Design of Chemically Induced Dimerization-based Amplifiable Probes (CIDAP). (A) LgBiT or SmBiT are fused to androgen receptor (AR) and transiently co-expressed in mammalian cells. Addition of androgens (such as DHT) triggers AR dimerization and the reconstitution of LgBiT and SmBiT to form nLuc. DHT can be converted to a prodrug (i.e., the probe), which reacts with redox signaling molecules (such as H2O2) to regenerate DHT. (B) The structures of DHT, CIDAP, CIDAP-NC1, and CIDAP-NC2. (C) The reaction mechanism of CIDAP and its cascade to release DHT. CIDAP-NC1 is the negative control that cannot regenerate DHT. CIDAP-NC2 is used as the control to investigate the impact of enzymatic hydrolysis on carbonate.