Synthesis and characterization of chitosan-ZnO composite and its antibiofilm activity against aquatic bacteria

In the present study, chitosan-ZnO composite was synthesized by stirring of chitosan purified from mud crab Scylla serrata shells with zinc chloride and sodium hydroxide. The physicochemical characteristics of chitosan-ZnO composite were studied using UV-Vis spec, Fourier transform infrared, X-ray diffraction and scanning electron microscopy. Chitosan-ZnO composite formation was confirmed by the functional groups stretching and bending vibrations in Fourier transform infrared. Scanning electron microscopy results showed the synthesized chitosan-ZnO composite was rod-like structure. X-ray diffraction results represent the hexagonal shape and crystalline size (30–60 nm) of zinc oxide in the chitosan-ZnO composite. Antibacterial activity of chitosan-ZnO composite demonstrated the effective growth control of a Gram-negative Vibrio parahaemolyticus and Gram-positive Bacillus lechiniformis bacteria isolated from aquatic environments. Light microscopy and confocal laser scanning microscopy also evidenced the antibiofilm activity of chitosan-ZnO composite against the V. parahaemolyticus and B. lechiniformis at the concentration of 40 and 60 µg/ml, respectively.