Qing Cai

Beijing University of Chemical Technology, Peping, Beijing, China

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Publications (52)98.09 Total impact

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    ABSTRACT: Biodegradable polyesters and polyphosphazenes are both promising biomaterials for tissue regeneration. A combination of both materials would provide additional advantages over the individual components in aspects of biocompatibility and osteocompatibility. Applications of polyester/polyphosphazene composites, however, were limited due to the severe phase separation. In this study, cross-linkable poly(glycine ethyl ester-co-hydroxyethyl methacrylate)phosphazene (PGHP) was synthesized. It was blended with poly(L-lactide) (PLLA) or poly(L-lactide-co-glycolide) (PLGA), using chloroform as a mutual solvent, and photo-crosslinked before solvent removal. The resulting PLLA (or PLGA)/PGHP composites demonstrated no significant phase separation due to the restricting function of the crosslinked PGHP polymeric network. In comparison with uncrosslinked blends, the mechanical properties of crosslinked composites were remarkably improved, which indicated their strong potential in bone regeneration applications.
    Biomedical Materials 12/2014; 9(6):061001. · 2.92 Impact Factor
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    ABSTRACT: Substrate-controlled mineralization from simulated body fluid (SBF) has been studied as a model for biomineralization and for the synthesis of bioinspired hybrid materials. The mineralization procedure is complex and the features of final minerals are affected by many factors. Surface functional groups are among them and play important roles in inducing nucleation, crystal growth and transformation. In this study, multi-walled carbon nanotubes (MWCNTs) were surface-modified with poly(acrylic acid), polyacrylamide or poly(hydroxyethyl methylacrylate), and used as templates for biomineralization. The polymer coating was gained via photo-initiated polymerization of monomers and adsorption of polymer chains onto MWCNTs in solution. Then, the modified MWCNTs with different surface functional groups were incubated in 1.5 times SBF for different times to compare the effect of carboxyl, acylamino and hydroxyl group on calcium phosphate formation. The study involved various characterizations such as morphology observation, weight increase, chemical and crystal structures of deposited minerals at different soaking time points. In all cases, carbonated calcium-deficient hydroxyapatite (CDHA) was identified after 7 days immersion. The continuously growing mineral crystals would wrap MWCNTs into spherical composite particles ultimately. However, the rates of nucleation and crystal growth depended on the type of surface functional groups, in an order of COOH>CONH2>OH. And their different charge characteristics led to different Ca/P ratios in initially formed minerals. It revealed that acylamino group, which demonstrated the lowest Ca/P ratio in nucleation stage, was helpful to obtain c-axis preferentially oriented morphology resembling the HA structure in natural bone tissue. Copyright © 2014 Elsevier B.V. All rights reserved.
    Colloids and surfaces B: Biointerfaces 10/2014; · 4.28 Impact Factor
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    ABSTRACT: In this study, a strategy of using iodine-containing cyclophosphazenes as radiopacifiers for dental composite resin was evaluated. It was hypothesized that cyclophosphazenes bearing both iodine and acrylate group swere able to endow composite resins radiopacity without compromising mechanical properties. The cyclophosphazene compounds were synthesized by subsequently nucleophilic substitution of hexachlorocyclotriphosphazene with hydroxyethyl methacrylate (HEMA) and 4-iodoaniline. Cyclotriphosphazenes containing two different molar ratios of HEMA to 4-iodoaniline (1:5 and 2:4) were obtained, and were identified with (1)H NMR, FT-IR, UV and mass spectroscopy. The iodine-containing cyclophosphazenes were able to dissolve well in bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) resin, and were added at two contents (10 or 15%wt. of the resin). The resins were photo-cured and post-thermal treated before characterizations. The resulting composite resins demonstrated the ability of blocking X-ray. And the addition of HEMA-co-iodoaniline substituted cyclotriphosphazenes caused minor adverse effect on the mechanical properties of the resins because the cyclotriphosphazenes could mix well and react with the resins. The presence of rigid phosphazene rings between resin backbones displayed an effective function of decreasing polymerization shrinkage. In summary, soluble and reactive iodine-containing cyclotriphosphazenes demonstrated advantages over traditional heavy metals or metal oxides in being used as additives for producing radiopaque dental resins.
