In the body, pH-responsive hydrogels swell or shrink depending on the pH in different locations or metabolic states. This volume change can control drug release or, as discovered by Luke Andrew Connal, University of Melbourne, Australia, and colleagues, activate a sensor.
The team synthesized a fluorescent biosensor based on pH-responsive hydrogels. Thioflavin T is a fluorescent dye used to detect the effects of Alzheimer’s and other neuro-degenerative diseases. To form the biosensor, the researchers used Thioflaven T as a cross-linker to covalently attach to polyethylene glycol methacrylate chains and form the hydrogel network.
At acidic pH, the hydrogel swelled but gave off little emission due to the deionization of the Thioflavin T molecules. At neutral pH, swelling began to decrease and the hydrogel gave off a strong blue emission under UV light. Basic pHs shrunk the hydrogel further and decreased emission. The sensor is reusable, and in addition, drugs could be loaded into the hydrogel to form a combined drug delivery/biomedical monitoring system.
- pH-responsive fluorescent hydrogels using a new thioflavin T cross-linker,
Zeyun Xiao, Ross Andrew Lennox Wylie, Emma Ruth Lucille Brisson, Luke Andrew Connal,
J. Polym. Sci. A Polym. Chem. 2015.