Qing Cai

Peking University, Peping, Beijing, China

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Publications (94)211.01 Total impact

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    ABSTRACT: Hybridized carbon nanofibers containing calcium phosphate nanoparticles (CNF/CaP) were investigated as osteocompatible nanofillers for epoxy resin. The CNF/CaP was produced by electrospinning mixture solution of polyacrylonitrile and CaP precursor sol–gel, followed by preoxidation and carbonization. The continuous and long CNF/CaP was ultrasonically chopped, mixed into epoxy resin and thermo-cured. Compared to pure CNFs with similar ultrasonication treatment, the shortened CNF/CaP reinforced composites demonstrated significant enhancement in flexural properties of epoxy composites, benefiting from the improved interfacial adhesion between CNF/CaP and resin matrix. The resulting composites also displayed good biocompatibility and sustained calcium ion release, which categorized them as promising materials for bone repairing.
    No preview · Article · Apr 2016
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    ABSTRACT: The major objective of this study was to explore the effects of silicon dioxide (SiO2) nanofibers on the performance of 2, 2-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA)/tri-(ethyleneglycol) dimethacrylate (TEGDMA) dental composites. At first, the mechanical properties of Bis-GMA/TEGDMA (50/50, w/w) resins containing different contents of SiO2 nanofibers were evaluated to identify the appropriate composition to achieve the significant reinforcing effect. Secondly, optimized contents (5 or 10 wt.%) of SiO2 nanofibers were mixed into resins together with SiO2 microparticles, which was 60 wt.% of the resin. Controls for comparison were Bis-GMA/TEGDMA resins containing only SiO2 microparticles (60 wt.%) or with additional SiO2 nanoparticles (5 or 10 wt.%). Properties including abrasion, polymerization shrinkage and mechanical properties were evaluated to determine the contribution of SiO2 nanofibers. In comparison with SiO2 nanoparticles, SiO2 nanofibers improved the overall performance of Bis-GMA/TEGDMA composite resins, especially in improving abrasion resistance and decreasing polymerization shrinkage. The explanations were that one-dimensional SiO2 nanofibers were able to shield particular fillers from being abraded off, and able to form a kind of overlapped fibrous network to resist polymerization shrinkage. With these approaches, SiO2 nanofiber-containing Bis-GMA composite resins were envisioned a promising choice to achieve long-term durable restorations in clinical therapies.
    No preview · Article · Feb 2016
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    ABSTRACT: A new type of MnO/carbon composite particles with multi-modal pore structure was designed and prepared as anode materials of lithium-ion batteries through a modified template method. The porous MnO/carbon composite anode materials exhibited the superior electrochemical performance, including excellent stability under different current density, high reversible capacity (as high as 1210.9 mA h g-1 after 700 cycles at 1.0 A g-1 ), good rate capability and high initial coulomb efficiency of over 80%, which had benefited from the reasonable material composition, special multi-modal pore structure, desirable micro-morphology and good structure integrity. The complex multiphase structure consisting of MnO crystal grains, abundant nanopores and uniform carbon layers can effectively improve cyclic stability and rate capability of the anode materials, thus will display an important application value in high-performance energy supply devices.
    No preview · Article · Jan 2016 · Journal of Materials Chemistry A
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    ABSTRACT: To obtain a kind of light-curable fiber-reinforced composite for dental restoration, an excellent interfacial adhesion between the fiber and the acrylate resin matrix is quite essential. Herein, surface modification on glass fibers were carried out by coating them with poly(methyl methacrylate) (PMMA), polydopamine (PDA), or both. The PMMA or PDA coating was performed by soaking fibers in PMMA/acetone solution or dopamine aqueous solution. PDA/PMMA co-coated glass fibers were obtained by further soaking PDA-coated fibers in PMMA/acetone solution. These modified fibers were impregnated with bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (5:5, w/w) dental resin at a volume fraction of 75%, using unmodified fibers as reference. Light-cured specimens were submitted to evaluations including flexural properties, morphological observation, dynamic mechanical thermal analysis (DMTA) and pull-out test. In comparison with unmodified glass fibers, all the modified glass fibers showed enhancements in flexural strength and modulus of Bis-GMA/TEGDMA resin composites. Results of DMTA and pull-out tests confirmed that surface modification had significantly improved the interfacial adhesion between the glass fiber and the resin matrix. Particularly, the PDA/PMMA co-coated glass fibers displayed the most efficient reinforcement and the strongest interfacial adhesion due to the synergetic effects of PDA and PMMA. It indicated that co-coating method was a promising approach in modifying the interfacial compatibility between inorganic glass fiber and organic resin matrix.