    Materials Science and Engineering C 10/2014; 43C:432-438. · 2.74 Impact Factor
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    ABSTRACT: Carbon nanomaterials (CNM), such as carbon nanotube (CNT) and graphene, are highlighted in bone regeneration because of their osteo-inductive properties. Their combinations with nanofibrous polymeric scaffolds, which mimic the morphology of natural extracellular matrix of bone, arouse keen interest in bone tissue engineering. To this end, CNM were incorporated into nanofibrous poly(L-lactic acid) (PLLA) scaffolds by thermal induced phase separation. The CNM-containing composite nanofibrous scaffolds were biologically evaluated by both in vitro co-culture of bone mesenchymal stem cells (BMSCs) and in vivo implantation. The nanofibrous structure itself demonstrated significant enhancement in cell adhesion, proliferation and oseogenic differentiation of BMSCs, and with the incorporation of CNM, the composite nanofibrous scaffolds further promoted osteogenic differentiation of BMSCs significantly. Between the two CNMs, graphene showed stronger effect in promoting osteogenic differentiation of BMSCs than CNT. The results of in vivo experiments revealed that the composite nanofibrous scaffolds had both good biocompatibility and strong ability in inducing osteogenesis. CNMs could remarkably enhance the expression of osteogenesis-related proteins as well as the formation of type I collagen. Similarly, the graphene-containing composite nanofibrous scaffolds demonstrated the strongest effect on inducing osteogenesis in vivo. These findings demonstrated that CNM-containing composite nanofibrous scaffolds were obviously more efficient in promoting osteogenesis than pure polymeric scaffolds.
    Journal of Biomedical Materials Research Part A 07/2014; · 2.83 Impact Factor
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    ABSTRACT: A kind of core-shell nanofibers containing sodium fluoride (NaF) was produced and used as reinforcing materials for dimethacrylate-based dental restorative resins in this study. The core-shell nanofibers were prepared by coaxial-electrospinning with polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) solutions as core and shell fluids, respectively. The produced PAN-PMMA nanofibers varied in fiber diameter and the thickness of PMMA shell depending on electrospinning parameters. NaF-loaded nanofibers were obtained by incorporating NaF nanocrystals into the core fluid at two loadings (0.8 or 1.0wt.%). Embedment of NaF nanocrystals into the PAN core did not damage the core-shell structure. The addition of PAN-PMMA nanofibers into Bis-GMA/TEGDMA clearly showed the reinforcement due to the good interfacial adhesion between fibers and resin. The flexural strength (Fs) and flexural modulus (Ey) of the composites decreased slightly as the thickness of PMMA shell increasing. Sustained fluoride releases with minor initial burst release were achieved from NaF-loaded core-shell nanofibers and the corresponding composites, which was quite different from the case of embedding NaF nanocrystals into the dental resin directly. The study demonstrated that NaF-loaded PAN-PMMA core-shell nanofibers were not only able to improve the mechanical properties of restorative resin, but also able to provide sustained fluoride release to help in preventing secondary caries.
    Materials science & engineering. C, Materials for biological applications. 01/2014; 34C:262-269.
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    ABSTRACT: Objective The objective of this study was to prepare a novel asymmetric chitosan guided bone regeneration (GBR) membrane, which is composed of a dense layer isolating the bone defect from the invasion of surrounding connective fibrous tissue and a loose layer which can improve cell adhesion and stabilize blood clots, thus guided bone regeneration. Methods The chitosan membrane was fabricated through liquid nitrogen quencher combined with lyophilization and cross-linked by sodium tripolyphosphate (TPP). The physical properties of asymmetric chitosan membrane were measured by scanning electron microscope (SEM), fourier-transform infrared (FTIR), x-ray diffraction (XRD) and tensile test machine. MTT assay and Live/Dead cell staining for MC3T3-E1 osteoblasts cultured on the membrane were used to characterize the biocompatibility of the membrane. In animal experiments, full-thickness and critical sized skull defects were made to evaluate the effect of the membrane on bone regeneration. Results The results of this study indicate that the asymmetric chitosan membrane can be built and cross-linked by TPP to enhance the tensile strength of the membrane. In vitro experiment showed that no significant numbers of dead cells were detected on the chitosan membrane, indicating that the membrane had good biocompatibility. In animal experiments, the chitosan membrane had faster new bone formation, showing the capability to enhance bone regeneration. Conclusion The chitosan membrane prepared in this study has an asymmetric structure; its tensile strength, biodegradation and biocompatibility fulfill the requirements of guided bone regeneration. Therefore, the asymmetric chitosan membrane is a promising GBR membrane for bone regeneration. Clinical Significance Guided bone regeneration (GBR) is an effective method for healing bone defects caused by periodontitis and implantitis, in which GBR membrane is a key biomaterial.
