Desenvolvimento e avaliação de um biossensor amperometrico a base de peroxidase para determinação de neurotransmissores

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Neurotransmitters are compounds that have a very important role on human body and their analysis have an especial interest to medical and pharmacological areas. This type of analysis using a biosensor with HRP enzyme immobilized on carbon paste might be an interesting alternative to the traditional methods that are low selective (fluorimetric), very expensive (GC-MS), or takes much time to accomplish the results (HPLC-ED). The characteristics mentioned above make them non appropriate for quick analysis. Thus, this work describes the biosensor development and its use for determination of neurotransmitter in biological samples. Eight different protocols on the HRP enzyme immobilization were used and optimal experimental conditions were determined using a serotonin solution as a standard. Values of sensitivity were evaluated by adding glutaraldehyde, bovine serum albumin, and carbodiimide to the enzyme immobilization processo The results showed that the paste composition has great influence on the enzyme activity for serotonin oxidation. The best results were obtained in 0.1 moI L-I phosphate buffer (pH=7.0) containing 10 J..lmol L-I of hydrogen peroxide at an applied potential of -50 mV vs SCE. On these conditions, the biosensor showed a linear response range from 0.2 to 2.0 J..lIDol L-I, a detection limit ofO.08 J..lIDol L-I and the response time was 0.5 seconds. The biosensor sensitivities for dopamine, epinephrine and norepinephrine were practically the same. For serotonin, the biosensor showed a slight lower sensitivity, what agrees with its redox potential. The proposed biosensor presented a stable response during 4 h under continuous monitoring. The difference of response was of 2% among six different preparations. The biosensor showed a successful use on the determination of the total ftaction of neurotransmitters in rat blood samples, obtaining an average recovery of 102%

ASSUNTO(S)

serotonina biossensores neurorreguladores

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