Polymeric Micelles Encapsulating a Small Molecule SO2 Fluorescent Probe Exhibiting Novel Analytical Performance and Enhanced Cellular Imaging Ability.

Because of the limited knowledge on the relationship between molecular structure and analytical performance, developing a small molecule fluorescent probe with desirable response properties is usually a laborious work. On the other hand, the application of small molecule fluorescent probe in biological samples is always limited due to the unwanted interaction between dyes and biomacromolecules. Polymer micelles, thanks to its unique core-shell structure, may have the potential to improve these situations. However, utilization of polymer micelles to improve these situations is rarely explored. Herein, we engineered the first micellar SO2 nanoprobe Nano-Cz by self-assembly of a carbazole-based SO2 small molecule probe and an amphiphilic copolymer (DSPE-mPEG2000). The optical and cell imaging experiments revealed that Nano-Cz can work in 100% aqueous environment and act as an effective mitochondrial-targeting ratio SO2 nanoprobe. Compared with the single small molecule probe, Nano-Cz showed extraordinary large dynamic response range (0-0.7 mM vs 0-50 µM), eliminated signal interference from DNA and superior cellular imaging performance. These results clearly show the ability of polymer micelles in modulating sensors' analytical performance and reducing the signal interference from the unwanted interaction between small molecule probe and biomacromolecule, indicating that polymer micelles encapsulating single small molecule probe can provide us an alternative strategy to explore sensors with various performance and promote the biological application of fluorescent sensors. In addition, we hope that more and more polymer micelles would be used to construct biosensors in the future.