We next explored the feasibility of conducting a visible light-mediated thiol-ene reaction in aqueous media using CzBN and CzIPN conjugates as photocatalysts (Figure ). To date, there are only a few examples of thiol-ene reactions carried out in aqueous media under visible light excitation. Employing similar conditions to those reported previously, we were pleased to find that the desired thiol-ene adduct could be efficiently synthesized from Ac-Cys-OH and allyl alcohol in aqueous media, using conjugates 3ya and 6ca as photocatalysts. In contrast, 4CzIPN exhibited significantly lower catalytic reactivity due to its limited solubility in water. We further examined the compatibility of this reaction with longer peptide sequences. Conjugate 6ca demonstrated superior catalytic activity compared to 3ya, as the latter led to increased oxidation of the peptides during the photocatalytic process. Consequently, 6ca was selected as the preferred photocatalyst for thiol-ene reactions involving longer peptides. This reaction showed good tolerance for a variety of unprotected side-chain residues, yielding the desired thiol-ene adduct 10b with high efficiency. Moreover, the reaction was not limited to allyl alcohol 9a; a biotin-containing alkene 9b can also be incorporated into peptides, yielding the thiol-ene product 10c and 10d. Figure . Application of CzBN-and CzIPN-peptide conjugates in the photo-mediated decarboxylative alkynylation and the thiol-ene reactions. Yields were determined based on the integration of HPLC-UV signals.