[show abstract][hide abstract] ABSTRACT: Among a variety of polymers, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a microbial polyester, with biodegradable, nonantigenic, and biocompatible properties, is attracting more and more attention in tissue engineering. Hydroxyapatite (HA), similar to the mineral component of natural bone, is known to be osteoconductive, nontoxic, and noninflammatory. In this study, aligned and random-oriented PHBV nanofibrous scaffolds loaded with HA nanoparticles were fabricated through electrospinning technique. Mesenchymal stem cells (MSCs) derived from rat bone marrow were used to investigate the effects of HA and orientation of fibers on cell proliferation and differentiation in vitro. Cell proliferation tested with CCK-8 assay indicated that the MSCs attached and proliferated more favorably on random-oriented PHBV nanofibrous meshes without HA. After one, two and four weeks of cell seeding, osteogenic markers including alkaline phosphate (ALP), osteocalcin (OCN), and mineralized matrix deposits were detected, respectively. The results indicated that the introduction of HA could induce MSCs to differentiate into osteoblasts. Moreover, 3D PHBV/HA scaffolds made from aligned and random-oriented nanofibers were implanted into critical-sized rabbit radius defects and exhibited significant effects on the repair of critical bone defects, implying their promising applications in bone tissue engineering.
[show abstract][hide abstract] ABSTRACT: Microenvironments in which cells live play an important role in the attachment, growth and interactions of cells. To mimic the natural structure of extracellular matrices, electrospinning was applied to fabricate biomaterials into ultrafine fibers. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biocompatible and biodegradable polyester, has been shown to be an excellent biomaterial candidate for tissue engineering. In this study, five types of PHBV fibrous scaffolds with different diameters and orientations were obtained by changing solvents, concentration of electrospun solution and collector. Three kinds of scaffolds with good continuity and suitable mechanical properties, selected according to the morphology and mechanical properties of the scaffolds, were used for studying the influence of fiber diameter and orientation on growth behavior of bone-marrow-derived mesenchymal stem cells (MSCs). The results indicated that the random-oriented nanofibrous scaffold is most favorable for cell growth compared to other scaffolds, while the microfibrous scaffold resulted in the lowest viability of MSCs. The orientation of nanofibers showed a distinct effect on cell morphology by guiding cell skeleton extension. Both the random-oriented and aligned PHBV nanofibrous scaffolds showed to be good candidates for applications in tissue engineering.
[show abstract][hide abstract] ABSTRACT: Sodium butyrate (NaBu) is regarded as a potential reagent for cancer therapy. In this study, a specific breast cancer cell population that is resistant NaBu treatment was identified. These cells possess cancer stem cell characters, such as the capability of sphere formation in vitro and high tumor incident rate (85%) in mouse model. Forty percent of the NaBu resistant cells express the cancer stem cells marker, the CD133, whereas only 10% intact cells present the CD133 antigen. Furthermore, the endogenous expressing c-MET contributes to the survival of cancer stem cell population from the treatment of NaBu. The CD133+ group also presents a higher level of c-MET. A combination treatment of MET siRNA and NaBu efficiently prohibited the breast cancer progression, and the incident rate of the tumor decrease to 18%. This study may help to develop a new and alternative strategy for breast cancer therapy.
PLoS ONE 01/2012; 7(1):e30143. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biodegradable polyester, has been a good candidate of biomaterial employed in tissue engineering. However, the PHBV film is hydrophobic and has no recognition sites for cell attachment. In this study, PHBV films are activated by ammonia plasma treatment to produce amino groups on the surface, followed by sequential reactions with a heterobifunctional cross-linker containing a segment of poly(ethylene glycol) (PEG) and further with RGD-containing peptides. XPS analyses of modified surfaces after each reaction step reveal that the RGD-containing peptides have been covalently grafted onto PHBV films. The result of cell viability assay indicates that the RGD-modified PHBV films exhibit a distinctly improved cellular compatibility. Moreover, according to the results of serum adsorption tests by optical waveguide lightmode spectroscopy (OWLS) and fibrinogen adsorption tests by enzyme-linked immunosorbent assay (ELISA) on unmodified and modified PHBV surfaces, the introduced PEG chains can significantly decrease the nonspecific adsorption of proteins from serum and fibrinogen from plasma, thus decreasing the risk of thrombus formation and improving the blood compatibility of implanted materials.
