CTSS and neoplasm: YBN14 entails the accommodation of the qABP and PDT dual platforms in a single chemical scaffold with the following advantages: (i) it works in tumor microenvironments with high cathepsin activities, (ii) it is used for real-time imaging of tumors before light sensitization, (iii) the quencher ensures diminished background fluorescence, and (iv) covalent binding prevents rapid clearance.