Preparation and in vitro cell-biological performance of sodium alginate/nano-zinc silicate co-modified calcium silicate bioceramics
Abstract
Sodium alginate/nano-zinc silicate (SA/nano-ZS) co-modified calcium silicate bioceramics (Na/Zn-CS) were prepared via the spin-coating process. X-ray diffraction patterns indicated the surface components of Na/Zn-CS disks were composed of calcium silicate (pseudowollastonite, CS), sodium calcium silicate and Na/Ca co-doped zinc silicate. Na/Zn-CS disks could induce hydroxyapatite to rapidly deposit on the surface of the disks after being soaked in simulated body fluid (SBF). The pH value of SBF, in which Na/Zn-CS disks were soaked, remained in a relatively low range, whereas that of SBF, in which pure CS disks were soaked, increased with the prolongation of soaking time. Whether rat bone marrow mesenchymal stem cells (rBMSCs) were co-cultured with CS disks or with Na/Zn-CS disks, the extracellular matrix mineralization of rBMSCs could be observed, which suggests the released silicon from the samples possesses osteoinductivity. F-actin staining images of rBMSCs revealed that the attachment and the spread of rBMSCs would not be influenced by the inorganic ions released from the samples, but by the interface stability of the cell/material. Furthermore, the surface dissolution rate significantly affected the initial proliferation of rBMSCs. After incubation for 14 days, the alkaline phosphatase (ALP) activity of rBMSCs cultured on the surface of the CS disk spin-coated with 0.1 g mL−1 of SA/nano-ZS suspension (Na/0.1Zn-CS) was much higher than that of rBMSCs cultured on the surface of the pure CS disk, which indicates the released zinc ions can promote the differentiation of rBMSCs. In conclusion, the surface co-modification with SA/nano-ZS is an effective way to improve the dissolution behavior and biological performance of CS bioceramics.