsiloxane) (PDMS) chip. Particularly, this microfluidic chip comprising of two distinct parallel units, and has an identical dimension as a conventional microtiter plate, which offers access to the directly quantitative detection by the microplate reader. Gradient-concentration reacting solutions at six different concentrations level generated by the microfluidic channel network are simultaneously transported to 24 reaction chambers to form enzymatic products. Alkaline phosphatase (ALP), 4-methylumbelliferyl phosphate (4-MUP) and KH(2)PO(4) are used as enzyme-substrate-inhibitor model, to demonstrate the utility of the developed microchip-based enzyme inhibitor assay. Various conditions such as the surface treatment of chip channels, fluids velocities, substrate concentration, and buffer pH are investigated. The present microfluidic device for ELISA holds several advantages, for instance frugal usage of samples and reagents, less of operating time, favorably integrated configuration, ease of manipulation, and could be explored to a variety of high throughput drug screening. PMID:22526682

  11. Microplate fecal coliform method to monitor stream water pollution.

    PubMed Central

    Maul, A; Block, J C

    1983-01-01

    A study has been carried out on the Moselle River by means of a microtechnique based on the most-probable-number method for fecal coliform enumeration. This microtechnique, in which each serial dilution of a sample is inoculated into all 96 wells of a microplate, was compared with the standard membrane filter method. It showed a marked overestimation of about 14% due, probably, to the lack of absolute specificity of the method. The high precision of the microtechnique (13%, in terms of the coefficient of variation for log most probable number) and its relative independence from the influence of bacterial density allowed the use of analysis of variance to investigate the effects of spatial and temporal bacterial heterogeneity on the estimation of coliforms. Variability among replicate samples, subsamples, handling, and analytical errors were considered as the major sources of variation in bacterial titration. Variances associated with individual components of the sampling procedure were isolated, and optimal replications of each step were determined. Temporal variation was shown to be more influential than the other three components (most probable number, subsample, sample to sample), which were approximately equal in effect. However, the incidence of sample-to-sample variability (16%, in terms of the coefficient of variation for log most probable number) caused by spatial heterogeneity of bacterial populations in the Moselle River is shown and emphasized. Consequently, we recommend that replicate samples be taken on each occasion when conducting a sampling program for a stream pollution survey. PMID:6360044

  12. Microplate spectroscopic methods for determination of the organophosphate soman.

    PubMed

    Prokofieva, Daria Stanislavovna; Voitenko, Natalia Gennadievna; Gustyleva, Lyudmila Konstantinovna; Babakov, Vladimir Nikolaevich; Savelieva, Elena Igorevna; Jenkins, Richard Owen; Goncharov, Nikolay Vasilievich

    2010-06-01

    Two microplate spectroscopic methods for determination of organophosphates, based on inhibition of acetylcholinesterase activity, have been elaborated and evaluated for determination of the chemical weapon agent soman. The principal difference between the methods is that one measures reaction substrate concentration (elaborated from Hestrin), while the other measures reaction product (elaborated from Ellman). The linear ranges of the two methods were found to be similar. Although the limit of quantification was lower for the Ellman method (110 pM), the sensitivity coefficient was in favor of the Hestrin method (1.55-fold higher). The effects of the main soman hydrolysis products were consistent for the two methods: both methylphosphonic acid and pinacolyl methylphosphonic acid did not inhibit acetylcholinesterase activity. The main components of decontaminating solutions showed differential effects: while monoethanolamine had no influence upon results obtained by either method, hydrogen peroxide interfered with the Ellman method at far lower concentrations than with the Hestrin method. In practical applications involving samples containing hydrogen peroxide, the method based on Hestrin should be regarded as much more specific for OP determination than the Ellman method. PMID:20411202

  13. Microplates based on liquid bridges between glass rods.

    PubMed

    Cheong, Brandon Huey-Ping; Lye, Jonathan Kok Keung; Backhous, Scott; Liew, Oi Wah; Ng, Tuck Wah

    2013-05-01

    Microplating that (i) does not necessitate complex or precise machinery to dispense small liquid volumes, (ii) enables fluorescent optical diagnosis, and (iii) permits simple analyte mixing mechanically is desirable. We advance here a novel approach that employs the formation of a liquid bridge held in place by capillary forces between glass rod tubes located parallel to each other. Experimental investigations made on liquid filling characteristics show conformance to theoretical notions. Analytical development showed the presence of regions of minimal uncertainty in the cross-sectional area of the liquid body arising from variations in the contact angle which permit consistent fluorescence measurements. Cyclical translation of the rods relative to each other, which cause rupture and reattachment of the liquid bridge, was found to engender good mixing. Strong linear trends were found in fluorescence signals relative to EGFP fluorophore concentration using standard and optical fiber (which offer targeted) excitation illumination. The open nature of liquid handling in the approach reported here and the positive results obtained portend the ability for development as integrated lab-on-a-chip devices. PMID:23484766

  14. Myoglobin microplate assay to evaluate prevention of protein peroxidation.

    PubMed

    Marques, Sara S; Magalhães, Luís M; Mota, Ana I P; Soares, Tânia R P; Korsak, Barbara; Reis, Salette; Segundo, Marcela A

    2015-10-10

    The current therapeutic strategies are based on the design of multifunctional drug candidates able to interact with various disease related targets. Drugs that have the ability to scavenge reactive oxygen species (ROS), beyond their main therapeutic action, may prevent the oxidative damage of biomolecules. Therefore, analytical approaches that monitor in a continuous mode the ability of drugs to counteract peroxidation of physiologically relevant biotargets are required. In the present work, a microplate spectrophotometric assay is proposed to evaluate the ability of selected cardiovascular drugs, including angiotensin-converting enzyme (ACE) inhibitors, β -blockers and statins to prevent protein peroxidation. Myoglobin, which is a heme protein, and peroxyl radicals generated from thermolysis of 2,2'-azo-bis(2-amidinopropane) dihydrochloride at 37 °C, pH 7.4 were selected as protein model and oxidative species, respectively. Myoglobin peroxidation was continuously monitored by the absorbance decrease at 409 nm and the ability of drugs to counteract protein oxidation was determined by the calculation of the area under the curve upon the myoglobin oxidation. Fluvastatin (AUC₅₀=12.5 ± 1.2 μM) and enalapril (AUC₅₀=15.2 ± 1.8 μM) showed high ability to prevent myoglobin peroxidation, providing even better efficiency than endogenous antioxidants such as reduced glutathione. Moreover, labetalol, enalapril and fluvastatin prevent the autoxidation of myoglobin, while glutathione showed a pro-oxidant effect. PMID:26093510

  15. A new, sensitive marine microalgal recombinant biosensor using luminescence monitoring for toxicity testing of antifouling biocides.

    PubMed

    Sanchez-Ferandin, Sophie; Leroy, Fanny; Bouget, François-Yves; Joux, Fabien

    2013-01-01

    In this study, we propose the use of the marine green alga Ostreococcus tauri, the smallest free-living eukaryotic cell known to date, as a new luminescent biosensor for toxicity testing in the environment. Diuron and Irgarol 1051, two antifouling biocides commonly encountered in coastal waters, were chosen to test this new biosensor along with two degradation products of diuron. The effects of various concentrations of the antifoulants on four genetic constructs of O. tauri (based on genes involved in photosynthesis, cell cycle, and circadian clock) were compared using 96-well culture microplates and a luminometer to automatically measure luminescence over 3 days. This was compared to growth inhibition of O. tauri wild type under the same conditions. Luminescence appeared to be more sensitive than growth inhibition as an indicator of toxicity. Cyclin-dependent kinase (CDKA), a protein involved in the cell cycle, fused to luciferase (CDKA-Luc) was found to be the most sensitive of the biosensors, allowing an accurate determination of the 50% effective concentration (EC(50)) after only 2 days (diuron, 5.65 ± 0.44 μg/liter; Irgarol 1015, 0.76 ± 0.10 μg/liter). The effects of the antifoulants on the CDKA-Luc biosensor were then compared to growth inhibition in natural marine phytoplankton. The effective concentrations of diuron and Irgarol 1051 were found to be similar, indicating that this biosensor would be suitable as a reliable ecotoxicological test. The advantage of this biosensor over cell growth inhibition testing is that the process can be easily automated and could provide a high-throughput laboratory approach to perform short-term toxicity tests. The ability to genetically transform and culture recombinant O. tauri gives it huge potential for screening many other toxic compounds. PMID:23144143

  16. Large-scale preparation of shape controlled SnO and improved capacitance for supercapacitors: from nanoclusters to square microplates

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Ji, Hongmei; Zhu, Feng; Chen, Zhi; Yang, Yang; Jiang, Xuefan; Pinto, João; Yang, Gang

    2013-07-01

    Here, we first provide a facile ultrasonic-assisted synthesis of SnO using SnCl2 and the organic solvent of ethanolamine (ETA). The moderate alkalinity of ETA and ultrasound play very important roles in the synthesis of SnO. After the hydrolysis of the intermediate of ETA-Sn(ii), the as-synthesized SnO nanoclusters undergo assembly, amalgamation, and preferential growth to microplates in hydrothermal treatment. The as-synthesized SnO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible absorption spectroscopy (UV-vis) and X-ray diffraction (XRD). To explore its potential applications in energy storage, SnO was fabricated into a supercapacitor electrode and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge measurements. The as-synthesized SnO exhibits remarkable pseudocapacitive activity including high specific capacitance (208.9 F g-1 at 0.1 A g-1), good rate capability (65.8 F g-1 at 40 A g-1), and excellent cycling stability (retention 119.3% after 10 000 cycles) for application in supercapacitors. The capacitive behavior of SnO with various crystal morphologies was observed by fitted EIS using an equivalent circuit. The novel synthetic route for SnO is a convenient and potential way to large-scale production of microplates which is expected to be applicable in the synthesis of other metal oxide nanoparticles.Here, we first provide a facile ultrasonic-assisted synthesis of SnO using SnCl2 and the organic solvent of ethanolamine (ETA). The moderate alkalinity of ETA and ultrasound play very important roles in the synthesis of SnO. After the hydrolysis of the intermediate of ETA-Sn(ii), the as-synthesized SnO nanoclusters undergo assembly, amalgamation, and preferential growth to microplates in hydrothermal treatment. The as-synthesized SnO was characterized by scanning

  17. Recent Trends in Biosensors

    NASA Astrophysics Data System (ADS)

    Karube, Isao

    The determination of organic compounds in foods is very important in food industries. A various compounds are contained in foods, selective determination methods are required for food processing and analysis. Electrochemical monitoring devices (biosensors) employing immobilized biocatalysts such as immobilized enzymes, organelles, microorganisms, and tissue have definite advantages. The enzyme Sensors consisted of immobilized enzymes and electrochemical devices. Enzyme sensors could be used for the determination of sugars, amino acids, organic acids, alcohols, lipids, nucleic acid derivatives, etc.. Furthermore, a multifunctional biosensor for the determination of several compounds has been developed for food processing. On the other hand, microbial sensors consisted of immobilized microorganisms and electrodes have been used for industrial and environmental analysis. Microbial sensors were applied for the determination of sugars, organic acids, alcohols, amino acids, mutagens, me thane, ammonia, and BOD. Furthermore, micro-biosensors using immobilized biocatalysts and ion sensitive field effect transistor or microelectrodes prepared by silicon fabrication technologies have been developed for medical ap. plication and food processing. This review summarizes the design and application of biosensors.

  18. Biosensors for bioprocesses

    SciTech Connect

    Van Brunt, J.

    1987-05-01

    The advent of biosensors has been touted as the marriage of the century - a marriage of microelectronics and biotechnology. But exactly what is a biosensor. Actually, the term is used interchangeably for two sometimes very different classes of devices - those that measure biological molecules and particles and those that use biomolecules as part of the sensing mechanism. The basic conceptual design of a biosensor is simple: a biological receptor is coupled to an electronic tranducer in such a way that the transducer converts biochemical activity at one end into electrical activity at the other. The biological component is usually an enzyme (for selective chemical catalysis) or an antibody (for highly selective binding), although cell membrane receptors, tissue slices, and microbial cells are used as well. The electronic component measures voltage (potentiometric), current (amperometric), light, sound, temperaure, or mass (piezoelectric). Biosensors display several unique features that make them especially attractive. They are small. They are simple to use many procedures require one step, no additional reagents, and no radioactivity. They are portable. And they are inexpensive and perfect for data processing.

  19. Large-scale preparation of shape controlled SnO and improved capacitance for supercapacitors: from nanoclusters to square microplates.

    PubMed

    Wang, Lu; Ji, Hongmei; Zhu, Feng; Chen, Zhi; Yang, Yang; Jiang, Xuefan; Pinto, João; Yang, Gang

    2013-08-21

    Here, we first provide a facile ultrasonic-assisted synthesis of SnO using SnCl2 and the organic solvent of ethanolamine (ETA). The moderate alkalinity of ETA and ultrasound play very important roles in the synthesis of SnO. After the hydrolysis of the intermediate of ETA-Sn(II), the as-synthesized SnO nanoclusters undergo assembly, amalgamation, and preferential growth to microplates in hydrothermal treatment. The as-synthesized SnO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible absorption spectroscopy (UV-vis) and X-ray diffraction (XRD). To explore its potential applications in energy storage, SnO was fabricated into a supercapacitor electrode and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge measurements. The as-synthesized SnO exhibits remarkable pseudocapacitive activity including high specific capacitance (208.9 F g(-1) at 0.1 A g(-1)), good rate capability (65.8 F g(-1) at 40 A g(-1)), and excellent cycling stability (retention 119.3% after 10,000 cycles) for application in supercapacitors. The capacitive behavior of SnO with various crystal morphologies was observed by fitted EIS using an equivalent circuit. The novel synthetic route for SnO is a convenient and potential way to large-scale production of microplates which is expected to be applicable in the synthesis of other metal oxide nanoparticles. PMID:23842544

  20. First hydrothermal active vent discovered on the Galapagos Microplate

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

    2011-12-01

    The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and hydrothermal vent community were firstly confirmed on the GSC. Lots of hydrothermal fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new hydrothermal fields were confirmed. One is named 'Precious Stone Mountain', which is the first hydrothermal field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' hydrothermal field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. Hydrothermal fluids emitting from the fissures and hydrothermal fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. Hydrothermal fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' hydrothermal field. The result indicates that seafloor materials around the hydrothermal field can be characterized into three types, such as the fresh lava, hydrothermal sediment, and altered rock.

  1. Magmatic evolution of the Easter microplate-Crough Seamount region (South East Pacific)

    USGS Publications Warehouse

    Hekinian, R.; Stoffers, P.; Akermand, D.; Binard, N.; Francheteau, Jean; Devey, C.; Garbe-Schonberg, D.

    1995-01-01

    The Easter microplate-Crough Seamount region located between 25?? S-116?? W and 25?? S-122?? W consists of a chain of seamounts forming isolated volcanoes and elongated (100-200 km in length) en echelon volcanic ridges oriented obliquely NE (N 065??), to the present day general spreading direction (N 100??) of the Pacific-Nazca plates. The extension of this seamount chain into the southwestern edge of the Easter microplate near 26??30??? S-115?? W was surveyed and sampled. The southern boundary including the Orongo fracture zone and other shallow ridges ( 0.25) MORBs which are similar in composition to other more recent basalts from the Southwest and East Rifts spreading axes of the Easter microplate. Incompatible element ratios normalized to chondrite values [(Ce/Yb)N = 1-2.5}, {(La/Sm)N = 0.4-1.2} and {(Zr/Y)N = 0.7-2.5} of the basalts are also similar to present day volcanism found in the Easter microplate. The volcanics from the Easter microplate-Crough region are unrelated to other known South Pacific intraplate magmatism (i.e. Society, Pitcairn, and Salas y Gomez Islands). Instead their range in incompatible element ratios is comparable to the submarine basalts from the recently investigated Ahu and Umu volcanic field (Easter hotspot) (Scientific Party SO80, 1993) and centered at about 80 km west of Easter Island. The oblique ridges and their associated seamounts are likely to represent ancient leaky transform faults created during the initial stage of the Easter microplate formation (??? 5 Ma). It appears that volcanic activity on seamounts overlying the oblique volcanic ridges has continued during their westward drift from the microplate as shown by the presence of relatively fresh lava observed on one of these structures, namely the first Oblique Volcanic Ridge near 25?? S-118?? W at about 160 km west of the Easter microplate West Rift. Based on a reconstruction of the Easter microplate, it is suggested that the Crough seamount (< 800 m depth) was formed

  2. Novel versatile smart phone based Microplate readers for on-site diagnoses.

    PubMed

    Fu, Qiangqiang; Wu, Ze; Li, Xiuqing; Yao, Cuize; Yu, Shiting; Xiao, Wei; Tang, Yong

    2016-07-15

    Microplate readers are important diagnostic instruments, used intensively for various readout test kits (biochemical analysis kits and ELISA kits). However, due to their expensive and non-portability, commercial microplate readers are unavailable for home testing, community and rural hospitals, especially in developing countries. In this study, to provide a field-portable, cost-effective and versatile diagnostic tool, we reported a novel smart phone based microplate reader. The basic principle of this devise relies on a smart phone's optical sensor that measures transmitted light intensities of liquid samples. To prove the validity of these devises, developed smart phone based microplate readers were applied to readout results of various analytical targets. These targets included analanine aminotransferase (ALT; limit of detection (LOD) was 17.54 U/L), alkaline phosphatase (AKP; LOD was 15.56 U/L), creatinine (LOD was 1.35μM), bovine serum albumin (BSA; LOD was 0.0041mg/mL), prostate specific antigen (PSA; LOD was 0.76pg/mL), and ractopamine (Rac; LOD was 0.31ng/mL). The developed smart phone based microplate readers are versatile, portable, and inexpensive; they are unique because of their ability to perform under circumstances where resources and expertize are limited. PMID:27019031

  3. Development of Singlet Oxygen Absorption Capacity (SOAC) Assay Method Using a Microplate Reader.

    PubMed

    Takahashi, Shingo; Iwasaki-Kino, Yuko; Aizawa, Koichi; Terao, Junji; Mukai, Kazuo

    2016-01-01

    Recently, a new assay method that can quantify the singlet oxygen absorption capacity (SOAC) of natural antioxidants and food extracts was developed. The SOAC values were measured in ethanol-chloroform-D2O (50 + 50 + 1, v/v/v) solution at 35°C using a UV-Vis spectrophotometer equipped with a six-channel cell positioner and an electron-temperature control unit. In the present study, measurement of the SOAC values was performed for eight representative carotenoids and three vegetable extracts (tomato, carrot, and red paprika) using a versatile instrument, the microplate reader. A 24-well glass microplate was used for measurements because a plastic microplate, commonly used in the laboratory, dissolves in the ethanol-chloroform-D2O solution. The SOAC values of eight carotenoids and three vegetable extracts measured using a microplate reader were in good agreement with the corresponding values measured using a UV-Vis spectrophotometer, suggesting that the microplate reader is an applicable instrument for the measurement of reliable SOAC values for general antioxidants and food extracts in solution. PMID:26822807

  4. Microplate-based method for high-throughput screening of microalgae growth potential.

    PubMed

    Van Wagenen, Jon; Holdt, Susan Løvstad; De Francisci, Davide; Valverde-Pérez, Borja; Plósz, Benedek Gy; Angelidaki, Irini

    2014-10-01

    Microalgae cultivation conditions in microplates will differ from large-scale photobioreactors in crucial parameters such as light profile, mixing and gas transfer. Hence volumetric productivity (P(v)) measurements made in microplates cannot be directly scaled up. Here we demonstrate that it is possible to use microplates to measure characteristic exponential growth rates and determine the specific growth rate light intensity dependency (μ-I curve), which is useful as the key input for several models that predict P(v). Nannochloropsis salina and Chlorella sorokiniana specific growth rates were measured by repeated batch culture in microplates supplied with continuous light at different intensities. Exponential growth unlimited by gas transfer or self-shading was observable for a period of several days using fluorescence, which is an order of magnitude more sensitive than optical density. The microplate datasets were comparable to similar datasets obtained in photobioreactors and were used an input for the Huesemann model to accurately predict P(v). PMID:25103033

  5. Scalable Production of Molybdenum Disulfide Based Biosensors.

    PubMed

    Naylor, Carl H; Kybert, Nicholas J; Schneier, Camilla; Xi, Jin; Romero, Gabriela; Saven, Jeffery G; Liu, Renyu; Johnson, A T Charlie

    2016-06-28

    We demonstrate arrays of opioid biosensors based on chemical vapor deposition grown molybdenum disulfide (MoS2) field effect transistors (FETs) coupled to a computationally redesigned, water-soluble variant of the μ-opioid receptor (MOR). By transferring dense films of monolayer MoS2 crystals onto prefabricated electrode arrays, we obtain high-quality FETs with clean surfaces that allow for reproducible protein attachment. The fabrication yield of MoS2 FETs and biosensors exceeds 95%, with an average mobility of 2.0 cm(2) V(-1) s(-1) (36 cm(2) V(-1) s(-1)) at room temperature under ambient (in vacuo). An atomic length nickel-mediated linker chemistry enables target binding events that occur very close to the MoS2 surface to maximize sensitivity. The biosensor response calibration curve for a synthetic opioid peptide known to bind to the wild-type MOR indicates binding affinity that matches values determined using traditional techniques and a limit of detection ∼3 nM (1.5 ng/mL). The combination of scalable array fabrication and rapid, precise binding readout enabled by the MoS2 transistor offers the prospect of a solid-state drug testing platform for rapid readout of the interactions between novel drugs and their intended protein targets. PMID:27227361

  6. Graphene as a signal amplifier for preparation of ultrasensitive electrochemical biosensors

    PubMed Central

    Filip, Jaroslav; Kasák, Peter; Tkac, Jan

    2016-01-01

    Early diagnostics of diseases performed with minimal money and time consumption has become achievable due to recent advances in development of biosensors. These devices use biorecognition elements for selective interaction with an analyte and signal readout is obtained via different types of transducers. Operational characteristics of biosensors have been reported to improve substantially, when a diverse range of nanomaterials was employed. This review presents construction of electrochemical biosensors based on graphene, atomically thin 2D carbon crystals, which is currently intensively studied nanomaterial. The most attractive directions of graphene applications in biosensor preparation are discussed here including novel detection and amplification schemes exploiting graphene’s unique electrochemical, physical and chemical properties. The future of graphene-based biosensors is most likely bright, but there is still a lot of work to do to fulfill high expectations. PMID:27242391

  7. Nanomaterial-Based Electrochemical Biosensors and Bioassays

    SciTech Connect

    Liu, Guodong; Mao, Xun; Gurung, Anant; Baloda, Meenu; Lin, Yuehe; He, Yuqing

    2010-08-31

    This book chapter summarizes the recent advance in nanomaterials for electrochemical biosensors and bioassays. Biofunctionalization of nanomaterials for biosensors fabrication and their biomedical applications are discussed.

  8. A direct heating model to overcome the edge effect in microplates.

    PubMed

    Lau, Chun Yat; Zahidi, Alifa Afiah Ahmad; Liew, Oi Wah; Ng, Tuck Wah

    2015-01-01

    Array-based tests in a microplate format are complicated by the regional variation in results of the outer against the inner wells of the plate. Analysis of the evaporation mechanics of sessile drops showed that evaporation rate increase with temperature was due to changes in the heat of vaporization, density and diffusion coefficient. In simulations of direct bottom heating of standard microplates, considerable heat transfer via conduction from the side walls was found to be responsible for lower temperatures in the liquid in wells close to the edge. Applying a two temperature heating mode, 304 K at the side compared to 310 K at the bottom, allowed for a more uniform temperature distribution. Transparency microplates were found to inherently possess immunity to the edge effect problem due to the presence of air between the liquid and solid wall. PMID:25289516

  9. Rigid and non-rigid micro-plates: Philippines and Myanmar-Andaman case studies

    NASA Astrophysics Data System (ADS)

    Rangin, Claude

    2016-01-01

    Generally, tectonic plates are considered as rigid. Oblique plate convergence favors the development of micro-plates along the converging boundaries. The north-south-trending Philippines archipelago (here named Philippine Mobile Belt, PMB), a few hundreds kilometers wide, is one of such complex tectonic zones. We show here that it is composed of rigid rotating crustal blocks (here called platelets). In Myanmar, the northernmost tip of the Sumatra-Andaman subduction system is another complex zone made of various crustal blocks in-between convergent plates. Yet, contrary to PMB, it sustains internal deformation with platelet buckling, altogether indicative of a non-rigid behavior. Therefore, the two case studies, Philippine Mobile Belt and Myanmar-Andaman micro-plate (MAS), illustrate the complexity of micro-plate tectonics and kinematics at convergent plate boundaries.

  10. Conducting polymer based electrochemical biosensors.

    PubMed

    Aydemir, Nihan; Malmström, Jenny; Travas-Sejdic, Jadranka

    2016-03-28

    Conducting polymer (CP)-based electrochemical biosensors have gained great attention as such biosensor platforms are easy and cost-effective to fabricate, and provide a direct electrical readout for the presence of biological analytes with high sensitivity and selectivity. CP materials themselves are both sensing elements and transducers of the biological recognition event at the same time, simplifying sensor designs. This review summarizes the advances in electrochemical biosensors based on CPs. Recognition probe immobilisation techniques, transduction mechanisms and detection of various target biomolecules have been discussed in detail. Efforts to miniaturize CP-based electrochemical biosensors and fabrication of sensor arrays are also briefly reviewed. PMID:26948182

  11. Vigorous venting and biology at Pito Seamount, Easter microplate

    NASA Astrophysics Data System (ADS)

    Naar, D. F.; Hekinian, R.; Segonzac, M.; Francheteau, J.; Armijo, R.; Cogne, J.-P.; Constantin, M.; Girardeau, J.; Hey, R. N.; Searle, R. C.

    A Nautile submersible investigation of Pito Seamount documents vigorous hydrothermal venting at 23°19.65'S, 111°38.41'W and at a depth of 2270 m. The data indicate the volcano is young and recently active, as predicted from analyses of SeaMARC II side-scan and swath bathymetry, and geophysical data. Pito Seamount lies near Pito Deep (5980 m), which marks the tip of the northwestward propagating East rift of the Easter microplate. Bathymetry surrounding Pito Seamount consists of a series of ridges and valleys with relief up to ˜4 km. The 4-km submersible-transect to the summit of Pito Seamount crossed areas of very glassy basalt with little or no sediment cover, suggesting the lava flows are very young. Most of the lava samples from Pito Seamount are depleted normal MORB (mid-ocean ridge basalt). Lava samples associated with active and dead hydrothermal vents consist of phyric and aphyric transitional and enriched MORB. Sulfides consist primarily of sphalerite and pyrite, with traces of chalcopyrite. The active hydrothermal chimney on Pito Seamount has a small, undiversified biological community similar to northern East Pacific Rise vent sites (alvinellid worms, bythograeid crabs and bythitid fishes) and western Pacific back-arc basin sites (alvinocaridid shrimps). No vestimentiferan worms were observed. Previous geophysical data, and new geochemical data and visual observations, suggest that the vigorous black smoker is a result of deep, extensive crosscutting faults formed by extensive tectonic thinning of Pito Deep, and a very robust magmatic supply being supplied from upwelling asthenosphere. Although no biological or vent fluid samples were obtained, geological and biological observations, such as the large number of inactive chimneys, old hydrothermal deposits, and starfish, as well as the occurrence of dead mollusks (gastropod and mussels), suggest a recent waning of hydrothermal activity near the summit. The speculative interpretation that Pito Seamount

  12. Carbon nanotube biosensors

    PubMed Central

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  13. Carbon Nanotube Biosensors

    NASA Astrophysics Data System (ADS)

    Tilmaciu, Carmen-Mihaela; Morris, May

    2015-10-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  14. Towards optoelectronic urea biosensors.

    PubMed

    Pokrzywnicka, Marta; Koncki, Robert; Tymecki, Łukasz

    2015-03-01

    Integration of immobilized enzymes with light-emitting diodes (LEDs) leads to the development of optoelectronic enzyme-based biosensors. In this work, urease, used as a model enzyme, immobilized in the form of an open-tubular microbioreactor or biosensing membrane that has been integrated with two red LEDs. It forms complete, fiberless, miniaturized, and extremely economic biooptoelectronic devices useful for nonstationary measurements under flow analysis conditions. Both enzyme-based biodevices, operating according to the paired emitter detector diode (PEDD) principle, allow relatively fast, highly sensitive, and well-reproducible urea detection in the millimolar range of concentrations. Potential analytical applications of the developed urea bioPEDDs have been announced. Both presented constructions will be easily adapted for the development of other optoelectronic biosensors exploring various enzyme-based schemes of biodetection. PMID:25619983

  15. Crustal Accretion and Mantle Geodynamics at Microplates: Constraints from Gravity Analysis

    NASA Astrophysics Data System (ADS)

    Ames, K.; Georgen, J. E.; Dordevic, M. M.

    2013-12-01

    Oceanic crustal accretion occurs in a variety of locations, including mid-ocean ridges and back-arc spreading centers, and in unique settings within these systems, such as plate boundary triple junctions, intra-transform spreading centers, and microplates. This study focuses on crustal accretion and mantle geodynamics at microplates. The Easter and Juan Fernandez microplates are located in the South Pacific along the Pacific, Nazca and Antarctic plate boundaries. Both microplates formed 3-5 Ma and they are currently rotating clockwise at 15 deg/Ma and 9 deg/Ma respectively (e.g., Searle et al. J. Geol. Soc. Lond. 1993). The study area also encompasses the Easter/Sala y Gomez mantle plume and the Foundation seamount chain, both of which are located close to spreading centers. We calculate mantle Bouguer anomaly (MBA) from satellite gravity measurements and shipboard soundings in order to gain a better understanding of the thermal structure of these two oceanic microplates and to quantify the effect that melting anomalies may have on their boundaries. We assume a crustal thickness of 6.0 km, a 1.7 g/cm^3 density difference at the water/crust interface, and a 0.6 g/cm^3 density difference at the crust/mantle interface. The west rift of the Easter microplate has an MBA low ranging from approximately -50 to -100 mGal, while the east rift has slightly higher MBA values ranging from roughly 10 to -50 mGal. The west rift of the Juan Fernandez microplate has a maximum MBA low of about -100 mGal with a sharp increase to -20 mGal at -35 deg S. The east rift of the Juan Fernandez microplate is characterized by more variable MBA, ranging from 0 to -140 mGal. The MBA low associated with the Easter/Sala y Gomez mantle plume has a maximum amplitude about 150 mGal. Likewise, the Foundation seamounts show a gravity low of -140 to -150 mGal. These spatial variations in gravity, as well as published isotopic data and exploratory numerical models, are used to constrain upper mantle

  16. Microplate-compatible total internal reflection fluorescence microscopy for receptor pharmacology

    NASA Astrophysics Data System (ADS)

    Chen, Minghan; Zaytseva, Natalya V.; Wu, Qi; Li, Min; Fang, Ye

    2013-05-01

    We report the use of total internal reflection fluorescence (TIRF) microscopy for analyzing receptor pharmacology and the development of a microplate-compatible TIRF imaging system. Using stably expressed green fluorescence protein tagged β2-adrenergic receptor as the reporter, we found that the activation of different receptors results in distinct kinetic signatures of the TIRF intensity of cells. These TIRF signatures closely resemble the characteristics of their respective label-free dynamic mass redistribution signals in the same cells. This suggests that TIRF in microplate can be used for profiling and screening drugs.

  17. Micro-algal biosensors.

    PubMed

    Brayner, Roberta; Couté, Alain; Livage, Jacques; Perrette, Catherine; Sicard, Clémence

    2011-08-01

    Fighting against water pollution requires the ability to detect pollutants for example herbicides or heavy metals. Micro-algae that live in marine and fresh water offer a versatile solution for the construction of novel biosensors. These photosynthetic microorganisms are very sensitive to changes in their environment, enabling the detection of traces of pollutants. Three groups of micro-algae are described in this paper: chlorophyta, cyanobacteria, and diatoms. PMID:21626188

  18. Nanobiomaterials for Electrochemical Biosensors

    NASA Astrophysics Data System (ADS)

    Pumera, M.

    2007-08-01

    I will discuss main techniques and methods which use nanoscale materials for construction of electrochemical biosensors with emphasis on methods developed by myself and my coworkers. Described approaches include carbon nanotube based electrodes relying on double wall and multiwall carbon nanotubes, novel binding materials and mass production technology; and nanoscale materials as biomolecule tracers, including gold nanoparticles for DNA detection. Specific issues related to electrochemistry of nanoscale materials will be discussed. Various applications for genomic and proteomic analysis will be described.

  19. Thermoresponsive amperometric glucose biosensor.

    PubMed

    Pinyou, Piyanut; Ruff, Adrian; Pöller, Sascha; Barwe, Stefan; Nebel, Michaela; Alburquerque, Natalia Guerrero; Wischerhoff, Erik; Laschewsky, André; Schmaderer, Sebastian; Szeponik, Jan; Plumeré, Nicolas; Schuhmann, Wolfgang

    2016-03-01

    The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(ω-ethoxytriethylenglycol methacrylate-co-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-ω-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 °C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol)methacrylate-co-butyl acrylate-co-2-(dimethylamino)ethyl methacrylate)-[Os(bpy)2(4-(((2-(2-(2-aminoethoxy)ethoxy)ethyl)amino)methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on- to an off-state without heating of the surrounding analyte solution. PMID:26702635

  20. Nano-machining of biosensor electrodes through gold nanoparticles deposition produced by femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Della Ventura, B.; Funari, R.; Anoop, K. K.; Amoruso, S.; Ausanio, G.; Gesuele, F.; Velotta, R.; Altucci, C.

    2015-06-01

    We report an application of femtosecond laser ablation to improve the sensitivity of biosensors based on a quartz crystal microbalance device. The nanoparticles produced by irradiating a gold target with 527-nm, 300-fs laser pulses, in high vacuum, are directly deposited on the quartz crystal microbalance electrode. Different gold electrodes are fabricated by varying the deposition time, thus addressing how the nanoparticles surface coverage influences the sensor response. The modified biosensor is tested by weighting immobilized IgG antibody from goat and its analyte (IgG from mouse), and the results are compared with a standard electrode. A substantial increase of biosensor sensitivity is achieved, thus demonstrating that femtosecond laser ablation and deposition is a viable physical method to improve the biosensor sensitivity by means of nanostructured electrodes.

  1. A new diamond biosensor with integrated graphitic microchannels for detecting quantal exocytic events from chromaffin cells.

    PubMed

    Picollo, Federico; Gosso, Sara; Vittone, Ettore; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2013-09-14

    An MeV ion-microbeam lithographic technique can be successfully employed for the fabrication of an all-carbon miniaturized cellular biosensor based on graphitic microchannels embedded in a single-crystal diamond matrix. The device is functionally characterized for the in vitro recording of quantal exocytic events from single chromaffin cells, with high sensitivity and signal-to-noise ratio, opening promising perspectives for the realization of monolithic all-carbon cellular biosensors. PMID:23847004

  2. Measurement of filter paper activities of cellulase with microplate-based assay

    PubMed Central

    Yu, Xiaoxiao; Liu, Yan; Cui, Yuxiao; Cheng, Qiyue; Zhang, Zaixiao; Lu, Jia Hui; Meng, Qingfan; Teng, Lirong; Ren, Xiaodong

    2015-01-01

    It is always a challenge to determine the total cellulase activity efficiently without reducing accuracy. The most common total cellulase activity assay is the filter paper assay (FPA) established by the International Union of Pure and Applied Chemistry (IUPAC). A new procedure to measure the FPA with microplate-based assay was studied in this work, which followed the main idea of IUPAC to dilute cellulase preparation to get fixed glucose release. FPAs of six cellulase preparations were determined with the microplate-based assay. It is shown that FPAs of cellulase Youtell, RCconc, R-10, Lerkam, Yishui and Sinopharm were 67.9, 46.0, 46.1, 27.4, 7.6 and 8.0 IU/ml respectively. There was no significant difference at the 95% confidence level between the FPA determined with IUPAC and the microplate-based assay. It could be concluded that the FPA could be determined by the microplate-based assay with the same accuracy and much more efficiency compared with that by IUPAC. PMID:26858572

  3. Development of LEDs-based microplate reader for bioanalytical assay measurements

    NASA Astrophysics Data System (ADS)

    Alaruri, Sami D.; Katzlinger, Michael; Schinwald, Bernhard; Kronberger, Georg; Atzler, Joseph

    2013-10-01

    The optical design for an LEDs-based microplate reader that can perform fluorescence intensity (top and bottom), absorbance, luminescence and time-resolved fluorescence measurements is described. The microplate reader is the first microplate reader in the marketplace that incorporates LEDs as excitation light sources. Absorbance measurements over the 0-3.5 optical density range for caffeine solution are presented. Additionally, fluorescence intensity readings collected at 535 and 625 nm from a green and a red RediPlateTM are reported. Furthermore, fluorescence decay lifetime measurements obtained for Eu (europium) and Sm (samarium) standard solutions using 370 nm excitation are presented. The microplate reader detection limits for the fluorescence intensity top, fluorescence intensity bottom, fluorescence polarization and time-resolved fluorescence modes are 1.5 fmol 100 µL-1 fluorescein (384-well plate), 25 fmol 100 µL-1 fluorescein (384-well plate), 5 mP at 10 nM fluorescein (black 384-well plate) and 30 amol 100 µL-1 europium solution (white 384-well plate), respectively.

  4. "Liquid Knife" to Fabricate Patterning Single-Crystalline Perovskite Microplates toward High-Performance Laser Arrays.

    PubMed

    Feng, Jiangang; Yan, Xiaoxu; Zhang, Yifan; Wang, Xuedong; Wu, Yuchen; Su, Bin; Fu, Hongbin; Jiang, Lei

    2016-05-01

    A facile and effective "liquid knife" is created by controlling the dewetting process of the liquid precursor, yielding patterning single-crystalline perovskite microplates with uniform size, precise positioning, high quality, and low lasing thresholds. The sizes and location of single-crystalline perovskite are controllable, leading to mode-tunable lasing emission and patterned lasers. PMID:27000628

  5. High-throughput measurements of the optical redox ratio using a commercial microplate reader

    NASA Astrophysics Data System (ADS)

    Cannon, Taylor M.; Shah, Amy T.; Walsh, Alex J.; Skala, Melissa C.

    2015-01-01

    There is a need for accurate, high-throughput, functional measures to gauge the efficacy of potential drugs in living cells. As an early marker of drug response in cells, cellular metabolism provides an attractive platform for high-throughput drug testing. Optical techniques can noninvasively monitor NADH and FAD, two autofluorescent metabolic coenzymes. The autofluorescent redox ratio, defined as the autofluorescence intensity of NADH divided by that of FAD, quantifies relative rates of cellular glycolysis and oxidative phosphorylation. However, current microscopy methods for redox ratio quantification are time-intensive and low-throughput, limiting their practicality in drug screening. Alternatively, high-throughput commercial microplate readers quickly measure fluorescence intensities for hundreds of wells. This study found that a commercial microplate reader can differentiate the receptor status of breast cancer cell lines (p<0.05) based on redox ratio measurements without extrinsic contrast agents. Furthermore, microplate reader redox ratio measurements resolve response (p<0.05) and lack of response (p>0.05) in cell lines that are responsive and nonresponsive, respectively, to the breast cancer drug trastuzumab. These studies indicate that the microplate readers can be used to measure the redox ratio in a high-throughput manner and are sensitive enough to detect differences in cellular metabolism that are consistent with microscopy results.

  6. Measurement of filter paper activities of cellulase with microplate-based assay.

    PubMed

    Yu, Xiaoxiao; Liu, Yan; Cui, Yuxiao; Cheng, Qiyue; Zhang, Zaixiao; Lu, Jia Hui; Meng, Qingfan; Teng, Lirong; Ren, Xiaodong

    2016-01-01

    It is always a challenge to determine the total cellulase activity efficiently without reducing accuracy. The most common total cellulase activity assay is the filter paper assay (FPA) established by the International Union of Pure and Applied Chemistry (IUPAC). A new procedure to measure the FPA with microplate-based assay was studied in this work, which followed the main idea of IUPAC to dilute cellulase preparation to get fixed glucose release. FPAs of six cellulase preparations were determined with the microplate-based assay. It is shown that FPAs of cellulase Youtell, RCconc, R-10, Lerkam, Yishui and Sinopharm were 67.9, 46.0, 46.1, 27.4, 7.6 and 8.0 IU/ml respectively. There was no significant difference at the 95% confidence level between the FPA determined with IUPAC and the microplate-based assay. It could be concluded that the FPA could be determined by the microplate-based assay with the same accuracy and much more efficiency compared with that by IUPAC. PMID:26858572

  7. Coupling the Torpedo Microplate-Receptor Binding Assay with Mass Spectrometry to Detect Cyclic Imine Neurotoxins

    PubMed Central

    Aráoz, Rómulo; Ramos, Suzanne; Pelissier, Franck; Guérineau, Vincent; Benoit, Evelyne; Vilariño, Natalia; Botana, Luis M.; Zakarian, Armen; Molgó, Jordi

    2014-01-01

    Cyclic imine neurotoxins constitute an emergent family of neurotoxins of dinoflagellate origin that are potent antagonists of nicotinic acetylcholine receptors. We developed a target-directed functional method based on the mechanism of action of competitive agonists/antagonists of nicotinic acetylcholine receptors for the detection of marine cyclic imine neurotoxins. The key step for method development was the immobilization of Torpedo electrocyte membranes rich in nicotinic acetylcholine receptors on the surface of microplate wells and the use of biotinylated-α-bungarotoxin as tracer. Cyclic imine neurotoxins competitively inhibit biotinylated-α-bungarotoxin binding to Torpedo-nicotinic acetylcholine receptors in a concentration-dependent manner. The microplate-receptor binding assay allowed rapid detection of nanomolar concentrations of cyclic imine neurotoxins directly in shellfish samples. Although highly sensitive and specific for the detection of neurotoxins targeting nicotinic acetylcholine receptors as a class, the receptor binding assay cannot identify a given analyte. To address the low selectivity of the microplate-receptor binding assay, the cyclic imine neurotoxins tightly bound to the coated Torpedo nicotinic receptor were eluted with methanol, and the chemical nature of the eluted ligands was identified by mass spectrometry. The immobilization of Torpedo electrocyte membranes on the surface of microplate wells proved to be a high-throughput format for the survey of neurotoxins targeting nicotinic acetylcholine receptors directly in shellfish matrixes with high sensitivity and reproducibility. PMID:23131021

  8. Coupling the Torpedo microplate-receptor binding assay with mass spectrometry to detect cyclic imine neurotoxins.

    PubMed

    Aráoz, Rómulo; Ramos, Suzanne; Pelissier, Franck; Guérineau, Vincent; Benoit, Evelyne; Vilariño, Natalia; Botana, Luis M; Zakarian, Armen; Molgó, Jordi

    2012-12-01

    Cyclic imine neurotoxins constitute an emergent family of neurotoxins of dinoflagellate origin that are potent antagonists of nicotinic acetylcholine receptors. We developed a target-directed functional method based on the mechanism of action of competitive agonists/antagonists of nicotinic acetylcholine receptors for the detection of marine cyclic imine neurotoxins. The key step for method development was the immobilization of Torpedo electrocyte membranes rich in nicotinic acetylcholine receptors on the surface of microplate wells and the use of biotinylated-α-bungarotoxin as tracer. Cyclic imine neurotoxins competitively inhibit biotinylated-α-bungarotoxin binding to Torpedo-nicotinic acetylcholine receptors in a concentration-dependent manner. The microplate-receptor binding assay allowed rapid detection of nanomolar concentrations of cyclic imine neurotoxins directly in shellfish samples. Although highly sensitive and specific for the detection of neurotoxins targeting nicotinic acetylcholine receptors as a class, the receptor binding assay cannot identify a given analyte. To address the low selectivity of the microplate-receptor binding assay, the cyclic imine neurotoxins tightly bound to the coated Torpedo nicotinic receptor were eluted with methanol, and the chemical nature of the eluted ligands was identified by mass spectrometry. The immobilization of Torpedo electrocyte membranes on the surface of microplate wells proved to be a high-throughput format for the survey of neurotoxins targeting nicotinic acetylcholine receptors directly in shellfish matrixes with high sensitivity and reproducibility. PMID:23131021

  9. Customizable PCR-microplate array for differential identification of multiple pathogens

    PubMed Central

    Woubit, Abdela; Yehualaeshet, Teshome; Roberts, Sherrelle; Graham, Martha; Kim, Moonil; Samuel, Temesgen

    2014-01-01

    Customizable PCR-microplate arrays were developed for the rapid identification of Francisella tularensis subsp. tularensis, Salmonella Typhi, Shigella dysenteriae, Yersinia pestis, Vibrio cholerae Escherichia coli O157:H7, Salmonella Typhimurium, Salmonella Saintpaul, Francisella tularensis subsp. novicida, Vibrio parahaemolyticus, and Yersinia pseudotuberculosis. Previously, we identified highly specific primers targeting each of the pathogens above. Here, we report the development of customizable PCR-microplate arrays for simultaneous identification of the pathogens using the primers. A mixed aliquot of genomic DNA from 38 different strains was used to validate three PCR-microplate array formats. Identical PCR conditions were used to run all the samples on the three formats. Results show specific amplifications on all the three custom plates. In a preliminary test to evaluate the sensitivity of these assays in laboratory-inoculated samples, detection limits as low as 9 cfu/g/ml S. Typhimurium were obtained from beef hot dog, and 78 cfu/ml from milk. Such microplate arrays could serve as valuable tools for initial identification or secondary confirmation of these pathogens. PMID:24215700

  10. High-Resolution Vertical Observation of Intracellular Structure Using Magnetically Responsive Microplates.

    PubMed

    Teshima, Tetsuhiko; Onoe, Hiroaki; Tottori, Soichiro; Aonuma, Hiroka; Mizutani, Takeomi; Kamiya, Koki; Ishihara, Hirotaka; Kanuka, Hirotaka; Takeuchi, Shoji

    2016-07-01

    A vertical confocal observation system capable of high-resolution observation of intracellular structure is demonstrated. The system consists of magnet-active microplates to rotate, incline, and translate single adherent cells in the applied magnetic field. Appended to conventional confocal microscopes, this system enables high-resolution cross-sectional imaging with single-molecule sensitivity in single scanning. PMID:27185344

  11. Gas sensing in microplates with optodes: influence of oxygen exchange between sample, air, and plate material.

    PubMed

    Arain, Sarina; Weiss, Svenja; Heinzle, Elmar; John, Gernot T; Krause, Christian; Klimant, Ingo

    2005-05-01

    Microplates with integrated optical oxygen sensors are a new tool to study metabolic rates and enzyme activities. Precise measurements are possible only if oxygen exchange between the sample and the environment is known. In this study we quantify gas exchange in plastic microplates. Dissolved oxygen was detected using either an oxygen-sensitive film fixed at the bottom of each well or a needle-type sensor. The diffusion of oxygen into wells sealed with different foils, paraffin oil, and paraffin wax, respectively, was quantified. Although foil covers showed the lowest oxygen permeability, they include an inevitable gas phase between sample and sealing and are difficult to manage. The use of oil was found to be critical due to the extensive shaking caused by movement of the plates during measurements in microplate readers. Thus, paraffin wax was the choice material because it avoids convection of the sample and is easy to handle. Furthermore, without shaking, significant gradients in pO2 levels within a single well of a polystyrene microplate covered with paraffin oil were detected with the needle-type sensor. Higher pO2 levels were obtained near the surface of the sample as well as near the wall of the well. A significant diffusion of oxygen through the plastic plate material was found using plates based on polystyrene. Thus, the location of a sensor element within the well has an effect on the measured pO2 level. Using a sensor film fixed on the bottom of a well or using a dissolved pO2-sensitive indicator results in pO2 offset and in apparently lower respiration rates or enzyme activities. Oxygen diffusion through a polystyrene microplate was simulated for measurements without convection--that is, for samples without oxygen diffusion through the cover and for unshaken measurements using permeable sealings. This mathematical model allows for calculation of the correct kinetic parameters. PMID:15772950

  12. New GPS Constrains on Crustal Deformation within the Puerto Rico-Virgin Islands Microplate

    NASA Astrophysics Data System (ADS)

    Solares, M. M.; Lopez, A. M.; Jansma, P. E.; Mattioli, G. S.

    2015-12-01

    Over twenty years of Global Positioning System (GPS) observations along the northeastern region of the Caribbean plate boundary zone have been used to evaluate crustal deformation in the Puerto Rico and Virgin Islands (PRVI) microplate, which generally translates westward relative to the Caribbean plate. New data from continuous GPS stations (cGPS) and re-occupied campaign GPS stations (eGPS) obtained between 2014 and 2015 allowed us to update the velocity field of the PRVI GPS Network and redefine the existing plate kinematics model of the PRVI microplate from previous measurements (Jansma et al., 2000; Jansma & Mattioli, 2005). Geodetic datasets for this epoch were processed with GIPSY/OASIS II (v.6.2) using an absolute point positioning strategy with final, precise orbits and clocks from JPL (IGS08). Results of sites velocity in the PRVI block are presented with respect to North America and Caribbean reference frames in ITRF08. The horizontal velocity components were used to calculate baseline lengths changes between selected GPS stations that span on-land faults and microplate boundaries, thus allowing quantification of internal deformation within the PRVI block. This enables us to locate zones of active deformation and faulting in order to understand how the relative motion between geological structures is accommodated. Our updated velocity field constrains intraplate deformation to 1-3 mm/yr across the PRVI microplate and active extension of 1-2 mm/yr in the Anegada passage eastern boundary. In addition, counterclockwise rotation has been observed and may be related to the deformation in southwestern Puerto Rico continuing offshore to the Muertos Trough along PRVI's southern boundary. Despite the PRVI microplate slow motion and small deformation, increasing velocities from east to west coincides with the most active microseismic zone and ongoing deformation in southwestern Puerto Rico suggesting independent motion along this segment of the PRVI block.

  13. Guided Bloch surface wave resonance for biosensor designs.

    PubMed

    Kang, Xiu-Bao; Liu, Lan-Jun; Lu, Hai; Li, Hai-Dong; Wang, Zhi-Guo

    2016-05-01

    A guided Bloch surface wave resonance (GBR) configuration is introduced for label-free biosensing. The GBR is realized by coupling the first-order diffraction of a subwavelength grating with the Bloch surface wave at the interface between a 1D photonic crystal slab and bio-solution. In addition to sustaining the Bloch surface mode, the photonic crystal provides the design freedom of simultaneously increasing the quality and decreasing the sideband transmissions of the resonance spectrum. The low sideband and high-quality features along with the large sensitivity rising from the strong overlap between the Bloch surface mode and the bio-solution make the GBR suitable for the design of biosensors. Biosensors with a high figure of merit are realized by the compact configurations. PMID:27140900

  14. Improved Biosensors for Soils

    NASA Astrophysics Data System (ADS)

    Silberg, J. J.; Masiello, C. A.; Cheng, H. Y.

