Publications (6) View all
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Article: Effects of pH and initial Ca2+−H2PO4− concentration on fibroin mineralization
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ABSTRACT: In the present study, the effects of pH and initial Ca2+−H2PO4 − (Ca-P) concentration on fibroin mineralization were studied. The crystal growth of calcium phosphates was regulated by regenerated silk fibroin for 8 h (at pH 4.0, 7.0 and 10.0, respectively). Meanwhile, different concentrations of Ca2+ were employed at a certain pH value, keeping the initial Ca-P molar ratio constant at 1.67, i.e., the stoichiometry of hydroxyapatite [Ca10(PO4)6(OH)2, HAP]. The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results demonstrated that, compared to pH 4.0 and 10.0, pH 7.0 promoted the transformation of brushite (CaHPO4·2H2O, DCPD) to HAP. In the composites of mineralized fibroin, DCPD is the main inorganic phase at both relatively low and high pH, while HAP is the main inorganic phase at pH 7.0. Additionally, the initial Ca-P concentration does not affect the kind of inorganic phase in the synthesized mineralized fibroin, but induce to different contents of inorganic mineral and different morphology of DCPD at pH 4.0 and pH 10.0.Frontiers of Materials Science in China 04/2012; 1(3):258-262. -
Article: A novel method to prepare mineralized fibroin fiber
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ABSTRACT: In this paper, a novel method was developed to prepare mineralized fibroin fiber. We used fibroin gel to control the biomineralization of calcium phosphate and obtained one kind of mineralized fibroin fiber with the length of 1–2 mm. It has the potential to be used to enhance the strength of tissue engineering scaffold. Scanning electron microscopy (SEM) results showed that hydroxyapatite (HA) was mainly deposited on the surface of mineralized fiber. Fourier transform infrared spectroscopy (FTIR) results displayed the red shifts of absorption bands of amide II and amide III (9 and 5 cm−1, respectively), which were related to the strong chemical interaction between HA and fibroin. It was also found that HA was at low content (12.5%) and the ability of gelled fibroin to induce mineralization decreased greatly because of the formation of β-structures in gelled fibroin molecules, which showed the importance of molecular structure in the regulation of the biomineralization process.Frontiers of Materials Science in China 04/2012; 1(3):243-246. -
Article: Calcium carbonate microparticles used as a gene vector for delivering p53 gene into cancer cells.
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ABSTRACT: Calcium carbonate (CaCO(3) ) microparticles were for the first time used for efficient delivery of p53 gene to transfect human cancer cells HeLa. CaCO(3) microparticles (2-4 μm) absorbed pEGFP-C1-p53 (expressing GFP-P53 fusion protein) to transfect HeLa cells. Flow cytometer (FCM) was used to evaluate the gene transfection efficiency in HeLa cells, which were stably transduced with a green fluorescent protein gene. In this study, CaCO(3) delivering pEGFP-C1-p53 could transfect about 5% of the tumor cells in culture. However, the efficiency of tumor cell apoptosis was surprisingly up to 80%. Meanwhile, the results of MTT assay and crystal violet staining showed that the CaCO(3) microparticles had low cytotoxicity. These findings showed that CaCO(3) microparticles were perspective to be used as new vectors for gene therapy.Journal of Biomedical Materials Research Part A 04/2012; 100(9):2312-8. · 2.63 Impact Factor -
Article: Preparation of 3-D porous fibroin scaffolds by freeze drying with treatment of methanol solutions
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ABSTRACT: In this study, silk scaffolds with appropriate porous structures were prepared by adjusting solution concentrations and providing treatment with methanol solutions in the way of freeze drying. The effects of the preparation conditions on the microstructures and properties of the scaffolds were discussed. Fibroin solutions with different concentrations of 4, 6, 8, 10 wt% were used respectively to prepare the scaffolds. The effects of the addition of 20 vol% methanol before or after freeze drying to the 4 wt% fibroin solution were investigated. As demonstrated by Scanning Electron Microscope (SEM), the fibroin scaffolds prepared without methanol had porous microstructures composed of thin sheets, and the sizes of the pores decreased with the increase of the fibroin solution concentrations, while the scaffolds prepared in the presence of methanol showed porous microstructures formed by fine-particle aggregates. The porosities and mechanical properties of the prepared fibroin scaffolds under different conditions were tested. The crystalline structures and conformations of the fibroin scaffolds were detected by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD).Chinese Science Bulletin 06/2007; 52(13):1791-1795. · 1.32 Impact Factor -
Article: Effect of solute concentration on fibroin regulated biomineralization of calcium phosphate
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ABSTRACT: In this paper we used UV/Visible method to study the effect of solute concentration on fibroin regulated biomineralization of calcium phosphate. During the reaction process, ultraviolet–visible spectrophotometer was used to track the extinction in the reaction solution. It is found that kinetics of the biomineralization can be strongly affected by the presence of fibroin. Fibroin with higher concentration has more positive effect on the biomineralization process. Under the appropriate reaction conditions, wave crest and wave trough appear in the kinetic curves of fibroin biomineralization. The wave crest and wave trough phenomenon is mainly related with the process of phase separation. X-ray Diffraction (XRD) result shows the calcium phosphate before the wave trough is mainly amorphous calcium phosphate, while after the wave trough crystal of hydroxyapatite (HA) and brushite (DCPD) are the mainly ingredients.Materials Science and Engineering: C. 26(4):639-643.
