SERS-based nanoparticle biodetection using carbohydrate-lectin interactions

  • Jonathan Robert Henry Simpson

Student thesis: Doctoral Thesis

Abstract

Endogenous biological processes including cellular recognition, motility and differentiation together with infection often result from carbohydrate-based interactions. Investigation into glycobiological interactions using sugar-coated nanoparticles are the basis for the research described herein.Metallic nanoparticles were coated with a variety of thiol-based linker molecules. Heterobifunctional PEG (carboxyl/thiol) molecules were found to be most successful in preventing non-specific aggregation. The carboxylic acid functionality of the PEG molecules used allowed for subsequent coupling of a variety of carbohydrates to the nanoparticle surface. This resulted in the production of glyconanoparticles with unique surface functionality, for example, glucose or galactose. Additionally, functionalising the particles with Raman reporter molecules (RRMs) resulted in the measurement of surface enhanced Raman scattering (SERS) signals. Aggregation of the glyconanoparticles in the presence of a variety of carbohydrate-binding proteins (lectins) was measured via changes in the extinction profile, size and the SERS response of those particles. Nanoparticle aggregation was used for the sensitive detection of plant lectins, including the Concanavalin A and Jacalin lectin and also bacterial lectins including cholera toxin B subunit (CTB). CTB was detected sensitively, selectively and rapidly by using glyconanoparticles coated in a mixture of different carbohydrates (mixed-monolayers of galactose and N-acetylneuraminic acid). Detection was possible in both buffer and synthetic freshwater conditions, demonstrating the use of these glyconanoparticles in detecting a target in complex samples.By exploiting the reversible nature of carbohydrate-lectin interactions, it was possible to use the glyconanoparticles together with the lectin ConA to develop a glucose sensor.This performed effectively across the physiological range and into the hypo/hyperglycaemic regions in buffer conditions.Finally, the glyconanoparticles were used for the detection of plant and bacterial lectins on glass substrates by initially developing a sandwich SERS assay with a view to eventually creating SERS-based carbohydrate microarrays.
Date of Award1 Oct 2015
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorDuncan Graham (Supervisor) & Karen Faulds (Supervisor)

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