[show abstract][hide abstract] ABSTRACT: ABSTRACT: The biggest challenge in the field of gene therapy is how to effectively deliver target genes to special cells. This study aimed to develop a new type of poly(D,L-lactide-co-glycolide) (PLGA)-based nanoparticles for gene delivery, which are capable of overcoming the disadvantages of polyethylenimine (PEI)- or cationic liposome-based gene carrier, such as the cytotoxicity induced by excess positive charge, as well as the aggregation on the cell surface. The PLGA-based nanoparticles presented in this study were synthesized by emulsion evaporation method and characterized by transmission electron microscopy, dynamic light scattering, and energy dispersive spectroscopy. The size of PLGA/PEI nanoparticles in phosphate-buffered saline (PBS) was about 60 nm at the optimal charge ratio. Without observable aggregation, the nanoparticles showed a better monodispersity. The PLGA-based nanoparticles were used as vector carrier for miRNA transfection in HepG2 cells. It exhibited a higher transfection efficiency and lower cytotoxicity in HepG2 cells compared to the PEI/DNA complex. The N/P ratio (ratio of the polymer nitrogen to the DNA phosphate) 6 of the PLGA/PEI/DNA nanocomplex displays the best property among various N/P proportions, yielding similar transfection efficiency when compared to Lipofectamine/DNA lipoplexes. Moreover, nanocomplex shows better serum compatibility than commercial liposome. PLGA nanocomplexes obviously accumulate in tumor cells after transfection, which indicate that the complexes contribute to cellular uptake of pDNA and pronouncedly enhance the treatment effect of miR-26a by inducing cell cycle arrest. Therefore, these results demonstrate that PLGA/PEI nanoparticles are promising non-viral vectors for gene delivery.
Nanoscale Research Letters 01/2011; 6:447. · 2.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aligned and randomly oriented chitosan nanofibers were prepared by electrospinning. The fibers were modified with the RGD cell-adhesive peptide through a heterobifunctional crosslinker containing a segment of poly(ethylene glycol) (PEG). PEG rendered the surface hydrophilic and provided flexible spacers, allowing the preservation of the bioactivity of further captured RGD peptides. NIH 3T3 cells were used to test the cellular compatibility of these chitosan nanofibrous scaffolds. Cell morphology and viability were investigated by SEM, fluorescent staining and cell counting. The results indicate that RGD-modified surfaces significantly improve the cellular compatibility of chitosan nanofibers and suggest a good candidate as a scaffold employed in tissue engineering.
[show abstract][hide abstract] ABSTRACT: Porous silicon (PS) was incubated in an organic solution of metal acetylacetonates of Mn(acac)(3), Fe(acac)(3), Co(acac)(3), and Ni(acac)(2) (acac = MeCOCHCOMe) at room temperature. Crystal-like domains were found to be spontaneously self-assembled on PS surfaces by atomic force microscopy (AFM). Spectroscopic studies with attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that the domains were grown from metal acetylacetonates. Current sensing atomic force microscopy (CSAFM) was used to measure the I-V curves of domains in nanoscale and specific step-jump currents on the manganese and cobalt acetylacetonate domains were surprisingly detected.
The Journal of Physical Chemistry B 01/2007; 110(48):24565-70. · 3.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: We have studied the electrical and light-emitting behaviour as well as the lifetime of electroluminescent (EL) cells which consist of naphthoylimide (NPL) as the emitting layer and poly(3-octythiophene) (P3OT) doped with poly(N-vinylcarbazoe) (PVK) as the hole transport layer sandwiched between indium-tin-oxide (ITO) and aluminium (Al) electrodes. The mixed polymer (P3OT : PVK) layer and the emitting layer were deposited by spin coating and by vacuum deposition. When the ITO substrate was cooled to near liquid N2 temperature during the deposition of the NPL emitting layer, the brightness of the cells increased. Characterized by atomic force microscopy (AFM), the emitting layer became more amorphous as the deposition temperature decreased. Results collected show that low temperature deposition of organic thin solid films would be a powerful technique for not only the enhancement of electroluminescent brightness but also increasing the lifetime of EL devices. 1998 Kluwer Academic Publishers
Journal of Materials Science Materials in Electronics 07/1998; 9(4):279-282. · 1.49 Impact Factor
[show abstract][hide abstract] ABSTRACT: A novel method for the preparation of unilamellar immunoliposomes is introduced. In this method, the aqueous phase is first encapsulated into reverse micelles passing through the oil-water interface, where the monolayer of lecithin embedded with antibody has been formed to self-assemble into immunoliposomes. The main advantages of this method are that the procedure of preparation is simple with high encapsulation yield and it is favorable for large scale production. As shown by negative staining electronic micrograph, the immunoliposomes are unilamellar and 100-500 nm in size. The UV spectra of immunoliposomes solution and lysis assay show that sheep anti-human IgG has been coated on liposomes.
Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 02/1997; 29(6):617-620.
[show abstract][hide abstract] ABSTRACT: Silane coupling reagent ((CH3O)3Si(CH2)3SH) was self-assembled on the industrial glass substrates to form tow-dimensional organic monolayer and the terminal —SH functional group was oxidized into —SO3H groups in situ. By exploiting the chemisorption properties of the —SO3H group, titanium dioxide (TiO2) thin films were prepared by deposition in aqueous HCI solution of TiCl4 at 80°C. X-ray photoelectron spectroscopy (XPS) analysis showed that TiO2 thin films were successfully prepared, and atomic force microscopy (AFM) images confirmed that the films were consisted of packed TiO2 crystallites over 100 nm in size. TiO2 thin films were in excellent adherence. The synthesis of TiO2 films has a prospect in industrial application.