Microviscosity is a fundamental parameter in the biophysics of life science and governs numerous cellular processes. Thus, the development of real-time quantitative monitoring of microviscosity inside cells is important. The traditional probes for detecting microviscosity via time-resolved luminescence imaging (TRLI) are generally disturbed by autofluorescence or surrounding oxygen in cells. Herein, we developed loose packing nanoaggregates with aggregation-induced delayed fluorescence (FKP-POA and FKP-PTA) and free from the effect of oxygen and autofluorescence for viscosity mapping via TRLI. The feasibility of FKP-PTA nanoparticles (NPs) for microviscosity mapping through TRLI was demonstrated by monitoring the variation of microviscosity inside HepG2 cancer cells, which demonstrated a value change from 14.9 cP to 216.9 cP during the apoptosis. This indicates that FKP-PTA NP can be used as a probe for cellular microviscosity mapping to help people to understand the physiologically dynamic microenvironment. The present results are expected to promote the advancement of diagnostic and therapeutic methods to cope with related diseases.
Keywords: aggregation-induced delayed fluorescence; aggregation-induced emission; microviscosity probe; molecular motion; time-resolved imaging.