Papers by Keyword: Immunosensor

Abstract: We presented here the development of an immunosensor based on graphene nanoplatelets-modified screen printed carbon electrode (SPCE) with incorporated rabbit IgG on the amino functionalized surface area. In order to improve sensitivity of working electrode, graphene-nanoplatelets solution was fabricated onto surface carbon working electrode. The effect of different (3-aminopropyl) triethoxysilane (APTES) concentrations (0.125, 0.5, 2 and 8% (v/v)) and incubation time of silanization (30, 60 and 90 min) were studied and compared. An electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize our immunosensor based. It is showed that the optimum APTES concentration which provides higher surface coverage and electron transfer rate was 2% concentration (v/v) at 60 min of incubation time. The modified surface was then evaluated by measuring immobilized rabbit IgG via indirect assay using horseradish peroxidase labelled secondary antibody. The optimum detection immobilized IgG was 0.05 mg/mL. These results indicate the potential for amino functionalized graphene nanoplatelets-modified SPCE in detecting protein biomarkers.

Abstract: Rapid-response biosensing systems are necessary to counteract threats due to high-consequence pathogens. A disposable immunosensor suitable for quantitative determination of E.coli O157:H7 in pure cultures was investigated by electrochemical impedance spectroscopy (EIS). Electric responses of this biosensor for different cell concentrations at multi-frequencies were explored utilizing disposable screen-printed silver four-wire interdigitated microelectrodes (IMEs). Additionally, the best response frequency for the detection was studied, and the relationship between the impedance at this frequency and the concentrations of E.coli O157:H7 was established. The results showed that the impedance biosensor showed linearity from 1.15×10³ CFU/mL to 1.15×10⁶ CFU/mL at 100Hz, which yielded the model coefficient to 0.951.

Abstract: An immunosensor is an analytical system consisting of specific immune system molecules coupled to a signal transducer. Immunosensor sensitivity depends on the type of immunorecognition ligands used, immobilization influence on their activity and orientation on the surface. Quartz crystal microbalance with dissipation (QCM-D) was employed to investigate the immobilization of antibodies against bovine leukemia virus antigen gp51 (gp51). Disulphide bridges of antibody hinge region were reduced chemically to yield two half antibody fragments (Frag-Ab), each having a single antigen binding site and free sulfhydryl groups that were used for immobilization. Frag-Ab were immobilized on planar gold and gold nanoparticle (AuNP) modified QCM-D sensor surfaces from initial solutions of different concentrations. Higher Frag-Ab surface density values were obtained on AuNP modified surfaces at all tested antibody concentrations. Frag-Ab/gp51 specific interaction was registered and it was determined that the highest sensitivity was exhibited by Frag-Ab immobilized at the lowest surface desities on both types of investigated surfaces. Specific gp51 interaction with Frag-Ab and non-specific binding to bovine serum albumin modified surfaces were compared by employing Δf/ΔD plots, which could serve as fingerprints of different processes.

Abstract: Recently, nanomaterial based biosensor application has drawn a lot attention among researchers because of specialty to enhance the sensor signal for increasing the sensitivity for detecting and identification of pathogen, viruses and toxic compound in controlling plant disease outbreak effectively. Rice tungro disease (RTD) causes a major problem in rice production and also will effect in the economic loss in the country. Therefore, early detection system is needed to monitor the disease at the early stage of the infection for preventing the disease outbreak in planting area. Lastly, this paper will discuss the current findings in rapid diagnostics using immunosensors technologies with nanomaterial application in enhancing the sensor signal for increasing the detection sensitivity

Abstract: This work describes an approach for the development of two bacteria biosensors based on surface plasmon resonance (SPR) technique. The first biosensor was based on functionalized gold substrate and the second one on immobilized silver nanoparticles. For the first biosensor, the gold substrate was functionalized with acid–thiol using the self-assembled monolayer technique, while the second one was functionalized with silver nanoparticles immobilized on modified gold substrate. A polyclonal anti-Escherichia coli antibody was immobilized for specific (E. coli) bacteria detection. Detection limit with a good reproducibility of 104 and 103 cfu•mL−1 of E. coli bacteria has been obtained for the first biosensor and for the second one respectively.

Abstract: A new electrochemical immunosensor for serum myeloperoxidase (MPO) has been developed based on the self-assembly multilays of multi-walled carbon nanotubes (MWNTs), thionine (THI), gold nanoparticles (GNPs) and chitosanon (CHIT) on the glassy carbon electrode (GCE). The antibody of MPO (anti-MPO) was absorbed on the surface of GNPs monolayer. Horseradish peroxidase (HRP) was employed to block non-specific binding and amplify the response current signal. It was observed that the peak current was linear with the MPO concentration in a range of 2.5-125 µgl-1. The detection limit was 1.425 µgl-1 (S/N=3). Correlation analysis showed that this new immunosensor assay has a significant correlation with enzyme-linked immunosorbent assay (ELISA) (r=0.96, p>0.05) for 40 clinical specimens.

Abstract: A label free impedimetric immunosensor for the determination of aflatoxin B1 (AFB1) was fabricated by immobilizing anti-AFB1 onto Poly o-phenylenediamine (PoPD) electropolymerized film modified gold electrode by glutaraldehyde (GA) cross-linking. An electrochemical interfacial modeling of biomolecular recognition was recommended and reasonably interpreted. EIS technology was employed for the quantitative determination. The linear detection concentration ranges of AFB1 were 0.03~0.1 μg/mL and 0.1~0.7 μg/mL. The detection limit was 2.8×10^-8μg/mL. The immunosensor could be reused more than 10 times when renewed by HCl-Glycine buffer solution (pH 2.6).

Abstract: In this work, polyaniline nanofiber was synthesized. Then, polyaniline nanofiber and chitosan were dropped onto the surface of the self-prepared screen-printed electrode (SPE), respectively. After aminopyrene-BSA conjugate was immobilized on the modified electrode surface with the aid of EDC/NHS solution, the primary antibody was dropped on the modified SPE and followed by the HRP-labeled secondary antibody, thus a disposable immunosensor was developed for the rapid detection of benzo[a]pyrene based on an indirect immunoassay.

Abstract: A novel immunosensor based on porous silicon (PSi) for antigen detection was reported in this paper. The antigen (SpaA) and the specificity of the antibodies are employed as the target and the probe in our laboratory, respectively. The immunosensor structure was prepared using bioconjungation. After the antigen-antibody reaction, the red shift of the reflection spectrum of the immunosensor increases in proportion to the concentration of SpaA. The sensitivity of this immunosensor is 41nm/ µg•ml-1 and the detection limit is 2.44×102pg•ml-1, they are better compared with our previous work by using this method. Controlled experiments were also presented with non-immune antibody and the results show that this immunosensor possesses high specificity.