    No preview · Article · Jan 2016 · Materials Science and Engineering C
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    ABSTRACT: Composite carbon nanofibers (CNFs) containing bioglass (BG) nanoparticles displayed different morphology and microstructures depending on the sintering temperature (800, 1000 and 1200 °C) when they were produced from an electrospun polyacrylonitrile–BG precursor blend nanofibers. Biomineralization using simulated body fluid (SBF) and biological evaluation using an osteoblast culture were performed to investigate their relationship with sintering temperature. Characterization revealed that the BG nanoparticles on CNF/BG sintered at 1000 °C (CNF/BG-1000) possessed small particle size and uniform size distribution, and the crystallinity of the BG nanoparticles increased as the sintering temperature was increased from 800 to 1200 °C. The dissolution rate of the BG nanoparticles was thus different between the cases, which enhanced the biomineralization and cell proliferation/differentiation to varying degrees. Benefiting from the homogeneous distribution and large specific surface area of the BG nanoparticles on the CNFs, the results demonstrated that CNF/BG-1000 had the strongest ability in promoting apatite deposition, proliferation and osteogenic differentiation of MC3T3-E1 pre-osteoblasts in comparison with CNF/BG sintered at 800 or 1200 °C. The results demonstrate a flexible tool to regulate the physiochemical and biological properties of CNF/BG composites by controlling the sintering temperature, which could find promising applications in skeleton repairing.
    No preview · Article · Dec 2015 · RSC Advances
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    ABSTRACT: This paper evaluated the push-out bond strengths of glass fiber posts with poly-dopamine (poly-dopa) functionalized after etching with H2O2. Forty extracted human, single-rooted teeth were endodontically treated and a 9-mm post space was prepared in each tooth with post drills provided by the manufacturer. Specimens were randomly assigned into four groups (n=10 per group), depending on post surface treatment used: group C (control); group D (poly-dopa); group H (H2O2); and group HD (H2O2+poly-dopa). The push-out test was performed using a universal testing machine. Results: Bond strengths (MPa) were as follows: 4.678±0.911 (group C); 7.909±1.987 (group D); 6.519±0.893 (group H); and 9.043±1.596 (group HD). The bond strength of the resin cement to posts functionalized with poly-dopa was not affected by H2O2 pre-treatment, while conditioning using H2O2+poly-dopa resulted in higher bond strengths than H2O2 treatment only. Compared to H2O2 treatment, the bond strength of poly-dopa conditioning was superior. © 2015, Japanese Society for Dental Materials and Devices. All rights reserved.
    Preview · Article · Dec 2015 · Dental Materials Journal
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    ABSTRACT: In tissue engineering, most polymeric scaffolds should degrade along with the formation of the new tissues. Therefore, it is necessary to look into the in vivo degradation of scaffolds. In this study, a fluorescent perylenediimide-cored (PDI-cored) dendritic star macromolecule bearing multiple amines (d-p48) was incorporated into biodegradable polyester nanofibrous scaffolds by eletrospinning as an indicator. The polyester/d-p48 blend nanofibers could emit strong red fluorescence when they were irradiated under exciting light. Initially, using slowly degradable polyester, poly(L-lactide) (PLLA)/d-p48 nanofibers were soaked in phosphate buffered saline for various lengths of time to determine the possible diffusing release of d-p48 macromolecule from nanofibers. The PLLA/d-p48 nanofibers were then implanted subcutaneously into mice and left for up to 2 weeks. In both cases, no undesirable release of the incorporated d-p48 macromolecule was detected, and the nanofibers were clearly visualized in vivo by fluorescence microscopy. Using a fast degradable polyester, poly(lactide-co-glycolide) (PLGA)/d-p48 nanofibers were electrospun and implanted subcutaneously to determine the possibility of monitoring in vivo degradation by fluorescence during 12 weeks. The results showed that the location and the contour of PLGA/d-p48 nanofibrous scaffolds could be clearly visualized using an animal fluorescent imaging system. The fluorescent intensities decreased gradually with the degradation of the scaffolds. No side effects on liver and kidney were found during the detection. This study indicates that the fluorescent PDI-cored dendritic star macromolecule can be used as a stable bioimaging indicator for biodegradable aliphatic polyesters in vivo.
