Antioxidant cerium ions-containing mesoporous bioactive glass ultrasmall nanoparticles: Structural, physico-chemical, catalase-mimic and biological properties

Abstract

The multifunctional biological properties of Ce ions including antioxidant, anti-inflammatory, antibacterial and anti-cancer effects are very encouraging for development of Ce-containing biomaterials with therapeutic properties. Herein, novel Ce³⁺/Ce⁴⁺ ions containing mesoporous bioactive glass ultrasmall nanoparticles (Ce-BGn) were prepared by a facile one-pot ultrasound-assisted sol-gel method. Interestingly, Ce₂O₃ incorporation exerted a significant influence on the particle size and textural properties of mesoporous BGn (SiO₂ - CaO binary glass system). Ce-BGn exhibited ultrasmall nanoparticle size (< 30 nm), mesoporous texture (pore size up to 2.82 nm and pore volume up to 0.191 cm³/g) and large specific surface area ca. 132.9 m²/g. Notably, in situ formation of CeO₂ nanospheres (3-6 nm) was detected at the surface and in the amorphous glass matrix of mesoporous Ce-BGn. Importantly, X-ray photoelectron spectroscopy (XPS) revealed the presence of 72.57 % Ce³⁺ and 27.43 % Ce⁴⁺ at the surface of mesoporous Ce-BGn with Ce³⁺/Ce⁴⁺ ratio = 2.66. Furthermore, mesoporous Ce-BGn exhibited high catalase-mimic activity and showed sustained release of Ce (2.5-32 ppm), Ca (85-327 ppm) and Si (54-200 ppm) ions within 4 weeks along with excellent bone-like hydroxyapatite formation. Finally, the in vitro biological behavior of mesoporous Ce-BGn in cell cultures of human skin fibroblasts (HSF) revealed that mesoporous Ce-BGn (with concentrations up to 300 μg/mL) possess good cyto-biocompatibility. Taken together, novel ultrasmall mesoporous Ce-BGn showed remarkable catalase-mimic activity via surface containing Ce³⁺/Ce⁴⁺ ions which can scavenge ROS (Ce³⁺↔ Ce⁴⁺) and decompose H₂O₂ molecules into H₂O and O₂. In addition to that, Ce-BGn demonstrated sustained release of bioactive ions (Ce, Ca and Si), excellent bone-like hydroxyapatite formation and good cyto-biocompatibility.

Keywords: Antioxidant; Catalase-mimic; Ce(3+)/Ce(4+) ions; Mesoporous bioactive glass; Ultrasmall nanoparticles; Ultrasonic-assisted sol-gel synthesis.