Biocompatibility and antimicrobial efficacy of silver-doped borosilicate bioactive glass for tissue engineering application

Borate bioactive glasses are an auspicious material for tissue engineering applications due to their enhanced dissolution rate, bioactivity, and capacity to integrate therapeutic ions. In this study, borate-based S49B4 bioactive glass doped with silver at mass fraction of 0.5, 1, and 3 wt% were studied for bioactivity, degradation, antibacterial, and cytocompatibility. Thermogravimetric analysis revealed that the bioactive glasses were thermally stable between 600 and 700 °C. Fourier transform infrared spectroscopy and X-ray diffraction confirmed the successful synthesis of an amorphous phase of the doped borosilicate bioactive glasses and the incorporation of silver ion crystals within the structure, as well as associated contributions from borate and silicate network formers in the borosilicate bioactive glass. Morphological evaluation revealed that the borosilicate bioactive glasses exhibit a uniform and spherical shape across all formulations, with the mean particle size varying from 65 to 76 nm. An in-vitro acellular bioactivity in simulated body fluid medium showed that increasing the silver content increased the degradation rate and pH. Besides, scanning electron microscopy and Energy dispersive X-ray spectroscopy analysis revealed an upsurge in apatite production on the BBGs' surfaces as well as incremental Calcium-Phosphate ratio values of 1.50, 1.65 and 1.70 as the silver content increases. The antibacterial effect was tested against Escherichia coli and Staphylococcus aureus, while cytocompatibility was tested against human gingival epithelial cells. Silver integration at 1 wt percent yielded the most promising outcomes, which were particularly bactericidal at 79.8 % for Escherichia coli and 93.41 % for Staphylococcus aureus. Similarly, its Lactate Dehydrogenase percentage is significantly similar to the negative control employed in the study, indicating its biocompatibility. In contrast, 3 wt% silver exhibited the maximum bactericidal activity while also exhibiting mild cytotoxicity. In summary, our research indicates that elevated silver concentration enhances the bioactivity and antimicrobial characteristics of borosilicate bioactive glasses; nevertheless, a higher silver weight percent in this study also increases the possibility of cytotoxicity. It is therefore essential to carefully regulate the amount of silver doping at lower concentrations in order to maximize antibacterial action and minimize toxicity to human cells. The results presented here contribute to our understanding of the prospective use of silver doped borosilicate bioactive glasses as a possible material for tissue engineering applications.