Effects of silica–gentamicin nanohybrids on osteogenic differentiation of human osteoblast-like SaOS-2 cells

Abstract

Introduction In recent years, there has been an increasing interest in silica (SiO 2 ) nanoparticles (NPs) as drug delivery systems. This interest is mainly attributed to the ease of their surface functionalization for drug loading. In orthopedic applications, gentamicin-loaded SiO 2 NPs (nanohybrids) are frequently utilized for their prolonged antibacterial effects. Therefore, the possible adverse effects of SiO 2 –gentamicin nanohybrids on osteogenesis of bone-related cells should be thoroughly investigated to ensure safe applications. Materials and methods The effects of SiO 2 –gentamicin nanohybrids on the cell viability and osteogenic differentiation of human osteoblast-like SaOS-2 cells were investigated, together with native SiO 2 NPs and free gentamicin. Results The results of Cell Count Kit-8 (CCK-8) assay show that both SiO 2 –gentamicin nanohybrids and native SiO 2 NPs reduce cell viability of SaOS-2 cells in a dose-dependent manner. Regarding osteogenesis, SiO 2 –gentamicin nanohybrids and native SiO 2 NPs at the concentration range of 31.25–125 μg/mL do not influence the osteogenic differentiation capacity of SaOS-2 cells. At a high concentration (250 μg/mL), both materials induce a lower expression of alkaline phosphatase (ALP) but an enhanced mineralization. Free gentamicin at concentrations of 6.26 and 9.65 μg/mL does not significantly influence the cell viability and osteogenic differentiation capacity of SaOS-2 cells. Conclusions The results of this study suggest that both SiO 2 –gentamicin nanohybrids and SiO 2 NPs show cytotoxic effects to SaOS-2 cells. Further investigation on the effects of SiO 2 –gentamicin nanohybrids on the behaviors of stem cells or other regular osteoblasts should be conducted to make a full evaluation of the safety of SiO 2 –gentamicin nanohybrids in orthopedic applications.

Silica–gentamicin nanohybrids: combating antibiotic resistance, bacterial biofilms, and in vivo toxicity

“…The decrease in the zeta potential after the gentamicin loading also contributes to the reduction in the repulsive forces of the nanohybrids, facilitating such network aggregation. This increase in size is consistent with our earlier observations, 27,39 suggesting the loading of gentamicin onto the surface and in the SiO 2 matrix. To some extent, this outcome supports that of Alvarez et al 60 who detected an increase in the size of SiO 2 from 441±5 nm to 511±38 nm after gentamicin loading with a slight decrease in the negative surface charge from −47±5 mV to −43±7 mV, respectively.…”

“…Furthermore, all the embryos exposed to the SiO 2 -G nanohybrids (500 and 1,000 µg/mL) hatched normally (48 hpf) and only showed a slight nonsignificant increase in the cardiac rates. These contradictory findings between our previous in vitro studies 39 and the present in vivo investigations obtained even using the same synthesis strategy of the SiO 2 -G nanohybrids are apparently attributed to the size of the SiO 2 -G nanohybrids (879±264 nm). The chorionic pore diameter hinders the full diffusion of the large-sized nanohybrids into the embryonic tissues.…”

“…Even though the mortality rates of the zebrafish embryos exposed to the SiO 2 -G nanohybrids remained statistically nonsignificant, this addresses the two sides of the same coin: 1) the possible biocompatibility of such delivery systems in orthopedic applications, and 2) the complexities and uncertainties associated with the safety issues of such delivery systems. These uncertainties result from the difficulty to interpret the discrepancies between the results of in vivo and in vitro studies in the present and our previous work, 39 respectively.…”

“…As far as SiO 2 toxicity is concerned, Duan et al 46 have reported a dose-and time-dependent increase in the mortality and hatching rates of zebrafish embryos treated by SiO 2 NPs (62 nm). More specifically, the in vitro toxicity of SiO 2 -G nanohybrids (719±128 nm) has been identified in our earlier study, 39 showing a significant time-dependent decrease in the viability of human osteoblast-like SaOS-2 cells. Only 25%±1% of cells are viable after 5 days at the nanohybrid concentration of 250 µg/mL.…”

“…38 We have recently defined the in vitro effects of SiO 2 -G nanohybrids (719±128 nm) on the osteogenesis of human osteoblast-like SaOS-2 cells, detecting a lower expression of the alkaline phosphatase but enhanced mineralization of the extracellular matrix at 250 µg/mL. 39 To better control the safety of such delivery systems, it is of paramount importance to couple the in vitro toxicological effects of these engineered nanomaterials with in vivo studies in more complex animal models. 40 Zebrafish embryos are an outstanding animal model for screening chemical toxicity and nanotoxicity in vivo due to several advantages: 1) the genome similarity between zebrafish and humans makes the screening relevant to human health; 2) pores (diameter of 0.5-0.7 µm) in zebrafish chorions allow for the permeation of xenobiotics; 3) the transparency of embryos permits microscopic imaging; 4) the survival of embryos in the absence of functional cardiovascular system facilitates accurate cardiotoxicity studies.…”