A new hydrophilic polymer for biomaterial coatings with low protein adsorption

BIOPOL polyurethane polymers, an extension of the HYPOL Polymer series of foamable hydrophilic polymers, have been developed which exhibit improved performance for selected biomedical applications. Members of the BIOPOL polyurethane polymer series, with molecular weights in the range of 7000 to 30,000, are larger molecules than HYPOL polymers (MW less than 3000) and produce hydrogels, rather than foams, when mixed with water. The prototype material in this series, BIOPOL XP-5, is a liquid prepolymer which chain extends in water and forms a hydrogel which can contain greater than 85% water. The time required for polymerization with water was dependent on the prepolymer: water ratio. This prepolymer was coated onto silica and medical grade tubing and then cured in place with water to form a stable coating which was resistant to non-specific protein binding. In addition, soluble, isocyanate-free forms of the prepolymer were tested for toxicity and shown to produce no adverse effects when injected intravenously into mice or when applied to a chicken chorioallantoic membrane. BIOPOL polymers can be useful in applications where protein adsorption is an undesirable event.