Hydrogels that change volume in response to specific molecular stimuli can serve as platforms for sensors, actuators and drug delivery devices. There is great interest in designing intelligent hydrogels for tissue engineering, drug delivery, and microfluidics that utilize protein binding specificities and conformational changes. Protein conformational change induced by ligand binding can cause volume phase transitions (VPTs). Here, we develop a highly selective glucose sensing protein photonic crystal (PC) hydrogel that is fabricated from genetically engineered E. coli glucose/galactose binding protein (GGBP). The resulting 2-D PC-GGBP hydrogel undergoes a VPT in response to glucose. The volume change causes the 2-D PC array particle spacing to decrease, leading to a blue-shifted diffraction which enables our sensors to report on glucose concentrations. This 2-D PC-GGBP responsive hydrogel functions as a selective and sensitive sensor that easily monitors glucose concentrations from ∼0.2 μM to ∼10 mM. This work demonstrates a proof-of-concept for developing responsive, "smart" protein hydrogel materials with VPTs that utilize ligand binding induced protein conformational changes. This innovation may enable the development of other novel chemical sensors and high-throughput screening devices that can monitor protein-drug binding interactions.
Bibliographical noteFunding Information:
We are thankful for helpful discussions with Professor Milan Mrksich, Professor William Murphy and Mr Andrew Eagle Cookouma. The authors gratefully acknowledge HDTRA for financial support (Grant No. 1-10-1-0044 and 1-15-1-0038 to SAA). This work has been supported by NSF funding for the LC-MS instrumentation in the Chemistry Department at the University of Vermont (CHE MRI-0821501, LAL Co-PI), SUNY at Plattsburgh President's Award and Mini Grant (LAL).