The development and validation of hydrogel-based microneedle platforms for the diagnosis of skin cancer
File(s)
Author(s)
Daniels, Connor
Type
Thesis
Abstract
Melanoma is the fifth most diagnosed cancer in the UK and the USA and is responsible for 90% of skin cancer deaths, despite representing only 1% of all skin cancers. Current diagnostic practices rely on invasive skin biopsies followed by microscopic or histochemical analysis. These procedures are often uncomfortable, time-consuming and costly. Moreover, with fewer than 10% of biopsies yielding positive results, the majority are unnecessary, underscoring the urgent need for less invasive diagnostic alternatives.
This thesis presents the development of a hydrogel-coated microneedle platform designed to capture tumour-derived miRNA from skin interstitial fluid (ISF) using peptide nucleic acid (PNA) capture probes. To enable this, various chemical modifications of sodium alginate were investigated to conjugate PNA probes while maintaining the hydrogel's structural integrity. The ability of these alginate-PNA conjugates to capture tagged DNA was evaluated in vitro using fluorescence-based imaging. Additionally, an electrochemically active DNA/PNA intercalator was synthesised to facilitate multiplexed electrochemical detection of nucleic acids. Dysregulated miRNA profiles in ISF were studied using melanoma and squamous cell carcinoma (SCC) mouse models. Based on these findings, bespoke hydrogel microneedle patches were fabricated, characterised, and tested for their ability to absorb ISF and quantify miRNA using RT-qPCR.
The results demonstrate that the microneedle platform effectively absorbs ISF and that PNA-functionalised hydrogels can detect nucleic acids in vitro, highlighting their potential as a non-invasive diagnostic tool. Mouse studies revealed that ISF is a superior source of miRNA compared to blood, supporting its promise as an alternative liquid biopsy medium for diagnosing skin cancer. Together, these advancements establish the groundwork for a minimally invasive point-of-care diagnostic device, reducing the need for painful and often unnecessary skin biopsies.
This thesis presents the development of a hydrogel-coated microneedle platform designed to capture tumour-derived miRNA from skin interstitial fluid (ISF) using peptide nucleic acid (PNA) capture probes. To enable this, various chemical modifications of sodium alginate were investigated to conjugate PNA probes while maintaining the hydrogel's structural integrity. The ability of these alginate-PNA conjugates to capture tagged DNA was evaluated in vitro using fluorescence-based imaging. Additionally, an electrochemically active DNA/PNA intercalator was synthesised to facilitate multiplexed electrochemical detection of nucleic acids. Dysregulated miRNA profiles in ISF were studied using melanoma and squamous cell carcinoma (SCC) mouse models. Based on these findings, bespoke hydrogel microneedle patches were fabricated, characterised, and tested for their ability to absorb ISF and quantify miRNA using RT-qPCR.
The results demonstrate that the microneedle platform effectively absorbs ISF and that PNA-functionalised hydrogels can detect nucleic acids in vitro, highlighting their potential as a non-invasive diagnostic tool. Mouse studies revealed that ISF is a superior source of miRNA compared to blood, supporting its promise as an alternative liquid biopsy medium for diagnosing skin cancer. Together, these advancements establish the groundwork for a minimally invasive point-of-care diagnostic device, reducing the need for painful and often unnecessary skin biopsies.
Version
Open Access
Date Issued
2025-01-02
Date Awarded
01/12/2025
License URL
Advisor
Ladame, Sylvain
Publisher Department
Department of Bioengineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)