A phenylboronic acid-based smart photonic crystal hydrogel sensor for colorimetric detection of glucose

Glucose detection plays a crucial role in the treatment and management of diabetes. We herein report a simple strategy to prepare a photonic crystal hydrogel (PNAPB PCH) sensor for colorimetric detection of glucose. This sensor is composed of a poly(N-isopropylacrylamide-co-3-acrylamidophenyl boronic acid) smart hydrogel with pendent phenylboronic acid (PBA) units and embedded Fe3O4 colloidal photonic crystals (PCs), which could strongly diffract visible light and endow the hydrogel with brilliant structural colors. The PBA units could form complexes with glucose molecules, thus increasing the ionization degree of the hydrogel and expanding its volume. The volume swelling increased the adjacent distance of the Fe3O4 nanoparticles (NPs) and thereby red-shifted their diffraction wavelength. As a result, the glucose signal could be facilely converted into a color change of the hydrogel. The resultant PNAPB PCH biosensor displayed high sensitivity and selectivity to glucose as well as excellent thermosensitive detection performances. In addition, by taking advantage of the unique thermosensitivity of the introduced PNIPAM moieties on the gel network, the glucose-responded PNAPB PCH sensor could be easily regenerated via simple alternate flushing using hot/cold water without compromising its performance. Such a glucose-sensitive PCH sensor possessing the obvious advantages of portability, ease of operation, and cost-effectiveness makes it valuable for daily blood glucose monitoring and diabetes diagnosis.