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CONTENTS
Volume 1, Number 1, March 2014
 

Abstract
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Key Words
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Address
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Abstract
Polymer multilayered hydrogels were prepared on a titanium alloy (Ti) substrate using a layer-by-layer (LBL) process to load a cell growth factor. Two water-soluble polymers were used to fabricate the multilayered hydrogels, a phospholipid polymer with both N, N-dimethylaminoethyl methacrylate (DMAEMA) units and 4-vinylphenylboronic acid (VPBA) units [poly(MPC-co- DMAEMA-co-VPBA) (PMDV)], and the polysaccharide alginate (ALG). PMDV interacted with ALG through a selective reaction between the VPBA units in PMDV and the hydroxyl groups in ALG and through electrostatic interactions between the DMAEMA units in PMDA and the anionic carboxyl groups in ALG. First, the Ti substrate was covered with photoreactive poly vinyl alcohol, and then the Ti alloy was alternately immersed in the respective polymer solutions to form the PMDV/ALG multilayered hydrogels. In this multilayered hydrogel, vascular endothelial growth factor (VEGF) was introduced in different layers during the LbL process under mild conditions. Release of VEGF from the multilayered hydrogels was dependent on the location; however, release continued for 2 weeks. Endothelial cells adhered to the hydrogel and proliferated, and these corresponded to the VEGF release profile from the hydrogel. We concluded that multilayered hydrogels composed of PMDV and ALG could be loaded with cell growth factors that have high activity and can control cell functions. Therefore, this system provides a cell function controllable substrate based on the controlled release of biologically active proteins.

Key Words
multilayered hydrogels; phospholipid polymer; proliferation; growth factor protein

Address
Jiyeon Choi and Kazuhiko Ishihara: Department of Materials Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
Tomohiro Konno and Kazuhiko Ishihara: Department of Bioengineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Abstract
In the current study, a drug-eluting stent coated with biodegradable polymers and sirolimus was developed by using an ultrasonic nanocoater and characterized in aspects of surface smoothness and coating thickness. In addition, in vitro release profiles of sirolimus by changing top coating layer with different biodegradable polymers were investigated. Smooth surfaces with variable thickness could be fabricated by optimizing polymer concentration, flow rate, nozzle-tip distance, gas pressure, various solvents and ultrasonic power. Smooth surface could be generated by using volatile solvents (acetone, chloroform, and methylene chloride) or post-treating with solvent vapor. Coating thickness could be controlled by varying injection volume or polymer concentration, and higher concentration could reduce the coating time while obtaining the same thickness. The thickness measurement was the most effectively performed by a conventional cutting method among three different methods that were investigated in this study. Release profiles of sirolimus were effectively controlled by changing polymers for top layer. PLGA made the release rate 3 times faster than PDLLA and PLLA and all top layers prevented burst release at the initial phase of profiles. Our results will provide useful and informative knowledge for developing drug-eluting stents, especially coated with biodegradable polymers.

Key Words
biodegradable polymer; drug-eluting stent; ultrasonic coating; sirolimus; controlled release

Address
Yoon Ki Joung, Bu Nam Jang, Jong Hee Kang and Dong Keun Han: Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea

Abstract
We have previously described a new multilayer alginate microcapsule system, and the goals of the present study were to assess the in vitro function of islets encapsulated in its inner layer, and the angiogenic ability of FGF-1 delivered from the external layer in an omentum pouch. Following isolation and culture, islets were encapsulated in the inner core of microspheres (500 - 600 µm in diameter) with a semi-permeable poly-L-ornithine (PLO) membrane separating two alginate layers, and both unencapsulated and encapsulated islet function was assessed by a dynamic glucose perifusion. For angiogenesis experiments, one group of microcapsules without FGF-1 (control) and another (test) containing FGF-1 with heparin encapsulated in the external layer were made. One hundred microcapsules of each group were transplanted in Lewis rats (n = 5⁄group) and were retrieved after 14 days for assessment of angiogenesis. Glucose perifusion of unencapsulated and encapsulated islets resulted in similar stimulation indices. The release of FGF-1 resulted in increased vascular density compared to controls. In conclusion, islets encapsulated in the core of multilayer alginate microcapsules maintain functionality and the microcapsule’s external layer is effective in delivery of FGF-1 to enhance graft neovascularization in a retrievable omentum pouch.

Key Words
microcapsule; islet; angiogenesis; drug delivery; transplantation

Address
J.P. McQuilling, R. Pareta, S. Sivanandane G. Orlando, A.C. Farney and E.C. Opara: Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
O. Khanna, B. Jiang, E.M. Brey Pritzker: Institute of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60630, USA

Abstract
Gold nanorod’s exceptional light to heat transduction is a robust phonomenon that has been extensively verified. The phenomenon is a trait from which many novel applications across disciplines have been proposed. In this investigation, the feasibility of utilizing heat harvested from such photothermal method to combat cancer is presented. Using non-invasive laser methods, an in vivo study is conducted on mouse ear tumors administered with gold nanorods (Au NRs). An emphasis is placed on monitoring the tumor developments after photothermal treatments, over time. The findings reveal significant tumor growth surpression at a threshold laser power of 0.6 W⁄cm2 lasting 2 minutes; this energy also brought about dramatic size reduction in treated tumors. Furthermore, the apparent formation of an eschar over the laser treated region indicates extensive hemorrhagic necrosis of the tumor tissue; a phenomenon implicative to the inhibition of angiogenesis.

Key Words
gold nanorod; photothermal; tumor; laser; cancer; necrosis

Address
Bruce Yao Wen Liu, Cheng-Lung Chen, Shin-Yu Lee and Yang-Yuan Chen: Institute of Physics, Academia Sinica, Taipei, Taiwan
Bruce Yao Wen Liu and Chih-Ta Chia: Department of Physics, National Taiwan Normal University, Taipei, Taiwan
Fu-Hsiung Chang: Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan
Win-Li Lin: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
Yang-Yuan Chen: Graduate Institute of Applied Physics, National Chengchi University, Taipei, Taiwan

Abstract
The purpose of this experiment was to evaluate the apatite-formation abilities of low-modulus Ti-7.5Mo substrates treated with NaOH aqueous solutions and subsequent ethyl alcohol aging before soaking them in simulated body fluid. Specimens of Ti-7.5Mo were initially treated with 5 M NaOH at 60°C for 24 h, resulting in the formation of a porous network structure composed of sodium hydrogen titanate. Afterwards, the specimens were aged in ethyl alcohol at 60°C for 5 or 10 min, and subsequently immersed in simulated body fluid at 37°C for 3, 7 and 14 days. Ethyl alcohol aging significantly increased the apatite-forming abilities of Ti-7.5Mo. The amount of apatite deposited on the Ti-7.5Mo after NaOH treatment and subsequent ethyl alcohol aging was much greater, especially after the Ti-7.5Mo specimens were aged for 5 min. Due to its excellent combination of bioactivity, low elastic modulus and low processing costs, the Ti-7.5Mo treated with NaOH aqueous solutions and subsequently aged in ethyl alcohol has promising heavy load-bearing applications.

Key Words
Titanium alloys; Alkali treatment; Ethyl alcohol aging; Apatite; Simulated body fluid

Address
Wen-Fu Ho and Shao-Hsuan Chuang: Department of Materials Science and Engineering, Da-Yeh University, Taiwan
Hsi-Kai Tsou: Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan
Shih-Ching Wu, Shih-Kuang and Hsu Hsueh-Chuan Hsu: Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan; Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science and Technology, Taiwan


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