A Study Of Biosensing Based On The Noble Metal Nanoparticles

Since nanoscale materials are on the same size scale as biological macromolecules, proteins and nucleic acids, and possess unusual optical, magnetic, electronic, catalytic, and mechanical properties, they have become the hot point in the research field of biological science. Noble metal nanoparticles such as gold and silver nanoparticles have an unusual property of absorption and scattering. Thus, a powerful mechanism of detecting important molecules in a variety of applications by using noble metal nanoparticles is emerging.In this paper, the current technology of fiber-optic biosening is introduced and analyzed. Moreover, the technology of fiber-optic biosening based on the noble metal nanoparticles is studied in detail. The localized surface plasmon resonance (LSPR) of noble metal nanoparticles is examined, and the discussion of its application in biosensing is followed. Based on the newly developed method, discrete dipole approximation (DDA), solutions of the Maxwell equations are obtained. The sensitivity of the metal nanoparticles on the size and shape is analyzed numerically.The results presented in this paper show that: (1) the extinction spectra of metal nanoparticles are very sensitive to the dielectric properties of the surrounding medium. As the refractive index of the surrounding medium increases, the extinction maximum of the nanoparticles red-shifts in wavelength. (2) There is an approximately linear relationship between theλmax of extinction and the refractive index of the external dielectric medium. Theλmax of extinction depends on both the size and the shape of the nanoparticles, but the influence of the shape is more significant. (3) Based on our simulation, the most sensitive nanoparticles can sense a 0.005 change in the refractive index of the external medium, resulting in a 1 nm shift in the extinction maximum of the surface plasmon resonance, with a sensitivity of 200nm/RIU.