Antibiofilme effect and stem cell viability of bioactive SiO2-CaO-P2O5 gel-glass with different silica-content

摘要

Bioactive glass is a class of biomaterials that has the potential for application in medical and dental devices for replacement, regeneration and repair of hard and soft tissue . Due to some biological properties which show a strong relationship with the bioactive glass dissolution rate, ions release and pH environment, an evaluation was made in this study of the antibiofilm effect and stem cell viability of the 60%SiO_2-36%CaO-4%P_2O_5 (A) and 80%SiO_(2-)15%CaO-5%P_2O_5 (B) glass compositions (mol%). The glass was synthesized by the sol-gel method using stoichiometric amounts of tetraethoxysilane (Si(OC_2H_5)_4), triethylphosphate (OP(OC_2H_5)_3), and calcium nitrate tetrahydrate (Ca(NO_3)_2-4H_2O) under acidic conditions. Both samples were bioactive when immersed in simulated body fluid (SBF) but with different hydroxycarbonate apatite layer formation rates (more intense for glass A). Comparing the pH variation for all samples during this test, the most abrupt change occurred for glass A in the first few hours, justifying its higher antibiofilm effect against Streptococcus mutans (ATCC 25175). The lowest pH variation was observed for sample B, indicating that the solubility of this sample is lower than the other because the pH variation has a direct relationship with cation exchange from the glass with protons from the solution, such as calcium release from the sample to the media . For in vitro viability testing, the mesenchymal stem cells obtained from the pulp of deciduous exfoliated teeth were cultivated with the bioactive glass at different concentrations (0-125 mg/mL) and cell viability was assessed by MTT assay. Glass B showed significantly higher cell viability in comparison with glass A at the concentrations of 0.125,125 and 12.50 mg/mL for 2 days. These results indicate that the higher solubility of glass A favors the bioactivity and antibiofilm effect of the system but higher increases in the concentration of ions in the cell culture medium as a result of the degradation appear to inhibit cell proliferation. Therefore, by only varying the composition, it is possible to control the degradability and bioactivity levels of the glass, providing a more stable local microenvironment which is favorable for the cells.