Abstract
Cutaneous squamous cell carcinoma (cSCC), the second most common skin cancer, requires early and accurate detection to optimize clinical management. Fluorescence imaging has emerged as a non-invasive and cost-effective tool with high sensitivity for tumor diagnosis; however, existing probes for cSCC are limited in achieving rapid and specific imaging. In this study, we introduce FC-1, a dual-tandem activatable fluorescent probe designed for precise cSCC diagnosis by simultaneously targeting fibroblast activation protein α and cathepsin C (CTSC). This dual-locked activation strategy effectively reduces nonspecific signals in normal tissues while enhancing diagnostic specificity. In vivo studies in SCC-7 xenografted mice demonstrated FC-1's ability to visualize subcutaneous tumors with high sensitivity and specificity. Moreover, FC-1 enabled clear differentiation between cSCC and keloids. The probe's dual-activation mechanism and robust performance underscore its potential as a clinically translatable tool for early cSCC detection and differential diagnosis.