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Hydrophilic Coating (hydrophilic + coating)
Selected AbstractsHeparin release from slippery-when-wet guide wires for intravascular useJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 6 2002Camiel C. L. Peerlings Abstract Thin metallic wires with an adherent hydrophilic/ lubricious polymeric coating were manufactured in a new extrusion-like procedure. This procedure is part of a novel and efficient way of assembling lubricious guide wires for intravascular interventions, such as percutaneous transluminal angioplasty. It is reported that heparin can readily be incorporated in the hydrophilic coating. A set of heparin-containing guidewire models was made and studied in detail. This showed that (i) immersion of the guide-wire models in an aqueous environment leads to release of heparin from their surface; (ii) the presence of heparin in the coating does not impede the lubricity of the coils; (iii) addition of stearic acid in the coating, next to heparin, does not influence the lubricity of the guide-wire models. Two different charges of heparin (designated heparin-low and heparin-high) were incorporated in the coating. It is discussed that release of heparin from the surface of medical devices (e.g. guide wires and catheters) is much more effective than systemic heparinization, basically because dissolved heparin molecules have a much larger probability of simply passing a medical device's surface (axial convection) rather than contacting it (radial diffusion). © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 692,698, 2002 [source] Quantification of chemical,polymer surface interactions in microfluidic cell culture devicesBIOTECHNOLOGY PROGRESS, Issue 2 2009Hui Xu Abstract Microfluidic cell culture devices have been used for drug development, chemical analysis, and environmental pollutant detection. Because of the decreased fluid volume and increased surface area to volume ratio, interactions between device surfaces and the fluid is a key element that affects the performance and detection accuracy of microfluidic devices, particularly if fluid is recirculated by a peristaltic pump. However, this issue has not been studied in detail in a microfluidic cell culture environment. In this study, chemical loss and contaminant leakage from various polymer surfaces in a microfluidic setup were characterized. The effects of hydrophilic coating with Poly (vinyl alcohol), Pluronic® F-68, and multi-layer ionic coating were measured. We observed significant surface adsorption of estradiol, doxorubicin, and verapamil with PharMed® BPT tubing, whereas PTFE/BPT and stainless steel/BPT hybrid tubing caused less chemical loss in proportion to the fraction of BPT tubing in the hybrid system. Contaminants leaching out of the BPT tubing were found to be estrogen receptor agonists as determined by estrogen-induced green fluorescence expression in an estrogen responsive Ishikawa cell line and also caused interference with an estradiol enzyme-linked immunosorbent assay (ELISA) assay. Stainless steel/BPT hybrid tubing caused the least interference with ELISA. In summary, polymer surface and chemical interactions inside microfluidic systems should not be neglected and require careful investigations when results from a microfluidic system are compared with results from a macroscale cell culture setup. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Confinement effects on the morphology of photopatterned porous polymer monoliths for capillary and microchip electrophoresis of proteinsELECTROPHORESIS, Issue 14 2008Mei He Abstract We find that the morphology of porous polymer monoliths photopatterned within capillaries and microchannels is substantially influenced by the dimensions of confinement. Porous polymer monoliths were prepared by UV-initiated free-radical polymerization using either the hydrophilic or hydrophobic monomers 2-hydroxyethyl methacrylate or butyl methacrylate, cross-linker ethylene dimethacrylate and different porogenic solvents to produce bulk pore diameters between 3.2 and 0.4,µm. The extent of deformation from the bulk porous structure under confinement strongly depends on the ratio of characteristic length of the confined space to the monolith pore size. The effects are similar in cylindrical capillaries and D-shaped microfluidic channels. Bulk-like porosity is observed for a confinement dimension to pore size ratio >10, and significant deviation is observed for a ratio <5. At the extreme limit of deformation a smooth polymer layer ,300 nm thick is formed on the surface of the capillary or microchannel. Surface tension or wetting also plays a role, with greater wetting enhancing deformation of the bulk structure. The films created by extreme deformation provide a rapid and effective strategy to create robust wall coatings, with the ability to photograft various surface chemistries onto the coating. This approach is demonstrated through cationic films used for electroosmotic flow control and neutral hydrophilic coatings for electrophoresis of proteins. [source] Grafting CVD of Poly(vinyl pyrrolidone) for Durable Scleral Lens Coatings,CHEMICAL VAPOR DEPOSITION, Issue 1-3 2010Kyra L. Sedransk Abstract Grafting (g)CVD from the monomer 1-vinyl-2-pyrrolidone (VP) and the Type II initiator benzophenone (BP) under 254,nm UV irradiation yields durable hydrophilic coatings on substrates of poly(methacrylic acid) (PMA) derivatives, desirable for scleral lens applications. The gCVD polymerization of the VP monomer is essentially complete, and little excess BP remains in the film. Process optimization, through single variable and two fractional factorial experiments, result in retention of >90% of the as-deposited film thickness after rinsing. Increasing the initiator dosing time beyond 10,min, or the UV exposure time beyond 5,min, has little effect on the as-deposited thickness, or percentage of film retained after rinsing. This suggests that UV irradiation rapidly transforms most of the BP absorbed on the surface to initiating radicals. Once sufficient initiator dosage and UV exposure have been achieved, the initial deposition thickness is controlled primarily by the total flux of monomer to the surface, which is consistent with previous studies. For all samples, thickness loss occurs primarily during the first 30 days of saline soak-testing with no statistically significant loss (p,>,0.25) during the next 90 days of soak testing. While the additional UV exposure time has a limited effect on initial film thickness, it does increase long term thickness retention, most likely by forming crosslinked and branched structures within the film. All samples tested retain sufficient gCVD coating thickness to impart improved hydrophilicity at the surface throughout the entire 120 day saline soak-testing period. The fractional factorial experiments correlate improved hydrophilicity with an interaction between initiator dosage time and UV exposure time. Indeed, decreasing these two process variables in tandem provides the greatest reduction in contact angle. While the uncoated PMA displayed 92.3°,±,2.1° advancing and 86.7°,±,3.0° receding contact angles with water, the most hydrophilic gCVD coating lowers the advancing and receding contact angles to 39.5°,±,2.6° and 36.2°,±,1.6°, respectively. [source] | |||||||||||||