Daping Quan

Sun Yat-Sen University, Shengcheng, Guangdong, China

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Publications (38)131 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel, biocompatible and biodegradable six-arm branched copolymer poly(d,l-lactide)-co-(1,3-trimethylene carbonate)6 has been synthesized and fabricated as a porous microparticle with an oil-in-water single emulsion method. Poly(d,l-lactide-co-1,3-trimethylene carbonate)6 microparticles were further conjugated with heparin by 1-ethyl-3-3-dimethylamino-propylcarbodiimide/N-hydroxysuccinimide chemistry and characterized using 1H-nuclear magnetic resonance and scanning electron microscopy. The heparin-loading capacity of poly(d,l-lactide-co-1,3-trimethylene carbonate)6 microparticles was identified as 213 ± 6 pmol/mg-particle determined with toluidine blue method. The resultant binding efficiency and release profile of basic fibroblast growth factor which is bound on heparin-poly(d,l-lactide-co-1,3-trimethylene carbonate)6 microparticles were quantitatively analyzed by enzyme-linked immunosorbent assay. Thus, the developed poly(d,l-lactide-co-1,3-trimethylene carbonate)6 porous microparticles presented superior capacity of growth factor cargo as 1965 ± 117 pg basic fibroblast growth factor per mg-microparticles and displayed a sustained release profile over 4 weeks with quite low initial burst. Additionally, the viability of dissociated basic fibroblast growth factor was confirmed with methylthiazolyltetrazolium quantitative assay along with in vitro culturing model of rodent neural stem cell. Collectively, our results demonstrate that heparin-poly(d,l-lactide-co-1,3-trimethylene carbonate)6 microparticles attained controllable and sustained delivery of bioactive basic fibroblast growth factor for 4 weeks with significantly reduced burst release. The present heparin-poly(d,l-lactide-co-1,3-trimethylene carbonate)6 porous microparticulate system could be potentially developed to foster a novel bioengineering platform for repair and regeneration of injured nervous system.
    No preview · Article · Jul 2015 · Journal of Bioactive and Compatible Polymers
  • Tao Wang · Mingfa Yan · Xiumin Sun · Daping Quan
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    ABSTRACT: The design and synthesis of a novel polyether-ester injectable hydrogel with a low gelation concentration and biological compatibility is important in tissue engineering. PTMC-F127-PTMC and PTMAc-F127-PTMAc block copolymers were synthesised via the ring-opening polymerisation of trimethylene carbonate (TMC) or copolymerisation of TMC and 2-methyl,2-methylacrylate,1,3-bimethylene (Ac) using F127 as the macro-initiator, and the structure was confirmed using 1H NMR and GPC. The properties of the diluted copolymer solution were studied via 1H NMR, a pyrene-fluorescence probe method and dynamic light scattering. The results showed that the introduction of short-chain polycarbonate decreased the critical micelle concentration (CMC) of the copolymer by an order of magnitude and significantly increased the diameter of the aggregate particles compared with the F127. Furthermore, the introduction of PAc segments increased this tendency. The gelation behaviour of the copolymer solution showed that this polyether-ester polymer hydrogel still retained the characteristics of the thermo-sensitive Sol-Gel transition, and the critical gelation concentration (CGC) decreased to 4-6% (15% was achieved using only F127). A physical-chemical dual-crosslinked hydrogel was fabricated using a quantitative Michael addition reaction between the double bonds in the PTMAc-F127-PTMAc copolymer and the thiols in dithiothreitol (DTT). The storage modulus (G′) of this dual-crosslinked hydrogel was three times greater than that of the simple physical crosslinked hydrogel (from 200 Pa to 630 Pa). Degradation experiments in vitro showed that the mass loss of the dual-crosslinked hydrogel at eight weeks was 20% compared with greater than 50% in the purely physically crosslinked sample. After further enhancements using the RGDC peptide, the PTMAc-F (function() { var scriptTag = document.createElement('script'); scriptTag.type = 'text/javascript'; scriptTag.async = true; scriptTag.src = '//cdn.optimizely.com/js/700600469.js'; var head = document.getElementsByTagName('head')[0]; head.parentNode.insertBefore(scriptTag, head); })(); function optimizelyTimeout() { window.optimizely = window.optimizely|| []; if(!window.optimizely.data) { window.optimizely.push("timeout"); } } setTimeout(optimizelyTimeout, 1000); Article Page — ScienceDirect (function(w, d, c) { if ("querySelector" in d && "addEventListener" in w) { c = d.documentElement.className.replace(/nojs/, 'js hide-article-information') if (document.implementation.hasFeature("http://www.w3.org/TR/SVG11/feature#Image", "1.1")) { c = c.replace(/nosvg/, 'svg'); } d.documentElement.className = c; } })(window, document);
