Preparation Of Silver-doped Mesoporous Silica Coating And Characterization Of Its Antimicrobial Activity

Studies have shown that dental resin base material easily remain bacteria, increasing inthe morbidities of patient,s dental caries, periodontal disease and denture stomatitis. How toimprove the denture base antibacterial properties has become a hot topic of dental materialsresearch, but there is no method can completely meet the clinical needs. Among variousantibacterial metals, silver is known to have a wide antibacterial spectrum and relatively highsafety.Silver，when loaded onto inorganic carrier and released from it slowly by design, actas inorganic disinfectants, which are superior in terms of safety,durability and heatresistance when compared with conventional organic ones.As for inorganic carriers, somecompounds such as zeolite, apatite, phosphates, titanium oxides and glass have been used sofar. SiO₂, possessing porous structure, can adsorb various ions easily in its pores and on itssurfaces. Because of its adsorption properties, SiO₂is expected to be one of the mostpromising carriers suitable for development of high performance antibacterial andbactericidal materials. The aim of this study was to develop a kinds of denture base resinsurface antibacterial coatings，in which silver loaded mesoporous nano-SiO₂was acted as theantibacterial agent.Mesoporous nano-SiO₂was prepared by sol–gel method.The reactants for the synthesisof mesoporous nano-SiO₂at room temperature were tetraethylsilicate （TEOS）, distilledwater, ethanol, cetrimonium bromide （CTAB）, either NaOH or NH4OH can be used as abase source. Particle size analysis showed that the mesoporous nano-SiO₂particle size wasaffected by many synthetic factors. The structure of the sample（the particle size of220-342nm） has been characterized by SEM, X-ray diffraction and nitrogenadsorption/desorption isotherms. The results demonstrated the existence of an orderedmesoporous structure, for specific surface area1097.8m²/g, pore volume0.82cm³/g and poresize2.4nm. Finally, the sample was estimated.Mesoporous nano-SiO₂can be used as a carrier to prepare inorganic antibacterialmaterials by adsorbing silver. Through calcination and extraction experimental methodscould remove the remained template in the mesoporous, and the experimental conditions of extraction and decompression were in favor of silver impregnation. The synthesis of AgClnanoparticles inside the pores of mesoporous nano-SiO₂was achieved in two steps. AgNO₃was impregnated into the pores of mesoporous nano-SiO₂in the first step and the AgNO₃inthe pores was converted into AgCl by ion exchange of the NO3-with Cl_by exposing theAgNO₃nanoparticles to a dry HCl vapor. We prepared four samples， where theconcentration of the AgNO₃solution used for the impregnation were0.1mol/l、0.2mol/l、0.5mol/l and1mol/l.The antibacterial properties of the AgCl loaded Mesoporous nano-SiO₂samples wereexamined. Candida albicans（ATCC10231）was selected as the indicator of experimentalbacteria. The antibacterial effects were evaluated by the minimal bactericidal concentration（MBC）of the samples. the antibacterial results showed that the sample of1mol/l AgNO₃impregnating concentration had stronger antibacterial abilities than the other samples，so weselect1.0mol/L silver nitrate as the impregnating concentration.We prepared the tetraethyl silicate and3-glycid oxypropyl trimethoxy silane mixedcoating, then dispersed silver loaded mesoporous nano-SiO₂into the coating by the physicaldoping method. the quality scores of the silver loaded mesoporous nano-SiO₂in the coatingwere0.0%，0.5%，1.0%and2.0%respectively. The antibacterial effects were evaluated bythe antibacterial rate，the results demonstrated that the antibacterial rate of the sample2.0%quality score reached99.5%, slightly better than the others，and could met the clinicaldemands.