    2014-12-01

    Microbes drive processes in the Earth system far exceeding their physical scale, affecting crop yields, water quality, the mobilization of toxic materials, and fundamental aspects of soil biogeochemistry. The tools of synthetic biology have the potential to significantly improve our understanding of microbial Earth system processes: for example, synthetic microbes can be be programmed to report on environmental conditions that stimulate greenhouse gas production, metal oxidation, biofilm formation, pollutant degradation, and microbe-plant symbioses. However, these tools are only rarely deployed in the lab. This research gap arises because synthetically programmed microbes typically report on their environment by producing molecules that are detected optically (e.g., fluorescent proteins). Fluorescent reporters are ideal for petri-dish applications and have fundamentally changed how we study human health, but their usefulness is quite limited in soils where detecting fluorescence is challenging. Here we describe the construction of gas-reporting biosensors, which release nonpolar gases that can be detected in the headspace of incubation experiments. These constructs can be used to probe microbial processes within soils in real-time noninvasive lab experiments. These biosensors can be combined with traditional omics-based approaches to reveal processes controlling soil microbial behavior and lead to improved environmental management decisions.

  15. Electrochemical biosensors and nanobiosensors.

    PubMed

    Hammond, Jules L; Formisano, Nello; Estrela, Pedro; Carrara, Sandro; Tkac, Jan

    2016-06-30

    Electrochemical techniques have great promise for low-cost miniaturised easy-to-use portable devices for a wide range of applications-in particular, medical diagnosis and environmental monitoring. Different techniques can be used for biosensing, with amperometric devices taking the central role due to their widespread application in glucose monitoring. In fact, glucose biosensing takes an approximately 70% share of the biosensor market due to the need for diabetic patients to monitor their sugar levels several times a day, making it an appealing commercial market.In this review, we present the basic principles of electrochemical biosensor devices. A description of the different generations of glucose sensors is used to describe in some detail the operation of amperometric sensors and how the introduction of mediators can enhance the performance of the sensors. Electrochemical impedance spectroscopy is a technique being increasingly used in devices due to its ability to detect variations in resistance and capacitance upon binding events. Novel advances in electrochemical sensors, due to the use of nanomaterials such as carbon nanotubes and graphene, are presented as well as future directions that the field is taking. PMID:27365037

  16. Multiplexed Biosensors for Mycotoxins.

    PubMed

    Maragos, Chris M

    2016-07-01

    Significant progress has been made in the development of biosensors that can be used to detect low-MW toxins produced by fungi (mycotoxins). The number of formats that have been investigated is impressive and is an indication of the importance attached to finding easy-to-use, accurate, and rapid methods for detecting these toxins in commodities and foods. This review explores the details of multiplexed biosensors based on many formats, including multiplexed immunoassays, suspension arrays, membrane-based devices (flow-through and immunochromatographic), and planar microarrays. Each assay format has its own strengths and areas that need improvement. Certain formats, such as multiplexed immunochromatographic devices, are well developed and relatively easy to use, and in some cases, commercial products are being sold. Others, such as the suspension arrays and microarrays, are laboratory-based assays that, although more complicated, are also more amenable to a larger scale of multiplexing. The diversity of such efforts and the multitude of formats under investigation suggest that multiple solutions will be found to satisfy the need for multiplexed toxin detection. PMID:27455928

  17. Electrochemical biosensors and nanobiosensors

    PubMed Central

    Hammond, Jules L.; Formisano, Nello; Carrara, Sandro; Tkac, Jan

    2016-01-01

    Electrochemical techniques have great promise for low-cost miniaturised easy-to-use portable devices for a wide range of applications–in particular, medical diagnosis and environmental monitoring. Different techniques can be used for biosensing, with amperometric devices taking the central role due to their widespread application in glucose monitoring. In fact, glucose biosensing takes an approximately 70% share of the biosensor market due to the need for diabetic patients to monitor their sugar levels several times a day, making it an appealing commercial market. In this review, we present the basic principles of electrochemical biosensor devices. A description of the different generations of glucose sensors is used to describe in some detail the operation of amperometric sensors and how the introduction of mediators can enhance the performance of the sensors. Electrochemical impedance spectroscopy is a technique being increasingly used in devices due to its ability to detect variations in resistance and capacitance upon binding events. Novel advances in electrochemical sensors, due to the use of nanomaterials such as carbon nanotubes and graphene, are presented as well as future directions that the field is taking. PMID:27365037

  18. Silver nanocube on gold microplate as a well-defined and highly active substrate for SERS detection.

    PubMed

    Xia, Xiaohu; Rycenga, Matthew; Qin, Dong; Xia, Younan

    2013-10-14

    Strong enhancement and good reproducibility in Raman signals are two major requirements for a surface-enhanced Raman scattering (SERS) substrate to be used for sensitive detection of an analyte. Here we report a new type of SERS substrate that was fabricated by depositing a Ag nanocube (AgNC) on the surface of a Au microplate (AuMP). Owing to the strong and reproducible hot spots formed at corner sites of the AgNC in proximity with the AuMP surface, the new substrate showed high sensitivity and reproducibility. Using 1,4-benzenedithiol as a probe, the SERS enhancement factor of a typical "AgNC on AuMP" substrate could reach a level as high as 4.7×10(7). In addition to the high sensitivity and reproducibility, the "AgNC on AuMP" substrate also displayed very good stability. Potential use of the "AgNC on AuMP" substrate was demonstrated by detecting crystal violet with high sensitivity. PMID:24187611

  19. Highly dispersive photonic band-gap-edge optofluidic biosensors

    NASA Astrophysics Data System (ADS)

    Xiao, S.; Mortensen, N. A.

    2006-11-01

    Highly dispersive photonic band-gap-edge optofluidic biosensors are studied theoretically. We demonstrate that these structures are strongly sensitive to the refractive index of the liquid, which is used to tune dispersion of the photonic crystal. The upper frequency band-gap edge shifts about 1.8 nm for δ n=0.002, which is quite sensitive. Results from transmission spectra agree well with those obtained from the band structure theory.

  20. Use of a parasitic wasp as a biosensor.

    PubMed

    Olson, Dawn; Rains, Glen

    2014-06-01

    Screening cargo for illicit substances is in need of rapid high-throughput inspection systems that accurately identify suspicious cargo. Here we investigate the ability of a parasitic wasp, Microplitis croceipes to detect and respond to methyl benzoate, the volatile component of cocaine, by examining their response to training concentrations, their sensitivity at low concentrations, and their ability to detect methyl benzoate when two concealment substances (green tea and ground coffee) are added to the testing arena. Utilizing classical associative learning techniques with sucrose as reward, we found that M. croceipes learns individual concentrations of methyl benzoate, and they can generalize this learning to concentrations 100× lower than the training concentration. Their sensitivity to methyl benzoate is very low at an estimated 3 ppb. They are also able to detect methyl benzoate when covered completely by green tea, but were not able to detect methyl benzoate when covered completely by coffee grounds. Habituation to the tea and coffee odors prior to testing improves their responses, resulting in effective detection of methyl benzoate covered by the coffee grounds. With the aid of the portable device called 'the wasp hound', the wasps appear to have potential to be effective on-site biosensors for the detection of cocaine. PMID:25587415

  1. Biosensor commercialization strategy - a theoretical approach.

    PubMed

    Lin, Chin-Tsai; Wang, Su-Man

    2005-01-01

    Biosensors are analytical devices, which use biological interactions to provide either qualitative or quantitative results. They are extensively employed in many fields such as clinical diagnosis and biomedicine, military applications, anti-terrorism, farm, garden and veterinary analysis, process control, fermentation control and analysis, pharmaceutical and drug analysis, food and drink production and analysis, pollution control and monitoring, microbiology, bacterial and viral analysis, mining, and industrial and toxic gases. The biosensor market has significantly increased and will be mushrooming in the next decade. The total biosensor market is estimated to be 10.8 billion dollars by 2007. The emerging biosensor market presents both opportunities and obstacles to start-up biosensor entrepreneurs. The major challenge and threat for these entrepreneurs is how to predict the biosensor market and how to convert promising biosensor technology into commercialized biosensors. By adopting a simple commercialization strategy framework, we identify two key elements of biosensor commercialization strategy: excludability and complementary asset. We further divide biosensor commercialization environments into four distinct sub-environments: the Attacker's Advantage, Reputation-Based Idea Trading, Greenfield Competition and Ideas Factories. This paper explains how the interaction between these two key elements shapes biosensor commercialization strategy and biosensor industry dynamics. This paper also discusses alternative commercialization strategies for each specific commercialization environment and how to choose from these alternatives. The analysis of this study further provides a good reference for start-up biosensor entrepreneurs to formulate effective biosensor commercialization strategy. PMID:15574353

  2. Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity

    PubMed Central

    Frąc, Magdalena; Gryta, Agata; Oszust, Karolina; Kotowicz, Natalia

    2016-01-01

    The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (BiologTM) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole

  3. Wandering terranes in southern Alaska: The Aleutia Microplate and implications for the Bering Sea

    NASA Astrophysics Data System (ADS)

    Marlow, Michael S.; Cooper, Alan K.

    1983-04-01

    Paleomagnetic and geological data suggest that much of southern Alaska is a collage of tectonostratigraphic terranes which originated in Mesozoic time at paleolatitudes far south of their present position. The time of `docking' of the terranes against cratonic Alaska is critical to defining their amalgamated size and extent during their northward motion as well as their role in the evolution of the Bering Sea. One of the largest of the tectonostratigraphic terranes, the Peninsular terrane of south central and southwestern Alaska, extends offshore along the outer Bering Sea continental margin (Beringia). Paleomagnetic data suggest that this terrane has moved northward through all of Cenozoic time, but geologic data imply that the terrane had accreted to Alaska by the end of the Mesozoic. In early Cenozoic time the eastern part of the Aleutian arc appears to have been superimposed on the Peninsular terrane, and postulated northward Cenozoic motion of the terrane would therefore have required northward motion of the arc. Two accretion models, based on docking times for terranes in Alaska, are proposed, and they illustrate that large areas of the abyssal Bering Sea, the Alaska Peninsula, the Aleutian arc, and the Beringian continental margin may be part of a superterrane or microplate called Aleutia (microplate as defined by Beck et al. (1980), i.e., a microplate is a displaced segment of lithosphere that has crustal roots, whereas a superterrane is an amalgamation of terranes which may or may not be rootless). Model A implies that the Aleutian arc developed in situ on the southern edge of Aleutia after the microplate had docked. In model B, the final docking time of the Peninsular terrane is late Cenozoic, which implies that the Aleutia microplate encompasses a mammoth area that includes parts of southern Alaska, the Alaska Peninsula, the southern Beringian margin, the abyssal Bering Sea (Kula plate), and the Aleutian arc. If model A is correct, the docking time of

  4. Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity.

    PubMed

    Frąc, Magdalena; Gryta, Agata; Oszust, Karolina; Kotowicz, Natalia

    2016-01-01

    The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (Biolog(TM)) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole

  5. Sensors and Biosensors for the Determination of Small Molecule Biological Toxins

    PubMed Central

    Wang, Xiang-Hong; Wang, Shuo

    2008-01-01

    The following review of sensors and biosensors focuses on the determination of commonly studied small molecule biological toxins, including mycotoxins and small molecule neurotoxins. Because of the high toxicity of small molecule toxins, an effective analysis technique for determining their toxicity is indispensable. Sensors and biosensors have emerged as sensitive and rapid techniques for toxicity analysis in the past decade. Several different sensors for the determination of mycotoxins and other small molecule neurotoxins have been reported in the literature, and many of these sensors such as tissue biosensors, enzyme sensors, optical immunosensors, electrochemical sensors, quartz crystal sensors, and surface plasmon resonance biosensors are reviewed in this paper. Sensors are a practical and convenient monitoring tool in the area of routine analysis, and their specificity, sensitivity, reproducibility and analysis stability should all be improved in future work. In addition, accuracy field portable sensing devices and multiplexing analysis devices will be important requirement for the future.

  6. The electrophotonic silicon biosensor.

    PubMed

    Juan-Colás, José; Parkin, Alison; Dunn, Katherine E; Scullion, Mark G; Krauss, Thomas F; Johnson, Steven D

    2016-01-01

    The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale. PMID:27624590

  7. Noninvasive biosensor for hypoglycemia

    NASA Astrophysics Data System (ADS)

    Varadan, Vijay K.; Whitchurch, Ashwin K.; Sarukesi, Karunakaran

    2003-01-01

    Hypoglycemia-abnormal decrease in blood sugar- is a major obstacle in the management of diabetes and prevention of long-term complications, and it may impose serious effects on the brain, including impairment of memory and other cognitive functions. This is especially a concern in early childhood years when the nervous system is still developing. Hypoglycemic unawareness (in which the body"s normal ability to signal low blood sugar doesn"t work and an oncoming low blood sugar episode proceeds undetected) is a particularly frightening problem for many people with diabetes. Researchers have now uncovered evidence that repeated bouts of insulin-induced hypoglycemia can harm the brain over time, causing confusion, abnormal behavior, loss of consciousness, and seizures. Extreme cases have resulted in coma and death. In this paper, a non-invasive biosensor in a wrist watch along with a wireless data downloading system is proposed.

  8. Glycan and lectin biosensors

    PubMed Central

    Belický, Štefan; Katrlík, Jaroslav

    2016-01-01

    A short description about the importance of glycan biorecognition in physiological (blood cell type) and pathological processes (infections by human and avian influenza viruses) is provided in this review. Glycans are described as much better information storage media, compared to proteins or DNA, due to the extensive variability of glycan structures. Techniques able to detect an exact glycan structure are briefly discussed with the main focus on the application of lectins (glycan-recognising proteins) in the specific analysis of glycans still attached to proteins or cells/viruses. Optical, electrochemical, piezoelectric and micromechanical biosensors with immobilised lectins or glycans able to detect a wide range of analytes including whole cells/viruses are also discussed. PMID:27365034

  9. Glycan and lectin biosensors.

    PubMed

    Belický, Štefan; Katrlík, Jaroslav; Tkáč, Ján

    2016-06-30

    A short description about the importance of glycan biorecognition in physiological (blood cell type) and pathological processes (infections by human and avian influenza viruses) is provided in this review. Glycans are described as much better information storage media, compared to proteins or DNA, due to the extensive variability of glycan structures. Techniques able to detect an exact glycan structure are briefly discussed with the main focus on the application of lectins (glycan-recognising proteins) in the specific analysis of glycans still attached to proteins or cells/viruses. Optical, electrochemical, piezoelectric and micromechanical biosensors with immobilised lectins or glycans able to detect a wide range of analytes including whole cells/viruses are also discussed. PMID:27365034

  10. DNA nanotechnology-enabled biosensors.

    PubMed

    Chao, Jie; Zhu, Dan; Zhang, Yinan; Wang, Lianhui; Fan, Chunhai

    2016-02-15

    Biosensors employ biological molecules to recognize the target and utilize output elements which can translate the biorecognition event into electrical, optical or mass-sensitive signals to determine the quantities of the target. DNA-based biosensors, as a sub-field to biosensor, utilize DNA strands with short oligonucleotides as probes for target recognition. Although DNA-based biosensors have offered a promising alternative for fast, simple and cheap detection of target molecules, there still exist key challenges including poor stability and reproducibility that hinder their competition with the current gold standard for DNA assays. By exploiting the self-recognition properties of DNA molecules, researchers have dedicated to make versatile DNA nanostructures in a highly rigid, controllable and functionalized manner, which offers unprecedented opportunities for developing DNA-based biosensors. In this review, we will briefly introduce the recent advances on design and fabrication of static and dynamic DNA nanostructures, and summarize their applications for fabrication and functionalization of DNA-based biosensors. PMID:26212206

  11. Improvement of up-converting phosphor technology-based biosensor

    NASA Astrophysics Data System (ADS)

    Xie, Chengke; Huang, Lihua; Zhang, Youbao; Guo, Xiaoxian; Qu, Jianfeng; Huang, Huijie

    2008-12-01

    A novel biosensor based on up-converting phosphor technology (UPT) was developed several years ago. It is a kind of optical biosensor using up-converting phosphor (UCP) particles as the biological marker. From then on, some improvements have been made for this UPT-based biosensor. The primary aspects of the improvement lie in the control system. On one hand, the hardware of the control system has been optimized, including replacing two single chip microcomputers (SCM) with only one, the optimal design of the keyboard interface circuit and the liquid crystal module (LCM) control circuit et al.. These result in lower power consumption and higher reliability. On the other hand, a novel signal processing algorithm is proposed in this paper, which can improve the automation and operating simplicity of the UPT-based biosensor. It has proved to have high sensitivity (~ng/ml), high stability and good repeatability (CV<5%), which is better than the former system. It can meet the need of some various applications such as rapid immunoassay, chemical and biological detection and so on.

  12. A Fast Optical Method for the Determination of Liquid Levels in Microplates

    PubMed Central

    Thurow, Kerstin; Stoll, Norbert; Ritterbusch, Kai

    2011-01-01

    Parallel liquid handling systems are widely used in different applications of life sciences. In order to avoid false positive or negative results which lead to higher costs due to the replication of the experiments it is necessary to monitor the process and success of liquid delivery. An easy method for the determination of the liquid levels in microplates has been developed and evaluated. The optical method bases on the measurement of the liquid level using CCD cameras followed by special algorithms for the evaluation and visualization of the measured data. The proposed method was tested in changing environmental lighting for two different liquids. These tests confirm our approach towards optical liquid level determination for smallest volumes in microplates and also show the challenges regarding environmental lighting and different physical properties of fluids. PMID:21747734

  13. Analysis of Aerobic Respiration in Intact Skeletal Muscle Tissue by Microplate-Based Respirometry.

    PubMed

    Shintaku, Jonathan; Guttridge, Denis C

    2016-01-01

    Mitochondrial function is a key component of skeletal muscle health, and its dysfunction has been associated with a wide variety of diseases. Microplate-based respirometry measures aerobic respiration of live cells through extracellular changes in oxygen concentration. Here, we describe a methodology to measure aerobic respiration of intact murine skeletal muscle tissue. The tissues are not cultured, permeabilized, or enzymatically dissociated to single fibers, so there is minimal experimental manipulation affecting the samples prior to acquiring measurements. PMID:27492183

  14. High-throughput microplate technique for enzymatic hydrolysis of lignocellulosic biomass.

    PubMed

    Chundawat, Shishir P S; Balan, Venkatesh; Dale, Bruce E

    2008-04-15

    Several factors will influence the viability of a biochemical platform for manufacturing lignocellulosic based fuels and chemicals, for example, genetically engineering energy crops, reducing pre-treatment severity, and minimizing enzyme loading. Past research on biomass conversion has focused largely on acid based pre-treatment technologies that fractionate lignin and hemicellulose from cellulose. However, for alkaline based (e.g., AFEX) and other lower severity pre-treatments it becomes critical to co-hydrolyze cellulose and hemicellulose using an optimized enzyme cocktail. Lignocellulosics are appropriate substrates to assess hydrolytic activity of enzyme mixtures compared to conventional unrealistic substrates (e.g., filter paper, chromogenic, and fluorigenic compounds) for studying synergistic hydrolysis. However, there are few, if any, high-throughput lignocellulosic digestibility analytical platforms for optimizing biomass conversion. The 96-well Biomass Conversion Research Lab (BCRL) microplate method is a high-throughput assay to study digestibility of lignocellulosic biomass as a function of biomass composition, pre-treatment severity, and enzyme composition. The most suitable method for delivering milled biomass to the microplate was through multi-pipetting slurry suspensions. A rapid bio-enzymatic, spectrophotometric assay was used to determine fermentable sugars. The entire procedure was automated using a robotic pipetting workstation. Several parameters that affect hydrolysis in the microplate were studied and optimized (i.e., particle size reduction, slurry solids concentration, glucan loading, mass transfer issues, and time period for hydrolysis). The microplate method was optimized for crystalline cellulose (Avicel) and ammonia fiber expansion (AFEX) pre-treated corn stover. PMID:18306256

  15. Carbon-coated lithium titanium phosphate nanoporous microplates with superior electrochemical performance

    NASA Astrophysics Data System (ADS)

    Huang, Zhifeng; Liu, Li; Zhou, Qian; Tan, Jinli; Yan, Zichao; Xia, Dongdong; Shu, Hongbo; Yang, Xiukang; Wang, Xianyou

    2015-10-01

    In this study, we report a facile method to synthesize carbon-coated LiTi2(PO4)3 nanoporous microplates (LTP/C MPs) using ethylenediamine as the chelating agent and carbon source. The as-prepared LTP/C MPs with thickness of 0.4 μm consist of interconnected nanosized particles embedded in nano-thickness carbon layer and well-dispersed nanopores. The carbon layer significantly improves the electrochemical performance of LiTi2(PO4)3 microplates. LTP/C MPs deliver a reversible capacity of 121 mAh g-1 at 0.2C (1C = 138 mAh g-1) and show a remarkable capacity retention of 94.2% over 100 cycles when matched with Li metal counter electrode. It also presents excellent electrochemical properties as anode material for aqueous rechargeable lithium batteries (ARLBs). LTP/C MPs//LiMn2O4 ARLB shows a high discharge capacity of 76 mAh g-1 at 20 mA g-1 and superior rate capability. The results suggest a practical stratagem to develop a novel composite in which the carbon is coated with LiTi2(PO4)3 nanoporous microplates, which can become one of the promising electrode materials for both non-aqueous and aqueous lithium ion batteries.

  16. Using Isolated Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High throughput Microplate Respiratory Measurements

    PubMed Central

    Boutagy, Nabil E.; Rogers, George W.; Pyne, Emily S.; Ali, Mostafa M.; Hulver, Matthew W.; Frisard, Madlyn I.

    2015-01-01

    Skeletal muscle mitochondria play a specific role in many disease pathologies. As such, the measurement of oxygen consumption as an indicator of mitochondrial function in this tissue has become more prevalent. Although many technologies and assays exist that measure mitochondrial respiratory pathways in a variety of cells, tissue and species, there is currently a void in the literature in regards to the compilation of these assays using isolated mitochondria from mouse skeletal muscle for use in microplate based technologies. Importantly, the use of microplate based respirometric assays is growing among mitochondrial biologists as it allows for high throughput measurements using minimal quantities of isolated mitochondria. Therefore, a collection of microplate based respirometric assays were developed that are able to assess mechanistic changes/adaptations in oxygen consumption in a commonly used animal model. The methods presented herein provide step-by-step instructions to perform these assays with an optimal amount of mitochondrial protein and reagents, and high precision as evidenced by the minimal variance across the dynamic range of each assay. PMID:26555567

  17. Platelet aggregation inhibitors from Philippine marine invertebrate samples screened in a new microplate assay.

    PubMed

    Pimentel, Sheila Marie V; Bojo, Zenaida P; Roberto, Amy V D; Lazaro, Jose Enrico H; Mangalindan, Gina C; Florentino, Leila M; Lim-Navarro, Pilar; Tasdemir, Deniz; Ireland, Chris M; Concepcion, Gisela P

    2003-01-01

    A new microplate assay for Ca(2+)-induced platelet aggregation as detected by Giemsa dye was used to screen marine invertebrate samples from the Philippines for inhibitors of human platelet aggregation. Out of 261 crude methanol extracts of marine sponges and tunicates, 25 inhibited aggregation at 2 mg/ml. Inhibition of agonist-induced aggregation in an aggregometer was used to confirm results of the microplate assay and to determine the specific mode of inhibition of 2 samples. The marine sponge Xestospongia sp. yielded a xestospongin/araguspongine-type molecule that inhibited collagen-induced aggregation by 87% at 2 micro g/ml, and epinephrine-induced aggregation by 78% at 20 micro g/ml, while the marine sponge Aplysina sp. yielded 5,6-dibromotryptamine, which inhibited epinephrine-induced aggregation by 51% at 20 micro g/ml. In this study we have found that the microplate assay is a simple, inexpensive, yet useful preliminary tool to qualitatively screen a large number of marine samples for antiplatelet aggregation activity. PMID:14719168

  18. Influence of acoustic streaming on ultrasonic particle manipulation in a 100-well ring-transducer microplate

    NASA Astrophysics Data System (ADS)

    Ohlin, Mathias; Christakou, Athanasia E.; Frisk, Thomas; Önfelt, Björn; Wiklund, Martin

    2013-03-01

    We characterize and quantify the performance of ultrasonic particle aggregation and positioning in a 100-well microplate. We analyze the result when operating a planar ultrasonic ring transducer at different single actuation frequencies in the range 2.20-2.40 MHz, and compare with the result obtained from different schemes of frequency-modulated actuation. Compared to our previously used wedge transducer design, the ring transducer has a larger contact area facing the microplate, resulting in lower temperature increase for a given actuation voltage. Furthermore, we analyze the dynamics of acoustic streaming occurring simultaneously with the particle trapping in the wells of the microplate, and we define an adaptive ultrasonic actuation scheme for optimizing both efficiency and robustness of the method. The device is designed as a tool for ultrasound-mediated cell aggregation and positioning. This is a method for high-resolution optical characterization of time-dependent cellular processes at the level of single cells. In this paper, we demonstrate how to operate our device in order to optimize the scanning time of 3D confocal microscopy with the aim to perform high-resolution time-lapse imaging of cells or cell-cell interactions in a highly parallel manner.

  19. NANOSCALE BIOSENSORS IN ECOSYSTEM EXPOSURE RESEARCH

    EPA Science Inventory

    This powerpoint presentation presented information on nanoscale biosensors in ecosystem exposure research. The outline of the presentation is as follows: nanomaterials environmental exposure research; US agencies involved in nanosensor research; nanoscale LEDs in biosensors; nano...

  20. BIOSENSORS FOR ENVIRONMENTAL MONITORING: A REGULATORY PERSPECTIVE

    EPA Science Inventory

    Biosensors show the potential to complement laboratory-based analytical methods for environmental applications. Although biosensors for potential environmental-monitoring applications have been reported for a wide range of environmental pollutants, from a regulatory perspective, ...

  1. Block rotation and continental extension in Afar: A comparison to oceanic microplate systems

    NASA Astrophysics Data System (ADS)

    Acton, Gary D.; Stein, Seth; Engeln, Joseph F.

    1991-06-01

    The reorganization of oceanic spreading centers separating major plates often appears to occur by a process in which discrete microplates form and evolve by rift propagation. To see whether such microplate behavior has implications for continental rifting, we investigate the application of a microplate model to the Afar region at the Nubia-Somalia-Arabia triple junction. Studies of marine magnetic anomalies, volcanic ages, bathymetry, and seismicity suggest that the westward propagating Gulf of Aden spreading center has propagated into eastern Afar within the past 2 m.y., causing rifting and extension within the continent. We derive constraints on the extension history from the geometry and timing of rift formation and from paleomagnetic data indicating that Pliocene to Pleistocene age rocks have undergone a clockwise rotation of ˜11°. We suggest that the history of rifting, the rotation, and several other features of the regional geology can be described by combining features of an oceanic microplate model and the concept of rift localization previously proposed for Afar. In this scenario, motion occurring on several rifts within an extensional zone preceding the propagating spreading center is gradually transferred to a single rift. While motion is transferred, the overlap region between the growing and dying rifts acts as one or more microplates or blocks that rotate relative to the surrounding major plates. The rifting history and rotations in eastern Afar are thus related to the rift propagation and localization that occurs as the plate boundary evolves. Provided the constraints we use are appropriate, our model better describes the regional kinematics than alternative block models including one based on "bookshelf" faulting. If the tectonics of Afar are typical for continental breakup, they have interesting implications for the geometry of passive margins. In particular, asymmetric rifted margins can be produced if the final location of the rift axis is not

  2. Biosensor for metal analysis and speciation

    DOEpatents

    Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

    2007-01-30

    A biosensor for metal analysis and speciation is disclosed. The biosensor comprises an electron carrier immobilized to a surface of an electrode and a layer of an immobilized enzyme adjacent to the electrode. The immobilized enzyme comprises an enzyme having biological activity inhibited by a metal to be detected by the biosensor.

  3. Porous silicon biosensor: current status.

    PubMed

    Dhanekar, Saakshi; Jain, Swati

    2013-03-15

    Biosensing technologies cater to modern day diagnostics and point of care multi-specialty clinics, hospitals and laboratories. Biosensors aggregate the sensitivity of detection methodologies and constitutional selectivity of biomolecules. Endeavors to develop highly sensitive, fast, stable and low cost biosensors have been made possible by extensive and arduous research. Immense research work is going on for detection of molecules using various materials as immobilization substrate and sensing elements. Amongst materials being used as bio-sensing substrates, nano-porous silicon (PS) has amassed attention and gained popularity in recent years. It has captivating and tunable features like ease of fabrication, special optico-physico properties, tailored morphological structure and versatile surface chemistry enhancing its prospects as transducer for fabricating biosensors. The present review describes the fabrication of PS and its biosensing capabilities for detection of various analytes including, but not limited to, glucose, DNA, antibodies, bacteria and viruses. Attention has been consecrated on the various methodologies such as electrical, electrochemical, optical and label free techniques along with the performances of these biosensors. It concludes with some future prospects and challenges of PS based biosensors. PMID:23122704

  4. DNA biosensors that reason.

    PubMed

    Sainz de Murieta, Iñaki; Rodríguez-Patón, Alfonso

    2012-08-01

    Despite the many designs of devices operating with the DNA strand displacement, surprisingly none is explicitly devoted to the implementation of logical deductions. The present article introduces a new model of biosensor device that uses nucleic acid strands to encode simple rules such as "IF DNA_strand(1) is present THEN disease(A)" or "IF DNA_strand(1) AND DNA_strand(2) are present THEN disease(B)". Taking advantage of the strand displacement operation, our model makes these simple rules interact with input signals (either DNA or any type of RNA) to generate an output signal (in the form of nucleotide strands). This output signal represents a diagnosis, which either can be measured using FRET techniques, cascaded as the input of another logical deduction with different rules, or even be a drug that is administered in response to a set of symptoms. The encoding introduces an implicit error cancellation mechanism, which increases the system scalability enabling longer inference cascades with a bounded and controllable signal-noise relation. It also allows the same rule to be used in forward inference or backward inference, providing the option of validly outputting negated propositions (e.g. "diagnosis A excluded"). The models presented in this paper can be used to implement smart logical DNA devices that perform genetic diagnosis in vitro. PMID:22406690

  5. Plants as Environmental Biosensors

    PubMed Central

    Ranatunga, Don Rufus A

    2006-01-01

    Plants are continuously exposed to a wide variety of perturbations including variation of temperature and/or light, mechanical forces, gravity, air and soil pollution, drought, deficiency or surplus of nutrients, attacks by insects and pathogens, etc., and hence, it is essential for all plants to have survival sensory mechanisms against such perturbations. Consequently, plants generate various types of intracellular and intercellular electrical signals mostly in the form of action and variation potentials in response to these environmental changes. However, over a long period, only certain plants with rapid and highly noticeable responses for environmental stresses have received much attention from plant scientists. Of particular interest to our recent studies on ultra fast action potential measurements in green plants, we discuss in this review the evidence supporting the foundation for utilizing green plants as fast biosensors for molecular recognition of the direction of light, monitoring the environment, and detecting the insect attacks as well as the effects of pesticides, defoliants, uncouplers, and heavy metal pollutants. PMID:19521490

  6. Biosensors for termite control

    NASA Astrophysics Data System (ADS)

    Farkhanda, M.

    2013-12-01

    Termites are major urban pests in Pakistan and cause damage to wooden structures and buildings. Termite management has two parts: prevention and control. The most difficult part of termite control is termite detection as most of them are subterranean in Pakistan and have tunneling habit.Throughout the world, chemical termiticides are going to be replaced by baits, microwave and sensor technology. Termite species are distinct biologically and have specific foraging behaviors. Termite Detection Radar, Moisture meter and Remote Thermal Sensor with Laser are available throughout the world. These can detect termites underground and use fewer chemicals than traditional methods. For wooden buildings, a termite sensor and an intrusion detection system for detecting termites are designed. A pair of electrodes is disposed inside the container. A pair of terminals is connected to these electrodes, these extend outside the container. Termites are detected by a change of conductivity between the electrodes, when termites are detected a warning device generates a warning signal. In Pakistan, there is dire need to develop such biosensoring devices locally, then apply control methods that would save money and protect the environment.

  7. Fluidics cube for biosensor miniaturization

    NASA Technical Reports Server (NTRS)

    Dodson, J. M.; Feldstein, M. J.; Leatzow, D. M.; Flack, L. K.; Golden, J. P.; Ligler, F. S.

    2001-01-01

    To create a small, portable, fully automated biosensor, a compact means of fluid handling is required. We designed, manufactured, and tested a "fluidics cube" for such a purpose. This cube, made of thermoplastic, contains reservoirs and channels for liquid samples and reagents and operates without the use of any internal valves or meters; it is a passive fluid circuit that relies on pressure relief vents to control fluid movement. We demonstrate the ability of pressure relief vents to control fluid movement and show how to simply manufacture or modify the cube. Combined with the planar array biosensor developed at the Naval Research Laboratory, it brings us one step closer to realizing our goal of a handheld biosensor capable of analyzing multiple samples for multiple analytes.

  8. Modelling a Peroxidase-based Optical Biosensor

    PubMed Central

    Baronas, Romas; Gaidamauskaite, Evelina; Kulys, Juozas

    2007-01-01

    The response of a peroxidase-based optical biosensor was modelled digitally. A mathematical model of the optical biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments, an enzyme layer and an outer diffusion layer. The digital simulation was carried out using finite difference technique. The influence of the substrate concentration as well as of the thickness of both the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially at low concentrations of the peroxidase and of the hydrogen peroxide.

  9. Faulting and strain partitioning in Jamaica from GPS and structural data: Implications for Gonave and Hispaniola microplate kinematics, northern Caribbean

    NASA Astrophysics Data System (ADS)

    Benford, Bryn

    A series of small microplates separate the Caribbean and North America plates in the northern Caribbean. My dissertation focuses on understanding the structural evolution and neotectonic deformation of Jamaica, and how it relates to the overall microplates and tectonics of the northern Caribbean. Jamaica, which lies along the same seismically active plate boundary as Haiti, has had twelve earthquakes with Modified Mercalli intensities of VII to X since 1667. However, remarkably little is known about which faults presently constitute the most significant seismic hazards. This research provides insight into tectonic processes and facilitates mitigation of geological hazards in the region. Two chapters focus on characterizing deformation in Jamaica through modeling GPS velocities and through field mapping. The best-fitting models based on GPS velocities place most strike-slip motion on faults in central Jamaica and suggest that faults in northern Jamaica have minimal motion. I estimate 4--5 mm yr-1 of slip for faults near the capital city of Kingston of southeastern Jamaica, implying significant seismic hazard. Field mapping combined with present-day topography, focal mechanisms, geology, gravity, and well and borehole data indicate that east-west contraction is accommodated by reactivated, NNW-striking reverse faults, which are bound by E-striking strike-slip faults in southern Jamaica. The other two chapters of my thesis focuses on understanding the behavior of the microplates along the Caribbean-North America plate boundary: I model GPS velocities and use shear-wave splitting to understand the crustal and mantle behaviors, respectively of the microplates. The GPS data require an independently moving Hispaniola microplate between the Mona Passage and a likely diffuse boundary just west of or within western Hispaniola. The new microplate angular velocities predict 6.8+/-1.0 mm yr-1 of left-lateral slip and 5.7+/-1 mm yr-1 of convergent motion surrounding the

  10. Biosensors in Clinical Practice: Focus on Oncohematology

    PubMed Central

    Fracchiolla, Nicola S.; Artuso, Silvia; Cortelezzi, Agostino

    2013-01-01

    Biosensors are devices that are capable of detecting specific biological analytes and converting their presence or concentration into some electrical, thermal, optical or other signal that can be easily analysed. The first biosensor was designed by Clark and Lyons in 1962 as a means of measuring glucose. Since then, much progress has been made and the applications of biosensors are today potentially boundless. This review is limited to their clinical applications, particularly in the field of oncohematology. Biosensors have recently been developed in order to improve the diagnosis and treatment of patients affected by hematological malignancies, such as the biosensor for assessing the in vitro pre-treatment efficacy of cytarabine in acute myeloid leukemia, and the fluorescence resonance energy transfer-based biosensor for assessing the efficacy of imatinib in chronic myeloid leukemia. The review also considers the challenges and future perspectives of biosensors in clinical practice. PMID:23673681

  11. Biosensors and their applications – A review

    PubMed Central

    Mehrotra, Parikha

    2016-01-01

    The various types of biosensors such as enzyme-based, tissue-based, immunosensors, DNA biosensors, thermal and piezoelectric biosensors have been deliberated here to highlight their indispensable applications in multitudinous fields. Some of the popular fields implementing the use of biosensors are food industry to keep a check on its quality and safety, to help distinguish between the natural and artificial; in the fermentation industry and in the saccharification process to detect precise glucose concentrations; in metabolic engineering to enable in vivo monitoring of cellular metabolism. Biosensors and their role in medical science including early stage detection of human interleukin-10 causing heart diseases, rapid detection of human papilloma virus, etc. are important aspects. Fluorescent biosensors play a vital role in drug discovery and in cancer. Biosensor applications are prevalent in the plant biology sector to find out the missing links required in metabolic processes. Other applications are involved in defence, clinical sector, and for marine applications. PMID:27195214

  12. Biosensors and their applications - A review.

    PubMed

    Mehrotra, Parikha

    2016-01-01

    The various types of biosensors such as enzyme-based, tissue-based, immunosensors, DNA biosensors, thermal and piezoelectric biosensors have been deliberated here to highlight their indispensable applications in multitudinous fields. Some of the popular fields implementing the use of biosensors are food industry to keep a check on its quality and safety, to help distinguish between the natural and artificial; in the fermentation industry and in the saccharification process to detect precise glucose concentrations; in metabolic engineering to enable in vivo monitoring of cellular metabolism. Biosensors and their role in medical science including early stage detection of human interleukin-10 causing heart diseases, rapid detection of human papilloma virus, etc. are important aspects. Fluorescent biosensors play a vital role in drug discovery and in cancer. Biosensor applications are prevalent in the plant biology sector to find out the missing links required in metabolic processes. Other applications are involved in defence, clinical sector, and for marine applications. PMID:27195214

  13. Establishment and validation of a method for multi-dose irradiation of cells in 96-well microplates

    SciTech Connect

    Abatzoglou, Ioannis; Zois, Christos E.; Pouliliou, Stamatia

    2013-02-15

    Highlights: ► We established a method for multi-dose irradiation of cell cultures within a 96-well plate. ► Equations to adjust to preferable dose levels are produced and provided. ► Up to eight different dose levels can be tested in one microplate. ► This method results in fast and reliable estimation of radiation dose–response curves. -- Abstract: Microplates are useful tools in chemistry, biotechnology and molecular biology. In radiobiology research, these can be also applied to assess the effect of a certain radiation dose delivered to the whole microplate, to test radio-sensitivity, radio-sensitization or radio-protection. Whether different radiation doses can be accurately applied to a single 96-well plate to further facilitate and accelerated research by one hand and spare funds on the other, is a question dealt in the current paper. Following repeated ion-chamber, TLD and radiotherapy planning dosimetry we established a method for multi-dose irradiation of cell cultures within a 96-well plate, which allows an accurate delivery of desired doses in sequential columns of the microplate. Up to eight different dose levels can be tested in one microplate. This method results in fast and reliable estimation of radiation dose–response curves.

  14. A luminescent nisin biosensor

    NASA Astrophysics Data System (ADS)

    Immonen, Nina; Karp, Matti

    2006-02-01

    Nisin is a lantibiotic, an antibacterial peptide produced by certain Lactococcus lactis strains that kills or inhibits the growth of other bacteria. Nisin is widely used as a food preservative, and its long-time use suggests that it can be generally regarded as safe. We have developed a method for determining the amount of nisin in food samples that is based on luminescent biosensor bacteria. Bacterial luciferase operon luxABCDE was inserted into plasmid pNZ8048, and the construct was transformed by electroporation into Lc. lactis strain NZ9800, whose ability to produce nisin has been erased by deletion of the gene nisA. The operon luxABCDE has been modified to be functional in gram-positive bacteria to confer a bioluminescent phenotype without the requirement of adding an exogenous substrate. In the plasmid pNZ8048, the operon was placed under control of the nisin-inducible nisA promoter. The chromosomal nisRK genes of Lc. lactis NZ9800 allow it to sense nisin in the environment and relay this signal via signal transduction proteins NisK and NisR to initiate transcription from nisA promoter. In the case of our sensor bacteria, this leads to production of luciferase and, thus, luminescence that can be directly measured from living bacteria. Luminescence can be detected as early as within minutes of induction. The nisin assay described here provides a detection limit in the sub-picogram level per ml, and a linear area between 1 - 1000 pg/ml. The sensitivity of this assay exceeds the performance of all previously published methods.

  15. Electrical Percolation Based Biosensors

    PubMed Central

    Bruck, Hugh Alan; Yang, Minghui; Kostov, Yordan; Rasooly, Avraham

    2013-01-01

    A new approach to label free biosensing has been developed based on the principle of “electrical percolation”. In electrical percolation, long-range electrical connectivity is formed in randomly oriented and distributed systems of discrete elements. By applying this principle to biological interactions, it is possible to measure biological components both directly and electronically. The main element for electrical percolation biosensor is the biological semiconductor (BSC) which is a multi-layer 3-D carbon nanotube-antibody network. In the BSC, molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. BSCs can be fabricated by immobilizing conducting elements, such as pre-functionalized single-walled carbon nanotubes (SWNTs)-antibody complex, directly onto a substrate, such as a Poly(methyl methacrylate) (PMMA) surface (also known as plexi-glass or Acrylic). BSCs have been demonstrated for direct (label-free) electronic measurements of antibody-antigen binding using SWNTs. If the concentration of the SWNT network is slightly above the electrical percolation threshold, then binding of a specific antigen to the pre-functionalized SWNT dramatically increases the electrical resistance due to changes in the tunneling between the SWNTs. Using anti-Staphylococcal enterotoxin B (SEB) IgG as a “gate” and SEB as an “actuator”, it was demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/ml. Based on this concept, an automated configuration for BSCs is described here that enables real time continuous detection. The new BSC configuration may permit assembly of multiple sensors on the same chip to create “Biological Central Processing Units (CPUs)” with multiple biological elements, capable of processing and sorting out information on multiple analytes simultaneously. PMID:24041756

  16. Rapid acid digestion and simple microplate method for milk iodine determination.

    PubMed

    Hedayati, Mehdi; Ordookhani, Arash; Daneshpour, Maryam Sadat; Azizi, Fereidoun

    2007-01-01

    Iodine deficiency leads to deficiency of thyroid hormones, which causes mental retardation in infant. Laboratory confirmation is important in its diagnosis. The major problems associated with the existing methods for iodine determination in milk samples are: 1) nonsafe alkaline solution; 2) harsh thermal condition; and 3) extra time required to complete various steps. In this study, a simple and rapid colorimetric method was investigated, which used acid digestion in combination with a rapid microplate reading format method to determine the total iodine content in milk. Sample digestion was done on 50 microL milk in metavanadate/perchloric, at 230 degrees C for 10 min. After digestion, iodine determination was based on the Sandell-Kolthoff reaction. The reaction results were read in 96-well microplates by an enzyme-linked immunosorbent assay (ELISA) reader. The determination range of the assay was between 2 and 40 microg/dL. The within-run coefficient of variation percent in three levels (3, 12, and 36 microg/dL) ranged from 6.7 to 9.3 and between-run coefficients of variation ranged from 8.6 to 12.3%. The results obtained (n=70) by the optimized method have good correlation with the results of alkaline incineration as a reference method (n=70; r2=0.907; y=0.952x+1.77). Recovery tests for accuracy assessment in six levels from 6.2 to 34.2 microg/dL) were between 91.3 and 113%. This method has enabled us to achieve 0.12 microg/dL sensitivity. The results of this study show that a quick acid digestion combined with mild thermal and low sample volume with a quick reading of assay results were the main advantages of the acid digestion and microplate reading format. PMID:17847102

  17. The August 2002 earthquake sequence in north Afar: Insights into the neotectonics of the Danakil microplate

    NASA Astrophysics Data System (ADS)

    Ayele, Atalay; Stuart, Graham; Bastow, Ian; Keir, Derek

    2007-06-01

    In August 2002, there was high seismic activity in Afar concentrated at the plateau margin of the northern Ethiopian rift east of Mekele, near the western part of the Danakil microplate. The spatial and temporal distributions of this seismic activity over four weeks indicate the NNW propagation of the Gulf of Aden rift across the Afar Depression towards the western Ethiopian plateau. Fault plane solutions for six larger earthquakes from the August 2002 sequence are estimated from moment tensor inversion of local broadband waveform data. The results show only normal faulting on NNW trending and NE dipping faults, which agree with tectonics of the area and distribution of aftershocks. No strike-slip component is observed in any of our fault plane solutions or those of other workers including Harvard CMT solutions in the region. Such motion would be indicative of oblique-slip deformation between the Nubian plate and the Danakil microplate consistent with counter-clockwise rotation of the microplate. Hypocentral depths of well-constrained events are 5-7 km, which is the approximate elastic plate thickness in the Main Ethiopian rift, possibly indicating the depth to the brittle-ductile transition zone in this part of the Afar Depression. The shallowness of the depth estimates agree with the macroseismic reports available from a wide area in northern Ethiopia. Potential future shallow crustal deformation may cause significant loss of human life and damage to property in the densely populated highland region around Mekele unless measures are taken in improving building standards. The b-value for this sequence is estimated to be 0.66 using a least squares fit, while it is 0.67 ± 0.16 from a maximum-likelihood approach. This estimated b-value is low or the frequency of occurrence of relatively larger magnitude events is high indicating that it is a highly stressed region as evidenced by the recent increase of the seismicity in the area.

  18. Microplate-Based Characterization of Protein-Phosphoinositide Binding Interactions Using a Synthetic Biotinylated Headgroup Analogue

    PubMed Central

    Gong, Denghuang; Smith, Matthew D.; Manna, Debasis; Bostic, Heidi E.; Cho, Wonhwa; Best, Michael D.

    2009-01-01

    Membrane lipids act as important regulators of a litany of important physiological and pathophysiological events. Many of them act as site-specific ligands for cytosolic proteins in binding events that recruit receptors to the cell surface and control both protein function and subcellular localization. Phosphatidylinositol phosphates (PIPns) are a family of signaling lipids that regulate numerous cellular processes by interacting with a myriad of protein binding modules. Characterization of PIPn-binding proteins has been hampered by the lack of a rapid and convenient quantitative assay. Herein, microplate-based detection is presented as an effective approach to characterizing protein-PIPn binding interactions at the molecular level. With this assay, the binding of proteins to isolated PIPn headgroups is detected with high sensitivity using a platform that is amenable to high-throughput screening. In the studies described herein, biotinylated PI-(4,5)-P2 headgroup analogue 1 was designed, synthesized and immobilized onto 96-well streptavidin-coated microplates to study receptor binding. This assay was used to characterize the binding of the PH domain of β-spectrin to this headgroup. The high affinity interaction that was detected for surface association (Kd, surf = 6 nM ±3), demonstrates that receptor binding modules can form high affinity interactions with lipid headgroups outside of a membrane environment. The results also indicate the feasibility of the assay for rapid characterization of PIPn-binding proteins as well as the promise for high-throughput analysis of protein-PIPn binding interactions. Finally, this assay was also employed to characterize the inhibition of the binding of receptors to the PIPn-derivatized microplates using solution phase competitors. This showcases the viability of this assay for rapid screening of inhibitors of PIPn-binding proteins. PMID:19182890

  19. In vitro toxicity testing with microplate cell cultures: Impact of cell binding.

    PubMed

    Gülden, Michael; Schreiner, Jeannine; Seibert, Hasso

    2015-06-01

    In vitro generated data on toxic potencies are generally based on nominal concentrations. However, cellular and extracellular binding and elimination processes may reduce the available free fraction of a compound. Then, nominal effective concentrations do not represent appropriate measures of toxic exposure in vitro and underestimate toxic potencies. In this study it was investigated whether cell binding can affect the availability of chemicals in microplate based toxicity assays. To this end the cytotoxicity of compounds like mercury chloride, digitonin and alcohol ethoxylates, accumulated by cells via different modes, was investigated in 96-well microplate cultures with varying concentrations of Balb/c 3T3 cells. The median effective nominal concentrations of all but one of the tested compounds depended linearly from the cell concentration. Applying a previously developed equilibrium distribution model cell concentration-independent median effective extracellular concentrations and cell burdens, respectively, could be calculated. The compounds were accumulated by the cells with bioconcentration factors, BCF, between 480 and ≥ 25,000. Cell binding of the alcohol ethoxylates was correlated with their lipophilicity. The results show that significant cell binding can occur even at the small cell volume fractions (∼ 1 × 10(-5) to 3 × 10(-3) L/L) encountered in microplate assays. To what extent cell binding affects the bioavailability depends on the BCF and the cell volume fraction. EC50 measurements in the presence of at least two different cell concentrations allow for excluding or detecting significant cell binding and for determining more appropriate measures of toxic exposure in vitro like median effective extracellular (free) concentrations or cell burdens. PMID:24291469

  20. The Geometry of the Subducting Slabs Beneath the PRVI Microplate Based on 3D Tomography

    NASA Astrophysics Data System (ADS)

    Xu, X.; Keller, G. R.; Holland, A. A.; Keranen, K. M.; Li, H.

    2011-12-01

    The Puerto Rico and the Virgin Islands (PRVI) microplate is located between two subduction zones, with the Puerto Rico trench to the north and the Muertos trough to the south. The Puerto Rico trench is caused by southward-directed subduction of the North American Plate, and the Muertos trough is the northern boundary of the Caribbean Plate. There is no active volcanism on Puerto Rico; however, earthquake depths and seismic tomography imply that the slab of Caribbean plate continues northward beneath Puerto Rico. Puerto Rico overlies these two slabs with extension to both the west (Mona Passage) and southeast (Anacapa Passage). The cause of the extension is unknown, but GPS measurements show that Puerto Rico is experiencing anti-clockwise rotation, and the extension associated with the Anacapa Passage may be produced by this rotation. To the west, it is debated whether the Mona Passage is a boundary between two micro-plates or simple a local rift basin. To address the sources of the extension and the cause of the rotation, we are investigating if the deep structures can be the dynamic source for the observed kinematic movements. We collected data on earthquakes occurring between 2009-2011 in the PRVI region and relocated them using the SEISAN code provided by the Institute of Solid Earth Physics, University of Bergen. The FMTOMO code from Australian National University was used for 3D tomography from P and S wave arrival times. By comparing the relocated epicenters and the 3D tomography results, the subducting slabs were identified. When integrated with the results of previous studies, the geometric model of the slabs is a critical key to understanding the evolution of the PRVI microplate in the past and the future.

