Shape-Specific Gold Nanoparticles for Multiplex Biosensing Applications

The biosensing field faces a significant challenge in efficiently detecting multiple analytes in a single diagnostic sample in order to compete with other established multiplex molecular diagnostic technologies such as PCR and ELISA. In response, we have developed a colorimetric nanobiosensor based on multiple morphological forms of functionalized gold nanoparticles (AuNPs) for the simultaneous detection of the influenza virus and SARS-CoV-2 virus. Gold nanospheres (GNSp) were modified with oligonucleotides specific for the influenza A virus, while gold nanoshells (GNSh) were modified with oligonucleotides specific for the SARS-CoV-2 virus. In the presence of their respective targets, AuNPs remain stable due to DNA–DNA interactions; conversely, in the absence of targets, AuNPs aggregate. Consequently, the hybrid system exhibits an indigo color with the SARS-CoV-2 target, a blue color with the Influenza A target, and a purple color with both targets, visible to the naked eye. Analytical sensitivity was 100 nM, and no cross-reactivity was observed with potentially confounding pathogens. This approach holds great promise for the simultaneous identification of multiple pathogens in a rapid manner without the need for equipment or trained personnel.