Hydrogel-based C₃N₄@CDs-ZIF multienzyme-like nanozymes: Multi-band optical/piezoelectric multimodal catalysis

Inspired by the multienzyme-like cascade of natural antioxidative systems, we report a sustainable photoluminescent hydrogel platform (PAM:C₃N₄@CDs-ZIF) engineered with synergistic photo-/piezoelectric enhancement. By constructing an S-scheme heterojunction between carbon nitride (C₃N₄) nanosheets and carbon dot-functionalized ZIF-8 (CDs-ZIF) within a polyacrylamide matrix, the hydrogel integrates multiple enzyme-mimicking activities, including peroxidase (POD), oxidase (OXD), catalase (CAT), and superoxide dismutase (SOD). The catalytic activities are tunable and stimulus-enhanced under multi-wavelength photoexcitation (UV/Vis/NIR) and ultrasound-induced piezoelectric stimulation. Band-structure analysis, ultraviolet photoelectron spectroscopy (UPS), electron spin resonance (ESR) spectroscopy, and transient photocurrent response collectively support an S-scheme charge-transfer pathway, in which interfacial electric-field-assisted charge separation promotes reactive oxygen species generation and conversion. As a result, the hydrogel achieves 92.5% Rhodamine B degradation within 5 min under combined UV/ultrasound stimulation and exhibits 96.47% antibacterial efficiency against Staphylococcus aureus . In addition, an infected diabetic wound model demonstrates accelerated wound closure, suggesting the potential of this adaptive catalytic hydrogel for antibacterial tissue repair. This work provides a rational strategy for designing smart, energy-stimulated hydrogel nanozymes for environmental remediation and biomedical applications.