Poly( p-maleimidostyrene) coated cross-linked polystyrene beads as novel ultrasonic irradiation resistant enzyme immobilization materials−Applications for biosensors and bioreactors

Abstract

Poly( p-maleimidostyrene) (PMS) was coated on cross-linked polystyrene(CLPS) beads. Enzymes (i.e., urease and fumarase) were stably immobilized on the beads via simple immersion into an enzyme solution for 30 min. Characterizations of PMS-coated on CLPS beads and evaluations of the enzymatic activity of bead-immobilized enzymes were conducted with confocal laser microscopy, electrochemical analysis, and spectrophotometry. Immobilized urease and fumarase demonstrated satisfactory enzyme activities. The K m of immobilized urease was estimated using electrochemical measurements and was found to be 2.2 × 10 −3 M at 20 °C. PMS coating and immobilized enzymes both did not detach from the CLPS bead surface, even after ultrasonic irradiation. A biosensor using urease-immobilized PMS-coated CLPS beads showed good performance as a urea sensor. Furthermore, fumarase-immobilized PMS-coated beads may be promising materials for bioreactors producing ( S)-(−)-malic acid.