Papers by Author: Yi Zuo

Abstract: Elimination of the residual microorganisms from an infectious bone defects and the prevention of subsequent re-infection are of importance for chronic osteomyelitis treatment. The application of bone repair materials with antibacterial properties in such a condition has advantages. The present study reported a novel method to fabricate nanohydroxyapatite/polyurethane (n-HA/PU) based antibacterial porous scaffolds through immobilization "core-shell" silver-based mesoporous silica particles (Ag@SiO₂), i.e., silver nanoparticle as core and mesoporous silica as shell, on the surface of n-HA/PU scaffold. The samples were characterized by Scanning Electron Microscope (SEM) and antibacterial tests. The results revealed that the Ag@SiO₂ nanoparticles distributed uniformly on the surface of n-HA/PU porous scaffold. The Ag@SiO₂ could been kept on the surface of n-HA/PU porous scaffold more than 2 weeks, resulting in long-lasting the release of silver ions and antibacterial ability. The porous n-HA/PU scaffolds with an antibacterial surface may hold promise to be used in infectious bone defects repair.

Abstract: In order to assemble titania nanotubes arrays (TNTs) with better performance in solar cells application, hierarchical voltage-reduction was employed to reduce the thickness of barrier layer and acquire freestanding films simultaneously. Study of intratubular microenvironment and TiO₂/Ti interface indicated that it might be H⁺ generated in anodizing process permeating into the Ti substrate that resulted in peeling off the whole tube layers. Our findings provide a promising way to fabricate freestanding TNTs membranes just by tailoring the applied voltage.

Abstract: The glycerides of castor oil (GCO) were copolymerized with isophorone diisocyanate (IPDI) to generate glyceride-based polyurethane (GCPU), meanwile blending with hydroxyapatite (HA) powder to fabricate porous composite scaffolds. The effect of HA content on mechanical properties of the resulting polymer scaffolds and the in vitro cell response of HA/GCPU scaffolds were investigated, by use of mechanical testing, FTIR, SEM and MTT assay. The results showed that the compressive strength increased with HA content, and the HA/GCPU scaffold with 40 wt% HA reached about 4.6 MPa, much higher than the scaffold without HA (only 605 kPa). The SEM observation, live-dead staining assay and MTT assay demonstrated the excellent biological properties of HA/GCPU scaffolds, which support cell adhesion and proliferation. This novel class of HA/GCPU porous scaffolds have prospect and advantage for bone repair and regeneration.

Abstract: In this paper, isoniazid (INH)-loaded poly (ε-caprolactone) microspheres with a special microporous surface and relatively high drug loading were fabricated by an oil-in-oil (O/O) solvent evaporation method. Meanwhile the microspheres were produced by an oil-in-water (O/W) method for comparison. The technological parameters such as the concentration of surfactant, the volume of continuous phase and the quantity of the drug were investigated systematically. The microspheres morphology, their size distribution and the viscosity of both the dispersed and continuous phase were characterized. The results indicate that the O/O solvent evaporation method is a feasible approach to encapsulate micromolecular and hydrophilic drugs in PCL. This opens the door for INH-loaded microspheres able to release drugs and thereby improve the therapy of tuberculosis of bones and joints in the future.

Abstract: Acicular nano-hydroxyapatite (n-HA) was used to make a new biomaterial composite with polycarbonate by a novel technique. The physical and chemical characteristics of the composites were tested. It was found that the synthesized n-HA crystals were similar to bone apatite in size, phase composition and crystal structure. The TEM results indicated the biomimetic n-HA crystals were uniformly distributed in the polymer matrix. Chemical inter-action between inorganic n-HA and polycarbonate was investigated and discussed. These results indicate that the composite fulfills the basic requirement of bone substitute material, and has the potential for clinical applications.

Abstract: In the paper, ampicillin-loaded alginate(ALG) microspheres covered with chitosan (CS) were firstly prepared by emulsification/internal gelation method. These microspheres were mixed with n-HA/CS composite and then were fabricated into porous scaffold carrying micropheres by gas-foaming together with phase-separation. their properties were characterized by the methods of scanning electronic microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and inversed microscope. The drug releasing rate and entrapment efficiency were tested by spectrophotometry at 203 nm. The results show that the porous scaffold carrying microspheres has good property of slow drug releasing rate. The research will offer a new kind of degradable porous scaffold with good property of controlled drug release for bone or cartilage repairing.

Abstract: Scaffold in bone tissue engineering must have a three-dimensional (3-D) interconnected porous structure acting as a template for bone tissue regeneration, and material fabricating the scaffold must be biocompatible and can provide structural support during bone growth and remodeling at the same time. In this paper, a method of phase separation and particle leaching combined (PS/PL) was used to prepare porous scaffold of nano-hydroxyapatite and polyamide6 (n-HA/PA6) composite. The results show that the scaffold prepared by PS/PL has not only interconnected macropores of 100~300 μm, but also micropores on the walls of macropores, and PS/PL scaffold is more interconnective in compare with phase separation (PS) scaffold. When the porosity of the scaffold is about 79%, its compressive strongth is about 3.27 MPa, that is similar to the human cancellous bone(2~10MPa). Ethanol has some effect on hydrogen bonds, but fabricating method will not change the chemical component of the composite. The porous scaffold is prospect for bone tissue engineering.

Abstract: A novel nano-hydroxyapatite/chitosan (n-HA/CS) composite scaffold with high porosity was developed by a new method of emulsion-foaming/freeze-drying process and was characterized by means of infrared spectroscopy (IR), scanning electronic microscopy (SEM) and universal material testing machine. In addition, the porosity and density of the scaffold were also calculated. IR result shows that the characteristic absorption peaks belonging to both CS and HA are present in their composite, and the slight band-shifts and peak-decrease suggest that some interactions have taken place between the two phases of CS and n-HA in the composite. SEM photo displays that, with the dosage increase of Tween-80, the prepared scaffold shows highly porous and interconnected structure, in which macropores and micropores coexist. The calculated data demonstrate that the porosity of the scaffold is proportional to the content of the emulsifier, while the compressive strength is inversely. When 15wt% emulsifier used, the porosity of the scaffold can be up to 90% and the density is 0.453g/cm3, while the corresponding compressive strength is about 2.4MPa. The newly developed n-HA/CS composite scaffolds may serve as a good 3-D substrate for cell attachment and migration in bone tissue engineering.

Abstract: Nano-hydroxyapatite/polyamide66 (n-HA/PA66) composite scaffolds are prepared using phase separation and phase separation in combination with particle leaching, and both the composite powder and paste are used as starting materials. The composite is characterized by IR and XRD. The micro-architecture of the scaffolds is observed by SEM, and the mechanisms that the formation of the porous structure follows have been investigated preliminarily. The results show that scaffold prepared by phase separation in combination with particle leaching method using composite powder as starting material possesses controllable porosity and interconnectivity, as well as good mechanical strength comparable to human cancellous bone, suitable for being the tissue-engineered scaffold for load-bearing bone repair. Furthermore, scaffold made by phase separation using composite paste as starting material exhibits an anisotropy both in morphology and mechanical properties, which indicates the potential of guiding cell seeding, distribution and new tissue formation in preferential direction.