A composite prepared from carboxymethyl chitosan and aptamer-modified gold nanoparticles for the colorimetric determination of Salmonella typhimurium

An aptamer-based assay is described for the determination of Salmonella typhimurium (S. typh). Carboxymethyl chitosan was loaded with amino-modified aptamer against S. typh, and then adsorbed on gold nanoparticles by electrostatic interaction to form a composite that acts as the molecular recognition element. In the presence of S. typh, it will be bound by the aptamer, and this changes the structure of the recognition element. On addition of...