Study Of Novel Antibacterial And Anti-mildew Coatings

The relationship between people’s health and living environment is very important. People are prone to be attacked by ubiquitous pathogenic microorganisms at any moment. In addition, conditions of living environment are influenced by mildewy paper and drygoods. Physical properties of paper, such as fold and tensile, will be influenced by mildewy paper. Also, drygoods will be destroyed by microbe. Since the harm of mildewy paper and drygoods for human being, it is significative which the novel antibacterial and anti-mildew coatings (AAC) are studied.Using chitosan and titanium dioxide (TiO2), the novel antibacterial and anti-mildew coatings and the following chitosan/TiO2complex film were prepared. The optimal amount of chitosan and TiO2in the AAC preparation was05%and0.25%, respectively. The characteristics of the chitosan/TiO2complex film were described by Fourier-transform infrared spectrometry (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and XPS spectra. After being combined of chitosan and TiO, the apparent optical bandgap (Eg) of chitosan/TiO2complex film was diminished, which induced the absorption spectrum of complex film red shifted to visible light. Red shifted showed that photocatalysis of complex film performed under visible light.The antibacterial and anti-mildew activities were studied. The results indicated that, the antimicrobial ratio of the AAC for E. coli, A. niger and C. albicans reached99.99%after1h under visible light irradiation; and the antimicrobial activity was evidently better than pristine chitosan and TiO2. Long-lasting antibacterial and anti-mildew activities were also showed; and antimicrobial ratio reached80%after4h was obtained after12months. The paper treated with the novel antibacterial and anti-mildew agent showed excellent anti-mildew activities, the antimicrobial ratios for A. niger could reach99.99%after24hours. The antimicrobial ratios of antimicrobial gauze for E. coli and A. niger could reach99.99%after24hours.An experimental protocol to illuminate the antimicrobial process and mechanism was proposed and applied to AAC under visible light irradiation, using E. Coli, as a test bacteria. The leakage of enzymes from the cells gradually increased to a plateau in2-5h.The leakage of nucleotides showed a smooth and ascending curve within24hours. According to enzyme and nucleotide assays, the inactivation of E. coli, a sequential two-step process that the separation of cell wall from cell membrane and then the destruction of cell membrane were confirmed. In active cell, the intracellular concentration of K+was much higher than the extracellular concentration. With the addition of AAC, a marked increase of the extracellular concentration of K+was brought. The anti-bacterial mechanism was further indicated.