An ultrasensitive electrochemical immunosensor for hepatitis C antibodies based on one-step-eletrosynthetized polypyrrole–graphene nanocomposite

Abstract

An ultrasensitive label-free electrochemical immunosensor was developed for hepatitis C antibodies (anti-HCV). Worldwide, it is estimated 71 million people have HCV infection in a chronic stage that may lead to cirrose and cancer. To achieve HCV elimination, health programs should include screening testing based on anti-HCV detection allowing the early-stage treatment. The immunosensor was based on a graphene oxide-polypyrrole (PPy–GO) film one-step electropolymerized on the electrode surface. Ultrasensitive anti-HCV detection was ensured by HCV antigen conjugated to biotin that was immobilized in a great amount on streptavidin-coated nanostructured surface. Analytical responses were obtained by anodic peaks from the square wave voltammetry in the presence of ferrocyanide/ferricyanide as a redox probe. This immunosensor exhibited a linear range from 2 to 14 ng mL −1 of anti-HCV and a limit of detection in the clinical range (1.63 ng mL −1 ). Furthermore, the immunosensor presented an efficient performance for the determination of anti-HCV in spiked serum samples, becoming this developed nanosensor as potential tools for early HCV diagnosis and screening. Supplementary Information The online version contains supplementary material available at 10.1007/s10853-022-06992-5.

A Redox-Probe-Free Immunosensor Based on Electrocatalytic Prussian Blue Nanostructured Film One-Step-Prepared for Zika Virus Diagnosis

“…This increase in the electroactive area of the CNT–CHI/PB was determined by CVs according to the Randles–Sevcik equation: Ip = (2.687 × 10 5 ) n (3/2) A·C o (D·ν) (1/2) where Ip is the current peak, n is the number of electrons transferred, A is the electrode area (cm 2 ), C o is the molar concentration of the redox species (mol·cm −3 ), D is the diffusion coefficient of PB, and ν is the scan rate (V·s −1 ). According to Equation (1), the current peak is directly proportional to the concentration, and its increase is related to the scan rate [ 37 , 38 ]. Conversely, the CNT–PB film without the presence of CHI did not produce peaks.…”

“…The immobilization of anti-Env ZIKV antibodies was confirmed by the reduction in the anodic peaks due to the insulating nature of the proteins (curve c) [ 42 ]. Given the cationic characteristics of CHI, anti-Env ZIKV antibodies were probably immobilized in an oriented mode, e.g., by their FC portion [ 38 ]. To block the nonspecific bindings, one aliquot (2 μL −1 ) of 100 molL −1 glycine solution was prepared in 100 mmol·L −1 Tris-HCl buffer (pH 6.5), pipetted onto the sensor surface, and left to react for 2 h. This step was important to avoid nonspecific bindings, which were confirmed by a decrease in the current redox peaks (curve d).…”

A Polypyrrole/Nanoclay Hybrid Film for Ultra-Sensitive Cardiac Troponin T Electrochemical Immunosensor

“…The electropolymerization of the COOH-Py on the GCE was performed by using cyclic voltammetry (CV) from −0.10 to 1.0 V at 200 mV s −1 for 20 successive cycles in acetonitrile containing 0.1 mol L −1 LiClO 4 [ 27 ]. The carboxylic groups of the polypyrrole film were activated with EDC (2.0 mmol L −1 ) and NHS (5.0 mmol L −1 ) solutions prepared in deionized water for 60 min at room temperature.…”