title: Non-cytotoxic antibacterial silver-coumarin complex doped sol-gel coatings.
abstract: Microbial colonisation on clinical and industrial surfaces is currently of global concern and silane based sol-gel coatings are being proposed as potential solutions. Sol-gels are chemically inert, stable and homogeneous and can be designed to act as a reservoir for releasing antimicrobial agents over extended time periods. In the present study, silver nitrate (AgN) and a series of silver coumarin complexes based on coumarin-3-carboxylatosilver (AgC) and it is 6, 7 and 8 hydroxylated analogues (Ag6, Ag7, Ag8) were incorporated into sol-gel coatings. The comparative antibacterial activity of the coatings was determined against meticillin resistant Staphylococcus aureus (MRSA) and multidrug resistance Enterobacter cloacae WT6. The percentage growth inhibitions were found in the range of 9.2 (±2.7)-66.0 (±1.2)% at low silver loadings of 0.3% (w/w) with E. cloacae being the more susceptible. Results showed that among the Ag coumarin complexes, the Ag8 doped coating had the highest antibiofilm property. XPS confirmed the presence of silver in the nanoparticulate state (Ag(0)) at the coating surface where it remained after 4 days of exposure to bacterial culture. Comparative cytotoxicity studies revealed that the Ag-complex coatings were less toxic than the AgN coating. Thus, it can be concluded that a sol-gel matrix with Ag-coumarin complexes may provide non-toxic surfaces with antibacterial properties.
authors.affiliation: Centre for Research in Engineering Surface Technology (CREST), FOCAS Institute, Dublin Institute of Technology, Dublin 8, Ireland.
authors.forename: Swarna
authors.initials: S
authors.lastname: Jaiswal
authors.forename: Kunal
authors.initials: K
authors.lastname: Bhattacharya
authors.forename: Maeve
authors.initials: M
authors.lastname: Sullivan
authors.forename: Maureen
authors.initials: M
authors.lastname: Walsh
authors.forename: Bernadette S
authors.initials: BS
authors.lastname: Creaven
authors.forename: Fathima
authors.initials: F
authors.lastname: Laffir
authors.forename: Brendan
authors.initials: B
authors.lastname: Duffy
authors.forename: Patrick
authors.initials: P
authors.lastname: McHale
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000737:chemistry* / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003374:Coumarins / Q000737:chemistry*; D016972:Enterobacter cloacae / Q000187:drug effects; D005782:Gels / Q000737:chemistry*; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008962:Models, Theoretical; D012834:Silver / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D003374:Coumarins; D005782:Gels; D012834:Silver; C030123:coumarin