    Journal of Dentistry. 01/2014;
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    ABSTRACT: Biodegradable polyphosphazenes were categorized as osteoinductive materials due to their phosphorus-containing feature, however, they were less supportive in cell attachment and proliferation at earlier points in comparison with biodegradable aliphatic polyesters. Therefore, mussel-inspired surface modification of poly(alanine ethyl ester -co- glycine ethyl ester)phosphazene (PAGP) was studied, intending to circumvent the above mentioned disadvantage of polyphosphazene. To this end, PAGP and poly(L-lactide) (PLLA) were electrospun into nanofibrous substrates and surface treated with dopamine aqueous solution. With the analysis of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscope (XPS) and Fourier transform infrared spectroscope (FT-IR), the successful poly(dopamine) coating was identified on both PAGP and PLLA nanofibers. MC3T3-E1 osteoblasts were found attaching and proliferating much well on poly(dopamine) modified nanofibrous substrates in comparison with the pristine ones. Besides, the poly(dopamine) coating demonstrated high activity in promoting osteogenous differentiation. Because the phosphorus content on nanofiber surface was decreased with the poly(dopamine) coating, the poly(dopamine)-coated PAGP nanofibrous substrate was slightly inferior to pure PAGP nanofibrous substrate in osteogenous differentiation. In a summary, the results confirmed that poly(dopamine) modified polyphosphazenes were promising scaffold materials with both high cell affinity and high osteocompatibility for bone regeneration.
    Journal of Biomedical Materials Research Part A 12/2013; · 2.83 Impact Factor
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    ABSTRACT: Composite nanofibers composed of polyacrylonitrile (PAN)-based carbon nanofibers and bioactive glass (BG) nanoparticles have been prepared by electrospinning and in situ sintering. Morphology observation showed that the BG nanoparticles of size 20-50 nm were uniformly distributed on the surface of composite nanofibers with 350 nm average diameter after carbonization. Biological mineralization indicated the formation of apatite-like layer on the surface of composite nanofibers, in which the composition of carbonate hydroxyapatite was proved by FTIR and XRD analysis. Cell growth dynamics according to cellular morphology, CCK-8 assay, and alkaline phosphatase activity assay exhibited better cell adhesion, proliferation, and osteogenic induction of bone marrow-derived mesenchymal stem cells cultured on the composite nanofibers, which suggested the higher bioactivity of composite nanofibers compared to pure PAN-based carbon nanofibers.
