A solid contact biosensor for Acetylcholine (ACh) based on host-guest interactions and potentiometric transduction has been designed and
characterized. The biomimetic man-tailored host was synthesized using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker in the presence of benzoyl peroxide as an initiator. The imprinted beads were dispersed in 2-nitrophenyloctyl
ether and entrapped in a poly(vinyl chloride) matrix. Slopes and detection limits are 55.2-59.6 mV decade-1
and 0.65-1.31 μg mL-1
,
respectively. Significantly, improved accuracy, precision, good reproducibility, long-term stability, selectivity and sensitivity were offered
by these simple and cost-effective potentiometric biosensors. A tubular version was further developed and coupled to a flow injection system
for acetylcholine determination. This simple and inexpensive flow injection analysis manifold, with a good potentiometric detector, enabled
the analysis of ∼30 samples h-1 without requiring pretreatment procedures. An average recovery of 98.3 % and a mean standard deviation of
1.1% were obtained. The sensors were used to follow up the decrease of a fixed concentration of ACh+
substrate as a function of
acetylcholinesterase (AChE) activity under optimized conditions of pH and temperature. A linear relationship between the hydrolysis initial
rate of ACh+
substrate and enzyme activity hold 0.01- 5.0 IU L-1 of AChE enzyme.
Key words: Acetylcholine, acetylcholinesterase enzyme assay, molecular imprinted polymers, potentiometry, flow injection analysis
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