    Full-text · Article · Nov 2015 · Biomedical Materials
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    ABSTRACT: The poor interfacial adhesion between organic and inorganic components remains the primary obstacle in obtaining composite scaffolds of high performance for bone tissue engineering. Mussel-inspired dopamine surface modification on inorganic components is a potential solution for this problem. Herein, hydroxyapatite (HA) nano-rods were freshly made by a co-precipitation method and subjected to polydopamine (PDA) coating. Then the modified HA nano-rods were mixed into biodegradable poly(l-lactide) (PLLA) to get PLLA/HA nanocomposites. The PDA modification was found to be mild and easy to handle, and was effective in improving the dispersibility of HA nano-rods in chloroform and especially in PLLA/chloroform solution. The resulting PLLA/HA composite films and porous scaffolds demonstrated significant enhancements in their mechanical properties at relatively high contents (30-60 wt%) of modified HA nano-rods in comparison with those composites containing unmodified HA nano-rods. This was thought to be mainly attributed to both the even distribution of modified HA nano-rods throughout the PLLA matrix and the strong interfacial adhesion between HA and PLLA components. The PLLA/HA composites displayed good biocompatibility with bone mesenchymal stem cells (BMSCs) and could enhance the osteogenic differentiation of BMSCs, indicating the PDA modification has no adverse effect on biological properties. These results confirmed the idea of using mussel-inspired dopamine surface modification as a feasible and efficient approach in developing organic-inorganic composite materials for bone regeneration studies.
    No preview · Article · Oct 2015 · RSC Advances
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    ABSTRACT: Bioactive glass (BG)-containing carbon nanofibers (CNFs) are promising orthopaedic biomaterials. Herein, CNF composites were produced from electrospinning of polyacrylonitrile (PAN)/BG sol-gel precursor solution, followed by carbonization. Choosing 58S-type BG (mol%: 58.0% SiO2-26.3% CaO-15.7% P2O5) as the model, micro-structural evolution of CNF/BG composites was systematically evaluated in relating to aging times of BG precursor solution. With aging time prolonging, BG precursors underwent morphological changes from small sol clusters with loosely and randomly branched structure to highly crosslinked Si-network structure, showing continuous increase in solution viscosity. BG precursor solution with low viscosity could mix well with PAN solution, resulting in CNF composite with homogeneously distributed BG component. Whereas, BG precursor gel with densely crosslinked Si-network structure led to uneven distribution of BG component along final CNFs due to its significant phase separation from PAN component. Meanwhile, BG nanoparticles in CNFs demonstrated micro-structural evolution that they transited from weak to strong crystal state along with longer aging time. Biomineralization in simulated body fluid and in vitro osteoblasts proliferation were then applied to determine the bioactivity of CNF/BG composites. CNF/BG composites prepared from shorter aging time could induce both faster apatite deposition and cell proliferation rate. It was suggested weakly crystallized BG nanoparticles along CNFs dissolved fast and was able to provide numerous nucleation sites for apatite deposition, which also favored the proliferation of osteoblasts cells. Aging time could thus be a useful tool to regulate the biological features of CNF/BG composites.
    No preview · Article · Oct 2015 · Colloids and surfaces B: Biointerfaces
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    Full-text · Dataset · Oct 2015
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    Full-text · Dataset · Oct 2015
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    ABSTRACT: From physiological point of view, organic-inorganic composite nanofibers are envisioned promising substrates for bone tissue engineering. Biomineralization on polymeric nanofibers using simulated body fluid (SBF) is a common technique to obtain the composite nanofibers. Many factors, however, will affect the nucleation and crystal growth of deposited apatite, such as the additives like amino acids in SBF. In this study, electrospun composite nanofibers consisting of poly(L-lactide) (PLLA, 50wt%) and gelatin (50wt%) were soaked in 2.5 times SBF (2.5SBF) for different time periods (1, 2, 3, 5 and 7 days) to perform the biomineralization. Three amino acids (glycine, aspartic acid, or arginine) of different charge characteristics were introduced into the SBF, and their effects on nucleation and transformation of calcium phosphate depositions were systematically investigated. The results revealed that amino acids could take part in the early stage formation of pre-nucleation clusters, leading to different assemblies dependent closely on the feature of amino acid. In comparison with normal 2.5SBF, the presence of amino acid was able to enhance the preferred orientation of hydroxyapatite (HA) crystal along c axis and the transformation from amorphous calcium phosphate to hierarchical HA. The incorporation of glycine had promoted the formation of the well-evolved needle-like HA crystals in comparison with aspartic acid or arginine. It was suggested that the addition of amino acids into SBF might be a useful tool to regulate the biomineralizaiton for preparing organic-inorganic composite nanofibers.
