Jian Tang

Fudan University, Shanghai, Shanghai Shi, China

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Publications (9)28.57 Total impact

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    ABSTRACT: Surface patterning is very useful in biomaterial studies, yet it is not easy to prepare a micropattern with cell-adhesion contrast that is stable in a wet environment. Recently, a platform technique of transfer photolithography was invented to fabricate stable metal microarrays on the surface of a cell-adhesion resistant and mechanically biomimetic poly(ethylene glycol) hydrogel; the linker is the key chemical in such a transfer strategy. This article reports the design and synthesis of a hetero-bifunctional macromonomer linker with a thiol group at one end and an acryloyl group at the other end. The bifunctional linker was characterized by GPC and 1H NMR, and the average number of thiol groups in the bifunctional linker was detected by Ellman’s reagent. The regent stability under wet conditions was also confirmed by the model reactants. The resultant micropatterned surfaces are meaningful for future studies of cell behaviors on mechanically biomimetic matrixes.
    Science China-Chemistry 04/2014; 57(4):645-653. DOI:10.1007/s11426-013-5057-8 · 1.52 Impact Factor
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    ABSTRACT: Magnesium (Mg) or its alloys have shown great potential as promising biocorrosive or biodegradable implantation materials and/or internal fixators, owing to their good biocompatibility and osteoinductive potential. However, poor anticorrosion property or rapid biodegradation has limited their clinical applications where initial mechanical stabilisation is required. One of the practical approaches for decreasing its biodegradation is to introduce a coating on Mg or its alloys. The current study compared the two most widely used coating techniques, i.e., microarc oxidation (MAO) and electrophoresis deposition (EPD), for coating onto the Mg–Zr pin surface, both in vitro and in vivo, to determine which method can prevent Mg–Zr alloy degradation better. In vitro pH measurement and in vivo microcomputed tomographic evaluation were used for determining its degradation rate. Our in vitro and in vivo testing results indicated that EPD demonstrated better corrosion resistance than MAO, implying the potential of electrochemical technology for surface modification of Mg or its alloys developed for orthopaedic applications.
    10/2013; 1(1):41–48. DOI:10.1016/j.jot.2013.06.003
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    ABSTRACT: Magnesium alloys have been advocated as potential artificial bone materials due to their biocompatibility and biodegradability. The understanding of their corrosive mechanism in physiological environments is therefore essential for making application-orientated designs. Thus, this in vitro study was designed to assess the effects of CO2 on corrosive behavior of AZ31D to mimic in vivo special ingredient. Electrochemical technologies accompanied with Scanning electron microscope, Fourier transform infrared, X-ray diffraction, Energy dispersive spectroscopy and hydrogen evolution measurement were employed to analyze corrosive rates and mechanisms of AZ31D. Moreover, the biocompatibility of AZ31D was assessed with a direct cell attachment assay and an indirect cytotoxicity test in different diluted extracts. The ion concentrations in extracts were measured using inductively coupled plasma mass spectrometry to offer explanations on the differences of cell viability in the indirect test. The results of the direct cytotoxicity assay showed that the corrosive rate of AZ31D was too rapid to allow for cell adhesion. Extracts diluted less than 20 times would cause adverse effects on cell proliferation, likely due to excessive ions and gas release. Moreover, the presence of CO2 did not cause significant differences on corrosive behavior of AZ31D according to the results of electrochemical testing and hydrogen evolution measurement. This might be caused by the simultaneous process of precipitation and dissolution of MgCO3 due to the penetration role of CO2. This analysis of corrosive atmospheres on the degradation behavior of magnesium alloys would contribute to the design of more scientific in vitro testing systems in the future.
    10/2013; 33(7):4416-26. DOI:10.1016/j.msec.2013.06.041
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    ABSTRACT: As a bioabsorbable metal with mechanical properties close to bone, pure magnesium or its alloys have great potential to be developed as medical implants for clinical applications. However, great efforts should be made to avoid its fast degradation in vivo for orthopedic applications when used for fracture fixation. Therefore, how to decease degradation rate of pure magnesium or its alloys is one of the focuses in Research and Development (R&D) of medical implants. It has been recognized that surface modification is an effective method to prevent its initial degradation in vivo to maintain its desired mechanical strength. This article reviews the recent progress in surface modifications for prevention of fast degradation of magnesium or its alloys using in vitro testing model, a fast yet relevant model before moving towards time-consuming and expensive in vivo testing. Pros and cons of various surface modifications are also discussed for the goal to design available products to be applied in clinical trials.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 08/2012; 100(6):1691-701. DOI:10.1002/jbm.b.32707 · 2.33 Impact Factor
