LIGAND-BASED BIOSENSOR PLATFORMS FOR RAPID DETECTION OF BACTERIA AND CANCER

• Author / Creator

  Etayash, Hashem R. Ali

• The availability of robust and handheld devices for detection is of growing importance in environmental safety, food analysis, and human diagnostic areas. The currently accessible approaches for detection of bacteria and/or diagnosing cancer, suffer from a number of constraints that hinder their wide-scale applications, such as stability, sensitivity, specificity and the time-independent functionality that is needed for real-time analysis. Identification of bacteria, for instance, has relied exclusively on specific microbiological culture media to grow, segregate and then enumerate only existing viable bacterial cells. This traditional method of detection is inconvenient, labor-intensive, time-consuming, and entails trained personnel in equipped laboratory settings. Likewise, examining cancer is mostly implemented through techniques like mammography, colonoscopy, echocardiogram, ultrasound exams, magnetic resonance imaging (MRI) and [18F] fluorodeoxyglucose positron emission tomography, which are typically followed by ex-vivo biopsies and further checkups. These methods are inconvenient, very expensive, and time-consuming, require skilled trainees and are occasionally not accurate in diagnosis; thus, they may lead to unnecessary treatment, false treatment or an actual disease go untreated. In this dissertation, I present preliminary studies towards the development of highly reliable, cheap and noninvasive ligand-based platform technologies that can be used to detect bacteria and/or to identify breast cancer biomarkers. In chapter 1, a general introduction to the current diagnostic methods and the challenges they face are presented. Chapters 2 and 3 report novel biosensing approaches for detecting pathogenic foodborne Listeria monocytogenes (L. monocytogenes) using an antimicrobial peptide (AMP) from class IIa bacteriocins and monoclonal antibodies (mAbs) assimilated in an electrochemical impedance spectroscopy (ESI) and microcantilever sensors (MCS). The results demonstrated a label-free detection of L. monocytogenes at very low concentrations (down to 1 × 103 CFU per mL) and also highlighted the feasibility of using short-ligand AMPs for selective detection of bacteria alternatively to mAbs as they are cheaper, hold better stability and easier to produce. In chapters 4, 5 and 6, rapid and non-invasive tools for spotting breast cancer biomarkers, including circulating tumor cells (CTCs) and breast cancer cell-derived exosomes, are presented. The results showed the capability of peptide-based MCS to detect CTCs (represented by MCF7 spiked human blood samples) at a limit of 50 – 100 cells per mL with a capture yield of 80% from whole blood samples. Exosomes from breast cancer cell lines were also selectively identified by targeting over-expressed membrane-proteins CD24, CD63, EGFR, and GPC1, with an excellent selectivity was achieved when targeting the cell-surface proteoglycan, at extraordinary limits (∼200 exosomes per mL, ∼0.1 pg mL−1). The current research emphasizes the development of portable, non-invasive ligand-based nano and micro platform technologies for rapid detection of pathogenic foodborne bacteria and breast cancer biomarkers.

• Subjects / Keywords

  • Bacterial resistance
  • Cancer markers
  • Diagnosis

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R37W67M64

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.