  1. Sensitive microplate assay for the detection of proteolytic enzymes using radiolabeled gelatin

    SciTech Connect

    Robertson, B.D.; Kwan-Lim, G.E.; Maizels, R.M.

    1988-07-01

    A sensitive, microplate assay is described for the detection of a wide range of proteolytic enzymes, using radio-iodine-labeled gelatin as substrate. The technique uses the Bolton-Hunter reagent to label the substrate, which is then coated onto the wells of polyvinyl chloride microtiter plates. By measuring the radioactivity released the assay is able to detect elastase, trypsin, and collagenase in concentrations of 1 ng/ml or less, while the microtiter format permits multiple sample handling and minimizes sample volumes required for analysis.

  2. Determination of N-species in soil extracts using microplate techniques.

    PubMed

    Shand, Charles A; Williams, Berwyn L; Coutts, Grace

    2008-01-15

    Colourimetric methods for the determination of NO(3)(-), NH(4)(+) and total N in water extracts of soils using 96-well microplate techniques are described. Nitrate was determined by azo dye formation after reduction to NO(2)(-) using a solution of hydrazine sulphate. Ammonium in the soil extracts was purified and concentrated by diffusion as NH(3) from small volumes (750microL) of extract treated with MgO into a H(2)SO(4) collector using a double-plate, MicroResp method and subsequently determined by the Berthelot reaction. For the determination of total N, samples were oxidised with K(2)S(2)O(8) at 110 degrees C in a 96x1.1mL polytetrafluoroethylene block with a lid that closed individual wells. The oxidised solutions were transferred to standard plates for colourimetric analysis of NO(3)(-). The recovery of N, measured as NO(3)(-), from NH(4)NO(3) and a range of organic-N compounds was >95%. The limits of quantitation of the colourimetic assays were 0.020mgNL(-1) for NO(3)(-) and 0.051mgNL(-1) for NH(4)(+). The methods were tested on water extracts derived from a range of 10 nutrient poor soils from Scotland. There were acceptable linear correlations between the results obtained by established methods. For soil extracts analysed by the microplate method, the relationship for NO(3)(-) was 1.03x result from ion chromatography+0.0055 (R(2)=0.9961); for NH(4)(+) determined by the microplate method, the relationship was 0.9696xresult from a discrete analyser-0.0169 (R(2)=0.9757) and for total N determined by oxidation in the PTFE microplate the relationship was 0.9435xresult obtained by combustion+0.0489 (R(2)=0.9743). Purification of the NH(4)(+) in water extracts from the 10 different soils by the diffusion method did not result in any systematic difference (paired t-test, p=0.05) between measured concentration values determined before and after diffusion. PMID:18371688

  3. Self-assembly of gold nanorods into vertically aligned, rectangular microplates with a supercrystalline structure

    NASA Astrophysics Data System (ADS)

    Xiao, Junyan; Li, Zhe; Ye, Xiaozhou; Ma, Yurong; Qi, Limin

    2013-12-01

    Vertically aligned, supercrystalline microplates with a well-defined rectangular shape were fabricated in a large area through self-assembly of gold nanorods by a novel bulk solution evaporation method. This evaporative self-assembly strategy involving continuous movement of the contact line can prevent the coffee-ring effect, thus allowing uniform deposition of discrete GNR superstructures over a large area and favoring the formation of GNR supercrystals with geometrically symmetric shapes. A mechanism based on the continuing nucleation and growth of smectic GNR superstructures accompanying the movement of the contact line was put forward for the formation of the unique GNR supercrystal arrays. Based on this mechanism, a micropatterned substrate was designed to control the nucleation location and growth direction, leading to the spontaneous self-assembly of nearly parallel arrays of vertically aligned, supercrystalline microplates of GNRs. The obtained rectangular-plate-shaped GNR supercrystals exhibited interesting anisotropic optical reflection properties, which were revealed by polarized light microscopy.Vertically aligned, supercrystalline microplates with a well-defined rectangular shape were fabricated in a large area through self-assembly of gold nanorods by a novel bulk solution evaporation method. This evaporative self-assembly strategy involving continuous movement of the contact line can prevent the coffee-ring effect, thus allowing uniform deposition of discrete GNR superstructures over a large area and favoring the formation of GNR supercrystals with geometrically symmetric shapes. A mechanism based on the continuing nucleation and growth of smectic GNR superstructures accompanying the movement of the contact line was put forward for the formation of the unique GNR supercrystal arrays. Based on this mechanism, a micropatterned substrate was designed to control the nucleation location and growth direction, leading to the spontaneous self-assembly of

  4. DESIGN OF INTEGRATING WAVEGUIDE BIOSENSOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Integrating Waveguide Biosensor allows for rapid and sensitive detection of pathogenic agents, cells and proteins via immunoassay or PCR products. The analytes are captured on the surface of the waveguide and then tagged with fluorescent labels. The waveguides are illuminated by excitation light...

  5. Fiber optic-based biosensor

    NASA Technical Reports Server (NTRS)

    Ligler, Frances S.

    1991-01-01

    The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

  6. Improved Ion-Channel Biosensors

    NASA Technical Reports Server (NTRS)

    Nadeau, Jay; White, Victor; Dougherty, Dennis; Maurer, Joshua

    2004-01-01

    An effort is underway to develop improved biosensors of a type based on ion channels in biomimetic membranes. These sensors are microfabricated from silicon and other materials compatible with silicon. As described, these sensors offer a number of advantages over prior sensors of this type.

  7. A high content assay for biosensor validation and for examining stimuli that affect biosensor activity

    PubMed Central

    Slattery, Scott D.; Hahn, Klaus M.

    2015-01-01

    Biosensors are valuable tools used to monitor many different protein behaviors in vivo. Demand for new biosensors is high, but their development and characterization can be difficult. During biosensor design, it is necessary to evaluate the effects of different biosensor structures on specificity, brightness, and fluorescence responses. By co-expressing the biosensor with upstream proteins that either stimulate or inhibit the activity reported by the biosensor, one can determine the difference between the biosensor’s maximally activated and inactivated state, and examine response to specific proteins. This involves considerable labor and expense, as expression conditions must be optimized to saturate the biosensor with the regulator, and multiple replicates and controls are required. We describe here a protocol for biosensor validation in a 96-well plate format using an automated microscope. This protocol produces dose-response curves, enables efficient examination of many parameters, and unlike cell suspension assays allows visual inspection (eg for cell health and biosensor or regulator localization). Optimization of single chain and dual chain Rho GTPase biosensors is addressed, but the assay is applicable to any biosensor that can be expressed or otherwise loaded in adherent cells. The assay can also be used for purposes other than biosensor validation, using a well-characterized biosensor as a readout for variations in upstream molecules. PMID:25447074

  8. Revision of the genera Microplitis and Snellenius (Hymenoptera, Braconidae, Microgastrinae) from Area de Conservacion Guanacaste, Costa Rica, with a key to all species previously described from Mesoamerica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genera Microplitis and Snellenius (Hymenoptera: Braconidae, Microgastrinae) from Area de Conservacion Guanacaste (ACG), Costa Rica, are revised. A total of 28 new species are described: 23 of Snellenius (the first record for Mesoamerica) and five of Microplitis. A key is provided to all new spec...

  9. Examining the effects of self-assembled monolayers on nanoporous gold based amperometric glucose biosensors.

    PubMed

    Xiao, Xinxin; Li, Hui; Wang, Meng'en; Zhang, Kai; Si, Pengchao

    2014-01-21

    Nanoporous gold (NPG) based biosensors have been constructed by covalently immobilizing glucose oxidase (GOx) onto self-assembled monolayers (SAMs). With p-benzoquinone (BQ) as a mediator, diffusion behavior and amperometric biosensor performance are evaluated by electrochemical characterization. The enzyme modified electrodes are demonstrated to show a thickness-sensitive behavior. Compared with planar polycrystalline gold, the unique porous structure of NPG has also been characterized via an electrochemical surface reconstruction process. Single-crystal gold-like electrochemical behavior on NPG and a comprehensive understanding of its impacts on sensor performance have been proposed. PMID:24256634

  10. Nanoshell-Enhanced Raman Spectroscopy on a Microplate for Staphylococcal Enterotoxin B Sensing.

    PubMed

    Wang, Wenbin; Wang, Weiwei; Liu, Liqiang; Xu, Liguang; Kuang, Hua; Zhu, Jianping; Xu, Chuanlai

    2016-06-22

    A sensitive surface-enhanced Raman scattering (SERS) immunosensor based on the Au nanoparticle (Au NP) shell structure was developed to detect staphylococcal enterotoxin B (SEB) on a microplate. Au NPs modified with 4-nitrothiophenol (4-NTP) and coated with Ag shell of controlled thickness at 6.6 nm exhibited excellent SERS intensity and were used as signal reporters in the detection of SEB. The engaged 4-NTP allowed the significant electromagnetic enhancement between Au NPs and the Ag shell and prevented the dissociation of the Raman reporter. More importantly, 4-NTP-differentiated SERS signals between the sample and microplate. The SERS-based immunosensor had a limit of detection of 1.3 pg/mL SEB. Analysis of SEB-spiked milk samples revealed that the developed method had high accuracy. Therefore, the SERS-encoded Au@Ag core-shell structure-based immunosensor is promising for the detection of biotoxins, pathogens, and environmental pollutants. PMID:27193082

  11. A paper/polymer hybrid microfluidic microplate for rapid quantitative detection of multiple disease biomarkers.

    PubMed

    Sanjay, Sharma T; Dou, Maowei; Sun, Jianjun; Li, XiuJun

    2016-01-01

    Enzyme linked immunosorbent assay (ELISA) is one of the most widely used laboratory disease diagnosis methods. However, performing ELISA in low-resource settings is limited by long incubation time, large volumes of precious reagents, and well-equipped laboratories. Herein, we developed a simple, miniaturized paper/PMMA (poly(methyl methacrylate)) hybrid microfluidic microplate for low-cost, high throughput, and point-of-care (POC) infectious disease diagnosis. The novel use of porous paper in flow-through microwells facilitates rapid antibody/antigen immobilization and efficient washing, avoiding complicated surface modifications. The top reagent delivery channels can simply transfer reagents to multiple microwells thus avoiding repeated manual pipetting and costly robots. Results of colorimetric ELISA can be observed within an hour by the naked eye. Quantitative analysis was achieved by calculating the brightness of images scanned by an office scanner. Immunoglobulin G (IgG) and Hepatitis B surface Antigen (HBsAg) were quantitatively analyzed with good reliability in human serum samples. Without using any specialized equipment, the limits of detection of 1.6 ng/mL for IgG and 1.3 ng/mL for HBsAg were achieved, which were comparable to commercial ELISA kits using specialized equipment. We envisage that this simple POC hybrid microplate can have broad applications in various bioassays, especially in resource-limited settings. PMID:27456979

  12. Highly Multiplexed RNA Aptamer Selection using a Microplate-based Microcolumn Device

    PubMed Central

    Reinholt, Sarah J.; Ozer, Abdullah; Lis, John T.; Craighead, Harold G.

    2016-01-01

    We describe a multiplexed RNA aptamer selection to 19 different targets simultaneously using a microcolumn-based device, MEDUSA (Microplate-based Enrichment Device Used for the Selection of Aptamers), as well as a modified selection process, that significantly reduce the time and reagents needed for selections. We exploited MEDUSA’s reconfigurable design between parallel and serially-connected microcolumns to enable the use of just 2 aliquots of starting library, and its 96-well microplate compatibility to enable the continued use of high-throughput techniques in downstream processes. Our modified selection protocol allowed us to perform the equivalent of a 10-cycle selection in the time it takes for 4 traditional selection cycles. Several aptamers were discovered with nanomolar dissociation constants. Furthermore, aptamers were identified that not only bound with high affinity, but also acted as inhibitors to significantly reduce the activity of their target protein, mouse decapping exoribonuclease (DXO). The aptamers resisted DXO’s exoribonuclease activity, and in studies monitoring DXO’s degradation of a 30-nucleotide substrate, less than 1 μM of aptamer demonstrated significant inhibition of DXO activity. This aptamer selection method using MEDUSA helps to overcome some of the major challenges with traditional aptamer selections, and provides a platform for high-throughput selections that lends itself to process automation. PMID:27432610

  13. A paper/polymer hybrid microfluidic microplate for rapid quantitative detection of multiple disease biomarkers

    PubMed Central

    Sanjay, Sharma T.; Dou, Maowei; Sun, Jianjun; Li, XiuJun

    2016-01-01

    Enzyme linked immunosorbent assay (ELISA) is one of the most widely used laboratory disease diagnosis methods. However, performing ELISA in low-resource settings is limited by long incubation time, large volumes of precious reagents, and well-equipped laboratories. Herein, we developed a simple, miniaturized paper/PMMA (poly(methyl methacrylate)) hybrid microfluidic microplate for low-cost, high throughput, and point-of-care (POC) infectious disease diagnosis. The novel use of porous paper in flow-through microwells facilitates rapid antibody/antigen immobilization and efficient washing, avoiding complicated surface modifications. The top reagent delivery channels can simply transfer reagents to multiple microwells thus avoiding repeated manual pipetting and costly robots. Results of colorimetric ELISA can be observed within an hour by the naked eye. Quantitative analysis was achieved by calculating the brightness of images scanned by an office scanner. Immunoglobulin G (IgG) and Hepatitis B surface Antigen (HBsAg) were quantitatively analyzed with good reliability in human serum samples. Without using any specialized equipment, the limits of detection of 1.6 ng/mL for IgG and 1.3 ng/mL for HBsAg were achieved, which were comparable to commercial ELISA kits using specialized equipment. We envisage that this simple POC hybrid microplate can have broad applications in various bioassays, especially in resource-limited settings. PMID:27456979

  14. Metabolic activities of five botryticides against Botrytis cinerea examined using the Biolog FF MicroPlate.

    PubMed

    Wang, Hancheng; Wang, Jin; Li, Licui; Hsiang, Tom; Wang, Maosheng; Shang, Shenghua; Yu, Zhihe

    2016-01-01

    Tobacco grey mold caused by Botrytis cinerea is an important fungal disease worldwide. Boscalid, carbendazim, iprodione, pyrimethanil and propiconazole are representative botryticides for grey mold management. This research investigated the sensitivities of B. cinerea from tobacco to these chemicals using the Biolog FF Microplate. All five chemicals showed inhibitory activity, with average EC50 values of 0.94, 0.05, 0.50, 0.61 and 0.31 μg ml(-1), respectively. B. cinerea metabolized 96.8% of tested carbon sources, including 29 effectively and 33 moderately, but the metabolic fingerprints differed under pressures imposed by these botryticides. For boscalid, B. cinerea was unable to metabolize many substrates related to tricarboxylic acid cycle. For carbendazim, carbon sources related to glycolysis were not metabolized. For iprodione, use of most carbon substrates was weakly inhibited, and the metabolic profile was similar to that of the control. For propiconazole, no carbon substrates were metabolized and the physiological and biochemical functions of the pathogen were totally inhibited. These findings provide useful information on metabolic activities of these botryticides, and may lead to future applications of the Biolog FF Microplate for examining metabolic effects of other fungicides on other fungi, as well as providing a metabolic fingerprint of B. cinerea that could be useful for identification. PMID:27491536

  15. An Analytical Model for Squeeze-Film Damping of Perforated Torsional Microplates Resonators

    PubMed Central

    Li, Pu; Fang, Yuming

    2015-01-01

    Squeeze-film damping plays a significant role in the performance of micro-resonators because it determines their quality factors. Perforations in microstructures are often used to control the squeeze-film damping in micro-resonators. To model the perforation effects on the squeeze-film damping, many analytical models have been proposed, however, most of the previous models have been concerned with the squeeze-film damping due to the normal motion between the perforated vibrating plate and a fixed substrate, while there is a lack of works that model the squeeze-film damping of perforated torsion microplates, which are also widely used in MEMS devices. This paper presents an analytical model for the squeeze-film damping of perforated torsion microplates. The derivation in this paper is based on a modified Reynolds equation that includes compressibility and rarefaction effects. The pressure distribution under the vibrating plate is obtained using the double sine series. Closed-form expressions for the stiffness and the damping coefficients of the squeeze-film are derived. The accuracy of the model is verified by comparing its results with the finite element method (FEM) results and the experimental results available in the literature. The regime of validity and limitations of the present model are assessed. PMID:25815453

  16. Biocompatibility of microplates for culturing epithelial renal cells evaluated by a microcalorimetric technique.

    PubMed

    Xie, Y; DePierre, J W; Nässberger, L

    2000-09-01

    In the present study we have developed a microcalorimetric procedure which allows convenient investigation of biocompatibility in a microsystem. We examined the biocompatibility of a porcine renal epithelial tubule cell line LLC-PK1 and a human primary renal epithelial tubule cell (RPTEC) with microplates composed of three different materials, i.e. Thermanox, transparent film and titanium. All three materials showed equal biocompatibility with LLC-PK1 cells, judging from the attainment of steady-state power curves and the same rate of heat production per cell (2.5 microW / microg DNA). The human renal cells were poorly biocompatible with the Thermanox and transparent film. However, on titanium the RPTEC cell did adhere, as demonstrated by a steady-state power curve. The human cells also showed a higher metabolic activity (3.0 microW / microg DNA), than did LLC-PK1 cells cultured on the same type of microplates. In research on biocompatibility there is a need for alternatives to experimental animal investigations. The present technique allows studies of cellular interactions with different biomaterials in a rapid and standardized manner and may therefore prove to be a useful screening procedure. PMID:15348389

  17. Inline chemical process analysis in micro-plants based on thermoelectric flow and impedimetric sensors

    NASA Astrophysics Data System (ADS)

    Jacobs, T.; Kutzner, C.; Kropp, M.; Brokmann, G.; Lang, W.; Steinke, A.; Kienle, A.; Hauptmann, P.

    2010-10-01

    In micro-plants, as used in chemical micro-process engineering, an integrated inline analytics is regarded as an important factor for the development and optimization of chemical processes. Up to now, there is a lack of sensitive, robust and low-priced micro-sensors for monitoring mixing and chemical conversion in micro-fluidic channels. In this paper a novel sensor system combining an impedimetric sensor and a novel pressure stable thermoelectric flow sensor for monitoring chemical reactions in micro-plants is presented. The CMOS-technology-based impedimetric sensor mainly consists of two capacitively coupled interdigital electrodes on a silicon chip. The thermoelectric flow sensor consists of a heater in between two thermopiles on a perforated membrane. The pulsed and constant current feeds of the heater were analyzed. Both sensors enable the analysis of chemical conversion by means of changes in the thermal and electrical properties of the liquid. The homogeneously catalyzed synthesis of n-butyl acetate as a chemical model system was studied. Experimental results revealed that in an overpressure regime, relative changes of less than 1% in terms of thermal and electrical properties can be detected. Furthermore, the transition from one to two liquid phases accompanied by the change in slug flow conditions could be reproducibly detected.

  18. Microplate-reader method for the rapid analysis of copper in natural waters with chemiluminescence detection

    PubMed Central

    Durand, Axel; Chase, Zanna; Remenyi, Tomas; Quéroué, Fabien

    2013-01-01

    We have developed a method for the determination of copper in natural waters at nanomolar levels. The use of a microplate-reader minimizes sample processing time (~25 s per sample), reagent consumption (~120 μL per sample), and sample volume (~700 μL). Copper is detected by chemiluminescence. This technique is based on the formation of a complex between copper and 1,10-phenanthroline and the subsequent emission of light during the oxidation of the complex by hydrogen peroxide. Samples are acidified to pH 1.7 and then introduced directly into a 24-well plate. Reagents are added during data acquisition via two reagent injectors. When trace metal clean protocols are employed, the reproducibility is generally less than 7% on blanks and the detection limit is 0.7 nM for seawater and 0.4 nM for freshwater. More than 100 samples per hour can be analyzed with this technique, which is simple, robust, and amenable to at-sea analysis. Seawater samples from Storm Bay in Tasmania illustrate the utility of the method for environmental science. Indeed other trace metals for which optical detection methods exist (e.g., chemiluminescence, fluorescence, and absorbance) could be adapted to the microplate-reader. PMID:23335917

  19. Highly Multiplexed RNA Aptamer Selection using a Microplate-based Microcolumn Device.

    PubMed

    Reinholt, Sarah J; Ozer, Abdullah; Lis, John T; Craighead, Harold G

    2016-01-01

    We describe a multiplexed RNA aptamer selection to 19 different targets simultaneously using a microcolumn-based device, MEDUSA (Microplate-based Enrichment Device Used for the Selection of Aptamers), as well as a modified selection process, that significantly reduce the time and reagents needed for selections. We exploited MEDUSA's reconfigurable design between parallel and serially-connected microcolumns to enable the use of just 2 aliquots of starting library, and its 96-well microplate compatibility to enable the continued use of high-throughput techniques in downstream processes. Our modified selection protocol allowed us to perform the equivalent of a 10-cycle selection in the time it takes for 4 traditional selection cycles. Several aptamers were discovered with nanomolar dissociation constants. Furthermore, aptamers were identified that not only bound with high affinity, but also acted as inhibitors to significantly reduce the activity of their target protein, mouse decapping exoribonuclease (DXO). The aptamers resisted DXO's exoribonuclease activity, and in studies monitoring DXO's degradation of a 30-nucleotide substrate, less than 1 μM of aptamer demonstrated significant inhibition of DXO activity. This aptamer selection method using MEDUSA helps to overcome some of the major challenges with traditional aptamer selections, and provides a platform for high-throughput selections that lends itself to process automation. PMID:27432610

  20. A paper/polymer hybrid microfluidic microplate for rapid quantitative detection of multiple disease biomarkers

    NASA Astrophysics Data System (ADS)

    Sanjay, Sharma T.; Dou, Maowei; Sun, Jianjun; Li, Xiujun

    2016-07-01

    Enzyme linked immunosorbent assay (ELISA) is one of the most widely used laboratory disease diagnosis methods. However, performing ELISA in low-resource settings is limited by long incubation time, large volumes of precious reagents, and well-equipped laboratories. Herein, we developed a simple, miniaturized paper/PMMA (poly(methyl methacrylate)) hybrid microfluidic microplate for low-cost, high throughput, and point-of-care (POC) infectious disease diagnosis. The novel use of porous paper in flow-through microwells facilitates rapid antibody/antigen immobilization and efficient washing, avoiding complicated surface modifications. The top reagent delivery channels can simply transfer reagents to multiple microwells thus avoiding repeated manual pipetting and costly robots. Results of colorimetric ELISA can be observed within an hour by the naked eye. Quantitative analysis was achieved by calculating the brightness of images scanned by an office scanner. Immunoglobulin G (IgG) and Hepatitis B surface Antigen (HBsAg) were quantitatively analyzed with good reliability in human serum samples. Without using any specialized equipment, the limits of detection of 1.6 ng/mL for IgG and 1.3 ng/mL for HBsAg were achieved, which were comparable to commercial ELISA kits using specialized equipment. We envisage that this simple POC hybrid microplate can have broad applications in various bioassays, especially in resource-limited settings.

  1. A simple and rapid microplate assay for glycoprotein-processing glycosidases

    SciTech Connect

    Kang, M.S.; Zwolshen, J.H.; Harry, B.S.; Sunkara, P.S. )

    1989-08-15

    A simple and convenient microplate assay for glycosidases involved in the glycoprotein-processing reactions is described. The assay is based on specific binding of high-mannose-type oligosaccharide substrates to concanavalin A-Sepharose, while monosaccharides liberated by enzymatic hydrolysis do not bind to concanavalin A-Sepharose. By the use of radiolabeled substrates (( 3H)glucose for glucosidases and (3H)mannose for mannosidases), the radioactivity in the liberated monosaccharides can be determined as a measure of the enzymatic activity. This principle was employed earlier for developing assays for glycosidases previously reported. These authors have reported the separation of substrate from the product by concanavalin A-Sepharose column chromatography. This procedure is handicapped by the fact that it cannot be used for a large number of samples and is time consuming. We have simplified this procedure and adapted it to the use of a microplate (96-well plate). This would help in processing a large number of samples in a short time. In this report we show that the assay is comparable to the column assay previously reported. It is linear with time and enzyme concentration and shows expected kinetics with castanospermine, a known inhibitor of alpha-glucosidase I.

  2. AgI microplate monocrystals with polar {0001} facets: spontaneous photocarrier separation and enhanced photocatalytic activity.

    PubMed

    Kuang, Qin; Zheng, Xiaoli; Yang, Shihe

    2014-02-24

    Elucidating the facet-dependent photocatalytic activity of semiconductor photocatalysts is important in improving the overall efficiency of photocatalysis. Furthermore, combining facet control with selective deposition of oxidation and/or reduction cocatalysts on specific faces of semiconductor photocatalysts is potentially an effective strategy to synergistically optimize the functionality of photocatalysts. In the present study, high-purity wurtzite-type β-AgI platelet microcrystals with polar {0001} facets were prepared by a facile polyvinylpyrrolidone-assisted precipitation reaction. The polar-faceted AgI microplates were used as archetypes to demonstrate preferential diametric migration (i.e., effective separation) of photogenerated electrons and holes along the c axis. Such vectorial electron-hole separation stems from the asymmetric surface structures, which give rise to distinct photoexcited reaction behaviors on the ±(0001) polar facets of wurtzite-type semiconductors. Furthermore, on selective deposition of Ag and MnOx (1.5microplates in degrading organic pollutants was dramatically enhanced thanks to the broad light-absorption range, strong dye-adsorption ability, and effective spatial separation of photocarriers. PMID:24449437

  3. Self-assembly of gold nanorods into vertically aligned, rectangular microplates with a supercrystalline structure.

    PubMed

    Xiao, Junyan; Li, Zhe; Ye, Xiaozhou; Ma, Yurong; Qi, Limin

    2014-01-21

    Vertically aligned, supercrystalline microplates with a well-defined rectangular shape were fabricated in a large area through self-assembly of gold nanorods by a novel bulk solution evaporation method. This evaporative self-assembly strategy involving continuous movement of the contact line can prevent the coffee-ring effect, thus allowing uniform deposition of discrete GNR superstructures over a large area and favoring the formation of GNR supercrystals with geometrically symmetric shapes. A mechanism based on the continuing nucleation and growth of smectic GNR superstructures accompanying the movement of the contact line was put forward for the formation of the unique GNR supercrystal arrays. Based on this mechanism, a micropatterned substrate was designed to control the nucleation location and growth direction, leading to the spontaneous self-assembly of nearly parallel arrays of vertically aligned, supercrystalline microplates of GNRs. The obtained rectangular-plate-shaped GNR supercrystals exhibited interesting anisotropic optical reflection properties, which were revealed by polarized light microscopy. PMID:24292548

  4. An analytical model for squeeze-film damping of perforated torsional microplates resonators.

    PubMed

    Li, Pu; Fang, Yuming

    2015-01-01

    Squeeze-film damping plays a significant role in the performance of micro-resonators because it determines their quality factors. Perforations in microstructures are often used to control the squeeze-film damping in micro-resonators. To model the perforation effects on the squeeze-film damping, many analytical models have been proposed, however, most of the previous models have been concerned with the squeeze-film damping due to the normal motion between the perforated vibrating plate and a fixed substrate, while there is a lack of works that model the squeeze-film damping of perforated torsion microplates, which are also widely used in MEMS devices. This paper presents an analytical model for the squeeze-film damping of perforated torsion microplates. The derivation in this paper is based on a modified Reynolds equation that includes compressibility and rarefaction effects. The pressure distribution under the vibrating plate is obtained using the double sine series. Closed-form expressions for the stiffness and the damping coefficients of the squeeze-film are derived. The accuracy of the model is verified by comparing its results with the finite element method (FEM) results and the experimental results available in the literature. The regime of validity and limitations of the present model are assessed. PMID:25815453

  5. Metabolic activities of five botryticides against Botrytis cinerea examined using the Biolog FF MicroPlate

    PubMed Central

    Wang, Hancheng; Wang, Jin; Li, Licui; Hsiang, Tom; Wang, Maosheng; Shang, Shenghua; Yu, Zhihe

    2016-01-01

    Tobacco grey mold caused by Botrytis cinerea is an important fungal disease worldwide. Boscalid, carbendazim, iprodione, pyrimethanil and propiconazole are representative botryticides for grey mold management. This research investigated the sensitivities of B. cinerea from tobacco to these chemicals using the Biolog FF Microplate. All five chemicals showed inhibitory activity, with average EC50 values of 0.94, 0.05, 0.50, 0.61 and 0.31 μg ml−1, respectively. B. cinerea metabolized 96.8% of tested carbon sources, including 29 effectively and 33 moderately, but the metabolic fingerprints differed under pressures imposed by these botryticides. For boscalid, B. cinerea was unable to metabolize many substrates related to tricarboxylic acid cycle. For carbendazim, carbon sources related to glycolysis were not metabolized. For iprodione, use of most carbon substrates was weakly inhibited, and the metabolic profile was similar to that of the control. For propiconazole, no carbon substrates were metabolized and the physiological and biochemical functions of the pathogen were totally inhibited. These findings provide useful information on metabolic activities of these botryticides, and may lead to future applications of the Biolog FF Microplate for examining metabolic effects of other fungicides on other fungi, as well as providing a metabolic fingerprint of B. cinerea that could be useful for identification. PMID:27491536

  6. Tiny Medicine: Nanomaterial-Based Biosensors

    PubMed Central

    Yun, Yeo-Heung; Eteshola, Edward; Bhattacharya, Amit; Dong, Zhongyun; Shim, Joon-Sub; Conforti, Laura; Kim, Dogyoon; Schulz, Mark J.; Ahn, Chong H.; Watts, Nelson

    2009-01-01

    Tiny medicine refers to the development of small easy to use devices that can help in the early diagnosis and treatment of disease. Early diagnosis is the key to successfully treating many diseases. Nanomaterial-based biosensors utilize the unique properties of biological and physical nanomaterials to recognize a target molecule and effect transduction of an electronic signal. In general, the advantages of nanomaterial-based biosensors are fast response, small size, high sensitivity, and portability compared to existing large electrodes and sensors. Systems integration is the core technology that enables tiny medicine. Integration of nanomaterials, microfluidics, automatic samplers, and transduction devices on a single chip provides many advantages for point of care devices such as biosensors. Biosensors are also being used as new analytical tools to study medicine. Thus this paper reviews how nanomaterials can be used to build biosensors and how these biosensors can help now and in the future to detect disease and monitor therapies. PMID:22291565

  7. Plasmonic nanoparticles: Towards the fabrication of biosensors

    NASA Astrophysics Data System (ADS)

    Shen, Hui

    2015-07-01

    Au and Ag nanoparticles are mainly employed in the fabrication of biosensors owing to their unique optical properties compared to other noble metal nanoparticles. Many biosensors are fabricated for the rapid detection of different analytes such as organic and inorganic molecules, biomolecules like DNA, proteins, biotoxins and pathogens. In this mini review we mainly discuss on the usage of Au and Ag nanoparticles for the fabrication of colorimetric, SERS and two photon based photoluminescence biosensors.

  8. Recent Development in Optical Fiber Biosensors

    PubMed Central

    Bosch, María Espinosa; Sánchez, Antonio Jesús Ruiz; Rojas, Fuensanta Sánchez; Ojeda, Catalina Bosch

    2007-01-01

    Remarkable developments can be seen in the field of optical fibre biosensors in the last decade. More sensors for specific analytes have been reported, novel sensing chemistries or transduction principles have been introduced, and applications in various analytical fields have been realised. This review consists of papers mainly reported in the last decade and presents about applications of optical fiber biosensors. Discussions on the trends in optical fiber biosensor applications in real samples are enumerated.

  9. Survey of the 1998 optical biosensor literature.

    PubMed

    Myszka, D G

    1999-01-01

    The utilization of optical biosensors to study molecular interactions continues to expand. In 1998, 384 articles relating to the use of commercial biosensors were published in 130 different journals. While significant strides in new applications and methodology were made, a majority of the biosensor literature is of rather poor quality. Basic information about experimental conditions is often not presented and many publications fail to display the experimental data, bringing into question the credibility of the results. This review provides suggestions on how to collect, analyze and report biosensor data. PMID:10611648

  10. Zinc oxide interdigitated electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Sin L., L.; Arshad, M. K. Md.; Fathil, M. F. M.; Adzhri, R.; M. Nuzaihan M., N.; Ruslinda, A. R.; Gopinath, Subash C. B.; Hashim, U.

    2016-07-01

    In biosensors, zinc oxide (ZnO) thin film plays a crucial role in term of stability, sensitivity, biocompatibility and low cost. Interdigitated electrode (IDE) design is one of the device architecture in biosensor for label free, stability and sensitivity. In this paper, we discuss the fabrication of zinc oxide deposited on the IDE as a transducer for sensing of biomolecule. The formation of APTES had increase the performance of the surface functionalization..Furthermore we extend the discuss on the surface functionalization process which is utilized for probe attachment onto the surface of biosensor through surface immobilization process, thus enables the sensing of biomolecules for biosensor application.

  11. Biosensor based on magnetostrictive microcantilever

    NASA Astrophysics Data System (ADS)

    Li, Suiqiong; Orona, Lisa; Li, Zhimin; Cheng, Z.-Y.

    2006-02-01

    Magnetostrictive microcantilever (MSMC) as remote biosensor platform is reported. The mass sensitivity of the MSMCs is simulated and compared with the other microcantilevers. MSMCs with a thickness of 30-35μm and different lengths and widths were fabricated from the magnetostrictive metal glass coated with a copper layer by sputtering. The resonance behavior of the MSMCs was experimentally determined. It is experimentally found that the MSMCs work well in either air or liquid. For MSMCs operated in air, a Q value of more than 500 was obtained. For MSMCs operated in water, the Q value reaches more than 30. The application of a MSMC as a biosensor platform is demonstrated by in situ detection of the yeast cells in water using the MSMC sensor.

  12. An acquired distaste: Sugar discrimination by the larval parasitoid Microplitis croceipes (Hymenoptera: Braconidae) is affected by prior sugar exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As sugar quality feeding is very important in the lives of adult parasitoids, we examined several feeding responses of Microplitis croceipes to sugars commonly found in nectar. We first examined the relationship between feeding time and consumption of sucrose, glucose, fructose and maltose by Microp...

  13. Fluorescent protein-based cellular assays analyzed by laser-scanning microplate cytometry in 1536-well plate format.

    PubMed

    Auld, Douglas S; Johnson, Ronald L; Zhang, Ya-qin; Veith, Henrike; Jadhav, Ajit; Yasgar, Adam; Simeonov, Anton; Zheng, Wei; Martinez, Elisabeth D; Westwick, John K; Austin, Christopher P; Inglese, James

    2006-01-01

    Microtiter plate readers have evolved from photomultiplier and charged-coupled device-based readers, where a population-averaged signal is detected from each well, to microscope-based imaging systems, where cellular characteristics from individual cells are measured. For these systems, speed and ease of data analysis are inversely proportional to the amount of data collected from each well. Microplate laser cytometry is a technology compatible with a 1536-well plate format and capable of population distribution analysis. Microplate cytometers such as the Acumen Explorer can monitor up to four fluorescent signals from single objects in microtiter plates with densities as high as 1536 wells. These instruments can measure changes in fluorescent protein expression, cell shape, or simple cellular redistribution events such as cytoplasmic to nuclear translocation. To develop high-throughput screening applications using laser-scanning microplate cytometry, we used green fluorescent protein- and yellow fluorescent protein-expressing cell lines designed to measure diverse biological functions such as nuclear translocation, epigenetic signaling, and G protein-coupled receptor activation. This chapter illustrates the application of microplate laser cytometry to these assays in a manner that is suitable for screening large compound collections in high throughput. PMID:17110211

  14. Minimization of Between-well Sample Variance of Antifungal Activity Measurements Using a High-Throughput Screening Microplate Bioassay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of microplate bioassays, or broth microdilution assays, to measure the activity of biological and synthetic compounds against fungal pathogens has increased in recent years; this technique has been identified as the most promising in vitro bioassay for quantifying antifungal activity. Quant...

  15. Microplate-based active/inactive 1 screen for biomass degrading enzyme library purification and gene discovery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We present here a whole-cell and permeabilized E. coli cell 1' active/inactive microplate screen for ß-D-xylosidase, xylanase, endocellulase, and ferulic acid esterase enzyme activities which are critical for the enzymatic deconstruction of biomass for fuels and chemicals. Transformants from genomic...

  16. IDENTIFICATION OF ANTIFUNGAL COMPOUNDS IN A BIOLOGICAL CONTROL PRODUCT USING A MICROPLATE INHIBITION BIOASSAY AND MS ANALYSIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An inhibition assay was developed to quantify the antifungal activity of a solid state fermentation of Bacillus subtilis. Methanol extracts were tested against a spore solution of the fungal pathogen Fusarium oxysporum f. sp. melonis using a 96-well microplate bioassay. HPLC analysis of extracts s...

  17. The role of photoperiod and temperature in diapause induction of the endoparasitoid wasp, Microplitis mediator (Haliday) (Hymenoptera: Braconidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diapause in Microplitis mediator is manifested during the pupal stage and normally occurs during the winter season because of a photoperiodic response which is highly dependant on temperature. In the reported study, diapause was determine by photoperiod and mediated by temperature, which supports th...

  18. Plasmonic Nanostructures for Biosensor Applications

    NASA Astrophysics Data System (ADS)

    Gadde, Akshitha

    Improving the sensitivity of existing biosensors is an active research topic that cuts across several disciplines, including engineering and biology. Optical biosensors are the one of the most diverse class of biosensors which can be broadly categorized into two types based on the detection scheme: label-based and label-free detection. In label-based detection, the target bio-molecules are labeled with dyes or tags that fluoresce upon excitation, indicating the presence of target molecules. Label-based detection is highly-sensitive, capable of single molecule detection depending on the detector type used. One method of improving the sensitivity of label-based fluorescence detection is by enhancement of the emission of the labels by coupling them with metal nanostructures. This approach is referred as plasmon-enhanced fluorescence (PEF). PEF is achieved by increasing the electric field around the nano metal structures through plasmonics. This increased electric field improves the enhancement from the fluorophores which in turn improves the photon emission from the fluorophores which, in turn, improves the limit of detection. Biosensors taking advantage of the plasmonic properties of metal films and nanostructures have emerged an alternative, low-cost, high sensitivity method for detecting labeled DNA. Localized surface plasmon resonance (LSPR) sensors employing noble metal nanostructures have recently attracted considerable attention as a new class of plasmonic nanosensors. In this work, the design, fabrication and characterization of plasmonic nanostructures is carried out. Finite difference time domain (FDTD) simulations were performed using software from Lumerical Inc. to design a novel LSPR structure that exhibit resonance overlapping with the absorption and emission wavelengths of quantum dots (QD). Simulations of a composite Au/SiO2 nanopillars on silicon substrate were performed using FDTD software to show peak plasmonic enhancement at QD emission wavelength

  19. Optical biosensors for environmental monitoring

    SciTech Connect

    Tamiya, Eiichi

    1996-12-31

    Environmental assessment is important to evaluate the overall health and ecological impact of domestic and industrial wastes. Biosensors are kinds of analytical devices which consist of biomaterials and transducers. Photoluminescence of recombinant E. coli containing lux related genes were used as indicators of environmental pollutions. This paper deals with sensitive and rapid optical sensing systems for monitoring BOD (Biochemical Oxygen Demand), toxic compounds and mutagens.

  20. Biosensors for DNA sequence detection

    NASA Technical Reports Server (NTRS)

    Vercoutere, Wenonah; Akeson, Mark

    2002-01-01

    DNA biosensors are being developed as alternatives to conventional DNA microarrays. These devices couple signal transduction directly to sequence recognition. Some of the most sensitive and functional technologies use fibre optics or electrochemical sensors in combination with DNA hybridization. In a shift from sequence recognition by hybridization, two emerging single-molecule techniques read sequence composition using zero-mode waveguides or electrical impedance in nanoscale pores.

  1. Alginate cryogel based glucose biosensor

    NASA Astrophysics Data System (ADS)

    Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

    2016-02-01

    Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

  2. Biosensors based on nanomechanical systems.

    PubMed

    Tamayo, Javier; Kosaka, Priscila M; Ruz, José J; San Paulo, Álvaro; Calleja, Montserrat

    2013-02-01

    The advances in micro- and nanofabrication technologies enable the preparation of increasingly smaller mechanical transducers capable of detecting the forces, motion, mechanical properties and masses that emerge in biomolecular interactions and fundamental biological processes. Thus, biosensors based on nanomechanical systems have gained considerable relevance in the last decade. This review provides insight into the mechanical phenomena that occur in suspended mechanical structures when either biological adsorption or interactions take place on their surface. This review guides the reader through the parameters that change as a consequence of biomolecular adsorption: mass, surface stress, effective Young's modulus and viscoelasticity. The mathematical background needed to correctly interpret the output signals from nanomechanical biosensors is also outlined here. Other practical issues reviewed are the immobilization of biomolecular receptors on the surface of nanomechanical systems and methods to attain that in large arrays of sensors. We then describe some relevant realizations of biosensor devices based on nanomechanical systems that harness some of the mechanical effects cited above. We finally discuss the intrinsic detection limits of the devices and the limitation that arises from non-specific adsorption. PMID:23152052

  3. Modal interactions in primary and subharmonic resonant dynamics of imperfect microplates with geometric nonlinearities

    NASA Astrophysics Data System (ADS)

    Farokhi, Hamed; Ghayesh, Mergen H.

    2016-06-01

    This paper analyses the modal interactions in the nonlinear, size-dependent dynamics of geometrically imperfect microplates. Based on the modified couple stress theory, the equations of motion for the in-plane and out-of-plane motions are obtained employing the von Kármán plate theory as well as Kirchhoff's hypotheses by means of the Lagrange equations. The equations of motions are solved using the pseudo-arclength continuation technique and direct time-integration method. The system parameters are tuned to the values associated with modal interactions, and then nonlinear resonant responses and energy transfer are analysed. Nonlinear motion characteristics are shown in the form of frequency-response and force-response curves, time histories, phase-plane portraits, and fast Fourier transforms.

  4. Application of Imaging-Based Assays in Microplate Formats for High-Content Screening.

    PubMed

    Fogel, Adam I; Martin, Scott E; Hasson, Samuel A

    2016-01-01

    The use of multiparametric microscopy-based screens with automated analysis has enabled the large-scale study of biological phenomena that are currently not measurable by any other method. Collectively referred to as high-content screening (HCS), or high-content analysis (HCA), these methods rely on an expanding array of imaging hardware and software automation. Coupled with an ever-growing amount of diverse chemical matter and functional genomic tools, HCS has helped open the door to a new frontier of understanding cell biology through phenotype-driven screening. With the ability to interrogate biology on a cell-by-cell basis in highly parallel microplate-based platforms, the utility of HCS continues to grow as advancements are made in acquisition speed, model system complexity, data management, and analysis systems. This chapter uses an example of screening for genetic factors regulating mitochondrial quality control to exemplify the practical considerations in developing and executing high-content campaigns. PMID:27317002

  5. Antimicrobial susceptibility of standard strains of nontuberculous mycobacteria by microplate Alamar Blue assay.

    PubMed

    Li, Guilian; Lian, Lu-Lu; Wan, Li; Zhang, Jingrui; Zhao, Xiuqin; Jiang, Yi; Zhao, Li-Li; Liu, Haican; Wan, Kanglin

    2013-01-01

    In this study, 24 standard nontuberculous mycobacteria (NTM) species strains including 12 slowly growing mycobacteria strains and 12 rapidly growing mycobacteria strains were subjected to drug susceptibility testing using microplate Alamar Blue assay-based 7H9 broth. The most active antimicrobial agents against the 24 NTM strains were streptomycin, amikacin, the fluoroquinolones, and the tetracyclines. Mycobacterium chelonae, Mycobacterium abscessus, Mycobacterium bolletii, and Mycobacterium simiae are resistant to most antimicrobial agents. The susceptibility results of this study from 24 NTM standard strains can be referenced by clinicians before susceptibility testing for clinical isolates is performed or when conditions do not allow for susceptibility testing. The application of broth-based methods is recommended by the Clinical and Laboratory Standards Institute, and the documentation of the susceptibility patterns of standard strains of mycobacteria can improve the international standardization of susceptibility testing methods. PMID:24386332

  6. Rapid microplate, green method for high-throughput evaluation of vinegar acidity using thermal infrared enthalpimetry.

    PubMed

    Tischer, Bruna; Oliveira, Alessandra Stangherlin; Ferreira, Daniele de Freitas; Menezes, Cristiano Ragagnin; Duarte, Fábio Andrei; Wagner, Roger; Barin, Juliano Smanioto

    2017-01-15

    Infrared thermal imaging was combined with disposable microplates to perform enthalpimetric analysis using an infrared camera to monitor temperature without contact. The proposed thermal infrared enthalpimetry (TIE) method was used to determine the total, fixed and volatile acidities of vinegars. Sample preparation and analysis were performed in the same vessel, avoiding excessive sample handling and reducing energy expenditure by more than ten times. The results agreed with those of the conventional method for different kinds of vinegars, with values of 1.7%, and 2.3% for repeatability and intermediate precision, respectively. A linear calibration curve was obtained from 0.040 to 1.30molL(-1). The proposed method provided rapid results (within 10s) for four samples simultaneously, a sample throughput of up to 480 samples per hour. In addition, the method complies with at least eight of twelve recommendations for green analytical chemistry, making TIE a promising tool for routine vinegar analysis. PMID:27542445

  7. Modal interactions in primary and subharmonic resonant dynamics of imperfect microplates with geometric nonlinearities

    NASA Astrophysics Data System (ADS)

    Farokhi, Hamed; Ghayesh, Mergen H.

    2015-12-01

    This paper analyses the modal interactions in the nonlinear, size-dependent dynamics of geometrically imperfect microplates. Based on the modified couple stress theory, the equations of motion for the in-plane and out-of-plane motions are obtained employing the von Kármán plate theory as well as Kirchhoff's hypotheses by means of the Lagrange equations. The equations of motions are solved using the pseudo-arclength continuation technique and direct time-integration method. The system parameters are tuned to the values associated with modal interactions, and then nonlinear resonant responses and energy transfer are analysed. Nonlinear motion characteristics are shown in the form of frequency-response and force-response curves, time histories, phase-plane portraits, and fast Fourier transforms.

  8. Review of lignocellulolytic enzyme activity analyses and scale-down to microplate-based assays.

    PubMed

    Mansour, A A; Da Costa, A; Arnaud, T; Lu-Chau, T A; Fdz-Polanco, Maria; Moreira, M T; Cacho Rivero, J A

    2016-04-01

    With the increasing use of enzymes in environmental applications, there is a need for analytical methods adapted to large factorial experiments. Existing reference methods are chemical and labor intensive and unsuitable to analyze in parallel a large number of samples. Based on an extensive literature review and on experimental results, this work compares reference and microplate adapted methods to define the most adequate filter paper, carboxymethylcellulase, β-glucosidase and xylanase activity tests. In the adapted methods, the total reaction volume was reduced from 2.2-24.5 mL to 0.21-0.24 mL. Statistical analysis of the activities measured on enzyme mixtures by applying the 96-well plate reduced methods showed that they were not significantly different to the activities obtained with reference tests. PMID:26838452

  9. Highly Infectious Prions Generated by a Single Round of Microplate-Based Protein Misfolding Cyclic Amplification

    PubMed Central

    Moudjou, Mohammed; Sibille, Pierre; Fichet, Guillaume; Reine, Fabienne; Chapuis, Jérôme; Herzog, Laetitia; Jaumain, Emilie; Laferrière, Florent; Richard, Charles-Adrien; Laude, Hubert; Andréoletti, Olivier; Rezaei, Human; Béringue, Vincent

    2013-01-01

    ABSTRACT Measurements of the presence of prions in biological tissues or fluids rely more and more on cell-free assays. Although protein misfolding cyclic amplification (PMCA) has emerged as a valuable, sensitive tool, it is currently hampered by its lack of robustness and rapidity for high-throughput purposes. Here, we made a number of improvements making it possible to amplify the maximum levels of scrapie prions in a single 48-h round and in a microplate format. The amplification rates and the infectious titer of the PMCA-formed prions appeared similar to those derived from the in vivo laboratory bioassays. This enhanced technique also amplified efficiently prions from different species, including those responsible for human variant Creutzfeldt-Jakob disease. This new format should help in developing ultrasensitive, high-throughput prion assays for cognitive, diagnostic, and therapeutic applications. PMID:24381300

  10. Mismatch oxidation assay: detection of DNA mutations using a standard UV/Vis microplate reader.

    PubMed

    Tabone, Tania; Sallmann, Georgina; Cotton, Richard G H

    2009-01-01

    Simple, low-cost mutation detection assays that are suitable for low-throughput analysis are essential for diagnostic applications where the causative mutation may be different in every family. The mismatch oxidation assay is a simple optical absorbance assay to detect nucleotide substitutions, insertions, and deletions in heteroduplex DNA. The method relies on detecting the oxidative modification products of mismatched thymine and cytosine bases by potassium permanganate as it is reduced to manganese dioxide. This approach, unlike other methods commonly used to detect sequence variants, does not require costly labeled probes or primers, toxic chemicals, or a time-consuming electrophoretic separation step. The oxidation rate, and hence the presence of a sequence variant, is detected by measuring the formation of the potassium permanganate reduction product (hypomanganate diester), which absorbs at the 420-nm visible wavelength, using a standard UV/vis microplate reader. PMID:19768598

  11. Missing mass effect in biosensor's QCM applications.

    PubMed

    Voinova, M V; Jonson, M; Kasemo, B

    2002-10-01

    Nowadays, liquid applications of quartz crystal microbalance (QCM) opened a way for in situ studies of proteins, vesicles and cells adsorbed from the solution onto the QCM surface. The sensitivity of QCM to the viscoelasticity of the adsorbed biomaterial can be a reason of the experimentally observed deviation from a linear dependence of QCM resonant frequency on mass deposition (the so-called Sauerbrey relation) and can limit its application for biosensoring. Presented here rigorous theoretical analysis explains the deviation from ideal mass response of soft overlayers in the contact with liquid. The fundamental result of the theory is the analog of Sauerbrey relation for layered viscous/viscoelastic medium which can be exploited for the correct physical interpretation of QCM experimental data in biofluids, in particular for measurements of the 'true' surface mass of adsorbed biomolecular films. We predict a new physical effect 'missing mass' of the sample in liquid phase measurements and compare the results given by our theory with QCM measurements on supported membranes. PMID:12243901

  12. Adaptation of Microplate-based Respirometry for Hippocampal Slices and Analysis of Respiratory Capacity

    PubMed Central

    Schuh, Rosemary A.; Clerc, Pascaline; Hwang, Hyehyun; Mehrabian, Zara; Bittman, Kevin; Chen, Hegang; Polster, Brian M.

