Search results for "biosensor"
showing 10 items of 236 documents
Porous silicon photoluminescence biosensor for rapid and sensitive detection of toxins
2017
A rapid and low cost photoluminescence (PL) immunosensor for the determination of low concentrations of Ochratoxin A(OTA) and Aflatoxine B1 (AfB1) has been developed. This biosensor was based on porous silicon (PSi) fabricated by metal-assisted chemical etching (MACE) and modified by antibodies against OTA/AfB1 (anti-OTA/anti-AfB1). Biofunctionalization method of the PSi surface by anti-OTA/ anti-AfB1 was developed. The changes of the PL intensity after interaction of the immobilized anti-OTA/anti-AfB1with OTA/AfB1 antigens were used as biosensor signal, allowing sensitive and selective detection of OTA/AfB1 antigens in BSA solution. The sensitivity of the reported optical biosensor towards…
Nanomaterial-based cocaine aptasensors.
2015
Up to now, many different methods have been developed for detection of cocaine, but most of these methods are usually time-consuming, tedious and require special or expensive equipment. Therefore, the development of simple, sensitive and rapid detection methods is necessary. In the last decade, aptamers have been used as a new biosensor platform for detection of cocaine in different samples. Aptamers are artificial single-stranded DNA or RNA oligonucleotides capable of binding to specific molecular targets with high affinity and if integrated to nanomaterials, it may lead in precise methods for cocaine detection in the common laboratories. In this review, recent advances and applications of…
Non-invasive diagnosis of oral cancer: The role of electro-analytical methods and nanomaterials
2017
Abstract Oral cancer is a kind of head and neck cancer and is each cancerous tissue growth located in the oral cavity. Non-invasive early diagnosis of oral cancer is the most effective means to reduce death from this disease or increase the survival time. In this review, various types of electro-analytical methods for detection of oral cancer were discussed. The emphasis is placed on non-invasive detection of oral based on immune-, geno-, cyto-, apta-, and enzyme-biosensing strategies. In the first part of review, various electrochemical immunosensing methods for the detection of common biomarker in oral cancer and examines their potential as a new method were discussed. In the second part …
Early stage screening of breast cancer using electrochemical biomarker detection
2017
Recently researchers have driven their attention in the development of biosensors for breast cancer detection using different biomarkers. This review reports a systematic study of the usefulness of marker-based electrochemical biosensors in breast cancer and its early diagnosis. Also, various types of electro-analytical methods for early stage screening of breast cancer were discussed. The emphasis is placed on immune-, geno- cyto- and enzyme-biosensing strategies. In addition, the advantages offered by some nano-materials in detection of breast cancer biomarkers are illustrated with representative recent examples that highlight the scientific interest in widening the use of new materials/m…
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.
Multi-spectral photoplethysmography biosensor
2011
A photoplethysmography (PPG) signal can provide very useful information about a subject's hemodynamic status in a hospital or home environment. A newly developed portable multi-spectral photoplethysmography device has been used for studies of 11 healthy subjects. The developed optical fiber biosensor comprises one multi-wavelength laser diode (405nm, 660nm and 780nm) and a single photodiode with multi-channel signal output processing and built in Li-ion accumulator; special software was created for visualization and measuring of the MS-PPG signals. ARM7TDMI-S LPC2148, NXP (founded by Philips) 32 bit processor with clock frequency of 60 MHz performs measurement and analysis of the signal.
Oligonucleotide-Hybridization Fiber-Optic Biosensor using a Narrow Bandwidth Long Period Grating
2017
Nanometric narrowband Long Period Gratings (LPG) are investigated for the implementation of improved fiber optic biosensors. The reduction of more than one order of magnitude in the linewidth of the LPG with respect standard LPG at 1500 nm, leads to the improvement of the resolution of the sensor. By selecting the proper fabrication parameters (high numerical aperture, relatively high order mode and large length), LPGs with a 3-dB bandwidth of 1.5 nm were fabricated. The sensitivity of the LPG as a refractometer was calculated, and experimentally characterized in detail. In particular, the LP0,17 and LP0,18 resonances were investigated, in order to select the most suitable one for the bioex…
Development of optical WGM resonators for biosensors
2017
Whispering Gallery Mode (WGM) resonators are very sensitive to nanoparticles attaching to the surface. We simulate this process using COMSOL Wave Optics module. Our spherical WGM resonators are produced by melting a tip of an optical fiber and we measure optical Q factors in the 105 range. Molecular oxygen lines of the air in the 760 nm region are used as reference markers when looking for the shifts of the WGM resonance lines. We demonstrate WGM microresonator surface coating with a layer of ZnO nanorods as well as with polystyrene microspheres. Coatings produce increased contact surface. Additional layer of antigens/antibodies will be coated to make high-specificity biosensors.
Direct measurement of the melting temperature of supported DNA by electrochemical method
2003
The development of biosensors based on DNA hybridization requires a more precise knowledge of the thermodynamics of the hybridization at a solid interface. In particular, the selectivity of hybridization can be affected by a lot of parameters such as the single-strand (ss)DNA density, the pH, the ionic strength or the temperature. The melting temperature, T(m), is in part a function of the ionic strength and of the temperature and therefore provides a useful variable in the control of the selectivity and sensitivity of a DNA chip. The electrochemical technique has been used to determine the T(m) values when the probe is tethered by a DNA self-assembled monolayer (SAM). We have built a speci…
A real time immunoassay in alumina membranes
2014
To date, photonic biosensing with porous membranes has produced slow responses and long sensing times, due to the narrow (less than 100 nm) closed end pores of the membranes used. Recently, polarimetry was used to demonstrate analyte flow through, and real time biosensing in, free-standing porous alumina membranes. Here, we demonstrate how an improved functionalization technology, has for the first time enabled a real-time immunoassay within a porous membrane with a total assay time below one hour. With the new approach, we show a noise floor for individual biosensing measurements of 3.7 ng/ml (25 pM), and a bulk refractive index detection limit of 5×10-6 RIU, with a standard deviation of l…