Nanometal particles have high-density surface plasmon polariton fields, and when a fluorophore is placed within these fields, the lone pair electrons of the fluorophore, which normally participate in the fluorescence self-quenching, are transferred to the surface plasmon field, resulting in artificial fluorescence enhancement. Therefore, nanometal particles can be used to improve the effectiveness of fluorophore mediated biosensor and bio imaging by amplifying the fluorescence signals from the fluorophore at target locations. We have tested the fluorescence enhancement by nano-gold particles both in optic-fiber based biosensing system and in molecular imaging of breast cancer. The level of enhancement was found to depend upon the metal type, size of the particle, quantum yield of a fluorophore, and, most importantly, the distance between the nanoparticle and the fluorophore. Various ways to control the distance between a fluorophore and an NMP are applied, depending on the application. For fiber-optic immuno-sensing, as an in-vitro application, a surfactant layer was added at a particular thickness on the NMP before mixed with fluorophores, and the concentrations of the fluorophores and NMPs in solution are adjusted. For tumor model imaging, as an in-vivo study, fluorophores were covalently linked onto NMPs via a spacer at an appropriate size to ensure these two entities were placed together at the tumor site. For bio-sensing system, the fluorescence signal from the fluorephore was enhanced by as much as 200% with nano gold particles. In bio-imaging, the fluorescence of nanoparticle-linked Indocyanine green was enhanced by 800 times. Authors acknowledge the partially financial support from National Science Foundation (BES-0330075) on biosensing study. The authors also thank the U.S. Army Medical Research and Materiel Command (DAMD17-03-1-0572) for partial financial support. The authors also Dr. Achilefu's group at Washington University, MO for supplying Cypate.

Extended Abstract Status: Not Uploaded