Characterisation of a Platinum‐based Electrochemical Biosensor for Real‐time Neurochemical Analysis of Choline

Baker, Keeley L.; Bolger, Fiachra B.; Doran, Michelle M.; Lowry, John

doi:10.1002/elan.201800642

Cited by 16 publications

(12 citation statements)

References 51 publications

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“…Based on the presented results, it can be summarized that the newly developed amperometric biosensor with ChOx‐SBA15 reactor possesses good sensitivity, repeatability and high reproducibility for Ch detection. Despite the lower LOD for determination of Ch in comparison with previously published papers with biosensors of classic construction (lower LOD than in ), our biosensor based on the enzymatic reactor ChOx‐SBA15 exhibits higher stability and reusability. Compared to the Ch biosensor with enzymatic reactor previously proposed , the developed biosensor with ChOx‐SBA15 reactor exhibits the similar sensitivity.…”

Section: Resultsmentioning

confidence: 99%

Amperometric Biosensor Based on Enzymatic Reactor for Choline Determination in Flow Systems

2019

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A simple, selective and stable biosensor with the enzymatic reactor based on choline oxidase (ChOx) was developed and applied for the determination of choline (Ch) in flow injection analysis with amperometric detection. The enzyme ChOx was covalently immobilized with glutaraldehyde to mesoporous silica powder (SBA‐15) previously covered by NH2‐groups. This powder was found as an optimal filling of the reactor. The detection of Ch is based on amperometric monitoring of consumed oxygen during the enzymatic reaction, which is directly proportional to Ch concentration. Two arrangements of an electrolytic cell in FIA, namely wall‐jet cell with working silver solid amalgam electrode covered by mercury film and flow‐through cell with tubular detector of polished silver solid amalgam were compared. The experimental parameters affecting the sensitivity and stability of the biosensor (i. e. pH of the carrier solution, volume of reactor, amount of the immobilized enzyme, the detection potential, flow rate, etc.) were optimized. Under the optimized conditions, the limit of detection was found to be 9.0×10−6 mol L−1. The Michaelis‐Menten constant for covalently immobilized ChOx on SBA‐15 was calculated. The proposed amperometric biosensor with the developed ChOx‐based reactor exhibits good repeatability, reproducibility, long‐term stability, and reusability. Its efficiency has been confirmed by the successful application for the determination of Ch in two commercial pharmaceuticals.

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Section: Resultsmentioning

confidence: 99%

Amperometric Biosensor Based on Enzymatic Reactor for Choline Determination in Flow Systems

2019

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“…Changes in extracellular choline were monitored in freely-moving mice using constant potential amperometry (CPA) with choline microelectrochemical biosensors (Baker et al ., 2015; Teles-Grilo Ruivo et al ., 2017; Baker et al ., 2018). In brief, biosensors were constructed from Teflon ® -coated, Pt/Ir (90%/10%) wire (75µm bare diameter, 112 µm coated diameter; Advent Research Materials).…”

Section: Methodsmentioning

confidence: 99%

“…A fresh disk was cut at the opposite end, which acted as the active surface. The disk surface was coated with a layer of electropolymerized poly- o -phenylenediamine (PPD; >98%), a well characterised interference rejection layer making the sensor highly selective for choline (Lowry et al ., 1998; Baker et al ., 2015; Baker et al ., 2018). The PPD-modified electrode was initially dipped in methylmethacrylate (MMA; 99%) and cellulose acetate solutions, and then sequentially dipped into choline oxidase (ChOx; from Alcaligenes sp., EC 232-840-0), bovine serum albumin (BSA; fraction V from bovine plasma), glutaraldehyde (Grade 1, 25%) and polyethyleneimine (PEI; 80% ethoxylated) using a dip absorption method.…”

Section: Methodsmentioning

confidence: 99%

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Cholinergic signalling in the forebrain controls microglial phenotype and responses to systemic inflammation

