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Berkeley, CA, United States

Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2002

DESCRIPTION (provided by applicant):It is well known that the thrombo-resistance of polymeric biomaterials can be improved by surface endpoint immobilization of heparin. Current heparinization methods are complex and costly, and may degrade the mechanical properties of the base polymer. The proposed study will determine the feasibility of synthesizing tough, thermoplastic polyurethane biomaterials with 'built-in' binding sites for heparin. Heparinization will be achieved by simply soaking the device/component made from the subject polymer, in an aqueous heparin solution. A diamine-diamide-diol (PIME), which has an established ability to bind heparin, will replace some of the normal diol 'chain extender' in a well-established biomedical polycarbonate-urethane. Surfaces of the resulting PIME-containing polyurethanes will be characterized by Sum Frequency Generation Spectroscopy (SFG), Contact Angle Goniometry, and Atomic Force Microscopy. Heparin activity will be determined by Activated Partial Thromboplastic Time (APTT) on freshly synthesized and sterilized device analogues. Preliminary results indicate surface PIME can be easily distinguished from the base polyurethane by SFG. Also, non-sterile heparinized PIME-containing polyurethanes exhibit an APTT of >500 seconds compared to

Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 0.00 | Year: 2001

DESCRIPTION (Verbatim from the Applicant's Abstract): The application of biomaterials science to devices now in development would benefit from the availability of well-characterized polymers with step wise variable surface composition. Control of surface chemistry bulk composition has utility in tissue engineering, in fabrication of conventional medial devices and in new nanotechnology application of polymers. In Phase we confirmed that, while rates are slower, equilibrium surface tension/composition of polymer blends is quantitatively similar to conventional surfactants in liquid Solvents. Energy minimization drives surface equilibration, which depends on the nature of the interface, e.g., air vs. blood. Phase II involves preparation of three series of polymer blends with varying surface composition, each with a different surface modifying end group: silicone, fluorocarbon, polyethyleneoxide. Each series will be characterized by several surface-sensitive methods including Sum Frequency Generation Spectroscopy, XPS, AFM and surface tension/wettability. Each characterized series will be subjected to a battery of short-term in vitro biological tests including (competitive) protein adsorption and complement activation. The hypothesis to be testes is that biological response will vary monotonically with surface chemistry when the surface chemistry is determined by truly surface-sensitive methods and knowledge of the kinetics of polymer surface rearrangement following upon immersion of air-equilibrated surfaces into aqueous fluids. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE

Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 78.52K | Year: 1997


Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2004

DESCRIPTION (provided by applicant): Endpoint immobilization of heparin on the surface of polymeric biomaterials is a well-established method for improving thrombo-resistance. The most effective currently-available heparinization methods are costly, mu

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.

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. Source

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