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    ABSTRACT: Herein we examined an adipogenic or osteogenic induction of rat bone marrow mesenchymal stem cells (MSCs) in the corresponding media and a co-induction in a 1:1 mixed medium. The cell size effect and cell-cell contact effect were employed as two demonstrations to check the similarity or difference of the effects under these two induction ways. We seeded cells on a micropatterned surface with cell-adhesive microislands on poly(ethylene glycol) hydrogels. MSCs were well localized on the microislands separated by the strong and persistent non-fouling background, which enabled the observations of individual cells of varied sizes and numbers. We made statistics of adipogenic and osteogenic differentiations of single MSCs of different sizes (170-5600 μm(2)) and also of cell clusters of different aggregation numbers (1, 2, 4 and 8 etc.) with small, medium or large cell sizes. Both sole induction and co-induction led to monotonic cell size effects: small cells favored the adipogenic differentiation, and large cells preferred to the osteogenic differentiation. The effects of cell-cell contact were, however, rather complicated: the aggregation among cells was beneficial for both adipogenic and osteogenic differentiations, as revealed from the sole inductions; but under the co-induction culture in the mixed medium, the inherent enhancement of differentiation by the cell-cell contact encountered competition between the adipogenic and osteogenic commitments. We also examined the effects of cell density, which involved both size and contact effects, and thus exhibited different behaviors under sole induction and co-induction as well. We revealed that the density effect reflected the cooperation (for adipogenic differentiation) or competition (for osteogenic differentiation) between cell size and cell-cell contact effects.
    Biomaterials 06/2012; 33(26):6008-19. DOI:10.1016/j.biomaterials.2012.05.010 · 8.31 Impact Factor
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    ABSTRACT: New drug exploration is difficult in a clinical setting and the development of new drugs may be costly and time consuming. With further research into the pathological mechanisms and etiology of diseases as well as the rapid development of biological techniques, many 'old drugs' that have been applied in clinics may have new therapeutic functions which may shed light on clinical management. Based on this, we have investigated the 'old drugs for new applications' strategy in pharmacology which may be less expensive and more efficient in the clinical setting. In this paper we have explored and illustrated the potential applications of 'old drugs' for the treatment of orthopedic diseases, especially in arthritis and osteoporosis therapy.
    Therapeutic advances in musculoskeletal disease 08/2011; 3(4):201-5. DOI:10.1177/1759720X11408487
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    ABSTRACT: Micro-nano patterns of gold on the surface of poly(ethylene glycol) (PEG) hydrogels were prepared. The approach combines the technique of conventional photolithography (a top-down method for micropatterns), block copolymer micelle nanolithography (a bottom-up method for gold nanopatterns), and a linker-assistant technique to transfer a pattern on a hard surface to a polymeric surface. Hybrid micro-nano patterns on hydrogels were characterized using scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The patterned Au nanoparticles were further modified by a peptide containing arginine-glycine-aspatate (RGD). The cell-adhesion contrast of the patterned hydrogel surface was confirmed by preliminary cell experiments.
    Nanoscale 01/2010; 2(1):122-7. DOI:10.1039/b9nr00124g · 6.74 Impact Factor
  • Jian Tang, Rong Peng, Jiandong Ding
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    ABSTRACT: Using the material technique recently developed by us, we prepared a micropattern on poly(ethylene glycol) (PEG) hydrogel to keep background resistant to cell adhesion for a long time, which made examination of differentiation of localized stem cells available. Our micropattern designed in this paper prevented or ensured contact between cells adhering in arginine-glycine-aspartic acid (RGD) microdomains, and thus afforded a unique way to study the effects of cell-cell contact on the lineage differentiation of stem cells while ruling out the interference of soluble factors or cell seeding concentration etc. As demonstration, mesenchymal stem cells derived from rats were examined in this study, and both osteogenic and adipogenic differentiations were found to be regulated by cell-cell contact. Isolated cells exhibited less significant differentiation than paired or aggregated cells. For those stem cells in contact, the extent of differentiation was fairly linearly related to the extent of contact characterized by coordination number. Additionally, we revealed the existence of some unknown cues besides gap junction responsible for such effects of cell-cell contact.
    Biomaterials 12/2009; 31(9):2470-6. DOI:10.1016/j.biomaterials.2009.12.006 · 8.31 Impact Factor
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    ABSTRACT: Stripe-micropatterned surfaces have recently been a unique tool to study cell orientation. In this paper, we prepared, by the photolithography transfer technique, stable gold (Au) micropatterns on PEG hydrogel surfaces with defined cell-resistant (PEG hydrogel) and cell-adhesive (gold microstripes) properties. 3T3 fibroblasts were cultured on Au-microstripe surfaces to observe cell adhesion and orientation. Five statistical parameters were defined and used to describe cell orientation on micropatterns. With the increase of inter-stripe distance, the orientational order parameter, the ratio of long and short axes of a cell, and the occupation fraction of cells on stripes increased gradually, whereas the spreading area of a single cell decreased. The abrupt changes of these four parameters did not happen at the same inter-distance. The adhesion ratio of a cell on Au stripes over cell spreading area did not change monotonically as a function of inter-stripe distance. The combination of the 5 statistical parameters represented well the cell orientation behaviors semi-quantitatively.
    Chinese Science Bulletin 09/2009; 54(18):3154-3159. DOI:10.1007/s11434-009-0240-1 · 1.37 Impact Factor

Publication Stats

214 Citations
28.57 Total Impact Points

Institutions

  • 2009–2014
    • Fudan University
      • Department of Macromolecular Science
      Shanghai, Shanghai Shi, China
  • 2012
    • Chinese Academy of Sciences
      • Institute of Biomedical Engineering and Health Technology
      Peping, Beijing, China