1. Non-invasive, transdermal, path-selective and highly specific glucose monitoring on a graphene platform
- Author
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Dupont, Bertrand, Tyrrell, Rex, Guy, Richard, and Ilie, Adelina
- Subjects
616.4 ,Biosensor ,Graphene ,Glucose ,Non-invasive ,Reverse iontophoresis - Abstract
The main technology currently used in diabetic care, monitors blood glucose and involves an invasive “fingerstick” step. However, low patient compliance and non-continuous glucose monitoring imply poor management of diabetes through this technology, which could lead to adverse and potentially life threatening conditions. In this context, non-invasive glucose sensing appears as an alternative that can bring a change in the prevention and management of the diabetic condition, promising to eliminate patient resistance towards more frequent monitoring and, hence, considerably improving diabetic’s control over glycaemia. However, no non-invasive technology has yet succeeded on the market over the long term. The research field is therefore open to innovative and performant non-invasive technologies. This thesis presents the development of a non-invasive biosensor which as a core principle accesses individual, privileged glucose pathways in the skin (such as hair follicles), allowing the extraction of glucose directly from the interstitial fluid, via reverse iontophoresis (RI). The transdermally extracted glucose is then electrochemically detected in a small size sensor with very high sensitivity. A fully developed technology based on this principle will not require fingerpricking and would thus eliminate users’ main barrier to glucose monitoring. The developed sensor is enzymatic (using glucose oxidase), which electrochemically detects the produced H2O2; while the electrode material is graphene produced by Chemical Vapour Deposition, a promising carbon nanomaterial platform for biofunctionalisation and biosensing. The sensor is a miniature one (typically of 9 mm2 area, containing 24 μL of gel encasing the enzyme), with demonstrated performance parameters that are highly competitive (sensitivity of 2.89 μA.mM-1.cm-2 and limit of detection down to 1 μM), with high specificity towards glucose. The combination of this sensor with glucose extraction by reverse iontophoresis was then validated (with proportionality between subdermal and extracted glucose concentrations demonstrated); as well as enhanced extraction through targeting of hair follicles with the miniature device. The electrochemical determination of glucose concentration was further confirmed by 1H quantitative-NMR detection of glucose. Finally, several such sensors were integrated in a multiplex configuration, and independent sensing, with no cross-talk was demonstrated. The steps demonstrated and implemented so far are proof-of-concept of a highly promising non-invasive, transdermal, future technology for diabetic care.
- Published
- 2015