Investigation of electrochemical properties of silver nanoparticles conjugated with antibodies to tick-borne encephalitis for development of electrochemical immunosensor

In the past decade, interest to electrochemical assays have grown for determination anti-bodies in clinical and biological samples, where instead of the enzyme label metal nanoparticle is used. Such types of electrochemical immunosensors represent an upcoming trend in analytical chemistry. In this work, the electrochemical behavior of silver nanoparticles conjugated with anti-bodies to tick-borne encephalitis virus at different stages of electrode modification is investigated. Silver nanoparticles were obtained by chemical reduction from silver nitrate. Passive adsorption was chosen as a strategy for binding silver nanoparticles to antibodies to tick-borne encephalitis virus. The optimal ratio of antibodies to tick-borne encephalitis virus (4.5 IU ml^-1) in a solution of silver nanoparticles [1 mmol l^-1 AgNO₃] was found experimentally. The development of an electro-chemical immunosensor was based on indirect, non-competitive format of enzyme-linked immuno-sorbent assay. The electrochemical situation on the electrode surface after modification steps was demonstrated by cyclic voltammetry using a standard redox pair [Fe(CN)₆]^3-/[Fe(CN)₆]^4-. Glassy carbon electrode with electrochemically deposited gold nanoparticles was used as a platform for immobilization of biological material. It has been established that after sensitization of the electrode with antigen, passivation of the surface occurs. The voltammetric signal was recorded through the detection of silver ions oxidation on unmodified glassy carbon electrode under the working condi-tions: scan rate 0.1 V s^-1, potential accumulation-0.8 V, accumulation time 60 s. Thus, this work paves the way for a new alternative method for monitoring antibodies to tick-borne encephalitis virus in biological fluids.