Development of a transparent, non-cytotoxic, silver ion-exchanged glass with antimicrobial activity and low ion elution

• Glass was ion-exchanged via the spreading method using AgNO3 powder.
• Ag ions penetrated into the glass to the depth of 4.8 μm at 260 °C for 10 min.
• Antimicrobial activity of Ag ion-exchanged glass was over 99.9% after 24 weeks.
• Ag ion exchanged glass was also identified to be non-cytotoxic.
• Eluted concentration of Ag ion was satisfied with the WHO standard level.

We investigated the antimicrobial, cytotoxicity, skin irritation, and ion elution behaviors of glass doped with silver ions with respect to its application to electronic equipment such as phones and tablet screens. The microbes tested were Escherichia coli, Staphylococcus aureus, and Penicillium funiculosum. AgNO3 powder was spread on both sides of aluminosilicate glass, and it was heated to 250–280 °C for 10 min. Under optimized heating conditions (260 °C, 10 min), the antimicrobial activity of ion-exchanged glass against bacteria and fungi was over 99.9% after 24 weeks. The glass failed to irritate the skin of experimental animals and was considered non-cytotoxic. The maximum amount of Ag ions that were eluted from the ion-exchanged glass into drinking water was measured at 0.037 ± 0.003 μg L−1, an amount which is several orders of magnitude below the standard limit of 0.1 mg L−1 in drinking water. Ag ion-exchanged glass had characteristics suitable for use as a display screen, such as a light transmittance of 90% and a surface roughness of 0.704 nm. Our findings suggest that glass doped with silver ions is more hygienic than non-doped glass is, and should be applied to display screens and glassware.

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