Irreversible immobilization of enzymes into polyurethane coatings
A method of irreversibly immobilizing an enzyme in a polyurethane and an enzyme-containing polyurethane having a degree of immobilization of the enzyme of approximately 100%. The synthesis of waterborne polyurethanes in the presence of enzyme has enabled the irreversible attachment of the enzyme to the polymeric matrix. The distribution of immobilized enzyme as well as activity retention are homogeneous within the polyurethane. Decreasing ECC hydrophobicity, via the use of a less hydrophobic polyisocyanate prepolymer during polymerization, significantly enhanced the intrinsic activity of the ECC.
1. An enzyme-containing polyurethane made by the process comprising the steps of:
(a) reacting a mixture of (i) a polyol dispersion coreactant and (ii) an enzyme to create an aqueous mixture;
(b) adding a water-dispersible polyisocyanate based on hexamethylene diisocyanate to the aqueous mixture
(c) allowing the polyisocyanate and aqueous mixture to form a dispersion;
(d) applying the dispersion onto a substrate to produce an enzyme-containing polyurethane; and
(e) curing the enzyme-containing polyurethane.
2. The enzyme-containing polyurethane made by the process of claim 1 in which the weight ratio of polyol dispersion to polyisocyanate added in step (b) is approximately 2.
3. The enzyme-containing polyurethane made by the process of claim 2 in which the polyol dispersion used in step (a) has a water content of approximately 70 wt. %.
4. The enzyme-containing polyurethane made by the process of claim 3 in which a polyethylene modified polydimethyl siloxane surfactant is present during step (a).
5. The enzyme-containing polyurethane made by the process of claim 4 in which a bis-tris propane buffer and CaCl 2 are present during step (a).
6. The enzyme-containing polyurethane made by the process of claim 5 in which the mixture reacted in step (c) includes 2.5 times by weight as much of the polyol dispersion coreactant as polyisocyanate.
7. The enzyme-containing polyurethane made by the process of claim 6 in which diisopropylfluorophosphatase is included as the enzyme in step (a).
8. The enzyme-containing coating made by the process of claim 7 having a degree of immobilization of the diisopropylfluorophosphatase of approximately 100%.
9. The enzyme-containing polyurethane made by the process of claim 1 having between 10% and 100% activity retention.