Xinyu Wang

Different Inhibitory Effect and Mechanism of Hydroxyapatite Nanoparticles on Normal Cells and Cancer Cells In Vitro and In Vivo

Hydroxyapatite (HAP), similar to inorganic phase in bones, shows good biocompatibility and bioactivity as bone defect repairing material. Recently, nanoscaled HAP shows the special properties differing from bulk HAP in physics, chemistry and biology. This paper demonstrates that HAP nanoparticle (nHAP) possesses the ability for inhibiting cancer cell growth in vitro and in vivo. In vitro, after treatment with nHAP for 3 days, proliferation of human cancer cells are inhibited by more than 65% and by less than 30% for human normal cells. In vivo, injection of nHAP in transplanted tumor results in significant reduction (about 50%) of tumor size. The anticancer effect of nHAP is mainly attributed to high amount by endocytosis in cancer cells and inhibition on protein synthesis in cells. The abundant nHAP internalized in cancer cells around endoplasmic reticulum may inhibit the protein synthesis by decreasing the binding of mRNA to ribosome due to its high adsorption capacity for ribosome and arrest cell cycle in G0/G1 phase. nHAP shows no ROS-involved cytotoxicity and low cytotoxicity to normal cells. These results strongly suggest that nHAP can inhibit cancer cell proliferation and have a potential application in cancer treatment.

A Biomimetic Silk Fibroin/Sodium Alginate Composite Scaffold for Soft Tissue Engineering.

A cytocompatible porous scaffold mimicking the properties of extracellular matrices (ECMs) has great potential in promoting cellular attachment and proliferation for tissue regeneration. A biomimetic scaffold was prepared using silk fibroin (SF)/sodium alginate (SA) in which regular and uniform pore morphology can be formed through a facile freeze-dried method. The scanning electron microscopy (SEM) studies showed the presence of interconnected pores, mostly spread over the entire scaffold with pore diameter around 54~532u2009μm and porosity 66~94%. With significantly better water stability and high swelling ratios, the blend scaffolds crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) provided sufficient time for the formation of neo-tissue and ECMs during tissue regeneration. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) results confirmed random coil structure and silk I conformation were maintained in the blend scaffolds. What’s more, FI-TR spectra demonstrated crosslinking reactions occurred actually among EDC, SF and SA macromolecules, which kept integrity of the scaffolds under physiological environment. The suitable pore structure and improved equilibrium swelling capacity of this scaffold could imitate biochemical cues of natural skin ECMs for guiding spatial organization and proliferation of cells in vitro, indicating its potential candidate material for soft tissue engineering.

IKVAV regulates ERK1/2 and Akt signalling pathways in BMMSC population growth and proliferation

The molecular mechanism of bone marrow mesenchymal stem cell (BMMSC) population growth and proliferation, induced by Isoleucyl‐lysyl‐valyl‐alanyl‐valine (IKVAV), was explored in this study.

Preparation and Characterization of Porous Calcium Phosphate Bioceramics

β-tricalcium phosphate (β-TCP) powder and Na 2 O-CaO-MgO-P 2 O 5 glass binder were synthesized and mixed, and then the biodegradable porous calcium phosphate ceramics were successfully prepared by foaming and sintering at 850°C. The as-prepared ceramics possess a high porosity with partial three-dimension interconnected macro- and micro-pores. As in vitro experiment testified, the calcium phosphate ceramics (CPCs) has good degradability.

Change of phase composition and morphology of sonochemically synthesised hydroxyapatite nanoparticles with glycosaminoglycans during thermal treatment

Abstract Based on the preparation of glycosaminoglycans (GAGs) stabilised hydroxyapatite (HAP) nanoparticle suspension via sonochemical synthesis, the change of phase composition and morphology of freeze dried HAP nanoparticles with GAGs was investigated from 500 to 1200°C by TEM, X-ray diffraction, Fourier transform infrared spectroscopy and SEM. Results show that thermal treatment brought the phase transformation and the morphology change of HAP nanoparticles. In the low temperature stage (∼650°C), the samples were mainly composed of HAP as main crystalline phase and β-NaCaPO4 as minor crystalline phase. This phase transformation was mainly attributed to the residues containing sodium derived from combustion of GAGs. The particles were near spherical, and the nanocrystalline nature was retained. In the high temperature stage (650–1200°C), the samples were glass ceramic powders composed of HAP, β-tricalcium phosphate, Na3Ca6(PO4)5, β-NaCaPO4 and Na–Ca–P–O glass phase. The grains rapidly grew into larger particles with morphology transformation from rodlike shape to irregular shape and the size increase from (0·1–0·15) × (0·3–0·5) μm to 1·5–10 μm.

