| Abstract [eng] |
Porous poly(urethane urea) (PUU) microparticles from biodegradable, biocompatible and hydrophilic poly(vinyl alcohol) and diisocyanates: binary blend of diisocyanates (1,6-hexamethylene diisocyanate (HDI) and 2,4-toluene diisocyanate (TDI)), isophorone diisocyanate (IPDI) or 4,4’-methylenebis(cyclohexyl isocyanate) (HMDI) were synthesized and studied in detail for first time. The influence of various reaction conditions such as: initial molar ratio of PVA and diisocyanate, synthesis time and temperature on the yield of PUU microparticles, quantity of functional groups, porosity and thermal stability was evaluated. PUU microparticles have crosslinked structure that contain hydroxyl groups, urethane linkages and poly(urea) chains of various lengths which could have the free isocyanate groups. PUU microparticles have plate-like shapes with slit-shaped pores. The immobilization of Ma onto PUU microparticles could proceed by covalent attachment and physical adsorption. Covalent immobilization of BsMa onto PUU microparticles could proceed via reactions of free isocyanate groups of PUU microparticles and amino or hydroxyl groups of enzyme, and urea or urethane linkages could be produced. Enzymatic activity, stability, optimal temperature, Michaelis-Menten constants and maximum reaction rates of native and immobilized Ma were particularly studied. Ma immobilized onto PUU microparticles obtained from PVA and IPDI under optimal conditions can be used for starch hydrolysis. These PUU microparticles were successfully used for immobilization of urease and biosensors design to determine concentration of urea, too. |
