The results reveal that the pCY‐pairs in the nanoplatform are quickly identified and cleaved by the overactivated caspase‐3 after sufficient transfection into YFP‐DEVD motifs‐CFP, resulting in diagnosis “ON” and the separation of CFP and YFP, thus enabling precise and real‐time diagnosis during injury and progressive phases of PF. The gene discussed is CFP; the disease is pemphigus foliaceus.