Abstract
Localized surface plasmons in metallic structures can sensitively detect biomolecules and has very high potentials in the biomedical applications. In this text, we introduce our research of using silver nanostructures to enhance the detection of fluorescent molecules. Different shapes of structures were studied by the dark-field optical microscopy. Comparing to the triangular and rectangular structures, the rod-like structure has the best effect in the fluorescence enhancement. In addition, the localized plasmons generate an optical trap that can increase the immobilization of nano-objects. Using the theoretical simulations and the optical microscopy, we verified the trapping effect of gold nanoparticles in the metallic nanoholes.