Multi-protein-triggered, aptamer-tethered auto-cycling proximity recorder in formalin-fixed paraffin-embedded tissues.

Unraveling tumor-associated membrane proteins' spatial proximity holds a significance for clinically relevant multiple biomarker detection. Herein, based on aptamer binding to target proteins in clinical formalin-fixed paraffin-embedded (FFPE) tissue samples, we developed aptamer-tethered auto-cycling proximity recording (APR) probes as a proof-of-concept methodology for biosensing membrane proteins' spatial proximity. This APR enables continuous and repetitive recording of spatial neighboring pairs of DNA probes in FFPE breast cancer tissue samples in situ, without altering the probes themselves. Finally, this aptamer-based auto-cycling proximity recorder is able to identify spatial proximity of three membrane proteins in FFPE breast cancer tissues. Our research establishes a foundation for proximity-driven biosensing platform and provides a perspective for exploration in aptamer-based bioimaging in clinical tissue samples.