Ke Duan

Southwest Jiaotong University, Hua-yang, Sichuan, China

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Publications (22)73.81 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Drug release from implant surfaces is an effective approach to impart biological activities, (e.g., antimicrobial and osteogenic properties) to bone implants. Coatings of polylactide-based polymer are a candidate for this purpose, but a continuous (fully covering) coating may be non-optimal for implant-bone fixation. This study reports a simple room-temperature method for attaching poly (lactide-co-glycolide) (PLGA) microspheres to titanium (Ti) surfaces. Microspheres were prepared with polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) as the emulsifier. Microspheres were attached to Ti discs by pipetting as a suspension onto the surfaces followed by vacuum drying. After immersion in shaking water bath for 14 d, a substantial proportion of the microspheres remained attached to the discs. In contrast, if the vacuum-drying procedure was omitted, only a small fraction of the microspheres remained attached to the discs after immersion for only 5 min. Microspheres containing triclosan (a broad-spectrum antibiotic) were attached by porous-surfaced Ti discs. In vitro experiments showed that the microsphere-carrying discs were able to kill Staphylococcus aureus and Escherichia Coli, and support the adhesion and growth of primary rat osteoblasts. This simple method may offer a flexible technique for bone implant-based drug release.
    Applied Surface Science 08/2014; 309:112–118. · 2.54 Impact Factor
  • Journal of Inorganic Materials 08/2013; 28(8):804-810. · 0.54 Impact Factor
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    ABSTRACT: In vivo engineering of bone autografts using bioceramic scaffolds with appropriate porous structures is a potential approach to prepare autologous bone grafts for the repair of critical-sized bone defects. This study investigated the evolutionary process of osteogenesis, angiogenesis, and compressive strength of bioceramic scaffolds implanted in two non-osseous sites of dogs: the abdominal cavity and the dorsal muscle. Hydroxyapatite (HA) sphere-accumulated scaffolds (HASA) with controlled porous structures were prepared and placed in the two sites for up to 6 months. Analyses of retrieved scaffolds found that osteogenesis and angiogenesis were faster in scaffolds implanted in dorsal muscles compared with those placed in abdominal cavities. The abdominal cavity, however, can accommodate larger bone grafts with designed shape. Analyses of scaffolds implanted in abdominal cavities (an environment of a low mesenchymal stem cell density) further demonstrated that angiogenesis play critical roles during osteogenesis in the scaffolds, presumably by supplying progenitor cells and/or mesenchymal stem cells as seed cells. This study also examined the relationship between the volume of bone grafts and the physiological environment of in vivo bioreactor. These results provide basic information for the selection of appropriate implanting sites and culture time required to engineer autologous bone grafts for the clinical bone defect repair. Based on these positive results, a pilot study has applied the grafts constructed in canine abdominal cavity to repair segmental bone defect in load-bearing sites (limbs).
    Journal of Biomedical Materials Research Part A 08/2013; · 2.83 Impact Factor
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    ABSTRACT: The aim of this study is to investigate the tribological behaviors and wear mechanisms of ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN), a potential drug to treat osteolysis, under different normal loads and lubrication conditions. A mixture of UHMWPE powder and ALN (1.0wt.%) solution was dried and hot pressed. The static and dynamic friction coefficients of UHMWPE-ALN were slightly higher than those of UHMWPE except under normal load as 10N and in 25v/v % calf serum. The specific wear rates of UHMWPE-ALN and UHMWPE were the lowest in 25v/v % calf serum compared to those in deionized water or physiological saline. In particular, the specific wear rate of UHMWPE-ALN was lower than that of UHMWPE at 50N in 25v/v % calf serum. The main wear mechanisms of UHMWPE and UHMWPE-ALN in deionized water and UHMWPE in physiological saline were abrasive. The main wear mechanism of UHMWPE-ALN in physiological saline was micro-fatigue. In 25v/v % calf serum, the main wear mechanism of UHMWPE and UHMWPE-ALN was abrasive wear accompanied with plastic deformation. The results of Micro-XRD indicated that the molecular deformation of UHMWPE-ALN and UHMWPE under the lower stress were in the amorphous region but in the crystalline region at the higher stress. These results showed that the wear of UHMWPE-ALN would be reduced under calf serum lubricated, which would be potentially applied to treat osteolysis.
    Materials science & engineering. C, Materials for biological applications. 07/2013; 33(5):3001-9.
