Biosensor for direct determination of organophosphate nerve agents. 1. Potentiometric enzyme electrode

A potentiometric enzyme electrode for the direct measurement of organophosphate (OP) nerve agents was developed. The basic element of this enzyme electrode was a pH electrode modified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linking OPH with bovine serum albumin (BS...

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Bibliographic Details
Published in:Biosensors & bioelectronics 1999, Vol.14 (1), p.77-85
Main Authors: Mulchandani, Priti, Mulchandani, Ashok, Kaneva, Irina, Chen, Wilfred
Format: Article
Language:English
Subjects:
Aldehydes
Animals
Aryldialkylphosphatase
Biological and medical sciences
Biosensing Techniques - statistics & numerical data
Biosensors
Biotechnology
Buffers
Catalysis
Cattle
Cross-Linking Reagents
Drug products
Electrodes
Enzyme electrode
Enzyme immobilization
Enzyme Stability
Esterases
Fundamental and applied biological sciences. Psychology
Glutaral
Hydrogen-Ion Concentration
Hydrolysis
Methods. Procedures. Technologies
Nerve agents
Nervous System - drug effects
Organophosphates
Organophosphorus Compounds - analysis
Organophosphorus Compounds - toxicity
Organophosphorus hydrolase
pH sensors
Phosphates
Potentiometric
Potentiometric sensors
Potentiometry
Serum Albumin, Bovine
Temperature
Thermal effects
Various methods and equipments
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Summary:A potentiometric enzyme electrode for the direct measurement of organophosphate (OP) nerve agents was developed. The basic element of this enzyme electrode was a pH electrode modified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linking OPH with bovine serum albumin (BSA) and glutaraldehyde. OPH catalyses the hydrolysis of organophosphorus pesticides to release protons, the concentration of which is proportional to the amount of hydrolysed substrate. The sensor signal and response time was optimized with respect to the buffer pH, ionic concentration of buffer, temperature, and units of OPH immobilized using paraoxon as substrate. The best sensitivity and response time were obtained using a sensor constructed with 500 IU of OPH and operating in pH 8.5, 1 mM HEPES buffer. Using these conditions, the biosensor was used to measure as low as 2 μM of paraoxon, ethyl parathion, methyl parathion and diazinon. The biosensor was completely stable for at least one month when stored in pH 8.5, 1 mM HEPES +100 mM NaCl buffer at 4°C.
ISSN:0956-5663
1873-4235
DOI:10.1016/S0956-5663(98)00096-7