title: Enhancement of the antibacterial properties of silver nanoparticles using beta-cyclodextrin as a capping agent.
abstract: Silver nanoparticles (AgNPs) were synthesised by reducing silver salts using NaBH(4) followed by capping with varying concentrations of beta-cyclodextrin (beta-CD) and were physically characterised. Antibacterial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was determined by a microtitre well method. The AgNPs were spherical under transmission electron microscopy, whilst dynamic light scattering showed average diameters of capped particles to be smaller (4-7 nm) than their uncapped equivalents (17 nm). Capped particles demonstrated superior photostability when exposed to intense ultraviolet radiation for 4h as well as significantly (P<0.05) higher (up to 3.5-fold) antibacterial activity. The influence of beta-CD concentration was seen to delay bacterial growth, indicating that a Trojan horse mechanism may be occurring owing to bacterial carbohydrate affinity, thereby enhancing silver ion absorption.
authors.affiliation: School of Biological Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland.
authors.forename: Swarna
authors.initials: S
authors.lastname: Jaiswal
authors.forename: Brendan
authors.initials: B
authors.lastname: Duffy
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Jaiswal
authors.forename: Niall
authors.initials: N
authors.lastname: Stobie
authors.forename: Patrick
authors.initials: P
authors.lastname: McHale
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004355:Drug Stability; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D053758:Nanoparticles; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D012834:Silver / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D014466:Ultraviolet Rays; D047392:beta-Cyclodextrins / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D047392:beta-Cyclodextrins; D012834:Silver; C031215:betadex