Towards the Development of Biodegradable Sensors from Smart Hydrogels

The performance of environmentally responsive hydrogels can be greatly improved by fabricating them on the micro and nanoscale. A smaller spatial scale offers enhanced mass transfer and chemomechanical response. As part of a microscale sensing platform these networks can offer unriveled reliability and reproducibility. We have previously shown the effectiveness of this approach in the design of micropatterned ultrasensitive microcantilever pH-sensors. The work here describes the design of pH-responsive hydrogels capable of tunable hydrolytic degradation for use in microscale sensing applications. A novel hydrogel consisting of poly(methacrylic acid), (PMAA), crosslinked with poly(caprolactone) was synthesized via UV-initiated free-radical polymerization. The swelling kinetics closely followed those of nondegradable PMAA networks. The degradation kinetics were studied by swelling hydrogel disks in phosphate buffered saline (PBS) solution at 37°C for 60 days to mimic biological conditions. The molecular weight between crosslinks was found to increase linearly with time. Overall, this hydrogel demonstrates favorable swelling and degradation kinetics to function in degradable microsensing applications.