A gentle palette of plasma membrane dyes

Abstract

Plasma membrane stains are one of the most important organelle markers for unambiguous assignments of individual cells and monitoring membrane morphology and dynamics. The state-of-the-art PM stains are bright, specific, fluorogenic, and compatible with super-resolution imaging. However, when recording membrane dynamics, particularly under light-intensive microscopes, PM is prone to photodynamic damages due to its phospholipid bilayer nature. Here we developed PK Mem dyes tailored for time-lapse fluorescence imaging. By integrating triplet-state quenchers into the MemBright dyes featuring cyanine chromophores and amphiphilic zwitterion anchors, PK Mem dyes exhibited a three-fold reduction in phototoxicity and a more than four-fold improvement in photostability in imaging experiments. These dyes enable 2D and 3D imaging of live or fixed cancer cell lines and a wide range of primary cells, at the same time pair well with various fluorescent markers. PK Mem dyes can be applied to neuronal imaging in brain slices and in vivo two-photon imaging. The gentle nature of PK Mem palette enables ultralong-term recording of cell migration and cardiomyocyte beating. Notably, PK Mem dyes are optically compatible with STED/SIM imaging, which can handily upgrade the routine of time-lapse neuronal imaging, such as growth cone tracking and mitochondrial transportations, into nanoscopic resolutions.