Critical Evaluation of Acetylthiocholine Iodide and Acetylthiocholine Chloride as Substrates for Amperometric Biosensors Based on Acetylcholinesterase
نویسندگان
چکیده
Numerous amperometric biosensors have been developed for the fast analysis of neurotoxic insecticides based on inhibition of cholinesterase (AChE). The analytical signal is quantified by the oxidation of the thiocholine that is produced enzymatically by the hydrolysis of the acetylthiocholine pseudosubstrate. The pseudosubstrate is a cation and it is associated with chloride or iodide as corresponding anion to form a salt. The iodide salt is cheaper, but it is electrochemically active and consequently more difficult to use in electrochemical analytical devices. We investigate the possibility of using acetylthiocholine iodide as pseudosubstrate for amperometric detection. Our investigation demonstrates that operational conditions for any amperometric biosensor that use acetylthiocholine iodide must be thoroughly optimized to avoid false analytical signals or a reduced sensitivity. The working overpotential determined for different screen-printed electrodes was: carbon-nanotubes (360 mV), platinum (560 mV), gold (370 mV, based on a catalytic effect of iodide) or cobalt phthalocyanine (110 mV, but with a significant reduced sensitivity in the presence of iodide anions).
منابع مشابه
Acetylcholinesterase Inhibition-Based Biosensor for Aluminum(III) Chronoamperometric Determination in Aqueous Media
A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme acetylcholinesterase has been developed. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles. The oxidation signal of acetylthiocholine iodide enzyme substrate was affected by the presence of Al(III) ions leading to a decrease in t...
متن کاملA sensitive amperometric acetylcholine biosensor based on carbon nanosphere and acetylcholinesterase modified electrode for detection of pesticide residues.
A sensitive biosensor based on acetylcholinesterase (AChE) and carbon nanosphere (CNS) immobilized on a glassy carbon electrode was developed for the detection of pesticides by the inhibition of AChE activity. The inhibition effect of the pesticides resulted in a decrease of current response of the acetylthiocholine chloride that was used as a substrate to obtain an electrochemical signal. When...
متن کاملMediated enzyme screen-printed electrode probes for clinical, environmental and food analysis
Since the appearance of the first amperometric biosensors based on the coupling of oxidase enzymes and relying on the final detection of H2O2, it was clear that one of the major problems related to this kind of configuration was due to the high overpotential needed for H2O2 oxidation (ca. 0.7V vs. Ag/AgCl). At this potential in fact, many electroactive substances (i.e. ascorbic acid, uric acid ...
متن کاملA New Assay for Measurement of Acetylcholinesterase and Butyrylcholinesterase in Canine Whole Blood Combining Specific Substrates and Ethopropazine Hydrochloride as a Selective Butyrylcholinesterase Inhibitor
Received: Revised: Accepted: April 13, 2013 April 17, 2013 April 24, 2013 In the present report, a new assay combining specific substrates and a selective BChE inhibitor (ethopropazine hydrochloride) was used to measure both AChE and BChE in canine whole blood samples. Acetylthiocholine iodide (ATCI) and butyrylthiocholine iodide (BTCI) were used as substrates, whereas 2,2’dithiodipiridine was ...
متن کاملA novel acetylcholine bioensor and its electrochemical behavior.
A novel type of acetylcholine electrochemical biosensor was successfully fabricated by dropping beta-cyclodextrin solution, acetylcholinesterase solution and Nafion-methanol solution to the homemade nano-porous pseudo carbon paste electrode (nano-PPCPE) as working electrode, and then the electrochemical behavior of the as-prepared biosensor was studied through the acetylthiocholine iodide (ATCh...
متن کامل