Electro-Nano Diagnostic Platform Based on Antibody-Antigen Interaction: An Electrochemical Immunosensor for Influenza A Virus Detection.

H1N1 is a kind of influenza A virus that causes serious health issues throughout the world. Its symptoms are more serious than seasonal flu and can sometimes be lethal. For this reason, rapid, accurate, and effective diagnostic tests are needed. In this study, an electrochemical immunosensor for the sensitive, selective, and practical detection of the H1N1 virus was developed. The sensor platform included multi-walled carbon nanotube gold-platinum (MWCNT-Au-Pt) hybrid nanomaterial and anti-hemagglutinin (anti-H1) monoclonal antibody. For the construction of this biosensor, a gold screen-printed electrode (AuSPE) was used as a transducer. Firstly, AuSPE was modified with MWCNT-Au-Pt hybrid nanomaterial via drop casting. Anti-H1 antibody was immobilized onto the electrode surface after the modification process with cysteamine was applied. Then, the effect of the interaction time with cysteamine for surface modification was investigated. Following that, the experimental parameters, such as the amount of hybrid nanomaterial and the concentration of anti-H1 were optimized. Under the optimized conditions, the analytical characteristics of the developed electrochemical immunosensor were investigated for the H1N1 virus by using electrochemical impedance spectroscopy. As a result, a linear range was obtained between 2.5-25.0 µg/mL with a limit of the detection value of 3.54 µg/mL. The relative standard deviation value for 20 µg/mL of the H1N1 virus was also calculated and found as 0.45% (n = 3). In order to determine the selectivity of the developed anti-H1-based electrochemical influenza A immunosensor, the response of this system towards the H3N2 virus was investigated. The matrix effect was also investigated by using synthetic saliva supplemented with H1N1 virus.

Development and application of a SARS-CoV-2 colorimetric biosensor based on the peroxidase-mimic activity of γ-Fe2O3 nanoparticles.

A practical colorimetric assay was developed for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For this purpose, magnetic γ Fe2O3 nanoparticles were synthesized and used as a peroxidase-like mimic activity molecule. In the presence of γ Fe2O3 nanoparticles, the color change of H2O2 included 3,3',5,5'-tetramethylbenzidine was monitored at the wavelength of 654 nm when spike protein interacted with angiotensin-converting enzyme 2 receptor. This oxidation-reduction reaction was examined both spectroscopically and by using electrochemical techniques. The experimental parameters were optimized and the analytical characteristics investigated. The developed assay was applied to real SARS-CoV-2 samples, and very good results that were in accordance with the real time polymerase chain reaction were obtained.

Development of a Sandwich Immunosensor for concurrent detection of carcinoembryonic antigen (CEA), vascular endothelial growth factor (VEGF) and α-fetoprotein (AFP) biomarkers.

Cancer Biomarkers are important biological molecules which provide early detection, diagnosis and classification of cancer cells. In this work, nanoparticle tags with different redox potentials have been used as an electrochemical coding technology for the simultaneous detection of carcinoembryonic antigen (CEA), vascular endothelial growth factor (VEGF) and α-fetoprotein (AFP) biomarkers. As far as we know, this is the only work that covers the simultaneous detections of these biomarkers. For this purpose, basically, an electrochemical sandwich immunosensor, which was fabricated from carbon screen printed electrode, was utilized as a diagnostic platform. As nanoparticle tags, PbAu@É£Fe2O3, CuAu@É£Fe2O3 and ZnAu@É£Fe2O3 hybrid nanolabels were synthesized and used for labelling anti-CEA, anti-VEGF and anti-AFP, respectively. By monitoring differential pulse voltammetric oxidation peaks of labeling metals (Pb, Cu, Zn), CEA, VEGF and AFP biomarkers were detected at the same time.