Polydopamine-assisted immobilization of silk fibroin and its derived peptide on chemically oxidized titanium to enhance biological activity in vitro.

Biochemical modification can endow the surface of implants with superior biological activity. Herein, silk fibroin (SF) protein and its anionic derivative peptides (Cs) were covalently immobilized onto a titanium implant surface via a polydopamine layer. The successful conjugation of SF and Cs was revealed by X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and contact angle measurements. The addition of Cs prevented the conformational transition of silk fibroin to silk II. The deposition of apatite on its surface was significantly accelerated, and the bioactive composite coating was observed to enhance protein adsorption and cell proliferation. More importantly, it also promoted the osteogenic differentiation of bone marrow stem cells (BMSCs) for the quantitative and qualitative detection of alkaline phosphatase (ALP) and alizarin red (ARS). Overall, the stable performance and enhanced osteogenic property of the composite coating promote an extensive application for clinical titanium-based implants.

Preparation and biological properties of silk fibroin/nano-hydroxyapatite/hyaluronic acid composite scaffold.

In this study, the silk fibroin/nano-hydroxyapatite/hyaluronic acid (SF/nHAp/HA) composite scaffolds with different HA contents were developed by blending, cross-linking and freeze-drying, and their physicochemical properties and cell biocompatibilityin vitrowere subsequently studied. It was observed that the molecular conformation of the composite scaffolds was mainly composed of silk I and a small amount of theß-sheets structure. On enhancing the HA content, the pore size of the scaffold decreased, while the porosity, water absorption, swelling ratio and mechanical properties were observed to increase. In particular, the SF/nHAp/HA scaffold with a 5.0 wt% ratio exhibited the highest water absorption and mechanical properties among the developed materials. In addition, thein vitrocytocompatibility analysis showed that the bone marrow mesenchymal stem cells exhibited excellent cell proliferation and osteogenic differentiation ability on the SF/nHAp/5.0 wt%HA scaffolds, as compared with the other scaffolds. It can be concluded that the developed composite scaffolds represent a promising class of materials for the bone tissue repair and regeneration.

Preparation and biological properties of silk fibroin/nano-hydroxyapatite/graphene oxide scaffolds with an oriented channel-like structure.

Constructing an ideal bone tissue engineering scaffold has been one of the research hotspots in the biomedical field. Silk fibroin (SF), nano-hydroxyapatite (nHAp) and graphene oxide (GO) are excellent biomaterials, and have been studied and explored extensively. To better mimic natural bone, we fabricated a SF/nHAp/GO hybrid scaffold with an oriented channel-like structure by using directional temperature field freezing technology. A comparative analysis was carried out for the SF, SF/nHAp, unoriented SF/nHAp/GO and oriented SF/nHAp/GO scaffolds. The physical and chemical properties were studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and universal mechanical testing. The data showed that the oriented channel-like SF/nHAp/GO porous scaffold expressed high interconnectivity, suitable pore diameter and porosity and anisotropic mechanical properties. Cytocompatibility tests indicated that the oriented channel-like SF/nHAp/GO porous scaffold was more favorable for stimulating bone marrow mesenchymal stem cells (BMSCs) adhesion and proliferation. Additionally, human umbilical vein endothelial cells (HUVECs) grew unimpeded along the channel, indicating it had advantages for vascularization. For further testing in vitro, osteogenic induction was carried out on BMSCs inoculated on the above scaffolds, and then alkaline phosphatase (ALP) activity was tested and cell mineralization was observed. The results indicated that the oriented channel-like SF/nHAp/GO porous scaffold was more conducive to osteogenic differentiation of BMSCs. Hence, the material may prove to be a promising scaffold for bone tissue engineering.