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    ABSTRACT: Vascularized bone grafts were constructed by implanting hydroxyapatite (HA) scaffolds with complementary macro-pore structures into the dorsal muscle of dogs. The relationship between pore structures and ectopic bone formation properties were investigated. Two types of scaffolds with complementary porous structures were fabricated by spherulite-accumulating and porogen-preparing methods, which were named as spherulite HA-positive and porogen HA-negative, respectively. After 1 month implantation, histological observation showed that all the scaffolds were encapsulated by normal muscle tissue and multiple vascular net with cells, indicating excellent biocompatibility and pore interconnectivity of the scaffolds. In the spherulite HA-positive scaffolds, a number of osteoclasts and osteoblasts coupled with new bone tissues were found after 3 and 6 months implantations, which was better than those in the porogen HA-negative scaffolds. Similarly, the improvement of mechanical properties and the reconstruction of materials in the spherulite HA-positive scaffolds were superior to those in the porogen-HA negative scaffolds. The different ectopic bone formation induced by different macro-pore structures after intramuscular implantation demonstrated the significant effect of macro-pore structures of scaffolds on osteoinduction and vascularisation.
    Acta biomaterialia 05/2013; · 5.68 Impact Factor
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    ABSTRACT: The present work shows drug-carrier interactions, release behaviors and cell responses of hydroxyapatite (HA) containing salvianolic acid B (Sal B), astragalus polysaccharide (APS), and naringin. X-ray diffraction (XRD) showed that the crystallinity and crystal size of HA decreased significantly when Sal B was added (p<0.05). Transmission electron microscope (TEM) confirmed that the nano-acicular crystals of HA containing Sal B were the most fine among all specimens. It was conjectured that Sal B preferentially adsorbed on the positively charged surface of HA crystals to inhibit their growth. In vitro release of HA containing Chinese medicines followed the first-order equation. The drug-carrier affinity between HA and Sal B might have prolonged the release of Sal B. The proliferation and differentiation of osteoblasts were promoted by Chinese medicines containing HA in the time and dosage dependent manner. The osteoblasts displayed a polygonal morphology with cell-cell junctions in all cases. It is suggested that the contained Chinese medicines would promote the activities of the osteoblasts.
    Journal of Wuhan University of Technology-Mater Sci Ed 02/2013; 28(1). · 0.42 Impact Factor
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    ABSTRACT: Carbon nanotubes (CNTs)/hydroxyapatite (HA) nanocomposites with ferromagnetic properties have been fabricated via an in situ process in which a HA-based matrix was used as the catalyst for the growth of CNTs in a chemical vapor deposition system. The results showed that approximately 20 wt% of multi-walled CNTs with a mean diameter of 40–60 nm have been produced in the nanocomposites. The CNTs in the nanocomposites were observed to have an undamaged structure, with ordered graphitic layers and non-defective lattice structure on their walls. The growth of CNTs are shown to be in situ from the nano-HA crystallites. The compress mechanical properties of these CNTs/HA composites prepared by this method were significantly better than that of the composites prepared by physical mixing CNTs with HA particles. Magnetic measurement showed that the nanocomposites exhibit a ferromagnetic behavior with a saturation magnetization of 0.126 emu g−1 at a room temperature. These magnetic nanocomposites could have a potential application in the drug delivery system as well as other biomedical fields.
    Applied Surface Science 12/2012; 262:110–113. · 2.54 Impact Factor
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    ABSTRACT: HA/PVA composites at different weight ratios were prepared by in situ growth of HA crystallites in PVA gels, and some interesting shape memory behaviors were investigated. Those results showed that HA/PVA composites at a weight ratio of 1:20, 1:10, and 1:5 had desirable shape memory effects. The initial shapes of pure PVA and HA/PVA composites were recovered automatically in 40 s and HA particles in PVA-matrix composites played an important role during the shape memory recovery.
    Polymer-Plastics Technology and Engineering 09/2012; 51(13). · 1.48 Impact Factor
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    ABSTRACT: The aim of this study is to investigate in vitro release and cell response to wear particles of ultrahigh molecular weight polyethylene loaded with alendronate sodium (UHMWPE-ALN), a potent bone resorption inhibitor. Wear particles of UHMWPE-ALN with different ALN contents (0.5 wt % or 1.0 wt %) and size ranges (<45 μm or 45-75 μm) were cocultured with macrophages (RAW264.7) and osteoblasts (MC3T3-E1), respectively. The in vitro ALN release was divided into three stages: an initial burst release, subsequent rapid release, and final slow release. The particle size and ALN content of UHMWPE-ALN wear particles affected the in vitro release mainly during initial burst and rapid release. Compared with the control cells, UHMWPE-ALN wear particles stimulated a significant elevation of tumor necrosis factor-alpha (TNF-α) release from macrophages but had no obvious effect on interleukin-6 release. However, this stimulation of TNF-α release could be reduced by ALN released from UHMWPE-ALN wear particles. The wear particle size had stronger effect of on the macrophages compared with the ALN concentration. After coculture with UHMWPE-ALN wear particles, osteoblast proliferation and alkaline phosphatase activities increased moderately with the increase in particle sizes and ALN concentrations. These results suggest that incorporation of ALN in UHMWPE-ALN may be an effective approach to prevent or reduce particles-induced osteolysis. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2012.
