Photostable fluorescent probes for 3D imaging and monitoring the metabolism of lipid droplets

In addition to being associated with energy supply, lipid droplets (LDs) play vital roles in many other important physiological and some pathological processes. Fluorescent probes are useful tools for studying the biological functions of LDs. In this study, we develop three new highly fluorescent LD-specific bioprobes, which can be excited by one- and two-photon, with favorable biocompatibility. They have little crosstalk with some commonly used commercially-available green- and red-emissive probes, such as BODIPY 493/503, MitoTracker Red CMXRos (MTR) and LysoTracker Red DND-99 (L111), thus allowing the simultaneous multicolor imaging. Notably, one of the probes, BIP-1, has superior photostability and allows excellent 3D imaging of cellular LDs. BIP-1 can be used to monitor the number and morphological changes of LDs, and the interactions of LDs with other organelles (e.g. mitochondria) under specific physiological conditions (e.g. starvation). Overall, BIP-1 is a promising alternative fluorescent bioprobe for live-cell LD-specific imaging and long-term tracking during LD-related research.