Abstract
Ethyl alcohol may be considered one of the most widespread central nervous system (CNS) depressants in Western countries. Because of its toxicological and neurobiological implications, the detection of ethanol in brain extracellular fluid (ECF) is of great importance. In a previous study, we described the development and characterization of an implantable biosensor successfully used for the real-time detection of ethanol in the brain of freely-moving rats. The implanted biosensor, integrated in a low-cost telemetry system, was demonstrated to be a reliable device for the short-time monitoring of exogenous ethanol in brain ECF. In this paper we describe a further in-vitro characterization of the above-mentioned biosensor in terms of oxygen, pH and temperature dependence in order to complete its validation. With the aim of enhancing ethanol biosensor performance, different enzyme loadings were investigated in terms of apparent ethanol Michaelis-Menten kinetic parameters, viz. IMAX, KM and linear region slope, as well as ascorbic acid interference shielding. The responses of biosensors were studied over a period of 28 days. The overall findings of the present study confirm the original biosensor configuration to be the best of those investigated for in-vivo applications up to one week after implantation.
Highlights
Ethanol is a ubiquitous psychoactive agent in Western society
In this study we investigated the response of alcohol biosensors at a fixed ethanol concentration of about 15 mM, a value found in vivo after a single intragastric administration of 1 g·kg−1 of ethanol [5], as well as the biosensor response to varying the oxygen concentration in the electrochemical cell
In order to enhance ethanol biosensor performance, different enzyme loadings were investigated in terms of apparent ethanol Michaelis-Menten kinetic parameters, IMAX and KM, the linear region slope (LRS) and enzyme oxygen dependence
Summary
Its effects are mainly associated with the modulation of GABAergic and glutamatergic systems; the positive reinforcing properties of ethanol are related to activation of dopaminergic pathways, producing dopamine release in the nucleus accumbens. In view of these neurobiological aspects, the detection of ethanol in brain extracellular fluid (ECF) is of great importance. Several studies in the literature have reported ethanol pharmacokinetics and concentrations in the brain after systemic injection, and showed that ethanol in the CNS could reach concentrations of about 30 mM [1,2,3,4] AOx is capable of catalyzing the oxidation of primary, aliphatic short-chain alcohols (such as ethanol and methanol) to their respective aldehydes as follows: RCH2OH + AOx/FAD → RCHO + AOx/FADH2
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