Targeted Photoconvertible BODIPYs Based on Directed Photooxidation Induced Conversion for Applications in Photoconversion and Live Super Resolution Imaging

Abstract

Photomodulable fluorescent probes are drawing an increasing attention due to their applications in advanced bioimaging. Whereas photoconvertible probes can be advantageously used in tracking, photoswitchable probes constitute key tools for single molecule localization microscopy to perform super resolution imaging. Herein we shed light on a red and far-red BODIPY, namely BDP-576 and BDP-650 possessing both properties of conversion and switching. Our study demonstrates that theses pyrrolyl-BODIPYs respectively convert towards typical green- and red-emitting BODIPYs that are perfectly adapted to microscopy. We also showed that these pyrrolyl-BODIPYs undergo Directed Photooxidation Induced Conversion, a photoconversion mechanism that we recently introduced and where the pyrrole moiety plays a central role. These unique features were used to develop targeted photoconvertible probes towards different organelles or subcellular units (plasma membrane, mitochondria, nucleus, actin, Golgi apparatus, etc.) using chemical targeting moieties and Halo tag. We notably showed that BDP-650 could be used to track intracellular vesicles over more than 20 minutes in two color imaging with laser scanning confocal microscopy demonstrating its robustness. The switching properties of these photoconverters were studied at the single molecule level and were then successfully used in live Single Molecule Localization Microscopy in epithelial cells and neurons. Both membrane and mitochondria targeted probes could be used to decipher membrane 3D architecture and mitochondria dynamics at the nanoscale. This study builds a bridge between the photoconversion and photoswitching properties of probes undergoing directed photooxidation and shows the versatility and efficacy of this mechanism in live advanced imaging.