Localized surface plasmon resonance-based hybrid Au-Ag nanoparticles for detection of Staphylococcus aureus enterotoxin

Abstract The hybrid Au–Ag triangular nanoparticles were proposed for the purpose of biosensing. To construct the nanoparticles, an Au thin film was deposited on top of the Ag nanoparticles supported with glass substrate. The hybrid nanoparticles can prevent oxidation of the pure Ag nano-particles due to the Au protective layer caped on the Ag nanoparticles. The hybrid nanoparticles were designed using finite-difference and time-domain algorithm. Extinc-tion spectra of the hybrid nanoparticles excited by visible light beam with plane wave were calculated, and the corresponding electric fields at peak position of the extinction spectra were expressed also. It is clear that the hybrid nanoparticles can excite the localized surface plasmon resonance wave which can be used to detect biomolecules. As an application example, we presented relevant detection results by means of using protein A to covalently link surface of the hybrid nanoparticles. Refrac-tive index sensitivity of the hybrid nanoparticles was derived through both computational numerical calculation and experimental detection. Both the calculated and the experimental extinction spectra show that the hybrid Au– Ag nanoparticles are useful for detecting the biomolecules