Utilização de diferentes tipos de imobilização da enzima oxalato oxidase na construção de biossensores

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

This work is based on development of potentiometric and amperometric biosensors in order to analyse oxalate. Several technics of enzyme immobilization were used to immobilize oxalate oxidase on beet stem which were used as enzyme suport and submitted to differents kinds of immobilization ( gamma radiation, covalent linkage, adsortion and natural) making potentiometric biosensor. The purified enzyme was immobilizated by oclusion in the carbon paste to obtain an amperometric biosensor. An enzyme reactor with amperometric detection was made using spiny pigweed as enzyme source. The immobilization by gamma irradiation gave more enzyme lifetime and when it is associated with glutaraldehyde provided more stability to immobilization process. Probably, the gamma irradiation helps in the process of covalent linkage formation, making then more effective. The oxigen ambient inhibits the formation of these linkages while in the presence of buffer, the enzyme activity is inhibited. The amperometric biosensors, showed usefull working range of 1x10 - 1x10 mol/L for oxalic acid, which are easy to prepare and to handle. The use of mediators could be efficient to eliminate electroactives interferences which is detectable in higher potentials. By studies performed with a enzyme reactor acopled to a FIA system, the Km value for the natural spiny pigweed enzyme was found to be 1,3x 10 mol/L and the usefull range for oxalic acid determination was 2,5x10 - 1,0x10 mol/L.

ASSUNTO(S)

biossensores cromatografia de troca ionica colorimetria calorimetria enzimas imobilizadas

ACESSO AO ARTIGO

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