Nazmi

Griffin

Field

et al. 2021

Preprint

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Abstract(250)Loss of basal forebrain cholinergic projections occurs in Alzheimer’s disease, frontotemporal dementia and in aging. Moreover, nicotinic stimulation is anti-inflammatory in macrophages and microglia but how loss of basal forebrain acetylcholine impacts on microglial phenotype is poorly understood. Here we hypothesized that endogenous ACh maintains homeostatic microglial phenotype and that neurodegeneration-evoked loss of ACh tone, triggers microglial activation. Using the specific immunotoxin, mu-p75NTR-saporin, we performed partial lesions of the basal forebrain cholinergic nuclei, medial septum and ventral diagonal band. We examined microglial phenotype in the hippocampus, the major projection area for these nuclei, using bulk RNA preparations, Flow cytometry-sorted microglial cells, immunohistochemistry and ELISA to examine responses to cholinergic withdrawal and acute responses to subsequent systemic inflammation with LPS. Basal forebrain cholinergic degeneration elicited lasting activation of microglia in the hippocampus, showing suppression of Sall1 and persistent elevation of Trem2, Clec7a, Itgax and complement genes proportionate to Chat loss. These primed microglia showed exaggerated IL-1β responses to systemic LPS challenge. In normal animals LPS evoked acute increases in extracellular choline, a proxy for ACh release, and this response was lost in lesioned animals. Restoration of basal cholinergic signalling via serial treatments with the nicotinic agonist PNU282,987 resulted in reversion to the homeostatic microglial phenotype and prevented exaggerated responses to acute systemic inflammation. The data indicate that neurodegeneration-evoked loss of cholinergic tone, triggers microglial activation via impaired microglial nicotinic signalling and leaves these microglia more vulnerable to secondary inflammatory insults. The data have implications for neuroinflammation during aging and neurodegeneration and for responses to sepsis and systemic inflammation.

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“…Platinum (Pt) is perhaps the most widely used electrode material for H 2 O 2 detection at microelectrodes, particularly when incorporated into electro-enzymatic biosensors. While early versions of such sensors utilized platinum wires [5], we and others [6] have fabricated oxidase-based microscale Pt-based microelectrode array (MEA) biosensors for selective and near-real-time detection of glutamate and choline in brain to study the neuronal processes underlying complex behaviors.…”

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confidence: 99%

Pt Nanoparticle‐modified Carbon Fiber Microelectrode for Selective Electrochemical Sensing of Hydrogen Peroxide

et al. 2019

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We report a simple approach to the production of carbon fiber‐based amperometric microbiosensors for selective detection of hydrogen peroxide (H2O2), which was achieved by electrometallization of carbon fiber microelectrodes (CFMs) by electrodeposition of Pt nanoparticles. The Pt‐carbon hybrid sensing interface provided a sensitivity of 7711±587 μA ⋅ mM−1 ⋅ cm−2, a detection limit of 0.53±0.16 μM (S/N=3), a linear range of 0.8 μM–8.6 mM, and a response time of <2 sec. The morphologies of the Pt nanoparticle‐modified CFMs were characterized by scanning electron microscopy. To achieve selectivity, permseletive layers, polyphenylenediamine (PPD) and Nafion, were deposited resulting in exclusion of the anionic and cationic interferents, ascorbic acid and dopamine, respectively, at their physiologically relevant concentrations. The resultant sensors displayed a sensitivity to hydrogen peroxide of 1381±72 μA ⋅ mM−1 ⋅ cm−2, and a detection limit of 0.86±0.19 μM (S/N=3). This simple and rapid metallization method converts carbon fiber microelectrodes, which are readily accessible, to microscale Pt electrodes in 2 min, providing a platform for oxidase‐based amperometric biosensors with improved spatial resolution over more commonly used platinum electrode array microprobes.

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Characterisation of a Platinum‐based Electrochemical Biosensor for Real‐time Neurochemical Analysis of Choline

Cited by 16 publications

References 51 publications

Amperometric Biosensor Based on Enzymatic Reactor for Choline Determination in Flow Systems

Amperometric Biosensor Based on Enzymatic Reactor for Choline Determination in Flow Systems

Cholinergic signalling in the forebrain controls microglial phenotype and responses to systemic inflammation

Pt Nanoparticle‐modified Carbon Fiber Microelectrode for Selective Electrochemical Sensing of Hydrogen Peroxide

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