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Stimuli-responsive supramolecular gels and metallogels have been widely explored in the past decade, but the fabrication of metallogels with reversible photoresponsive properties remains largely unexplored. In this study, we report the construction of photoresponsive hybrid zinc-based metallohydrogel systems coassembled from an imidazole functionalized phenylalanine derivative gelator (ImF) and carboxylic acid functionalized arylazopyrazole (AzoPz) molecular photoswitches in the presence of Zn 2+ ions. Unlike traditional covalent conjugation, noncovalent introduction of small molecular switches into the gel matrix provides a convenient route to generate photoresponsive functional materials with tunable properties and expands the scope of optically controlled molecular self-assemblies. It has been found that the carboxylic acid functionalized AzoPz derivatives alone or mixed with the ImF moiety could not self-assemble to form any gels. However, in the presence of Zn 2+ ions they readily formed the coassembled hybrid metallogels in an alkaline aqueous solution with various morphologies. These results suggest that the gelation process was triggered by the Zn 2+ ions. In addition, the ImF gelator shows specific response to Zn 2+ ions only. The presence of the AzoPz moiety in the gel matrix makes the metallogel coassemblies photoresponsive and the reversible gel-to-sol phase transition was studied by UV-vis spectroscopy. The gels showed a slow reversible light-induced gel-to-sol phase transition under UV ( λ = 365 nm) and then sol-to-gel transition by green light ( λ = 530) irradiation resulting in the reformation of the original gel state. The morphology and viscoelastic properties of the fibrillar opaque metallogels have been characterized by transmission electron microscopy (TEM) and rheological measurement, respectively. 

Abstract Despite multiple new‐drug approvals in recent years, prostate cancer remains a global health challenge because of the prostate cancers are resistant to androgen deprivation therapy. Here, we show that a small D‐phosphopeptide undergoes prostatic acid phosphatase (PAP)‐instructed self‐assembly for inhibiting castration‐resistant prostate cancer (CRPC) cells. Specifically, the installation of phosphate at the C‐terminal of a D‐tripeptide results in the D‐phosphopeptide. Dephosphorylating the D‐phosphopeptide by PAP forms uniform nanofibers that inhibit VCaP, a CRPC cell. A non‐hydrolyzable phosphate analogue of the D‐phosphopeptide, which shares similar self‐assembling properties with the D‐phosphopeptide, confirms that PAP‐instructed assembly is critical for the inhibition of VCaP. This work, for the first time, demonstrates PAP‐instructed self‐assembly of peptides for selective inhibiting CRPC cells.