    Journal of Biomedical Materials Research Part A 07/2012; · 2.83 Impact Factor
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    ABSTRACT: In the present work, porous titanium with a porosity of 70% was prepared using the space-holder sintering process. Then the porous titanium was treated by micro-arc oxidation (MAO) in the aqueous electrolyte. The results showed that TiO layers were formed on titanium at applied voltages (90–100 V) and in short time (1–3 min). The morphology of the TiO layer was investigated and the apatite-inducing ability was evaluated in a modified simulated body fluid (2 SBF). It revealed that the increases of MAO time and applied voltage contributed to the formation of bioactive apatite on the surface of film on the porous titanium scaffold. The TiO layer possesses high apatite-forming ability. Therefore, the TiO layer prepared by MAO can be used to modify the surface of the porous titanium implants.
    Applied Surface Science 07/2012; 258(19):7584–7588. · 2.54 Impact Factor
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    ABSTRACT: In this study, a simple and effective method for producing highly interconnected porous hydroxyapatite (HA) scaffolds was developed by combining gel-casting, particle-leaching and extrusion techniques. Chitin (CT) sol was used to disperse HA particles and wax spheres were introduced as porogens for their excellent deformability. In extrusion process, the accumulated wax spheres in point-to-point contact can transform into surface-to-surface contact by means of the extrusion pressure. Thus, the obtained porous HA scaffolds exhibited an interconnected channel network after leaching out of the porogens. The results showed that the scaffolds prepared by different size of wax spheres exhibited nearly the same volumetric porosity of about 86%, while the compressive strengths decreased as the pore size increased. Therefore, the method developed can be used to effectively tailor the pore size of HA scaffolds while maintaining a high porosity. The highly porous HA scaffolds with excellent interconnectivity are expected to be a promising bone substitute in clinical practice.
    Materials Science and Engineering C 04/2011; 31(3):697-701. · 2.74 Impact Factor
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    ABSTRACT: Metal oxide microspheres have potential applications in many fields. However, so far, the construction and controlling of nanostructures which play a crucial role in tailoring the properties of microspheres and hollow microspheres are still difficult. In this work, we were the first to successfully tune the nanostructures of spheres and hollow spheres of ZnO during a solvothermal reaction system by using imidazolium tetrafluoroborate ionic liquids. The results indicate that not only can ionic liquids be used as soft templates to provide a really facile approach for the elaboration of hierarchical nanostructures but also this solvothermal reaction system associated with ionic liquids may be regarded as a hybrid solvothermal and ionothermal system, which possesses a “two in one” advantage and hence can provide a powerful tool for the synthesis of novel materials with interesting morphologies and properties in the future.
    Journal of Materials Chemistry 11/2010; 20(43):9798-9804. · 6.63 Impact Factor
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    ABSTRACT: Prevention of implant-associated infections has been one of the main challenges in orthopaedic surgery. This challenge is further complicated by the concern over the development of antibiotic resistance as a result of using traditional antibiotics for infection prophylaxis. The objective of this study was to develop a technique that enables the loading and local delivery of a unique group of cationic antimicrobial peptides (AMP) through implant surfaces. A thin layer of micro-porous calcium phosphate (CaP) coating was processed by electrolytic deposition onto the surface of titanium as the drug carrier. The broad spectrum AMP Tet213 (KRWWKWWRRC) was selected and loaded onto the CaP coating. SEM, XRD and FTIR analyses confirmed the CaP coating to be micro-porous octacalcium phosphate. By using a luminescence spectrometer technique, it was demonstrated that a 7 μm thick porous CaP coating could load up to 9 μg of AMP/cm² using a simple soaking technique. The drug-loaded CaP coating (CaP-Tet213) was not cytotoxic for MG-63 osteoblast-like cells. The CaP-Tet213 implants had antimicrobial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria with 10⁶-fold reductions of both bacterial strains within 30 min as assessed by measuring colony-forming units (CFU). Repeated CFU assays on the same CaP-Tet213 specimen demonstrated retention of antimicrobial activity by the CaP-Tet213 surfaces through four test cycles. The susceptibility of bacteria to the CaP-Tet213 surfaces was also evaluated by assessing the inhibition of luminescence of P. aeruginosa containing a luxCDABE cassette at 4 h and 24 h with ∼92% and ∼77% inhibition of luminescence, respectively. It was demonstrated that CaP-Tet213 was a more efficient antimicrobial coating than CaP-MX226, CaP-hLF1-11 or CaP-tobramycin following incubation of CaP implants with equimolar concentrations of Tet213, the commercially developed antimicrobial peptide MX-226, hLF1-11 or tobramycin. A device coated with CaP-Tet213 could be a potential solution for the prevention of the peri-implant infection in orthopaedics.
