Colorimetric detection of interleukin-6 and other inflammatory biomarkers using aptamer- and immuno-based nanobiosensors

Gomes de Pinho Baptista, Maria (2025) Colorimetric detection of interleukin-6 and other inflammatory biomarkers using aptamer- and immuno-based nanobiosensors. Doctoral thesis, University of East Anglia.

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Abstract

Diagnostic tools for biomarker detection are essential in modern healthcare, playing a critical role in early disease identification, monitoring, and personalised treatment. Research on the improvement of these diagnostic tools is vital for addressing current and future health challenges. Interleukin-6 (IL-6) is a multifunctional cytokine that plays a pivotal role in the regulation of inflammatory and immune responses. IL-6 levels in the bloodstream rise shortly after an inflammatory stimulus, and a continuous elevation for 24 hours has been associated to organ dysfunction and potentially fatal outcomes. Consequently, improving current approaches to IL-6 detection, making them faster and more accessible for early detection and disease management, is a priority to improve patient outcomes.

In this thesis, different optical nanobiosensing approaches for the colorimetric detection of murine and human IL-6 were investigated to systematically evaluate the effect of the nanomaterial size and shape, the biorecognition molecule, and the ligand density on the assay sensitivity. To that end, different synthetic methodologies were explored to obtain homogenous and quasi-spherical ca. 40 nm gold nanoparticles (AuNPs) that were compared to commercially available ones. After confirmation of the reproducibility of the synthetic method, the in-house synthesised AuNPs and commercially available gold nanorods (AuNRs) and gold nanoshells (AuNSs) were functionalised using aptamers and antibodies.

The functionalised AuNPs and AuNRs were used in aggregation-based assays for the detection of murine IL-6 in-solution by monitoring changes in their surface plasmon absorption band using ultraviolet-visible spectroscopy. The aptamer- and antibody-functionalised AuNPs were also used for the detection of IL-6 in a filter-based aggregation assay and evaluated by visual observation and signal intensity quantification.

The functionalised AuNPs, AuNRs, and AuNSs were used in a paper-based assay for the detection of both murine and human IL-6. The assay format was a simplified version of a dipstick assay, where IL-6 was directly deposited into the nitrocellulose membrane. The results were monitored visually, by the appearance of a signal, and the signal intensity was quantified to better understand the behaviour of the functionalised nanomaterials.

In addition to IL-6, other inflammatory biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) can provide crucial information about the progression of inflammation and the type of pathogen involved. Therefore, the simultaneous detection of these three biomarkers can provide critical insight about the nature and severity of the inflammatory response. With that in mind, functionalised AuNPs with aptamer for the detection of PCT, and antibodies for the detection of IL-6 and CRP were integrated in a vertical flow assay format for the simultaneous detection of the three inflammatory biomarkers. The readout of this assay was visual and the signal intensity was quantified for better comparison of the results.

The research undertaken during this thesis explored multiple nanoplatforms configurations using in-solution and paper-based colorimetric assays for the rapid detection of inflammatory biomarkers, mainly IL-6. The findings contribute valuable insights for the development and improvement of rapid diagnostic tools for IL-6 detection, highlighting that the optimal nanoplatform configuration is often determined experimentally rather than through prediction.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Chemistry, Pharmacy and Pharmacology
Depositing User:	Chris White
Date Deposited:	29 Jan 2026 13:38
Last Modified:	29 Jan 2026 13:38
URI:	https://ueaeprints.uea.ac.uk/id/eprint/101792
DOI:

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