    Journal of Biomaterials Science Polymer Edition 11/2013; · 1.70 Impact Factor
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    ABSTRACT: The nanotopographical features of artificial scaffolds have complex effects on the biological characteristics of stem cells. They influence cell adhesion, spreading, proliferation, and differentiation; however we have limited knowledge on how these processes occur under nanotopographical cues. In this study, two kinds of electrospun nanofibrous meshes with different fiber arrangements (totally non-woven and lattice-like) were fabricated and used for in vitro culture of mesenchymal stem cells (MSCs). By comparing the characteristic marks related to osteogenic differentiation, we found that with prolonged culture time, osteopontin (OPN), osteocalcin (OCN) and alkaline phosphatase (ALP), as well as related genes (Runx2 and Colla genes), were all expressed at higher levels on lattice-like nanofibrous meshes than on non-woven ones. These results indicated that the lattice-like nanofibrous mesh activated the osteogenic differentiation of MSCs owing to changes in cell morphology directed by nanofiber orientations. Compared with pure non-woven nanofibrous meshes, lattice-like ones possessed a combined structure of parallel, magnetic-line-like, and non-woven regions. MSCs adhering onto them had upregulated expression levels of integrin subunits a5 and b1, and activated downstream signaling pathways of Ras homolog gene family member A (RhoA) and extracellular signal-regulated kinase (ERK). When the specific inhibitors PD98059 and Y27632 were used to inhibit phosphorylated ERK and p160 ROCKII activity, respectively, F-actin became disordered and the expression level of Runx2 was downregulated. Thus, we concluded that the scaffold nanotopography may modulate the microenvironment of MSCs and promote their osteogenic differentiation through the RhoA and ERK signaling pathways. These findings provided valuable information on the selection of artificial matrices suitable for MSCs application in bone tissue engineering.
    Journal of Biomedical Nanotechnology 10/2013; 9(10):1757-67. · 7.58 Impact Factor
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    ABSTRACT: Magnetic poly(l-lactide) (PLLA)/Fe3O4 composite nanofibers were prepared with the purpose to develop a substrate for bone regeneration. To increase the dispersibility of Fe3O4 nanoparticles (NPs) in the PLLA matrix, a modified chemical co-precipitation method was applied to synthesize Fe3O4 NPs in the presence of PLLA. Trifluoroethanol (TFE) was used as the co-solvent for all the reagents, including Fe(II) and Fe(III) salts, sodium hydroxide, and PLLA. The co-precipitated Fe3O4 NPs were surface-coated with PLLA and demonstrated good dispersibility in a PLLA/TFE solution. The composite nanofiber electrospun from the solution displayed a homogeneous distribution of Fe3O4 NPs along the fibers using various contents of Fe3O4 NPs. X-ray diffractometer (XRD) and vibration sample magnetization (VSM) analysis confirmed that the co-precipitation process had minor adverse effects on the crystal structure and saturation magnetization (Ms) of Fe3O4 NPs. The resulting PLLA/Fe3O4 composite nanofibers showed paramagnetic properties with Ms directly related to the Fe3O4 NP concentration. The cytotoxicity of the magnetic composite nanofibers was determined using in vitro culture of osteoblasts (MC3T3-E1) in extracts and co-culture on nanofibrous matrixes. The PLLA/Fe3O4 composite nanofibers did not show significant cytotoxicity in comparison with pure PLLA nanofibers. On the contrary, they demonstrated enhanced effects on cell attachment and proliferation with Fe3O4 NP incorporation. The results suggested that this modified chemical co-precipitation method might be a universal way to produce magnetic biodegradable polyester substrates containing well-dispersed Fe3O4 NPs. This new strategy opens an opportunity to fabricate various kinds of magnetic polymeric substrates for bone tissue regeneration.
    Materials science & engineering. C, Materials for biological applications. 08/2013; 33(6):3498-3505.
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    ABSTRACT: The purpose of this study is to evaluate the effects of surface modification of fiber posts using dopamine polymerization on their interfacial adhesion with core resins. The fiber posts were surface-coated with polydopamine via the oxidization polymerization of dopamine in aqueous solution. Two commercial composite resins (3M ESPE and paracore) were used to build up the cores around the post heads (modified and unmodified). Pull-out tests were conducted, and the maximum failure load (N) and the failure modes were recorded to compare the interfacial adhesion between fiber post and resin core. The results demonstrated that the tensile forces needed to damage the retention of fiber post increased from 228.6 ± 10.9 N to 276.3 ± 14.7 N in the 3M ESPE group, from 216.5 ± 17.4 N to 277.2 ± 14.3 N in the paracore group, when polydopamine-coated fiber posts were applied. No significant difference had been found between the different resin groups. The observation of the surface morphology of both fiber posts and cores after adhesive failure clearly confirmed that the presence of polydopamine interlayer had acted as a binder to bond fiber post and resin together. This study would be valuable for endodontically treatments to reduce the chances of detachment of resin core from the fiber post or dislodgement of fiber posts from the canal.
