In Situ Spectroscopic Screening of Osteosarcoma Living Cells on Stoichiometry-Modulated Silicon Nitride Bioceramic Surfaces

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• 作者：Giuseppe Pezzotti ; Bryan J. McEntire ; Ryan Bock ; Wenliang Zhu ; Francesco Boschetto ; Alfredo Rondinella ; Elia Marin ; Yoshinori Marunaka ; Tetsuya Adachi ; Toshiro Yamamoto ; Narisato Kanamura ; B. Sonny Bal
• 刊名：ACS Biomaterials Science & Engineering
• 出版年：2016
• 出版时间：July 11, 2016
• 年：2016
• 卷：2
• 期：7
• 页码：1121-1134
• 全文大小：913K
• ISSN：2373-9878

文摘

Osteosarcoma cell viability, proliferation, and differentiation into osteoblasts on a silicon nitride bioceramic were examined as a function of chemical modifications of its as-fired surface. Biological and spectroscopic analyses showed that (i) postsintering annealing in N₂ gas significantly improved apatite formation from human osteosarcoma (SaOS-2) cells; (ii) in situ Raman spectroscopic monitoring revealed new metabolic details of the SaOS-2 cells, including fine differences in intracellular RNA and membrane phospholipids; and (iii) the enhanced apatite formation originated from a high density of positively charged surface groups, including both nitrogen vacancies (V_N³⁺) and nitrogen N–N bonds (N₄⁺) formed during annealing in N₂ gas. At homeostatic pH, these positive surface charges promoted binding of proteins onto an otherwise negatively charged surface of deprotonated silanols (SiO^–). A dipole-like electric-charge, which includes V_N³⁺/N₄⁺ and SiO^– defective sites, is proposed as a mechanism to explain the attractive forces between transmembrane proteins and the COO^– and NH²⁺ termini, respectively. This is analogous to the mechanism occurring in mineral hydroxyapatite where protein groups are specifically displaced by the presence of positively charged calcium loci (Ca⁺) and off-stoichiometry phosphorus sites (PO₄^2–).