Structure-Activity Studies of Surface Immobilized Cytochrome c Films on Indium Tin Oxide: Solution Adsorbed and Microcontact Printed Films

Persistent Link:
http://hdl.handle.net/10150/194516
Title:
Structure-Activity Studies of Surface Immobilized Cytochrome c Films on Indium Tin Oxide: Solution Adsorbed and Microcontact Printed Films
Author:
Runge, Anne FitzPatrick
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The goal of this research project is to understand how different methods of protein immobilization affect the function and orientation of a redox active protein (cytochrome c) on an electrode surface. Cytochrome c (cyt c) is widely thought to adsorb onto negatively charged electrode surfaces with the heme pocket close to the electrode in a narrow orientation distribution that facilitates rapid electron transfer; however, a direct relationship between this orientation and the electron transfer properties has not been experimentally proven. Establishing structure-function relationships is crucial to the development of molecular devices based on immobilized proteins (e.g. biosensors). Differences in the structure and activity of two different types of protein films have been studied by comparing their surface coverage, orientation distributions and electrochemical behavior on the indium tin oxide (ITO) electrode surface. Films were formed by printing cyt c onto the ITO surface using microcontact printing (uCP) and by direct adsorption out of solution.A combination of surface-sensitive spectroscopic techniques was used to probe the prosthetic heme group of the protein, and by extension, the protein as a whole. Attenuated total reflectance (ATR) spectroscopy was used to measure the surface coverage and second order parameter of the cyt c films on glass and ITO. Differences in the surface coverage depended on the substrate and the method of deposition. Total internal reflectance fluorescence (TIRF) was used to measure the fourth order parameter of these films and the angle between the absorption and emission dipoles of the Zinc substituted heme. Using the second and fourth order parameters, orientation distributions were calculated using the maximum entropy method. The electrochemical behavior of these films was investigated using cyclic voltammetry. uCP films have a slightly slower rate of electron transfer and a lower electroactive surface coverage compared to films formed by solution adsorption. The percent of electroactive proteins in solution adsorbed films was about 50 %, while for uCP films it was only about 5 %.The ability to directly probe the total surface coverage and orientation distribution of molecules on the ITO electrode surface, as developed here, could be useful in many fields where optically transparent electrodes are in wide use, such as solar cells and organic light emitting diodes.
Type:
text; Electronic Dissertation
Keywords:
Chemistry
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Saavedra, Steven Scott
Committee Chair:
Saavedra, Steven Scott

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleStructure-Activity Studies of Surface Immobilized Cytochrome c Films on Indium Tin Oxide: Solution Adsorbed and Microcontact Printed Filmsen_US
dc.creatorRunge, Anne FitzPatricken_US
dc.contributor.authorRunge, Anne FitzPatricken_US
dc.date.issued2005en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe goal of this research project is to understand how different methods of protein immobilization affect the function and orientation of a redox active protein (cytochrome c) on an electrode surface. Cytochrome c (cyt c) is widely thought to adsorb onto negatively charged electrode surfaces with the heme pocket close to the electrode in a narrow orientation distribution that facilitates rapid electron transfer; however, a direct relationship between this orientation and the electron transfer properties has not been experimentally proven. Establishing structure-function relationships is crucial to the development of molecular devices based on immobilized proteins (e.g. biosensors). Differences in the structure and activity of two different types of protein films have been studied by comparing their surface coverage, orientation distributions and electrochemical behavior on the indium tin oxide (ITO) electrode surface. Films were formed by printing cyt c onto the ITO surface using microcontact printing (uCP) and by direct adsorption out of solution.A combination of surface-sensitive spectroscopic techniques was used to probe the prosthetic heme group of the protein, and by extension, the protein as a whole. Attenuated total reflectance (ATR) spectroscopy was used to measure the surface coverage and second order parameter of the cyt c films on glass and ITO. Differences in the surface coverage depended on the substrate and the method of deposition. Total internal reflectance fluorescence (TIRF) was used to measure the fourth order parameter of these films and the angle between the absorption and emission dipoles of the Zinc substituted heme. Using the second and fourth order parameters, orientation distributions were calculated using the maximum entropy method. The electrochemical behavior of these films was investigated using cyclic voltammetry. uCP films have a slightly slower rate of electron transfer and a lower electroactive surface coverage compared to films formed by solution adsorption. The percent of electroactive proteins in solution adsorbed films was about 50 %, while for uCP films it was only about 5 %.The ability to directly probe the total surface coverage and orientation distribution of molecules on the ITO electrode surface, as developed here, could be useful in many fields where optically transparent electrodes are in wide use, such as solar cells and organic light emitting diodes.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectChemistryen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorSaavedra, Steven Scotten_US
dc.contributor.chairSaavedra, Steven Scotten_US
dc.contributor.committeememberArmstrong, Neal R.en_US
dc.contributor.committeememberGhosh, Indraneelen_US
dc.contributor.committeememberMendes, Sergio B.en_US
dc.contributor.committeememberPemberton, Jeanneen_US
dc.identifier.proquest1194en_US
dc.identifier.oclc137354307en_US
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