Electrodeposited Gold Nanoparticle (AuNP)-Film as a Nanoplatform for a Label-Free Electrochemical Strongyloidiasis Immunosensor

Abstract

Strongyloidiasis is an intestinal helminth infection caused by Strongyloides stercoralis. Early detection of this infection in immunocompromised patients is crucial to avoid severe complications and fatality. Herein, we present the potential application of electrodeposited AuNP-film in developing a label-free electrochemical immunosensor for strongyloidiasis using our synthesized monoclonal antibody. Layer-upon-layer attachment of Strongyloides monoclonal recombinant antibody protein (rMAb23) onto AuNP-film was constructed, utilizing a thiol linker via a self-assembly monolayer (SAM) technique. The modified electrode was utilized to detect S. stercoralis recombinant NIE (rNIE) protein. Each successful modification step was tested in a 10 mM [Fe(CN) ₆] ^3−/4− redox couple solution utilizing cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) techniques. The developed immunosensor required 20 min of incubation with an rNIE solution. Specificity study showed no cross-reaction with three other helminth recombinant proteins. Utilizing EIS measurements on a concentration series of rNIE protein in phosphate-buffered saline (PBS), ranging from 1 μg mL ⁻¹ to 10 μg mL ⁻¹, we obtained a detection limit (LOD) of 0.182 μg mL ⁻¹. The electrochemical immunosensor was also successfully used to analyze serum samples of individuals with strongyloidiasis and healthy people. The results indicated that the immunosensor might offer an excellent diagnostic capability and a rapid and sensitive antigen detection of strongyloidiasis.