Thesis
Magnetically enhanced sensing: advancements in SERS-active magnetic particle development
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2023
- Thesis identifier
- T16782
- Person Identifier (Local)
- 201967869
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Magnetic beads (MBs) have a myriad of uses in medicine and biological applications. However, the need for improved sensitivities of biomolecule detection in applications that use MBs remains highly desired within these fields. Conventionally, MBs are only used for separation and a separate entity is used for detection, which increases the time and lowers the sensitivity of the approach. Surface enhanced Raman scattering (SERS) is a highly selective and sensitive technique in bioanalysis; yet research in applying both magnetic beads and SERS in a single entity is limited. The overall aim of this research was to investigate the feasibility and performance of merging the two modalities to create a stable, reproducible SERS active magnetic particle that has the potential to be applied for biomolecule detection. Initially, micron-sized MBs were assessed through two routes of surface modification: first used a seed mediated growth to produce gold nanoparticles (AuNPs) to the surface of the MBs with the addition of Raman reporters and second utilized pre-synthesised AuNP aggregates possessing strong SERS signal intensities. The most promising method was found to be the addition of AuNP aggregates which were secured with a thin SiO2 layer before functionalisation with a carboxyl (COOH) polymer, forming SERS-MBs. These findings were also applied to smaller magnetic nanoparticles (MNPs), where the addition of AuNP aggregates was also applied. Two different functionalities of COOH & SiO2 coatings were explored resulting in SERS-MNPs. Integration of both micro and nano SERS magnetic particles into a surface-based assay concept was performed to determine the practicality of capture and detection from a single entity. SERS-MBs and SERS-MNPs were conjugated with specific antibodies for the capturing of Methicillin-resistant Staphylococcus aureus (MRSA) and Listeria monocytogenes (L. mono), and evaluated within the sandwich assay concept. Micro-sized SERS-MBs displayed issues with sandwich interaction disruption and charge aggregation upon capturing of the bacteria. Whereas smaller SERS-MNPs functionalised with SiO2, exhibited stable interactions when capturing bacteria strains, and also minimal interference to the sandwich complex formation. SERS-MNPs were able to extract washed MRSA bacteria within a range of 102-105 CFU/mL. Extraction of L. mono using SERS-MNPs was successful from both washed and broth matrices within a range of 10-105 CFU/mL. Furthermore, a duplex detection was also demonstrated with the capturing of both bacteria strains from washed and broth mixtures respectively. Overall, the development of SERS active magnetic particles was achieved for micron and nano sized particles. Findings show SERS-MNPs in particular could potentially be integrated into a variety of assay formats for capture and multiplex detection of biomolecules.
- Advisor / supervisor
- Graham, Duncan
- Faulds, Karen
- Resource Type
- DOI
- Embargo Note
Relations
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File | 2023-12-13 | Embargo |