    No preview · Article · Jan 2015 · Polymer
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    ABSTRACT: In this study, a biodegradable thermo-sensitive hydrogel from poly(trimethylene carbonate)15-F127-poly(trimethylene carbonate)15 (PTMC15-F127-PTMC15) was designed and evaluated as an injectable implant during ocular glaucoma filtration surgery in vivo and in vitro. Mitomycin C (MMC) was loaded into this hydrogel for controlled released to prolong the efficacy and to reduce the long-term toxicity. The properties of the hydrogel were confirmed using 1H NMR and gel permeation chromatography (GPC). Compared to the Pluronic F127 hydrogel, the PTMC15-F127-PTMC15 hydrogel showed a good solution-gel transition temperature at 37°C, a lower work concentration of 5% w/v and a longer mass loss time of more than 2 weeks. The in vitro study showed that the drug could be released from PTMC15-F127-PTMC15 (5% w/v) hydrogel for up to 16 days with only 57% of drug released in the first day. Moreover, the cell toxicity, which was tested via LDH and ANNEXIN V/PI, decreased within 72 h in human tenon's fibroblast cells (HTFs). The in vivo behavior in a rabbit glaucoma filtration surgery model indicated that this hydrogel loaded with 0.1 mg/ml MMC led to a better functional bleb with a prolonged mean bleb survival time (25.5±2.9 days). The scar tissue formation, new collagen deposition and myofibroblast generation appeared to be reduced upon histological and immunohistochemistry examinations, with no obvious side effects and inflammatory reactions. The in vitro and in vivo results demonstrated that this novel hydrogel is a safe and effective drug delivery candidate in ocular glaucoma surgery.
    Full-text · Article · Jun 2014 · PLoS ONE
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    ABSTRACT: Since the introduction of the detachable coil in endovascular treatment of intracranial aneurysms, the in-hospital mortality rate has been significantly decreased. Recurrence of the aneurysm remains the major drawback of using detachable coils. We prepared a bioactive coil coated with poly(d,l-lactide)-7co-(1,3-trimethylene carbonate) (P(DLLA-co-TMC)), a novel copolymer for controlling the release of vascular endothelial growth factor (VEGF). Platinum coils were prepared by successive coating with cationic P(DLLA-co-TMC) and anionic heparin. Then, recombinant human VEGF-165 (rhVEGF) was immobilized by affinity binding to heparin. The morphological characteristics and sustained in vitro release of rhVEGF were examined using scanning electron microscopy and enzyme-linked immunosorbent assay, respectively. The efficacy of these novel coils modified by P(DLLA-co-TMC)/rhVEGF was tested using a common carotid artery aneurysm model in rats. Experimental aneurysms were embolized with unmodified, P(DLLA-co-TMC)/heparin-coated or P(DLLA-co-TMC)/rhVEGF-coated platinum coils (n = 18). The coils were removed on days 15, 30 and 90 after insertion, and the histological and immunohistochemical analysis of factor VIII was performed to confirm the presence of endothelial cells in the organized area. In addition, the controlled in vivo release of VEGF was confirmed by Western blotting analysis. The release of VEGF tended to increase during the whole period and no burst release was observed. In the group treated with P(DLLA-co-TMC)/rhVEGF-coated platinum coils, clot organization and endothelial cell proliferation were accelerated. The immunohistochemistry study showed that the expression of factor VIII was found in the P(DLLA-co-TMC)/rhVEGF-coated coil group but not in the other two groups. Furthermore, Western blotting analysis confirmed that the major released VEGF in the aneurysm sac was from the P(DLLA-co-TMC)/VEGF-coated coil. P(DLLA-co-TMC)/rhVEGF-coated platinum coils can promote clot organization and endothelial cell proliferation in a rat aneurysm model.