    Applied Surface Science 06/2013; 274:248–254. · 2.54 Impact Factor
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    ABSTRACT: Biodegradable poly (lactic-co-glycolic acid) (PLGA) microparticles are an effective way to achieve sustained drug release. In this study, we investigated a sustained release model of PLGA microparticles with incorporated protein via either emulsion or coaxial electrospray techniques. PLGA (75:25) was used as the carrier, and bovine serum albumin as a model protein. Coaxial electrospray resulted in a type of core-shell structure with mean diameters of 2.41 ± 0.60 µm and a centralised protein distribution within the core. Emulsion electrospray formed bigger microparticles with mean diameters of 22.75 ± 8.05 µm and a heterogeneous protein distribution throughout the microparticles. The coaxial electrospray microparticles presented a much slighter burst release than the emulsion electrospray microparticles. Loading efficiency was significantly higher (p < 0.05) in the coaxial group than emulsion group. This indicated that both emulsion and coaxial electrospray could produce protein-loaded microparticles with sustained release behaviour, but the former revealed a superior approach for drug delivery.
    Journal of Microencapsulation 01/2013; · 1.57 Impact Factor
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    ABSTRACT: To improve the dispersibility of silica nanoparticles in dimethacrylate-based dental restorative composite resins, an efficient way was proposed to surface modify silica nanoparticles with polymer grafts. Firstly, silica nanoparticles reacted with 3-aminopropyl-triethoxysilane and 2-bromoisobutyryl bromide to obtain silica with the derived atom transfer radical polymerization (ATRP) initiators, which subsequently initiated the polymerization of methyl methacrylate to fabricate poly(methyl methacrylate) grafted silica nanohybrids. These nanohybrids could be well dispersed into bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) resin and had good interfacial bonding to the resin matrix. With the addition of modified silica nanopaticles, the flexural strength of the photo-cured composite resin was significantly increased in comparison with that of the unmodified group.
    Advanced Materials Research. 01/2013; 647:46-52.
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    ABSTRACT: Poly(lactide-co-glycolide) (PLGA) copolymers are the most prevalent materials for tissue engineering applications. To mimic the real microenvironment of extracellular matrix (ECM) for cell growth, nanofibrous PLGA scaffolds are preferred. PLGA5050 (in which the molar ratio of lactidyl to glycolidyl units is 50:50), which is an utterly amorphous polymer, was first reported to be made into nanofibrous networks (fiber diameter around 500 nm) using phase separation from PLGA5050/THF solutions in this study. The concentration of polymeric solution had significant effects on fiber diameter and unit length. Nonsolvent (e.g. H2O) was unnecessary to form the PLGA5050 gel, which was critical to nanofibrosis, as if the environmental temperature for gelation occurrence was low enough (− 70 °C). The physical crosslinks to stabilize the PLGA5050/THF gel were believed to be GA segments along the backbone owing to their inferior solubility in THF. The addition of H2O would cause adverse effects of liquid–liquid phase separation and nanofibrosis failure owing to the hydrophilicity of glycolidyl units. Associating with the phase separation method, particle-leaching technique was applied to fabricate three-dimensional scaffolds with macroporous and nanofibrous structures. To ensure the occurrence of nanofibrosis on macropore walls, the temperature of salt particles should be best lowed to − 70 °C beforehand. Accordingly, scaffolds prepared under varied parameters exhibited different nanofiber and pore morphologies, which affected the pore size, porosity, specific surface area, water contact angle and protein adsorption ability etc. The preliminary cell (MC3T3-E1) culture confirmed the cell ingrowth into the macroporous and nanofibrous PLGA5050 scaffolds in comparison with the solely nanofibrous matrixes. This kind of bi-scaled three dimensional matrixes can be superior candidate scaffolds for tissue engineering applications.
    Materials Science and Engineering: C. 08/2012; 32(6):1407–1414.
