Stimuli-sensitive hydrogel materials for sensing and drug delivery
Mac Kenna, Nicky (2015) Stimuli-sensitive hydrogel materials for sensing and drug delivery. PhD thesis, Dublin City University.
Full text available as:
The application of stimuli-sensitive hydrogels in the fabrication of smart devices has become increasingly popular with many research groups and industries. In addition to their ability to experience large reversible transitions in their swelling behaviour due to small physiological or environmental changes, they are also often highly biocompatible, versatile and possess a high storage capacity for the immobilisation of biomolecules. Several transduction methods are currently employed for monitoring the swelling response of these materials, frequently these are based on optical and mechanical methods. Electrochemical transduction has not been investigated as thoroughly but would offer significant benefits in terms of direct coupling with microelectronics, reliability and the possibility of mass production of low-cost disposable electrode devices amenable to miniaturisation. This work demonstrates that electrochemical impedance spectroscopy can be used to track hydrogel swelling in response to target analytes. Highly sensitive detection was achieved based on resistance changes of a pH-sensitive hydrogel in response to glucose. As it demonstrated good potential as a sensing platform, the applicability of this system for detecting other analytes which can elicit a pH change and are challenging in terms of limit of detection requirements was subsequently investigated. The hydrogel was modified to detect β-D-glucuronidase, a marker compound for E.coli.
Intelligent materials are also highly desirable for controlled drug delivery applications. In comparison with traditional routes of drug administration (i.e. oral and injection methods), on-demand drug delivery offers safer, more effective medical treatment by enabling site-specific administration with on-off regulation in real time. Consequently, the synthesis and characterisation of a novel electroactive hydrogel composite and its potential application in electro-stimulated drug delivery were explored.
Finally, numerous strategies were investigated to improve the swelling rate to overcome the slow response time associated with the hydrogel system. A new fabrication route for superporous hydrogels was investigated and shown for the first time to be a viable synthesis method for hydrogel systems which may be limited by pH or templating restrictions. A dramatic reduction in response time, from hours to seconds, was demonstrated. If coupled with impedimetric transduction, rapid, highly sensitive analyte detection could be achieved which would offer significant benefits and advance the application of hydrogels in smart devices.
Archive Staff Only: edit this record