Abstract
Immunosensors based on impedance spectroscopy for diagnosing hepatitis C are reported where the sensing units were made with the antigenic peptide PPLLESWKDPDYVPPWHG (NS5A-1) derived from the NS5A protein of the hepatitis C virus (HCV) immobilized in layer-by-layer (LbL) films with silk fibroin (SF) and deposited on gold interdigitated electrodes. The electrical response of the sensing units varied upon immersion into solutions containing the antibody anti-HCV owing to the biomolecular recognition of NS5A-1. This was associated with morphological changes on the LbL films caused by adsorption of NS5A-1 and inferred from atomic force microscopy images. Buffer solutions with different anti-HCV concentrations down to 2 ng mL-1 could be clearly distinguished by analyzing the impedance spectroscopy data with a multidimensional projection technique. The specificity toward anti-HCV antibodies was confirmed in control experiments where no significant changes in the electrical response were measured by exposing the sensing units to solutions containing an anti-human immunodeficiency virus (HIV) antibody. The high sensitivity and selectivity of the units made with LbL films demonstrate the feasibility of measuring electrical impedance as an immunosensing strategy to detect hepatitis C.
Highlights
We report on electrical impedance measurements for detecting the anti-hepatitis C virus (HCV) antibody, again exploiting the biorecognition between the antibody and the antigenic peptide NS5A-1 immobilized in LbL films with silk fibroin (SF)
Impedance spectroscopy measurements were performed with 1-bilayer SF/NS5A-1 LbL films deposited onto interdigitated gold electrodes in the presence and absence of anti-HCV and anti-human immunodeficiency virus (HIV) antibodies
Using an information visualization technique, the multidimensional projection interactive document map (IDMAP) method, to treat the electrical impedance data obtained with a sensing unit containing an LbL film made with NS5A-1 peptide, we showed that distinct concentrations of antiHCV antibodies can be clearly identified
Summary
Hepatitis C virus (HCV) transmitted by contaminated blood or derivatives through transfusion or intravenous drug injections was identified in 1989.1 Its infection causes hepatitis C, a chronic infection leading to liver fibrosis, cirrhosis and even hepatocellular carcinoma, which affects ca. 200 million people worldwide.[2,3] Because transmission occurs in routine procedures such as blood transfusion, it is crucial to detect HCV with fast, low cost methods.[4,5] the tests for diagnostics most used today for hepatitis C, including enzyme-linked immunosorbent assay (ELISA), recombinant immunoblot assay and ribonucleicRecently, nanoarchitectonics has been applied in many research fields such as nano/molecular-scale control, fabrication and synthesis of nanostructured materials, in sensors and biological/biomedical applications.[9,10] Nanoarchitectonics is a new concept for the fabrication of functional material systems through harmonization of various actions including atomic/ molecular-level manipulation, chemical reactions, self‐assembly and self-organization and their modulation by external fields/stimuli.[11,12] From that concept, major efforts are devoted to develop novel HCV diagnostic methods,[13,14,15,16] especially employing electrochemical immunosensors. Impedance spectroscopy measurements were performed with 1-bilayer SF/NS5A-1 LbL films deposited onto interdigitated gold electrodes in the presence and absence of anti-HCV and anti-HIV antibodies.
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