Highly Efficient Antimicrobial Ceramics Based on Electrically Charged Interfaces.

The increasing threat of multidrug-resistant microorganisms is a cause of worldwide concern. This motivates a necessity to discover new antimicrobial agents or new mechanisms for microorganism eradication, different from those currently used. Here, we report an effective antibacterial ceramic glaze that combines different bactericidal mechanisms. Specifically, the used methodology of the glaze results in glass-free edge crystallizations of feldspar structures at the ceramic surface. A combination of Rutherford backscattering spectroscopy, scanning electron microscopy, and Raman microscopy is used to determine the chemical elements and crystallizations at the ceramic surface. Moreover, Kelvin probe force microscopy demonstrates that the presence of glass-free edges in feldspar needle crystals (semiconductor phase) on a glass matrix (insulator phase) promotes the formation of semiconductor-insulator interface barriers. These barriers act as reservoirs of electric charges of ∼1.5 V, producing a discharge exceeding the microorganism membrane breakdown value (up to 0.5 V). Furthermore, the surface crystallizations account for the formation of a microroughness that limits biofilm formation. Both factors result in high antibacterial activity in the range of R > 4 for Escherichia coli and Staphylococcus aureus. This approach opens new possibilities to attain bactericidal surfaces and to understand the role of physical interaction as a main antimicrobial mechanism.