Polyethylene imine-based receptor immobilization for label free bioassays

Polyethylene imine (PEI) based immobilization of antibodies is described and the concept is proved on the label free assay of C-Reactive Protein (CRP). This novel immobilization method is composed of a hyperbranched PEI layer which was deposited at a high pH (9.5) on the sensor surface. The free amino groups of PEI were derivatized with neutravidin by Biotin N-hydroxysuccinimide ester and the biotinylated anti-CRP antibody immobilized on this layer. Direct binding assay of recombinant CRP was successfully performed in the low μg/ml concentrations using a label free optical waveguide biosensor

A comprehensive review: materials for the fabrication of optical fiber refractometers based on lossy mode resonance

Lossy mode resonance based sensors have been extensively studied in recent years. The versatility of the lossy mode resonance phenomenon has led to the development of sensors based on different configurations that make use of a wide range of materials. The coating material is one of the key elements in the performance of a refractometer. This review paper intends to provide a global view of the wide range of coating materials available for the development of lossy mode resonance based refractometers.This research was funded by the Spanish Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (TEC2016-78047-R), the Public University of Navarra (PJUPNA26), and the Spanish Ministry of Universities (FPU15/05663)

High-Performance PVC Gel for Adaptive Micro-Lenses with Variable Focal Length.

This paper presents a bio-inspired adaptive micro-lens with electrically tunable focus made of non-ionic high-molecular-weight polyvinyl chloride (PVC) gel. The optical device mimics the design of the crystalline lens and ciliary muscle of the human eye. It consists of a plano-convex PVC gel micro-lens on Indium Tin Oxide (ITO) glass, confined with an annular electrode operating as an artificial ciliary muscle. Upon electrical activation, the electroactive adhesive force of the PVC gel is exerted on the annular anode electrode, which reduces the sagittal height of the plano-convex PVC gel lens, resulting in focal length variation of the micro-lens. The focal length increases from 3.8 mm to 22.3 mm as the applied field is varied from 200 V/mm to 800 V/mm, comparable to that of the human lens. The device combines excellent optical characteristics with structural simplicity, fast response speed, silent operation, and low power consumption. The results show the PVC gel micro-lens is expected to open up new perspectives on practical tunable optics

Hybrid Optical Fiber Sensor And Artificial Neural Networks System For Bioethanol Quality Control And Productivity Enhancement

Bioethanol is produced by bio-chemical process that converts sugar or biomass feedstock into ethanol. After bio-chemical process, the solution is distilled under controlled conditions of pressure and temperature, in order to obtain an ethanol-water solution. However, the ethanol concentration analysis is generally performed off-line and, sometimes, a re-distillation process becomes necessary. In this research, an optical apparatus based on Fresnel reflection has been used in combination with artificial neural networks for determination of bioethanol concentration in hydro-alcoholic solution at any temperature. The volumetric concentration and temperature effect was investigated. This intelligent system can effectively detect and update in real-time the correction of distillation parameters to reduce losses of bioethanol and also to improve the quality in a production plant.7004Buggy, S.J., Murphy, R.P., James, S.W., Tatam, R.P., Cure monitoring of a UV cured epoxy resin using a long period grating Mach-Zehnder interferometer (2007) Proceedings of SPIE, 6619, pp. 66190VChehura, E., James, S.W., Tatam, R.P., Simultaneous, independent measurement of temperature and strain using a tilted fibre Bragg grating (2007) Proceedings of SPIE, 6619, pp. 66190IChong, J.H., Shum, P., Haryono, H., Yohana, A., Rao, M.K., Lu, C., Zhu, Y., Measurements of refractive index sensitivity using long-period grating refractometer (2004) Optics Communications, 229, pp. 65-69Su, H., Huang, X.G., Fresnel-reflection-based fiber sensor for on-line measurement of solute concentration in solutions (2007) Sensors and Actuators B: Chemical, 126 (2), pp. 579-582Meneghini, C., Caron, S., Proulx, A., Émond, F., Paradis, P., Paré, C., Fougères, A., Ethanol concentration measurement by Raman spectroscopy in liquid-core microstructured optical fiber (2007) Proceedings of SPIE, 6619, pp. 66191ULiang, W., Huang, Y., Xu, Y., Lee, R.K., Yariv, A., Highly sensitive fiber Bragg grating refractive index sensors (2005) Appl. Phys. Lett, 86, p. 151122Kheshgi, H.S., Prince, R.C., Sequestration of fermentation CO2 from ethanol production (2005) Energy, 30, pp. 1865-1871Olsson, L., Hahn-Hagerdal, B., Fermentation of lignocellulosic hydrolysates for ethanol production (1996) Enzyme and Microbial Technology, 18, pp. 312-331Natural Gas and Biofuel, ANP Resolution, (36 BRand 2005). , www.anp.gov, National Agency of PetroleumTakeishi, R.T., Gusken, E., de Souza, H.G.E., Meirelles, B.M., Suzuki, C.K., Study of the temperature effects in the alcohol-gasoline blend ratio determined by optical sensor (2007) 4th Brazilian Conference of R&D in Petroleum and Gas, , Proceedings, Campinas-SP, CD-RomBishop, C.M., (1995) Neural Networks for Pattern Recognition, , Oxford: Oxford University PressChen, S., Billings, S.A., Neural networks for nonlinear dynamic system modelling and identification (1992) International Journal of Control, 56 (2), pp. 319-346Dempsey, G.L., Alt, N.L., Olson, B.A., Alig, J.S., Control sensor linearization using a microcontroller-based neuralnetwork (1997) IEEE Intern. Conf. on Computational Cybernetics and Simulation, 4 (12-15), pp. 3078-3083. , PPLin, T.K., Chang, K.C., Lin, Y.B., Active Control with Optical Fiber Sensors and Neural Networks. II: Experimental Verification (2006) Journal of Structural Engineering, 132 (8), pp. 1304-1313Lin, T.K., Chang, K.C., Chung, L.L., Lin, Y.B., Active Control with Optical Fiber Sensors and Neural Networks. I: Theoretical Analysis (2006) Journal of Structural Engineering, 132 (8), pp. 1293-1303Rumelhart, D.E., Hinton, G., Willians, R., Learning Representation by Back-Propagation Errors (1986) Parallel Distributed Processing, 323 (9), pp. 533-536Kolodner, P., Williams, H., Moe, C., Optical measurement of the soret coefficient of ethanol/water solutions (1988) J. Chem. Phys, 88 (10), pp. 6512-6524Pan, S., Saghir, M.Z., Kawaji, M., Jiang, C.G., Yan, Y., Theoretical approach to evaluate thermodiffusion in aqueous alkanol solutions (2007) J. of Chemical Physics, 126, p. 014502González-Salgado, D., Nezbeda, I., Excess properties of aqueous mixtures of methanol: Simulation versus experiment (2006) Fluid Phase Equilibria, 240 (2), pp. 161-166. , PPPandey, J.D., Vyas, V., Jain, P., Dubey, G.P., Tripathi, N., Dey, R., Speed of sound, viscosity and R.I. of multicomponent systems: Theoretical predictions from the properties of pure components (1999) J. of Mol. Liq, 81, pp. 123-133C. K.Suzuki, E. Gusken, A. C. Mercado, E. Fujiwara, E. Ono, Fiber Optics Sensing System For Liquid Fuels, INPI Patent, Prot. 018070050521, 200

