Cytocompatibility of Potential Bioactive Cerium-Doped Glasses based on 45S5.

Gianluca Malavasi,Luca Rigamonti,Roberta Salvatori,Gigliola Lusvardi,Alfonso Zambon,Alexandre Anesi,Luigi Chiarini

doi:10.3390/ma12040594

Abstract

The cytocompatibility of potential bioactive cerium-containing (Ce3+/Ce4+) glasses is here investigated by preparing three different glasses with increasing amount of doping CeO2 (1.2, 3.6 and 5.3 mol% of CeO2, called BG_1.2, BG_3.6 and BG_5.3, respectively) based on 45S5 Bioglass® (called BG). These materials were characterized by Environmental Scanning Electron Microscopy (ESEM) and infrared spectroscopy (FTIR) after performing bioactivity tests in Dulbecco’s Modified Eagle Medium (DMEM) solution, and the ions released in solution were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Optical Emission Spectrometry (ICP-OES). The data obtained clearly show that the glass surfaces of BG, BG_1.2 and BG_3.6 were covered by hydroxyapatite (HA), while BG_5.3 favored the formation of a cerium phosphate crystal phase. The cytotoxicity tests were performed using both murine long bone osteocyte-like (MLO-Y4) and mouse embryonic fibroblast (NIH/3T3) cell lines. The cerium-containing bioactive glasses show an increment in cell viability with respect to BG, and at long times, no cell aggregation and deformation were observed. The proliferation of NIH/3T3 cells increased with the cerium content in the glasses; in particular, BG_3.6 and BG_5.3 showed a higher proliferation of cells than the negative control. These results highlight and enforce the proposal of cerium-doped bioactive glasses as a new class of biomaterials for hard-tissue applications.

Highlights

In the last years, rare earth elements have received much attention in the biomaterials field due to their specific properties [1]
The samples were maintained at 1350 ◦ C for 2 h to ensure the optimal melting and mixing of all the oxides, and they were quenched at room temperature on a graphite mold in order to form a cylindrical bar of 1.1 cm in diameter
P2 O5 of the bioactive glass, which should ensure the desired bioactivity, while having CeO2 incorporated in the BG matrix

Summary

Introduction

Rare earth elements have received much attention in the biomaterials field due to their specific properties [1]. Cerium oxide nanoparticles (CeONPs or nanoceria) have received much attention because of their excellent catalytic activities, which are derived from quick interconversion between the oxidation states Ce4+ and Ce3+ [3] This ability is due to a specific feature of the surface of CeONPs: it exhibits oxygen vacancies in the lattice structure arising from the loss of oxygen atoms, alternating between CeO2 and CeO2−x during redox reactions [4,5]. Materials 2019, 12, 594; doi:10.3390/ma12040594 www.mdpi.com/journal/materials (OXI) [6,7] This produces various positive biological effects, such as antioxidant towards almost all noxious intracellular reactive oxygen species (ROS), which stoke the inflammation [8] after surgical operations, as well as for those involving implantation of biomaterials, the so-called surgical stress response [9,10]. Nanoceria has emerged as a material in biological fields such as bioanalysis, biomedicine, drug delivery, and bioscaffolding [11]

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