Search results for "biosensor"

Rational backbone redesign of a fructosyl peptide oxidase to widen its active site access tunnel

2020

Fructosyl peptide oxidases (FPOXs) are enzymes currently used in enzymatic assays to measure the concentration of glycated hemoglobin and albumin in blood samples, which serve as biomarkers of diabetes. However, since FPOX are unable to work directly on glycated proteins, current enzymatic assays are based on a preliminary proteolytic digestion of the target proteins. Herein, to improve the speed and costs of the enzymatic assays for diabetes testing, we applied a rational design approach to engineer a novel enzyme with a wider access tunnel to the catalytic site, using a combination of Rosetta design and molecular dynamics simulations. Our final design, L3_35A, shows a significantly wider …

Complexes of carbon nanotubes with ions and macromolecules : studies on electronic conduction properties

2014

Si photomultipliers for bio-sensing applications

2016

In this paper, silicon photomultipliers (SiPM) are proposed as optical detectors for bio sensing. Optical transduction is the most used detection mechanism in many biosensor applications, such as DNA microarray and real-time polymerase chain reaction. The performances of a 25 pixels device used for both applications are studied. The results confirm that the SiPM is more sensitive than the traditionally employed detectors. In fact, it is able to experimentally detect 1 nM and 100 fM of fluorophore concentrations in dried samples and solutions, respectively. We present and discuss in details the detector configuration and its characterization as fluorescence detector for bio sensing.

Toxicity of gold-nanoparticles: Synergistic effects of shape and surface functionalization on micromotility of epithelial cells

2010

Nanoparticle exposure is monitored by a combination of two label-free and non-invasive biosensor devices which detect cellular shape and viscoelasticity (quartz crystal microbalance), cell motility and the dynamics of epithelial cell-cell contacts (electric cell-substrate impedance sensing). With these tools we have studied the impact of nanoparticle shape on cellular physiology. Gold (Au) nanoparticles coated with CTAB were synthesized and studied in two distinct shapes: Spheres with a diameter of (43 ± 4) nm and rods with a size of (38 ± 7) nm × (17 ± 3) nm. Dose-response experiments were accompanied by conventional cytotoxicity tests as well as fluorescence and dark-field microscopy to v…

Ion-Selective Organic Electrochemical Transistors

2014

Ion-selective organic electrochemical transistors with sensitivity to potassium approaching 50 μA dec(-1) are demonstrated. The remarkable sensitivity arises from the use of high transconductance devices, where the conducting polymer is in direct contact with a reference gel electrolyte and integrated with an ion-selective membrane.

Integrated optic Surface Plasmon Resonance Measurements in Glass substrates

2007

The surface plasmon resonance (SPR) technique is an optical method that can be used to measure the refractive index of organic nano-layers adsorbed on a thin metal film. Although there are many techniques for measuring biomolecular interactions, SPR-based techniques play a central role in many current biosensing experiments, since they are most suited to sensitive and quantitative kinetic measurements. Here we give some results from the analysis and numerical elaboration of SPR data regarding the flow of different solutions with refractive indexes in the range of interest (1-1.4). After a brief discussion of the principles of SPR and of waveguide fabrication technique, we give a description…

Improving the Design of Ion Track-Based Biosensors

2018

In the last decade we had developed new types of biosensors, by cladding the inner walls of transparent etched swift heavy ion tracks in thin polymer foils with enzymes. The enzymatic reaction products of appropriate analytes penetrating into narrow tracks are enriched in the track’s confinement, and they change the electrical track properties if their charge states differ from those of the analytes. It was yet unknown how to design these sensors so that their best efficiency and highest possible sensitivity is achieved. This requires the accurate knowledge of the optimum track radius and the degree of product enrichment within the tracks. These questions were answered by appropriate experi…

Aptamer-based assay of biomolecules: Recent advances in electro-analytical approach

2017

Electrochemical aptasensors, which are based on the specificity of aptamer-target recognition, with electrochemical transduction for analytical purposes have received particular attention due to their high sensitivity and selectivity, simple instrumentation, as well as low production cost. This review summarizes advances from 2009 to January 2017 in the development of electrochemical aptasensors for biological molecules, including small molecules, nucleic acids, and proteins. Various aptasensing strategies are assessed according to their potential for reaching relevant limits of sensitivity, specificity, and degrees of multiplexing. Furthermore, we address the remaining challenges and oppor…

Visible Photoluminescence of Variable-Length Zinc Oxide Nanorods Embedded in Porous Anodic Alumina Template for Biosensor Applications

2021

Zinc oxide (ZnO) and porous anodic aluminum oxide (PAAO) are technologically important materials, rich with features that are of interest in optical applications, for example, in light-emitting and sensing devices. Here, we present synthesis method of aligned ZnO nanorods (NR) with 40 nm diameter and variable length in 150 to 500 nm range obtained by atomic layer deposition (ALD) of ZnO in pores of continuously variable thickness PAAO. The relative intensity of yellow (1.99 eV), green (2.35 eV), and blue (2.82 eV) photoluminescence (PL) components originating from the different types of defects, varied with non-monotonic dependency on the composite film thickness with a Fabry–Pérot like mod…

Nanoporainu anodēta alumīnija oksīdu saturošu vairākslāņu optisko pārklājumu sintēze un raksturošana

2021

Nanoporainu anodēta alumīnija oksīdu saturošu vairākslāņu optisko pārklājumu sintēze un raksturošana. Dutovs A., zinātniskie vadītāji prof. Dr. Chem., prof. Erts D. un vadošais pētnieks doc. Dr. Phys. Prikulis J. Konsultanti vadošais pētnieks Dr. Chem. Popļausks R. un pētnieks M.Sc. Biol. Maļinovskis U. Maģistra darbs, 49 lappuses, 21 attēls, 3 tabulas, 56 literatūras avoti. Latviešu valodā. Porains anodēts alumīnija oksīds ir optiski aktīva viela, uz kura pamatnes ir iespējams iegūt dažādus nanostrukturētus materiālus. Cinka oksīds, pateicoties savām izteiktajām fotoluminiscentām īpašībām, ir plaši pētīts pusvadītājs sensoru substrātu veidošanai. Cēlmetālu nanodaļiņu pārklāšana ar grafēnu …