Berkeley, CA, United States
Berkeley, CA, United States

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Yamaoka T.,Japan National Cardiovascular Center Research Institute | Yamaoka T.,Chiyoda Corporation | Njatawidjaja E.,Japan National Cardiovascular Center Research Institute | Njatawidjaja E.,Chiyoda Corporation | And 8 more authors.
Polymer Degradation and Stability | Year: 2013

Tissue adhesions cause severe and life-threatening conditions, including pain, infertility, and heart defects. The purpose of this study is to develop an anti-adhesion membrane that sticks onto the injured tissues or organs in order to avoid the suturing of the membrane which may lead to the unnecessary tissue adhesion. We previously developed poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) multiblock copolymers as soft, water absorbable, and quickly degradable biomaterials. The copolymer with the highest PEG content adsorbs body fluid in vivo and sticks to the tissues. In the present study thin film and nanofiber mat were prepared from the copolymer and evaluated in vitro and in vivo. The hydrophilicity and the degradation rate increased with the increased PEG content of the multiblock copolymers. The copolymer with PEG content of 88% (LE(m)-88) was quickly swollen, become viscous, and rapidly collapsed in PBS, which was suitable feature for adhesion prevention material without suturing. Various double layered membranes with different characteristics were evaluated in vivo by applying onto the cecum scrubbed with abrasive paper, and onto the heart surface after pericardium removal. LE(m)-88 was swollen with tissue fluid and had a hydrogel-like nature. LE(m)-88 film/LE(m)-32 film double layered membrane was found to be the most effective in preventing tissue adhesion in cecum model. This excellent performance was confirmed in the rat heart adhesion model. In both models, the LE(m)-32 support film was detached from the site of application, which leads to the healing without adhesion. © 2013 Elsevier Ltd.

Dempsey D.K.,Texas A&M University | Schwartz C.J.,Texas A&M University | Ward R.S.,Polymer Technology Group Inc. | Iyer A.V.,Polymer Technology Group Inc. | And 2 more authors.
Macromolecular Materials and Engineering | Year: 2010

A novel technique was developed to control the deposition of electrospun polyurethane fibers using a silicone collector substrate patterned with soft lithography. This method can be used to control selective fiber deposition with broad pattern dimensions (50-500 μm) over a large area. The combination of ease of use, low cost, tunability, and generation of relatively large fiber mats available with this technique is expected to advance our ability to mimic the orientation and anisotropic properties of native tissues to generate improved tissue engineering scaffolds. Electrospun polyurethane fibers can be patterned by controlling the surface topography of a silicone collector substrate using soft lithography. Fiber patterning is expected to advance our ability to mimic the orientation and anisotropic properties of native tissues to generate improved tissue engineering scaffolds. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Weidner T.,University of Washington | Samuel N.T.,University of Washington | Samuel N.T.,CIBA VISION Corporation | McCrea K.,Polymer Technology Group Inc. | And 3 more authors.
Biointerphases | Year: 2010

The structure, orientation, and formation of amphiphilic α-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation SFG vibrational spectroscopy, near-edge x-ray absorption fine structure NEXAFS spectroscopy, and x-ray photoelectron spectroscopy XPS. The -helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid amphiphilic peptide with leucine and lysine side chains located on opposite sides. XPS composition analysis confirms the formation of a peptide film that covers about 75% of the surface. NEXAFS data are consistent with chemically intact adsorption of the peptides. A weak linear dichroism of the amide φ is likely due to the broad distribution of amide bond orientations inherent to the -helical secondary structure. SFG spectra exhibit strong peaks near 2865 and 2935 cm- related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 and 3400 cm- indicate ordering of water molecules in the adsorbed-peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm- confirm that the secondary structure is preserved in the adsorbed peptide. A kinetic study of the film formation process using XPS and SFG showed rapid adsorption of the peptides followed by a longer assembly process. Peptide SFG spectra taken at the air-buffer interface showed features related to well-ordered peptide films. Moving samples through the buffer surface led to the transfer of ordered peptide films onto the substrates. © 2010 American Vacuum Society.

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