    2011-01-01

    Multiple neurodegenerative disorders are associated with altered mitochondrial bioenergetics. Although mitochondrial O2 consumption is frequently measured in isolated mitochondria, isolated synaptic nerve terminals (synaptosomes), or cultured cells, the absence of mature brain circuitry is a remaining limitation. Here we describe the development of a method that adapts the Seahorse Extracellular Flux Analyzer (XF24) for the microplate-based measurement of hippocampal slice O2 consumption. As a first evaluation of the technique, we compared whole slice bioenergetics to previous measurements made with synaptosomes or cultured neurons. We found that mitochondrial respiratory capacity and O2 consumption coupled to ATP synthesis could be estimated in cultured or acute hippocampal slices with preserved neural architecture. Mouse organotypic hippocampal slices oxidizing glucose displayed mitochondrial O2 consumption that was well-coupled, as determined by the sensitivity to the ATP synthase inhibitor oligomycin. However stimulation of respiration by uncoupler was modest (<120% of basal respiration) compared to previous measurements in cells or synaptosomes, although enhanced slightly (to ~150% of basal respiration) by the acute addition of the mitochondrial complex I-linked substrate pyruvate. These findings suggest a high basal utilization of respiratory capacity in slices and a limitation of glucose-derived substrate for maximal respiration. The improved throughput of microplate-based hippocampal respirometry over traditional O2 electrode-based methods is conducive to neuroprotective drug screening. When coupled with cell type-specific pharmacology or genetic manipulations, the ability to efficiently measure O2 consumption from whole slices should advance our understanding of mitochondrial roles in physiology and neuropathology. PMID:21520220

  13. Deformation driven by subduction and microplate collision: Geodynamics of Cook Inlet basin, Alaska

    USGS Publications Warehouse

    Bruhn, R.L.; Haeussler, P.J.

    2006-01-01

    Late Neogene and younger deformation in Cook Inlet basin is caused by dextral transpression in the plate margin of south-central Alaska. Collision and subduction of the Yakutat microplate at the northeastern end of the Aleutian subduction zone is driving the accretionary complex of the Chugach and Kenai Mountains toward the Alaska Range on the opposite side of the basin. This deformation creates belts of fault-cored anticlines that are prolific traps of hydrocarbons and are also potential sources for damaging earthquakes. The faults dip steeply, extend into the Mesozoic basement beneath the Tertiary basin fill, and form conjugate flower structures at some localities. Comparing the geometry of the natural faults and folds with analog models created in a sandbox deformation apparatus suggests that some of the faults accommodate significant dextral as well as reverse-slip motion. We develop a tectonic model in which dextral shearing and horizontal shortening of the basin is driven by microplate collision with an additional component of thrust-type strain caused by plate subduction. This model predicts temporally fluctuating stress fields that are coupled to the recurrence intervals of large-magnitude subduction zone earthquakes. The maximum principal compressive stress is oriented east-southeast to east-northeast with nearly vertical least compressive stress when the basin's lithosphere is mostly decoupled from the underlying subduction megathrust. This stress tensor is compatible with principal stresses inferred from focal mechanisms of earthquakes that occur within the crust beneath Cook Inlet basin. Locking of the megathrust between great magnitude earthquakes may cause the maximum principal compressive stress to rotate toward the northwest. Moderate dipping faults that strike north to northeast may be optimally oriented for rupture in the ambient stress field, but steeply dipping faults within the cores of some anticlines are unfavorably oriented with respect to

  14. Crustal Structure of the Yakutat Microplate: Constraints from STEEP Wide-angle Seismic Data

    NASA Astrophysics Data System (ADS)

    Christeson, G. L.; van Avendonk, H.; Gulick, S. P.; Worthington, L.; Pavlis, T.

    2008-12-01

    In Fall 2008 we will conduct a seismic program focusing on the Yakutat microplate. As part of this study we plan to acquire two wide-angle profiles: an onshore-offshore northwest-southeast oriented profile extending from the Bering glacier onto the continental shelf and across the Dangerous River Zone, and an offshore northeast-southwest oriented profile extending from the ocean basin across the Transition fault and into Yakutat Bay. The sound source will be the R/V Langseth's tuned 6600 cu. in., 36 air gun array. Ocean bottom seismometers will be positioned at ~15 km spacing, and Texan seismometers at 1-4 km spacing across the Bering Glacier. Coincident deep-penetrating seismic reflection data will be acquired on the marine portion of both profiles using a 8-km, 640-channel solid hydrophone streamer. Existing models for the Yakutat microplate disagree as to whether it is a continental fragment attached to normal oceanic crust or an oceanic plateau, and if the deep structure changes from west to east across the Dangerous River Zone. In the continental fragment model uplift is concentrated along crustal-scale thrust faulting at the ocean crust boundary (Dangerous River Zone?) resulting in focused and rapid erosion. In the oceanic plateau model more distributed, regional uplift is expected which will produce widespread exhumation with net erosion potentially coupled with glacial cycles. Thus distinguishing between these models, which we expect to accomplish with our planned seismic program, is vital for linking tectonics to erosion on both spatial and temporal scales.

  15. Validation and characterization of optical redox ratio measurements with a microplate reader in breast cancer cells

    NASA Astrophysics Data System (ADS)

    Cannon, Taylor M.; Shah, Amy T.; Skala, Melissa C.

    2015-02-01

    There is a need for accurate, high-throughput measures to gauge the efficacy of potential drugs in living cells. Metabolism is an early marker of drug response in cells, and NADH and FAD are autofluorescent cellular metabolic coenzymes that can be non-invasively monitored using optical techniques. Relative rates of glycolysis and oxidative phosphorylation in a cell are quantified by the redox ratio, defined as the autofluorescence intensity of NADH divided by that of FAD. Microplate readers are high-throughput instruments that can rapidly measure NADH and FAD autofluorescence intensities for hundreds of wells, and are capable of identifying receptor status and resolving drug response in breast cancer cell lines. This study tests the accuracy and repeatability of plate reader experiments measuring the redox ratio in breast cancer cell lines. NADH and FAD fluorescence levels remained constant over the course of multiple measurements (p<0.1), ruling out the incidence of photobleaching. The contribution of media to background fluorescence signal was also investigated. Media fluorescence levels for both coenzymes were significantly lower (p<0.0001) than those from wells containing cells, and replacing the media with saline resulted in the same redox ratio trends among cell lines as initial measurements with media. Following treatment with carbonyl cyanide p-fluorodeoxyphenylhydrazone (FCCP), an oxidative phosphorylation inhibitor, the redox ratio decreased (p<0.05), validating NADH and FAD as the primary fluorescence sources. These findings verify that autofluorescence measurements taken by microplate readers accurately and reliably characterize NADH and FAD fluorescence, validating their promise in the areas of metabolic monitoring and drug development.

  16. Two Variants of a High-Throughput Fluorescent Microplate Assay of Polysaccharide Endotransglycosylases.

    PubMed

    Kováčová, Kristína; Farkaš, Vladimír

    2016-04-01

    Polysaccharide endotransglycosylases (PETs) are the cell wall-modifying enzymes of fungi and plants. They catalyze random endo-splitting of the polysaccharide donor molecule and transfer of the newly formed reducing sugar residue to the nonreducing end of an acceptor molecule which can be a polysaccharide or an oligosaccharide. Owing to their important role in the cell wall formation, the inhibition of PETs represents an attractive strategy in the fight against fungal infections. We have elaborated two variants of a versatile high-throughput microplate fluorimetric assay that could be used for effective identification of PETs and screening of their inhibitors. Both assays use the respective polysaccharides as the donors and sulforhodamine-labeled oligosaccharides as the acceptors but differ from each other by mode of how the labeled polysaccharide products of transglycosylation are separated from the unreacted oligosaccharide acceptors. In the first variant, the reactions take place in a layer of agar gel laid on the bottoms of the wells of a microtitration plate. After the reaction, the high-Mr transglycosylation products are precipitated with 66 % ethanol and retained within the gel while the low-Mr products and the unreacted acceptors are washed out. In the second variant, the donor polysaccharides are adsorbed to the surface of a microplate well and remain adsorbed there also after becoming labeled in the course of the transglycosylation reaction whereas the unused low-Mr acceptors are washed out. As a proof of versatility, assays of heterologously expressed transglycosylases ScGas1, ScCrh1, and ScCrh2 from the yeast Saccharomyces cerevisiae, CaPhr1 and CaPhr2 from Candida albicans, and of a plant xyloglucan endotransglycosylase (XET) are demonstrated. PMID:26754421

  17. Nanomaterials based biosensors for cancer biomarker detection

    NASA Astrophysics Data System (ADS)

    Malhotra, Bansi D.; Kumar, Saurabh; Mouli Pandey, Chandra

    2016-04-01

    Biosensors have enormous potential to contribute to the evolution of new molecular diagnostic techniques for patients suffering with cancerous diseases. A major obstacle preventing faster development of biosensors pertains to the fact that cancer is a highly complex set of diseases. The oncologists currently rely on a few biomarkers and histological characterization of tumors. Some of the signatures include epigenetic and genetic markers, protein profiles, changes in gene expression, and post-translational modifications of proteins. These molecular signatures offer new opportunities for development of biosensors for cancer detection. In this context, conducting paper has recently been found to play an important role towards the fabrication of a biosensor for cancer biomarker detection. In this paper we will focus on results of some of the recent studies obtained in our laboratories relating to fabrication and application of nanomaterial modified paper based biosensors for cancer biomarker detection.

  18. Renewable Surface Biosensors with Optical Detection

    SciTech Connect

    Bruckner-Lea, Cindy J.; Ackerman, Eric J.; Dockendorff, Brian P.; Holman, David A.; Grate, Jay W.

    2001-04-30

    One major challenge in the development of biosensors is the limited lifetime of a chemically selective surface that includes biomolecules. Renewable surface biosensors address this issue by using fresh aliquots of derivatized microbeads for each analysis. The analyte detection can then occur on the microbeads, or downstream from the microbeads. In this paper, we will describe two types of renewable surface biosensors. The first renewable biosensor system includes on-column optical detection for monitoring the binding of biomolecules onto protein or DNA-derivatized Sepharose beads. The second renewable biosensor system includes detection downstream from the microparticles and is based on the use of derivatized magnetic particles for selective binding. The magnetic particles are fluidically captured and released in a sequential injection system to allow the automation of an Enzyme Linked ImmunoSorbent Assay.

  19. Renewable Surface Biosensors With Optical Detection

    SciTech Connect

    Bruckner-Lea, Cynthia J.; Ackerman, Eric J.; Dockendorff, Brian P.; Holman, David A.; Grate, Jay W.

    2001-12-01

    One major challenge in the development of biosensors is the limited lifetime of a chemically selective surface that includes biomolecules. Renewable surface biosensors address this issue by using fresh aliquots of derivatized microbeads for each analysis. The analyte detection can then occur on the microbeads, or downstream from the microbeads. In this paper, we will describe two types of renewable surface biosensors. The first renewable biosensor system includes on-column optical detection for monitoring the binding of biomolecules onto protein or DNA-derivatized Sepharose beads. The second renewable biosensor system includes detection downstream from the microparticles and is based on the use of derivatized magnetic particles for selective binding. The magnetic particles are fluidically captured and released in a sequential injection system to allow the automation of an Enzyme Linked ImmunoSorbent Assay.

  20. A creatinine biosensor based on admittance measurement

    NASA Astrophysics Data System (ADS)

    Ching, Congo Tak-Shing; Sun, Tai-Ping; Jheng, Deng-Yun; Tsai, Hou-Wei; Shieh, Hsiu-Li

    2015-08-01

    Regular check of blood creatinine level is very important as it is a measurement of renal function. Therefore, the objective of this study is to develop a simple and reliable creatinine biosensor based on admittance measurement for precise determination of creatinine. The creatinine biosensor was fabricated with creatinine deiminase immobilized on screen-printed carbon electrodes. Admittance measurement at a specific frequency ranges (22.80 - 84.71 Hz) showed that the biosensor has an excellent linear (r2 > 0.95) response range (50 - 250 uM), which covers the normal physiological and pathological ranges of blood creatinine levels. Intraclass correlation coefficient (ICC) showed that the biosensor has excellent reliability and validity (ICC = 0.98). In conclusion, a simple and reliable creatinine biosensor was developed and it is capable of precisely determining blood creatinine levels in both the normal physiological and pathological ranges.

  1. Biosensoric potential of microbial fuel cells.

    PubMed

    Schneider, György; Kovács, Tamás; Rákhely, Gábor; Czeller, Miklós

    2016-08-01

    Recent progress in microbial fuel cell (MFC) technology has highlighted the potential of these devices to be used as biosensors. The advantages of MFC-based biosensors are that they are phenotypic and can function in either assay- or flow-through formats. These features make them appropriate for contiguous on-line monitoring in laboratories and for in-field applications. The selectivity of an MFC biosensor depends on the applied microorganisms in the anodic compartment where electron transfer (ET) between the artificial surface (anode) and bacterium occurs. This process strongly determines the internal resistance of the sensoric system and thus influences signal outcome and response time. Despite their beneficial characteristics, the number of MFC-based biosensoric applications has been limited until now. The aim of this mini-review is to turn attention to the biosensoric potential of MFCs by summarizing ET mechanisms on which recently established and future sensoric devices are based. PMID:27401925

  2. Orientational nanoparticle assemblies and biosensors.

    PubMed

    Ma, Wei; Xu, Liguang; Wang, Libing; Kuang, Hua; Xu, Chuanlai

    2016-05-15

    Assemblies of nanoparticles (NPs) have regional correlated properties with new features compared to individual NPs or random aggregates. The orientational NP assembly contributes greatly to the collective interaction of individual NPs with geometrical dependence. Therefore, orientational NPs assembly techniques have emerged as promising tools for controlling inorganic NPs spatial structures with enhanced interesting properties. The research fields of orientational NP assembly have developed rapidly with characteristics related to the different methods used, including chemical, physical and biological techniques. The current and potential applications, important challenges remain to be investigated. An overview of recent developments in orientational NPs assemblies, the multiple strategies, biosensors and challenges will be discussed in this review. PMID:26708241

  3. Microfabricated silicon biosensors for microphysiometry

    NASA Technical Reports Server (NTRS)

    Bousse, L. J.; Libby, J. M.; Parce, J. W.

    1993-01-01

    Microphysiometers are biosensor devices that measure the metabolic rate of living cells by detecting the rate of extracellular acidification caused by a small number of cells. The cells are entrapped in a microvolume chamber, whose bottom surface is a silicon sensor chip. In a further miniaturization step, we have recently fabricated multichannel flow-through chips that will allow greater throughput and multiplicity. Microphysiometer technology can be applied to the detection of microorganisms. We describe the sensitive detection of bacteria and yeast. Further applications of microphysiometry to the characterization of microorganisms can be anticipated.

  4. Developing Highly Sensitive Micro-Biosensors for in-situ Monitoring Mercury and Chromium(IV) Contaminants by Genetically-evolving and Computer-designing Metal-binding Proteins

    SciTech Connect

    Wang, Qinghong; Fang, Xiangdong; Goddard, William

    2013-10-17

    Mercury has been well known as an environmental pollutant to the environment and to cause serious effects on human health for several decades. To effectively control mercury pollution and reduce mercury damages, the sensitive determination of mercury is essential. Currently, many different types of sensor-based assays have been developed, while the whole-cell biosensor has been gaining increasingly attentions due to its easy reproducibility and the possibility to greatly reduce the cost. However, significant improvements on the specificity, sensitivity, stability and simplicity of the whole-cell biosensor are still needed prior to its eventual commercialization. Sponsored by US Department of Energy under the contract agreement DE-FG02-07ER64410, we applied the special synthetic biology and directed evolution strategies to improve the effectiveness and performance of whole-cell biosensors. We have constructed different whole-cell biosensors for the mercuric ion and methylmercury detection with metalloregulator MerR, fluorescent protein mCherry and organomercurial lyase MerB. By introducing the mercuric transporter MerT, we were able to increase the detection sensitivity of whole-cell biosensors by at least one fold. By introducing the bio-amplification genetic circuit based on the gene cascade expression system of PRM-cI from bacteriophage l and Pm-XylS2 from Pseudomonas putida, we have increased the detection sensitivity of whole-cell biosensors by 1~2 folds in our tested conditions. With the directed evolution of MerR and subsequent high-throughput screening via color assay and microplate screening, we have dramatically increased the detection sensitivity by up to 10 folds at low concentration of mercury (II) of 1-10nM. Structural modeling and computational analysis of the mutated MerR showed that many mutations could cause the change of a loop to helix, which could be responsible for the increased mercury sensitivity.

  5. Nanotubes, Nanowires, and Nanocantilevers in Biosensor Development

    SciTech Connect

    Wang, Jun; Liu, Guodong; Lin, Yuehe

    2007-03-08

    In this chapter, the reviews on biosensor development based on 1-D nanomaterials, CNTs, semiconducting nanowires, and some cantilevers will be introduced. The emphasis of this review will be placed on CNTs and electrochemical/electronic biosensor developments. Section 2 of this chapter gives a detailed description of carbon nanotubes-based biosensor development, from fabrication of carbon nanotubes, the strategies for construction of carbon nanotube based biosensors to their bioapplications. In the section of the applications of CNTs based biosensors, various detection principles, e. g. electrochemical, electronic, and optical method, and their applications are reviewed in detail. Section 3 introduces the method for synthesis of semiconducting nanowires, e.g. silicon nanowires, conducting polymer nanowires and metal oxide nanowires and their applications in DNA and proteins sensing. Section 4 simply describes the development for nanocantilevers based biosensors and their application in DNA and protein diagnosis. Each section starts from a brief introduction and then goes into details. Finally in the Conclusion section, the development of 1-D nanomaterials based biosensor development is summarized.

  6. Slow light Mach-Zehnder interferometer as label-free biosensor with scalable sensitivity

    DOE PAGESBeta

    Qin, Kun; Hu, Shuren; Retterer, Scott T.; Kravchenko, Ivan I.; Weiss, Sharon M.

    2016-02-05

    Our design, fabrication, and characterization of a label-free Mach–Zehnder interferometer (MZI) optical biosensor that incorporates a highly dispersive one-dimensional (1D) photonic crystal in one arm are presented. The sensitivity of this slow light MZI-based sensor scales with the length of the slow light photonic crystal region. The numerically simulated sensitivity of a MZI sensor with a 16 μm long slow light region is 115,000 rad/RIU-cm, which is sevenfold higher than traditional MZI biosensors with millimeter-length sensing regions. Moreover, the experimental bulk refractive index detection sensitivity of 84,000 rad/RIU-cm is realized and nucleic acid detection is also demonstrated.

  7. Biosensor Approach to Psychopathology Classification

    PubMed Central

    Koshelev, Misha; Lohrenz, Terry; Vannucci, Marina; Montague, P. Read

    2010-01-01

    We used a multi-round, two-party exchange game in which a healthy subject played a subject diagnosed with a DSM-IV (Diagnostic and Statistics Manual-IV) disorder, and applied a Bayesian clustering approach to the behavior exhibited by the healthy subject. The goal was to characterize quantitatively the style of play elicited in the healthy subject (the proposer) by their DSM-diagnosed partner (the responder). The approach exploits the dynamics of the behavior elicited in the healthy proposer as a biosensor for cognitive features that characterize the psychopathology group at the other side of the interaction. Using a large cohort of subjects (n = 574), we found statistically significant clustering of proposers' behavior overlapping with a range of DSM-IV disorders including autism spectrum disorder, borderline personality disorder, attention deficit hyperactivity disorder, and major depressive disorder. To further validate these results, we developed a computer agent to replace the human subject in the proposer role (the biosensor) and show that it can also detect these same four DSM-defined disorders. These results suggest that the highly developed social sensitivities that humans bring to a two-party social exchange can be exploited and automated to detect important psychopathologies, using an interpersonal behavioral probe not directly related to the defining diagnostic criteria. PMID:20975934

  8. Comparative advantages of mechanical biosensors

    PubMed Central

    Arlett, J.L.; Myers, E.B.; Roukes, M.L.

    2013-01-01

    Mechanical interactions are fundamental to biology. Mechanical forces of chemical origin determine motility and adhesion on the cellular scale, and govern transport and affinity on the molecular scale. Biological sensing in the mechanical domain provides unique opportunities to measure forces, displacements and mass changes from cellular and subcellular processes. Nanomechanical systems are particularly well matched in size with molecular interactions, and provide a basis for biological probes with single-molecule sensitivity. Here we review micro- and nanoscale biosensors, with a particular focus on fast mechanical biosensing in fluid by mass- and force-based methods, and the challenges presented by non-specific interactions. We explain the general issues that will be critical to the success of any type of next-generation mechanical biosensor, such as the need to improve intrinsic device performance, fabrication reproducibility and system integration. We also discuss the need for a greater understanding of analyte–sensor interactions on the nanoscale and of stochastic processes in the sensing environment. PMID:21441911

  9. Electrochemical application of DNA biosensors

    NASA Astrophysics Data System (ADS)

    Mascini, M.; Lucarelli, F.; Palchetti, I.; Marrazza, G.

    2001-09-01

    Disposable electrochemical DNA-based biosensors are reviewed; they have been used for the determination of low- molecular weight compounds with affinity for nucleic acids and for the detection of hybridization reaction. The first application is related to the molecular interaction between surface-linked DNA and pollutants or drugs, in order to develop a simple device for rapid screening of toxic compounds. The determination of such compounds was measured by their effect simple device for rapid screening of toxic compounds. The determination of such compounds was measured by their effect on the oxidation signal of the guanine peak of calf thymus DNA immobilized on the electrode surface and investigated by chronopotentiometric or voltammetric analysis. Applicability to river and wastewater sample is demonstrated. Moreover, disposable electrochemical sensors for the detection of a specific sequence of DNA were realized by immobilizing synthetic single-stranded oligonucleotides onto a graphite screen-printed electrode. The probes because hybridized with different concentrations of complementary sequences present in the sample. The hybrids formed on the electrode surface were evaluated by chronopotentiometric analysis using daunomycin as the indicator of the hybridization reaction. The hybridization was also performed using real samples. Application to apolipoprotein E is described, in this case samples have to be amplified by PCR and then analyzed by the DNA biosensor. The extension of such procedures to samples of environmental interest or to contamination of food is discussed.

  10. Development of Magnetization Measurement Devices Using Micro-dc-SQUIDs and a Sr_2RuO_4 Microplate

    NASA Astrophysics Data System (ADS)

    Nago, Y.; Shinozaki, T.; Tsuchiya, S.; Ishiguro, R.; Kashiwaya, H.; Kashiwaya, S.; Nomura, S.; Kono, K.; Takayanagi, H.; Maeno, Y.

    2016-05-01

    We developed high-sensitivity magnetization measurement devices composed of micro-dc-SQUIDs and a superconducting Sr_2RuO_4 microplate, aiming to investigate novel magnetic properties related to a spin-triplet chiral p-wave superconductor with a mesoscopic size. Micron-sized dc-SQUID was fabricated by thin Al electrodes, and the SQUID structure was improved to prevent magnetic fluxes from intruding into SQUID electrodes. A Sr_2RuO_4 superconducting microplate was fabricated into the size as small as the SQUID loop using a focused ion beam and directly mounted on the SQUID with precise positioning for high-sensitivity magnetization measurements. In the preliminary magnetization measurements of this device, we observed vortices trapped into the plate and thus the lower critical field. The improved magnetization measurement device developed to exclude undesirable flux intrusion successfully enabled high-sensitivity detection of quantized vortex.

  11. Microplate MPN-enumeration of monocyclic- and dicyclic-aromatic hydrocarbon degraders via substrate phase-partitioning.

    PubMed

    Johnsen, Anders R; Henriksen, Sidsel

    2009-07-01

    The high aqueous solubility of monoaromatic and some diaromatic oil components may hinder classical growth-based MPN enumeration of bacterial mono- and di-aromatics degraders because these aromatics are toxic in high concentrations. We developed a microplate MPN method for the enumeration of toluene-, xylene-, naphthalene-, biphenyl- and benzothiophene-degraders on the basis of phase-partitioning of substrate between a biologically inert organic phase and an aqueous mineral salt medium. This way, it was possible to maintain non-toxic, aqueous concentrations in the microplate wells. Depletion of aqueous aromatics by growth of the degraders was prevented by the continuous solubilization of aromatics from the silicone phase. The method was validated by MPN enumerating degrader cultures both with phase-partitioned aromatics and with tryptic soy broth as carbon sources. The applicability of the method was demonstrated by MPN-enumerating mono- and di-aromatic degraders in soils of varying hydrocarbon pre-exposure. PMID:19043785

  12. Early Lung Cancer Diagnosis by Biosensors

    PubMed Central

    Zhang, Yuqian; Yang, Dongliang; Weng, Lixing; Wang, Lianhui

    2013-01-01

    Lung cancer causes an extreme threat to human health, and the mortality rate due to lung cancer has not decreased during the last decade. Prognosis or early diagnosis could help reduce the mortality rate. If microRNA and tumor-associated antigens (TAAs), as well as the corresponding autoantibodies, can be detected prior to clinical diagnosis, such high sensitivity of biosensors makes the early diagnosis and prognosis of cancer realizable. This review provides an overview of tumor-associated biomarker identifying methods and the biosensor technology available today. Laboratorial researches utilizing biosensors for early lung cancer diagnosis will be highlighted. PMID:23892596

  13. Remote sensing using an airborne biosensor

    SciTech Connect

    Ligler, F.S.; Anderson, G.P.; Davidson, P.T.; Stenger, D.A.; Ives, J.T.; King, K.D.; Page, G.; Whelan, J.P.

    1998-08-15

    There is no current method for remote identification of aerosolized bacteria. In particular, such a capability is required to warn of a biological warfare attack prior to human exposure. A fiber optic biosensor, capable of running four simultaneous immunoassays, was integrated with an automated fluidics unit, a cyclone-type air sampler, a radio transceiver, and batteries on a small, remotely piloted airplane capable of carrying a 4.5-kg payload. The biosensor system was able to collect aerosolized bacteria in flight, identify them, and transmit the data to the operator on the ground. The results demonstrate the feasibility of integrating a biosensor into a portable, remotely operated system for environmental analysis.

  14. A New Look at Spreading in Iceland: Propagating Rifts, Migrating Transform Faults, and Microplate Tectonics

    NASA Astrophysics Data System (ADS)

    Karson, J.; Horst, A. J.; Nanfito, A.

    2011-12-01

    Iceland has long been used as an analog for studies of seafloor spreading. Despite its thick (~25 km) oceanic crust and subaerial lavas, many features associated with accretion along mid-ocean ridge spreading centers, and the processes that generate them, are well represented in the actively spreading Neovolcanic Zone and deeply glaciated Tertiary crust that flanks it. Integrated results of structural and geodetic studies show that the plate boundary zone on Iceland is a complex array of linked structures bounding major crustal blocks or microplates, similar to oceanic microplates. Major rift zones propagate N and S from the hotspot centered beneath the Vatnajökull icecap in SE central Iceland. The southern propagator has extended southward beyond the South Iceland Seismic Zone transform fault to the Westman Islands, resulting in abandonment of the Eastern Rift Zone. Continued propagation may cause abandonment of the Reykjanes Ridge. The northern propagator is linked to the southern end of the receding Kolbeinsey Ridge to the north. The NNW-trending Kerlingar Pseudo-fault bounds the propagator system to the E. The Tjörnes Transform Fault links the propagator tip to the Kolbeinsey Ridge and appears to be migrating northward in incremental steps, leaving a swath of deformed crustal blocks in its wake. Block rotations, concentrated mainly to the west of the propagators, are clockwise to the N of the hotspot and counter-clockwise to the S, possibly resulting in a component of NS divergence across EW-oriented rift zones. These rotations may help accommodate adjustments of the plate boundary zone to the relative movements of the N American and Eurasian plates. The rotated crustal blocks are composed of highly anisotropic crust with rift-parallel internal fabric generated by spreading processes. Block rotations result in reactivation of spreading-related faults as major rift-parallel, strike-slip faults. Structural details found in Iceland can help provide information

  15. Microplitis demolitor Bracovirus Proviral Loci and Clustered Replication Genes Exhibit Distinct DNA Amplification Patterns during Replication

    PubMed Central

    Simmonds, Tyler J.; Thomas, Sarah A.; Strand, Michael R.

    2015-01-01

    ABSTRACT Polydnaviruses are large, double-stranded DNA viruses that are beneficial symbionts of parasitoid wasps. Polydnaviruses in the genus Bracovirus (BVs) persist in wasps as proviruses, and their genomes consist of two functional components referred to as proviral segments and nudivirus-like genes. Prior studies established that the DNA domains where proviral segments reside are amplified during replication and that segments within amplified loci are circularized before packaging into nucleocapsids. One DNA domain where nudivirus-like genes are located is also amplified but never packaged into virions. We recently sequenced the genome of the braconid Microplitis demolitor, which carries M. demolitor bracovirus (MdBV). Here, we took advantage of this resource to characterize the DNAs that are amplified during MdBV replication using a combination of Illumina and Pacific Biosciences sequencing approaches. The results showed that specific nucleotide sites identify the boundaries of amplification for proviral loci. Surprisingly, however, amplification of loci 3, 4, 6, and 8 produced head-to-tail concatemeric intermediates; loci 1, 2, and 5 produced head-to-head/tail-to-tail concatemers; and locus 7 yielded no identified concatemers. Sequence differences at amplification junctions correlated with the types of amplification intermediates the loci produced, while concatemer processing gave rise to the circularized DNAs that are packaged into nucleocapsids. The MdBV nudivirus-like gene cluster was also amplified, albeit more weakly than most proviral loci and with nondiscrete boundaries. Overall, the MdBV genome exhibited three patterns of DNA amplification during replication. Our data also suggest that PacBio sequencing could be useful in studying the replication intermediates produced by other DNA viruses. IMPORTANCE Polydnaviruses are of fundamental interest because they provide a novel example of viruses evolving into beneficial symbionts. All polydnaviruses are

  16. Cellphone-based hand-held microplate reader for point-of-care ELISA testing (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Berg, Brandon; Cortazar, Bingen; Tseng, Derek; Ozkan, Haydar; Feng, Steve; Wei, Qingshan; Chan, Raymond Y.; Burbano, Jordi; Farooqui, Qamar; Lewinski, Michael; Di Carlo, Dino; Garner, Omai B.; Ozcan, Aydogan

    2016-03-01

    Enzyme-linked immunosorbent assay (ELISA) in a microplate format has been a gold standard first-line clinical test for diagnosis of various diseases including infectious diseases. However, this technology requires a relatively large and expensive multi-well scanning spectrophotometer to read and quantify the signal from each well, hindering its implementation in resource-limited-settings. Here, we demonstrate a cost-effective and handheld smartphone-based colorimetric microplate reader for rapid digitization and quantification of immunoserology-related ELISA tests in a conventional 96-well plate format at the point of care (POC). This device consists of a bundle of 96 optical fibers to collect the transmitted light from each well of the microplate and direct all the transmission signals from the wells onto the camera of the mobile-phone. Captured images are then transmitted to a remote server through a custom-designed app, and both quantitative and qualitative diagnostic results are returned back to the user within ~1 minute per 96-well plate by using a machine learning algorithm. We tested this mobile-phone based micro-plate reader in a clinical microbiology lab using FDA-approved mumps IgG, measles IgG, and herpes simplex virus IgG (HSV-1 and HSV-2) ELISA tests on 1138 remnant patient samples (roughly 50% training and 50% testing), and achieved an overall accuracy of ~99% or higher for each ELISA test. This handheld and cost-effective platform could be immediately useful for large-scale vaccination monitoring in low-infrastructure settings, and also for other high-throughput disease screening applications at POC.

  17. Development of quantum dots-based biosensor towards on-farm detection of subclinical ketosis.

    PubMed

    Weng, Xuan; Chen, Longyan; Neethirajan, Suresh; Duffield, Todd

    2015-10-15

    Early detection of dairy animal health issues allows the producer or veterinarian to intervene before the animals' production levels, or even survival, is threatened. An increased concentration of β-hydroxybutyrate (βHBA) is a key biomarker for diagnosis of subclinical ketosis (SCK), and provides information on the health stress in cows well before any external symptoms are observable. In this study, quantum dots (QDs) modified with cofactor nicotinamide adenine dinucleotide (NAD(+)) were prepared for the sensing event, by which the βHBA concentration in the cow's blood and milk samples was determined via fluorescence analysis of the functionalized QDs. The detection was performed on a custom designed microfluidic platform combining with a low cost and miniaturized optical sensor. The sensing mechanism was first validated by a microplate reader method and then applied to the microfluidic platform. Standard βHBA solution, βHBA in blood and milk samples from cows were successfully measured by this novel technology with a detection limit at a level of 35 µM. Side by side comparison of the developed microfluidic biosensor with a commercial kit presented its good performance. PMID:25978442

  18. A Novel Cell-Based Hybrid Acoustic Wave Biosensor with Impedimetric Sensing Capabilities

    PubMed Central

    Liu, Fei; Li, Fang; Nordin, Anis Nurashikin; Voiculescu, Ioana

    2013-01-01

    A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs) were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device's sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35∼45 minutes for 1.5 × 104 cells/cm2 BAECs; 60 minutes for 2.0 × 104 cells/cm2 BAECs; 70 minutes for 3.0 × 104 cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection. PMID:23459387

  19. Adjustable bioadhesive control of PEGylated hyperbranch brushes on polystyrene microplate interface for the improved sensitivity of human blood typing.

    PubMed

    Chen, Yan-Wen; Chang, Yung; Lee, Rong-Ho; Li, Wen-Tyng; Chinnathambi, Arunachalam; Alharbi, Sulaiman Ali; Hsiue, Ging-Ho

    2014-08-01

    A PEGylated 96-well polystyrene (PS) microplate was first introduced for applications in high-throughput screening for selective blood typing to minimize the risks in blood transfusions. Herein, we present a hemocompatible PS 96-well microplate with adjustable PEGylated hyperbranch brush coverage prepared by ozone pretreated activation and thermally induced surface PEGylation. The grafting properties, hydration capacity, and blood compatibility of the PEGylated hyperbrush immobilized PS surfaces in human blood were illustrated by the combined chemical and physical properties of the surface, and the dependence of the specific absorption of human plasma fibrinogen onto the PEGylated surfaces on the grafting density was analyzed by monoclonal antibodies. The surface coverage of PEGylated brushes plays a major role in the bioadhesive properties of modified PS microplates, which in turn control the level of agglutination sensitivity in blood typing. The bioadhesive resistance toward proteins, platelets, and erythrocytes in human whole blood showed a correlation to the controlled hydration properties of the PEGylated hyperbrush-modified surfaces. Therefore, we suggested that the surface coverage of PEGylated hyperbrushes on PS surfaces can increase the sensitivity of cross-matching blood agglutination by up to 16-fold compared to that of the conventional 96-well virgin PS due to the regulated biorecognition of hematocrit and antibodies of the PEGylated hyperbrush-modified surfaces. PMID:25022949

  20. Effects of van der Waals Force and Thermal Stresses on Pull-in Instability of Clamped Rectangular Microplates

    PubMed Central

    Batra, Romesh C.; Porfiri, Maurizio; Spinello, Davide

    2008-01-01

    We study the influence of von Kármán nonlinearity, van der Waals force, and thermal stresses on pull-in instability and small vibrations of electrostatically actuated microplates. We use the Galerkin method to develop a tractable reduced-order model for electrostatically actuated clamped rectangular microplates in the presence of van der Waals forces and thermal stresses. More specifically, we reduce the governing two-dimensional nonlinear transient boundary-value problem to a single nonlinear ordinary differential equation. For the static problem, the pull-in voltage and the pull-in displacement are determined by solving a pair of nonlinear algebraic equations. The fundamental vibration frequency corresponding to a deflected configuration of the microplate is determined by solving a linear algebraic equation. The proposed reduced-order model allows for accurately estimating the combined effects of van der Waals force and thermal stresses on the pull-in voltage and the pull-in deflection profile with an extremely limited computational effort.

  1. Recent Advances in Nanotechnology Applied to Biosensors

    PubMed Central

    Zhang, Xueqing; Guo, Qin; Cui, Daxiang

    2009-01-01

    In recent years there has been great progress the application of nanomaterials in biosensors. The importance of these to the fundamental development of biosensors has been recognized. In particular, nanomaterials such as gold nanoparticles, carbon nanotubes, magnetic nanoparticles and quantum dots have been being actively investigated for their applications in biosensors, which have become a new interdisciplinary frontier between biological detection and material science. Here we review some of the main advances in this field over the past few years, explore the application prospects, and discuss the issues, approaches, and challenges, with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination. PMID:22399954

  2. PRINCIPLES OF AFFINITY-BASED BIOSENSORS

    EPA Science Inventory

    Despite the amount of resources that have been invested by national and international academic, government, and commercial sectors to develop affinity-based biosensor products, little obvious success has been realized through commercialization of these devices for specific applic...

  3. Non-antibody protein-based biosensors.

    PubMed

    Ko Ferrigno, Paul

    2016-06-30

    Biosensors that depend on a physical or chemical measurement can be adversely affected by non-specific interactions. For example, a biosensor designed to measure specifically the levels of a rare analyte can give false positive results if there is even a small amount of interaction with a highly abundant but irrelevant molecule. To overcome this limitation, the biosensor community has frequently turned to antibody molecules as recognition elements because they are renowned for their exquisite specificity. Unfortunately antibodies can often fail when immobilised on inorganic surfaces, and alternative biological recognition elements are needed. This article reviews the available non-antibody-binding proteins that have been successfully used in electrical and micro-mechanical biosensor platforms. PMID:27365032

  4. Non-antibody protein-based biosensors

    PubMed Central

    2016-01-01

    Biosensors that depend on a physical or chemical measurement can be adversely affected by non-specific interactions. For example, a biosensor designed to measure specifically the levels of a rare analyte can give false positive results if there is even a small amount of interaction with a highly abundant but irrelevant molecule. To overcome this limitation, the biosensor community has frequently turned to antibody molecules as recognition elements because they are renowned for their exquisite specificity. Unfortunately antibodies can often fail when immobilised on inorganic surfaces, and alternative biological recognition elements are needed. This article reviews the available non-antibody-binding proteins that have been successfully used in electrical and micro-mechanical biosensor platforms. PMID:27365032

  5. REVIEW ARTICLE: Environmental applications of analytical biosensors

    NASA Astrophysics Data System (ADS)

    Marco, María-Pilar; Barceló, Damià

    1996-11-01

    A review of the fundamental aspects and environmental applications of biosensors is presented. The bases of different transducer principles such as electrochemical, optical and piezoelectric are discussed. Various examples are given of the applications of such principles to develop immunosensor devices to determine common environmental contaminants. Attention is also paid to catalytic biosensors, using enzymes as sensing elements. Biosensor devices based on the use of cholinesterase and various oxidase enzymes such as tyrosinase, laccase, peroxidase and aldehyde dehydrogenase are reported. Some examples are given of the applications of other biomolecules such as whole cells, DNA or proteins, to determine pollution. Validation studies are presented comparing biosensors with chromatographic techniques to determine organophosphorus pesticides and phenolic compounds in environmental samples.

  6. Enzyme Nanoparticles-Based Electronic Biosensor

    SciTech Connect

    Liu, Guodong; Lin, Yuehe; Ostatna, V.; Wang, Joseph

    2005-06-28

    A novel method for fabricating electronic biosensors based on coupling enzyme nanoparticles and self assembly technology is illustrated. Redox horseradish peroxidase nanoparticles were prepared by desolvation with ethanol and subsequent crosslinking with glutaraldehyde. The cross-linked enzyme nanoparticles were functionalized by cysteine to introduce thiol groups on the nanoparticle surface. Immobilized enzyme nanoparticle on the gold electrode by self-assembly kept redox and electrocatalytic activities, and was used to develop reagentless biosensors for H2O2 detection without promoters and mediators. The new approach is simple, low cost and circumvents complications associated with solution systems. It is a universal immobilization method for biosensor, biomedical devices, biofuel cells and enzymatic bioreactors fabrication and expected to open new opportunities for biosensor, clinical diagnostics, and for bioanalysis, in general.

  7. Upgrading a microplate reader for photobiology and all-optical experiments.

    PubMed

    Richter, Florian; Scheib, Ulrike S; Mehlhorn, Jennifer; Schubert, Roman; Wietek, Jonas; Gernetzki, Oliver; Hegemann, Peter; Mathes, Tilo; Möglich, Andreas

    2015-02-01

    Automation can vastly reduce the cost of experimental labor and thus facilitate high experimental throughput, but little off-the-shelf hardware for the automation of illumination experiments is commercially available. Here, we use inexpensive open-source electronics to add programmable illumination capabilities to a multimode microplate reader. We deploy this setup to characterize light-triggered phenomena in three different sensory photoreceptors. First, we study the photoactivation of Arabidopsis thaliana phytochrome B by light of different wavelengths. Second, we investigate the dark-state recovery kinetics of the Synechocystis sp. blue-light sensor Slr1694 at multiple temperatures and imidazole concentrations; while the kinetics of the W91F mutant of Slr1694 are strongly accelerated by imidazole, the wild-type protein is hardly affected. Third, we determine the light response of the Beggiatoa sp. photoactivatable adenylate cyclase bPAC in Chinese hamster ovary cells. bPAC is activated by blue light in dose-dependent manner with a half-maximal intensity of 0.58 mW cm(-2); intracellular cAMP spikes generated upon bPAC activation decay with a half time of about 5 minutes after light switch-off. Taken together, we present a setup which is easily assembled and which thus offers a facile approach to conducting illumination experiments at high throughput, reproducibility and fidelity. PMID:25373866

  8. Cloning and expression profile of ionotropic receptors in the parasitoid wasp Microplitis mediator (Hymenoptera: Braconidae).

    PubMed

    Wang, Shan-Ning; Peng, Yong; Lu, Zi-Yun; Dhiloo, Khalid Hussain; Zheng, Yao; Shan, Shuang; Li, Rui-Jun; Zhang, Yong-Jun; Guo, Yu-Yuan

    2016-07-01

    Ionotropic receptors (IRs) mainly detect the acids and amines having great importance in many insect species, representing an ancient olfactory receptor family in insects. In the present work, we performed RNAseq of Microplitis mediator antennae and identified seventeen IRs. Full-length MmedIRs were cloned and sequenced. Phylogenetic analysis of the Hymenoptera IRs revealed that ten MmedIR genes encoded "antennal IRs" and seven encoded "divergent IRs". Among the IR25a orthologous groups, two genes, MmedIR25a.1 and MmedIR25a.2, were found in M. mediator. Gene structure analysis of MmedIR25a revealed a tandem duplication of IR25a in M. mediator. The tissue distribution and development specific expression of the MmedIR genes suggested that these genes showed a broad expression profile. Quantitative gene expression analysis showed that most of the genes are highly enriched in adult antennae, indicating the candidate chemosensory function of this family in parasitic wasps. Using immunocytochemistry, we confirmed that one co-receptor, MmedIR8a, was expressed in the olfactory sensory neurons. Our data will supply fundamental information for functional analysis of the IRs in parasitoid wasp chemoreception. PMID:27208597

  9. Nonlinear size-dependent dynamics of an imperfect shear deformable microplate

    NASA Astrophysics Data System (ADS)

    Farokhi, Hamed; Ghayesh, Mergen H.

    2016-01-01

    The nonlinear size-dependent dynamics of a geometrically imperfect shear deformable microplate is investigated based on the modified couple stress theory. An initial imperfection in the out-of-plane direction is taken into account. The third-order shear deformation theory is employed to model the system by retaining in-plane displacements and inertia. The governing equations of motion of the system are obtained employing an energy method through use of the Lagrange equations, which upon employing an assumed-mode technique, yields a set of second-order nonlinear ordinary differential equations with coupled terms. A high-dimensional discretised system is considered and made double-dimensional via a change of variables in order to obtain a set of first-order nonlinear ordinary differential equations. The resulting equations are solved using a direct time-integration technique, resulting in time-dependent generalised coordinates for the in-plane and out-of-plane displacements and two rotations. From these generalised coordinates, phase-plane portraits and fast Fourier transforms (FFTs) are also obtained. Moreover, the frequency-response and force-response curves of the system are obtained using a continuation technique; stability analysis is conducted via the Floquet theory. The effect of the initial imperfection as well as the length-scale parameter on the system response is also examined.

  10. Identification and Expression Analysis of Putative Chemosensory Receptor Genes in Microplitis mediator by Antennal Transcriptome Screening

    PubMed Central

    Wang, Shan-Ning; Peng, Yong; Lu, Zi-Yun; Dhiloo, Khalid Hussain; Gu, Shao-Hua; Li, Rui-Jun; Zhou, Jing-Jiang; Zhang, Yong-Jun; Guo, Yu-Yuan

    2015-01-01

    Host-seeking, ovipositional behavior and mating of insects are controlled mainly by odor perception through sensory organs such as antennae. Antennal chemoreception is extremely important for insect survival. Several antennal chemosensory receptors are involved in mediating the odor detection in insects, especially the odorant receptors (ORs) and ionotropic receptors (IRs), to ensure the specificity of the olfactory sensory neuron responses. In the present study, we identified the chemosensory receptor gene repertoire of the parasitoid wasp Microplitis mediator, a generalist endoparasitoid that infests more than 40 types of Lepidopterous larvae and is widely distributed in the Palaearctic region. By transcriptome sequencing of male and female antennae we identified 60 candidate odorant receptors, six candidate ionotropic receptors and two gustatory receptors in M. mediator. The full-length sequences of these putative chemosensory receptor genes were obtained by using the rapid amplification of cDNA ends PCR (RACE-PCR) method. We also conducted reverse transcription PCR (RT-PCR) combined with real-time quantitative PCR (qPCR) for investigating the expression profiles of these chemosensory receptor genes in olfactory and non-olfactory tissues. The tissue- and sex-biased expression patterns may provide insights into the roles of the chemosensory receptor in M. mediator. Our findings support possible future study of the chemosensory behavior of M. mediator at the molecular level. PMID:26078716

  11. Development of a fluorometric microplate antiadhesion assay using uropathogenic Escherichia coli and human uroepithelial cells.

    PubMed

    Kimble, Lindsey L; Mathison, Bridget D; Kaspar, Kerrie L; Khoo, Christina; Chew, Boon P

    2014-05-23

    A fluorometric microplate assay has been developed to determine Escherichia (E.) coli adhesion to uroepithelial cells (UEC). P-fimbriated E. coli were labeled with BacLight Green and preincubated 30 min with human urine or standard. Fluorescent-E. coli were added to UEC in mircoplates at a 400:1 ratio, incubated 1 h, and washed, and the fluorescence intensity was measured. Specific labeling and adherence were confirmed by flow cytometry. A myricetin (1) standard curve (0-30 μg/mL) was developed; the lower limit of detection was 0.1 μg/mL, and half-maximal inhibitory concentration was 0.88 μg/mL (intra- and interassay coefficients of variance were <10% and <15%, respectively). Vaccinium macrocarpon (cranberry) extracts, quercetin (2), and procyanidins B1 (3), B2 (4), and C1 (5) showed similar inhibition. Antiadhesion activity of urine samples from subjects (n = 12) consuming placebo or V. macrocarpon beverage determined using this assay was positively correlated (R(2) = 0.78; p < 0.01) with a radiolabeled-E. coli assay. PMID:24749980

  12. Analysis of Genetic Variation across the Encapsidated Genome of Microplitis demolitor Bracovirus in Parasitoid Wasps

    PubMed Central

    Burke, Gaelen R.

    2016-01-01

    Insect parasitoids must complete part of their life cycle within or on another insect, ultimately resulting in the death of the host insect. One group of parasitoid wasps, the ‘microgastroid complex’ (Hymenoptera: Braconidae), engage in an association with beneficial symbiotic viruses that are essential for successful parasitism of hosts. These viruses, known as Bracoviruses, persist in an integrated form in the wasp genome, and activate to replicate in wasp ovaries during development to ultimately be delivered into host insects during parasitism. The lethal nature of host-parasitoid interactions, combined with the involvement of viruses in mediating these interactions, has led to the hypothesis that Bracoviruses are engaged in an arms race with hosts, resulting in recurrent adaptation in viral (and host) genes. Deep sequencing was employed to characterize sequence variation across the encapsidated Bracovirus genome within laboratory and field populations of the parasitoid wasp species Microplitis demolitor. Contrary to expectations, there was a paucity of evidence for positive directional selection among virulence genes, which generally exhibited signatures of purifying selection. These data suggest that the dynamics of host-parasite interactions may not result in recurrent rounds of adaptation, and that adaptation may be more variable in time than previously expected. PMID:27390861

  13. Knockdown of microplitis mediator odorant receptor involved in the sensitive detection of two chemicals.

    PubMed

    Li, Ke-Ming; Ren, Li-Yan; Zhang, Yong-Jun; Wu, Kong-Ming; Guo, Yu-Yuan

    2012-03-01

    Odorant receptors are thought to play critical roles in the perception of chemosensory stimuli by insects. The primary method to address the functions of odorant receptors in insects is to use in vitro binding assays between the receptors and potential chemical stimuli. We injected MmedOrco dsRNA into the abdominal cavity of a braconid wasp, Microplitis mediator, and assayed for expression of this gene 72 h after treatment (RNAi). Quantitative real-time PCR demonstrated that the level of mRNA expression in MmedOrco dsRNA-treated M. mediator was significantly reduced (>90%) when compared with water-treated controls. Furthermore, electroantennogram (EAG) responses of M. mediator to two chemical attractants, nonanal and farnesene, were also reduced significantly (~70%) in RNAi-treated M. mediator when compared to controls. RNAi-treated M. mediator also responded by walking/flying at a lower rate to both chemicals when compared with controls in a Y-tube olfactometer bioassay, which provides direct evidence that MmedOrco plays an important role in perception of nonanal and farnesene in M. mediator. PMID:22402893

  14. Computational modeling and experimental validation of odor detection behaviors of classically conditioned parasitic wasp, Microplitis croceipes.

