Biodetection based on fluorescence quenching and surface-enhanced fluorescence using noble metal nanoparticles

Fluorescence is popular in carbohydrate, protein, and DNA arrays; cell imaging; and single molecule detection because of its sensitivity. To achieve high sensitivity, fluorophores possessing high quantum yields are necessary. However, most analytes do not fluoresce strongly. In order to overcome this shortage, techniques based on fluorescence quenching and surface-enhanced fluorescence using novel metal materials have been applied. Fluorescence quenching and enhancements are both dependent on the distance of fluorophores from the metal surface; quenching usually occurs at a distance no greater than 50 Å while fluorescence enhancement commonly takes place at a distance between 70 and 100 Å. In addition to distance, the nature, size, and shape of metal materials are important parameters for fluorescence quenching and enhancement. With advanced nanotechnology, researchers have demonstrated techniques entailing fluorescence quenching and enhancement using novel metal nanomaterials for the sensitive analysis of proteins, DNA, and small solutes.