Cytotoxicity of Silver Doped Bioactive Glass Microparticles in Human Leukocytes

Objectives: The aims of the study were to characterize the addition of silver ion to bioactive glasses 58S (BG) and to compare the cytotoxic effects of the BG with silver-doped BG (BGAg) in human leukocytes.
Methods: Glasses samples belonging to the system 58SiO_2^●(36-x)CaO_^●6P₂O_5^●xAg₂O, where x=0 or 1mol%, respectively, were synthesized via sol–gel method, filtered under mesh 200 and characterized by scanning electron microscopy (SEM), atomic-force microscopy (AFM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Surface-enhanced Raman spectroscopy (RAMAN-SERS). Cytotoxicity was assessed in Ficoll-isolated human peripheral blood nonnuclear cells (PBMCs) from healthy volunteers (n=9), using a commercial kit based on resazurin reduction. Fluorescence intensity was measured after 24h incubation with serial dilutions of BG (range from 2–0.015% wt/vl) and BGAg (range from 0.015–0.00008% wt/vl).
Results: The SEM and AFM images showed micrometric particles (≤74 μm) with irregular fibrous and porous surface. The TGA, XRD, FTIR and RAMAN-SERS analyses confirmed silver content within silica microparticles (BGAg), without any structural and physicochemical changes of BG. Cell viability assays demonstrated dose-dependent results for BG and BGAg. Samples incubated with the BGAg presented higher toxicity (LC50=0.005%) compared to BG (LC50=0.106%).
Conclusions: Addition of Ag to BG might increase the biomaterial cytotoxicity of human cells. Analyses of ion release and the immunomodulatory activity of the samples are necessary to improve BGAg biocompatibility in human tissues.