Fig. 4

Antibacterial activities of different concentrations of CuNA and GelMA composite hydrogels (a, b) The antibacterial rate of different concentrations of CuNA against E. coli and S. aureus after 24 and 48 h contact time. c The inhibition zone of different divalent ions cross-linked GelMA hydrogels against E. coli and S. aureus photographed by the digital camera after 48 h. d, e Antibacterial rate of different GelMA composites is represented by the inhibitory zone diameter. Scale bar is 10 mm. Data are expressed as mean ± SD (n = 3). (*p < 0.05, **<0.01, **<0.001 compared to the 3% CuNA@GelMA)