title: Elucidation of cell killing mechanism by comparative analysis of photoreactions on different types of bacteria.
abstract: The mechanism of biocidal action of nano titania on Escherichia coli and Staphylococcus aureus has been evaluated by various biochemical techniques like lipid peroxidation, hydrolysis of orthonitrophenol β-D-galactopyranoside, estimation of protein-amino acid and bacterial nucleic acids leakage into solution, in addition to morphology studies by electron microscopy (TEM and SEM) and K(+) ion leakage by inductively coupled plasma optical emission spectrometry. The active anatase phase of nano titania has been synthesized by sol-gel and pulverization techniques to obtain particle sizes averaging around 11 nm. The nano semiconductor with a bandgap of 3.2 eV responds well to the UV source to liberate reactive oxygen species (ROS). Gram negative bacteria easily succumb to the ROS at a faster rate than gram-positive bacteria with an observable difference in the mode of attack. The use of analytical techniques revealed the release of peroxidized lipid (26 nmol mL(-1) ) and protein content (370 μg mL(-1)) with a K(+) ion concentration of 22 000 ppb on complete destruction of E. coli.
authors.affiliation: Center for Nanobiosciences, Jain University, Ramanagaram, Bangalore, India.
authors.forename: S
authors.initials: S
authors.lastname: Swetha
authors.forename: Maheshwari Kumari
authors.initials: MK
authors.lastname: Singh
authors.forename: K U
authors.initials: KU
authors.lastname: Minchitha
authors.forename: R Geetha
authors.initials: RG
authors.lastname: Balakrishna
mesh_terms: D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects*; D006868:Hydrolysis / Q000187:drug effects / Q000528:radiation effects; D015227:Lipid Peroxidation; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects*; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D055668:Photochemical Processes; D011188:Potassium / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013054:Spectrophotometry, Atomic; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects*; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium; D011188:Potassium