    PubMed

    Zhou, Zhongkun; Kulasiri, Don; Samarasinghe, Sandhya; Rains, Glen; Olson, Dawn M

    2015-01-01

    A prototype chemical sensor named Wasp hound® that utilizes five classically conditioned parasitoid wasps, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), to detect volatile odors was successfully implemented in a previous study. To improve the odor-detecting ability of Wasp Hound®, searching behaviors of an individual wasp in a confined area are studied and modeled through stochastic differential equations in this paper. The wasps are conditioned to 20 mg of coffee when associated with food and subsequently, tested to 5, 10, 20, and 40 mg of coffee. A stochastic model is developed and validated based on three positive behavioral responses (walking, rotation around odor source, and self-rotation) from conditioned wasps at four different test dosages. The model is capable to reproducing the behaviors of conditioned wasps, and can be used to improve the ability of Wasp Hound® to assess changes in odor concentration. The model simulation results show the behaviors of conditioned wasps are significantly different when tested at different coffee dosages. We conjecture that the searching behaviors of conditioned wasps are based on the temporal and spatial neuron activity of olfactory receptor neurons and glomeruli, which are strongly correlated to the training dosages. The overall results demonstrate the utility of mathematical models for interpreting experimental observations, gaining novel insights into the dynamic behavior of classically conditioned wasps, as well as broadening the practical uses of Wasp Hound. PMID:25482381

  15. Microplate biochemical determination of Russian VX: influence of admixtures and avoidance of false negative results.

    PubMed

    Prokofieva, Daria S; Jenkins, Richard O; Goncharov, Nikolay V

    2012-05-15

    Two microplate spectroscopic methods for determination of organophosphates, based on inhibition of acetylcholinesterase (AChE) activity, were further improved and evaluated for determination of the chemical weapon agent Russian VX (RVX) in aqueous solutions. The linear range of the Hestrin method (74.8-1120 pM) was 3.1-fold wider than that of the Ellman method (37.4-374 pM). Limits of detection and quantification of RVX for both methods were below the maximal allowable concentration of RVX in water-soluble washouts. One of the early products of RVX hydrolysis, N,N-diethylaminoethanethiol, like reduced glutathione, caused false negative results in the Ellman method at concentrations exceeding 10 μM; individual blanks were necessary to eliminate the effect. The Hestrin method showed greater specificity (~3 orders of magnitude) for analysis of samples containing mercaptans. A major product of RVX degradation, 2,2'-dithiobis(N,N-diethylethanamine), caused significant inhibition of AChE at concentrations of ≥0.1 mM (P<0.01) and had a false positive effect at higher concentrations (≥2 mM). For environmental monitoring of RVX, the method based on Hestrin is preferred over that based on Ellman, principally because the former method was less sensitive to interference from major admixtures and did not give rise to potentially dangerous false negative results. PMID:22381367

  16. High-throughput microplate assay for the determination of drug partition coefficients.

    PubMed

    Magalhães, Luís M; Nunes, Cláudia; Lúcio, Marlene; Segundo, Marcela A; Reis, Salette; Lima, José L F C

    2010-11-01

    Partition coefficients (K(p)) of drugs between the phospholipid bilayer and the aqueous phase provide useful information in quantitative structure-activity relationship studies. Hexadecylphosphocholine (HePC) micelles, composed of a zwitterionic hydrophilic surface and a hydrophobic core, mimic the biomembranes and have several advantages over other lipid structures to assess K(p) values. Their preparation is easy, fast and avoids the use of toxic organic solvents, and the output has fewer spectroscopic interferences. Here, we describe a high-throughput microplate protocol for assessing the K(p) of drugs using HePC micelles as membrane models and derivative spectrophotometry as the detection technique. Moreover, the time-consuming data treatment to assess K(p) values is easily performed by a dedicated Excel routine developed here and described in detail. The K(p) values of nonsteroidal anti-inflammatory drugs (acemetacin, clonixin, diclofenac and indomethacin) were determined to show the simplicity of the method and to validate this protocol, which provides K(p) values (n = 3) of two drugs in ∼ 2 h. PMID:21030957

  17. Rapid evaluation of oxygen and water permeation through microplate sealing tapes.

    PubMed

    Zimmermann, Hartmut F; John, Gernot T; Trauthwein, Harald; Dingerdissen, Uwe; Huthmacher, Klaus

    2003-01-01

    Eight commercially available microplate sealing tapes and 10 other suitable materials (transparent wound dressings) are compared qualitatively in terms of their ability to minimize water evaporation from a multiwell plate while maintaining the oxygen supply as high as possible, which is necessary for applications like aerobic growth. The transparency and sterility of the products are considered as well. All evaluated commercially available sealing tapes fall into one of the following two classes: (1) O(2) transfer is comparable to that of an unsealed plate, but water vapor retention is relatively low, or (2) O(2) transfer via the sealing is slower, but the water retention capability is comparably high. All but one of the evaluated wound dressings fall under the second class. That dressing, however, constitutes a compromise by showing both moderate O(2) permeability and medium water retention. But the estimated mass transport in a microtiter plate sealed with this dressing is about 5 times slower than that of an unsealed 96 well plate. The aim of this publication is to enable the reader to choose a microtiter plate sealing from the materials evaluated within this work and to use the rapid methods described herein to easily perform tests of additional sealing materials. PMID:12790681

  18. Rapid quantitative analysis of lipids using a colorimetric method in a microplate format.

    PubMed

    Cheng, Yu-Shen; Zheng, Yi; VanderGheynst, Jean S

    2011-01-01

    A colorimetric sulfo-phospho-vanillin (SPV) method was developed for high throughput analysis of total lipids. The developed method uses a reaction mixture that is maintained in a 96-well microplate throughout the entire assay. The new assay provides the following advantages over other methods of lipid measurement: (1) background absorbance can be easily corrected for each well, (2) there is less risk of handling and transferring sulfuric acid contained in reaction mixtures, (3) color develops more consistently providing more accurate measurement of absorbance, and (4) the assay can be used for quantitative measurement of lipids extracted from a wide variety of sources. Unlike other spectrophotometric approaches that use fluorescent dyes, the optimal spectra and reaction conditions for the developed assay do not vary with the sample source. The developed method was used to measure lipids in extracts from four strains of microalgae. No significant difference was found in lipid determination when lipid content was measured using the new method and compared to results obtained using a macro-gravimetric method. PMID:21069472

  19. Rapid microplate high-throughput methodology for assessment of Folin-Ciocalteu reducing capacity.

    PubMed

    Magalhães, Luís M; Santos, Fernando; Segundo, Marcela A; Reis, Salette; Lima, José L F C

    2010-12-15

    In the present work, a rapid and high-throughput Folin-Ciocalteu (F-C) reducing capacity assay adapted to routine/screening analysis was developed. In order to attain a fast F-C reducing kinetic reaction, the reaction conditions of the classical time-consuming F-C assay were modified and the influence of alkali and F-C reagent concentration was evaluated using gallic acid as standard. The proposed method was performed in a 96-well microplate format and it was applied to several phenolic compounds and food products (wines, beers, infusions and juices) providing F-C reducing capacity results after 3 min of reaction similar to those obtained by the time-consuming (120 min) conventional method. The additive and synergistic effect of reducing nonphenolic compounds usually found in food samples was also investigated. Ascorbic acid and ferrous sulfate provided an additive effect, while for fructose, glucose and sodium sulfite a synergistic effect was obtained. The detection limit was 0.25 mg L(-1) (as gallic acid) and the repeatability was <1.6% (n=12). PMID:21111158

  20. Analysis of Genetic Variation across the Encapsidated Genome of Microplitis demolitor Bracovirus in Parasitoid Wasps.

    PubMed

    Burke, Gaelen R

    2016-01-01

    Insect parasitoids must complete part of their life cycle within or on another insect, ultimately resulting in the death of the host insect. One group of parasitoid wasps, the 'microgastroid complex' (Hymenoptera: Braconidae), engage in an association with beneficial symbiotic viruses that are essential for successful parasitism of hosts. These viruses, known as Bracoviruses, persist in an integrated form in the wasp genome, and activate to replicate in wasp ovaries during development to ultimately be delivered into host insects during parasitism. The lethal nature of host-parasitoid interactions, combined with the involvement of viruses in mediating these interactions, has led to the hypothesis that Bracoviruses are engaged in an arms race with hosts, resulting in recurrent adaptation in viral (and host) genes. Deep sequencing was employed to characterize sequence variation across the encapsidated Bracovirus genome within laboratory and field populations of the parasitoid wasp species Microplitis demolitor. Contrary to expectations, there was a paucity of evidence for positive directional selection among virulence genes, which generally exhibited signatures of purifying selection. These data suggest that the dynamics of host-parasite interactions may not result in recurrent rounds of adaptation, and that adaptation may be more variable in time than previously expected. PMID:27390861

  1. Kinetic microplate bioassays for relative potency of antibiotics improved by partial Least Square (PLS) regression.

    PubMed

    Francisco, Fabiane Lacerda; Saviano, Alessandro Morais; Almeida, Túlia de Souza Botelho; Lourenço, Felipe Rebello

    2016-05-01

    Microbiological assays are widely used to estimate the relative potencies of antibiotics in order to guarantee the efficacy, safety, and quality of drug products. Despite of the advantages of turbidimetric bioassays when compared to other methods, it has limitations concerning the linearity and range of the dose-response curve determination. Here, we proposed to use partial least squares (PLS) regression to solve these limitations and to improve the prediction of relative potencies of antibiotics. Kinetic-reading microplate turbidimetric bioassays for apramacyin and vancomycin were performed using Escherichia coli (ATCC 8739) and Bacillus subtilis (ATCC 6633), respectively. Microbial growths were measured as absorbance up to 180 and 300min for apramycin and vancomycin turbidimetric bioassays, respectively. Conventional dose-response curves (absorbances or area under the microbial growth curve vs. log of antibiotic concentration) showed significant regression, however there were significant deviation of linearity. Thus, they could not be used for relative potency estimations. PLS regression allowed us to construct a predictive model for estimating the relative potencies of apramycin and vancomycin without over-fitting and it improved the linear range of turbidimetric bioassay. In addition, PLS regression provided predictions of relative potencies equivalent to those obtained from agar diffusion official methods. Therefore, we conclude that PLS regression may be used to estimate the relative potencies of antibiotics with significant advantages when compared to conventional dose-response curve determination. PMID:26971814

  2. Crocin bleaching antioxidant assay revisited: application to microplate to analyse antioxidant and pro-oxidant activities.

    PubMed

    Prieto, M A; Vázquez, J A; Murado, M A

    2015-01-15

    The crocin bleaching assay (CBA) is a common method for evaluating the antioxidant activity of hydrosoluble samples. It is criticised due to its low reproducibility, problematic quantification of results, differences in reagent preparation, doubtful need for a preheating phase and sensitivity to factors such as temperature, pH, solvents and metals. Here, the critical points of the method were extensively revised, and a highly reproducible procedure for microplate readers redeveloped. The problems of using quantification procedures, disregarding kinetic considerations, are discussed in detail and a model is proposed for quantifying simultaneously anti- and pro-oxidant activities as function of concentration and time. Thus, the combined use of a reproducible procedure and robust mathematical modeling produced consistent and meaningful criteria for comparative characterization of any oxidation modifier, taking into account the dose-time-dependent behaviour. The method was verified by characterising several commercial antioxidants and some metal compounds using the parametric values of the proposed models. The activity of the tested antioxidants decreased in the order ETX>TR>PG>AA>TBHQ>BHA. Others, such as the lipophilic antioxidants of BHT and α-Tocopherol did not show any activity. Interference from metals were for Fe(2+), Fe(3+), Cd(2+), Ni(2+), Mg(2+), Zn(2+) and Sr(2+), slightly antioxidant for Cu(1+) and Cu(2+), and strongly antioxidant for Mn(2+). None of the tested metals showed a pro-oxidant activity. PMID:25148992

  3. Electrochemical Biosensors - Sensor Principles and Architectures

    PubMed Central

    Grieshaber, Dorothee; MacKenzie, Robert; Vörös, Janos; Reimhult, Erik

    2008-01-01

    Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate

  4. Angle-resolved diffraction grating biosensor based on porous silicon

    NASA Astrophysics Data System (ADS)

    Lv, Changwu; Jia, Zhenhong; Liu, Yajun; Mo, Jiaqing; Li, Peng; Lv, Xiaoyi

    2016-03-01

    In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

  5. Biosensors for Inorganic and Organic Arsenicals

    PubMed Central

    Chen, Jian; Rosen, Barry P.

    2014-01-01

    Arsenic is a natural environmental contaminant to which humans are routinely exposed and is strongly associated with human health problems, including cancer, cardiovascular and neurological diseases. To date, a number of biosensors for the detection of arsenic involving the coupling of biological engineering and electrochemical techniques has been developed. The properties of whole-cell bacterial or cell-free biosensors are summarized in the present review with emphasis on their sensitivity and selectivity. Their limitations and future challenges are highlighted. PMID:25587436

  6. Gold coated ZnO nanorod biosensor for glucose detection

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Anuradha; Jain, Chhavi; Rao, V. Padmanapan; Banerjee, S.

    2012-06-01

    Gold coated ZnO nanorod based biosensor has been fabricated for its glucose detecting abilities and compared with that of ZnO nanorod based biosensor. SEM images of electrochemically grown ZnO nanorods show hexagonally grown ZnO nanorods on an ITO substrate. Electrochemical analysis show that gold coated ZnO based biosensors have higher sensitivity, lower limit of detection and a wider linear range for glucose detection. The results demonstrate that gold coated ZnO nanorod based biosensors are a promising material for biosensor applications over single component ZnO nanorod based biosensor.

  7. Integrated optical biosensor system (IOBS)

    DOEpatents

    Grace, Karen M.; Sweet, Martin R.; Goeller, Roy M.; Morrison, Leland Jean; Grace, Wynne Kevin; Kolar, Jerome D.

    2007-10-30

    An optical biosensor has a first enclosure with a pathogen recognition surface, including a planar optical waveguide and grating located in the first enclosure. An aperture is in the first enclosure for insertion of sample to be investigated to a position in close proximity to the pathogen recognition surface. A laser in the first enclosure includes means for aligning and means for modulating the laser, the laser having its light output directed toward said grating. Detection means are located in the first enclosure and in optical communication with the pathogen recognition surface for detecting pathogens after interrogation by the laser light and outputting the detection. Electronic means is located in the first enclosure and receives the detection for processing the detection and outputting information on the detection, and an electrical power supply is located in the first enclosure for supplying power to the laser, the detection means and the electronic means.

  8. Biosensors in clinical chemistry: An overview.

    PubMed

    Murugaiyan, Sathish Babu; Ramasamy, Ramesh; Gopal, Niranjan; Kuzhandaivelu, V

    2014-01-01

    Biosensors are small devices that employ biological/biochemical reactions for detecting target analytes. Basically, the device consists of a biocatalyst and a transducer. The biocatalyst may be a cell, tissue, enzyme or even an oligonucleotide. The transducers are mainly amperometric, potentiometric or optical. The classification of biosensors is based on (a) the nature of the recognition event or (b) the intimacy between the biocatalyst and the transducer. Bioaffinity and biocatalytic devices are examples for the former and the first, whereas second and third generation instruments are examples for the latter. Cell-based biosensors utilizing immobilized cells, tissues as also enzyme immunosensors and DNA biosensors find variegated uses in diagnostics. Enzyme nanoparticle-based biosensors make use of small particles in the nanometer scale and are currently making a mark in laboratory medicine. Nanotechnology can help in optimizing the diagnostic biochips, which would facilitate sensitive, rapid, accurate and precise bedside monitoring. Biosensors render themselves as capable diagnostic tools as they meet most of the above-mentioned criteria. PMID:24627875

  9. Integration of biosensors into digital microfluidics: Impact of hydrophilic surface of biosensors on droplet manipulation.

    PubMed

    Samiei, Ehsan; Luka, George S; Najjaran, Homayoun; Hoorfar, Mina

    2016-07-15

    Several studies have been performed on the integration of biosensors into digital microfluidics (DMF). Despite the general success in their detection capabilities, there are still two challenges associated with the integration of biosensors into DMF: (1) complete removal of the droplet containing the analytes from the sensing surface; and (2) biochemical regeneration of the biosensor involving detaching the target analyte from the receptor after each round of sensing. The latter is case dependent and the solution can vary from one application to another. Our research aims at addressing the former, the solution to which is applicable to all biosensors integrated to DMF. This paper presents a thorough characterization of the hydrophilic surface of the biosensor in terms of wettability and geometry, taking into account the overall configuration of the DMF platform. Consequently, we identify the optimal geometry of the sensing surface and the DMF platform providing successful removal of the target droplet from the sensing surface after detection. Based on the results, the gap height is suggested to be chosen at the upper limit of the applicable range. Also, the biosensor, patterned on the device top plate, is recommended to be designed with a high aspect ratio and aligned with the center of the actuating electrode. As a proof of concept, the optimum configuration is implemented on a DMF platform with an interdigitated capacitive biosensor to detect different concentrations of Cryptosporidium, for which it is shown that the sample droplet is removed successfully from the superhydrophilic surface of the biosensor. PMID:27016626

  10. Slotted photonic crystal sensors.

    PubMed

    Scullion, Mark G; Krauss, Thomas F; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  11. Slotted Photonic Crystal Sensors

    PubMed Central

    Scullion, Mark G.; Krauss, Thomas F.; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  12. A methodological combined framework for roadmapping biosensor research: a fault tree analysis approach within a strategic technology evaluation frame.

    PubMed

    Siontorou, Christina G; Batzias, Fragiskos A

    2014-03-01

    Biosensor technology began in the 1960s to revolutionize instrumentation and measurement. Despite the glucose sensor market success that revolutionized medical diagnostics, and artificial pancreas promise currently the approval stage, the industry is reluctant to capitalize on other relevant university-produced knowledge and innovation. On the other hand, the scientific literature is extensive and persisting, while the number of university-hosted biosensor groups is growing. Considering the limited marketability of biosensors compared to the available research output, the biosensor field has been used by the present authors as a suitable paradigm for developing a methodological combined framework for "roadmapping" university research output in this discipline. This framework adopts the basic principles of the Analytic Hierarchy Process (AHP), replacing the lower level of technology alternatives with internal barriers (drawbacks, limitations, disadvantages), modeled through fault tree analysis (FTA) relying on fuzzy reasoning to count for uncertainty. The proposed methodology is validated retrospectively using ion selective field effect transistor (ISFET) - based biosensors as a case example, and then implemented prospectively membrane biosensors, putting an emphasis on the manufacturability issues. The analysis performed the trajectory of membrane platforms differently than the available market roadmaps that, considering the vast industrial experience in tailoring and handling crystallic forms, suggest the technology path of biomimetic and synthetic materials. The results presented herein indicate that future trajectories lie along with nanotechnology, and especially nanofabrication and nano-bioinformatics, and focused, more on the science-path, that is, on controlling the natural process of self-assembly and the thermodynamics of bioelement-lipid interaction. This retained the nature-derived sensitivity of the biosensor platform, pointing out the differences

  13. SIRE-technology-based biosensors: will they do the job?

    NASA Astrophysics Data System (ADS)

    Kriz, Dario

    1997-06-01

    A new biosensor technology (SIRE--sensors based on injectable recognition elements) is described. Its application in laboratory equipment, medical survey equipment and process monitoring is reviewed. Furthermore, the promising practical and commercial relevance of SIRE- Biosensors is discussed.

  14. Optimization of Xenon Biosensors for Detection of ProteinInteractions

    SciTech Connect

    Lowery, Thomas J.; Garcia, Sandra; Chavez, Lana; Ruiz, E.Janette; Wu, Tom; Brotin, Thierry; Dutasta, Jean-Pierre; King, David S.; Schultz, Peter G.; Pines, Alex; Wemmer, David E..

    2005-08-03

    Hyperpolarized 129Xe NMR can detect the presence of specific low-concentration biomolecular analytes by means of the xenon biosensor, which consists of a water-soluble, targeted cryptophane-A cage that encapsulates xenon. In this work we use the prototypical biotinylated xenon biosensor to determine the relationship between the molecular composition of the xenon biosensor and the characteristics of protein-bound resonances. The effects of diastereomer overlap, dipole-dipole coupling, chemical shift anisotropy, xenon exchange, and biosensor conformational exchange on protein-bound biosensor signal were assessed. It was found that optimal protein-bound biosensor signal can be obtained by minimizing the number of biosensor diastereomers and using a flexible linker of appropriate length. Both the linewidth and sensitivity of chemical shift to protein binding of the xenon biosensor were found to be inversely proportional to linker length.

  15. Mohorovičić Discontinuity at the Contact of the Adriatic Microplate and Pannonian Segment

    NASA Astrophysics Data System (ADS)

    Sumanovac, F.; Oreskovic, J.

    2009-12-01

    Two-dimensional seismic and gravity modellings were applied to the contact of the Dinarides and the Pannonian basin as a relation between the Adriatic microplate and Pannonian segment, as a contribution to solving structural and tectonic relations. The basic exploration was carried out on the profile Alp07, which was a part of the ALP 2002 experiment (Brückl et al., 2003). This profile stretches in Croatia from Istra to the Drava River at Hungarian-Croatian border in a WSW-ENE direction. Two-dimensional seismic modelling was carried out using tomographic inversion and ray tracing technique. The Moho depth is the greatest in the area of the Dinarides, reaching about 40 km, and is shallowest (30 to 20 km) in the Pannonian basin. In order to obtain additional constraints on the crustal structure, 2 D gravity modelling was also performed. The layer boundaries were retained from the seismic model and varying of densities in the model produced a good fit to the data. A geological model was constructed based on both geophysical models (Šumanovac et al., 2009). Three types of the crust were found along the profile: the Dinaridic and the Pannonian crusts that are separated by a relatively wide Transition zone. The Dinaridic upper crust is characterised by low seismic velocities and densities, but its lower crust has high velocities and densities. The Pannonian crust can be seen as unique layer characterised by both low seismic velocities and densities. Large lateral and vertical changes in densities and seismic velocities can be found in the Transition zone. Gravity modelling on the Alp07 profile enabled a definition of calibrated rock densities that were applied on other profiles set up in the study area, generally covering the area of Croatia and Bosnia-Herzegovina, for the purpose of determining the structural relations. This significantly improved the resolution of gravity modelling, as well. The structural units determined on the Alp07 profile (Pannonian crust

  16. Break-up of Pangaea and Tectonic History of the Adria Microplate

    NASA Astrophysics Data System (ADS)

    Schettino, A.; Turco, E.

    2008-12-01

    A new kinematic model is proposed for the tectonic evolution of the western Tethys and the Adria microplate, constrained by the Atlantic plate kinematics and on land geologic evidences. The model defines thirteen tectonic phases, spanning the time interval from the late Ladinian (230 Ma) to the present. During the first phase, from the late Ladinian (230 Ma) to the latest Rhaetian (200 Ma), rifting proceeded along the eastern margin of North America, the northwest African margin, the High, Saharan and Tunisian Atlas, determining the formation of a separate Moroccan microplate at the interface between Gondwana and Laurasia. To the East, the break-up of Pangaea proceeded through a new phase of spreading in the central Mediterranean (Lagonegro basin) and the Tethys Ocean, while Adria remained attached to the southern Eurasian margin. During the second phase, from the latest Rhaetian (200 Ma) to the late Pliensbachian (185 Ma), oceanic crust started forming between the East Coast and Blake Spur magnetic anomalies, while the Morrocan Meseta simply continued to rift away from North America. During this time interval the Atlas rift reached its maximum extent. In the western Tethys region, cessation of spreading in the Lagonegro and Ionian Basins was accompanied by the formation of a new plate boundary which rifted Adria from Eurasia. The third phase, from the late Pliensbachian (185 Ma) to chron M21 (147.7 Ma), was triggered by the northward jump of the main plate boundary connecting the central Atlantic with the Tethys area. Therefore, as soon as rifting in the Atlas zone ceased, plate motion started along complex fault systems between Morocco and Iberia, while a rift/drift transition occurred in the northern segment of the central Atlantic, between Morocco and the conjugate margin of Nova Scotia. Sea floor spreading also started in the Mediterranean area, forming the Ligurian and Alpine Tethys oceans. The next two phases, from chron M21 (147.7 Ma) to chron M0 (120

  17. A single-islet microplate assay to measure mouse and human islet insulin secretion.

    PubMed

    Truchan, Nathan A; Brar, Harpreet K; Gallagher, Shannon J; Neuman, Joshua C; Kimple, Michelle E

    2015-01-01

    One complication to comparing β-cell function among islet preparations, whether from genetically identical or diverse animals or human organ donors, is the number of islets required per assay. Islet numbers can be limiting, meaning that fewer conditions can be tested; other islet measurements must be excluded; or islets must be pooled from multiple animals/donors for each experiment. Furthermore, pooling islets negates the possibility of performing single-islet comparisons. Our aim was to validate a 96-well plate-based single islet insulin secretion assay that would be as robust as previously published methods to quantify glucose-stimulated insulin secretion from mouse and human islets. First, we tested our new assay using mouse islets, showing robust stimulation of insulin secretion 24 or 48 h after islet isolation. Next, we utilized the assay to quantify mouse islet function on an individual islet basis, measurements that would not be possible with the standard pooled islet assay methods. Next, we validated our new assay using human islets obtained from the Integrated Islet Distribution Program (IIDP). Human islets are known to have widely varying insulin secretion capacity, and using our new assay we reveal biologically relevant factors that are significantly correlated with human islet function, whether displayed as maximal insulin secretion response or fold-stimulation of insulin secretion. Overall, our results suggest this new microplate assay will be a useful tool for many laboratories, expert or not in islet techniques, to be able to precisely quantify islet insulin secretion from their models of interest. PMID:26452321

  18. Electrophysiological and behavioral responses of Microplitis mediator (Hymenoptera: Braconidae) to caterpillar-induced volatiles from cotton.

    PubMed

    Yu, Huilin; Zhang, Yongjun; Wyckhuys, Kris A G; Wu, Kongming; Gao, Xiwu; Guo, Yuyuan

    2010-04-01

    Microplitis mediator Haliday (Hymenoptera: Braconidae) is an important larval endoparasitoid of various lepidopteran pests, including Helicoverpa armigera (Hübner). In China, H. armigera is a key pest of cotton and is currently the focus of several biological control efforts that use M. mediator as principal natural enemy of this pest. To improve the success of biological control efforts, behavioral studies are needed that shed light on the interaction between M. mediator and H. armigera. In this study, we determined M. mediator response to volatile compounds from undamaged, mechanically injured, or H. armigera--damaged plants and identified attractive volatiles. In Y-tube olfactometer assays, we found that mechanically damaged plants and/or plants treated with H. armigera oral secretions did not attract wasps. However, volatiles from H. armigera-damaged plants elicited a strong attraction of both M. mediator sexes. Headspace extracts from H. armigera-damaged cotton were analyzed by coupled gas chromatography-electroantennographic detection (GC-EAD), and a total of seven different compounds were found to elicit electroantennogram (EAG) responses, including an unknown compound. Six different EAD-active volatiles were identified from caterpillar-damaged cotton plants, of which 3, 7-dimethyl-1, 3, 6-octatriene and (Z)-3-hexenyl acetate were the principal compounds. Olfactometer assays indicated that individual synthetic compounds of 3, 7-dimethyl-1, 3, 6-octatriene, (Z)-3-hexenyl acetate, and nonanal were attractive to M. mediator. Field cage studies showed that parasitism of H. armigera larvae by M. mediator was higher on cotton plants to which 3,7-dimethyl-1,3, 6-octatriene was applied. Our results show that the combination of terpenoids and green leaf volatiles may not only facilitate host, mate, or food location but may also increase H. armigera parasitism by M. mediator. PMID:20388293

  19. Microplitis demolitor bracovirus genome segments vary in abundance and are individually packaged in virions

    SciTech Connect

    Beck, Markus H.; Inman, Ross B.; Strand, Michael R. . E-mail: mrstrand@bugs.ent.uga.edu

    2007-03-01

    Polydnaviruses (PDVs) are distinguished by their unique association with parasitoid wasps and their segmented, double-stranded (ds) DNA genomes that are non-equimolar in abundance. Relatively little is actually known, however, about genome packaging or segment abundance of these viruses. Here, we conducted electron microscopy (EM) and real-time polymerase chain reaction (PCR) studies to characterize packaging and segment abundance of Microplitis demolitor bracovirus (MdBV). Like other PDVs, MdBV replicates in the ovaries of females where virions accumulate to form a suspension called calyx fluid. Wasps then inject a quantity of calyx fluid when ovipositing into hosts. The MdBV genome consists of 15 segments that range from 3.6 (segment A) to 34.3 kb (segment O). EM analysis indicated that MdBV virions contain a single nucleocapsid that encapsidates one circular DNA of variable size. We developed a semi-quantitative real-time PCR assay using SYBR Green I. This assay indicated that five (J, O, H, N and B) segments of the MdBV genome accounted for more than 60% of the viral DNAs in calyx fluid. Estimates of relative segment abundance using our real-time PCR assay were also very similar to DNA size distributions determined from micrographs. Analysis of parasitized Pseudoplusia includens larvae indicated that copy number of MdBV segments C, B and J varied between hosts but their relative abundance within a host was virtually identical to their abundance in calyx fluid. Among-tissue assays indicated that each viral segment was most abundant in hemocytes and least abundant in salivary glands. However, the relative abundance of each segment to one another was similar in all tissues. We also found no clear relationship between MdBV segment and transcript abundance in hemocytes and fat body.

  20. Transdermal film-loaded finasteride microplates to enhance drug skin permeation: Two-step optimization study.

    PubMed

    Ahmed, Tarek A; El-Say, Khalid M

    2016-06-10

    The goal was to develop an optimized transdermal finasteride (FNS) film loaded with drug microplates (MIC), utilizing two-step optimization, to decrease the dosing schedule and inconsistency in gastrointestinal absorption. First; 3-level factorial design was implemented to prepare optimized FNS-MIC of minimum particle size. Second; Box-Behnken design matrix was used to develop optimized transdermal FNS-MIC film. Interaction among MIC components was studied using physicochemical characterization tools. Film components namely; hydroxypropyl methyl cellulose (X1), dimethyl sulfoxide (X2) and propylene glycol (X3) were optimized for their effects on the film thickness (Y1) and elongation percent (Y2), and for FNS steady state flux (Y3), permeability coefficient (Y4), and diffusion coefficient (Y5) following ex-vivo permeation through the rat skin. Morphological study of the optimized MIC and transdermal film was also investigated. Results revealed that stabilizer concentration and anti-solvent percent were significantly affecting MIC formulation. Optimized FNS-MIC of particle size 0.93μm was successfully prepared in which there was no interaction observed among their components. An enhancement in the aqueous solubility of FNS-MIC by more than 23% was achieved. All the studied variables, most of their interaction and quadratic effects were significantly affecting the studied variables (Y1-Y5). Morphological observation illustrated non-spherical, short rods, flakes like small plates that were homogeneously distributed in the optimized transdermal film. Ex-vivo study showed enhanced FNS permeation from film loaded MIC when compared to that contains pure drug. So, MIC is a successful technique to enhance aqueous solubility and skin permeation of poor water soluble drug especially when loaded into transdermal films. PMID:26993962

  1. Device considerations for development of conductance-based biosensors

    PubMed Central

    Lee, Kangho; Nair, Pradeep R.; Scott, Adina; Alam, Muhammad A.; Janes, David B.

    2009-01-01

    Design and fabrication of electronic biosensors based on field-effect-transistor (FET) devices require understanding of interactions between semiconductor surfaces and organic biomolecules. From this perspective, we review practical considerations for electronic biosensors with emphasis on molecular passivation effects on FET device characteristics upon immobilization of organic molecules and an electrostatic model for FET-based biosensors. PMID:24753627

  2. Nanomaterial-mediated Biosensors for Monitoring Glucose

    PubMed Central

    Taguchi, Masashige; Ptitsyn, Andre; McLamore, Eric S.

    2014-01-01

    Real-time monitoring of physiological glucose transport is crucial for gaining new understanding of diabetes. Many techniques and equipment currently exist for measuring glucose, but these techniques are limited by complexity of the measurement, requirement of bulky equipment, and low temporal/spatial resolution. The development of various types of biosensors (eg, electrochemical, optical sensors) for laboratory and/or clinical applications will provide new insights into the cause(s) and possible treatments of diabetes. State-of-the-art biosensors are improved by incorporating catalytic nanomaterials such as carbon nanotubes, graphene, electrospun nanofibers, and quantum dots. These nanomaterials greatly enhance biosensor performance, namely sensitivity, response time, and limit of detection. A wide range of new biosensors that incorporate nanomaterials such as lab-on-chip and nanosensor devices are currently being developed for in vivo and in vitro glucose sensing. These real-time monitoring tools represent a powerful diagnostic and monitoring tool for measuring glucose in diabetes research and point of care diagnostics. However, concerns over the possible toxicity of some nanomaterials limit the application of these devices for in vivo sensing. This review provides a general overview of the state of the art in nanomaterial-mediated biosensors for in vivo and in vitro glucose sensing, and discusses some of the challenges associated with nanomaterial toxicity. PMID:24876594

  3. A Microplate Growth Inhibition Assay for Screening Bacteriocins against Listeria monocytogenes to Differentiate Their Mode-of-Action

    PubMed Central

    Vijayakumar, Paul Priyesh; Muriana, Peter M.

    2015-01-01

    Lactic acid bacteria (LAB) have historically been used in food fermentations to preserve foods and are generally-recognized-as-safe (GRAS) by the FDA for use as food ingredients. In addition to lactic acid; some strains also produce bacteriocins that have been proposed for use as food preservatives. In this study we examined the inhibition of Listeria monocytogenes 39-2 by neutralized and non-neutralized bacteriocin preparations (Bac+ preps) produced by Lactobacillus curvatus FS47; Lb. curvatus Beef3; Pediococcus acidilactici Bac3; Lactococcus lactis FLS1; Enterococcus faecium FS56-1; and Enterococcus thailandicus FS92. Activity differences between non-neutralized and neutralized Bac+ preps in agar spot assays could not readily be attributed to acid because a bacteriocin-negative control strain was not inhibitory to Listeria in these assays. When neutralized and non-neutralized Bac+ preps were used in microplate growth inhibition assays against L. monocytogenes 39-2 we observed some differences attributed to acid inhibition. A microplate growth inhibition assay was used to compare inhibitory reactions of wild-type and bacteriocin-resistant variants of L. monocytogenes to differentiate bacteriocins with different modes-of-action (MOA) whereby curvaticins FS47 and Beef3, and pediocin Bac3 were categorized to be in MOA1; enterocins FS92 and FS56-1 in MOA2; and lacticin FLS1 in MOA3. The microplate bacteriocin MOA assay establishes a platform to evaluate the best combination of bacteriocin preparations for use in food applications as biopreservatives against L. monocytogenes. PMID:26111195

  4. Single-step method for β-galactosidase assays in Escherichia coli using a 96-well microplate reader.

    PubMed

    Schaefer, Jorrit; Jovanovic, Goran; Kotta-Loizou, Ioly; Buck, Martin

    2016-06-15

    Historically, the lacZ gene is one of the most universally used reporters of gene expression in molecular biology. Its activity can be quantified using an artificial substrate, o-nitrophenyl-ß-d-galactopyranoside (ONPG). However, the traditional method for measuring LacZ activity (first described by J. H. Miller in 1972) can be challenging for a large number of samples, is prone to variability, and involves hazardous compounds for lysis (e.g., chloroform, toluene). Here we describe a single-step assay using a 96-well microplate reader with a proven alternative cell permeabilization method. This modified protocol reduces handling time by 90%. PMID:27036618

  5. Microplate-based active/inactive 1° screen for biomass degrading enzyme library purification and gene discovery.

    PubMed

    Wagschal, Kurt; Lee, Charles C

    2012-04-01

    We present here a whole-cell and permeabilized E. coli cell 1° active/inactive microplate screen for β-d-xylosidase, xylanase, endoglucanase, and ferulic acid esterase enzyme activities, which are critical for the enzymatic deconstruction of biomass for fuels and chemicals. Transformants from genomic or mutagenesis-derived libraries are screened using fluorophore-tagged substrate/enzyme activity pairs that are assayed directly in the protein expression host growth media using a minimum of specialized equipment and supplies. PMID:22285853

  6. Single-step method for β-galactosidase assays in Escherichia coli using a 96-well microplate reader

    PubMed Central

    Schaefer, Jorrit; Jovanovic, Goran; Kotta-Loizou, Ioly; Buck, Martin

    2016-01-01

    Historically, the lacZ gene is one of the most universally used reporters of gene expression in molecular biology. Its activity can be quantified using an artificial substrate, o-nitrophenyl-ß-d-galactopyranoside (ONPG). However, the traditional method for measuring LacZ activity (first described by J. H. Miller in 1972) can be challenging for a large number of samples, is prone to variability, and involves hazardous compounds for lysis (e.g., chloroform, toluene). Here we describe a single-step assay using a 96-well microplate reader with a proven alternative cell permeabilization method. This modified protocol reduces handling time by 90%. PMID:27036618

  7. Field-Friendly Tuberculosis Biosensor

    NASA Astrophysics Data System (ADS)

    Proper, Nathan; Stone, Jeremy; Jevsevar, Kristen L.; Scherman, Michael; McNeil, Michael R.; Krapf, Diego

    2010-03-01

    Tuberculosis is a fading threat in the United States, but in the developing world it is still a major health-care concern. With the rising number of cases and lack of resources, there is a desperate need for an affordable, portable detection system. Here, we demonstrate the feasibility of a field-friendly immunological biosensor that utilizes florescence and specialized surface chemistries. We observe fluorescently labeled antibodies as they bind to a glass slide. Slides are treated with biotinylated polyethylene glycol to inhibit non-specific interactions and facilitate the binding of primary antibodies allowing for a high degree of specificity. Solutions of tuberculosis-specific antigens where mixed with fluorescently labeled secondary antibodies and incubated on the treated surfaces. An array of different concentrations of antigens bound to fluorescent tags is then read in an epifluorescnece microscope. This assay was used in the portable detector to show that higher concentrations of bound labeled antigens produce a greater emission when excited by a HeNe laser. Home-built electronics, off-the-shelf optics, and a Si photodiode (PD) were used. The data collected from multiple concentrations show a measurable photocurrent. Work is now underway to incorporate a avalanche (PD), flow-cell technology, in a portable box.

  8. MRI Biosensors: A Short Primer

    PubMed Central

    Louie, Angelique

    2013-01-01

    Interest in Magnetic Resonance Imaging (MRI) contrast agents for molecular imaging of biological function experienced a surge of excitement approximately 20 years ago with the development of the first activatable contrast agents that could act as biosensors and turn “on” in response to a specific biological activity. This brief tutorial, based on a short course lecture from the 2011 ISMRM meeting, provides an overview of underlying principles governing the design of biosensing contrast agents. We describe mechanisms by which a magnetic resonance imaging (MRI) contrast agent can be made into a sensor for both T1 and T2 types contrast agents. Examples of biological activities that can interact with a contrast agent are discussed using specific examples from the recent literature to illustrate the primary mechanisms of action that have been utilized to achieve activation. MRI sensors for pH, ion binding, enzyme cleavage, and oxidation-reduction are presented. This article is not meant to be an exhaustive review, but an illustrative primer to explain how activation can be achieved for an MRI contrast agent. Chemical exchange saturation transfer (CEST) is not covered as these agents were covered in a separate lecture. PMID:23996662

  9. A recyclable chitosan-based QCM biosensor for sensitive and selective detection of breast cancer cells in real time.

    PubMed

    Zhang, Shaolian; Bai, Haihua; Luo, Jinmei; Yang, Peihui; Cai, Jiye

    2014-12-01

    A highly sensitive and recyclable quartz crystal microbalance (QCM) biosensor was developed using chitosan (CS) and folic acid (FA), generating conjugates that are selectively recognized by MCF-7 cancer cell over-expressed folic acid receptors. The prepared CS-FA conjugate was characterized by UV-vis spectroscopy and Fourier transform infrared spectroscopy. Atomic force microscopy and scanning electron microscopy further presented the morphology of the CS-FA conjugate interface. The hydrophilicity of films was characterized by measuring the contact angle. The recognition of MCF-7 cancer cells was investigated in situ using QCM. Captured by FA, the concentration of the MCF-7 cell was determined on-line using a quartz crystal microbalance and a wide linear range of 4.5 × 10(2) to 1.01 × 10(5) cells per mL was obtained, with a detection limit of 430 cells per mL. The fluorescence microscope further confirmed the specificity and biocompatibility of the constructed biosensor. In addition, the regeneration of the QCM biosensor was studied by using lysozyme. This receptor-bound ligand based QCM biosensor also showed good selectivity, and repeatability in the cell mixture. For the first time, this simple, economical and label-free chitosan-based QCM sensing was demonstrated, and such design could provide a promising detection strategy for sensitive detection of cancer cell over-expressed folic acid receptors. PMID:25313373

  10. Ultra-sensitive immunoassay biosensors using hybrid plasmonic-biosilica nanostructured materials.

    PubMed

    Yang, Jing; Zhen, Le; Ren, Fanghui; Campbell, Jeremy; Rorrer, Gregory L; Wang, Alan X

    2015-08-01

    We experimentally demonstrate an ultra-sensitive immunoassay biosensor using diatom biosilica with self-assembled plasmonic nanoparticles. As the nature-created photonic crystal structures, diatoms have been adopted to enhance surface plasmon resonances of metal nanoparticles on the surfaces of diatom frustules and to increase the sensitivity of surface-enhanced Raman scattering (SERS). In this study, a sandwich SERS immunoassay is developed based on the hybrid plasmonic-biosilica nanostructured materials that are functionalized with goat anti-mouse IgG. Our experimental results show that diatom frustules improve the detection limit of mouse IgG to 10 pg/mL, which is ˜100× better than conventional colloidal SERS sensors on flat glass. Ultra-sensitive immunoassay biosensor using diatom biosilica with self-assembled plasmonic nanoparticles. PMID:25256544

  11. Hydrotalcite-like anionic clays substituted with iron / laccase, composites for biosensors applications

    NASA Astrophysics Data System (ADS)

    Carja, Gabriela; Ciobanu, Gabriela; Apostolescu, Gabriela; Dranca, Sofronia; Apostolescu, Nicolae

    2009-01-01

    Laccase - based biosensors are important for the selective determination of the phenolic compounds in the environmental matrices. The features of the enzyme immobilisation process and the characteristics of the inorganic porous matrix adsorbed on the electrode surface are both important for establishing the biosensor performances. This work presents the synthesis and physical-chemical characteristics of new hybrid materials based on iron containing layered double hydroxides / laccase. XRD and TGA-DTA analyses give information about the structural characteristics and thermal behaviour of the tested hybrids. The SEM images show the presence of a well crystallized texture of organized ensembles of platelets-like particles stacking on top of one another. The presence of iron in the substituted clay matrix is able to give rise to the specific redox properties that can be further used to tailor not only the laccase immobilisation process but also the biological sensing response of the biohybrid-transducer device.

  12. HNO₃-assisted polyol synthesis of ultralarge single-crystalline Ag microplates and their far propagation length of surface plasmon polariton.

    PubMed

    Chang, Cheng-Wei; Lin, Fan-Cheng; Chiu, Chun-Ya; Su, Chung-Yi; Huang, Jer-Shing; Perng, Tsong-Pyng; Yen, Ta-Jen

    2014-07-23

    We developed a HNO3-assisted polyol reduction method to synthesize ultralarge single-crystalline Ag microplates routinely. The edge length of the synthesized Ag microplates reaches 50 μm, and their top facets are (111). The mechanism for dramatically enlarging single-crystalline Ag structure stems from a series of competitive anisotropic growths, primarily governed by carefully tuning the adsorption of Ag(0) by ethylene glycol and the desorption of Ag(0) by a cyanide ion on Ag(100). Finally, we measured the propagation length of surface plasmon polaritons along the air/Ag interface under 534 nm laser excitation. Our single-crystalline Ag microplate exhibited a propagation length (11.22 μm) considerably greater than that of the conventional E-gun deposited Ag thin film (5.27 μm). PMID:24987801

  13. Thin Hydrogel Films for Optical Biosensor Applications

    PubMed Central

    Mateescu, Anca; Wang, Yi; Dostalek, Jakub; Jonas, Ulrich

    2012-01-01

    Hydrogel materials consisting of water-swollen polymer networks exhibit a large number of specific properties highly attractive for a variety of optical biosensor applications. This properties profile embraces the aqueous swelling medium as the basis of biocompatibility, non-fouling behavior, and being not cell toxic, while providing high optical quality and transparency. The present review focuses on some of the most interesting aspects of surface-attached hydrogel films as active binding matrices in optical biosensors based on surface plasmon resonance and optical waveguide mode spectroscopy. In particular, the chemical nature, specific properties, and applications of such hydrogel surface architectures for highly sensitive affinity biosensors based on evanescent wave optics are discussed. The specific class of responsive hydrogel systems, which can change their physical state in response to externally applied stimuli, have found large interest as sophisticated materials that provide a complex behavior to hydrogel-based sensing devices. PMID:24957962

  14. Graphene-Based Optical Biosensors and Imaging

    SciTech Connect

    Tang, Zhiwen; He, Shijiang; Pei, Hao; Du, Dan; Fan, Chunhai; Lin, Yuehe

    2014-01-13

    This chapter focuses on the design, fabrication and application of graphene based optical nanobiosensors. The emerging graphene based optical nanobiosensors demonstrated the promising bioassay and biomedical applications thanking to the unique optical features of graphene. According to the different applications, the graphene can be tailored to form either fluorescent emitter or efficient fluorescence quencher. The exceptional electronic feature of graphene makes it a powerful platform for fabricating the SPR and SERS biosensors. Today the graphene based optical biosensors have been constructed to detect various targets including ions, small biomolecules, DNA/RNA and proteins. This chapter reviews the recent progress in graphene-based optical biosensors and discusses the opportunities and challenges in this field.

  15. Antibodies and antibody-derived analytical biosensors.

    PubMed

    Sharma, Shikha; Byrne, Hannah; O'Kennedy, Richard J

    2016-06-30

    The rapid diagnosis of many diseases and timely initiation of appropriate treatment are critical determinants that promote optimal clinical outcomes and general public health. Biosensors are now being applied for rapid diagnostics due to their capacity for point-of-care use with minimum need for operator input. Antibody-based biosensors or immunosensors have revolutionized diagnostics for the detection of a plethora of analytes such as disease markers, food and environmental contaminants, biological warfare agents and illicit drugs. Antibodies are ideal biorecognition elements that provide sensors with high specificity and sensitivity. This review describes monoclonal and recombinant antibodies and different immobilization approaches crucial for antibody utilization in biosensors. Examples of applications of a variety of antibody-based sensor formats are also described. PMID:27365031

  16. Hydrogen peroxide biosensor based on titanium oxide

    NASA Astrophysics Data System (ADS)

    Halim, Nur Hamidah Abdul; Heng, Lee Yook; Hashim, Uda

    2015-09-01

    In this work, a biosensor utilizing modified titania, TiO2 particles using aminopropyl-triethoxy-silane, (APTS) for developing hydrogen peroxide biosensor is presented. The surface of Ti-APTS particles is used as a support for hemoglobin immobilization via covalent bonding. The performance of the biosensor is determined by differential pulse voltammetry. The linear response was observed at the reduction current of redox mediator probe [FeCN6]3-/4- at potential between 0.22 V to 0.24 V. The preliminary result for electrochemistry study on this modified electrode is reported. The preliminary linear range is obtained from 1×10-2 M to 1×10-8 M.

  17. Antibodies and antibody-derived analytical biosensors

    PubMed Central

    Sharma, Shikha; Byrne, Hannah

    2016-01-01

    The rapid diagnosis of many diseases and timely initiation of appropriate treatment are critical determinants that promote optimal clinical outcomes and general public health. Biosensors are now being applied for rapid diagnostics due to their capacity for point-of-care use with minimum need for operator input. Antibody-based biosensors or immunosensors have revolutionized diagnostics for the detection of a plethora of analytes such as disease markers, food and environmental contaminants, biological warfare agents and illicit drugs. Antibodies are ideal biorecognition elements that provide sensors with high specificity and sensitivity. This review describes monoclonal and recombinant antibodies and different immobilization approaches crucial for antibody utilization in biosensors. Examples of applications of a variety of antibody-based sensor formats are also described. PMID:27365031

  18. Development of a biosensor for caffeine.

    PubMed

    Babu, V R Sarath; Patra, S; Karanth, N G; Kumar, M A; Thakur, M S

    2007-01-23

    We have utilized a microbe, which can degrade caffeine to develop an Amperometric biosensor for determination of caffeine in solutions. Whole cells of Pseudomonas alcaligenes MTCC 5264 having the capability to degrade caffeine were immobilized on a cellophane membrane with a molecular weight cut off (MWCO) of 3000-6000 by covalent crosslinking method using glutaraledhyde as the bifunctional crosslinking agent and gelatin as the protein based stabilizing agent (PBSA). The biosensor system was able to detect caffeine in solution over a concentration range of 0.1 to 1 mg mL(-1). With read-times as short as 3 min, this caffeine biosensor acts as a rapid analysis system for caffeine in solutions. Interestingly, successful isolation and immobilization of caffeine degrading bacteria for the analysis of caffeine described here was enabled by a novel selection strategy that incorporated isolation of caffeine degrading bacteria capable of utilizing caffeine as the sole source of carbon and nitrogen from soils and induction of caffeine degrading capacity in bacteria for the development of the biosensor. This biosensor is highly specific for caffeine and response to interfering compounds such as theophylline, theobromine, paraxanthine, other methyl xanthines and sugars was found to be negligible. Although a few biosensing methods for caffeine are reported, they have limitations in application for commercial samples. The development and application of new caffeine detection methods remains an active area of investigation, particularly in food and clinical chemistry. The optimum pH and temperature of measurement were 6.8 and 30+/-2 degrees C, respectively. Interference in analysis of caffeine due to different substrates was observed but was not considerable. Caffeine content of commercial samples of instant tea and coffee was analyzed by the biosensor and the results compared well with HPLC analysis. PMID:17386510

  19. Biosensor technology for pesticides--a review.

    PubMed

    Verma, Neelam; Bhardwaj, Atul

    2015-03-01

    Pesticides, due to their lucrative outcomes, are majorly implicated in agricultural fields for crop production enhancement. Due to their pest removal properties, pesticides of various classes have been designed to persist in the environment over a longer duration after their application to achieve maximum effectiveness. Apart from their recalcitrant structure and agricultural benefits, pesticides also impose acute toxicological effects onto the other various life forms. Their accumulation in the living system may prove to be detrimental if established in higher concentrations. Thus, their prompt and accurate analysis is a crucial matter of concern. Conventional techniques like chromatographic techniques (HPLC, GC, etc.) used for pesticides detection are associated with various limitations like stumpy sensitivity and efficiency, time consumption, laboriousity, requirement of expensive equipments and highly trained technicians, and many more. So there is a need to recruit the methods which can detect these neurotoxic compounds sensitively, selectively, rapidly, and easily in the field. Present work is a brief review of the pesticide effects, their current usage scenario, permissible limits in various food stuffs and 21st century advancements of biosensor technology for pesticide detection. Due to their exceptional performance capabilities, easiness in operation and on-site working, numerous biosensors have been developed for bio-monitoring of various environmental samples for pesticide evaluation immensely throughout the globe. Till date, based on sensing element (enzyme based, antibody based, etc.) and type of detection method used (Electrochemical, optical, and piezoelectric, etc.), a number of biosensors have been developed for pesticide detection. In present communication, authors have summarized 21st century's approaches of biosensor technology for pesticide detection such as enzyme-based biosensors, immunosensors, aptamers, molecularly imprinted polymers, and

  20. Assembling Amperometric Biosensors for Clinical Diagnostics

    PubMed Central

    Belluzo, María Soledad; Ribone, María Élida; Lagier, Claudia Marina

    2008-01-01

    Clinical diagnosis and disease prevention routinely require the assessment of species determined by chemical analysis. Biosensor technology offers several benefits over conventional diagnostic analysis. They include simplicity of use, specificity for the target analyte, speed to arise to a result, capability for continuous monitoring and multiplexing, together with the potentiality of coupling to low-cost, portable instrumentation. This work focuses on the basic lines of decisions when designing electron-transfer-based biosensors for clinical analysis, with emphasis on the strategies currently used to improve the device performance, the present status of amperometric electrodes for biomedicine, and the trends and challenges envisaged for the near future.

