ABSTRACT
The paper reports laboratory preparation, characterization and in vitro evaluation of antibacterial activity of ZnO/graphite nanocomposites. Zinc chloride and sodium carbonate served as precursors for synthesis of zinc oxide, while micromilled and natural graphite were used as the matrix for ZnO nanoparticles anchoring. During the reaction of ZnCl2 with saturated aqueous solution of Na2CO3a new compound is created. During the calcination at the temperature of 500 °C this new precursors decomposes and ZnO nanoparticles are formed. Composites ZnO/graphite with 50 wt.% of ZnO particles were prepared. X-ray powder diffraction and Raman microspectroscopy served as phase-analytical methods. Scanning electron microscopy technique was used for morphology characterization of the prepared samples and EDS mapping for visualization of elemental distribution. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity and antibacterial activity at dark conditions. Common human pathogens served as microorganism for antibacterial assay. Antibacterial activity of ZnO/graphite composites could be based on photocatalytic reaction; however there is a role of Zn(2+) ions on the resulting antibacterial activity which proved the experiments in dark condition. There is synergistic effect between Zn(2+) caused and reactive oxygen species caused antibacterial activity.
Subject(s)
Anti-Bacterial Agents/pharmacology , Graphite/pharmacology , Nanocomposites/chemistry , Zinc Oxide/pharmacology , Anti-Bacterial Agents/chemistry , Graphite/chemistry , Microbial Sensitivity Tests , Microscopy, Electron, Scanning , Photochemical Processes , Spectrum Analysis, Raman , Staphylococcus aureus/drug effects , X-Ray Diffraction , Zinc Oxide/chemistryABSTRACT
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.
Subject(s)
Anti-Bacterial Agents/chemistry , Kaolin/chemistry , Nanocomposites/chemistry , Zinc Oxide/chemistry , Anti-Bacterial Agents/pharmacology , Catalysis , Enterococcus faecalis/drug effects , Escherichia coli/drug effects , Light , Nanocomposites/ultrastructure , Pseudomonas aeruginosa/drug effects , Staphylococcus aureus/drug effects , X-Ray DiffractionABSTRACT
The paper addresses laboratory preparation and antibacterial activity testing of kaolinite/nanoTiO2 composite in respect of the daylight irradiation time. Kaolinite/nanoTiO2 composites with 20 and 40 wt% of TiO2 were laboratory prepared, dried at 105 °C and calcined at 600 °C. The calcination caused transformation of kaolinite to metakaolinite and origination of the metakaolinite/nanoTiO2 composite. X-ray powder diffraction, Raman and FTIR spectroscopic methods revealed titanium dioxide only in the form of anatase in all evaluated samples (non-calcined and calcined) and also transformation of kaolinite to metakaolinite after the calcination treatment. Scanning electron microscopy was used as a method for characterization of morphology and elemental composition of the studied samples. A standard microdilution test was used to determine the antibacterial activity using four human pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa). A lamp with a wide spectrum bulb simulating daylight was used for induction of photocatalysis. The antibacterial assays found all the KATI samples to have antibacterial potency with different onset of the activity when calcined samples exhibited antibacterial activity earlier than the non-calcined. Significant difference in antibacterial activity of KATI samples for different bacterial strains was not observed.
Subject(s)
Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/radiation effects , Kaolin/chemistry , Light , Nanocomposites/chemistry , Titanium/chemistry , Anti-Bacterial Agents/chemistry , Bacteria/drug effects , Catalysis/radiation effects , Kaolin/radiation effects , Nanocomposites/radiation effects , Nanoparticles/chemistry , Nanoparticles/radiation effects , Surface Properties , Time Factors , Titanium/radiation effectsABSTRACT
The novel antibacterial organovermiculites with different mass ratios of chlorhexidine diacetate (CA) were successfully prepared by ion exchange reactions. The resultant organovermiculites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal properties of prepared organovermiculites were investigated by simultaneous thermogravimetry (TG) and differential thermal analysis (DTA). The antibacterial activity of prepared organovermiculites against Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding minimum inhibitory concentration (MIC). Antibacterial studies showed that the organovermiculites strongly inhibited the growth of variety of microorganisms.
