Impedance Analysis and Mathematical Modelling of Immunosensor Biolayer

Hdl Handle:
http://hdl.handle.net/10149/333365
Title:
Impedance Analysis and Mathematical Modelling of Immunosensor Biolayer
Authors:
Henderson, A. P. (Andrew)
Advisors:
Ali, Z. (Zulfiqur); Russell, P. A. (Paul)
Publisher:
My Institution
Issue Date:
2011
URI:
http://hdl.handle.net/10149/333365
Abstract:
A study to optimise an IgG based immunosensor is presented, that has been carried out by absorbing monolayers to a gold transducer surface at varying immersion times and temperatures. The theory and kinetics of monolayer adsorption are analysed and discussed. Existing mathematical models are reviewed and experimentally researched, to highlight gaps in knowledge that would facilitate high quality, cost effective immunosensor production. The creation of two mathematical models to predict monolayer adsorption kinetics and optimal immersion times are discussed. Details are provided of how the new mathematical models may be advanced, and how the production of immunosensors may be further improved. The first novel mathematical model (PTCS) has been created to model the presence of two sequentially forming structures on the surface of a substrate. It gives an insight into the percentages of each structure on the surface, along with the actual adsorption process. This model provides a good fit to all applicable experimental data and has allowed the deduction of optimum immersion times. The second novel model (PIF) provides a greater insight than existing models into the individual contributions to surface coverage by both random and island growth. This allows an insight into how the monolayer surface is covered, which is critical to determine the optimum conditions for adsorption. This model also provides a good fit to the isotherm data it has been applied to. To provide a thorough understanding of the bulk properties of monolayer formation over the gold transducer, and how these properties vary with immersion time and temperature, various measurement techniques have been employed. Electrochemical Impedance Spectroscopy (EIS) has been the principle measurement technique used to measure the bulk properties, but confirmation studies have also been carried out including, Contact angle measurements, FTIR microscopy with BSA molecular labels, Fluorescence microscopy for small adsorbed molecules and AFM for layers assembled from macromolecules. The data generated from the different techniques show consistency with the arguments discussed in each instance. Two different IgG adsorption processes have been compared. These include direct IgG addition and a multilayered streptavidin-based process. The results indicate that IgG molecules adsorbed via the streptavidin based multilayer process are more vertically orientated and have a higher packing density of IgG molecules. Keywords: Self Assembled Monolayer, impedance-based immunoassay, Streptavidin, biotinylated IgG, mathematical adsorption modelling.
Type:
Thesis or dissertation
Language:
en
Keywords:
adsorption; equations; self assembled monolayer; EDC and NHS crosslinkers; streptavidin
Sponsors:
EPSRC and Immunodiagnostic Systems (IDS) Ltd

Full metadata record

DC FieldValue Language
dc.contributor.advisorAli, Z. (Zulfiqur)en
dc.contributor.advisorRussell, P. A. (Paul)en
dc.contributor.authorHenderson, A. P. (Andrew)en
dc.date.accessioned2014-10-28T11:17:49Zen
dc.date.available2014-10-28T11:17:49Zen
dc.date.issued2011en
dc.identifier.urihttp://hdl.handle.net/10149/333365en
dc.description.abstractA study to optimise an IgG based immunosensor is presented, that has been carried out by absorbing monolayers to a gold transducer surface at varying immersion times and temperatures. The theory and kinetics of monolayer adsorption are analysed and discussed. Existing mathematical models are reviewed and experimentally researched, to highlight gaps in knowledge that would facilitate high quality, cost effective immunosensor production. The creation of two mathematical models to predict monolayer adsorption kinetics and optimal immersion times are discussed. Details are provided of how the new mathematical models may be advanced, and how the production of immunosensors may be further improved. The first novel mathematical model (PTCS) has been created to model the presence of two sequentially forming structures on the surface of a substrate. It gives an insight into the percentages of each structure on the surface, along with the actual adsorption process. This model provides a good fit to all applicable experimental data and has allowed the deduction of optimum immersion times. The second novel model (PIF) provides a greater insight than existing models into the individual contributions to surface coverage by both random and island growth. This allows an insight into how the monolayer surface is covered, which is critical to determine the optimum conditions for adsorption. This model also provides a good fit to the isotherm data it has been applied to. To provide a thorough understanding of the bulk properties of monolayer formation over the gold transducer, and how these properties vary with immersion time and temperature, various measurement techniques have been employed. Electrochemical Impedance Spectroscopy (EIS) has been the principle measurement technique used to measure the bulk properties, but confirmation studies have also been carried out including, Contact angle measurements, FTIR microscopy with BSA molecular labels, Fluorescence microscopy for small adsorbed molecules and AFM for layers assembled from macromolecules. The data generated from the different techniques show consistency with the arguments discussed in each instance. Two different IgG adsorption processes have been compared. These include direct IgG addition and a multilayered streptavidin-based process. The results indicate that IgG molecules adsorbed via the streptavidin based multilayer process are more vertically orientated and have a higher packing density of IgG molecules. Keywords: Self Assembled Monolayer, impedance-based immunoassay, Streptavidin, biotinylated IgG, mathematical adsorption modelling.en
dc.description.sponsorshipEPSRC and Immunodiagnostic Systems (IDS) Ltden
dc.language.isoenen
dc.publisherMy Institutionen
dc.subjectadsorptionen
dc.subjectequationsen
dc.subjectself assembled monolayeren
dc.subjectEDC and NHS crosslinkersen
dc.subjectstreptavidinen
dc.titleImpedance Analysis and Mathematical Modelling of Immunosensor Biolayeren
dc.typeThesis or dissertationen
dc.publisher.departmentSchool of Science and Engineeringen
dc.type.qualificationnamePhDen
dc.type.qualificationlevelDoctoralen
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