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Abstract
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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 °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
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