Photoswitchable Biocompatible Polymer Dots Doped with Diarylethene

Abstract

Molecular photoswitches can be employed for the study of protein trafficking in living cells and applications in optical memories. Especially, to switch fluorescence, fluorescence quenching mechanism via energy or electron transfer is one of the most fundamental pathways to realize the system of photoswitching. In order to achieve fluorescence photoswitching, photochromic compounds such as diarylethene have been used to toggle fluorescence on and off. For example, photochromic diaryethene induces absorption changes upon light irradiations via cyclization reaction, which would trigger the fluorescence toggling. On the other hand, polymer dots (P-dots) is one of the promising fluorescent probes for the biological applications. We assumed that doping diarylethene into P-dots would realize fabrication of photoswhitchable P-dots via energy transfer mechanism between fluorescent polymer and diarylethene. In this study, we synthesized photoswitchable P-dots doped with diarylethene to toggle the fluorescence back and forth via energy transfer mechanism. We also tried to apply synthesized photoswitchable P-dots toward biological imaging. First, we examined the photoswitching properties with absorption and fluorescence measurements. Fluorescence of P-dots was dramatically quenched upon photoirradiation with UV light and recovered after visible light irradiation. Those photoswitching processes were reversible and could go through at least 5 cycles. We are now applying photoswitchable P-dots synthesized as mentioned above to biological imaging. Details will be discussed at the meeting.