  1. Fluorescent labels in biosensors for pathogen detection.

    PubMed

    Li, Bianmiao; Yu, Qiaoling; Duan, Yixiang

    2015-03-01

    Infectious diseases caused by pathogens have become a life-threatening problem for millions of people around the world in recent years. Therefore, the need of efficient, fast, low-cost and user-friendly biosensing systems to monitor pathogen has increased enormously in the last few years. This paper presents an overview of different fluorescent labels and the utilization of fluorescence-based biosensor techniques for rapid, direct, sensitive and real-time identification of bacteria. In these biosensors, organic dyes, nanomaterials and rare-earth elements are playing an increasing role in the design of biosensing systems with an interest for applications in bacterial analysis. PMID:23886349

  2. Design and application of genetically encoded biosensors

    PubMed Central

    Palmer, Amy E.; Qin, Yan; Park, Jungwon Genevieve; McCombs, Janet E.

    2012-01-01

    In the past 5–10 years, the power of the green fluorescent protein (GFP) and its numerous derivatives has been harnessed toward the development of genetically encoded fluorescent biosensors. These sensors are incorporated into cells or organisms as plasmid DNA, which leads the transcriptional and translational machinery of the cell to express a functional sensor. To date, over 100 different genetically encoded biosensors have been developed for targets as diverse as ions, molecules and enzymes. Such sensors are instrumental in providing a window into the real-time biochemistry of living cells and whole organisms, and are providing unprecedented insight into the inner workings of a cell. PMID:21251723

  3. Mathematical Model of the Biosensors Acting in a Trigger Mode

    PubMed Central

    Baronas, Romas; Kulys, Juozas; Ivanauskas, Feliksas

    2004-01-01

    A mathematical model of biosensors acting in a trigger mode has been developed. One type of the biosensors utilized a trigger enzymatic reaction followed by the cyclic enzymatic and electrochemical conversion of the product (CCE scheme). Other biosensors used the enzymatic trigger reaction followed by the electrochemical and enzymatic product cyclic conversion (CEC scheme). The models were based on diffusion equations containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reactions. The digital simulation was carried out using the finite difference technique. The influence of the substrate concentration, the maximal enzymatic rate as well as the membrane thickness on the biosensor response was investigated. The numerical experiments demonstrated a significant gain (up to dozens of times) in biosensor sensitivity when the biosensor response was under diffusion control. In the case of significant signal amplification, the response time with triggering was up to several times longer than that of the biosensor without triggering.

  4. Analysis of thermoelastic dissipation in circular micro-plate resonators using the generalized thermoelasticity theory of dual-phase-lagging model

    NASA Astrophysics Data System (ADS)

    Guo, F. L.; Song, J.; Wang, G. Q.; Zhou, Y. F.

    2014-05-01

    This study investigates the thermoelastic dissipation of micro-plate resonators by using the generalized thermoelasticity theory of dual-phase-lagging model. Explicit formulae of thermoelastic damping and frequency shift are derived. Influences of the plate thickness and vibration frequency on the thermoelastic damping are examined. Phenomena distinct from those of classical theory are observed in the numerical results of thermoelastic damping in micro-plate resonators. These results may bring new insights into the study of thermoelastic damping at submicrometer or nanometer scale.

  5. A Colorimetric Microplate Assay for DNA-Binding Activity of His-Tagged MutS Protein.

    PubMed

    Banasik, Michał; Sachadyn, Paweł

    2016-09-01

    A simple microplate method was designed for rapid testing DNA-binding activity of proteins. The principle of the assay involves binding of tested DNA by his-tagged protein immobilized on a nickel-coated ELISA plate, following colorimetric detection of biotinylated DNA with avidin conjugated to horseradish peroxidase. The method was used to compare DNA mismatch binding activities of MutS proteins from three bacterial species. The assay required relatively low amounts of tested protein (approximately 0.5-10 pmol) and DNA (0.1-10 pmol) and a relatively short time of analysis (up to 60 min). The method is very simple to apply and convenient to test different buffer conditions of DNA-protein binding. Sensitive colorimetric detection enables naked eye observations and quantitation with an ELISA reader. The performance of the assay, which we believe is a distinguishing trait of the method, is based on two strong and specific molecular interactions: binding of a his-tagged protein to a nickel-coated microplate and binding of biotinylated DNA to avidin. In the reported experiments, the solution was used to optimize the conditions for DNA mismatch binding by MutS protein; however, the approach could be implemented to test nucleic acids interactions with any protein of interest. PMID:27241123

  6. An optimized microplate assay system for quantitative evaluation of plant cell wall-degrading enzyme activity of fungal culture extracts.

    PubMed

    King, Brian C; Donnelly, Marie K; Bergstrom, Gary C; Walker, Larry P; Gibson, Donna M

    2009-03-01

    Developing enzyme cocktails for cellulosic biomass hydrolysis complementary to current cellulase systems is a critical step needed for economically viable biofuels production. Recent genomic analysis indicates that some plant pathogenic fungi are likely a largely untapped resource in which to prospect for novel hydrolytic enzymes for biomass conversion. In order to develop high throughput screening assays for enzyme bioprospecting, a standardized microplate assay was developed for rapid analysis of polysaccharide hydrolysis by fungal extracts, incorporating biomass substrates. Fungi were grown for 10 days on cellulose- or switchgrass-containing media to produce enzyme extracts for analysis. Reducing sugar released from filter paper, Avicel, corn stalk, switchgrass, carboxymethylcellulose, and arabinoxylan was quantified using a miniaturized colorimetric assay based on 3,5-dinitrosalicylic acid. Significant interactions were identified among fungal species, growth media composition, assay substrate, and temperature. Within a small sampling of plant pathogenic fungi, some extracts had crude activities comparable to or greater than T. reesei, particularly when assayed at lower temperatures and on biomass substrates. This microplate assay system should prove useful for high-throughput bioprospecting for new sources of novel enzymes for biofuel production. PMID:18973283

  7. Space-time model for migration of weak earthquakes along the northern boundary of the Amurian microplate

    NASA Astrophysics Data System (ADS)

    Trofimenko, S. V.; Bykov, V. G.; Merkulova, T. V.

    2016-07-01

    In this paper, we aimed to investigate the statistical distributions of shallow earthquakes with 2 ≤ M ≤ 4, located in 13 rectangular areas (clusters) bounded by 120°E and 144°E along the northern boundary of the Amurian microplate. As a result of our study, the displacement of seismicity maxima has been determined and three recurrent spatial cycles have been observed. The clusters with similar distribution of earthquakes are suggested to alternate being equally spaced at 7.26° (360-420 km). A comparison of investigation results on the structure of seismicity in various segments of the Amurian microplate reveals the identity between the alternation pattern observed for meridional zones of large earthquakes and a distinguished spatial period. The displacement vector for seismicity in the annual cycles is determined, and the correspondence between its E-W direction and the displacement of the fronts of large earthquakes is established. The elaborated model of seismic and deformation processes is considered, in which subsequent activation of clusters of weak earthquakes (2 ≤ M ≤ 4), tending to extend from the Japanese-Sakhalin island arc to the eastern closure of the Baikal rift zone, is initiated by the displacement of the strain wave front.

  8. A comparison of fluorescamine and naphthalene-2,3-dicarboxaldehyde fluorogenic reagents for microplate-based detection of amino acids.

    PubMed

    Bantan-Polak, T; Kassai, M; Grant, K B

    2001-10-15

    The use of appropriate fluorometric derivatization procedures is of considerable importance for accurate determination of amino acids in biological samples and in metal-assisted peptide hydrolysis reactions. It is especially critical for the relative fluorescence intensities (RFI) of equal amounts of amino acids to be as similar as possible. While fluorescamine and naphthalene-2,3-dicarboxaldehyde (NDA) have proven to be excellent fluorogenic reagents for amino acid detection, the effects of various factors such as organic solvent, buffer, and pH have never been rigorously evaluated with respect to normalizing the relative fluorescence intensities of individual amino acids. To this end, here we describe optimized fluorescamine and NDA derivatization reactions that enhance the accuracy of microplate-based detection of amino acids. For both fluorescamine and NDA, we have shown that the RFI values of 16 of 19 amino acids are greater than 70%. Although determination of tryptophan is problematic, this difficulty is overcome by the addition of beta-cyclodextrin to the NDA reaction. In principle, the optimized fluorescamine and NDA microplate procedures reported here can be utilized as complementary techniques for the detection of 19 of 20 naturally occurring amino acids. PMID:11673879

  9. Long-term storage of compound solutions for high-throughput screening by using a novel 1536-well microplate.

    PubMed

    Pfeifer, Martin Joseph; Scheel, Guenther

    2009-06-01

    This report describes the features and the performance of a new and significantly improved 1536-well microplate design. The design allows for simple, automation-friendly, and cost-effective storage of compound solutions for high-throughput screening. The plate design is based on Society for Biomolecular Sciences standards for microplates and can be molded from polystyrene or cycloolefin copolymer, thus making the plate suitable for use with acoustic dispensing as well as other conventional liquid dispensing in the nanoliter range. For a 9:1 DMSO/water mix as solvent, the novel plate design has shown to perform over 4 months with only minor losses in solvent. Thus, this novel plate design creates the basis for further reductions in compound storage volumes and allows for an increase in the storage times for microliter volumes for up to a year or more. The high protection against solvent evaporation is also visible for aqueous solutions, thus allowing for reduced edge effects during screening campaigns. PMID:19487771

  10. Biosensor Systems for Homeland Security

    SciTech Connect

    Bruckner-Lea, Cindy J.

    2004-05-30

    The detection of biological agents is important to minimize the effects of pathogens that can harm people, livestock, or plants. In addition to pathogens distributed by man, there is a need to detect natural outbreaks. Recent outbreaks of SARS, mad cow disease, pathogenic E. coli and Salmonella, as well as the discovery of letters filled with anthrax spores have highlighted the need for biosensor systems to aid in prevention, early warning, response, and recovery. Rapid detection can be used to prevent exposure; and detection on a longer timescale can be used to minimize exposure, define treatment, and determine whether contaminated areas are clean enough for reuse. The common types of biological agents of concern include bacteria, spores, and viruses (Figure 1). From a chemist’s point of view, pathogens are essentially complex packages of chemicals that are assembled into organized packages with somewhat predictable physical characteristics such as size and shape. Pathogen detection methods can be divided into three general approaches: selective detection methods for specific identification such as nucleic acid analysis and structural recognition, semi-selective methods for broad-spectrum detection (e.g. physical properties, metabolites, lipids), and function-based methods (e.g. effect of the pathogen on organisms, tissues, or cells). The requirements for biodetection systems depend upon the application. While detect to warn sensors may require rapid detection on the order one minute, detection times of many minutes or hours may be suitable for determining appropriate treatments or for forensic analysis. Of course ideal sensor systems will meet the needs of many applications, and will be sensitive, selective, rapid, and simultaneously detect all agents of concern. They will also be reliable with essentially no false negatives or false positives, small, easy to use, and low cost with minimal consumables.

  11. A disposable, reagentless, third-generation glucose biosensor based on overoxidized poly(pyrrole)/tetrathiafulvalene-tetracyanoquinodimethane composite.

    PubMed

    Palmisano, Francesco; Zambonin, Pier Giorgio; Centonze, Diego; Quinto, Maurizio

    2002-12-01

    A disposable glucose biosensor based on glucose oxidase immobilized on tetrathiafulvalene-tetracyanoquinodimethane (ITF-TCNQ) conducting organic salt synthesized in situ onto an overoxidized poly(pyrrole) (PPy(ox).) film is described. The TIF-TCNQ crystals grow through the nonconducting polypyrrole film (ensuring electrical connection to the underlying Pt electrode) and emerge from the film forming a treelike structure. The PPy(ox) film prevents the interfering substances from reaching the electrode surface. The sensor behavior can be modeled by assuming a direct reoxidation of the enzyme at the surface of the TTF-TCNQ crystals. A heterogeneous rate constant around 10(-6) - 10(-7) cm s(-1) has been estimated. The biosensor is nearly oxygen- and interference-free and when integrated in a flow injection system displays a remarkable sensitivity (70 nA/mM) and stability. PMID:12498183

  12. FIBER OPTIC BIOSENSOR FOR DNA DAMAGE

    EPA Science Inventory

    This paper describes a fiber optic biosensor for the rapid and sensitive detection of radiation-induced or chemically-induced oxidative DNA damage. The assay is based on the hybridization and temperature-induced dissociation (melting curves) of synthetic oligonucleotides. The...

  13. Application of the magnetoimpedance to biosensors

    NASA Astrophysics Data System (ADS)

    Song, Hoon; Park, Duck-gun

    2012-11-01

    A prototype of a giant magnetoimpedance (GMI) biosensor was designed and tested using an amorphous ribbon. The GMI response was measured with a suspension containing a CM01N/9077 bead from Bangs Laboratories. This bead was coated with streptavidin so that it could be used as biomolecular label with a specific antibody. The GMI change caused by the presence of the specific antibody was measured with a prototype biosensor designed with a measuring cell containing an amorphous CoFeBSi ribbon. The GMI was measured in a range of current frequencies from 0.1 to 10 MHz and at intensities of Irms = 5 mA. Commercial Bangs Laboratories beads were supplied as a suspension in phosphate-buffered saline. A maximum difference of 5% in the GMI ratio measured with and without magnetic beads was obtained at a frequency of 1 MHz and Irms = 5 mA. As some potential applications for the GMI biosensor and further directions, a magnetoimpedance biosensor for detecting the presence of magnetic nanoparticles after introducing a protein on the surface of the sensor has been developed and tested for a model system by using human P21 protein (antibody and antigen) and nonspecific magnetic nanoparticles.

  14. Methods for using redox liposome biosensors

    DOEpatents

    Cheng, Quan; Stevens, Raymond C.

    2002-01-01

    The present invention provides methods and compositions for detecting the presence of biologically-important analytes by using redox liposome biosensors. In particular, the present invention provides liposome/sol-gel electrodes suitable for the detection of a wide variety of organic molecules, including but not limited to bacterial toxins.

  15. Boar taint detection using parasitoid biosensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To evaluate the potential for a non-stinging wasp to be used as a biosensor in the pig industry, we trained wasps to 3 individual chemicals associated with boar taint. Training consisted of presenting the odors to hungry wasps while they were feeding on sugar. This associates the chemical with a fo...

  16. Clinical Assessment Applications of Ambulatory Biosensors

    ERIC Educational Resources Information Center

    Haynes, Stephen N.; Yoshioka, Dawn T.

    2007-01-01

    Ambulatory biosensor assessment includes a diverse set of rapidly developing and increasingly technologically sophisticated strategies to acquire minimally disruptive measures of physiological and motor variables of persons in their natural environments. Numerous studies have measured cardiovascular variables, physical activity, and biochemicals…

  17. Microbial Biosensors for Selective Detection of Disaccharides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven microbial strains were screened for their ability to detect disaccharides as components of Clark-type oxygen biosensors. Sensors responded to varying degrees to maltose, cellobiose, sucrose, and melibiose, but none responded strongly to lactose. Although microbial sensors are relatively nons...

  18. [Quantitative analysis of calibration dependence of biosensors].

    PubMed

    Borisov, I A; Lobanov, A V; Reshetilov, A N; Kurganov, B I

    2000-01-01

    Three-parameter Hill's equation, which is used in enzyme kinetics, was shown to applicable to calibration curves of both potentiometric (glucose, pesticides, urea, etc.) and amperometric (surfactants, biphenyl, etc.) biosensors. Possible causes of errors of analyte concentration measurements are discussed. PMID:10867941

  19. Cell-based biosensors in clinical chemistry.

    PubMed

    Kintzios, Spiridon E

    2007-10-01

    Cell-based biosensors represent the next revolution in medical diagnostics, offering a number of significant advantages, such as high speed, portability and low cost. The present review focuses on the most successful technologies used for the detection of ultra-low concentrations of bioactive analytes (such as metabolic markers and pathogens) in clinical samples. PMID:17979804

  20. Development and Applications of Portable Biosensors.

    PubMed

    Srinivasan, Balaji; Tung, Steve

    2015-08-01

    The significance of microfluidics-based and microelectromechanical systems-based biosensors has been widely acknowledged, and many reviews have explored their potential applications in clinical diagnostics, personalized medicine, global health, drug discovery, food safety, and forensics. Because health care costs are increasing, there is an increasing need to remotely monitor the health condition of patients by point-of-care-testing. The demand for biosensors for detection of biological warfare agents has increased, and research is focused on ways of producing small portable devices that would allow fast, accurate, and on-site detection. In the past decade, the demand for rapid and accurate on-site detection of plant disease diagnosis has increased due to emerging pathogens with resistance to pesticides, increased human mobility, and regulations limiting the application of toxic chemicals to prevent spread of diseases. The portability of biosensors for on-site diagnosis is limited due to various issues, including sample preparation techniques, fluid-handling techniques, the limited lifetime of biological reagents, device packaging, integrating electronics for data collection/analysis, and the requirement of external accessories and power. Many microfluidic, electronic, and biological design strategies, such as handling liquids in biosensors without pumps/valves, the application of droplet-based microfluidics, paper-based microfluidic devices, and wireless networking capabilities for data transmission, are being explored. PMID:25878051

  1. Biosensors for Whole-Cell Bacterial Detection

    PubMed Central

    Rushworth, Jo V.; Hirst, Natalie A.; Millner, Paul A.

    2014-01-01

    SUMMARY Bacterial pathogens are important targets for detection and identification in medicine, food safety, public health, and security. Bacterial infection is a common cause of morbidity and mortality worldwide. In spite of the availability of antibiotics, these infections are often misdiagnosed or there is an unacceptable delay in diagnosis. Current methods of bacterial detection rely upon laboratory-based techniques such as cell culture, microscopic analysis, and biochemical assays. These procedures are time-consuming and costly and require specialist equipment and trained users. Portable stand-alone biosensors can facilitate rapid detection and diagnosis at the point of care. Biosensors will be particularly useful where a clear diagnosis informs treatment, in critical illness (e.g., meningitis) or to prevent further disease spread (e.g., in case of food-borne pathogens or sexually transmitted diseases). Detection of bacteria is also becoming increasingly important in antibioterrorism measures (e.g., anthrax detection). In this review, we discuss recent progress in the use of biosensors for the detection of whole bacterial cells for sensitive and earlier identification of bacteria without the need for sample processing. There is a particular focus on electrochemical biosensors, especially impedance-based systems, as these present key advantages in terms of ease of miniaturization, lack of reagents, sensitivity, and low cost. PMID:24982325

  2. Fiber optic biosensor using aptamer as receptors

    NASA Astrophysics Data System (ADS)

    Yu, Shuqin; Cai, Xiaokun; Tan, Xianglin; Zhu, Yexiang; Lu, Bin

    2001-09-01

    Reagentless biosensor that can directly transducer molecular recognition to optical signal should potentiate the development of sensor array fora wide variety of analytes. Nucleic acid aptamer can bind ligand tightly and specifically with conformational change of aptamer, and can be used as a receptor in biosensor. We have therefore developed a fiber-optic biosensor by aptamer connected with molecular beacon. Molecular beacons consist of an oligonucleotide sequence containing complementary sequence sections at either end. These two sequence containing segments base pair with each other to form a hairpin shaped loop structure, the fluorophore and quencher were attached at 5 foot- and 3 foot-end of molecular beacon respectively. When thrombin binding to the stem-loop of molecular beacon aptamer, the pseudoknot structure was interrupted, resulting a release of fluorescence from quenching and a increase in fluorescence emission. This novel biosensor system in this project has a large potential and is specific and sensitivity. A similar strategy could be used to study other analytes such as protein and small molecules.

  3. Fiber optic-based regenerable biosensor

    DOEpatents

    Sepaniak, Michael J.; Vo-Dinh, Tuan

    1993-01-01

    A fiber optic-based regenerable biosensor. The biosensor is particularly suitable for use in microscale work in situ. In one embodiment, the biosensor comprises a reaction chamber disposed adjacent the distal end of a waveguide and adapted to receive therein a quantity of a sample containing an analyte. Leading into the chamber is a plurality of capillary conduits suitable for introducing into the chamber antibodies or other reagents suitable for selective interaction with a predetermined analyte. Following such interaction, the contents of the chamber may be subjected to an incident energy signal for developing fluorescence within the chamber that is detectable via the optical fiber and which is representative of the presence, i.e. concentration, of the selected analyte. Regeneration of the biosensor is accomplished by replacement of the reagents and/or the analyte, or a combination of these, at least in part via one or more of the capillary conduits. The capillary conduits extend from their respective terminal ends that are in fluid communication with the chamber, away from the chamber to respective location(s) remote from the chamber thereby permitting in situ location of the chamber and remote manipulation and/or analysis of the activity with the chamber.

  4. Recent Advances in Biosensor Technology for Potential Applications - An Overview.

    PubMed

    Vigneshvar, S; Sudhakumari, C C; Senthilkumaran, Balasubramanian; Prakash, Hridayesh

    2016-01-01

    Imperative utilization of biosensors has acquired paramount importance in the field of drug discovery, biomedicine, food safety standards, defense, security, and environmental monitoring. This has led to the invention of precise and powerful analytical tools using biological sensing element as biosensor. Glucometers utilizing the strategy of electrochemical detection of oxygen or hydrogen peroxide using immobilized glucose oxidase electrode seeded the discovery of biosensors. Recent advances in biological techniques and instrumentation involving fluorescence tag to nanomaterials have increased the sensitive limit of biosensors. Use of aptamers or nucleotides, affibodies, peptide arrays, and molecule imprinted polymers provide tools to develop innovative biosensors over classical methods. Integrated approaches provided a better perspective for developing specific and sensitive biosensors with high regenerative potentials. Various biosensors ranging from nanomaterials, polymers to microbes have wider potential applications. It is quite important to integrate multifaceted approaches to design biosensors that have the potential for diverse usage. In light of this, this review provides an overview of different types of biosensors being used ranging from electrochemical, fluorescence tagged, nanomaterials, silica or quartz, and microbes for various biomedical and environmental applications with future outlook of biosensor technology. PMID:26909346

  5. Synthesis and characterization of nanoparticles for electrochemical biosensor applications

    NASA Astrophysics Data System (ADS)

    Won, Yu-Ho

    Biosensors have been developed for detection, quantification, and monitoring of specific biomolecules or chemical species for environmental, clinical, and industrial fields. Nanoparticles, which can be functionalized by various materials, have attracted research interest in the electrochemical biosensors field due to their versatile physical and chemical properties. Thus, nanoparticles and nanocomposites have been widely investigated as a matrix for the electrochemical biosensors of the detection of various molecules. In this work, nanoparticles, including Fe3O4/silica core/shell nanocomposites, CaCO3-CdSe/ZnS/silica composites, Au nanocrystals, and Cu2O & Cu2O/Au particles, were synthesized and applied for the design of electrochemical biosensors. The goal of this research is to investigate novel nanoparticle-based platforms for the design of highly sensitive and stable biosensors. Biosensors can be categorized into enzyme-based biosensors and enzyme-free biosensors depending on whether or not enzymes are present in the system. Fe3O 4/silica core/shell nanocomposites and CaCO3-CdSe/ZnS/silica composites were used as material platforms to immobilize enzymes and fabricate enzyme-based electrochemical biosensors. On the other hand, Au nanocrystals, Cu2O, and Cu2O/Au particles, which display significant catalytic and electron transfer properties, were investigated in enzyme-free biosensor configurations. In addition, the morphology-dependent biosensing properties of Au nanocrystals, Cu2O, and Cu2O/Au particles were investigated.

  6. Future of biosensors: a personal view.

    PubMed

    Scheller, Frieder W; Yarman, Aysu; Bachmann, Till; Hirsch, Thomas; Kubick, Stefan; Renneberg, Reinhard; Schumacher, Soeren; Wollenberger, Ulla; Teller, Carsten; Bier, Frank F

    2014-01-01

    Biosensors representing the technological counterpart of living senses have found routine application in amperometric enzyme electrodes for decentralized blood glucose measurement, interaction analysis by surface plasmon resonance in drug development, and to some extent DNA chips for expression analysis and enzyme polymorphisms. These technologies have already reached a highly advanced level and need minor improvement at most. The dream of the "100-dollar" personal genome may come true in the next few years provided that the technological hurdles of nanopore technology or of polymerase-based single molecule sequencing can be overcome. Tailor-made recognition elements for biosensors including membrane-bound enzymes and receptors will be prepared by cell-free protein synthesis. As alternatives for biological recognition elements, molecularly imprinted polymers (MIPs) have been created. They have the potential to substitute antibodies in biosensors and biochips for the measurement of low-molecular-weight substances, proteins, viruses, and living cells. They are more stable than proteins and can be produced in large amounts by chemical synthesis. Integration of nanomaterials, especially of graphene, could lead to new miniaturized biosensors with high sensitivity and ultrafast response. In the future individual therapy will include genetic profiling of isoenzymes and polymorphic forms of drug-metabolizing enzymes especially of the cytochrome P450 family. For defining the pharmacokinetics including the clearance of a given genotype enzyme electrodes will be a useful tool. For decentralized online patient control or the integration into everyday "consumables" such as drinking water, foods, hygienic articles, clothing, or for control of air conditioners in buildings and cars and swimming pools, a new generation of "autonomous" biosensors will emerge. PMID:24196315

  7. Enhancing the Detection Limit of Nanoscale Biosensors via Topographically Selective Functionalization

    PubMed Central

    Lifson, Mark A.; Roy, Dhrubajyoti Basu; Miller, Benjamin L.

    2014-01-01

    Nanoscale biosensors have remarkable theoretical sensitivities, but often suffer from sub-optimal limits of detection in practice. This is in part because the sensing area of nanoscale sensors is orders of magnitude smaller than the total device substrate. Current strategies to immobilize probes (capture molecules) functionalize both sensing and non-sensing regions, leading to target depletion and diminished limits of detection. The difference in topography between these regions on nanoscale biosensors offers a way to selectively address only the sensing area. We developed a bottom-up, topographically selective approach employing self-assembled poly(N-isopropylacrylamide) (PNIPAM) hydrogel nanoparticles as a mask to preferentially bind target to only the active sensing region of a photonic crystal (PhC) biosensor. This led to over one order of magnitude improvement in the limit of detection for the device, in agreement with finite element simulations. Since the sensing elements in many nanoscale sensors are topographically distinct, this approach should be widely applicable. PMID:24372197

  8. A potentiometric biosensor for the detection of notch 3 using functionalized ZnO nanorods.

    PubMed

    Ibupoto, Z H; Khun, K; Liu, X; Willander, M

    2014-09-01

    The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0 ) μg/mL with a sensitivity of 23.15 ± 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s. PMID:25924320

  9. Late Quaternary Activity and Seismogenic Potential of the Gonave Microplate: Plantain Garden Strike-Slip Fault Zone of Eastern Jamaica

    NASA Astrophysics Data System (ADS)

    Mann, P.; Prentice, C.; King, W.; Demets, C.; Wiggins-Grandison, M.; Benford, B.

    2008-12-01

    At the longitude of Jamaica, Caribbean (Carib)-North America (Noam) plate motion of 19 ± 2 mm/a is carried by two parallel, left-lateral strike-slip faults, the Oriente fault zone, immediately south of Cuba, and the Enriquillo-Plantain Garden fault zone (EPGFZ), which lies 100-150 km further south. It has been postulated that the lithosphere between these faults constitutes an independent Gonave microplate that has formed in response to the ongoing collision between the leading edge of Carib in Hispaniola and the Bahama carbonate platform. GPS measurements in Jamaica and Hispanola is supportive of the microplate hypothesis and indicates that roughly half of Carib-Noam plate motion (8-14 mm/a) is carried by the EPGFZ of southern Hispaniola and eastern Jamaica. This study applies geomorphic and paleoseismic methods as a direct test of the activity and amount of microplate motion carried on the Plantain Garden fault segment of eastern Hispaniola and how this motion is distributed across a large restraining bend that has formed the island of Jamaica since the late Miocene. The EPFZ curves gently to the northeast and forming a steep mountain front to the Blue Mountains restraining bend with elevations up to 2200 m. Geomorphic fault-related features along the mountain front fault zone include left-laterally deflected rivers and streams, but no small scale features indicative of Holocene activity. River and stream deflections range from 0.1 to 0.5 km. We identified and trenched the most active trace of the mountain front fault at the Morant River where the fault is characterized by a 1.5-m-wide sub-vertical fault zone juxtaposing sheared alluvium and fault Cretaceous basement rocks This section is overlain by a 6-m-thick fluvial terrace. Trenching in the unfaulted terrace immediately overlying the fault trace revealed radiocarbon and OSL ages ranging from 20 to 21 ka that are consistent with a prominent unfaulted alluvial fan along the projection of this fault 1.5 km to

  10. Metabolic effects of azoxystrobin and kresoxim-methyl against Fusarium kyushuense examined using the Biolog FF MicroPlate.

    PubMed

    Wang, Hancheng; Wang, Jin; Chen, Qingyuan; Wang, Maosheng; Hsiang, Tom; Shang, Shenghua; Yu, Zhihe

    2016-06-01

    Azoxystrobin and kresoxim-methyl are strobilurin fungicides, and are effective in controlling many plant diseases, including Fusarium wilt. The mode of action of this kind of chemical is inhibition of respiration. This research investigated the sensitivities of Fusarium kyushuense to azoxystrobin and kresoxim-methyl, and to the alternative oxidase inhibitor salicylhydroxamic acid (SHAM). The Biolog FF MicroPlate is designed to examine substrate utilization and metabolic profiling of micro-organisms, and was used here to study the activity of azoxystrobin, kresoxim-methyl and SHAM against F. kyushuense. Results presented that azoxystrobin and kresoxim-methyl strongly inhibited conidial germination and mycelial growth of F. kyushuense, with EC50 values of 1.60 and 1.79μgml(-1), and 6.25 and 11.43μgml(-1), respectively; while not for SHAM. In the absence of fungicide, F. kyushuense was able to metabolize 91.6% of the tested carbon substrates, including 69 effectively and 18 moderately. SHAM did not inhibit carbon substrate utilization. Under the selective pressure of azoxystrobin and kresoxim-methyl during mycelial growth (up to 100μgml(-1)) and conidial germination (up to 10μgml(-1)), F. kyushuense was unable to metabolize many substrates in the Biolog FF MicroPlate; while especially for carbon substrates in glycolysis and tricarboxylic acid cycle, with notable exceptions such as β-hydroxybutyric acid, y-hydroxybutyric acid, α-ketoglutaric acid, α-d-glucose-1-phosphate, d-saccharic acid and succinic acid in the mycelial growth stage, and β-hydroxybutyric acid, y-hydroxybutyric acid, α-ketoglutaric acid, tween-80, arbutin, dextrin, glycerol and glycogen in the conidial germination stage. This is a new finding for some effect of azoxystrobin and kresoxim-methyl on carbon substrate utilization related to glycolysis and tricarboxylic acid cycle and other carbons, and may lead to future applications of Biolog FF MicroPlate for metabolic effects of other

  11. Fabrication of Optical Devices Based on Printable Photonics Technology and Its Application for Biosensor

    NASA Astrophysics Data System (ADS)

    Endo, Tatsuro; Okuda, Norimichi; Yanagida, Yasuko; Tanaka, Satoru; Hatsuzawa, Takeshi

    The specific optical characteristics which can be observed nanostructured optical device have great potentials for applying to several applications such as lifescience, optical communications, and data storage. Application of nanostrcutured optical device to industry, we suggest “printable photonics technology” for fabrication of nanostructured optical device based on nanoimprint lithography (NIL). In this study, using printable photonics technology, fabrication of flexible photonic crystal (PC) and its application for biosensor was performed. Using printable photonics technology-based PC for biosensing application, high sensitive detection of protein adsorption (detection limit: 1 pg/ml) could be detected.

  12. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    SciTech Connect

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; Soares, Alexei S.

    2014-11-28

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. Ultimately, the results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.

  13. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    PubMed Central

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; Soares, Alexei S.

    2014-01-01

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. The results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations. PMID:25484231

  14. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    DOE PAGESBeta

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; et al

    2014-11-28

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under differentmore » conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. Ultimately, the results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.« less

  15. Modelling Amperometric Biosensors Based on Chemically Modified Electrodes

    PubMed Central

    Baronas, Romas; Kulys, Juozas

    2008-01-01

    The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate.

  16. A general strategy to construct small molecule biosensors in eukaryotes

    DOE PAGESBeta

    Feng, Justin; Jester, Benjamin W.; Tinberg, Christine E.; Mandell, Daniel J.; Antunes, Mauricio S.; Chari, Raj; Morey, Kevin J.; Rios, Xavier; Medford, June I.; Church, George M.; et al

    2015-12-29

    Biosensors for small molecules can be used in applications that range from metabolic engineering to orthogonal control of transcription. Here, we produce biosensors based on a ligand-binding domain (LBD) by using a method that, in principle, can be applied to any target molecule. The LBD is fused to either a fluorescent protein or a transcriptional activator and is destabilized by mutation such that the fusion accumulates only in cells containing the target ligand. We illustrate the power of this method by developing biosensors for digoxin and progesterone. Addition of ligand to yeast, mammalian, or plant cells expressing a biosensor activatesmore » transcription with a dynamic range of up to ~100-fold. We use the biosensors to improve the biotransformation of pregnenolone to progesterone in yeast and to regulate CRISPR activity in mammalian cells. This work provides a general methodology to develop biosensors for a broad range of molecules in eukaryotes.« less

  17. DNA probe functionalized QCM biosensor based on gold nanoparticle amplification for Bacillus anthracis detection.

    PubMed

    Hao, Rong-Zhang; Song, Hong-Bin; Zuo, Guo-Min; Yang, Rui-Fu; Wei, Hong-Ping; Wang, Dian-Bing; Cui, Zong-Qiang; Zhang, ZhiPing; Cheng, Zhen-Xing; Zhang, Xian-En

    2011-04-15

    The rapid detection of Bacillus anthracis, the causative agent of anthrax disease, has gained much attention since the anthrax spore bioterrorism attacks in the United States in 2001. In this work, a DNA probe functionalized quartz crystal microbalance (QCM) biosensor was developed to detect B. anthracis based on the recognition of its specific DNA sequences, i.e., the 168 bp fragment of the Ba813 gene in chromosomes and the 340 bp fragment of the pag gene in plasmid pXO1. A thiol DNA probe was immobilized onto the QCM gold surface through self-assembly via Au-S bond formation to hybridize with the target ss-DNA sequence obtained by asymmetric PCR. Hybridization between the target DNA and the DNA probe resulted in an increase in mass and a decrease in the resonance frequency of the QCM biosensor. Moreover, to amplify the signal, a thiol-DNA fragment complementary to the other end of the target DNA was functionalized with gold nanoparticles. The results indicate that the DNA probe functionalized QCM biosensor could specifically recognize the target DNA fragment of B. anthracis from that of its closest species, such as Bacillus thuringiensis, and that the limit of detection (LOD) reached 3.5 × 10(2)CFU/ml of B. anthracis vegetative cells just after asymmetric PCR amplification, but without culture enrichment. The DNA probe functionalized QCM biosensor demonstrated stable, pollution-free, real-time sensing, and could find application in the rapid detection of B. anthracis. PMID:21315574

  18. Neutral red cytotoxicity assays for assessing in vivo carbon nanotube ecotoxicity in mussels--Comparing microscope and microplate methods.

    PubMed

    Miller, M A; Bankier, C; Al-Shaeri, M A M; Hartl, M G J

    2015-12-30

    The purpose of the present study was to compare two neutral red retention methods, the more established but very labour-intensive microscope method (NRR) against the more recently developed microplate method (NRU). The intention was to explore whether the sample volume throughput could be increased and potential operator bias avoided. Mussels Mytilus sp. were exposed in vivo to 50, 250 and 500 μg L(-1) single (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). Using the NRR method, SWCNTs and MWCNTs caused concentration dependent decreases in neutral red retention time. However, a concentration dependent decrease in optical density was not observed using the NRU method. We conclude that the NRU method is not sensitive enough to assess carbon nanotube ecotoxicity in vivo in environmentally relevant media, and recommend using the NRR method. PMID:26549297

  19. High-throughput genotyping using horizontal polyacrylamide gels with wells arranged for microplate array diagonal gel electrophoresis (MADGE).

    PubMed

    Day, I N; Humphries, S E; Richards, S; Norton, D; Reid, M

    1995-11-01

    Genotyping (typing of genetic variation) typically involves PCR followed by an allele-specific oligonucleotide-binding assay, restriction enzyme digest or direct check of the outcome of a PCR designed to distinguish genotype. Electrophoresis can resolve "bound" from "free" oligonucleotide, as well as resolve PCR fragments and digests, but it is traditionally regarded as cumbersome and laborious in comparison with solution assays. Here we describe simple horizontal polyacrylamide gels which can receive a 96-well array of samples directly, which can be stacked in tanks and which are bound to a robust support of glass. The line of electrophoresis is on a 71.6 degree diagonal relative to the columns of the array (microplate array diagonal gel electrophoresis [MADGE]). Several thousand reactions can conveniently be analyzed in a shoebox-sized apparatus in a couple of hours. High resolution is achieved in the range of 20-1000 bp, information processing is simplified and automation is possible. PMID:8588924

  20. Microplate-based screening for small molecule inhibitors of neuropilin-2/vascular endothelial growth factor-C interactions.

    PubMed

    Parker, Matthew W; Vander Kooi, Craig W

    2014-05-15

    Vascular endothelial growth factor-C (VEGF-C) is a secreted growth factor essential for lymphangiogenesis. VEGF-C functions in both physiological and pathological lymphangiogenesis, particularly in tumor metastasis, making it an attractive therapeutic target. Members of two families of cell surface receptors transduce VEGF-C signals: neuropilin-2 (Nrp2) and VEGF-receptor (VEGFR)-2/3. Nrp2 is a promising target for inhibition because it is highly expressed in lymphatic vessels. Here we describe a microplate-based assay for discovery of VEGF-C/Nrp2 inhibitors. We optimize this assay for use in screening an inhibitor library and identify three novel Nrp2/VEGF-C binding inhibitors from the National Institutes of Health (NIH) Clinical Collection small molecule library. PMID:24583243

  1. Measuring intracellular calcium dynamics of HeLa cells exposed to nitric oxide by microplate fluorescence reader

    NASA Astrophysics Data System (ADS)

    Huang, Yimei; Chen, Jiangxu; Yang, Hongqin; Zheng, Liqin; Wang, Yuhua; Li, Hui; Xie, Shusen

    2012-12-01

    Nitric oxide (NO) has been reported to have the ability to promote or inhibit the proliferation and metastasis of cancer cells. It appears to have an effect on inducing calcium transient, which participates in essential cellular signaling in the physiological and pathological processes. Our work was intended to study the effects of exogenous NO on intracellular calcium dynamics of HeLa cells with Fluo-3, a calcium fluorescent indicator by microplate fluorescence reader. The results showed that after NO donor was injected into the wells, intracellular Ca2+ fluorescence intensity increased significantly compared with that of control group. Furthermore, the calcium transient activated by NO was mainly due to the calcium release from intracellular calcium stores. These would be helpful to further recognize the role of NO involved in cancer cell proliferation and metastasis.

  2. A Sensitive Microplate Assay for Lipase Activity Measurement Using Olive Oil Emulsion Substrate: Modification of the Copper Soap Colorimetric Method.

    PubMed

    Mustafa, Ahmad; Karmali, Amin; Abdelmoez, Wael

    2016-01-01

    The present work involves a sensitive high-throughput microtiter plate based colorimetric assay for estimating lipase activity using cupric acetate pyridine reagent (CAPR). In the first approach, three factors two levels factorial design methodology was used to evaluate the interactive effect of different parameters on the sensitivity of the assay method. The optimization study revealed that the optimum CAPR concentration was 7.5% w/v, the optimum solvent was heptane and the optimum CAPR pH was 6. In the second approach, the optimized colorimetric microplate assay was used to measure lipase activity based on enzymatic hydrolysis of olive oil emulsion substrate at 37°C and 150 rpm. The emulsion substrates were formulated by using olive oil, triton X-100 (10% v/v in pH 8) and sodium phosphate buffer of pH 8 in ratio of 1:1:1 in the case of Candida sp. lipase. While in the case of immobilized lipozyme RMIM, The emulsion substrates were formulated by using olive oil, triton X-100 (1% v/v in pH 8) and sodium phosphate buffer of pH 8 in ratio of 2:1:1. Absorbance was measured at 655 nm. The stability of this assay (in terms of colored heptane phase absorbance readings) retained more than 92.5% after 24 h at 4°C compared to the absorbance readings measured at zero time. In comparison with other lipase assay methods, beside the developed sensitivity, the reproducibility and the lower limit of detection (LOD) of the proposed method, it permits analyzing of 96 samples at one time in a 96-well microplate. Furthermore, it consumes small quantities of chemicals and unit operations. PMID:27581492

  3. A universally calibrated microplate ferric reducing antioxidant power (FRAP) assay for foods and applications to Manuka honey.

    PubMed

    Bolanos de la Torre, Amparo Angelica S; Henderson, Terence; Nigam, Poonam Singh; Owusu-Apenten, Richard K

    2015-05-01

    The ferric reducing antioxidant power (FRAP) assay was recently adapted to a microplate format. However, microplate-based FRAP (mFRAP) assays are affected by sample volume and composition. This work describes a calibration process for mFRAP assays which yields data free of volume effects. From the results, the molar absorptivity (ε) for the mFRAP assay was 141,698 M(-1) cm(-1) for gallic acid, 49,328 M(-1) cm(-1) for ascorbic acid, and 21,606 M(-1) cm(-1) for ammonium ferrous sulphate. The significance of ε (M(-1) cm(-1)) is discussed in relation to mFRAP assay sensitivity, minimum detectable concentration, and the dimensionless FRAP-value. Gallic acid showed 6.6 mol of Fe(2+) equivalents compared to 2.3 mol of Fe(+2) equivalents for ascorbic acid. Application of the mFRAP assay to Manuka honey samples (rated 5+, 10+, 15+, and 18+ Unique Manuka Factor; UMF) showed that FRAP values (0.54-0.76 mmol Fe(2+) per 100g honey) were strongly correlated with UMF ratings (R(2)=0.977) and total phenols content (R(2) = 0.982)whilst the UMF rating was correlated with the total phenols (R(2) = 0.999). In conclusion, mFRAP assay results were successfully standardised to yield data corresponding to 1-cm spectrophotometer which is useful for quality assurance purposes. The antioxidant capacity of Manuka honey was found to be directly related to the UMF rating. PMID:25529660

  4. Early implications of the COCONet GPS velocity field for studies of plate and microplate motions in the Caribbean

    NASA Astrophysics Data System (ADS)

    DeMets, C.

    2013-05-01

    Now entering their 3rd decade, GPS measurements in the Caribbean region have been used to study a wide range of tectonic topics such as the movement of the Caribbean plate relative to North and South America, earthquake cycle effects along the seismically hazardous Caribbean plate boundary faults, and microplate interactions along the complexly deforming Caribbean plate boundaries. The construction of COCONet stands out as the most significant-ever one-time advance in GPS-MET infrastructure in the Caribbean region due to its standardized GPS-MET equipment, its open access to real-time data, and its expansion of coverage relative to pre-existing GPS stations. In this talk, I will show an up-to-date Caribbean region velocity field derived using the most recent version of GIPSY software (release 6.1), the latest satellite orbit products, single-station ambiguity resolution, and a consistent realization of the Caribbean plate reference frame. Consisting of several hundred site velocities, the new velocity field clearly defines how the crust responds to east-to-west changes in the geometry of the Caribbean-North America plate boundary, including the profound effect of the oblique collision zone between the Bahama platform and northern edge of the Caribbean plate. I will discuss implications of the still-maturing COCONet GPS velocities for ongoing studies of Caribbean plate motion and plate rigidity and will also discuss applications of COCONet velocities for testing recently published kinematic estimates for the movements of the Gonave, Puerto Rico, Hispaniola, and southern Jamaica microplates.

  5. Cellphone-Based Hand-Held Microplate Reader for Point-of-Care Testing of Enzyme-Linked Immunosorbent Assays.

    PubMed

    Berg, Brandon; Cortazar, Bingen; Tseng, Derek; Ozkan, Haydar; Feng, Steve; Wei, Qingshan; Chan, Raymond Yan-Lok; Burbano, Jordi; Farooqui, Qamar; Lewinski, Michael; Di Carlo, Dino; Garner, Omai B; Ozcan, Aydogan

    2015-08-25

    Standard microplate based enzyme-linked immunosorbent assays (ELISA) are widely utilized for various nanomedicine, molecular sensing, and disease screening applications, and this multiwell plate batched analysis dramatically reduces diagnosis costs per patient compared to nonbatched or nonstandard tests. However, their use in resource-limited and field-settings is inhibited by the necessity for relatively large and expensive readout instruments. To mitigate this problem, we created a hand-held and cost-effective cellphone-based colorimetric microplate reader, which uses a 3D-printed opto-mechanical attachment to hold and illuminate a 96-well plate using a light-emitting-diode (LED) array. This LED light is transmitted through each well, and is then collected via 96 individual optical fibers. Captured images of this fiber-bundle are transmitted to our servers through a custom-designed app for processing using a machine learning algorithm, yielding diagnostic results, which are delivered to the user within ∼1 min per 96-well plate, and are visualized using the same app. We successfully tested this mobile platform in a clinical microbiology laboratory using FDA-approved mumps IgG, measles IgG, and herpes simplex virus IgG (HSV-1 and HSV-2) ELISA tests using a total of 567 and 571 patient samples for training and blind testing, respectively, and achieved an accuracy of 99.6%, 98.6%, 99.4%, and 99.4% for mumps, measles, HSV-1, and HSV-2 tests, respectively. This cost-effective and hand-held platform could assist health-care professionals to perform high-throughput disease screening or tracking of vaccination campaigns at the point-of-care, even in resource-poor and field-settings. Also, its intrinsic wireless connectivity can serve epidemiological studies, generating spatiotemporal maps of disease prevalence and immunity. PMID:26159546

  6. Microbial Biosensors: Engineered Microorganisms as the Sensing Machinery

    PubMed Central

    Park, Miso; Tsai, Shen-Long; Chen, Wilfred

    2013-01-01

    Whole-cell biosensors are a good alternative to enzyme-based biosensors since they offer the benefits of low cost and improved stability. In recent years, live cells have been employed as biosensors for a wide range of targets. In this review, we will focus on the use of microorganisms that are genetically modified with the desirable outputs in order to improve the biosensor performance. Different methodologies based on genetic/protein engineering and synthetic biology to construct microorganisms with the required signal outputs, sensitivity, and selectivity will be discussed. PMID:23648649

  7. Label-Free Impedance Biosensors: Opportunities and Challenges

    PubMed Central

    Daniels, Jonathan S.; Pourmand, Nader

    2007-01-01

    Impedance biosensors are a class of electrical biosensors that show promise for point-of-care and other applications due to low cost, ease of miniaturization, and label-free operation. Unlabeled DNA and protein targets can be detected by monitoring changes in surface impedance when a target molecule binds to an immobilized probe. The affinity capture step leads to challenges shared by all label-free affinity biosensors; these challenges are discussed along with others unique to impedance readout. Various possible mechanisms for impedance change upon target binding are discussed. We critically summarize accomplishments of past label-free impedance biosensors and identify areas for future research. PMID:18176631

  8. Non-Invasive Optical Biosensor for Probing Cell Signaling

    PubMed Central

    Fang, Ye

    2007-01-01

    Cell signaling mediated through a cellular target is encoded by spatial and temporal dynamics of downstream signaling networks. The coupling of temporal dynamics with spatial gradients of signaling activities guides cellular responses upon stimulation. Monitoring the integration of cell signaling in real time, if realized, would provide a new dimension for understanding cell biology and physiology. Optical biosensors including resonant waveguide grating (RWG) biosensor manifest a physiologically relevant and integrated cellular response related to dynamic redistribution of cellular matters, thus providing a non-invasive means for cell signaling study. This paper reviews recent progresses in biosensor instrumentation, and theoretical considerations and potential applications of optical biosensors for whole cell sensing.

  9. In-situ monitoring of biologically active solar UV-B radiation: a new biosensor of vitamin D synthetic capacity

    NASA Astrophysics Data System (ADS)

    Terenetskaya, Irina P.; Gvozdovskyy, I. A.

