ABSTRACT
The paper addresses laboratory preparation, characterization and in vitro evaluation of antibacterial activity of graphite/TiO2 nanocomposites. Composites graphite/TiO2 with various ratio of TiO2 nanoparticles (30wt.%, and 50wt.%) to graphite were prepared using a thermal hydrolysis of titanylsulfate in the presence of graphite particles, and subsequently dried at 80°C. X-ray powder diffraction, transmission electron microscopy and Raman microspectroscopy served as phase-analytical methods distinguishing anatase and rutile phases in the prepared composites. Scanning and transmission electron microscopy techniques were used for characterization of morphology of the prepared samples. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity, using four common human pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa). Antibacterial activity of the graphite/TiO2 nanocomposites could be based mainly on photocatalytic reaction with subsequent potential interaction of reactive oxygen species with bacterial cells. During the antibacterial activity experiments, the graphite/TiO2 nanocomposites exhibited antibacterial activity, where differences in the onset of activity and activity against bacterial strains were observed. The highest antibacterial activity evaluated as minimum inhibitory concentration was observed against P. aeruginosa after 180min of irradiation.
Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Graphite/chemistry , Light , Nanoparticles/chemistry , Titanium/chemistry , Bacteria/drug effects , Bacteria/radiation effects , HumansABSTRACT
This paper describes laboratory preparation, characterization and antibacterial activity testing of ZnO/kaoline composites. ZnO/kaoline composites with 50 wt.% of ZnO were laboratory prepared, dried at 105 °C and calcined at 500 °C. XRPD analysis revealed that thermal treatment caused the phase transformation of Zn containing precursor into ZnO. Scanning and transmission electron microscopy techniques were used for characterization of morphology of the prepared samples. A standard microdilution test was used for evaluation of antibacterial activity using four common human pathogens (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa). Daylight was used for induction photocatalytically based antibacterial activity. Second possible explanation of antibacterial activity of ZnO/kaoline could be the presence of biologically available forms of zinc. During the antibacterial activity assays the ZnO/kaoline composites exhibited antibacterial activity, where differences in an onset of the antibacterial activity and activity against bacterial strains were observed. The highest antibacterial activity was observed against S. aureus, where the lowest value of minimum inhibitory concentration was determined equal to 0.41 mg/ml.
