ZnO nanorod-chitosan composite coatings with enhanced antifouling properties

The current study describes the fabrication of chitosan‑zinc oxide nanorods composite (CHT/ZnO) on fiberglass panels (support substrate). ZnO nanorods (NRs) with size ranging from 20 to 100 nm and some microrods with an approximate size of 0.5–1 μm were grown on fiberglass panels. CHT 1%/ZnO composite had ZnO NRs incorporated into chitosan (CHT) coating while ZnO NRs were not visible in the CHT 2%/ZnO NRs composite. XRD and FTIR results showed the presence of the ZnO and chitosan. The water contact angle decreased from 80° ± 2° (control) to 65° ± 2° for CHT 1%/ZnO NRs and 42 ± 2° for CHT 2%/ZnO NRs composite coatings. The antimicrobial activities of the coated fiberglass panels were investigated using biofilm-forming bacteria Bacillus subtilis and Escherichia coli under both light and dark conditions. CHT/ZnO composite coated fiberglass panels showed the strongest antimicrobial activity compared to chitosan, ZnO NRs coatings, and Zn-based antifouling paint in the experiments with B. subtilis and E. coli under light conditions. The highest antifouling activity was observed for CHT 2%/ZnO composites. CHT/ZnO composites can be good alternatives to the toxic antifouling paints.