    No preview · Article · Jun 2014 · Biomedical Materials
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    ABSTRACT: Acellular nerve allografts (ANAs) behave similarly to autografts in supporting axonal regeneration in the repair of short peripheral nerve defects but fail in larger defects. The objective of this paper is to evaluate the effect of ANA supplemented with platelet-rich plasma (PRP) to improve nerve regeneration after surgical repair and to discuss the mechanisms that underlie this approach. Autologous PRP was obtained from rats by double-step centrifugation and was characterized by determining platelet numbers and the release of growth factors. Forty-eight Sprague-Dawley rats were randomly divided into four groups (12/group), identified as autograft, ANA, ANA loaded with PRP (ANA+PRP) and ANA loaded with platelet-poor plasma (PPP, ANA+PPP). All grafts were implanted to bridge long-gap (15 mm) sciatic nerve defects. We found that PRP with a high platelet concentration exhibited a sustained release of growth factors. Twelve weeks after surgery, the autograft group displayed the highest level of reinnervation, followed by the ANA+PRP group. The ANA+PRP group showed a better electrophysiology response for amplitude and conduction velocity than the ANA and ANA+PPP groups. Based on histological evaluation, the ANA+PRP and autograft groups had higher numbers of regenerating nerve fibers. qRT-PCR demonstrated that PRP boosted expression of neurotrophins in the regenerated nerves. Moreover, the ANA+PRP and autograft groups showed excellent physiological outcomes in terms of the prevention of muscle atrophy. In conclusion, ANAs loaded with PRP as tissue-engineered scaffolds can enhance nerve regeneration and functional recovery after the repair of large nerve gaps nearly as well as autografts.
    Preview · Article · Jun 2014 · Tissue Engineering Part A
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    ABSTRACT: Purpose: The aim of this study is to investigate whether CS-g-MMCs conjugate (CSM) could be a new agent to prevent the post-operative fibrosis in a rabbit model of experimental glaucoma filtration surgery. Materials and methods: In a randomized, controlled, masked-observer study, 40 New Zealand White rabbits underwent trabeculectomy in the right eyes and randomly received subconjunctival injection of phosphate buffered saline, chitosan (CS), CSM (100 µg/ml), CSM (200 µg/ml) or Mitomycin C (100 µg/ml). Bleb characteristics and anterior chamber depth were evaluated by slit-lamp examination. The animals were killed on day 14 and 28. Histopathology and immunohistochemistry were performed to determine the amount of the scarring and fibrosis. Ocular toxicity was assessed by histopathology and electron microscope. Results: We found that the five groups were similar with respect to intraocular pressure and anterior chamber depth. The medians for survival days were: 5.5, 8, 17.5, 28 and 16 in the PBS, CS, CSM100, CSM200 and MMC groups, respectively. Both the CSM200 and the MMC group showed a significantly larger bleb area than the CSM100, CS and the PBS group. Less scarring was seen on day 14 and 28 in CSM200 and MMC group than in the PBS, CS and CSM100 group by histology and immunohistochemistry assessment. No damages were found in the rabbit eyes in each group. Conclusions: Subconjunctival injection of CSM postoperatively can improve the filtration bleb survival in the rabbit model. It can be a safe and effective antimetabolite in glaucoma surgery.
    No preview · Article · Apr 2014 · Current eye research
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    ABSTRACT: This study is to test the efficacy of stromal cell-derived factor-1α (SDF-1α)-coated coils together with endothelial progenitor cells (EPCs) transplantation in occluding aneurysms. Bone marrow-derived EPC surface markers were analyzed using flow cytometry. The migratory function of EPCs in response to SDF-1α was evaluated using a modified Boyden chamber assay. Capillary-like tube formation was assessed using Matrigel gel. Coil morphologies before and after coating with SDF-1α were observed under a scanning electron microscope. The level of SDF-1α in supernatants was measured by ELISA. Sprague-Dawley rats were randomly allocated into five groups. Histological analysis was performed on days 14 and 28 after coil implantation. The bone marrow-EPCs could express CD133, CD34, and VEGFR-2 and form tubule-like structures in vitro. Migratory ability of EPCs in the presence of SDF-1α-coated coils was similar to that in the presence of 5 ng/ml SDF-1α gradient. Sustained release of SDF-1α was achieved using silk fibroin as a carrier. In SDF-1α-coated coils + EPCs transplantation group, a well-organized fibrous tissue bridging the orifice of aneurysms was shown on days 14 and 28. On day 28, tissue organization was greater in the SDF-1α-coated coils group than in the unmodified coils group. Immunofluorescence showed α-smooth muscle actin-positive cells in organized tissue in sacs. Combined treatment with SDF-1α-coated coils and EPCs transplantation is a safe and effective treatment for rat aneurysms. This may provide a new strategy for endovascular therapy following aneurysmal subarachnoid hemorrhage.
