Electrochemical Biosensors Based on Thiol and N-Heterocyclic Carbene Self-Assembled Monolayers
| dc.contributor.advisor | Birss, Viola I. | |
| dc.contributor.author | Mayall, Robert Matthew | |
| dc.contributor.committeemember | Amrein, Matthias W. | |
| dc.contributor.committeemember | Sutherland, Todd C. | |
| dc.contributor.committeemember | Sanati-Nezhad, Amir | |
| dc.contributor.committeemember | Mauzeroll, Janine | |
| dc.date | 2019-06 | |
| dc.date.accessioned | 2019-05-02T21:10:54Z | |
| dc.date.available | 2019-05-02T21:10:54Z | |
| dc.date.issued | 2019-04-29 | |
| dc.description.abstract | Monitoring for the presence of biological threats is of great importance from both a healthcare and military perspective. Traditional monitoring technologies fall into two categories, detection, which relies on quick (<20 minute) sensing of a potential threat agent, and identification, which provides specific information about the nature of the threat agent but takes longer to perform (typically ca. 1 hour). The focus of this thesis is to develop novel sensor platforms capable of performing both detection and identification methodologies utilizing an electrochemical biosensor approach. The fabrication of a detection biosensor was based on the specificity of Toll-Like Receptors (TLRs), which are a class of proteins found in the innate immune system of animals. These proteins detect specific markers for classes of biological agents, with TLR-4 detecting the presence of Gram-negative bacteria. TLR-4 was tethered to a Au electrode via an alkylthiol self-assembled monolayer (SAM) using an oriented approach to mimic the natural conformation that the protein adopts in the immune system. This sensor system was shown to detect the presence of Gram-negative bacteria (from 1 to 105 cells/mL) in phosphate buffer solutions, while remaining insensitive towards both Gram-positive and viral challenges. This sensor was then modified in order to increase the measured currents and enable the transition to a deployable instrumentation system. The incorporation of trace levels of ferrocene moieties into the SAM was studied, producing a simple method to increase the currents by >3 orders of magnitude. When applied to the TLR-4 biosensor platform, no loss of sensitivity or specificity was observed. The higher currents allowed for the translation of the TLR-4 biosensor onto an inexpensive open-source potentiostat system that is field-deployable. A novel SAM chemistry, utilizing ultra-stable N-heterocyclic carbenes (NHCs), was also studied for use as a platform in the development of biosensors. A sensor capable of detecting intact measles virions, without any pretreatment steps, was developed, for the first time, using either NHC or comparable alkanethiol SAMs. While both systems showed excellent specificity, the NHC system produced significantly larger signals over the same range of measles virus concentrations as the alkanethiol system. Importantly, the sensors based on the NHC SAMs were able to detect the presence of measles virions after two weeks of storage, whereas the alkanethiol SAMs could not. Overall, it is clear that these sensors are strong candidates for the monitoring of biological threat agents. The oriented approach to protein attachment and the incorporation of ferrocene into the SAMs demonstrated excellent detection on par or better than other published work. This thesis also represents the first report of an electrochemical biosensor based on NHC SAMs, showing a significantly better response than comparable alkanethiol SAMs and far superior stability towards storage of a pre-fabricated sensor. Combined, the work of this thesis demonstrates that electrochemical biosensors hold great promise as sensors for both detection and identification purposes in healthcare and military settings. | en_US |
| dc.identifier.citation | Mayall, R. M. (2019). Electrochemical Biosensors Based on Thiol and N-Heterocyclic Carbene Self-Assembled Monolayers (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. | en_US |
| dc.identifier.doi | http://dx.doi.org/10.11575/PRISM/36441 | |
| dc.identifier.uri | http://hdl.handle.net/1880/110258 | |
| dc.language.iso | eng | en_US |
| dc.publisher.faculty | Science | en_US |
| dc.publisher.institution | University of Calgary | en |
| dc.rights | University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. | en_US |
| dc.subject | Biosensor | en_US |
| dc.subject | Monolayer | en_US |
| dc.subject | Electrochemistry | en_US |
| dc.subject.classification | Biochemistry | en_US |
| dc.subject.classification | Materials Science | en_US |
| dc.title | Electrochemical Biosensors Based on Thiol and N-Heterocyclic Carbene Self-Assembled Monolayers | en_US |
| dc.type | doctoral thesis | en_US |
| thesis.degree.discipline | Chemistry | en_US |
| thesis.degree.grantor | University of Calgary | en_US |
| thesis.degree.name | Doctor of Philosophy (PhD) | en_US |
| ucalgary.item.requestcopy | true |