A novel tool for capture and detection of typhoid fever using Ag-labeled nanocomposites.

This work investigated a simple and versatile modification to a solid substrate to develop antibody recognition using nanoparticles. The new immobilized metal ion affinity adsorbent containing nanoparticles and hydrophilic resins is proposed here to improve the binding of antigen on its surface. The light-scattering properties of submicroscopic metal particles ranging from 100 to 120 nm in diameter were confirmed by scanning electron microscopy. We found that synthesized nanoparticles have an inherent enzyme mimetic activity similar to that found in natural peroxidases. The synthesized nanoparticles were coated with Salmonella typhi and Salmonella paratyphi antigens and were allowed to react with Salmonella-infected serum. Positive reactions were detected visually with the naked eye. The color changes of substrate (TMB) were observed even in 1:800 dilutions. This report helps in developing a specific immunoassay using nano-conjugated antigen for the rapid detection of S. typhi and S. paratyphi antibodies in infected serum.