    No preview · Article · Jan 2014 · International journal of clinical and experimental pathology
  • Chen-Guang Zeng · Yi Xiong · Gaoyi Xie · Peng Dong · Daping Quan
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    ABSTRACT: Nerve conduits (NCs) with multiple longitudinally aligned channels, being mimicking the natural nerves anatomic structure, have been attracted more and more attentions. However, some specific structural parameters of a conduit that would be beneficial for further improvement of neural tissue regeneration were not comprehensively considered. Using a systematized device and combining low-pressure injection molding and thermal induced phase separation (TIPS), we fabricated 33-channel NCs (outer diameter 3.5 mm, channel diameter 200 μm) with different well-defined microscopic features, including a nanofibrous microstructure (NNC), a spherical porous microstructure (MNC) and a ladder-like microstructure (LNC). The porosities of these NCs were approximately 90% and were independent of the fine microstructures, while the pore size distributions were clearly distinct. The adsorption of bovine serum albumin (BSA) for the NNC was a result of having the highest specific surface area, which was 3.5 times that of the LNC. But the mechanical strength of NNC was lower than that of two groups, because of a relative high crystallinity and brittle characteristics. In vitro nerve stem cells (NSCs) incubation revealed that 14 days after seeding the NSCs, 31.32% cells were Map2 positive in the NNC group, as opposed to 15.76% in the LNC and 23.29% in the MNC groups. Addition NGF into the culture medium, being distinctive specific surface area and a high adsorption of proteon for NNC, 81.11% of neurons derived from the differentiation of the seeded NSCs was obtained. As a result of imitating the physical structure of the basement membrane of the neural matrix, the nano-fibrous structure of the NCs has facilitated the differentiation of NSCs into neurons.
    No preview · Article · Oct 2013 · Tissue Engineering Part A
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    ABSTRACT: Introducing concentration gradients of nerve growth factor (NGF) into conduits for repairing of peripheral nerve injury is crucial for nerve regeneration and guidance. Herein, combining differential adsorption of NGF/silk fibroin (SF) coating, the gradient of NGF-immobilized membranes (G-Ms) and nanofibrous nerve conduits (G-nNCs) were successfully fabricated. The efficacy of NGF gradients was confirmed by a quantitative comparison of dorsal root ganglia (DRG) neurite outgrowth on the G-Ms or uniform NGF-immobilized membranes (U-Ms). Significantly, the neurite turning ratio was 0.48 ± 0.11 for G-M group, but it was close to zero for U-M group. The neurite length of DRGs in the middle of the G-Ms was significantly longer than that of U-M group, even though the average NGF concentration was approximated. Furthermore, 12 weeks after implantation in rats with a 14 mm gap of sciatic nerve injury, G-nNCs achieved satisfying outcomes of nerve regeneration associated with morphological and functional improvements, which was superior to that of the uniform NGF-immobilized nNCs (U-nNCs). Sciatic function index (SFI), compound muscle action potentials (CMAPs), total number of myelinated nerve fibers, thickness of myelin sheath were similar for the G-nNCs and autografts, with the G-nNCs having a higher density of axons than the autografts. Our results demonstrated the significant role of introducing NGF gradients into scaffolds in promoting nerve regeneration.
