Preparation and Investigation of Silver Nanoparticle⁻Antibody Bioconjugates for Electrochemical Immunoassay of Tick-Borne Encephalitis.

Yekaterina Khristunova,Vlastimil Vyskocil,Elena Dorozhko,Evgenii Plotnikov,Bohumil Kratochvil,Jiri Barek,Olesya Voronova,Vladimir Sidelnikov,Elena Korotkova

doi:10.3390/s19092103

Abstract

A new simple electrochemical immunosensor approach for the determination of antibodies to tick-borne encephalitis virus (TBEV) in immunological products was developed and tested. The assay is performed by detecting the silver reduction signal in the bioconjugates with antibodies (Ab@AgNP). Here, signal is read by cathodic linear sweep voltammetry (CLSV) through the detection of silver chloride reduction on a gold–carbon composite electrode (GCCE). Covalent immobilization of the antigen on the electrode surface was performed after thiolation and glutarization of the GCCE. Specific attention has been paid to the selection of conditions for stabilizing both the silver nanoparticles and their Ab@AgNP. A simple flocculation test with NaCl was used to select the concentration of antibodies, and the additional stabilizer bovine serum albumin (BSA) was used for Ab@AgNP preparation. The antibodies to TBEV were quantified in the range from 50 IU·mL−1 to 1600 IU·mL−1, with a detection limit of 50 IU·mL−1. The coefficient of determination (r2) is 0.989. The electrochemical immunosensor was successfully applied to check the quality of immunological products containing IgG antibodies to TBEV. The present work paves the path for a novel method for monitoring TBEV in biological fluids.

Highlights

Tick-borne encephalitis virus (TBEV) is one of the endemic flaviviruses in Russia, which can cause serious infections in humans that may result in encephalitis/meningoencephalitis
In the UV/Vis absorption spectra (Figure 2b), the maximum absorption of Ag NPs is in the range of 395–400 nm, which is in accordance with the average Ag NP size of 5.3 ± 1.2 nm calculated from the Transmission electron microscopy (TEM) observations (Figure 2a) [14]
This study has shown that the obtained silver-labelled Ab@AgNP bioconjugates can be used in voltammetric immunoassays to determine antibodies to tick-borne encephalitis virus (TBEV)

Summary

Introduction

Tick-borne encephalitis virus (TBEV) is one of the endemic flaviviruses in Russia, which can cause serious infections in humans that may result in encephalitis/meningoencephalitis. After TBEV infection, specific cellular and humoral responses are developed, and as a result, the production of antibodies to this pathogen starts. The most frequently used protective treatment for tick-borne encephalitis (TBE) within 96 h after a tick bite is the usage of the immunoglobulins against TBEV (passive immunization) [3,4]. It is important to monitor immunological products containing antibodies to TBEV that are used as post-exposure prophylaxis after a tick bite. For the successful diagnosis of TBE, detection of antibodies to this pathogen in human blood can be preferably used. Each ELISA kit includes a conjugate based on antibodies and marker enzymes. The significant loss of enzyme and immunoglobulins activity is possible (from 30 to 50%) in the process of their covalent crosslinking

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Results

Conclusion