Fig. 3. AIE-based substrates for caspase 6. (A) Schematic representation of the activation of AIE-based protease substrates. The pentapeptide designed for caspase 6 was labeled with TPE fluorogen and treated with protease. After peptide bond hydrolysis, TPE tags are released and undergo spontaneous aggregation, yielding a strong fluorescence signal. (B) The synthesis route of TPE-N3 (TPE-azide) fluorogen. (C) Schematic representation of peptide-Lys-TPE synthesis. The caspase 6 peptide bearing alkyne-functionalized lysine (P1′ position) was synthesized and subsequently conjugated with the TPE-N3 moiety through click chemistry.
