Carbohydrate-based detection as the basis of new diagnostics for infectious diseases

Hernando Callejo, Pedro J. (2022) Carbohydrate-based detection as the basis of new diagnostics for infectious diseases. Doctoral thesis, University of East Anglia.

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Carbohydrates cover the surface of mammalian and bacterial cells, playing crucial roles in biological processes including pathogen-host recognition. The intrinsically weak carbohydrate-mediated interactions are compensated in Nature by a multivalent exhibition of the sugar ligands generating a “velcro” type of interaction known as glycocluster effect.

There is an unmet need for simple, reliable, and portable devices for the early detection of pathogens. In this research work, we explored the development of a rapid carbohydrate-based assay for the detection of glycan-binding proteins, lectins, in relation to the detection of bacteria. To allow a visual read-out of the test, gold nanoparticles have been applied on a paper-based diagnostic assay.

A set of carbohydrates was chemically and/or enzymatically modified with an azidopropyl tether, allowing the functionalisation of alkyne-modified bovine serum albumin through Cu(I)-catalysed alkyne-azide cycloaddition. The multivalent neo-glycoproteins were immobilised on the surface of ca. 40 nm gold nanoparticles following passive adsorption methodology. The synthesised glyconanoparticles were employed as detection agents in a dipstick assay for the detection of a selection of lectins. To further understand the impact of the nanoparticle size and the presentation of glycans on the assay performance, ca. 150 nm gold nanoshells and ca. 40 nm gold nanoparticles covalently functionalised with glycans were investigated.

A lectin relevant to the early detection of the opportunistic pathogen Pseudomonas aeruginosa was targeted. A carbohydrate-based ligand was tailored for the detection of the P. aeruginosa surface lectin LecA. The detection of LecA in bacterial samples employing antibodies was investigated through Western Blot. Preliminary results against P. aeruginosa strain are presented using flow cytometry to evaluate the potential detection of the target bacteria exploiting its interaction with glyconanoparticles.

The results presented in this thesis show the potential of glyconanoparticles for the cost-effective detection of lectins, paving the way for the rapid detection of pathogens.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 30 Jan 2023 14:46
Last Modified: 30 Jan 2023 14:46

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