PVA-reinforced glutathione–Ag hydrogels and release of Ag nanoparticles and drugs by UV-triggered controllable disassembly

Glutathione–Ag (GSH–Ag) supramolecular hydrogels have almost no mechanical strength, and the disassembly of GSH–Ag complexes occurs very easily under UV irradiation. In this work, low molecular weight polyvinyl alcohol (PVA) was used to reinforce GSH–Ag gels. The phase transition temperature of GSH–Ag gels can be increased from 45 to 60 °C in the presence of only 0.8 wt% of PVA. Rheological studies indicated that the storage modulus of reinforced GSH–Ag gels was 6 times higher than that of unreinforced gels. SEM studies revealed that the macromolecular chains of PVA are intertwined with the GSH–Ag aggregates, leading to an increase of mechanical strength. The TEM studies and UV-vis spectra indicated that Ag+ within the GSH–Ag gels was in situ reduced to form Ag nanoparticles under UV irradiation. Meanwhile, gradual disassembly of GSH–Ag hydrogels can be induced through controlling the time of UV irradiation. Based on this feature, the controllable release of a loaded model drug (crystal violet) and Ag species can be realized from the reinforced GSH–Ag gels. The release media show a good inhibition effect on E. coli.