Bioactive Calcium Silico-Phosphate Glasses Doped with Mg2+ and/or Zn2+: Biocompatibility, Bioactivity and Antibacterial Activity

Abstract

Bioactive glasses in the SiO₂-CaO-P₂O₅ system represent emerging materials for hard-tissue-regeneration applications. This article focuses on the synthesis, characterization, and biological interaction of glasses doped with Mg²⁺ and/or Zn²⁺, with an emphasis on their effects on biomineralization, antibacterial behavior, and interactions with preosteoblasts from the MC3T3-E1 cell line. The bioglasses were synthesized using the sol-gel method, and the vitreous nature remained predominant even after thermal treatment at 600 °C for 2 h. From an in vitro perspective, the synthesized bioglasses demonstrated strong cell adhesion and proliferation (notably in the case of Mg²⁺ doping), low cytotoxicity, and antibacterial properties (especially in Zn²⁺-doped samples). Additionally, the simultaneous doping with Mg²⁺ and Zn²⁺ of the bioactive glass matrix is a prospective strategy for developing biomaterials with a "dual" biological characteristics-both osteoinductive and antibacterial.

Keywords: antibacterial activity; bioactive glass; biomineralization.

Figure 1

Synthesis scheme of bioglass powders.

Figure 2

Complex thermal analysis of gels aged and dried for 72 h at 70 °C: (a)—DTA curves; (b)—TG curves.

Figure 3

XRD patterns of gels aged and dried for 72 h at 70 °C.

Figure 4

XRD patterns (a) and FTIR spectra (b) of the materials obtained via heat treatment at 600 °C for 2 h of the gels dried for 72 h at 70 °C.

Figure 5

SEM images ((a)–M0; (b)–M1; (c)–M2; (d)–M3) and EDAX spectra (e) of the synthesized vitreous powders.

Figure 6

SEM images ((a)–M0; (b)–M1; (c)–M2; (d)–M3) and EDX spectra (e) for the synthesized glass powders immersed in SBF for 14 days, at 37 °C.

Figure 7

(A). The viability and proliferation profile of MC3T3-E1 preosteoblasts in contact with the bioactive glasses (p < 0.01 **; p < 0.001 ***; p < 0.0001 ****), compared to a standard TCPS control. (B) Cytotoxicity of the materials assessed by means of the LDH assay. Similar levels of cytotoxicity on all tested composites were observed, with statistically insignificant differences, suggesting good biocompatibility. (C) Qualitative evaluation of the viability and proliferation of preosteoblasts in contact with the bioactive glasses by means of the Live/Dead assay. Live cells are labeled with calcein and stained green, while dead cell nuclei are stained red with EtBr. Scale bar for all images, 50 µm. (D) Quantification of green fluorescence (live cells) levels and red fluorescence (dead cell nuclei) levels in all composites.

Figure 8

The antibiofilm effect of bioactive glasses after 24 h of incubation in liquid media for tested strains was compared using two-way ANOVA and Tukey’s multiple comparisons tests. The results were considered statistically significant (* p < 0.026; ** p < 0.003; *** p ≤ 0.0004; **** p < 0.0001).