To generate bioactive coatings for medical implants, a novel procedure has been developed using a coating of mesoporous silica for controlled drug delivery. Plain glass slides were used as substrates. The mesoporous coatings were then loaded with the antibacterial drug ciprofloxacin. The drug release kinetics were investigated in a physiological buffered solution. The drug loading capacity of the unmodified mesoporous coatings was low but could be increased nearly ten-fold (to about 2 mg cm À2 of the macroscopic surface) by functionalizing the mesoporous surface with sulfonic acid groups. To achieve a controlled drug release over an extended time period, further coatings were added. Covering the surface of the drug loaded mesoporous silica layer by dip-coating with bis(trimethoxysilyl)hexane resulted in an organosiloxane layer which retarded the release for up to 30 days. By an additional evaporation coating with dioctyltetramethyldisilazane, the release of ciprofloxacin was prolonged for up to 60 days. The biocompatibility of the different coatings was tested in cell culture assays. The presence of the additional silane-derived hydrophobic coatings somewhat reduced the biocompatibility. The antibacterial efficacy of the materials was demonstrated by using clinically relevant biofilm-forming pathogenic bacteria. A test where the sequential release of ciprofloxacin (in 2 days intervals) and the bacterial viability were tested in parallel showed good concordance in the results. The material where a sulfonate-functionalized mesoporous silica layer is loaded with ciprofloxacin and then coated by an organosiloxane layer derived from bis(trimethoxysilyl)hexane showed the best results with regard to antibacterial efficacy and will further be tested in animal experiments.
Nanoporous silica layers are able to host molecules and release them over a certain period of time. These local drug delivery systems for antibiotics could be a new approach in the treatment of chronic otitis media. The aim of this study was to examine the efficacy of nanoporous silica coatings on middle ear prostheses as a delivery system for antibiotics in vivo. Pseudomonas aeruginosa was inoculated into the middle ear of rabbits to induce an otitis media. The control group received coated Bioverit®II implants without antibiotics. Coated prostheses with loaded ciprofloxacin were implanted into the middle ears of the study group. After 1 week, the rabbits were sacrificed. The clinical examination as well as the microbiological and histological examinations of organs and middle ear irrigation revealed clear differences between the two groups. P. aeruginosa was detected in every middle ear of the control group and was almost completely eliminated in the study group. Organ examinations revealed the presence of P. aeruginosa in the control group and a prevention of a bacterial spread in the study group. The nanoporous silica layer as antibiotic delivery system showed convincing efficacy in induced pseudomonal otitis media in the rabbit.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.