    No preview · Article · Sep 2015 · Applied Surface Science
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    ABSTRACT: In this study, thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) was grafted onto gelatin via atom transfer radical polymerization (ATRP). The chemical structure of PNIPAAm-grafted gelatin (Gel-PNIPAAm) was confirmed by XPS, ATR-IR and 1H NMR characterizations. Gel-PNIPAAm aqueous solution exhibited sol-to-gel transformation at physiological temperature, and was studied as injectable hydrogel for bone defect regeneration in a cranial model. The hydrogel was biocompatible and demonstrated the ability to enhance bone regeneration in comparison with the untreated group (control). With the incor-poration of rat bone mesenchymal stem cells (BMSCs) into the hydrogel, the bone regeneration rate was further significantly enhanced. As indicated by micro-CT, histological (H&E and Masson) and immunohistochemical (osteocalcin and osteopontin) staining, at 12 weeks post-implantation, newly formed woven bone tissue was clearly detected in the hydrogel/BMSCs treated group, showing indistinguishable boundary with surrounding host bone tissues. The results suggested that the thermo-sensitive Gel-PNIPAAm hydrogel was an excellent injectable delivery vehicle of BMSCs for in vivo bone defect regeneration.
    No preview · Article · Aug 2015 · ACS Applied Materials & Interfaces
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    ABSTRACT: Core-shell polymer spheres of submicron diameter are a promising vehicle for sequential delivery of angiogenic and osteogenic growth factors to bone defect sites, to simulate the orchestrated temporal sequence of angiogenesis and osteogenesis. To achieve a homogeneous distribution pattern in the scaffold matrix and avoid fast biological clearance in vivo, attention should be paid to the particle size of the spheres, using a modified coaxial electrospraying technique, we prepared core-shell spheres about 1 μm in diameter using the polymers poly-(d,l-lactide) in the shell and poly(l-lactide-co-glycolic acid) in the core, and loaded them with VEGF and BMP-2, growth factors that stimulate angiogenesis and osteogenesis, respectively. PLGA/PDLLA controlled sequential delivery profiles, including an initial burst release of VEGF and a sustained release behavior of BMP-2 from the VEGF//BMP-2 spheres, were obtained. The VEGF and BMP-2 released from the spheres maintained their bioactivity; VEGF could enhance the proliferation of endothelial cells and BMP-2 could promote the osteogenic differentiation of bone marrow mesenchymal stem cells. Micro-computed tomography analysis showed that, among all the experimental groups, implantation of VEGF//BMP-2 spheres into rat cranial critical-sized bone defects enhanced new bone formation to the greatest extent, resulting in the largest amount of new bone volume and the largest isolated bone islands. Histological examination showed that VEGF//BMP-2 spheres also significantly increased in-growth of blood vessels with positive CD31 staining. All these findings suggest that the submicron-scale core-shell VEGF//BMP-2 spheres developed in this study are capable of yielding sequentially coupled angiogenesis and osteogenesis, implying their extensive application in bone tissue regeneration.
    No preview · Article · Aug 2015 · The Chemical Engineering Journal
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    ABSTRACT: A novel fiber-in-tube hierarchical nanostructure of SnO2@porous carbon in carbon tubes (SnO2@PC/CTs) is creatively designed and synthesized though a carbon coating on scalable electrospun hybrid nanofibers template and a post-etching technique. This 1D nanoarchitecture consists of double carbon-buffering matrixes, i.e., the external carbon tubular shell and the internal porous carbon skeleton, which can work synergistically to address the various issues of SnO2 nanoanode operation, such as pulverization, particle aggregation, and vulnerable electrical contacts between the SnO2 nanoparticles and the carbon conductors. Thus, the as-obtained SnO2@PC/CTs nanohybrids used as a lithium-ion-battery anode exhibits a higher reversible capacity of 1045 mA h g−1 at 0.5 A g−1 after 300 cycles as well as a high-rate cycling stability after 1000 cycles. The enhanced performance can be attributed to the wonderful merits of the external carbon protective shell for preserving the integrity of the overall electrode, and the internal porous carbon skeleton for inhibiting the aggregation and electrical isolation of the active particles during cycling.
