Optical fiber affinity biosensor based on localized surface plasmon resonance

Abstract

A highly sensitive micrometer-sized optical fiber affinity biosensor is reported based on the localized surface plasmon resonance in gold nanoparticles adsorbed at an endface of an optical fiber. This sensor probes the affinity between biological molecules in real time without any labeling of the analyte. The highest resolution of ${10}^{-5}$ in refractive index units is demonstrated with a red-light-emitting diode used as a light source. This value corresponds to an adsorption amount of ${10}^{-12}\mathrm{g}∕{\mathrm{mm}}^2$ in the case of the affinity measurement. This sensitivity is similar to that of the conventional surface plasmon resonance biosensors that use attenuated total reflection optics.