    No preview · Article · Jun 2013 · Biomaterials
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    ABSTRACT: Platelet-rich plasma (PRP) contains various growth factors and appears to have the potential to promote peripheral nerve regeneration, but evidence is lacking regarding its biological effect on Schwann cells (SCs). The present study was designed to investigate the effect of PRP concentration on SCs in order to determine the plausibility of using this plasma-derived therapy for peripheral nerve injury. PRP was obtained from rats by double-step centrifugation and was characterized by determining platelet numbers and growth factor concentrations. Primary cultures of rat SCs were exposed to various concentrations of PRP (40%, 20%, 10%, 5% and 2.5%). Cell proliferation assays and flow cytometry were performed to study to assess SC proliferation. Quantitative real-time PCR and ELISA analysis were performed to determine the ability of PRP to induce SCs to produce nerve growth factor (NGF) and glial cell line-derived neurotrophic factor (GDNF). Microchemotaxis assay was used to analyse the cell migration capacity. The results obtained indicated that the platelet concentration and growth factors in our PRP preparations were significantly higher than in whole blood. Cell culture experiments showed that 2.5-20% PRP significantly stimulated SC proliferation and migration compared to untreated controls in a dose-dependent manner. In addition, the expression and secretion of NGF and GDNF were significantly increased. However, the above effects of SCs were suppressed by high PRP concentrations (40%). In conclusion, the appropriate concentration of PRP had the potency to stimulate cell proliferation, induced the synthesis of neurotrophic factors and significantly increased migration of SCs dose-dependently. Copyright © 2013 John Wiley & Sons, Ltd.
    No preview · Article · May 2013 · Journal of Tissue Engineering and Regenerative Medicine
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    ABSTRACT: Nano-fibrous scaffolds modified with biological peptides, which can mimic the physical and chemical characteristics of an extracellular matrix (ECM), have been considered good candidate matrices for cell culture in tissue engineering application. In this study, a series of semicrystalline block copolymers, specifically pendent carboxyl-containing poly(ε-caprolactone-co-β-malic acid)-block-poly(l-lactide), were synthesized to fabricate nano-fibrous scaffolds via thermal induced liquid–liquid phase separation process. Random prepolymers P(CL-co-BMD) were first synthesized through ring-opening copolymerization of ε-CL and 3(S)-[(benzyloxycarbony)methyl]-1,4-dioxane-2,5-dione (BMD) in the presence of dodecanol as initiator and stannous octoate(Sn(Oct)2) as catalyst. The terminal hydroxyl of P(CL-co-BMD)-OH was subsequently added to initiate the ring-opening of l-LA catalyzed by Sn(Oct)2. After deprotection, a series of block copolymers, poly(ε-caprolactone-co-β-malic acid)-block-poly(l-lactide)(PCM-b-PLLA), were obtained and fabricated into nanofibrous scaffolds through thermally induced phase separation (TIPS) technique using tetrahydrofuran (THF) as solvent at a gelation temperature of −40 °C. The structure of the copolymers was characterized Nuclear Magnetic Resonance (1H NMR, 13C NMR), Gel Permeation Chromatography (GPC), and Differential Scanning Calorimetry (DSC). The crystallinity of the PCL segment generally decreased when the amount of BMD segment in P(CL-co-BMD) was increased. However, for PCM-b-PLLA, aside from the crystal melting peak of PLLA at 170 °C–180 °C, no indication of PCL section crystallization occurred because the crystallization of the PCL segment was interrupted by PLLA segment. The nanofiber size of the matrices was in the range of 180 nm–650 nm, similar to the architecture of ECM at the nanometer scale. These nanofibrous matrices have design potential to conjugate covalently to bioactive molecules for tissue engineering.
    No preview · Article · Oct 2012 · Polymer
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    ABSTRACT: Acellular porcine corneal stroma (APCS) has been proven to maintain the matrix microenvironment and is therefore an ideal biomaterial for the repair and reconstruction of corneal stroma. This study aims to develop a method to prepare cosmetic corneal lens implants for leukoma using genipin-crosslinked APCS (Gc-APCS). The Gc-APCS was prepared from APCS immersed in 1.0% genipin aqueous solution (pH 5.5) for 4 h at 37 °C, followed by lyophilization at -10 °C. The color of the Gc-APCS gradually deepened to dark-blue. The degree of crosslinking was 45.7 ± 4.6%, measured by the decrease of basic and hydroxy amino acids. The porous structure and ultrastructure of collagenous lamellae were maintained, and the porosity and BET SSA were 72.7 ± 4.6% and 23.01 ± 3.45 m(2)/g, respectively. The Gc-APCS rehydrated to the physiological water content within 5 min and was highly resistant to collagenase digestion. There were no significant differences in the areal modulus and curvature variation between Gc-APCS and nature porcine cornea. The dark-blue pigments were stable to pH, light and implantation in vivo. Gc-APCS extracts had no inhibitory effects on the proliferation of keratocytes. Corneal neovascularization, graft degradation and corneal rejection were not observed within 6 months.