Recent advances in optical fiber devices for microfluidics integration

This paper examines the recent emergence of miniaturized optical fiber based sensing and actuating devices that have been successfully integrated into fluidic microchannels that are part of microfluidic and lab-on-chip systems. Fluidic microsystems possess the advantages of reduced sample volumes, faster and more sensitive biological assays, multi-sample and parallel analysis, and are seen as the de facto bioanalytical platform of the future. This paper considers the cases where the optical fiber is not merely used as a simple light guide delivering light across a microchannel, but where the fiber itself is engineered to create a new sensor or tool for use within the environment of the fluidic microchannel

3D correlative single-cell imaging utilizing fluorescence and refractive index tomography

Cells alter the path of light, a fact that leads to well-known aberrations in single cell or tissue imaging. Optical diffraction tomography (ODT) measures the biophysical property that causes these aberrations, the refractive index (RI). ODT is complementary to fluorescence imaging and does not require any markers. The present study introduces RI and fluorescence tomography with optofluidic rotation (RAFTOR) of suspended cells, quantifying the intracellular RI distribution and colocalizing it with fluorescence in 3D. The technique is validated with cell phantoms and used to confirm a lower nuclear RI for HL60 cells. Furthermore, the nuclear inversion of adult mouse photoreceptor cells is observed in the RI distribution. The applications shown confirm predictions of previous studies and illustrate the potential of RAFTOR to improve our understanding of cells and tissues.Comment: 15 pages, 5 figure

Structure-function analysis of the curli accessory protein CsgE defines surfaces essential for coordinating amyloid fiber formation

Curli amyloid fibers are produced as part of the extracellular biofilm matrix and are composed primarily of the major structural subunit CsgA. The CsgE chaperone facilitates the secretion of CsgA through CsgG by forming a cap at the base of the nonameric CsgG outer membrane pore. We elucidated a series of finely tuned nonpolar and charge-charge interactions that facilitate the oligomerization of CsgE and its ability to transport unfolded CsgA to CsgG for translocation. CsgE oligomerization in vitro is temperature dependent and is disrupted by mutations in the W48 and F79 residues. Using nuclear magnetic resonance (NMR), we identified two regions of CsgE involved in the CsgE-CsgA interaction: a head comprising a positively charged patch centered around R47 and a stem comprising a negatively charged patch containing E31 and E85. Negatively charged residues in the intrinsically disordered N- and C-terminal “tails” were not implicated in this interaction. Head and stem residues were mutated and interrogated using in vivo measurements of curli production and in vitro amyloid polymerization assays. The R47 head residue of CsgE is required for stabilization of CsgA- and CsgE-mediated curli fiber formation. Mutation of the E31 and E85 stem residues to positively charged side chains decreased CsgE-mediated curli fiber formation but increased CsgE-mediated stabilization of CsgA. No single-amino-acid substitutions in the head, stem, or tail regions affected the ability of CsgE to cap the CsgG pore as determined by a bile salt sensitivity assay. These mechanistic insights into the directed assembly of functional amyloids in extracellular biofilms elucidate possible targets for biofilm-associated bacterial infections.Curli represent a class of functional amyloid fibers produced by Escherichia coli and other Gram-negative bacteria that serve as protein scaffolds in the extracellular biofilm matrix. Despite the lack of sequence conservation among different amyloidogenic proteins, the structural and biophysical properties of functional amyloids such as curli closely resemble those of amyloids associated with several common neurodegenerative diseases. These parallels are underscored by the observation that certain proteins and chemicals can prevent amyloid formation by the major curli subunit CsgA and by alpha-synuclein, the amyloid-forming protein found in Lewy bodies during Parkinson’s disease. CsgA subunits are targeted to the CsgG outer membrane pore by CsgE prior to secretion and assembly into fibers. Here, we use biophysical, biochemical, and genetic approaches to elucidate a mechanistic understanding of CsgE function in curli biogenesis