Phospholipid-coated electrodes for the electrochemical detection of phospholipase A2
Phospholipid-coated electrodes for the electrochemical detection of phospholipase A2
Supported-phospholipid films have many potential applications as biosensors, such as the detection of phospholipase A2. Phospholipid films were prepared by spontaneous fusion of phospholipid vesicles with a hydrophobic alkanethiol self-assembled monolayer on gold. The deposition and final state of the phospholipid-coated electrodes were characterised using electrochemical impedance spectroscopy, the quartz crystal microbalance, atomic force microscopy, cyclic voltammetry and ellipsometry. Only by combining results gained with each of these techniques could a reliable description of the phospholipid-coated electrodes be achieved. The alkanethiol layer was of unimolecualr thickness with 97-99% coverage and contained some defects. The phospholipid layer was a well-defined laminar film of trilayer thickness. In electrolyte, the deposition of the phospholipid film occurred in two stages attributed to a monolayer of phospholipid followed by a further bilayer.
Based on this description of the phospholipid-coated electrodes, an electrochemical impedance equivalent circuit was derived and found to give excellent fits to the experimental data. Phospholipase A2 hydrolyses phospholipid molecules in phospholipid aggregates. This enzyme reaction was detected by monitoring the impedance changes, using electrochemical impedance spectroscopy, and by measuring the redox chemistry of a probe series, using cyclic voltammetry. These electrochemical changes depended on enzyme concentration, temperature, coenzyme, phospholipid type and potential. Impedance changes could be analysed quantitatively and were consistent with the accepted kinetics of phospholipase A2 at phospholipid membranes. In conclusion, phospholipid-coated alkanethiol monolayers are a useful analogue for a phospholipid membrane with the stability, reproducibility and sensitivity necessary for phospholipase A2 detection.
University of Southampton
1999
Brace, Karen Marie
(1999)
Phospholipid-coated electrodes for the electrochemical detection of phospholipase A2.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Supported-phospholipid films have many potential applications as biosensors, such as the detection of phospholipase A2. Phospholipid films were prepared by spontaneous fusion of phospholipid vesicles with a hydrophobic alkanethiol self-assembled monolayer on gold. The deposition and final state of the phospholipid-coated electrodes were characterised using electrochemical impedance spectroscopy, the quartz crystal microbalance, atomic force microscopy, cyclic voltammetry and ellipsometry. Only by combining results gained with each of these techniques could a reliable description of the phospholipid-coated electrodes be achieved. The alkanethiol layer was of unimolecualr thickness with 97-99% coverage and contained some defects. The phospholipid layer was a well-defined laminar film of trilayer thickness. In electrolyte, the deposition of the phospholipid film occurred in two stages attributed to a monolayer of phospholipid followed by a further bilayer.
Based on this description of the phospholipid-coated electrodes, an electrochemical impedance equivalent circuit was derived and found to give excellent fits to the experimental data. Phospholipase A2 hydrolyses phospholipid molecules in phospholipid aggregates. This enzyme reaction was detected by monitoring the impedance changes, using electrochemical impedance spectroscopy, and by measuring the redox chemistry of a probe series, using cyclic voltammetry. These electrochemical changes depended on enzyme concentration, temperature, coenzyme, phospholipid type and potential. Impedance changes could be analysed quantitatively and were consistent with the accepted kinetics of phospholipase A2 at phospholipid membranes. In conclusion, phospholipid-coated alkanethiol monolayers are a useful analogue for a phospholipid membrane with the stability, reproducibility and sensitivity necessary for phospholipase A2 detection.
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Published date: 1999
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Local EPrints ID: 464081
URI: http://eprints.soton.ac.uk/id/eprint/464081
PURE UUID: d42fdcf5-0cf9-461f-b513-214cad6cc167
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Date deposited: 04 Jul 2022 21:02
Last modified: 04 Jul 2022 21:02
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Author:
Karen Marie Brace
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