    No preview · Article · Jul 2012 · Biomaterials
  • Jixiang Zhu · Yi Xiong · Chenguang Zeng · Na Qiang · Daping Quan · Jun Wan
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    ABSTRACT: Four kinds of chitosan conduits with longitudinal multi-channels and controlled internal microstructures were prepared using a special mold and a freeze-drying method. One of the conduits was fabricated from a chitosan solution (ab NC), while the other three groups were made from a pre-gelled chitosan solution using genipin as a chemical cross-linker (ab gNC), dibasic sodium phosphate as a physical cross-linker (ab pNC) or a combined ionic and covalent co-cross-linker (ab gpNC), respectively. The porosity of the chitosan conduits ranged from 88 to 90%. The gpNC showed highly interconnected and uniformly distributed pores compared to NC, the gNC and pNC. In contrast, the gNC and gpNC showed about 10% of the volume swelling ratio in 37°C PBS solution, although the gpNC scaffold's water uptake was the highest, at more than 17 times its original mass. Compressive tests showed that gpNC had significant elasticity and maintained its physical integrity even after compressing them down to 20% of their original height. The elastic modulus of gpNC reached 80 kPa, which was more than twice that of the other groups. Adhesion and proliferation of PC12 cells on chitosan gpNC scaffolds showed excellent properties by MTT and SEM observation, which indicated the potential of gpNC scaffolds for nerve tissue engineering applications.
    No preview · Article · Apr 2012 · International journal of biological macromolecules
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    ABSTRACT: A novel anti-proliferative macromolecular conjugate, CS-g-MMCs, was synthesized in order to decrease the cytotoxicity of Mitomycin C (MMC) which was a traditional anti-proliferative agent of fibroblast in trabeculectomy. The structure of CS-g-MMCs was characterized by (1)H NMR, FT-IR spectroscopy and GPC analysis. The grafting degree (dg) of MMC onto chitosan (CS) was determined to be in the range of 2.8-11.3%, which could be controlled by variation of the molar ratios of MMC to oxidized chitosan (CS-CHO). In the drug release profiles of CS-g-MMCs in vitro, an initial burst followed by slow leakage was observed, and addition of acid or lysozyme obviously accelerated the MMC release. The MTS assay indicated that CS-CHO of 8 mg/ml has no cytotoxicity against human Tenon's capsule fibroblasts (HTCFs). The inhibition of HTCFs proliferation by CS-g-MMCs increased along with increasing the dg of conjugate. The CS-g-MMCs also caused the apoptosis of HTCFs and interfered in the active DNA synthesis in HTCFs. Furthermore, the expression of a-SMA at gene and protein levels were obviously lower when HTCFs were treated with CS-g-MMCs, as compared to MMC or blend of MMC/CS-CHO (p<0.05). Our results primarily demonstrated that the CS-g-MMCs conjugates have low cytotoxicity and have the effect to inhibit fibroblast proliferation.
    No preview · Article · Mar 2012 · European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences
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    ABSTRACT: Bone morphogenetic protein 2 (BMP-2) is the most powerful osteogenic factor; its effectiveness in enhancing osteoblastic activation has been confirmed both in vitro and in vivo. We developed a novel peptide (designated P24) derived from the 'knuckle' epitope of BMP-2 and found it also had osteogenic bioactivity to some extent. The main objective of this study was to develop a controlled release system based on poly(trimethylene carbonate)-F127-poly(trimethylene carbonate) (PTMC(11)-F127-PTMC(11)) hydrogels for the P24 peptide, to promote bone formation. By varying the copolymer concentrations, we demonstrated that P24/PTMC(11)-F127-PTMC(11) hydrogels were an efficient system for the sustained release of P24 over 21-35 days. The P24-loaded hydrogels elevated alkaline phosphatase activity and promoted the expression of osteocalcin mRNA in bone marrow stromal cells (BMSCs) in vitro. Radiographic and histological examination showed that P24-loaded hydrogels could induce more effective ectopic bone formation in vivo than P24-free hydrogels. These results indicate that the PTMC(11)-F127-PTMC(11) hydrogel is a suitable carrier for the controlled release of P24, and is a promising injectable biomaterial for the induction of bone regeneration.