    No preview · Article · Aug 2015 · Particle and Particle Systems Characterization
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    ABSTRACT: To cure serious bone tuberculosis, a novel long-term drug delivery system was designed and prepared to satisfy the needs of both bone regeneration and antituberculous drug therapy. The antituberculous drug (rifampicin, RFP) was loaded into a porous scaffold, which composed of a new designed polylactone, poly(ε-caprolactone)-block-poly(lactic-co-glycolic acid) (b-PLGC) copolymer, and β-tricalcium phosphate (β-TCP). The releasing results demonstrated that RFP could be steadily released for as long as 12 weeks both in vitro and in vivo. Within the in vivo experimental period, the drug concentration in tissues surrounding implants was much higher than that of in blood which was still superior to the effective value to kill mycobacterium tuberculosis. MC3T3-E1 osteoblasts proliferated well in extracts and co-culture on composite scaffolds, indicating good biocompatibility and cell affinity of the scaffold. The results of rabbit radius repair experiment displayed the scaffold has good bone regeneration capacity. The RFP-loaded b-PLGC/TCP composite scaffold thus could be envisioned to be a potential and promising substrate in clinical treatment of bone tuberculosis.
    No preview · Article · Jul 2015
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    ABSTRACT: Multi walled carbon nanotubes decorated with ferriferrous oxide nanoparticle (MWCNTs-Fe3O4) complex was used as an effective reinforcement in the polymer composites. The MWCNTs-Fe3O4 with various grafting contents of Fe3O4 nanoparticles were successfully prepared by combining in situ atom transfer radical polymerization (ATRP) and coprecipitation process, which was characterized with Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). The MWCNTs-Fe3O4 complex showed the strong magnetic response behavior, which could be easily aligned in an external magnetic field. The alignment state of MWCNTs-Fe3O4 complex could be modulated by adjusting the intensity of external magnetic field, grafting content of Fe3O4 nanoparticles and viscosity of the solvent. Moreover, with the addition of MWCNTs-Fe3O4, tensile strength and modulus of epoxy composites were enhanced by 12.3 and 10.9%, respectively, which was due to the reinforcing effect of the aligned MWCNTs-Fe3O4 within magnetic field.
    No preview · Article · Jul 2015 · IOP Conference Series Materials Science and Engineering
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    Full-text · Dataset · Jul 2015
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    Full-text · Dataset · Jul 2015
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    ABSTRACT: Bioactive glass (BG) decorated nanoporous composite carbon nanofibers (PCNF/BG) were prepared for the purpose of obtaining effective substrates for skeletal tissue regeneration. The preparation was conducted by electrospinning of polyacrylonitrile (PAN)/polymethylmethacrylate (PMMA) blends with addition of sol-gel precursors of 58s-type (mol%: 58 %SiO2-38 %CaO-4 %P2O5) BG, followed by high temperature thermal treatment. The removal of PMMA during the carbonization of PAN generated numerous slitlike nanoporous structure along CNFs, leading to a significant enhancement in specific surface area, surface roughness and pore volume, which were confirmed by characterizations of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). PCNF/BG composites with different specific surface areas were biologically evaluated by experiments of biomineralization in simulated body fluid (SBF), in vitro MC3T3-E1 osteoblasts proliferation and osteogenic differentiation. Compared to non-porous CNF/BG, the nanoporous structure distinctively enlarged the interfacial reaction area of BG component with medium environment and thus enhanced the bioactivity of CNFs by accelerating the dissolution of BG component and providing abundant nucleation sites for hydroxyapatite depositions. The released ions displayed distinct promotion in proliferation and osteogenic differentiation of osteoblasts cells, which promoted the osteocompatibility of carbon-based materials significantly.
    No preview · Article · May 2015

Publication Stats

549 Citations
211.01 Total Impact Points

Institutions

  • 2016
    • Peking University
      Peping, Beijing, China
  • 2005-2016
    • Beijing University of Chemical Technology
      • College of Materials Science and Engineering (SMSE)
      Peping, Beijing, China
  • 2013
    • Tsinghua University
      • State Key Laboratory of New Ceramics and Fine Processing
      Peping, Beijing, China
  • 2008-2011
    • Second Military Medical University, Shanghai
      Shanghai, Shanghai Shi, China
  • 2006-2008
    • Changhai Hospital, Shanghai
      Shanghai, Shanghai Shi, China