Photostable AIE Probes for Wash-Free, Ultrafast, and High-Quality Plasma Membrane Staining

Plasma membrane (PM), a fundamental building component of a cell, is responsible for a variety of cell functions and biological processes. However, it is still challenging to acquire its morphology and morphological variation information via an effective approach. Herein, we report a PM imaging study regarding an aggregation-induced emission luminogen (AIEgen) called tetraphenylethylene-naphthalimide+ (TPE-NIM+), which is derived from our previously reported tetraphenylethylene-naphthalimide (TPE-NIM). The designed AIEgen (TPE-NIM+) shows significant characteristics of ultrafast staining, high photostability, wash-free property, and long retention time at the PM, which can structurally be correlated with its positively charged quaternary amine and hydrophobic moiety. TPE-NIM+ is further applied for staining of different cell lines, proving its universal PM imaging capability. Most importantly, we demonstrate that TPE-NIM+ can clearly delineate the contours of densely packed living cells with high cytocompatibility. Therefore, TPE-NIM+ as a PM imaging reagent superior to currently available commercial PM dyes shall find a number of applications in the biological/biomedical fields and even beyond.