Erasable FAP Targeted Spray‐On Probe for Fluorescence‐Guided Surgery

Fluorescence-guided surgery is an emerging clinical field that aims to improve cancer detection in real-time, enabling spot-on therapeutic decisions. The use of fluorescent affinity probes has primarily involved systemically injected probes and, more recently, "spray-on probes". A current challenge has been to develop "turn-off" probes that can be inactivated by a UV light pulse and reduce background noise during iterative decision-making. Here, we report on the first development of a FAP-targeted erasable spray-on probe (ESOP). The probe consists of three components: (i) a highly bright, yellow light-emitting rhodamine dye, (ii) a photo-responsive linear triazene linker, and (iii) a FAP affinity ligand. We demonstrate that this probe could enable highly sensitive tumor-specific margin visualization within minutes after a spray-on application. Moreover, we show that the fluorescent signals could be fully erased with a 2-min UV-light pulse in tissue, permitting iterative staining applications with consistently high tumor-to-background ratios (TBRs). ESOP targeted against cancer or host tissue is feasible and is likely to yield transformative impacts on next-generation cancer surgeries, ultimately improving patient care.