Oxygen tolerance of an implantable polymer/enzyme composite glutamate biosensor displaying polycation-enhanced substrate sensitivity

McMahon, Colm P.; Rocchitta, Gaia; Kirwan, Sarah M.; Killoran, Sarah J.; Serra, Pier Andrea; Lowry, John; O’Neill, Robert

doi:10.1016/j.bios.2006.06.027

Cited by 68 publications

(67 citation statements)

References 67 publications

(92 reference statements)

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“…PPD modified Pt electrodes are extensively utilised to improve selectivity of the polymer layer of both electrochemical sensors [6,17,[22][23][24] and biosensors [11,[25][26][27][28] since extracellular concentrations of certain metabolites are considered low in relation to the excessive concentration of AA. Therefore it is imperative that the integrity of the polymer is retained following implantation.…”

Section: Shelf-life Studies-effect Of Repeated Aa Calibrationsmentioning

confidence: 99%

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Ascorbic Acid Rejection Characteristics of Modified Platinum Electrodes: A Shelf Life Investigation

Wynne

Finnerty

2015

Chemosensors

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Ascorbic acid (AA) is the principle interferent present in brain extracellular fluid that can inhibit the ability of electrochemical sensors to selectively detect a particular analyte of interest. Considerable efforts have been made in recent times to develop highly selective membrane coatings to counteract the drawbacks associated with AA interference during in vivo monitoring. The primary objective of the work described within was to investigate the long term effect of storing such selective membranes, i.e., Nafion ® andPoly-o-phenylenediamine (PPD) under different conditions and how exposing them to repeated calibration protocols compromises the membranes ability to reject AA. Four different modified platinum (Pt) electrodes, Pt-PPD, Pt-Nafion ® (5/2), Pt-Nafion ® (1/2)-PPD, and Pt-Nafion ® (2/1)-PPD, stored at 4 °C demonstrated deterioration of the polymers integrity when exposed to repeated calibrations. On the contrary, exposing the same four electrode types to single calibrations confirmed excellent retention of AA rejection characteristics. Pt-PPD electrodes were then exposed to varying storage conditions and calibrated against AA on day 1, day 56 and day 168. Storing the Pt-PPD electrodes at 4 °C/N2 saturated glass container demonstrated retention of AA rejection characteristics after day 168. These results have clearly elucidated the optimum storage conditions for Pt-Nafion ® and Pt-PPD modified electrodes.

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Section: Shelf-life Studies-effect Of Repeated Aa Calibrationsmentioning

confidence: 99%

“…Poly-o-phenylenediamine (PPD) can be integrated into the design of electrochemical sensors to function either as a conducting polymer [9] or more commonly as an insulating polymer [10,11]. Electropolymerisation of the monomer o-phenylenediamine (o-PD) in pH 7.4, deposits PPD in its insulating form onto the electrode surface [12].…”

Section: Introductionmentioning

confidence: 99%

Ascorbic Acid Rejection Characteristics of Modified Platinum Electrodes: A Shelf Life Investigation

Wynne

Finnerty

2015

Chemosensors

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“…Despite having multiple layers, the response time of this configuration was found to be good at ∼5 s. The Michaelis-Menten constants of J max and K M for the configuration were found to be 77 A cm −2 and 873 M (R 2 = 0.99, n = 21), respectively. The limit of detection (based on 3× SD of the baseline current) of this configuration was calculated to be ∼2.5 M glutamate, which is lower [ 47], who demonstrated that PPD-coated electrodes were highly efficient even at low oxygen concentrations, such as during ischaemia.…”

