Biosensors for exhaled breath condensate analysis
File(s)
Author(s)
Zhang, Shulin
Type
Thesis
Abstract
This thesis focuses on the development of biosensors for the analysis of exhaled breath condensate (EBC) biomarkers to provide rapid, precise, and point-of-care measurements. Although EBC analysis shows potential for non-invasive diagnosis and monitoring of lung illnesses, difficulties in sample collection and the requirement for expensive, offline laboratory studies have constrained its clinical application. To address these restrictions, our group developed a portable, user-friendly device that facilitates dependable, point-of-care EBC analysis. The biosensors were specifically designed to interact with this system, facilitating efficient, real-time monitoring of EBC biomarkers.
This project aims to develop biosensors for measuring important biomarkers—lactate, nitrate, and nitrite—in EBC. Disposable gold sensors were modified with Prussian blue and lactate oxidase and applied for lactate quantification. These sensors exhibited strong quantitative consistency with reference methodologies (LC/MS and fluorimetry). Preliminary clinical investigations revealed positive relationships between EBC and blood lactate levels.
Gold sensors enhanced with copper and graphene oxide were developed for the quantification of nitrate and nitrite. Preliminary experiments using rod electrodes in an oxygen-deprived environment successfully measured reduction peaks for both analytes. Disposable sensors showed fit-of-purpose nitrate quantification in the presence of dissolved oxygen. However, the quantification of nitrite was not successful and requires further investigation. Initial tests with EBC samples showcased the potential of the sensor for nitrate analysis, although its clinical application has not yet been demonstrated.
The stability of the reference electrode in disposable sensors was examined, with three gel modifications evaluated to minimise chloride ion migration. All gels demonstrated significant enhancements in sensor stability. Subsequent studies will enhance the sensors and perform extensive clinical trials to verify their reliability in quantifying EBC biomarkers.
This project aims to develop biosensors for measuring important biomarkers—lactate, nitrate, and nitrite—in EBC. Disposable gold sensors were modified with Prussian blue and lactate oxidase and applied for lactate quantification. These sensors exhibited strong quantitative consistency with reference methodologies (LC/MS and fluorimetry). Preliminary clinical investigations revealed positive relationships between EBC and blood lactate levels.
Gold sensors enhanced with copper and graphene oxide were developed for the quantification of nitrate and nitrite. Preliminary experiments using rod electrodes in an oxygen-deprived environment successfully measured reduction peaks for both analytes. Disposable sensors showed fit-of-purpose nitrate quantification in the presence of dissolved oxygen. However, the quantification of nitrite was not successful and requires further investigation. Initial tests with EBC samples showcased the potential of the sensor for nitrate analysis, although its clinical application has not yet been demonstrated.
The stability of the reference electrode in disposable sensors was examined, with three gel modifications evaluated to minimise chloride ion migration. All gels demonstrated significant enhancements in sensor stability. Subsequent studies will enhance the sensors and perform extensive clinical trials to verify their reliability in quantifying EBC biomarkers.
Version
Open Access
Date Issued
2024-10-03
Date Awarded
2024-12-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
O'Hare, Danny
Publisher Department
Bioengineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)