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

Abstract

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.

Poly(vinyl alcohol)–Carbon Nanodots Fluorescent Hydrogel with Superior Mechanical Properties and Sensitive to Detection of Iron(III) Ions

“…After the PVA solution was mixed with the CNDs, many PVA chains were adsorbed on the surface of the CNDs due to the strong hydrogen bonding, which was beneficial to the formation of the PVA tight network and improved the mechanical properties of the PVA‐CNDs hydrogel. And the CNDs also acted as a lubricant, thereby increasing the ductility of the PVA‐CNDs hydrogel . As shown in Figure , when the content of CNDs was 7.5% (PVA‐CNDs(III)), the compressive strength and ductility decreased.…”

“…The H‐bonds between CNDs weak compared to the H‐bonds between the PVA chains. When large number of CNDs were present in the hydrogel, they were more likely to aggregate and damage the H‐bonds between the PVA chains . We speculated that the decline in the mechanical properties of PVA‐CNDs hydrogels was mainly due to these reasons.…”

“…Poly(vinyl alcohol) (PVA) is an ideal biomaterial due to its low water absorption, excellent mechanical performances, and good biocompatibilities . Zhang et al found that PVA hydrogels prepared by freeze–thaw method can autonomously self‐healing at 25 °C by hydrogen bonding between PVA chains .…”

“…Zhang et al found that PVA hydrogels prepared by freeze–thaw method can autonomously self‐healing at 25 °C by hydrogen bonding between PVA chains . However, when the water content of hydrogels is more than 75 wt%, the hydrogel, obtained by the freezing/thawing method, cannot maintain strong mechanical performances, which limits the application of PVA hydrogel to some extent . The appearance of nanomaterials can further reinforce the mechanical properties of hydrogels and even provide various functions for hydrogels, such as antibacterial properties, photocatalytic activity, stimulating reaction behavior, and the like .…”

“…More importantly, the surface of CNDs have plenty of functional groups (such as graphene oxide), which can also form a strong interaction with the PVA chain, thereby improving the mechanical properties of the PVA hydrogel. Compared to other nanomaterials (GO), small‐sized CNDs can also be used as nucleating agents in PVA hydrogels to enhance their mechanical properties . The new functionality and properties for hydrogel are endowed by incorporating CNDs into PVA hydrogel, thereby expanding the range of applications for PVA hydrogels, such as fluorescence sensors.…”