Section: Pt D /Ppd-bsa/pea/pei/gluox/ppd-bsamentioning

confidence: 99%

Highly selective and stable microdisc biosensors for l-glutamate monitoring

Govindarajan

McNeil

Lowry

et al. 2013

Sensors and Actuators B: Chemical

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a b s t r a c tGlutamate mediates most of the excitatory synaptic transmission in the brain, and its abnormal regulation is considered a key factor underlying the appearance and progression of many neurodegenerative and psychiatric diseases. In this work, a microdisc-based amperometric biosensor for glutamate detection with highly enhanced selectivity and good stability is proposed. The biosensor utilizes the enzyme glutamate oxidase which was dip-coated onto 125 m diameter platinum discs. To improve selectivity, phosphatidylethanolamine was pre-coated prior to enzyme deposition, and electropolymerization of o-phenylenediamine was performed to entrap the enzyme within a polymer matrix. A variety of coating configurations were tested in order to optimize biosensor performance. For stability measurements, biosensors were biased continuously and calibration curves calculated each day for a period of 5-6 days. The optimized biosensors exhibited very high sensitivity (71 ± 1 mA M −1 cm −2 ), low detection limit of ∼2.5 M glutamate, selectivity (over 87% against ascorbic acid), very good temporal stability during continuous use, and a response time of <5 s. These biosensors are therefore good candidates for further development as devices for continuous monitoring during traumatic brain injury or neurosurgery.

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“…Using implantable sensors allows for stable, long-term recording of a number of common analytes in the extracellular fluid (ECF) of the brain including oxygen (Lowry et al, 1996Lowry and Fillenz, 2001;Bolger and Lowry, 2005), glucose (Hu and Wilson, 1997;Fillenz and Lowry, 1998a;Lowry et al, 1998a,b,c;Lowry and Fillenz, 2001;Dixon et al, 2002), nitric oxide (Brown et al, 2009) and glutamate (Kulagina et al, 1999;McMahon et al, 2006aMcMahon et al, , 2006bMcMahon et al, , 2007Qin et al, 2008;Tian et al, 2009). Unlike other methods implanted into the brain tissue (Clark et al, 1958;Krolicki and Leniger-Follert, 1980;Doppenberg et al, 1998;Gupta et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous recording of hippocampal oxygen and glucose in real time using constant potential amperometry in the freely-moving rat

Kealy

Bennett

Lowry

2013

Journal of Neuroscience Methods

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h i g h l i g h t sWe show that average concentrations of hippocampal oxygen and glucose are 100.26 ± 5.76 M and 0.60 ± 0.06 mM respectively. We show that there are uncoupled changes in oxygen and glucose during neuronal activation. Anaesthesia and carbonic anhydrase inhibition both significantly increase hippocampal oxygen. Anaesthesia, dimethyl sulfoxide administration and carbonic anhydrase inhibition significantly increase hippocampal glucose. We show that changes in hippocampal metabolism can be detected in real time using constant potential amperometry. a r t i c l e i n f o t r a c tAmperometric sensors for oxygen and glucose allow for real time recording from the brain in freelymoving animals. These sensors have been used to detect activity-and drug-induced changes in metabolism in a number of brain regions but little attention has been given over to the hippocampus despite its importance in cognition and disease. Sensors for oxygen and glucose were co-implanted into the hippocampus and allowed to record for several days. Baseline recordings show that basal concentrations of hippocampal oxygen and glucose are 100.26 ± 5.76 M and 0.60 ± 0.06 mM respectively. Furthermore, stress-induced changes in neural activity have been shown to significantly alter concentrations of both analytes in the hippocampus. Administration of O 2 gas to the animals' snouts results in significant increases in hippocampal oxygen and glucose and administration of N 2 gas results in a significant decrease in hippocampal oxygen. Chloral hydrate-induced anaesthesia causes a significant increase in hippocampal oxygen whereas treatment with the carbonic anhydrase inhibitor acetazolamide significantly increases hippocampal oxygen and glucose. These findings provide real time electrochemical data for the hippocampus which has been previously impossible with traditional methods such as microdialysis or ex vivo analysis. As such, these sensors provide a window into hippocampal function which can be used in conjunction with behavioural and pharmacological interventions to further elucidate the functions and mechanisms of action of the hippocampus in normal and disease states.

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Oxygen tolerance of an implantable polymer/enzyme composite glutamate biosensor displaying polycation-enhanced substrate sensitivity

Cited by 68 publications

References 67 publications

Ascorbic Acid Rejection Characteristics of Modified Platinum Electrodes: A Shelf Life Investigation

Ascorbic Acid Rejection Characteristics of Modified Platinum Electrodes: A Shelf Life Investigation

Highly selective and stable microdisc biosensors for l-glutamate monitoring

Simultaneous recording of hippocampal oxygen and glucose in real time using constant potential amperometry in the freely-moving rat

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