Two-photon absorbing fluorescent nanoparticle composites

ORGN 468

Sheng Yao, syao@mail.ucf.edu1, Kevin D. Belfield, belfield@mail.ucf.edu2, and Zhen-Li Huang, huangz@creol.ucf.edu2. (1) Department of Chemistry, University of Central Florida, 4000 Central Florida Boulevard, P.O. Box 162366, Orlando, FL 32816-2366, (2) Department of Chemistry and CREOL, College of Optics and Photonics, University of Central Florida, 4000 Central Florida Blvd., P.O. Box 162366, Orlando, FL 32816-2366
Fluorescent probes for two-photon fluorescence microscopy is a key for further application of this emerging technology for bioimaging. The recent effort to develop hydrophilic fluorophores with large two-photon absorptivities has focused on introduction of very polar substituents such as carboxylate or ammonium salts. However, this involves tedious synthetic and purification processes. On the other hand, the synthesis and purification of hydrophobic fluorophores are much easier and the chemistry is well established. Flourescent compounds with two-photon absorption (2PA) cross-sections as high as several thousand GM have been reported. In this work, a nanotechnological approach was employed to directly dope these hydrophobic 2PA materials into water-soluble nanoparticles to achieve the hydrophilicity. The nanoparticles may be inorganic silica based or organic based, and were characterized by TEM and fluorescence spectroscopy. The fluorescent nanoparticles were cell permeable and the two-photon fluorescent images of nanoparticle stained cells are presented.