Cooperative blinking from dye ensemble activated by energy transfer for super-resolution cellular imaging

Photoblinking is a fundamental process that occurs exclusively in single fluorophores such as organic dyes, fluorescent proteins, and quantum dots. Here, we describe a strategy to achieve pronounced, high on/off ratio, and cooperative blinking in donor-acceptor multifluorophore systems. An ensemble of dye molecules doped in semiconducting polymer dots (Pdots) exhibit robust photoblinking, while the pristine Pdots and the dye in optically inert polymer matrices fluoresce continuously. Energy transfer from Pdots to dye acceptors produces photoblinking via a cooperative process, in which the bright state originates from the dye ensemble and the dark state is due to quenching of semiconducting polymer by hole polarons. Using the blinking Pdots in subcellular structures labeling, we demonstrated approximately 3.6-fold enhancement of imaging resolution in high-order super-resolution optical fluctuation nanoscopy as compared to conventional microscopy. Our findings not only demonstrate the exciting possibility of transforming a nonquantized ensemble into a single-emitter-like optical source but also provide an effective approach to generate superior photoblinking fluorescent probes for super-resolution imaging applications.