PVA/Carbon Dot Nanocomposite Hydrogels for Simple Introduction of Ag Nanoparticles with Enhanced Antibacterial Activity

The introduction of nanomaterials to hydrogels is an effective way to improve the mechanical properties of hydrogels. Herein, carbon nanodot (C-dot) as a new-found excellent nanomaterial is first added to polyvinyl alcohol (PVA) hydrogel to prepare PVA/C-dot hydrogel by freeze-thaw method. The appropriate size and plenty of surface functional groups make C-dot an ideal nucleating agent for PVA crystallization, which leads to form a denser and more uniform cross-linked network in PVA hydrogel, and in turn enhance the mechanical properties of PVA hydrogel. Compared to pure PVA hydrogel, about a 46.4% increase of tensile strength and 18.5% increase of elongation at break are achieved when the content of C-dot in PVA/C-dot hydrogel is 2 wt%, suggesting that C-dot can effectively improve the mechanical properties of PVA hydrogel. Besides, C-dot can endow PVA hydrogel with some new properties, such as fluorescence and reducibility. Herein, Ag nanoparticles are simply introduced and uniformly dispersed in PVA hydrogels with the help of reducibility of C-dot, which can greatly enhance the antibacterial activity of PVA/C-dot hydrogels, and enlarge their application potential in medical field.