Antibacterial and cytotoxicity assessment of poly (N-vinyl imidazole)/nitrogen-doped graphene quantum dot nanocomposite hydrogels

Two series of pH-sensitive poly (N-vinyl imidazole)/nitrogen-doped graphene quantum dots nanocomposite hydrogels (PVI/NGQD) were synthesized successfully via an in situ polymerization approach. The polymerization was carried out with different feeding ratios of N-vinyl imidazole (0.75-2.00 mol/L), MBA (N,N '- methylene-bis-acrylamide) (0.02-0.18 mol/L) or DIL (3,3 ' -divinyl-1,1 ' (1,6-hexanediyl) di-imidazolium dibromide) (0.05-0.08 mol/L) as a crosslinker in the presence of NGQD nanoparticles (0.3-1.0 wt%) at 70 degrees C for 7 h. The pH-dependent swelling behavior was improved for DIL-based PVI/NGQD by increasing the contents of VI and NGQDs, while an increase in crosslinker value led to a reduced swelling degree. XRD and TGA results showed that the incorporation of NGQDs in hydrogel networks could increase the crystallinity and thermal stability of resultant PVI/NGQD nanocomposite. SEM images showed clear changes in surface morphology after incorporation of the NGQDs within the PVI hydrogel matrix, resulting in more porous network channels. Mechanical examinations indicated that MBA-based PVI/NGQD has higher compressive stress and Young's modulus, which improves with increasing NGQDs content due to increase in crosslinking density of nanocomposite. Therefore, MBA-based hydrogels become stiffer and more brittle than less-strength elastic DIL-based hydrogels. The prepared PVI/NGQD nanocomposite exhibited significant antibacterial activity against Gram-negative bacteria. In addition, the results showed that NGQDs and ionic DIL crosslinker have improved the antibacterial activity of PVI/NGQD hydrogels and decreased the degradation process. Finally, cell proliferation and cytotoxicity studies represented that these nanocomposite hydrogels can be considered as a potential candidate for biomedical applications.

Automated summary

Two series of pH-sensitive poly (N-vinyl imidazole)/nitrogen-doped graphene quantum dots nanocomposite hydrogels (PVI/NGQD) were successfully synthesized via in situ polymerization method. The swelling behavior of the hydrogels was influenced by the crosslinker and NGQD content, and the incorporation of NGQDs increased the crystallinity and thermal stability of the nanocomposites. The nanocomposite hydrogels exhibited antibacterial activity and potential for biomedical applications.