    2001-06-01

    The new biosensor of vitamin D synthetic capacity of solar/artificial UV-B radiation is based on liquid crystal with provitamin D dopant. Nematic liquid crystals (LC-805, ZLI-1695) are converted into induced cholesteric phase using photosensitive steroid biomolecules of provitamin D3 (7- dehydrocholesterol). During UV exposure remarkable decrease in the number of the Cano-Grandjean stripes has been observed in the wedge-like cell as a result of UV initiated photoisomerization of provitamin D3 that changed helical twisting power of the dopant molecules.

  10. Use of a parasitic wasp as a biosensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Screening cargo for illicit substances is still in need of high-throughput inspection systems that can rapidly screen and accurately identify suspicious cargo. Here we investigate the ability of a parasitic wasp, Microplitis croceipes to detect and respond to methyl benzoate, the volatile component ...

  11. Recent advances in graphene-based biosensors.

    PubMed

    Kuila, Tapas; Bose, Saswata; Khanra, Partha; Mishra, Ananta Kumar; Kim, Nam Hoon; Lee, Joong Hee

    2011-08-15

    A detailed overview towards the advancement of graphene based biosensors has been reviewed. The large surface area and excellent electrical conductivity of graphene allow it to act as an "electron wire" between the redox centers of an enzyme or protein and an electrode's surface. Rapid electron transfer facilitates accurate and selective detection of biomolecules. This review discusses the application of graphene for the detection of glucose, Cyt-c, NADH, Hb, cholesterol, AA, UA, DA, and H(2)O(2). GO and RGO have been used for the fabrication of heavy metal ion sensors, gas sensors, and DNA sensors. Graphene based FETs have also been discussed in details. In all these cases, the biosensors performed well with low working potentials, high sensitivities, low detection limits, and long-term stabilities. PMID:21683572

  12. Microbial fuel cells for biosensor applications.

    PubMed

    Yang, Huijia; Zhou, Minghua; Liu, Mengmeng; Yang, Weilu; Gu, Tingyue

    2015-12-01

    Microbial fuel cells (MFCs) face major hurdles for real-world applications as power generators with the exception of powering small sensor devices. Despite tremendous improvements made in the last two decades, MFCs are still too expensive to build and operate and their power output is still too small. In view of this, in recently years, intensive researches have been carried out to expand the applications into other areas such as acid and alkali production, bioremediation of aquatic sediments, desalination and biosensors. Unlike power applications, MFC sensors have the immediate prospect to be practical. This review covers the latest developments in various proposed biosensor applications using MFCs including monitoring microbial activity, testing biochemical oxygen demand, detection of toxicants and detection of microbial biofilms that cause biocorrosion. PMID:26272393

  13. Surface modified amorphous ribbon based magnetoimpedance biosensor.

    PubMed

    Kurlyandskaya, Galina V; Fal Miyar, Vanessa

    2007-04-15

    Magnetoimpedance (MI) changes due to surface modification of the sensitive element caused by human urine, were studied with the aim of creating a robust biosensor working on a principle of electrochemical magnetoimpedance spectroscopy. A biosensor prototype with an as-quenched amorphous ribbon sensitive element was designed and calibrated for a frequency range of 0.5-10 MHz at a current intensity of 60 mA. Measurements as a function of the exposure time were made both in a regime where chemical surface modification and MI measurements were separated as well as in a regime where they were done simultaneously. The MI variation was explained by the change of the surface magnetic anisotropy. It was shown that the magnetoimpedance effect can be successfully employed as a new option to probe the electric features of the Fe(5)Co(70)Si(15)B(10) amorphous ribbon magnetic electrode surface modified by human urine. PMID:16914305

  14. Bioconjugation and stabilisation of biomolecules in biosensors

    PubMed Central

    Drago, Guido A.

    2016-01-01

    Suitable bioconjugation strategies and stabilisation of biomolecules on electrodes is essential for the development of novel and commercially viable biosensors. In the present review, the functional groups that comprise the selectable targets for practical bioconjugation methods are discussed. We focus on describing the most common immobilisation techniques used in biosensor construction, which are classified into irreversible and reversible methods. Concerning the stability of proteins, the two main types of stability may be defined as (i) storage or shelf stability, and (ii) operational stability. Both types of stability are explained, as well as the introduction of an electrophoretic technique for predicting protein–polymer interactions. In addition, solution and dry stabilisation as well as stabilisation using the covalent immobilisation of proteins are discussed including possible factors that influence stability. Finally, the integration of nanomaterials, such as magnetic particles, with protein immobilisation is discussed in relation to protein stability studies. PMID:27365036

  15. Bioconjugation and stabilisation of biomolecules in biosensors.

    PubMed

    Liébana, Susana; Drago, Guido A

    2016-06-30

    Suitable bioconjugation strategies and stabilisation of biomolecules on electrodes is essential for the development of novel and commercially viable biosensors. In the present review, the functional groups that comprise the selectable targets for practical bioconjugation methods are discussed. We focus on describing the most common immobilisation techniques used in biosensor construction, which are classified into irreversible and reversible methods. Concerning the stability of proteins, the two main types of stability may be defined as (i) storage or shelf stability, and (ii) operational stability. Both types of stability are explained, as well as the introduction of an electrophoretic technique for predicting protein-polymer interactions. In addition, solution and dry stabilisation as well as stabilisation using the covalent immobilisation of proteins are discussed including possible factors that influence stability. Finally, the integration of nanomaterials, such as magnetic particles, with protein immobilisation is discussed in relation to protein stability studies. PMID:27365036

  16. Modelling Carbon Nanotubes-Based Mediatorless Biosensor

    PubMed Central

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  17. Modelling carbon nanotubes-based mediatorless biosensor.

    PubMed

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  18. Recent advances in biosensor based endotoxin detection.

    PubMed

    Das, A P; Kumar, P S; Swain, S

    2014-01-15

    Endotoxins also referred to as pyrogens are chemically lipopolysaccharides habitually found in food, environment and clinical products of bacterial origin and are unavoidable ubiquitous microbiological contaminants. Pernicious issues of its contamination result in high mortality and severe morbidities. Standard traditional techniques are slow and cumbersome, highlighting the pressing need for evoking agile endotoxin detection system. The early and prompt detection of endotoxin assumes prime importance in health care, pharmacological and biomedical sectors. The unparalleled recognition abilities of LAL biosensors perched with remarkable sensitivity, high stability and reproducibility have bestowed it with persistent reliability and their possible fabrication for commercial applicability. This review paper entails an overview of various trends in current techniques available and other possible alternatives in biosensor based endotoxin detection together with its classification, epidemiological aspects, thrust areas demanding endotoxin control, commercially available detection sensors and a revolutionary unprecedented approach narrating the influence of omics for endotoxin detection. PMID:23934306

  19. Biosensors and other medical and environmental probes

    SciTech Connect

    Jacobson, K.B.

    1996-12-31

    The author presents a overview of work at Oak Ridge National Laboratory directed toward the development of biosensors which can be used to monitor for an array of medical and environmental effects. The article describes the variety of problems which have been addressed by development of such sensors, and the range of staff who have been actively involved in this effort. The first such sensor developed at ORNL was an optical fiber whose end was treated with an antibody which would react with the carcinogen benzo(a)pyrene (BaP). Section titles from the article provide an idea of the breadth of applications addressed: medical telesensors; microcantilevers; detecting cancer and health abnormalities; bioreporters; miniaturized devices; biosensors and DNA analysis; lipids in bacteria and human fingerprints; and anthropometry.

  20. Biosensors for waterborne viruses: Detection and removal.

    PubMed

    Altintas, Zeynep; Gittens, Micah; Pocock, Jack; Tothill, Ibtisam E

    2015-08-01

    Detection of waterborne viruses is important to eliminate and control their harmful effect as pathogens. Hence, the use of rapid and sensitive detection technologies is critically important as they can aid in investigating outbreaks and help in developing prevention strategies. To date range of viruses can contaminate drinking water sources, causing illnesses such as diarrhoea, pneumonia and gastroenteritis which can result in death. Due to their small size (nm) their complete removal from water can be difficult with current water treatment processes while being resistant to disinfectants. Available techniques for virus detection include filtration technologies, enzyme-linked immunosorbent assays and polymerase chain reaction. Although each technique has limitations, the use of biosensor technology with smart affinity materials and nanomaterials can show great potential in sensing viruses in water samples. This review reports on the latest technologies used for waterborne virus removal and detection with focus on rapid detection using biosensors. PMID:26005094

  1. A portable array biosensor for food safety

    NASA Astrophysics Data System (ADS)

    Golden, Joel P.; Ngundi, Miriam M.; Shriver-Lake, Lisa C.; Taitt, Chris R.; Ligler, Frances S.

    2004-11-01

    An array biosensor developed for simultaneous analysis of multiple samples has been utilized to develop assays for toxins and pathogens in a variety of foods. The biochemical component of the multi-analyte biosensor consists of a patterned array of biological recognition elements immobilized on the surface of a planar waveguide. A fluorescence assay is performed on the patterned surface, yielding an array of fluorescent spots, the locations of which are used to identify what analyte is present. Signal transduction is accomplished by means of a diode laser for fluorescence excitation, optical filters and a CCD camera for image capture. A laptop computer controls the miniaturized fluidics system and image capture. Results for four mycotoxin competition assays in buffer and food samples are presented.

  2. Replaceable Microfluidic Cartridges for a PCR Biosensor

    NASA Technical Reports Server (NTRS)

    Francis, Kevin; Sullivan, Ron

    2005-01-01

    The figure depicts a replaceable microfluidic cartridge that is a component of a miniature biosensor that detects target deoxyribonucleic acid (DNA) sequences. The biosensor utilizes (1) polymerase chain reactions (PCRs) to multiply the amount of DNA to be detected, (2) fluorogenic polynucleotide probe chemicals for labeling the target DNA sequences, and (3) a high-sensitivity epifluorescence-detection optoelectronic subsystem. Microfluidics is a relatively new field of device development in which one applies techniques for fabricating microelectromechanical systems (MEMS) to miniature systems for containing and/or moving fluids. Typically, microfluidic devices are microfabricated, variously, from silicon or polymers. The development of microfluidic devices for applications that involve PCR and fluorescence-based detection of PCR products poses special challenges

  3. Amperometric biosensors based on carbon composite transducers

    NASA Astrophysics Data System (ADS)

    Lu, Fang

    1998-12-01

    Much current work in analytical chemistry is devoted to design of biosensors. One particular area in this field is the development of enzyme-based amperometric biosensors for the quantitative determination of a series of substrates in clinical, environmental, industrial and agricultural significance. This dissertation focuses on the design of improved amperometric biosensors based on carbon composite transducers. The use of metallized carbons as transducer materials results in remarkably selective amperometric biosensors. Such enzyme-based transducers eliminate major electroactive interferences, and hence circumvent the need for mediators or membrane barriers. The remarkable selectivity of metal-dispersed carbons is attributed to their strong, preferential, electrocatalytic capacity towards the reductive detection of biologically-generated hydrogen peroxide. Such electrocatalytic activity allows metal-dispersed biosensors to be operated at the optimal potential region between +0.1 and -0.2 V, where the unwanted reactions are neglected resulting in the lowest noise level. Several new materials (e.g., ruthenium on carbon, rhodium on carbon, etc.) and constructions (e.g., carbon fiber, electrochemical co-deposition transducer, etc.) were applied in the development of novel enzyme-based transducers in order to improve the selectivity and applicability of amperometric biosensors. The susceptibility of first-generation oxidase amperometric biosensing to oxygen fluctuations can be improved by using oxygen-rich fluorocarbons as the pasting binders in carbon paste enzyme transducers. Such binders provide an internal supply of oxygen resulting in efficient detection in oxygen-deficit conditions. In particular, the use of poly-chlorotrifluorethylene (Kel-F) oil as carbon paste binder results in a well-defined response and an identical signal up to 40 mM glucose in both the presence and absence of oxygen. Comparing with mediated or wired enzyme-based transducers, such internal

  4. Alps, Carpathians and Dinarides-Hellenides: about plates, micro-plates and delaminated crustal blocks

    NASA Astrophysics Data System (ADS)

    Schmid, Stefan

    2014-05-01

    Before the onset of Europe-Africa continental collision in the Dinarides-Hellenides (around 60Ma) and in the Alps and Western Carpathians (around 35 Ma), and at a large scale, the dynamics of orogenic processes in the Mediterranean Alpine chains were governed by Europe-Africa plate convergence leading to the disappearance of large parts of intervening oceanic lithosphere, i.e. the northern branch of Neotethys along the Sava-Izmir-Ankara suture and Alpine Tethys along the Valais-Magura suture (Schmid et al. 2008). In spite of this, two major problems concerning the pre-collisional stage are still poorly understood: (1) by now we only start to understand geometry, kinematics and dynamics of the along-strike changes in the polarity of subduction between Alps-Carpathians and Dinarides-Hellenides, and (2) it is not clear yet during exactly which episodes and to what extent intervening rifted continental fragments such as, for example, Iberia-Briançonnais, Tisza, Dacia, Adria-Taurides moved independently as micro-plates, and during which episodes they remained firmly attached to Europa or Africa from which they broke away. As Europe-Africa plate convergence slowed down well below 1 cm/yr at around 30 Ma ago these pre-collisional processes driven by plate convergence on a global scale gave way to more local processes of combined roll-back and crustal delamination in the Pannonian basin of the Carpathian embayment and in the Aegean (as well as in the Western Mediterranean, not discussed in this contribution). In the case of the Carpathian embayment E-directed roll back totally unrelated to Europe-Africa N-S-directed convergence, started at around 20 Ma ago, due to the presence relict oceanic lithosphere in the future Pannonian basin that remained un-subducted during collision. Due to total delamination of the crust from the eastward rolling back European mantle lithosphere the anticlockwise rotating ALCAPA crustal block, consisting of Eastern Alps and Western Carpathian

  5. Long Wavelength Fluorescence Ratiometric Zinc Biosensor

    PubMed Central

    Zeng, Hui Hui; Matveeva, Evgenia; Stoddard, Andrea K.; Fierke, Carol A.; Thompson, Richard B.

    2013-01-01

    A protein-based emission ratiometric fluorescence biosensor is described that exhibits sensitivity to free zinc ion solutions down to picomolar concentrations. Ratiometric measurements are widely used to assure accurate quantitation, and emission ratios are preferred for laser scanning microscopes such as confocal fluorescence microscopes. The relatively long emission wavelengths used are well suited to studies in tissues and other matrices which exhibit significant fluorescence background, and the apo-carbonic anhydrase moiety recognizes zinc ion with high and controllable specificity. PMID:23345045

  6. Biosensors Related LLT: Physiopathology, Background and Rationale

    NASA Astrophysics Data System (ADS)

    Palmieri, Beniamino; Capone, Stefania

    2011-08-01

    The Authors describe a new biosensor-related approach to LLT delivery, tailored to homogeneously integrate the external energy to the maximum patient compliance and receptivity; this project is based on the work hypothesis, by a pilot clinical trial and experimental animals (liver crush injury in the rat) confirmed that the diodes number, frequency, intensity, and pulses when synchronized with the vital parameters induce maximal physiological response in terms of regeneration and recovery.

  7. Dual-mode acoustic wave biosensors microarrays

    NASA Astrophysics Data System (ADS)

    Auner, Gregory W.; Shreve, Gina; Ying, Hao; Newaz, Golam; Hughes, Chantelle; Xu, Jianzeng

    2003-04-01

    We have develop highly sensitive and selective acoustic wave biosensor arrays with signal analysis systems to provide a fingerprint for the real-time identification and quantification of a wide array of bacterial pathogens and environmental health hazards. We have developed an unique highly sensitive dual mode acoustic wave platform prototype that, when combined with phage based selective detection elements, form a durable bacteria sensor. Arrays of these new real-time biosensors are integrated to form a biosensor array on a chip. This research and development program optimizes advanced piezoelectric aluminum nitride wide bandgap semiconductors, novel micromachining processes, advanced device structures, selective phage displays development and immobilization techniques, and system integration and signal analysis technology to develop the biosensor arrays. The dual sensor platform can be programmed to sense in a gas, vapor or liquid environment by switching between acoustic wave resonate modes. Such a dual mode sensor has tremendous implications for applications involving monitoring of pathogenic microorganisms in the clinical setting due to their ability to detect airborne pathogens. This provides a number of applications including hospital settings such as intensive care or other in-patient wards for the reduction of nosocomial infections and maintenance of sterile environments in surgical suites. Monitoring for airborn pathogen transmission in public transportation areas such as airplanes may be useful for implementation of strategies for redution of airborn transmission routes. The ability to use the same sensor in the liquid sensing mode is important for tracing the source of airborn pathogens to local liquid sources. Sensing of pathogens in saliva will be useful for sensing oral pathogens and support of decision-making strategies regarding prevention of transmission and support of treatment strategies.

  8. Integrated-optical directional coupler biosensor

    NASA Astrophysics Data System (ADS)

    Luff, B. J.; Harris, R. D.; Wilkinson, J. S.; Wilson, R.; Schiffrin, D. J.

    1996-04-01

    We present measurements of biomolecular binding reactions, using a new type of integrated-optical biosensor based on a planar directional coupler structure. The device is fabricated by Ag+ - Na+ ion exchange in glass, and definition of the sensing region is achieved by use of transparent fluoropolymer isolation layers formed by thermal evaporation. The suitability of the sensor for application to the detection of environmental pollutants is considered.

  9. Biosensor discovery of thyroxine transport disrupting chemicals

    SciTech Connect

    Marchesini, Gerardo R. Meimaridou, Anastasia; Haasnoot, Willem; Meulenberg, Eline; Albertus, Faywell; Mizuguchi, Mineyuki; Takeuchi, Makoto; Irth, Hubertus; Murk, Albertinka J.

    2008-10-01

    Ubiquitous chemicals may interfere with the thyroid system that is essential in the development and physiology of vertebrates. We applied a surface plasmon resonance (SPR) biosensor-based screening method for the fast screening of chemicals with thyroxine (T4) transport disrupting activity. Two inhibition assays using the main thyroid hormone transport proteins, T4 binding globulin (TBG) and transthyretin (TTR), in combination with a T4-coated biosensor chip were optimized and automated for screening chemical libraries. The transport protein-based biosensor assays were rapid, high throughput and bioeffect-related. A library of 62 chemicals including the natural hormones, polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and metabolites, halogenated bisphenol A (BPA), halogenated phenols, pharmaceuticals, pesticides and other potential environmentally relevant chemicals was tested with the two assays. We discovered ten new active compounds with moderate to high affinity for TBG with the TBG assay. Strikingly, the most potent binding was observed with hydroxylated metabolites of the brominated diphenyl ethers (BDEs) BDE 47, BDE 49 and BDE 99, that are commonly found in human plasma. The TTR assay confirmed the activity of previously identified hydroxylated metabolites of PCBs and PBDEs, halogenated BPA and genistein. These results show that the hydroxylated metabolites of the ubiquitous PBDEs not only target the T4 transport at the TTR level, but also, and to a great extent, at the TBG level where most of the T4 in humans is circulating. The optimized SPR biosensor-based transport protein assay is a suitable method for high throughput screening of large libraries for potential thyroid hormone disrupting compounds.

  10. Raman Spectroscopy Cell-based Biosensors

    PubMed Central

    Notingher, Ioan

    2007-01-01

    One of the main challenges faced by biodetection systems is the ability to detect and identify a large range of toxins at low concentrations and in short times. Cell-based biosensors rely on detecting changes in cell behaviour, metabolism, or induction of cell death following exposure of live cells to toxic agents. Raman spectroscopy is a powerful technique for studying cellular biochemistry. Different toxic chemicals have different effects on living cells and induce different time-dependent biochemical changes related to cell death mechanisms. Cellular changes start with membrane receptor signalling leading to cytoplasmic shrinkage and nuclear fragmentation. The potential advantage of Raman spectroscopy cell-based systems is that they are not engineered to respond specifically to a single toxic agent but are free to react to many biologically active compounds. Raman spectroscopy biosensors can also provide additional information from the time-dependent changes of cellular biochemistry. Since no cell labelling or staining is required, the specific time dependent biochemical changes in the living cells can be used for the identification and quantification of the toxic agents. Thus, detection of biochemical changes of cells by Raman spectroscopy could overcome the limitations of other biosensor techniques, with respect to detection and discrimination of a large range of toxic agents. Further developments of this technique may also include integration of cellular microarrays for high throughput in vitro toxicological testing of pharmaceuticals and in situ monitoring of the growth of engineered tissues.

  11. Hybrid nano plasmonics for integrated biosensor

    NASA Astrophysics Data System (ADS)

    Lin, Chii-Wann; Lee, Jun-Haw; Chiu, Nan-Fu; Lee, Szu-Yuan; Liu, Kou-Chen; Tsai, Feng-Yu; Yen, Chia-Yu; Lee, Chun-Nan

    2009-11-01

    SPR biosensor with OLED and nano-grating for HBV LAMP product detection is reported. Directional emissions by grating-coupler match the resonant condition of SP modes. Concentration changes result in color shift at specific angle. Real time detection of virus load down to 5 copies/25 ul can be achieved in 30 minutes. Surface plasmon Resonant (SPR) biosensor has been used for quantitative measurement of molecular interactions for its advantages of high sensitivity, label-free and real-time detection. In this paper, we report recent efforts on further enhancement of SPR biosensors by the heterogeneous integration of organic electroluminescence light source and nano-grating structure for the feasibility study on the fast and high sensitivity detection of HBV isothermal amplification products, Mg2P2O7. We demonstrated the surface plasmon coupled through hybrid nano-grating structure has highly directional emissions corresponding to the resonant condition of surface plasmon modes on the Au/air interface and controllable plasmonics band-gap by pitch modulation. SPGCE resulted in color change from yellowish green to orange at a certain viewing angle, when contacting glucose with concentration increasing from 10 to 40%.

  12. Design of nanostructured-based glucose biosensors

    NASA Astrophysics Data System (ADS)

    Komirisetty, Archana; Williams, Frances; Pradhan, Aswini; Konda, Rajini B.; Dondapati, Hareesh; Samantaray, Diptirani

    2012-04-01

    This paper presents the design of glucose sensors that will be integrated with advanced nano-materials, bio-coatings and electronics to create novel devices that are highly sensitive, inexpensive, accurate, and reliable. In the work presented, a glucose biosensor and its fabrication process flow have been designed. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. Currently, the biosensors are being fabricated using the process flow developed. Once completed, the sensors will be bio-functionalized and tested to characterize their performance, including their sensitivity and stability.

  13. Integrating and amplifying signal from riboswitch biosensors.

    PubMed

    Goodson, Michael S; Harbaugh, Svetlana V; Chushak, Yaroslav G; Kelley-Loughnane, Nancy

    2015-01-01

    Biosensors offer a built-in energy supply and inherent sensing machinery that when exploited correctly may surpass traditional sensors. However, biosensor systems have been hindered by a narrow range of ligand detection capabilities, a relatively low signal output, and their inability to integrate multiple signals. Integration of signals could increase the specificity of the sensor and enable detection of a combination of ligands that may indicate environmental or developmental processes when detected together. Amplifying biosensor signal output will increase detector sensitivity and detection range. Riboswitches offer the potential to widen the diversity of ligands that may be detected, and advances in synthetic biology are illuminating myriad possibilities in signal processing using an orthogonal parts-based engineering approach. In this chapter, we describe the design, building, and testing of a riboswitch-based Boolean logic AND gate in bacteria, where an output requires the activation of two riboswitches, and the biological circuitry required to amplify the output of the AND gate using natural extracellular bacterial communication signals to "wire" cells together. PMID:25605381

  14. Cultured neuronal networks as environmental biosensors.

    PubMed

    O'Shaughnessy, Thomas J; Gray, Samuel A; Pancrazio, Joseph J

    2004-01-01

    Contamination of water by toxins, either intentionally or unintentionally, is a growing concern for both military and civilian agencies and thus there is a need for systems capable of monitoring a wide range of natural and industrial toxicants. The EILATox-Oregon Workshop held in September 2002 provided an opportunity to test the capabilities of a prototype neuronal network-based biosensor with unknown contaminants in water samples. The biosensor is a portable device capable of recording the action potential activity from a network of mammalian neurons grown on glass microelectrode arrays. Changes in the action potential fi ring rate across the network are monitored to determine exposure to toxicants. A series of three neuronal networks derived from mice was used to test seven unknown samples. Two of these unknowns later were revealed to be blanks, to which the neuronal networks did not respond. Of the five remaining unknowns, a significant change in network activity was detected for four of the compounds at concentrations below a lethal level for humans: mercuric chloride, sodium arsenite, phosdrin and chlordimeform. These compounds--two heavy metals, an organophosphate and an insecticide--demonstrate the breadth of detection possible with neuronal networks. The results generated at the workshop show the promise of the neuronal network biosensor as an environmental detector but there is still considerable effort needed to produce a device suitable for routine environmental threat monitoring. PMID:15478174

  15. Sensitive-cell-based fish chromatophore biosensor

    NASA Astrophysics Data System (ADS)

    Plant, Thomas K.; Chaplen, Frank W.; Jovanovic, Goran; Kolodziej, Wojtek; Trempy, Janine E.; Willard, Corwin; Liburdy, James A.; Pence, Deborah V.; Paul, Brian K.

    2004-07-01

    A sensitive biosensor (cytosensor) has been developed based on color changes in the toxin-sensitive colored living cells of fish. These chromatophores are highly sensitive to the presence of many known and unknown toxins produced by microbial pathogens and undergo visible color changes in a dose-dependent manner. The chromatophores are immobilized and maintained in a viable state while potential pathogens multiply and fish cell-microbe interactions are monitored. Low power LED lighting is used to illuminate the chromatophores which are magnified using standard optical lenses and imaged onto a CCD array. Reaction to toxins is detected by observing changes is the total area of color in the cells. These fish chromatophores are quite sensitive to cholera toxin, Staphococcus alpha toxin, and Bordatella pertussis toxin. Numerous other toxic chemical and biological agents besides bacterial toxins also cause readily detectable color effects in chromatophores. The ability of the chromatophore cell-based biosensor to distinguish between different bacterial pathogens was examined. Toxin producing strains of Salmonella enteritis, Vibrio parahaemolyticus, and Bacillus cereus induced movement of pigmented organelles in the chromatophore cells and this movement was measured by changes in the optical density over time. Each bacterial pathogen elicited this measurable response in a distinctive and signature fashion. These results suggest a chromatophore cell-based biosensor assay may be applicable for the detection and identification of virulence activities associated with certain air-, food-, and water-borne bacterial pathogens.

  16. Biosensor for underwater chemical sensing (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Kusterbeck, Anne W.; Deschamps, Jeffrey R.; Charles, Paul T.

    2005-05-01

    Emerging biosensor approaches may prove useful in reducing false positives and improving detection probabilities for unexploded ordnance (UXO) and underwater explosives. NRL researchers previously developed a biosensor that was field-tested and validated for use in environmental remediation to detect explosives in groundwater. The sensor relies on the selective recognition by antibodies of target analytes, including the common explosives TNT and RDX. Laboratory work has demonstrated that sensors based on these displacement immunoassay formats can detect explosives at the part-per-trillion level in seawater. More recently, participating in an Office of Naval Research program on Chemical Sensing in the Marine Environment (CSME), tests were conducted in controlled underwater experiments at San Clemente, CA and Duck, NC. Simulated UXO targets, autonomous underwater vehicles (AUV) and multiple sensor approaches were used to demonstrate the feasibility of underwater chemical sensing. Efforts are now underway to integrate the biosensor into an underwater platform as part of a broader sensor system. We will describe results of these studies and outline possible operational scenarios for applications in harbor security.

  17. Biosensor UUV payload for underwater detection

    NASA Astrophysics Data System (ADS)

    Kusterbeck, Anne W.; Charles, Paul T.; Melde, Brian J.; Trammell, Scott A.; Adams, André A.; Deschamps, Jeffrey R.

    2010-04-01

    Increased emphasis on maritime domain awareness and port security has led to the development of unmanned underwater vehicles (UUVs) capable of extended missions. These systems rely most frequently on well-developed side scan sonar and acoustic methods to locate potential targets. The Naval Research Laboratory (NRL) is developing biosensors for underwater explosives detection that complement acoustic sensors and can be used as UUV payloads to monitor areas for port and harbor security or in detection of underwater unexploded ordnance (UXO) and biochemical threats. The prototype sensor has recently been demonstrated to detect explosives in seawater at trace levels when run in a continuous sampling mode. To overcome ongoing issues with sample preparation and facilitate rapid detection at trace levels in a marine environment, we have been developing new mesoporous materials for in-line preconcentration of explosives and other small molecules, engineering microfluidic components to improve the signal, and testing alternative signal transduction methods. Additional work is being done to optimize the optical components and sensor response time. Highlights of these current studies and our ongoing efforts to integrate the biosensor with existing detection technologies to reduce false positives are described. In addition, we present the results of field tests that demonstrate the prototype biosensor performance as a UUV payload.

  18. Biosensing using smectic and cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Popov, Piotr; Mann, Elizabeth; Jakli, Antal

    2015-03-01

    Liquid-crystal-based biosensors utilize liquid crystal alignment's high sensitivity to the presence of lipids and proteins self-assembled at the liquid crystal/aqueous solution interface. The optical response of the bulk liquid crystal to the interface offers inexpensive, easy optical detection of such biologically relevant molecules. Present technique uses nematic liquid crystal phase state that typically has a planar-to-homeotropic response only. Here we show that smectic and cholesteric phase states of liquid crystals can be used as new sensing modes that can provide additional information or improve the characteristics of a potential biosensor device. Smectic-A phase extends the detection range both toward the lower and higher concentration. Cholesteric phase (nematic with a chiral dopant) may be sensitive to the chirality of biological surface-active molecules such as phospholipids. Additionally, the ``finger-print'' texture of a cholesteric phase may show the differences between biomolecule homologues, thus providing a promising way of distinguishing between subtle differences of hydrocarbon chain or head-group size and structure.

  19. Manipulation of Magnetic Particles for Use in Photonic Biosensor Arrays

    NASA Astrophysics Data System (ADS)

    Siebe, Craig

    Trapping magnetic nanoparticles in wells in a photonic crystal biosensor array using magnetophoresis is desirable because it would allow for covalent bonding of antibodies onto the particles which would lead to an increase in sensitivity of the sensor. It was hypothesized that this could be achieved by engineering a magnetic field at each well by placing a, "magnetic tip," under each well and exposing the array to a uniform magnetic field which would create a magnetic gradient at each well in order to trap magnetic particles. A computational COMSOL model was created to determine the ideal shapes for the magnetic tips, but fabrication factors and the COMSOL model led to the tips being the same shape as the wells. Dip coating, centrifuging, and electrophoresis of iron oxide particles were tried as methods to fabricate magnetic tips. Electroplating the particles was determined to be the best method. Microscale arrays were fabricated and tested with micron scale beads in 3 different well sizes. Then smaller grooves were created by drop casting PMMA groves using PDMS imprints of CDs. Electron beam lithography and stamping into spin coated PMMA were also tried briefly. Trapping of 350 nm magnetic beads was attempted but was unsuccessful. Probably this occurred because the gradient produced by the magnetic tips was not strong enough to overcome the hydrodynamic forces of water that was swept over the array with Couette flows to clean the surface.

  20. Design and microfabrication of a lateral excited gallium arsenide biosensor

    NASA Astrophysics Data System (ADS)

    Bienaime, A.; Liu, L.; Elie-Caille, C.; Leblois, T.

    2012-02-01

    GaAs crystal presents some interesting perspectives for resonant biosensors due to its piezoelectric and good mechanical properties and the opportunity to bio-functionalize the surface. Moreover, GaAs can be micromachined by wet etching in several solutions, which constitutes a batch and low-cost process of fabrication. The lateral field excitation (LFE) is used to generate bulk acoustic waves. The main advantage of LFE is the possibility to measure in liquid media, moreover reduced aging and increased frequency stability are also ensured. In this study, an analytical modelization is used to determine the orientations of the vibrating membrane and the electric field that give satisfactory metrological performances. Electrical performances are discussed as a function of geometrical parameters. A simulation based on a Finite Element Modelization is performed in order to optimize the design of the resonant structure. The microfabrication process of the structure is presented. The choice of etchants is discussed in terms of etching rates and surface textures. Several steps of the fabrication of the sensing area structure are shown and characterized. Finally, the active area is fabricated according to the theoretical and experimental results of this study.

  1. Multivalent interaction based carbohydrate biosensors for signal amplification

    PubMed Central

    Wang, Yanyan; Chalagalla, Srinivas; Li, Tiehai; Sun, Xue-long; Zhao, Wei; Wang, Peng; Zeng, Xiangqun

    2010-01-01

    Multivalent interaction between boronic acids immobilized on Quartz Crystal Microbalance (QCM) sensor surface and the carbohydrates modified Au - nanoparticle (AuNP) has been demonstrated for the development of a sensitive carbohydrate biosensor. Briefly, a boronic acid - containing polymer (boropolymer) as multivalent carbohydrate receptor was oriented immobilized on the cysteamine coated electrode through isourea bond formation. Carbohydrates were conjugated to AuNPs to generate a multivalent carbohydrates moiety to amplify the response signal. Thus, the binding of the carbohydrate conjugated AuNPs to the boropolymer surface are multivalent which could simultaneously increase the binding affinity and specificity. We systematically studied the binding between five carbohydrate conjugated AuNPs and the boropolymer. Our studies show that the associate constant (Ka) was in the order of fucose < glucose < mannose < galactose < maltose. A linear response in the range from 23 µM to 3.83 mM was observed for mannose conjugated AuNPs and the boropolymer recognition elements, with the lower detection limit of 1.5 µM for the carbohydrate analytes. Furthermore, the multivalent binding between carbohydrates and boronic acids are reversible and allow the regeneration of boropolymer surface by using 1M acetic acid so as to sequentially capture and release the carbohydrate analytes. PMID:20863680

  2. A Microplate-Based System as In Vitro Model of Biofilm Growth and Quantification.

    PubMed

    Vandecandelaere, Ilse; Van Acker, Heleen; Coenye, Tom

    2016-01-01

    We describe a 96-well microtiter plate-based system as an in vitro model for biofilm formation and quantification. Although in vitro assays are artificial systems and thus significantly differ from in vivo conditions, they represent an important tool to evaluate biofilm formation and the effect of compounds on biofilms. Stainings to evaluate the amount of biomass (crystal violet staining) and the number of metabolically active cells (resazurin assay) are discussed and specific attention is paid to the use of this model to quantify persisters in sessile populations. PMID:26468099

  3. In vitro evaluation of fluorescence glucose biosensor response.

    PubMed

    Aloraefy, Mamdouh; Pfefer, T Joshua; Ramella-Roman, Jessica C; Sapsford, Kim E

    2014-01-01

    Rapid, accurate, and minimally-invasive glucose biosensors based on Förster Resonance Energy Transfer (FRET) for glucose measurement have the potential to enhance diabetes control. However, a standard set of in vitro approaches for evaluating optical glucose biosensor response under controlled conditions would facilitate technological innovation and clinical translation. Towards this end, we have identified key characteristics and response test methods, fabricated FRET-based glucose biosensors, and characterized biosensor performance using these test methods. The biosensors were based on competitive binding between dextran and glucose to concanavalin A and incorporated long-wavelength fluorescence dye pairs. Testing characteristics included spectral response, linearity, sensitivity, limit of detection, kinetic response, reversibility, stability, precision, and accuracy. The biosensor demonstrated a fluorescence change of 45% in the presence of 400 mg/dL glucose, a mean absolute relative difference of less than 11%, a limit of detection of 25 mg/dL, a response time of 15 min, and a decay in fluorescence intensity of 72% over 30 days. The battery of tests presented here for objective, quantitative in vitro evaluation of FRET glucose biosensors performance have the potential to form the basis of future consensus standards. By implementing these test methods for a long-visible-wavelength biosensor, we were able to demonstrate strengths and weaknesses with a new level of thoroughness and rigor. PMID:25006996

  4. A versatile biosensor device for continuous biomedical monitoring.

    PubMed

    Rhemrev-Boom, M M; Korf, J; Venema, K; Urban, G; Vadgama, P

    2001-12-01

    Although biosensors are by means suitable for continuous biomedical monitoring, due to fouling and blood clotting, in vivo performance is far from optimal. For this reason, ultrafiltration, microdialysis or open tubular flow is frequently used as interface. To secure quantitative recoveries of the analyte of interest, sampling at submicrolitre level will be necessary which in turn necessitates the development of small and versatile biosensor devices. Here, a miniaturised biosensor device, which directly can be connected to various interfaces will be presented. The biosensor device consists of a pulsefree pump and a biosensor with an internal volume of 10-20 nl. In this article, the production as well as the construction of the flow-through cell of the biosensor will be discussed. The advantages and disadvantages of several production processes will be demonstrated and a detailed protocol for the production of such a nanoliter flow-through cell will be presented. With respect to the bio-selector, several permselective membranes have been tested on their performance characteristics. Results obtained with these biosensors will be presented and discussed. Finally, a protocol based upon in situ electropolymerisation for the immobilisation of the biological component was defined and several biosensors based upon this principle have been produced and tested for the monitoring of glucose respectively lactate. To demonstrate, data obtained during a variety of in vivo studies at different clinical relevant applications will be presented. PMID:11679262

  5. Homemade Bienzymatic-Amperometric Biosensor for Beverages Analysis

    ERIC Educational Resources Information Center

    Blanco-Lopez, M. C.; Lobo-Castanon, M. J.; Miranda-Ordieres, A. J.

    2007-01-01

    The construction of an amperometric biosensor for glucose analysis is described demonstrating that the analysis is easy to perform and the biosensor gives good analytical performance. This experiment helped the students to acquire problem-solving and teamwork skills, allowing them to reach a high level of independent and critical thought.

  6. Multiple Pathogen Detection Using Biosensors: Advancements and Challenges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Advancements in biosensor research have considerably impacted clinical diagnostics for human health. Efforts in capitalizing on the sensitivity of biosensors for food pathogen detection are evident in the food safety/security research community. For practical application with foods that normally h...

  7. Recent Development of Nano-Materials Used in DNA Biosensors

    PubMed Central

    Xu, Kai; Huang, Junran; Ye, Zunzhong; Ying, Yibin; Li, Yanbin

    2009-01-01

    As knowledge of the structure and function of nucleic acid molecules has increased, sequence-specific DNA detection has gained increased importance. DNA biosensors based on nucleic acid hybridization have been actively developed because of their specificity, speed, portability, and low cost. Recently, there has been considerable interest in using nano-materials for DNA biosensors. Because of their high surface-to-volume ratios and excellent biological compatibilities, nano-materials could be used to increase the amount of DNA immobilization; moreover, DNA bound to nano-materials can maintain its biological activity. Alternatively, signal amplification by labeling a targeted analyte with nano-materials has also been reported for DNA biosensors in many papers. This review summarizes the applications of various nano-materials for DNA biosensors during past five years. We found that nano-materials of small sizes were advantageous as substrates for DNA attachment or as labels for signal amplification; and use of two or more types of nano-materials in the biosensors could improve their overall quality and to overcome the deficiencies of the individual nano-components. Most current DNA biosensors require the use of polymerase chain reaction (PCR) in their protocols. However, further development of nano-materials with smaller size and/or with improved biological and chemical properties would substantially enhance the accuracy, selectivity and sensitivity of DNA biosensors. Thus, DNA biosensors without PCR amplification may become a reality in the foreseeable future. PMID:22346713

  8. Design and simulation of ultrasensitive nano-biosensor based on OFPC

    NASA Astrophysics Data System (ADS)

    Nejadebrahimy, Mehdi; Halimi, Lida; Alipour-Banaei, Hamed

    2015-03-01

    We designed and simulated a nano-biosensor to work in wet chemical optical processes for the determination and analysis of gaseous or liquid media. For this purpose, the optical properties of materials have been studied, and by creating the relationship between the refractive index of materials and other optical parameters, the measurement process was carried out. In this work, an optical filter based on the photonic crystal (OFPC) was used. By creating an active environment for the interaction between the substance and electromagnetic light, a situation to measure the properties of available substances in that active environment could be provided. Considering that the defect created in the OFPC may cause disruption in its operation, so the volume of the environment should be limited. Creation of defects in the structure of the nano-biosensors can increase the accuracy and quality of measurements; finally by rearranging the created defects, the output will be placed in the appropriate scope. The accuracy is increased by applying the finite difference time domain (FDTD) modeling approach in order to analyze the wave equations governing the structure of the photonics crystal.

  9. Protein-protein binding detection with nanoparticle photonic crystal enhanced microscopy (NP-PCEM).

    PubMed

    Zhuo, Yue; Tian, Limei; Chen, Weili; Yu, Hojeong; Singamaneni, Srikanth; Cunningham, Brian T

    2014-01-01

    We demonstrate a novel microscopy-based biosensing approach that utilizes a photonic crystal (PC) surface to detect protein-protein binding with the functionalized nanoparticles as tags. This imaging approach utilizes the measurement of localized shifts in the resonant wavelength and resonant reflection magnitude from the PC biosensor in the presence of individual nanoparticles. Moreover, it substantially increases the sensitivity of the imaging approach through tunable localized surface plasmon resonant frequency of the nanoparticle matching with the resonance of the PC biosensor. Experimental demonstrations of photonic crystal enhanced microscopy (PCEM) imaging with single nanoparticle resolution are supported by Finite-Difference Time-Domain (FDTD) computer simulations. The ability to detect the surface adsorption of individual nanoparticles as tags offers a route to single molecule biosensing with photonic crystal biosensor in the future. PMID:25570391

  10. Large Scale Bacterial Colony Screening of Diversified FRET Biosensors

    PubMed Central

    Litzlbauer, Julia; Schifferer, Martina; Ng, David; Fabritius, Arne; Thestrup, Thomas; Griesbeck, Oliver

    2015-01-01

    Biosensors based on Förster Resonance Energy Transfer (FRET) between fluorescent protein mutants have started to revolutionize physiology and biochemistry. However, many types of FRET biosensors show relatively small FRET changes, making measurements with these probes challenging when used under sub-optimal experimental conditions. Thus, a major effort in the field currently lies in designing new optimization strategies for these types of sensors. Here we describe procedures for optimizing FRET changes by large scale screening of mutant biosensor libraries in bacterial colonies. We describe optimization of biosensor expression, permeabilization of bacteria, software tools for analysis, and screening conditions. The procedures reported here may help in improving FRET changes in multiple suitable classes of biosensors. PMID:26061878

  11. Resonance phenomenon of the ATP motor as an ultrasensitive biosensor.

    PubMed

    Wang, Peirong; Zhang, Xiaoguang; Zhang, Xu; Wang, Xia; Li, Xueren; Yue, Jiachang

    2012-09-28

    We designed a rotary biosensor as a damping effector, with the rotation of the F(0)F(1)-ATPase driven by Adenosine Triphosphate (ATP) synthesis being indicated by the fluorescence intensity and a damping effect force being induced by the binding of an RNA molecule to its probe on the rotary biosensor. We found that the damping effect could contribute to the resonance phenomenon and energy transfer process of our rotary biosensor in the liquid phase. This result indicates that the ability of the rotary motor to operate in the vibration harmonic mode depends on the environmental conditions and mechanism in that a few molecules of the rotary biosensor could induce all of the sensor molecules to fluoresce together. These findings contribute to the theory study of the ATPase motor and future development of biosensors for ultrasensitive detection. PMID:22960174

  12. Emerging Synergy between Nanotechnology and Implantable Biosensors: A Review

    PubMed Central

    Vaddiraju, Santhisagar; Tomazos, Ioannis; Burgess, Diane J; Jain, Faquir C; Papadimitrakopoulos, Fotios

    2010-01-01

    The development of implantable biosensors for continuous monitoring of metabolites is an area of sustained scientific and technological interest. On the other hand, nanotechnology, a discipline which deals with the properties of materials at the nanoscale, is developing as a potent tool to enhance the performance of these biosensors. This article reviews the current state of implantable biosensors, highlighting the synergy between nanotechnology and sensor performance. Emphasis is placed on the electrochemical method of detection in light of its widespread usage and substantial nanotechnology-based improvements in various aspects of electrochemical biosensor performance. Finally, issues regarding toxicity and biocompatibility of nanomaterials, along with future prospects for the application of nanotechnology in implantable biosensors, are discussed. PMID:20042326

  13. Electrochemical uranyl cation biosensor with DNA oligonucleotides as receptor layer.

    PubMed

    Jarczewska, Marta; Ziółkowski, Robert; Górski, Łukasz; Malinowska, Elżbieta

    2014-04-01

    The present study aims at the further development of the uranyl oligonucleotide-based voltammetric biosensor, which takes advantage of strong interaction between UO2(2+) and phosphate DNA backbone. Herein we report the optimization of working parameters of previously elaborated electrochemical DNA biosensor. It is shown that the sensor sensitivity is highly dependent on the oligonucleotide probe length and the incubation time of sensor in a sample solution. Consequently, the highest sensitivity was obtained for 10-nucleotide sequence and 60 min incubation time. The lower detection limit towards uranyl cation for developed biosensor was 30 nM. The influence of mixed monolayers and the possibility of developing a non-calibration device were also investigated. The selectivity of the proposed biosensor was significantly improved via elimination of adenine nucleobases from the DNA probe. Moreover, the regeneration procedure was elaborated and tested to prolong the use of the same biosensor for 4 subsequent determinations of UO2(2+). PMID:24334186

  14. Biosensor method and system based on feature vector extraction

    DOEpatents

    Greenbaum, Elias; Rodriguez, Jr., Miguel; Qi, Hairong; Wang, Xiaoling

    2013-07-02

    A system for biosensor-based detection of toxins includes providing at least one time-dependent control signal generated by a biosensor in a gas or liquid medium, and obtaining a time-dependent biosensor signal from the biosensor in the gas or liquid medium to be monitored or analyzed for the presence of one or more toxins selected from chemical, biological or radiological agents. The time-dependent biosensor signal is processed to obtain a plurality of feature vectors using at least one of amplitude statistics and a time-frequency analysis. At least one parameter relating to toxicity of the gas or liquid medium is then determined from the feature vectors based on reference to the control signal.

  15. Biosensor method and system based on feature vector extraction

    DOEpatents

    Greenbaum, Elias; Rodriguez, Jr., Miguel; Qi, Hairong; Wang, Xiaoling

    2012-04-17

    A method of biosensor-based detection of toxins comprises the steps of providing at least one time-dependent control signal generated by a biosensor in a gas or liquid medium, and obtaining a time-dependent biosensor signal from the biosensor in the gas or liquid medium to be monitored or analyzed for the presence of one or more toxins selected from chemical, biological or radiological agents. The time-dependent biosensor signal is processed to obtain a plurality of feature vectors using at least one of amplitude statistics and a time-frequency analysis. At least one parameter relating to toxicity of the gas or liquid medium is then determined from the feature vectors based on reference to the control signal.

  16. Review of Micro/Nanotechnologies for Microbial Biosensors

    PubMed Central

    Lim, Ji Won; Ha, Dogyeong; Lee, Jongwan; Lee, Sung Kuk; Kim, Taesung

    2015-01-01

    A microbial biosensor is an analytical device with a biologically integrated transducer that generates a measurable signal indicating the analyte concentration. This method is ideally suited for the analysis of extracellular chemicals and the environment, and for metabolic sensory regulation. Although microbial biosensors show promise for application in various detection fields, some limitations still remain such as poor selectivity, low sensitivity, and impractical portability. To overcome such limitations, microbial biosensors have been integrated with many recently developed micro/nanotechnologies and applied to a wide range of detection purposes. This review article discusses micro/nanotechnologies that have been integrated with microbial biosensors and summarizes recent advances and the applications achieved through such novel integration. Future perspectives on the combination of micro/nanotechnologies and microbial biosensors will be discussed, and the necessary developments and improvements will be strategically deliberated. PMID:26029689

  17. Current Trends in Nanomaterial-Based Amperometric Biosensors

    PubMed Central

    Hayat, Akhtar; Catanante, Gaëlle; Marty, Jean Louis

    2014-01-01

    The last decade has witnessed an intensive research effort in the field of electrochemical sensors, with a particular focus on the design of amperometric biosensors for diverse analytical applications. In this context, nanomaterial integration in the construction of amperometric biosensors may constitute one of the most exciting approaches. The attractive properties of nanomaterials have paved the way for the design of a wide variety of biosensors based on various electrochemical detection methods to enhance the analytical characteristics. However, most of these nanostructured materials are not explored in the design of amperometric biosensors. This review aims to provide insight into the diverse properties of nanomaterials that can be possibly explored in the construction of amperometric biosensors. PMID:25494347

  18. Antimicrobial susceptibility assays based on the quantification of bacterial lipopolysaccharides via a label free lectin biosensor.

    PubMed

    Ma, Fen; Rehman, Abdul; Sims, Matthew; Zeng, Xiangqun

    2015-04-21

    A label free lectin biosensor developed in our laboratory that can quantitatively measure the binding between the lectin immobilized at the carbohydrate sensor surface and the lipopolysaccharide (LPS) on Gram-negative bacteria was demonstrated for an antibiotic susceptibility assay. The biosensor utilizes a polythiophene interface containing fused quinone moieties glycosylated to form a carbohydrate platform for the immobilization of Concanavalin A (Con A) and is capable of LPS binding measurements via orthogonal quartz crystal microbalance and electrochemical readouts (EQCM). Such orthogonal transduction provides cross-validation, better sensor sensitivity, and a large dynamic range of the measurements. We have applied this label free lectin biosensor for a new antibiotic susceptibility assay by characterizing the antimicrobial activities of various antibiotics (i.e., ciprofloxacin, ceftriaxone, and tetracycline) against Escherichia coli W1485 as a model system. The label free biosensor allows both end point and real time measurements of antibiotic effects on the bacterial cell surface LPS, which is shown to correlate to their antibiotic effects. At the end point, after 18 h incubation of bacterial cells with these three antibiotics respectively, the bacterial LPS binding signal was reduced to 23%, 27%, and 38%, respectively, for the three antibiotics, indicating that ciprofloxacin is the most effective against this E. coli strain. Real time measurements at the 1 h time point showed a similar trend with a reduction of binding to 91%, 93%, and 95%, respectively. From the binding kinetics of these measurements, the relaxation time (τ) was obtained, where higher τ value means slow binding interactions between the lectin and the bacterial LPS. The obtained order of τ, (i.e., τciprofloxacin > τceftriaxone > τtetracycline) again indicated that ciprofloxacin has more bactericidal activity than the other two antibiotics with the same concentrations. Thus, we are

  19. Inter- and Intra-Assay Reproducibility of Microplate Alamar Blue Assay Results for Isoniazid, Rifampicin, Ethambutol, Streptomycin, Ciprofloxacin, and Capreomycin Drug Susceptibility Testing of Mycobacterium tuberculosis▿ †

    PubMed Central

    Leonard, Brian; Coronel, Jorge; Siedner, Mark; Grandjean, Louis; Caviedes, Luz; Navarro, Pilar; Gilman, Robert H.; Moore, David A. J.

