Polymersomes-mediated delivery of fluorescent probes for targeted and long-term imaging in live cell microscopy.

Fluorescent microscopy becomes an essential tool for live imaging analysis of complex biological pathways and events as it enables noninvasive real-time/real-space imaging. The design of fluorescent probes to provide dynamic information and long-term tracking of samples without altering physiological and structural integrity is critical in live imaging. In recent years, nanotechnology has produced a new generation of imaging probes with promising applications in live imaging. In particular, we describe the use of pH-sensitive amphiphilic block copolymer PMPC25-PDPA70. This polymer forms biomimetic nanometer-sized vesicles (known as polymersomes) that are readily uptaken by a wide variety of cell types. The pH sensitivity confers much needed endolysomal escape capability without inducing cellular toxicity or stress. Two different characteristic compartments in the polymersomes (hydrophilic core and hydrophobic membrane) allow for encapsulation of different labeling cargoes such as lipidic cell membrane probes, quantum dots, fluorescent dyes, and fluorescent biomolecules such as nucleic acid and protein probes.