    Biomaterials 10/2010; 31(36):9519-26. · 8.31 Impact Factor
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    ABSTRACT: This study aims to improve the tensile strength and elastic modulus of nano-apatite/poly(ε-caprolactone) composites by silane-modification of the nano-apatite fillers. Three silane coupling agents were used to modify the surfaces of nano-apatite particles and composites of silanized apatite and PCL were prepared by a technique incorporating solvent dispersion, melting-blend and hot-pressing. The results showed that the silane coupling agents successfully modified the surfaces of nano-apatite fillers, and the crystallization temperatures of the silanized apatite/PCL composites were the higher than that of the non-silanized control material, although the melting temperature of the composites remained almost unaffected by silanization. The ultimate tensile strength and elastic modulus of the silanized composites reached 22.60 MPa and 1.76 GPa, as a result of the improved interfacial bonding and uniform dispersion of nano-apatite fillers. This study shows that the processing technique and silanization of nano-apatite particles can effectively improve the tensile strength and elastic modulus of nano-apatite/PCL composites.
    Journal of Materials Science Materials in Medicine 10/2010; 21(12):3059-64. · 2.14 Impact Factor
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    ABSTRACT: Polycaprolactone (PCL)-coated porous hydroxyapatite (HA) composite scaffolds were prepared by combining polymer impregnating method with dip-coating method. Three different PCL solution concentrations were used in dip-coating process to improve the mechanical properties of porous HA scaffolds. The results indicated that as the concentration of PCL solution increases the compressive strength significantly increased from 0.09MPa to 0.51MPa while the porosity decreased from 90% to 75% for the composite scaffolds. An interlaced structure was found inside the pore wall for all composite scaffolds due to the penetration of PCL. The porous HA/PCL composite scaffolds dip-coated with 10% PCL exhibited optimal combination of mechanical properties and pore interconnectivity, and may be a potential bone candidate for the tissue engineering applications.
    Applied Surface Science 05/2010; 256(14):4586-4590. · 2.54 Impact Factor
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    ABSTRACT: Interconnected porous hydroxyapatite (HA) scaffolds are widely used for bone repair and replacement, owing to their ability to support the adhesion, transfer, proliferation and differentiation of cells. In the present study, the polymer impregnation approach was adopted to produce porous HA scaffolds with three-dimensional (3D) porous structures. These scaffolds have an advantage of highly interconnected porosity (approximately 85%) but a drawback of poor mechanical strength. Therefore, the as-prepared HA scaffolds were lined with composite polymer coatings in order to improve the mechanical properties and retain its good bioactivity and biocompatibility at the same time. The composite coatings were based on poly(D,L-lactide) (PDLLA) polymer solutions, and contained single component or combination of HA, calcium sulfate (CS) and chondroitin sulfate (ChS) powders. The effects of composite coatings on scaffold porosity, microstructure, mechanical property, in vitro mineralizing behavior, and cell attachment of the resultant scaffolds were investigated. The results showed that the scaffolds with composite coatings resulted in significant improvement in both mechanical and biological properties while retaining the 3D interconnected porous structure. The in vitro mineralizing behaviors were mainly related to the compositions of CS and ChS powders in the composite coatings. Excellent cell attachments were observed on the pure HA scaffold as well as the three types of composite scaffolds. These composite scaffolds with improved mechanical properties and bioactivities are promising bone substitutes in tissue engineering fields.