    2008-01-01

    The intersample and intrasample variability of the results obtained with the microplate Alamar blue assay for the indirect drug susceptibility testing of Mycobacterium tuberculosis was investigated. Between 1.2 and 8.5% of paired MICs differed by more than one twofold dilution, resulting in discordant susceptible-resistant designations at frequencies between 0.6% (rifampin) and 18.9% (ethambutol). PMID:18701659

  20. High-density fiber optic biosensor arrays

    NASA Astrophysics Data System (ADS)

    Epstein, Jason R.; Walt, David R.

    2002-02-01

    Novel approaches are required to coordinate the immense amounts of information derived from diverse genomes. This concept has influenced the expanded role of high-throughput DNA detection and analysis in the biological sciences. A high-density fiber optic DNA biosensor was developed consisting of oligonucleotide-functionalized, 3.1 mm diameter microspheres deposited into the etched wells on the distal face of a 500 micrometers imaging fiber bundle. Imaging fiber bundles containing thousands of optical fibers, each associated with a unique oligonucleotide probe sequence, were the foundation for an optically connected, individually addressable DNA detection platform. Different oligonucleotide-functionalized microspheres were combined in a stock solution, and randomly dispersed into the etched wells. Microsphere positions were registered from optical dyes incorporated onto the microspheres. The distribution process provided an inherent redundancy that increases the signal-to-noise ratio as the square root of the number of sensors examined. The representative amount of each probe-type in the array was dependent on their initial stock solution concentration, and as other sequences of interest arise, new microsphere elements can be added to arrays without altering the existing detection capabilities. The oligonucleotide probe sequences hybridize to fluorescently-labeled, complementary DNA target solutions. Fiber optic DNA microarray research has included DNA-protein interaction profiles, microbial strain differentiation, non-labeled target interrogation with molecular beacons, and single cell-based assays. This biosensor array is proficient in DNA detection linked to specific disease states, single nucleotide polymorphism (SNP's) discrimination, and gene expression analysis. This array platform permits multiple detection formats, provides smaller feature sizes, and enables sensor design flexibility. High-density fiber optic microarray biosensors provide a fast

  1. Biosensors for functional food safety and analysis.

    PubMed

    Lavecchia, Teresa; Tibuzzi, Arianna; Giardi, Maria Teresa

    2010-01-01

    The importance of safety and functionality analysis of foodstuffs and raw materials is supported by national legislations and European Union (EU) directives concerning not only the amount of residues of pollutants and pathogens but also the activity and content of food additives and the health claims stated on their labels. In addition, consumers' awareness of the impact of functional foods' on their well-being and their desire for daily healthcare without the intake pharmaceuticals has immensely in recent years. Within this picture, the availability of fast, reliable, low cost control systems to measure the content and the quality of food additives and nutrients with health claims becomes mandatory, to be used by producers, consumers and the governmental bodies in charge of the legal supervision of such matters. This review aims at describing the most important methods and tools used for food analysis, starting with the classical methods (e.g., gas-chromatography GC, high performance liquid chromatography HPLC) and moving to the use of biosensors-novel biological material-based equipments. Four types of bio-sensors, among others, the novel photosynthetic proteins-based devices which are more promising and common in food analysis applications, are reviewed. A particular highlight on biosensors for the emerging market of functional foods is given and the most widely applied functional components are reviewed with a comprehensive analysis of papers published in the last three years; this report discusses recent trends for sensitive, fast, repeatable and cheap measurements, focused on the detection of vitamins, folate (folic acid), zinc (Zn), iron (Fe), calcium (Ca), fatty acids (in particular Omega 3), phytosterols and phytochemicals. A final market overview emphasizes some practical aspects ofbiosensor applications. PMID:21520718

  2. Infrared biosensors based on graphene plasmonics: modeling.

    PubMed

    Zhao, Yuan; Hu, Xiang; Chen, Guanxiong; Zhang, Xuanru; Tan, Ziqi; Chen, Junhua; Ruoff, Rodney S; Zhu, Yanwu; Lu, Yalin

    2013-10-28

    We propose a biosensor by exploiting localized plasmons in graphene and biomolecule adsorption on it. Numerical simulations demonstrate that the sensitivity of such a device can achieve a high value of up to 1697 nm/RIU (refractive index unit) when the wavelength shift at the plasmon resonance is detected. The transparent substrate supporting graphene can be chosen potentially from a wide range of materials including insulators, semiconductors, polymers, and gels. The plasmon resonance wavelength can be tuned with electrostatic doping and/or structure modulation of graphene. Furthermore, the device works in a wide angle range of incident light since the transverse magnetic (TM) polarization is independent of incident angles. PMID:24005890

  3. More About Thin-Membrane Biosensor

    NASA Technical Reports Server (NTRS)

    Case, George D.; Worley, Jennings F., III

    1994-01-01

    Report presents additional information about device described in "Thin-Membrane Sensor With Biochemical Switch" (MFS-26121). Device is modular sensor that puts out electrical signal indicative of chemical or biological agent. Signal produced as membrane-crossing ion current triggered by chemical reaction between agent and recognition protein conjugated to channel blocker. Prototype of biosensor useful in numerous laboratory, industrial, or field applications; such as to detect bacterial toxins in food, to screen for disease-producing micro-organisms, or to warn of toxins or pollutants in air.

  4. Aptamer-modified nanoparticles as biosensors.

    PubMed

    Lönne, Maren; Zhu, Guohong; Stahl, Frank; Walter, Johanna-Gabriela

    2014-01-01

    Aptamers are short oligonucleotides that are capable of selectively binding to their corresponding target. Therefore, they can be thought of as a nucleic acid-based alternative to antibodies and can substitute for their amino acid-based counterparts in analytical applications, including as receptors in biosensors. Here they offer several advantages because their nucleic acid nature and their binding via an induced fit mechanism enable novel sensing strategies. In this article, the utilization of aptamers as novel bio-receptors in combination with nanoparticles as transducer elements is reviewed. In addition to these analytical applications, the medical relevance of aptamer-modified nanoparticles is described. PMID:23824145

  5. Biosensor systems for pesticide determination in water

    NASA Astrophysics Data System (ADS)

    Bilitewski, Ursula; Bier, Frank F.; Beyersdorf-Radeck, Baerbel; Rueger, Petra; Zischkale, Frank; Schmid, Rolf D.

    1993-03-01

    Different biosensor systems suitable for the determination of pesticides in water are described. They are based on immobilized biological components, which are sensitive to compounds commonly used as pesticides. The biological components in the work described here were microorganisms capable of degrading chlorinated aromatic compounds, cholinesterases which are inhibited by carbamates and organophosphates, and antibodies specific to triazines. They were immobilized on various carriers and were either integrated in automated flow-through systems or developed as disposable electrodes. In this contribution, characteristics features of the different formats are given, e.g., the dependence of the specificity and sensitivity of the system on the biological component.

  6. A combination turbidity and supernatant microplate assay to rank-order the supersaturation limits of early drug candidates.

    PubMed

    Morrison, John S; Nophsker, Michelle J; Haskell, Roy J

    2014-10-01

    A unique opportunity exists at the drug discovery stage to overcome inherently poor solubility by selecting drug candidates with superior supersaturation propensity. Existing supersaturation assays compare either precipitation-resistant or precipitation-inhibiting excipients, or higher-energy polymorphic forms, but not multiple compounds or multiple concentrations. Furthermore, these assays lack sufficient throughput and compound conservation necessary for implementation in the discovery environment. A microplate-based combination turbidity and supernatant concentration assay was therefore developed to determine the extent to which different compounds remain in solution as a function of applied concentration in biorelevant media over a specific period of time. Dimethyl sulfoxide stock solutions at multiple concentrations of four poorly soluble, weak base compounds (Dipyridamole, Ketoconazole, Albendazole, and Cinnarizine) were diluted with pH 6.5 buffer as well as FaSSIF. All samples were monitored for precipitation by turbidity at 600 nm over 1 h and the final supernatant concentrations were measured. The maximum supersaturation ratio was calculated from the supersaturation limit and the equilibrium solubility in each media. Compounds were rank-ordered by supersaturation ratio: Ketoconazole > Dipyridamole > Cinnarizine ∼ Albendazole. These in vitro results correlated well with oral AUC ratios from published in vivo pH effect studies, thereby confirming the validity of this approach. PMID:25070886

  7. Rapid, low-technology MIC determination with clinical Mycobacterium tuberculosis isolates by using the microplate Alamar Blue assay.

    PubMed

    Franzblau, S G; Witzig, R S; McLaughlin, J C; Torres, P; Madico, G; Hernandez, A; Degnan, M T; Cook, M B; Quenzer, V K; Ferguson, R M; Gilman, R H

    1998-02-01

    A colorimetric, microplate-based Alamar Blue assay (MABA) method was used to determine the MICs of isoniazid (INH), rifampin, streptomycin (SM), and ethambutol (EMB) for 34 Peruvian Mycobacterium tuberculosis isolates (including both pansensitive and multidrug-resistant strains) and the H37Rv strain by using bacterial suspensions prepared directly from solid media. Results for all isolates were available within 8 days. Discordant results were observed on initial tests for 3 of 16 INH-susceptible isolates, 5 of 31 EMB-susceptible isolates, and 2 of 4 SM-resistant isolates (by the BACTEC 460 system). The overall agreements between the MICs obtained by MABA and the results obtained with the BACTEC 460 system were 87.9% for initial results and 93.6% after retesting 12 of 17 samples with discrepant results. Interpretation of MABA endpoints improved with technical experience. The MABA is a simple, rapid, low-cost, appropriate technology which does not require expensive instrumentation and which makes use of a nontoxic, temperature-stable reagent. PMID:9466742

  8. Rapid, Low-Technology MIC Determination with Clinical Mycobacterium tuberculosis Isolates by Using the Microplate Alamar Blue Assay

    PubMed Central

    Franzblau, Scott G.; Witzig, Richard S.; McLaughlin, James C.; Torres, Patricia; Madico, Guillermo; Hernandez, Antonio; Degnan, Michelle T.; Cook, Mary B.; Quenzer, Virginia K.; Ferguson, Robert M.; Gilman, Robert H.

    1998-01-01

    A colorimetric, microplate-based Alamar Blue assay (MABA) method was used to determine the MICs of isoniazid (INH), rifampin, streptomycin (SM), and ethambutol (EMB) for 34 Peruvian Mycobacterium tuberculosis isolates (including both pansensitive and multidrug-resistant strains) and the H37Rv strain by using bacterial suspensions prepared directly from solid media. Results for all isolates were available within 8 days. Discordant results were observed on initial tests for 3 of 16 INH-susceptible isolates, 5 of 31 EMB-susceptible isolates, and 2 of 4 SM-resistant isolates (by the BACTEC 460 system). The overall agreements between the MICs obtained by MABA and the results obtained with the BACTEC 460 system were 87.9% for initial results and 93.6% after retesting 12 of 17 samples with discrepant results. Interpretation of MABA endpoints improved with technical experience. The MABA is a simple, rapid, low-cost, appropriate technology which does not require expensive instrumentation and which makes use of a nontoxic, temperature-stable reagent. PMID:9466742

  9. Reduced turn-around time for Mycobacterium tuberculosis drug susceptibility testing with a proportional agar microplate assay.

    PubMed

    Nguyen, V A T; Nguyen, H Q; Vu, T T; Nguyen, N A T; Duong, C M; Tran, T H T; Nguyen, H V; Dang, D A; Bañuls, A-L

    2015-12-01

    Multidrug-resistant tuberculosis is a major issue worldwide; however, accessibility to drug susceptibility testing (DST) is still limited in developing countries, owing to high costs and complexity. We developed a proportion method on 12-well microplates for DST. The assay reduced the time to results to <12 days and <10 days when bacterial growth was checked with the naked eye or a microscope, respectively. Comparison with the Canetti-Grosset method showed that the results of the two assays almost overlapped (kappa index 0.98 (95% CI 0.91-1.00) for isoniazid, rifampicin, streptomycin; and kappa index 0.92 (95% CI 0.85-0.99) for ethambutol). The sequencing of genes involved in drug resistance showed similar level of phenotype-genotype agreement between techniques. Finally, measurement of the MICs of rifampicin and ethambutol suggests that the currently used critical ethambutol concentration should be revised, and that the current molecular drug susceptibility tests for rifampicin need to be re-evaluated, as in vitro rifampicin-sensitive isolates could harbour drug resistance-associated mutation(s). PMID:26348263

  10. A rapid and high-throughput microplate spectrophotometric method for field measurement of nitrate in seawater and freshwater

    PubMed Central

    Wu, Jiapeng; Hong, Yiguo; Guan, Fengjie; Wang, Yan; Tan, Yehui; Yue, Weizhong; Wu, Meilin; Bin, Liying; Wang, Jiaping; Wen, Jiali

    2016-01-01

    The well-known zinc-cadmium reduction method is frequently used for determination of nitrate. However, this method is seldom to be applied on field research of nitrate due to the long time consuming and large sample volume demand. Here, we reported a modified zinc-cadmium reduction method (MZCRM) for measurement of nitrate at natural-abundance level in both seawater and freshwater. The main improvements of MZCRM include using small volume disposable tubes for reaction, a vortex apparatus for shaking to increase reduction rate, and a microplate reader for high-throughput spectrophotometric measurements. Considering salt effect, two salinity sections (5~10 psu and 20~35 psu) were set up for more accurate determination of nitrate in low and high salinity condition respectively. Under optimized experimental conditions, the reduction rates were stabilized on 72% and 63% on the salinity of 5 and 20 psu respectively. The lowest detection limit for nitrate was 0.5 μM and was linear up to 100 μM (RSDs was 4.8%). Environmental samples assay demonstrated that MZCRM was well consistent with conventional zinc-cadmium reduction method. In total, this modified method improved accuracy and efficiency of operations greatly, and would be realized a rapid and high-throughput determination of nitrate in field analysis of nitrate with low cost. PMID:26832984

  11. A rapid and high-throughput microplate spectrophotometric method for field measurement of nitrate in seawater and freshwater

    NASA Astrophysics Data System (ADS)

    Wu, Jiapeng; Hong, Yiguo; Guan, Fengjie; Wang, Yan; Tan, Yehui; Yue, Weizhong; Wu, Meilin; Bin, Liying; Wang, Jiaping; Wen, Jiali

    2016-02-01

    The well-known zinc-cadmium reduction method is frequently used for determination of nitrate. However, this method is seldom to be applied on field research of nitrate due to the long time consuming and large sample volume demand. Here, we reported a modified zinc-cadmium reduction method (MZCRM) for measurement of nitrate at natural-abundance level in both seawater and freshwater. The main improvements of MZCRM include using small volume disposable tubes for reaction, a vortex apparatus for shaking to increase reduction rate, and a microplate reader for high-throughput spectrophotometric measurements. Considering salt effect, two salinity sections (5~10 psu and 20~35 psu) were set up for more accurate determination of nitrate in low and high salinity condition respectively. Under optimized experimental conditions, the reduction rates were stabilized on 72% and 63% on the salinity of 5 and 20 psu respectively. The lowest detection limit for nitrate was 0.5 μM and was linear up to 100 μM (RSDs was 4.8%). Environmental samples assay demonstrated that MZCRM was well consistent with conventional zinc-cadmium reduction method. In total, this modified method improved accuracy and efficiency of operations greatly, and would be realized a rapid and high-throughput determination of nitrate in field analysis of nitrate with low cost.

  12. Enhanced Microwave Absorption Properties of Flexible Polymer Composite Based on Hexagonal NiCo2O4 Microplates and PVDF

    NASA Astrophysics Data System (ADS)

    Luo, Hui; Wang, Xian; Song, Kai; Yang, Jing; Gong, Rongzhou

    2016-05-01

    Hexagonal NiCo2O4 microplates were synthesized via a facile one-pot hydrothermal method and followed by a subsequent annealing process. The complex permittivity and permeability of a NiCo2O4 and polyvinylidene fluoride (PVDF) composite were investigated over 2-18 GHz. The experiment indicated that the good microwave absorption performance of NiCo2O4@PVDF depends on dielectric loss and quarter-wavelength cancellation. Our results show that the absorption frequency bandwidth of reflection loss (RL) less than -20 dB for the NiCo2O4@PVDF composite can be measured over the frequency range of 3-15.5 GHz with an absorbing thickness that varies in the range of 1.25-5 mm. Furthermore, an optimal RL of -44.8 dB was observed at 10.7 GHz with a thickness of 1.75 mm. The loss mechanism is also discussed.

  13. Molecular characterization and expression profiles of olfactory receptor genes in the parasitic wasp, Microplitis mediator (Hymenoptera: Braconidae).

    PubMed

    Ma, Long; Gu, Shao-Hua; Liu, Ze-Wen; Wang, Shan-Ning; Guo, Yu-Yuan; Zhou, Jing-Jiang; Zhang, Yong-Jun

    2014-01-01

    Olfactory receptors (OR) are believed to fulfil an indispensable role in insects host-seeking, mating and ovipositing. We obtained 4785 high-quality expressed sequencing tags (EST) from the antennal cDNA library of the parasitic wasp Microplitis mediator, a natural enemy of crop pests. After assembling, 786 contigs and 2130 singletons were generated. Using BLAST searches, a number of olfactory-related genes were identified, including ESTs encoding for 25 ORs. 14 full-length OR genes were cloned and their expression profiles in the wasp olfactory organs were quantified by real-time qRT-PCR. The results indicated a diverse distribution between the tissues and genders, yet the majority of OR genes are highly expressed in antennae. Three OR genes (Or2, Or12 and Or13) are highly expressed in female antennae, eight OR genes (ORco, Or3, Or4, Or5, Or7, Or8, Or9 and Or11) are highly expressed in male antennae. This is the first report on tissue-specific expression of wasp OR genes. Our study provides a foundational knowledge to explore and understand the molecular basis of odorant reception in this parasitic wasp and for the study of trophic interactions of natural enemy. PMID:24291166

  14. Late Pleistocene and Holocene uplift history of Cyprus: implications for active tectonics along the southern margin of the Anatolian microplate

    USGS Publications Warehouse

    Harrison, R.W.; Tsiolakis, E.; Stone, B.D.; Lord, A.; McGeehin, J.P.; Mahan, S.A.; Chirico, P.

    2013-01-01

    The nature of the southern margin of the Anatolian microplate during the Neogene is complex, controversial and fundamental in understanding active plate-margin tectonics and natural hazards in the Eastern Mediterranean region. Our investigation provides new insights into the Late Pleistocene uplift history of Cyprus and the Troodos Ophiolite. We provide isotopic (14C) and radiogenic (luminescence) dates of outcropping marine sediments in eastern Cyprus that identify periods of deposition during marine isotope stages (MIS) 3, 4, 5 and 6. Past sea-levels indicated by these deposits are c. 95±25 m higher in elevation than estimates of worldwide eustatic sea-level. An uplift rate of c. 1.8 mm/year and possibly as much as c. 4.1 mm/year in the past c. 26–40 ka is indicated. Holocene marine deposits also occur at elevations higher than those expected for past SL and suggest uplift rates of c. 1.2–2.1 mm/year. MIS-3 marine deposits that crop out in southern and western Cyprus indicate uniform island-wide uplift. We propose a model of tectonic wedging at a plate-bounding restraining bend as a mechanism for Late Pleistocene to Holocene uplift of Cyprus; uplift is accommodated by deformation and seismicity along the margins of the Troodos Ophiolite and re-activation of its low-angle, basal shear zone.

  15. Enhanced Microwave Absorption Properties of Flexible Polymer Composite Based on Hexagonal NiCo2O4 Microplates and PVDF

    NASA Astrophysics Data System (ADS)

    Luo, Hui; Wang, Xian; Song, Kai; Yang, Jing; Gong, Rongzhou

    2016-08-01

    Hexagonal NiCo2O4 microplates were synthesized via a facile one-pot hydrothermal method and followed by a subsequent annealing process. The complex permittivity and permeability of a NiCo2O4 and polyvinylidene fluoride (PVDF) composite were investigated over 2-18 GHz. The experiment indicated that the good microwave absorption performance of NiCo2O4@PVDF depends on dielectric loss and quarter-wavelength cancellation. Our results show that the absorption frequency bandwidth of reflection loss (RL) less than -20 dB for the NiCo2O4@PVDF composite can be measured over the frequency range of 3-15.5 GHz with an absorbing thickness that varies in the range of 1.25-5 mm. Furthermore, an optimal RL of -44.8 dB was observed at 10.7 GHz with a thickness of 1.75 mm. The loss mechanism is also discussed.

  16. Development of a fluorimetric multispecies 96-well micro-plate growth test for screening metal toxicity to phytoplankton

    SciTech Connect

    Peterson, H.G.; Ruecker, N.J.; Cantin, I.A.; Nyholm, N.; Dal-Jensen, S.

    1995-12-31

    The rapid and cost-effective screening of industrial waste is an ideal approach to regulations that offer true protection of aquatic habitats. For these tests to be ecologically important protection of large groups of organisms is also essential. This can best be done by testing batteries of species. Photosynthetic organisms compose 99.9% of habitats as well as providing food for higher trophic levels. A test was developed that can accommodate the testing of most phytoplanktonic species irrespective of morphology (unicellular, multicellular, colonial, filamentous). Forty eight to 72 h growth tests were carried out with green algae, diatoms, and cyanobacteria. The algae were incubated with different levels of toxicants in 96-well microplates which were read in a 96-well fluorometric plate reader. Phytoplankton emitting low levels of fluorescence can be incubated with DCMU, which can increase the fluorescent signal 2 to 4 times. The data from the plate reader is transferred to a computer spreadsheet and inhibition levels are automatically calculated. Eleven metal mining wastes from across Canada were tested against this method using the following phytoplanktonic species: Selenastrum, Nannochloris (green algae), Nitzschia (diatom), Microcystis, and Pseudoanabaena (cyanobacteria). These wastes were also screened against Microtox. All wastes were highly toxic to the tested phytoplankton, but only 4 were toxic to Microtox{trademark}.

  17. Late Miocene to Recent formation of the Aure-Moresby fold-thrust belt and foreland basin as a consequence of Woodlark microplate rotation, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Ott, Bryan; Mann, Paul

    2015-06-01

    The Aure-Moresby fold-thrust belt and Aure-Moresby foreland basin are located in the eastern Gulf of Papua (GOP), Papua New Guinea (PNG), and formed during late Miocene-Recent as the result of large-scale, counterclockwise rotation of the 355,000 km2 Woodlark microplate. To document the structure, stratigraphy, and age of convergent deformation along the poorly studied, western edge of the rotating Woodlark microplate, we integrate results of 2,538 km of previously unpublished 2-D seismic reflection data with onshore geologic and GPS studies from previous workers. The late Miocene Aure-Moresby fold-thrust belt is a 400 km long, northwest-trending fold-belt exposed onshore in Papua New Guinea that plunges to the southeast, where continuous folds and northeast-dipping thrusts can be imaged in the subsurface for more than 250 km. The arcuate trend of the Aure-Moresby fold-thrust belt along the southwestern coast and offshore areas of the Papuan peninsula parallels the shape of the adjacent, offshore Aure-Moresby foreland basin and the strike of the transpressional segment of the left-lateral Owen-Stanley fault zone (OSFZ) passing along the center of the Papuan peninsula. As the OSFZ becomes more transtensional east of 148°E, folds of the Aure-Moresby fold-thrust belt along southern coast of the peninsula become less prominent, and the adjacent Aure-Moresby foreland basin transitions into an undeformed Cenozoic passive margin setting. These observations of convergent an left-lateral deformation along the Aure-Moresby fold-thrust belt are consistent with: (1) counterclockwise rotation of the Woodlark microplate known from regional GPS studies; (2) coeval opening of the Woodlark basin along its southern edge in the late Miocene; and (3) rapid subduction at the New Britain trench along its northern edge. The kinematics of the rotating Woodlark microplate are driven by slab pull forces acting on the actively subducting northern edge of the microplate.

  18. Did the Kyrenia Range of northern Cyprus rotate with the Troodos-Hatay microplate during the tectonic evolution of the eastern Mediterranean?

    NASA Astrophysics Data System (ADS)

    Morris, Antony; Robertson, Alastair H. F.; Anderson, Mark W.; Hodgson, Emma

    2016-01-01

    Previous palaeomagnetic studies have allowed the recognition of a distinctive area of Neotethyan oceanic rocks, including the Troodos ophiolite in Cyprus and the Hatay ophiolite to the east in southern Turkey, that underwent 90° of anticlockwise rotation between Late Cretaceous (Campanian) and Early Eocene time. The southern and western boundaries of this rotated Troodos-Hatay microplate have been inferred to lie within, or adjacent to, zones of deformed oceanic and continental margin rocks that are now exposed in southern and western Cyprus; however, the northern boundary of the microplate remains undefined. Relevant to this problem, palaeomagnetic data are presented here from basaltic lavas exposed along the Kyrenia Range, mostly from Late Cretaceous (Maastrichtian) sites and one Eocene site. A positive inclination-only fold test demonstrates that remanences are pre-deformational in age, and positive conglomerate tests show that magnetic remanences were acquired before Late Eocene-Early Oligocene time, together suggesting that primary magnetizations are preserved. Data from the eastern Kyrenia Range and the Karpas Peninsula (the easternmost extension of the Kyrenia Range) document significant relative tectonic rotation between these localities, with no rotation in the eastern range versus 30° of anticlockwise rotation of the Karpas Peninsula. Unfortunately, palaeomagnetic sites from the western Kyrenia Range did not yield tectonically interpretable magnetization directions, probably due to complex poly-phase thrusting and folding, and the central range also yielded no interpretable data. However, the available palaeomagnetic data are sufficient to demonstrate that the Kyrenia terrane underwent a separate rotation history to the Troodos-Hatay microplate and also implies that the northern boundary of the Troodos-Hatay microplate was located between the Troodos ophiolite and the Kyrenia Range. The former microplate margin has since been overridden and concealed by

  19. A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor

    PubMed Central

    Lee, Jieun; Jang, Jaeman; Choi, Bongsik; Yoon, Jinsu; Kim, Jee-Yeon; Choi, Yang-Kyu; Myong Kim, Dong; Hwan Kim, Dae; Choi, Sung-Jin

    2015-01-01

    This study demonstrates a hybrid biosensor comprised of a silicon nanowire (SiNW) integrated with an amplifier MOSFET to improve the current response of field-effect-transistor (FET)-based biosensors. The hybrid biosensor is fabricated using conventional CMOS technology, which has the potential advantage of high density and low noise performance. The biosensor shows a current response of 5.74 decades per pH for pH detection, which is 2.5 × 105 times larger than that of a single SiNW sensor. In addition, we demonstrate charged polymer detection using the biosensor, with a high current change of 4.5 × 105 with a 500 nM concentration of poly(allylamine hydrochloride). In addition, we demonstrate a wide dynamic range can be obtained by adjusting the liquid gate voltage. We expect that this biosensor will be advantageous and practical for biosensor applications which requires lower noise, high speed, and high density. PMID:26197105

  20. A Highly Responsive Silicon Nanowire/Amplifier MOSFET Hybrid Biosensor.

    PubMed

    Lee, Jieun; Jang, Jaeman; Choi, Bongsik; Yoon, Jinsu; Kim, Jee-Yeon; Choi, Yang-Kyu; Kim, Dong Myong; Kim, Dae Hwan; Choi, Sung-Jin

    2015-01-01

    This study demonstrates a hybrid biosensor comprised of a silicon nanowire (SiNW) integrated with an amplifier MOSFET to improve the current response of field-effect-transistor (FET)-based biosensors. The hybrid biosensor is fabricated using conventional CMOS technology, which has the potential advantage of high density and low noise performance. The biosensor shows a current response of 5.74 decades per pH for pH detection, which is 2.5 × 10(5) times larger than that of a single SiNW sensor. In addition, we demonstrate charged polymer detection using the biosensor, with a high current change of 4.5 × 10(5) with a 500 nM concentration of poly(allylamine hydrochloride). In addition, we demonstrate a wide dynamic range can be obtained by adjusting the liquid gate voltage. We expect that this biosensor will be advantageous and practical for biosensor applications which requires lower noise, high speed, and high density. PMID:26197105

  1. Comparison of the 2D and 3D Nanostructured Lectin-Based Biosensors for In Situ Detection of Sialic Acid on Glycoproteins

    PubMed Central

    Bertok, Tomas; Sediva, Alena; Vikartovska, Alica; Tkac, Jan

    2016-01-01

    We present here comparison of a build-up of two ultrasensitive lectin biosensors based on 2D or 3D architecture. A 2D lectin biosensor was prepared by a covalent immobilisation of lectin Sambucus nigra agglutinin (SNA) recognising sialic acid directly on a mixed self-assembled monolayer (SAM) on planar gold surfaces. A 3D biosensor was prepared by covalent immobilisation of SNA lectin on a mixed SAM layer formed on gold nanoparticles. Surface plasmon resonance technique allowed to follow kinetics of a mixed SAM (1:1 mixture of 11-mercaptoundecanoic acid and 6-mercaptohexanol) formation on a bare gold electrode and on an electrode modified by 5 nm and 20 nm gold nanoparticles (AuNPs). Results from the study revealed that a mixed SAM formation is slower on surfaces with increased curvature, the process of SAM formation on all surfaces is completed within 6 min, but a density of thiols on such surfaces differs significantly. Quartz crystal microbalance experiments showed that a surface density of immobilised lectin of (2.53 ± 0.01) pmol cm-2 was higher on planar gold surface compared to the surface modified by 20 nm AuNPs with a surface density of (0.94 ± 0.01) pmol cm-2. Even though a larger amount of SNA lectin was immobilised on a surface of the 2D biosensor compared to the 3D biosensor, lectin molecules immobilised on AuNPs were more accessible for its analytes – glycoproteins fetuin and asialofetuin, containing different amount of sialic acid on the protein surface. Most likely a better accessibility of lectin for its analytes on a 3D surface and proper interfacial properties of a 3D surface are behind unprecedented detection limit down to aM level for the lectin biosensor based on such a nanoscale tuned interface.

  2. Electrochemical Glucose Biosensor of Platinum Nanospheres Connected by Carbon Nanotubes

    PubMed Central

    Claussen, Jonathan C.; Kim, Sungwon S.; Haque, Aeraj ul; Artiles, Mayra S.; Porterfield, D. Marshall; Fisher, Timothy S.

    2010-01-01

    Background Glucose biosensors comprised of nanomaterials such as carbon nanotubes (CNTs) and metallic nanoparticles offer enhanced electrochemical performance that produces highly sensitive glucose sensing. This article presents a facile biosensor fabrication and biofunctionalization procedure that utilizes CNTs electrochemically decorated with platinum (Pt) nanospheres to sense glucose amperometrically with high sensitivity. Method Carbon nanotubes are grown in situ by microwave plasma chemical vapor deposition (MPCVD) and electro-chemically decorated with Pt nanospheres to form a CNT/Pt nanosphere composite biosensor. Carbon nanotube electrodes are immobilized with fluorescently labeled bovine serum albumin (BSA) and analyzed with fluorescence microscopy to demonstrate their biocompatibility. The enzyme glucose oxidase (GOX) is immobilized onto the CNT/Pt nanosphere biosensor by a simple drop-coat method for amperometric glucose sensing. Results Fluorescence microscopy demonstrates the biofunctionalization capability of the sensor by portraying adsorption of fluorescently labeled BSA unto MPCVD-grown CNT electrodes. The subsequent GOX–CNT/Pt nanosphere biosensor demonstrates a high sensitivity toward H2O2 (7.4 μA/mM/cm2) and glucose (70 μA/mM/cm2), with a glucose detection limit and response time of 380 nM (signal-to-noise ratio = 3) and 8 s (t90%), respectively. The apparent Michaelis–Menten constant (0.64 mM) of the biosensor also reflects the improved sensitivity of the immobilized GOX/nanomaterial complexes. Conclusions The GOX–CNT/Pt nanosphere biosensor outperforms similar CNT, metallic nanoparticle, and more conventional carbon-based biosensors in terms of glucose sensitivity and detection limit. The biosensor fabrication and biofunctionalization scheme can easily be scaled and adapted for microsensors for physiological research applications that require highly sensitive glucose sensing. PMID:20307391

  3. Integrated Biosensor Systems for Ethanol Analysis

    NASA Astrophysics Data System (ADS)

    Alhadeff, Eliana M.; Salgado, Andrea M.; Cós, Oriol; Pereira, Nei; Valero, Francisco; Valdman, Belkis

    Different integrated systems with a bi-enzymatic biosensor, working with two different methods for ethanol detection—flow injection analysis (FIA) or sequential injection analysis (SIA)—were developed and applied for ethanol extracted from gasohol mixtures, as well as for samples of alcoholic beverages and fermentation medium. A detection range of 0.05-1.5 g ethanol/l, with a correlation coefficient of 0.9909, has been reached when using FIA system, working with only one microreactor packed with immobilized alcohol oxidase and injecting free horseradish peroxidase. When using both enzymes, immobilized separately in two microreactors, the detection ranges obtained varied from 0.001 to 0.066 g ethanol/l, without on-line dilution to 0.010-0.047 g ethanol/l when a 1:7,000 dilution ratio was employed, reaching correlation coefficients of 0.9897 and 0.9992, respectively. For the integrated biosensor SIA system with the stop-flow technique, the linear range was 0.005-0.04 g/l, with a correlation coefficient of 0.9922.

  4. A biosensor system using nickel ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Prachi; Rathore, Deepshikha

    2016-05-01

    NiFe2O4 ferrite nanoparticles were synthesized by chemical co-precipitation method and the structural characteristics were investigated using X-ray diffraction technique, where single cubic phase formation of nanoparticles was confirmed. The average particle size of NiFe2O4 was found to be 4.9 nm. Nanoscale magnetic materials are an important source of labels for biosensing due to their strong magnetic properties which are not found in biological systems. This property of the material was exploited and the fabrication of the NiFe2O4 nanoparticle based biosensor was done in the form of a capacitor system, with NiFe2O4 as the dielectric material. The biosensor system was tested towards different biological materials with the help of electrochemical workstation and the same was analysed through Cole-Cole plot of NiFe2O4. The performance of the sensor was determined based on its sensitivity, response time and recovery time.

  5. Microfabrication of biosensors for neurotransmitter analysis

    NASA Astrophysics Data System (ADS)

    Tan, Weihong; Cordek, Julia; Liu, Xiaojing; Gross, Brooks; Liesenfeld, Bernd

    1999-06-01

    We have developed ultrasensitive biosensors for the analysis of neurotransmitters such as glutamate, GABA and lactate. These sensors have micrometer to submicrometer sizes. They are based on biomolecule immobilization on optical fiber probe surfaces. The miniaturized fiber probes are fabricated by either pulling or etching conventional optical fibers. For example, surface immobilized glutamate dehydrogenase (GDH) is being used for glutamate analysis. GDH has been directly immobilized onto an optical fiber probe surface through a new optical fiber sensor fabrication technique using covalent binding mechanisms. None of the direct or indirect physical confinement methods, such as mechanical confinement, gel trapping or membrane immobilization, has been used for the sensor preparation. An optical fiber surface is initially activated by silanization, which adds amine groups (-NH2) to the surface. We then affix functional groups -CHO to the optical fiber surface by employing a bifunctional cross-linking agent, glutaraldehyde. The amino acids of GDH enzyme molecules (or other biomolecules) readily attach to these free -CHO groups on the fiber surface. The sensor is able to detect its substrate, glutamate, by monitoring the fluorescence of reduced nicotinamide adenine dinucleotide (NADH), a product of the reaction between nicotinamide adenine dinucleotide (NAD+) and glutamate. Similar procedures and principle have been used for the development of lactate and GABA sensors. Our biomolecule based biosensors have been applied to the study of single living cell neurophysiological responses.

  6. Development of a functionalized Xenon biosensor

    SciTech Connect

    Spence, Megan M.; Ruiz, E. Janette; Rubin, Seth M.; Lowery, Thomas J.; Winssinger, Nicolas; Schultz, Peter G.; Wemmer, David E.; Pines, Alexander

    2004-03-25

    NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of remote amplified detection. Here we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of functionalized xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

  7. Development of a Pseudomonas aeruginosa Agmatine Biosensor.

    PubMed

    Gilbertsen, Adam; Williams, Bryan

    2014-12-01

    Agmatine, decarboxylated arginine, is an important intermediary in polyamine production for many prokaryotes, but serves higher functions in eukaryotes such as nitric oxide inhibition and roles in neurotransmission. Pseudomonas aeruginosa relies on the arginine decarboxylase and agmatine deiminase pathways to convert arginine into putrescine. One of the two known agmatine deiminase operons, aguBA, contains an agmatine sensitive TetR promoter controlled by AguR. We have discovered that this promoter element can produce a titratable induction of its gene products in response to agmatine, and utilized this discovery to make a luminescent agmatine biosensor in P. aeruginosa. The genome of the P. aeruginosa lab strain UCBPP-PA14 was altered to remove both its ability to synthesize or destroy agmatine, and insertion of the luminescent reporter construct allows it to produce light in proportion to the amount of exogenous agmatine applied from ~100 nM to 1mM. Furthermore it does not respond to related compounds including arginine or putrescine. To demonstrate potential applications the biosensor was used to detect agmatine in spent supernatants, to monitor the development of arginine decarboxylase over time, and to detect agmatine in the spinal cords of live mice. PMID:25587430

  8. Miniaturized thin film glutamate and glutamine biosensors.

    PubMed

    Moser, I; Jobst, G; Aschauer, E; Svasek, P; Varahram, M; Urban, G; Zanin, V A; Tjoutrina, G Y; Zharikova, A V; Berezov, T T

    1995-01-01

    Integrated thin film biosensors were developed for the simultaneous measurement of L-glutamine and L-glutamate in a mu-flow cell. Due to a novel glutaminase with an activity optimum in the neutral pH range, direct monitoring of glutamine in a mammalian cell culture medium could be performed. The glutamine bienzyme sensor was prepared by co-immobilization of glutaminase with glutamate oxidase within a photopatterned poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel membrane. The sensor response was linear in the concentration range of 50 mumol to 10 mmol glutamine/l. Additionally, a glutamate biosensor was integrated on the sensor chip for difference measurement of possible glutamate interferences. The sensor-chip could be used for at least 300 measurements without any alteration in the performance of its sensors. A new sensor-chip with an integrated flow cell provided the possibility of simultaneous measurement of four different parameters at a cell volume of 1 microliter. In order to complete the microsystem, and in order to obtain a "lab on chip", a battery operated surface mounted device (SMD) potentiostat was developed. PMID:7612205

  9. Cholinesterase based amperometric biosensors for assay of anticholinergic compounds

    PubMed Central

    Pohanka, Miroslav

    2009-01-01

    Biosensors are analytical devices being approachable for multiple analytes assay. Here, biosensors with intercepted acetylcholinesterase (AChE) or butyrylcholinesterase (BChE) are presented as tool for assay of anticholinergic compounds such as pesticides, nerve agents and some natural toxins. Principle of assay is based on evaluation of cholinesterase activity and its pertinent decrease in presence of analyte. Nerve agents, pesticides, anticholinergic drugs useable for treatment of Alzheimer′s disease as well as myasthenia gravis and aflatoxins are enlisted as compounds simply analyzable by cholinesterase biosensors. PMID:21217847

  10. Development of a multiarray biosensor for DNA diagnostics

    SciTech Connect

    Vo-Dinh, T.; Isola, N.; Alarie, J.P.; Landis, D.; Griffin, G.D.; Allison, S.

    1998-11-01

    This work involves the development and evaluation of a multiarray biosensor for DNA diagnostics. The evaluation of various system components developed for the biosensor is discussed. The DNA probes labeled with visible and near infrared (NIR) dyes are evaluated. The detection system uses a two-dimensional charge-coupled device (CCD). Examples of application of gene probes in DNA hybridization experiments and in biomedical diagnosis (detection of the p53 cancer gene) are presented to illustrate the usefulness and potential of the biosensor device.

  11. Design of a Highly Specific And Noninvasive Biosensor Suitable for Real-Time in Vivo Imaging of Mercury (II) Uptake

    SciTech Connect

    Chapleau, R.R.; Blomberg, R.; Ford, P.C.; Sagermann, M.

    2009-05-12

    Mercury is a ubiquitous pollutant that when absorbed is extremely toxic to a wide variety of biochemical processes. Mercury (II) is a strong, invisible poison that is rapidly absorbed by tissues of the intestinal tract, kidneys, and liver upon ingestion. In this study, a novel fluorescence-based biosensor is presented that allows for the direct monitoring of the uptake and distribution of the metal under noninvasive in vivo conditions. With the introduction of a cysteine residue at position 205, located in close proximity to the chromophore, the green fluorescent protein (GFP) from Aequorea victoria was converted into a highly specific biosensor for this metal ion. The mutant protein exhibits a dramatic absorbance and fluorescence change upon mercuration at neutral pH. Absorbance and fluorescence properties with respect to the metal concentration exhibit sigmoidal binding behavior with a detection limit in the low nanomolar range. Time-resolved binding studies indicate rapid subsecond binding of the metal to the protein. The crystal structures obtained of mutant eGFP205C indicate a possible access route of the metal into the core of the protein. To our knowledge, this engineered protein is a first example of a biosensor that allows for noninvasive and real-time imaging of mercury uptake in a living cell. A major advantage is that its expression can be genetically controlled in many organisms to enable unprecedented studies of tissue specific mercury uptake.

  12. Glucose Biosensors: An Overview of Use in Clinical Practice

    PubMed Central

    Yoo, Eun-Hyung; Lee, Soo-Youn

    2010-01-01

    Blood glucose monitoring has been established as a valuable tool in the management of diabetes. Since maintaining normal blood glucose levels is recommended, a series of suitable glucose biosensors have been developed. During the last 50 years, glucose biosensor technology including point-of-care devices, continuous glucose monitoring systems and noninvasive glucose monitoring systems has been significantly improved. However, there continues to be several challenges related to the achievement of accurate and reliable glucose monitoring. Further technical improvements in glucose biosensors, standardization of the analytical goals for their performance, and continuously assessing and training lay users are required. This article reviews the brief history, basic principles, analytical performance, and the present status of glucose biosensors in the clinical practice. PMID:22399892

  13. Preparation of Amperometric Glucose Biosensor Based on 4-Mercaptobenzoic Acid

    NASA Astrophysics Data System (ADS)

    Wang, Huihui; Ohnuki, Hitoshi; Endo, Hideaki; Izumi, Mitsuru

    A novel glucose biosensor was fabricated by a combination of a self-assembled monolayer (SAM) of 4-mercaptobenzoic acid and the Langmuir-Blodgett (LB) technique. Because of the catalysis of Prussian Blue contained in the LB film layers, the prepared amperometric biosensor worked at a very low potential range around 0.0 V vs. Ag/AgCl. The optimum operating conditions for glucose biosensor were investigated by varying the glucose oxidase immobilization time, the applied potential and the pH of buffer solution. The steady-state current responses of the glucose biosensor showed a good linear relationship to glucose concentrations from 0.1 mM to 154 mM.

  14. Modelling of amperometric biosensor used for synergistic substrates determination.

    PubMed

    Simelevicius, Dainius; Baronas, Romas; Kulys, Juozas

    2012-01-01

    In this paper the operation of an amperometric biosensor producing a chemically amplified signal is modelled numerically. The chemical amplification is achieved by using synergistic substrates. The model is based on non-stationary reaction-diffusion equations. The model involves three layers (compartments): a layer of enzyme solution entrapped on the electrode surface, a dialysis membrane covering the enzyme layer and an outer diffusion layer which is modelled by the Nernst approach. The equation system is solved numerically by using the finite difference technique. The biosensor response and sensitivity are investigated by altering the model parameters influencing the enzyme kinetics as well as the mass transport by diffusion. The biosensor action was analyzed with a special emphasis to the effect of the chemical amplification. The simulation results qualitatively explain and confirm the experimentally observed effect of the synergistic substrates conversion on the biosensor response. PMID:22666066

  15. Modelling of Amperometric Biosensors in the Case of Substrate Inhibition

    PubMed Central

    Kulys, Juozas; Baronas, Romas

    2006-01-01

    The response of an amperometric biosensor at mixed enzyme kinetics and diffusion limitations was modelled digitally in the case of substrate inhibition. Digital simulations were carried out using a finite difference technique. Calculations showed complex kinetics of biosensor response. At low enzyme activity and substrate concentration (S0), the response of the sensor looks like it is limited by a simple substrate diffusion. At substrate concentration comparable to the Michaelis-Menten constant (KM), the response change shows a maximal value. A sharp response change was indicated at high enzyme activity and high (4.9 > S0/KM > 4.5) substrate concentration. This was explained by multi-concentration of substrate generation inside the enzyme layer. This conclusion was confirmed by the analytical solution of the simplified biosensor model with external diffusion limitation at steady-state conditions. The complex kinetics of response change produces different calibration graphs for biosensor response at transition and steady state.

  16. Modelling of Amperometric Biosensor Used for Synergistic Substrates Determination

    PubMed Central

    Simelevicius, Dainius; Baronas, Romas; Kulys, Juozas

    2012-01-01

    In this paper the operation of an amperometric biosensor producing a chemically amplified signal is modelled numerically. The chemical amplification is achieved by using synergistic substrates. The model is based on non-stationary reaction-diffusion equations. The model involves three layers (compartments): a layer of enzyme solution entrapped on the electrode surface, a dialysis membrane covering the enzyme layer and an outer diffusion layer which is modelled by the Nernst approach. The equation system is solved numerically by using the finite difference technique. The biosensor response and sensitivity are investigated by altering the model parameters influencing the enzyme kinetics as well as the mass transport by diffusion. The biosensor action was analyzed with a special emphasis to the effect of the chemical amplification. The simulation results qualitatively explain and confirm the experimentally observed effect of the synergistic substrates conversion on the biosensor response. PMID:22666066

  17. Engineered PQQ-Glucose Dehydrogenase as a Universal Biosensor Platform.

    PubMed

    Guo, Zhong; Murphy, Lindy; Stein, Viktor; Johnston, Wayne A; Alcala-Perez, Siro; Alexandrov, Kirill

    2016-08-17

    Biosensors with direct electron output hold promise for nearly seamless integration with portable electronic devices. However, so far, they have been based on naturally occurring enzymes that significantly limit the spectrum of detectable analytes. Here, we present a novel biosensor architecture based on analyte-driven intermolecular recombination and activity reconstitution of a re-engineered component of glucometers: PQQ-glucose dehydrogenase. We demonstrate that this sensor architecture can be rapidly adopted for the detection of immunosuppressant drugs, α-amylase protein, or protease activity of thrombin and Factor Xa. The biosensors could be stored in dried form without appreciable loss of activity. We further show that ligand-induced activity of the developed biosensors could be directly monitored by chronoamperometry, enabling construction of disposable sensory electrodes. We expect that this architecture could be expanded to the detection of other biochemical activities, post-translational modifications, nucleic acids, and inorganic molecules. PMID:27463000

  18. Advances in the manufacturing, types, and applications of biosensors

    NASA Astrophysics Data System (ADS)

    Ravindra, Nuggehalli M.; Prodan, Camelia; Fnu, Shanmugamurthy; Padronl, Ivan; Sikha, Sushil K.

    2007-12-01

    In recent years, there have been significant technological advancements in the manufacturing, types, and applications of biosensors. Applications include clinical and non-clinical diagnostics for home, bio-defense, bio-remediation, environment, agriculture, and the food industry. Biosensors have progressed beyond the detection of biological threats such as anthrax and are finding use in a number of non-biological applications. Emerging biosensor technologies such as lab-on-a-chip have revolutionized the integration approaches for a very flexible, innovative, and user-friendly platform. An overview of the fundamentals, types, applications, and manufacturers, as well as the market trends of biosensors is presented here. Two case studies are discussed: one focused on a characterization technique—patch clamping and dielectric spectroscopy as a biological sensor—and the other about lithium phthalocyanine, a material that is being developed for in-vivo oxymetry.

  19. Crystal Creations.

    ERIC Educational Resources Information Center

    Whipple, Nona; Whitmore, Sherry

    1989-01-01

    Presents a many-faceted learning approach to the study of crystals. Provides instructions for performing activities including crystal growth and patterns, creating miniature simulations of crystal-containing rock formations, charcoal and sponge gardens, and snowflakes. (RT)

  20. Nucleopolyhedrovirus infection and/or parasitism by Microplitis pallidipes Szepligeti affect hemocyte apoptosis of Spodoptera exigua (Hübner) larvae.

    PubMed

    Wan, Nian-Feng; Ji, Xiang-Yun; Zhang, Hao; Yang, Jun-Hua; Jiang, Jie-Xian

    2015-11-01

    We determined the effects of parasitism by the endoparasitoid Microplitis pallidipes Szepligeti and/or nucleopolyhedrovirus (NPV) infection on hemocyte apoptosis of Spodoptera exigua (Hübner) larvae. Compared to healthy (control) larvae, larvae that were parasitized, virus-infected, or both all showed a significant increase in hemocyte apoptosis during 48-h observation period. The peaks of hemocyte apoptosis in parasitized, virus-infected and parasitized+infected larvae were at 12, 24 and 48 h after treatment, and were 86.7±1.9, 87.4±3.6 and 76.5±1.6%, respectively. Meanwhile, compared to parasitized larvae, hemocyte apoptosis in jointly parasitized and infected larvae increased by 12.9%, 18.7% and 2.8% at 8, 36 and 48 h respectively, and decreased by 39.0% and 9.1% at 12 and 24h. Compared to virus-infected larvae, hemocyte apoptosis in jointly parasitized and infected larvae increased by 13.4%, 2.4% and 15.3% at 8, 36 and 48 h, respectively, and decreased by 4.0% and 29.9% at 12 and 24h. Our study found that joint and separate parasitism and SeNPV infection induced hemocyte apoptosis of S. exigua larvae. It also revealed that NPV infection promoted host hemocyte apoptosis induced by parasitism at early egg and larval stages of M. pallidipes in host larvae, but inhibited the same effect at late egg stage of M. pallidipes in host larvae, and that parasitism promoted host hemocyte apoptosis induced by NPV infection at early egg and larval stages of M. pallidipes in host larvae, but inhibited the same effect at late egg stage of M. pallidipes in host larvae. PMID:26470677