Circularly polarised luminescence laser scanning confocal microscopy to study live cell chiral molecular interactions

The molecular machinery of life is founded on chiral building blocks, but no experimental technique is currently available to distinguish or monitor chiral systems in live cell bio-imaging studies. Luminescent chiral molecules encode a unique optical fingerprint within emitted circularly polarized light (CPL) carrying information about the molecular environment, conformation, and binding state. Here, we present a CPL Laser Scanning Confocal Microscope (CPL-LSCM) capable of simultaneous chiroptical contrast based live-cell imaging of endogenous and engineered CPL-active cellular probes. Further, we demonstrate that CPL-active probes can be activated using two-photon excitation, with complete CPL spectrum recovery. The combination of these two milestone results empowers the multidisciplinary imaging community, allowing the study of chiral interactions on a sub-cellular level in a new (chiral) light. Here, the authors introduce a live-cell imaging system using chiroptical contrast, enabling the study of chiral interactions. They demonstrate simultaneous imaging of enantiomeric pairs of molecular probes emitting circularly polarised light, using both single and two-photon excitation.