Mesoporous bioactive scaffolds based on the 14.6Li2O⋅8.6ZrO2⋅67.3SiO2⋅9.5Al2O3 glass-ceramic as drug delivery for bone regeneration

Abstract

Bioactive scaffolds based on the 14.6Li2O⋅8.6ZrO2⋅67.3SiO2⋅9.5Al2O3 glass-ceramic for use in drug delivery is presented. Powders of the parent glass (212 mm > particle size >38 mm) were heat-treated at 725 °C for 3 h for surface crystallization. They were subjected to a chemical attack with 6 vol% of hydrofluoric acid for 40 s for partial dissolution of the residual glass, and washed with deionised water and calcium carbonate. Structural and microstructural analyses were performed to identify the formed crystalline phases and porosity. Mesopores with 2.05 nm-radius were detected. The immersion method was used to insert alendronate sodium into the scaffolds. The drug delivering capability was evaluated by infrared spectroscopy and thermogravimetric analysis (TG). The FTIR spectra showed the typical functional groups existing in the alendronate sodium, confirming their impregnation into the scaffold's pores. Moreover, the TG thermograms showed loss weights of ∼2% indicating the effective inoculation of the drug into the scaffold. The bioactivity of the material was evaluated through calcium phosphate layer formation after incubation in a simulated body fluid for up to 28 days (37 ± 1 °C) and then analysed by infrared spectroscopy (FTIR). Calcium phosphates were identified after 24 h of immersion indicating the bioactivity of the glass-ceramic. The cytotoxicity and hemocompatibility tests showed that the LZSA glass-ceramic scaffold is not considered toxic to the human body at concentrations below 40 μg/mL and does not show hemolytic effects at all tested concentrations. Thus, the obtained microstructure renders the material promising for use as a drug delivery agent for bone regeneration.