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

Wei He,1 Dina A Mosselhy,2,3 Yudong Zheng,1 Qingling Feng,4 Xiaoning Li,4 Xing Yang,4 Lina Yue,1 Simo-Pekka Hannula2 1School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China; 2Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, Espoo, Finland; 3Microbiological Unit, Fish Diseases Department, Animal Health Research Institute, Giza, Egypt; 4State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, People’s Republic of China Introduction: In recent years, there has been an increasing interest in silica (SiO2) 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 SiO2 NPs (nanohybrids) are frequently utilized for their prolonged antibacterial effects. Therefore, the possible adverse effects of SiO2–gentamicin nanohybrids on osteogenesis of bone-related cells should be thoroughly investigated to ensure safe applications. Materials and methods: The effects of SiO2–gentamicin nanohybrids on the cell viability and osteogenic differentiation of human osteoblast-like SaOS-2 cells were investigated, together with native SiO2 NPs and free gentamicin.Results: The results of Cell Count Kit-8 (CCK-8) assay show that both SiO2–gentamicin nanohybrids and native SiO2 NPs reduce cell viability of SaOS-2 cells in a dose-dependent manner. Regarding osteogenesis, SiO2–gentamicin nanohybrids and native SiO2 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 SiO2–gentamicin nanohybrids and SiO2 NPs show cytotoxic effects to SaOS-2 cells. Further investigation on the effects of SiO2–gentamicin nanohybrids on the behaviors of stem cells or other regular osteoblasts should be conducted to make a full evaluation of the safety of SiO2–gentamicin nanohybrids in orthopedic applications. Keywords: SiO2 NPs, gentamicin, cytotoxicity, ALP activity, mineralizatio

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

Dina A Mosselhy,1–3 Wei He,4 Ulla Hynönen,5 Yaping Meng,6 Pezhman Mohammadi,1 Airi Palva,5 Qingling Feng,7 Simo-Pekka Hannula,2 Katrina Nordström,1 Markus B Linder11Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Espoo, Finland; 2Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, Espoo, Finland; 3Fish Diseases Department, Microbiological Unit, Animal Health Research Institute, Dokki, Giza 12618, Egypt; 4School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China; 5Department of Veterinary Biosciences, Division of Veterinary Microbiology and Epidemiology, University of Helsinki, Helsinki, Finland; 6State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, People’s Republic of China; 7State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, People’s Republic of China Introduction: Antibiotic resistance is a growing concern in health care. Methicillin-resistant Staphylococcus aureus (MRSA), forming biofilms, is a common cause of resistant orthopedic implant infections. Gentamicin is a crucial antibiotic preventing orthopedic infections. Silica–gentamicin (SiO2-G) delivery systems have attracted significant interest in preventing the formation of biofilms. However, compelling scientific evidence addressing their efficacy against planktonic MRSA and MRSA biofilms is still lacking, and their safety has not extensively been studied.Materials and methods: In this work, we have investigated the effects of SiO2-G nanohybrids against planktonic MRSA as well as MRSA and Escherichia coli biofilms and then evaluated their toxicity in zebrafish embryos, which are an excellent model for assessing the toxicity of nanotherapeutics.Results: SiO2-G nanohybrids inhibited the growth and killed planktonic MRSA at a minimum concentration of 500 µg/mL. SiO2-G nanohybrids entirely eradicated E. coli cells in biofilms at a minimum concentration of 250 µg/mL and utterly deformed their ultrastructure through the deterioration of bacterial shapes and wrinkling of their cell walls. Zebrafish embryos exposed to SiO2-G nanohybrids (500 and 1,000 µg/mL) showed a nonsignificant increase in mortality rates, 13.4±9.4 and 15%±7.1%, respectively, mainly detected 24 hours post fertilization (hpf). Frequencies of malformations were significantly different from the control group only 24 hpf at the higher exposure concentration.Conclusion: Collectively, this work provides the first comprehensive in vivo assessment of SiO2-G nanohybrids as a biocompatible drug delivery system and describes the efficacy of SiO2-G nanohybrids in combating planktonic MRSA cells and eradicating E. coli biofilms.Keywords: SiO2, gentamicin, MRSA, antibacterial and antibiofilm effects, nanotoxicity, zebrafis