Flexible silk fibroin films modified by genipin and glycerol

Silk fibroin (SF) films, modified by genipin (GP) and glycerol (Gl), with favourable mechanical properties, were obtained by a casting/solvent evaporation method. Simultaneously, the chemical, mechanical and structural properties of the films were examined and analyzed. Compared to uncrosslinked SF films, fibroin solubility of the modified SF (MSF) and Gl/MSF films in the warm water decreased dramatically from 46% to 15%, exhibiting good stability under a physiological environment. The best, valuable modified films with tensile strength of 18.0 MPa, breaking elongation of 171.1% and Youngs modulus of 463.1 MPa were obtained when the GP and Gl content were both 20 wt% and relative to the amount of fibroin. The deformability of the MSF films augmented significantly by increasing the Gl concentration. Fourier transform infrared (FT-IR) results revealed that GP could react with SF macromolecules to form inter- and intra-molecular conjugated covalent bonds. Moreover, the FT-IR and X-ray diffraction (XRD) studies illustrated the GP induced conformational transition from random coil to β-sheet SF chains, yielding MSF and Gl/MSF films with enhanced stable thermal stability. The cytocompatibility of the MSF films were evaluated through MTT assay using L929 fibroblast. Compared to the SF films treated with 75% ethanol, the MSF films exhibited significant cytocompatibility, which was demonstrated by cell adhesion, proliferation and cell morphology. The intrinsic properties and biological results suggest that the MSF films may be potential candidate materials for wound dressing applications or tissue engineering strategies.

Processing and properties of Cfibre/SiCfillers/SiOC composites using solvent free liquid polysiloxane as matrix source

Abstract Carbon fibre reinforced SiOC composites (denoted as Cfibre/SiCfillers/SiOC) were prepared by slurry coating and polymer infiltration pyrolysis (PIP) process. Low viscosity liquid polysiloxane (PSO) and SiC powder were combined at a 1∶1 weight ratio to produce a blend (S-PSO), which was employed as matrix source. Heat treated carbon fibre fabric was adopted as the reinforcement. The lamination process was determined on the basis of cure and rheology investigations on S-PSO. The effects of PIP cycles and temperature of heat treatment of the carbon fibre on the mechanical properties of Cfibre/SiCfillers/SiOC were examined. The results indicate that composites using carbon fibres annealed at 1700°C as reinforcement reached a maximum flexural strength of 300 MPa after six PIP cycles. The resistance of the Cfibre/SiCfillers/SiOC composite to oxidation was also evaluated. Without any protective coatings, the composite retained 60% of its strength after oxidation at 800°C for 3 h in a static air environment.

Evaluation on biocompatibility of biomedical polyurethanes with different hard segment contents

In this paper, polyurethane (PU) materials with different contents of hard segment (20%, 25%, 30%) were prepared based on hexamethylene diisocyanate and polycarbonate diols by solution polymerization. The obtained polycarbonate-urethane (PCU) elastomers were characterized by very good hydrophobic property and excellent resistance to hydrolysis. Hemolysis, recalification time and platelet-rich plasma adhesion were used to evaluate the blood compatibility of the materials. L929 cells cultured with leach liquor of these PU membranes were selected to perform the cytotoxicity experiments. The results indicate that the hemolysis rates of PU membranes are all less than 5%, which can meet the requirement of the national standards for biomaterials. However, compared with 20% and 30% groups, the recalification time of the sample containing 25% hard segment is longer, while the number of platelet adhesion is less. Additionally, cells cultured in the leach liquor of PU membranes with 25% hard segment proliferated relatively more thriving, meaning that this proportion of the material has the lowest cytotoxicity.

Inhibitory Effect of Hydroxyapatite Nanoparticles on K562 Cells

HAP Nanoparticles Was Synthesized by Homogeneous Precipitation. the Size Distribution, Crystallization Degree and Morphology of the Precipitation Were Characterized by Laser Granularity Instrument, X-Ray Diffraction (XRD), and Transmission Electron Microscope (TEM) Respectively. the Prepared HAP Nanoparticles Were Used for the Treatment of Human Chronic Myeloid Leukemia K562 Cells. the Inhibition Effect of the Nanoparticles on the Proliferation of K562 Cells Was Measured by MTT Assay and Growth Curve Test. the Results Showed that the HAP Nanoparticles Inhibit the Proliferation of K562 Cells Dramatically in Vitro. the Likely Inhibition Mechanism of HAP Nanoparticles on the K562 Cells Is that the Nanoparticles Entered into the Dells, Induced a Series of Cell Changes, through Cell Death of Apoptosis, Oncosis and Autoschizis, Thus Led to the Death of K562 Cells.

Influence of hydroxyl-terminated polydimethylsiloxane on high-strength biocompatible polycarbonate urethane films

The present study describes a series of novel polycarbonate urethane films that were fabricated via the solution-casting method from 4,4-methylenebis(cyclohexyl isocyanate) (H12MDI) and 1,4-butanediol (BDO) chain extender as hard segments, poly(1,6-hexanediol)carbonate diols (PCDL) and hydroxyl-terminated polydimethylsiloxane (PDMS) as soft segments, with dibutyltin dilaurate as the catalyst. Varied molar ratios of PDMS (less than 30%) were utilized to enhance the mechanical properties and biocompatibilities. The microstructure and degrees of phase separation were characterized using atomic force microscopy. The chemical structure and surface morphology of the materials were further confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, 1H NMR and 13C NMR, water droplet contact angle and scanning electron microscopy. Thermal properties were measured by differential scanning calorimetry. MTT assay and hemolytic tests were studied for evaluating cellular viability and hemocompatibility of fabricated films using L929 fibroblast cells and adult rabbit blood. The results demonstrated polyurethane films with soft segments partially replaced by PDMS could remarkably improve the biocompatibility while maintaining relatively stable mechanical behavior, making them exciting potential candidates for artificial vessels or other tissue engineering applications.