A near-infrared cationic fluorescent probe based on thieno[3,2-b]thiophene for RNA imaging and long-term cellular tracing

Gene expression and regulation in which RNA is an essential participant can be visualized by imaging RNA with fluorescent probes. However, most of the reported fluorescent probes for RNA have defects such as short emission wavelength, small Stokes shift, poor selectivity, low sensitivity, and poor membrane permeability. Herein, a NIR (710 nm) cationic fluorescent probe PCTP with D-pi-A structure and large Stokes shift (285 nm) using 9-phenyl-carbazole as an electron donor and pyridinium salt as an electron acceptor was designed and synthesized. Titration experiments and enzyme treatment experiments demonstrate that PCTP can differentiate RNA from DNA in solution and cells, the fluorescence intensity of PCTP increases by a maximum of 52.2 times after binding to RNA and the detection limit is 2.17 mu g/mL, showing high selectivity and sensitivity to RNA. Furthermore, with low cytotoxicity, good biocompatibility and high photostability, PCTP is able to trace 4T1 cell proliferation in vitro to 9 generations and trace 4T1 cell in mice for 22 days. The probe provides a potential tool for RNA imaging and long-term cellular tracing.

Automated summary

A NIR cationic fluorescent probe PCTP with D-pi-A structure and large Stokes shift was designed and synthesized, which can differentiate RNA from DNA with high selectivity and sensitivity. The probe shows potential applications in RNA imaging and long-term cellular tracing.