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    ABSTRACT: To synthesize polyesters and periodic copolymers catalyzed by nonafluorobutanesulfonimide (Nf2NH), we performed ring-opening copolymerizations of cyclic anhydrides with tetrahydrofuran (THF) at 50–120 °C. At high temperature (100–120 °C), the cyclic anhydrides, such as succinic anhydride (SAn), glutaric anhydride (GAn), phthalic anhydride (PAn), maleic anhydride (MAn), and citraconic anhydride (CAn), copolymerized with THF via ring-opening to produce polyesters (Mn = 0.8–6.8 × 103, Mn/Mw = 2.03–3.51). Ether units were temporarily formed during this copolymerization and subsequently, the ether units were transformed into esters by chain transfer reaction, thus giving the corresponding polyester. On the other hand, at low temperature (25–50 °C), ring-opening copolymerizations of the cyclic anhydrides with THF produced poly(ester-ether) (Mn = 3.4–12.1 × 103, Mw/Mn = 1.44–2.10). NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectra revealed that when toluene (4 M) was used as a solvent, GAn reacted with THF (unit ratio: 1:2) to produce periodic copolymers (Mn = 5.9 × 103, Mw/Mn = 2.10). We have also performed model reactions to delineate the mechanism by which periodic copolymers containing both ester and ether units were transformed into polyesters by raising the reaction temperature to 120 °C. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
    Journal of Polymer Science Part A Polymer Chemistry 08/2012; 50(15):3171-3183. · 3.54 Impact Factor
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    ABSTRACT: It is important to improve the compatibility of hydroxyapatite (HA) nanoparticles in biodegradable polyesters to obtain desirable nanocomposites for bone tissue engineering applications. Polymer grafting has been proven an efficient way to get nanohybrids with good dispersibility in polymeric matrixes. In this paper, a new strategy to prepare HA–poly(l-lactide) (PLLA) nanohybrids was developed, where PLLA oligomers were grafted from HA nanoparticle surfaces via surface-initiated atom transfer radical polymerization (ATRP) of methylacrylate group terminated PLLA macromonomers (PLLA-MA). HA with the derived ATRP initiators was obtained by (1) preparation of HA from precursors in the presence of 3-aminopropyl-triethoxysilane (APTS) to produce the HA surface with terminal NH2 groups (HA–NH2) and (2) reaction of the NH2 groups of the HA–NH2 nanoparticles with 2-bromoisobutyryl bromide (BIBB) to produce the 2-bromoisobutyryl-immobilized nanoparticles (HA–Br). The obtained HA–PLLA nanohybrids demonstrated good dispersibility in chloroform. With the good dispersion of HA–PLLA nanohybrids in PLLA matrix, the resultant PLLA/HA–PLLA nanocomposites could much faster induce bone-like apatite-formation in simulated body fluids (SBF) than the PLLA/HA counterparts where the HA nanoparticles aggregated heavily. With the versatility of ATRP, properly, grafting oligomeric PLLA chains from HA nanoparticle surfaces is an effective means for the design of novel HA–polymer biohybrids for future bone tissue engineering applications.
    Applied Surface Science 07/2012; 258(18):6823–6830. · 2.54 Impact Factor
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    ABSTRACT: Biodegradable amino acid ester-substituted polyphosphazenes are unique biomaterials for tissue engineering. Considering the surface properties as topography and chemical composition having vital roles in regulating cellular response, in this study, a kind of micropatterned polyphosphazene films were prepared and subjected to osteoblasts culture. Briefly, poly(glycine ethyl ester-co-alanine ethyl ester)phosphazene (PGAP) was synthesized, and its solution in chloroform was cast under high (80%) or low (20%) environmental humidity. Honeycomb-patterned or flat PGAP films were resulted. By analyzing with scanning electron microscope, atomic force microscope, X-ray photoelectron spectroscope, and water contact angle measurement, the honeycomb-patterned PGAP films demonstrated higher surface roughness, phosphorous and nitrogen content, and hydrophilicity than the flat one. Although the initial cell attachment and proliferation on PGAP films were inferior to those on conventional poly(lactic-co-glycolic acid) films, P-containing PGAP was a sort of bone-binding bioactive polymer. With these alternations, honeycomb-patterned PGAP films had accordingly enhanced protein adsorption and apatite deposition in simulated body fluid and showed great advantages in promoting osteogenous differentiation. The results suggested a potential way to make polyphosphazenes as good choices for bone tissue regeneration by increasing their surface roughness and phosphorous content. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
    Journal of Biomedical Materials Research Part A 06/2012; · 2.83 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the properties of a novel inorganic xenogenic bone substitute, calcinated antler cancellous bone (CACB). Physicochemical properties of CACB including surface morphology, phase composition, chemical bond structure, Ca/P ratio and porosity were characterized by scanning electron microscopy, X-ray diffraction spectroscopy, Fourier-transform infrared spectroscopy, inductively coupled plasma-atomic emission spectroscopy and nitrogen adsorption analysis, and were found to closely resemble calcinated human cancellous bone. The bone defect repair efficacy of CACB was evaluated in comparison with commercially available bone substitutes (Bio-Oss(®)) within rabbit mandible defects. The gross observation, micro-CT and histology analysis data demonstrated that CACB was efficacious for bone regeneration, and was comparable with Bio-Oss(®) bone substitute in inducing neovascularization and osteogenesis within the mandible defects. CACB can therefore serve as a safe, renewable, and sustainable source of bone graft material, but without the ethical issues pertaining to animal welfare.
