Infrared Emitting Dye and/or Two Photon Excitable Fluorescent Dye Encapsulated in Biodegradable Polymer Nanoparticles fo
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AA9.10.1
Infrared Emitting Dye and/or Two Photon Excitable Fluorescent Dye Encapsulated in Biodegradable Polymer Nanoparticles for Bioimaging
Koichi Baba, Tymish Y. Ohulchanskyy, Qingdong Zheng, Tzu-Chau Lin, Earl J. Bergey and Paras N. Prasad Department of Chemistry, Institute for Lasers, Photonics and Biophotonics, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA.
ABSTRACT
Near infrared fluorescent dyes have a significant potential in biological applications. However, many of these organic dyes are hydrophobic and/or their fluorescence is quenched in aqueous media. Nanoparticle technology has been utilized to overcome the hydrophobic property of these dyes, but there remain problems in their fabrication. To overcome these problems, a novel fabrication technique for incorporating hydrophobic dyes in a biodegradable polymer nanoparticle has been developed. An infrared emitting dye (D1) and a two photon excitable fluorescent dye (BT101) were selected as prototypic dyes for incorporation. The D1 nanocrystal dye shows quenched emission in aqueous media. Upon encapsulation in a polymeric nanoparticle, its emission at 1.1 to 1.35 µm was recovered. BT101 dye doped nanoparticles demonstrated significant increase in fluorescent yield in aqueous media as compared to the free dye. In addition, several different sizes of BT101 doped polymer nanoparticles were fabricated (c.a. 35 nm to 100 nm in size). The fluorescence intensity was found to increase with the particle size. The investigation of uptake of BT101 nanocrystal and BT101 doped PLGA nanoparticles by culture cells revealed the importance of polymer coating of dye for efficient cell imaging.
INTRODUCTION
Current technology in fluorescent imaging has advanced significantly allowing for multiprobe applications in the study of biological events. To further advance this fluorescent imaging capability, organic fluorophores absorbing and emitting in the near infrared are being developed [1]. These near infrared dyes have the advantage of providing a better signal to noise ratio due to reduction of UV or visible light generated autofluorescence. Secondly, tissue penetration is greater for near-infrared due to lower absorption of excitation light. However, many of these dyes have less than optimal solubility and emissions in aqueous systems, making many of them unsuitable for biological applications. The infrared emitting dye D1 (Fig. 1A) that our laboratory has synthesized, shows fluorescence around 1.1 to 1.35 µm in organic solvents, but is significantly quenched in aqueous media. Two photon excitable fluorescent dye BT101 (Fig. 1B), which was synthesized by our group, has a polar D-π-A structure, in which the π-system is end-capped by an electron donor (D) and an electron acceptor (A) [2]. This structure is one of the most effective molecular models for both second- and third-order nonlinear optical materials, thus BT101 has great potential to be
AA9.10.2
suitable for two-photon imaging. However, as with D1, BT101 lacks CH CH the nece