    Colloids and surfaces B: Biointerfaces 08/2009; 74(1):159-66. · 4.28 Impact Factor
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    ABSTRACT: This study reports a new method to prepare biomimetic calcium phosphate coatings on titanium, stainless steel, CoCrMo, and tantalum. The method does not require surface etching, high supersaturation, or tight control of solution conditions. Metallic samples were dipped into a supersaturated calcium phosphate solution, withdrawn, and left to dry at room temperature. Calcium phosphate crystallites formed on and completely covered the surfaces by repeating the dip-and-dry treatment. The crystallite-covered surfaces readily grew to calcium phosphate coatings when immersed in the supersaturated solution. The mechanism of the treatment was suggested to be an evaporation-induced surface crystallization process.
    Materials Science and Engineering C 05/2009; 29(4):1334-1337. · 2.74 Impact Factor
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    ABSTRACT: Poly(lactic-co-glycolic acid) (PLGA) is a promising material for the regeneration of bone tissue, but its surface properties are not optimal for the application. Coating the surface of PLGA with a continuous layer of calcium phosphate is an effective approach to address the limitation. Current coating techniques for PLGA require immersion in supersaturated calcium phosphate solutions for days to weeks. In this study, we report a simple technique to accelerate the coating process to only 2 h immersion in supersaturated solutions. PLGA pellets were first treated with NaOH to increase their hydrophilicity. The NaOH-treated PLGA pellets were repeatedly dipped in a supersaturated calcium phosphate solution and dried in air. After 10 times of the dip-and-dry treatment, a layer of calcium phosphate crystallites uniformly covered the surfaces of the pellets. After the crystallite-covered pellets were immersed in the supersaturated solution for 2 h, about 5-μm thick continuous calcium phosphate coatings formed on the surfaces. The dip-and-dry technique was also applied on a variety of metals and porous structures. An evaporation-induced surface crystallization process was suggested as the mechanism for the dip-and-dry treatment.
    Applied Surface Science 12/2008; 255(5):2442-2448. · 2.54 Impact Factor
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    ABSTRACT: Porous tantalum has been shown to be effective in achieving bone ingrowth. However, in some circumstances, bone quality or quantity may be insufficient to allow adequate bone ingrowth. We hypothesized that local delivery of alendronate from porous tantalum would enhance the ability of the tantalum to achieve bone ingrowth when there is a gap between the implant and bone. We evaluated the effect of alendronate-coated porous tantalum on new bone formation in an animal model incorporating a gap between the implant and bone. A cylindrical porous tantalum implant was implanted in the distal part of each femur in eighteen rabbits (a total of thirty-six implants) and left in situ for four weeks. Three types of porous tantalum implants were inserted: those with no coating (the control group), those with microporous calcium phosphate coating, and those coated with microporous calcium phosphate and alendronate. Subcutaneous fluorescent labeling was used to track new bone formation. Bone formation was analyzed with backscattered electron microscopy and fluorescent microscopy of undecalcified samples. The relative increases in the mean volume of gap filling, bone ingrowth, and total bone formation in the group treated with the porous tantalum implants coated with calcium phosphate and alendronate were 143% (p < 0.001), 259% (p < 0.001), and 193% (p < 0.001), respectively, compared with the values in the control group treated with the uncoated porous tantalum implants. The percentage of the length of the implant that was in contact with new bone in the group treated with the calcium phosphate and alendronate coating was increased by an average of 804% compared with the percentage in the group treated with the uncoated implants. The study demonstrated significantly enhanced filling of the bone-implant gap and bone ingrowth in association with the porous tantalum implants coated with calcium phosphate and alendronate.
    The Journal of Bone and Joint Surgery 05/2008; 90(5):1090-100. · 3.23 Impact Factor
  • Ke Duan, Rizhi Wang
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    ABSTRACT: Bone implants are widely used in orthopedics and dentistry to treat hard tissue disorders. The surfaces of implants are critical in determining their performances. Many techniques are used or are being developed to modify implant surfaces. Among the techniques, low temperature wet chemical methods present unique advantages. This review summaries current applications and research of low temperature wet chemical methods in modifying the surfaces of permanent and resorbable implants and the use of modified surfaces for local delivery of pharmaceuticals. Potential future developments and opportunities are also discussed in this review.
    Journal of Materials Chemistry 01/2006; 16(24). · 6.63 Impact Factor

Publication Stats

207 Citations
73.81 Total Impact Points


  • 2009–2014
    • Southwest Jiaotong University
      • • School of Materials Science and Engineering
      • • Key Laboratory of Advanced Technology of Materials (Chinese Education Ministry)
      Hua-yang, Sichuan, China
  • 2005–2010
    • University of British Columbia - Vancouver
      • Department of Materials Engineering
      Vancouver, British Columbia, Canada