ИСТИНА

Some of OPs were found to induce a delayed neuropathy (OPIDN). A specific target for OPIDN initiation is neuronal protein known as Neuropathy Target Esterase (neurotoxic esterase, NTE). The correlation occurs between the ability of OP to inhibit NTE activity and to induce OPIDN. A biosensor for the NTE activity measurements was constructed based on Clark-type oxygen electrode modified by immobilized tyrosinase. The analytical signal of amperometric biosensor (oxygen consumption detected by Clark electrode) is proportional to the quantity of phenol. The latter is the product of enzymatic hydrolysis of phenyl valerate by NTE. At the same time phenol is the sunstrate for the enzymatic oxidation to catechol and finally to 1,2-benzoquinone by tyrosinase proceeding with oxygen consumption. The experiments were carried out for realizing a chemically amplified signal by combining the tyrosinase reaction and a reducing agent (L-ascorbic acid) in order to decrease the level of tyrosinase-based biosensor sensitivity. The analytical response of biosensor is linear in the range of phenol concentration from 5E-08 M to 1E-06 M. Minimum concentration of NTE that can be determined in standard conditions by this biosensor is approximately 2E-09 M. It is expected that this sensitive, simple and low-cost biosensor's method can be used either for the environmental monitoring of organophosphorus delayed neurotoxicants and for early clinical diagnostics of OPIDN.