Optical-fiber Biosensor For Determining Nerve Organophosphorus Agents And Pesticides

In part one, an optical-fiber biosensor based on acetylcholinesterase (AChE) for detection of nerve organophosphorus agents and pesticides has been fabricated by using N-fluoresceinacrylamide synthesized in this laboratory as the fluorescent agent. The protons produced in the process of acetylcholine bromide hydrolysis quenched the pH-dependent fluorescent signal generated by N-fluoresceinacrylamide-AchE. The inhibitor, such as Soman, Sarin, Vx, 613, GF, Dichlorvos (DDVP) and Diethyl p-nitrophenyl phosphate (Paraoxon) inhibited AchE and consequently reduced fluorescence quenching. Parathion and methyl-parathion have no response to the optode even at millimolar concentrations. The optode membrane can be reactivated with praloxime chloride (2-PAM-Cl) solution. The analytical performance including reversibility, reproducibility, stability and selectivity have been evaluated, and can be applied for the direct determination in water samples with satisfactory recoveries.In part two, sol-gel based fiber-optic biosensor with acetylcholinesterase(AchE) as the biorecognition element has been development for the determination of nerve organophosphorus agents and pesticides. The experimental result showed that 5-fluorescein isothiocyanate (FITC) was sensitive to the change of pH value caused by the enzyme-substrate catalysis reaction. The reversible inhibitor, such as Sarin, Vx and Diethyl p-nitrophenyl phosphate (Paraoxon) inhibited AchE and consequently reducedfluorescence quenching. The biosensor response immediately recovered upon their removal and can be reactivated with praloxime chloride (2-PAM-Cl) solution. However, Soman can inhibit the biosensor response but not reactivated with pralidoxime (2-PAM-Cl). The analytical performance including reversibility, reproducibility, stability and selectivity have been evaluated, and can be applied for the direct determination in water samples with satisfactory recoveries.