A Peptide-Based Iron Nanozyme with Multienzyme-Mimetic Activity for Sensitive Colorimetric Detection of Glutathione

Glutathione (GSH), a crucial intracellular antioxidant, plays a critical role in maintaining redox homeostasis and is closely implicated in the pathogenesis of numerous diseases, thereby necessitating sensitive, reliable, and convenient detection strategies. Inspired by natural nonheme iron enzymes, we designed an amphiphilic peptide, C₁₆-VVAAEE, which undergoes Fe³⁺-coordinated self-assembly into β-sheet-rich nanoribbon architectures, forming a peptide-based metal nanozyme (P6-Fe). Molecular dynamics simulations combined with spectroscopic characterizations confirmed the ordered β-sheet nanoribbon structure and effective metal-ligand coordination. Benefiting from its biomimetic catalytic center and hierarchical assembly, P6-Fe exhibits pronounced multienzyme-mimetic activities, with particularly strong peroxidase-like (POD) performance. Exploiting this catalytic activity, a sensitive and selective colorimetric platform for GSH detection was established, achieving a low detection limit of 1.26 μM. The sensor displays excellent selectivity against common interfering species, along with outstanding catalytic robustness over a wide range of pH values, temperatures, and prolonged storage periods. Furthermore, integration with a smartphone imaging platform enabled rapid and visual quantitative analysis. This work presents a facile, cost-effective, and user-friendly strategy for GSH sensing, while underscoring the considerable potential of peptide-based metal nanozymes for next-generation bioanalytical and diagnostic applications.