Antibacterial silver-containing silica glass prepared by sol-gel method

Recently, various inorganic antibacterial materials containing silver have been developed and some of them are in commercial use. Colorless and more c hemically durable materials which slowly release the silver ion for a long period are, however, desirable to be developed far medical applications suc h as composite resin for dental restoration. In the present study, Si(OC2H5 )(4), Al(NO3)(3). 9H(2)O, AgNO3, HNO3, C2H5OH and H2O solutions with variou s Al/Ag atomic ratios under a constant Si/Ag atomic ratio of 1/0.023 were k ept at 40 degrees C for gelation and drying. Thus obtained gels were pulver ized into fine powders with average particle size of approximately 10 mu m and then heat-treated at 900-1000 degrees C for 2 h. For the composition Al /Ag = 0, a yellow-colored glass was formed, since the silver existed in the form of metallic colloids in the glass. However, for the compositions Al/A g greater than or equal to 1, colorless glasses were successfully obtained, since the silver existed in the form of Ag+ ions in the glasses. For the c omposition Al/Ag = 0, the silver ions got released rapidly into the water, whereas, for the compositions Al/Ag greater than or equal to 1, they gradua lly got released into the water at a controlled rate. A composite of the ob tained powders with Al/Ag atomic ratio of I with Bis-GMA/TEGDMA in 70:30 we ight ratio showed excellent antibacterial property. The sol-gel derived sil ica glass powders containing silver with compositions Al/Ag greater than or equal to I are believed to be useful as an antibacterial material for medi cal applications such as filler of composite resin for dental restoration. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.