Antimicrobial properties of bimetallic-containing mesoporous bioglass against Enterococcus faecalis

Various pulp-covering materials offer advantages in regenerative root canal treatment, but each has limitations, highlighting the need for more effective antibacterial strategies for pulp repair and regeneration. Mesoporous bioactive glasses (MBG) show significant biological activity, making them valuable in tissue/dental repair. Silver-incorporated MBG exhibits promising antibacterial effects against various bacteria; copper ions are crucial in regulating angiogenesis signals. Co-loading copper and silver in bioactive glasses has been explored to address clinical challenges. This study modified the preparation of silver-copper bimetallic mesoporous bioactive glass, analyzing their textural properties and antibacterial activity against Enterococcus faecalis.

The silver-copper co-loaded bioactive glass (designated as AgCu/80S) was synthesized using a sol-gel technique with modifications. Textural analyses were carried out via X-ray diffraction, UV-Vis spectroscopy, Brunauer-Emmett-Teller analysis, and transmission electron microscope. The ion-releasing activity determined using inductively coupled plasma-mass spectrometry, and the antibacterial activity against E. faecalis was assessed through disk diffusion and kinetic bacterial growth curve.

The modification led to weaker crystallization of calcium silicate, altering ion-releasing and antibacterial activities. Ag3Cu2/80S exhibited the highest released silver ion concentration at 112.6 ppm, with an inhibition zone of 9.09 ± 0.09 mm in disk diffusion assays. However, the inhibition zone of Ag2Cu3/80S was 9.92 ± 0.04 mm, implying that the antibacterial activity may not only be influenced by silver ions.

The AgCu/80S showed a potential antibacterial activity against E. faecalis, whereas further research on AgCu/80S glasses is necessary to optimize ion release conditions, assess bioactivities, and explore potential dental applications.