Zj. Liu et al., A new tyrosinase biosensor based on tailoring the porosity of A1(2)O(3) sol-gel to co-immobilize tyrosinase and the mediator, ANALYT CHIM, 407(1-2), 2000, pp. 87-96
A new tyrosinase biosensor has been developed, based on the co-immobilizati
on of tyrosinase and the mediator, Fe(CN)(6)(4-), in positively charged Al2
O3 sol-gel membranes. Different sizes of molecules were entrapped into the
sol-gel membranes with different size pores, which were obtained by changin
g the ratio of Al : H2O during the sol-gel process. Tyrosinase was immobili
zed on a matrix with relatively large pores, Fe(CN)(6)(4-) was immobilized
on a matrix with smaller pores. The stability of the encapsulation molecule
s was further enhanced by the electrostatic interaction between the molecul
es and matrix. The enzyme immobilized in the porous and hydrophilic sol-gel
matrices is much stable and retains its functional activity to a large ext
ent. The accumulation of the o-quinones in the alumina film greatly improve
d the sensitivity of the sensor. The process parameters for the fabrication
of the enzyme biosensor were optimized. The detection limit is 5.0 x 10(-8
) mol/l, the Lifetime is more than 1 month. (C)2000 Elsevier Science B.V. A
ll rights reserved.