    No preview · Article · Jan 2012 · Biomedical Materials

  • No preview · Article · Nov 2011 · Journal of Controlled Release

  • No preview · Article · Nov 2011 · Journal of Controlled Release
  • Mingfa Yan · Tao Wang · Yongkai Huang · Na Qiang · Daping Quan
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    ABSTRACT: In order to study the structure and the catalytic activity of aliphatic tertiary amines, the ring-opening polymerizations of trimethylene carbonate (TMC) and L-lactide (L-LA) were catalyzed by aliphatic tertiary amines, including triethylamine (TEA), N, N, N', N'-tetramethylethylenediamine (TMEDA), 1, 1, 4, 7, 7-pentamethyldiethylenetriamine (PMDTA) and 4-(dimethylamino) pyridine (DMAP), using benzyl alcohol as initiator in THF at 55 degrees C. Studies revealed the catalytic activity of these tertiary amines was increased according to the order: TEA < TMEDA approximate to PMDTA < DMAP. The relationships of polymer molecular weight with the conversion of monomer were linear, which were consistent with a living polymerization character. Finally, the plausible polymerization pathway was through an alcohol-activating mechanism. Aliphatic tertiary amines which were abundant in source and cheap in price were suitable for catalyzing the ring-opening bulk polymerization of lactone in low temperature because of their low boiling point, being liquid under ordinary conditions and being easy to get rid of.
    No preview · Article · Nov 2011 · Acta Polymerica Sinica
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    ABSTRACT: Mitomycin C is an anti-proliferative agent which is usually adopted to prevent fibroblast proliferation in trabeculectomy. However, the shorter half-life of Mitomycin C limits its use. In this paper, a novel anti-proliferative conjugate was synthesized by Schiff base reaction. The cytotoxicity of periodate-oxidized chitosan and drug efficiency were also performed by cell proliferation assay, flow cytometry. The results clearly suggested that the conjugate: periodate-oxidized chitosan-g-mitomycin C could be a suitable polymeric system for controlling the release of mitomycin C.
    No preview · Conference Paper · Jan 2011
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    ABSTRACT: Topographical features, including fiber dimensions and pattern, are important aspects in developing fibrous scaffolds for tissue engineering. In this study aligned poly(l-lactide) (PLLA) fibers with diameters of 307+/-47, 500+/-53, 679+/-72 and 917+/-84 nm and random fibers with diameters of 327+/-40, 545+/-54, 746+/-82 and 1150+/-109 nm were obtained by optimizing the electrospinning parameters. We cultured neonatal mouse cerebellum C17.2 cells on the PLLA fibers. These neural stem cells (NSCs) exhibited significantly different growth and differentiation depending upon fiber dimension and pattern. On aligned fibers cell viability and proliferation was best on 500 nm fibers, and reduced on smaller or larger fibers. However, on random fibers cell viability and proliferation was best with the smallest (350 nm) and largest (1150 nm) diameter fibers. Polarized and elongated cells were orientated along the fiber direction on the aligned fibers, with focal contacts bridging the cell body and aligned fibers. Cells of spindle and polygonal morphologies were randomly distributed on the random fibers, with no focal contacts observed. Moreover, longer neurites were obtained on the aligned fibers than random fibers within the same diameter range. Thus, the surface topographic morphologies of fibrous scaffolds, including fiber pattern, dimensions and mesh size, play roles in regulating the viability, proliferation and neurite outgrowth of NSCs. Nevertheless, our results indicated that aligned 500 nm fiber are most promising for fine tuning the design of a nerve scaffold.
    No preview · Article · Feb 2010 · Acta biomaterialia

Publication Stats

665 Citations
131.00 Total Impact Points


  • 2004-2015
    • Sun Yat-Sen University
      • • Department of Chemical Engineering
      • • State Key Laboratory of Optoelectronic Materials and Technologies
      • • Department of Orthopaedics
      Shengcheng, Guangdong, China
  • 2012
    • Huazhong University of Science and Technology
      • Department of Cancer
      Wu-han-shih, Hubei, China
  • 2002
    • Zhongshan University
      Shengcheng, Guangdong, China