Electrical Immunosensor Made with Antigenic Peptide NS5A‑1 Immobilized onto Silk Fibroin for Diagnosing Hepatitis C

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.

Nano‐bio‐engineered silk matrix based devices for molecular bioanalysis

“…The virus is usually transmitted through exposure to the blood (transfusion or infected needles) of an infected individual (Alter, 2007). This brings the need for an effective, low‐cost sensor for the diagnosis of Hepatitis C. A biosensor, based on impedance spectroscopy, was fabricated by Lima et al (2018), which used antibody–antigen interaction for the detection of HCV, as demonstrated in Figure 6A. A specific antigenic peptide NS5A‐1 (from the NS5A protein) was immobilized in an SF film using the layer‐by‐layer (LbL) method.…”

“…Therefore, the analyte used for the detection of the virus was antibody anti‐NS5A‐1 which is specific to the NS5A protein. This led to the development of a biosensor with high specificity and sensitivity that could detect anti‐HCV antibody concentration as low as 2 ng ml −1 with a linear detection range of 0−0.2 and 0−0.02 μg ml −1 for 1 and 5‐bilayer LbL films, respectively (Lima et al, 2018). In another similar attempt for the detection of HCV, luminescent YVO 4 :Eu 3+ nanoparticles were constructed by Lima et al (2016).…”

“… (A) Schematic representation of (a) NS5A‐1 immobilized 1‐bilayer SF LbL film fabrication and (b) specific recognition shown by NS5A‐1 for anti‐HCV. Source : Reproduced with permission from Lima et al (2018). (B) Schematic representation of blood typing through elution in silk thread containing antibodies.…”

Silk: history, obtaining, structure and properties of an old material in the development of new technologies

“…16,75 In this regard, fibroin has been extensively studied and stands out against other materials thanks to its unique properties, which include being mechanically robust 1,14,74 and transparent throughout the visible spectrum, presenting smooth surface and variable refractive index, [81][82][83] and being susceptible to physical changes in its structure. 76,77 All these characteristics allow the preparation of passive or active devices 75 based on pure fibroin 16 or fibroin in the presence of other components, 167 to provide materials like supports for electrodes, 16,221 lasers, [168][169][170][171][172][173][174] biosensors, [175][176][177][178][179][180] waveguide, 83,181,182 fuel cells, 183 and energy storage devices. 184 Kim and collaborators built an electrode consisting of a chip supported on an ultrathin and resorbable fibroin substrate.…”

Dielectric Permittivity and Surface Charge Density in Layer-by-Layer Poly(diallyldimethylammonium chloride)/Poly(styrenesulfonate) Nanostructured Films: Implications for Biosensing

“…The evaluation of the dielectric constant of the nanostructured films allows the appropriate choice of materials that best suits a specific application. Besides, evaluating the charge density in the outermost layer of the film supports choosing molecules that maximize the adsorption of the active layer in biosensing, potentially increasing their sensitivity. − …”