    International Journal of Oral and Maxillofacial Surgery 06/2012; 41(11):1330-7. · 1.52 Impact Factor
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    ABSTRACT: The ability to manipulate and control the surface properties of hydroxyapatite (HA) nanoparticles is of crucial importance for the design of HA-based carriers of therapeutic agents. In this work, surface-initiated atom transfer radical polymerization (ATRP) of (2-dimethyl amino)ethyl methacrylate (DMAEMA) is first employed to tailor the functionality of HA surfaces in a well-controlled manner and to produce a series of new cationic hybrids (termed as HA-PDM). The HA parts of HA-PDM were coated by different lengths of PDMAEMA chains. The HA-PDM exhibited a good ability to condense plasmid DNA (pDNA) with suitable particle size and a zeta potential for gene transfection. Most importantly, in comparison with PDMAEMA homopolymers, the HA-PDM displayed considerably enhanced buffering capacity, and exhibited much higher gene transfection efficiencies in different cell lines, including osteoblast MC3T3 and osteosarcoma MG63 cells. In addition, the HA-PDM/pDNA complexes also could largely enhance the differentiation of preosteoblast cells. Such well-defined HA-PDM nanohybrids possess great potential applications as new drug-delivery vectors in bone tissue engineering.
    Journal of Materials Chemistry 04/2012; 22(18):9358-9367. · 6.63 Impact Factor
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    ABSTRACT: The Peptidyl arginine deiminase, type IV (PADI4) gene has been suggested to have an association with rheumatoid arthritis (RA) in several populations. But its role in Chinese RA is not clarified. We investigated five single-nucleotide polymorphisms (SNPs) of PADI4 as PADI4-89 (rs11203366), PADI4-90 (rs11203367), PADI4-92 (rs874881) PADI4-94 (rs2240340), and PADI4-104 (rs1748033) in Chinese Han population. A total of 378 unrelated RA patients and 204 healthy controls were genotyped for the five SNPs. Individual allele, genotype and haplotype frequencies were compared between patients and controls. No significant differences in the frequency of PADI4 alleles, genotypes and haplotypes were observed between the patients and controls except PADI4-92. These data indicated that PADI4 polymorphisms were unlikely to play an important role in the susceptibility to RA in Chinese Han population.
    Rheumatology International 12/2011; 31(12):1631-4. · 2.21 Impact Factor

Publication Stats

127 Citations
98.09 Total Impact Points


  • 2004–2014
    • Beijing University of Chemical Technology
      • College of Materials Science and Engineering (SMSE)
      Peping, Beijing, China
  • 2011–2013
    • Peking University School of Stomatology
      Peping, Beijing, China
  • 2008–2011
    • Second Military Medical University, Shanghai
      Shanghai, Shanghai Shi, China
    • Peking University
      Peping, Beijing, China
  • 2006–2011
    • Changhai Hospital, Shanghai
      Shanghai, Shanghai Shi, China