Hydrophilic coatings applied to guidewires or catheters, lower friction of the device thus improves handling and reduces damage to the vessel walls during access, delivery and retrieval. Peripheral guidewires typically consist of a polymer jacket, basecoat and topcoat. The polymer jacket is highly radiopaque for fluoroscopy visualization. Basecoat adheres to the polymer jacket and hydrophilic topcoat. Basecoat and topcoat play important roles towards coating device durability and lubricity.
Water Loving Coatings (WLC) are the first developed 510(k) clearance guidewires utilizing epoxy polyurethane technology. Coatings are non-hemolytic and non-cytotoxic. WLC are advances toward glycidyl carbamate (GC) resins. Linear Glycidyl Carbamates have shown excellent flexibility based off structure property relationships . Water dispersible GC (WD-GC) oligomers have been prepared by additions of poly(ethylene glycol) methyl ether (m-peg) to isocyanurate and biuret, then end capped with glycidol . WLC technologies are lubricious and durable water dispersible polyurethane or polyurea glycidyl carbamates . Modified Hyaluronate with WD-GC oligomers have shown increases in lubricity of Guidewires when used with a catheter . WLC coatings have been applied to a micro-wire to reduce endothelial mechanical lining damage .
Common thermoplastic urethanes (TPU), similar to WLC morphology, used in the medical industry, are: Biomer and Lubrizol’s Pellethane®, Tecoflex™ and Estane™. Biomer consists of 4,4′-Methylenebis(phenyl isocyanate) (MDI), Ethylenediamine (EDA), and Polytetramethylene diol (Poly THF). Pellethane consists of MDI, 1,4-Butanediol (BDO) and Poly THF. Tecoflex consists of 4-4′-methylenebis (cyclohexyl isocyanate) (H12MDI), BDO and Poly THF. Medical grade Estane is an ester of adipic acid with BDO for soft segments and MDI and BDO for hard segments. TPU structure and morphology dictates polymeric properties.