Host–Guest Interaction and Hydrogen Bonding Cross-Linking Actuated Smart Two-Dimensional Photonic Hydrogel Sensor of l-Histidine

Histidine (His) is an essential amino acid that is closely related to the physiological activities of the human body and human health, being used as a biomarker and therapeutic drug for some diseases. It is desirable to accurately and facilely detect His. Here, an l-histidine (l-His)-sensitive smart two-dimensional photonic hydrogel sensor (CD-2DPCH) was fabricated by modifying NH2-β-cyclodextrin (NH2-β-CD) onto the poly(acrylamide-Co-acrylic acid) hydrogel containing polystyrene two-dimensional photonic crystal array (PS-2DPC). The volume of the CD-2DPCH sensor shrinks upon response to l-His due to the host–guest interaction between NH2-β-CD attached in the hydrogel chains and l-His and the hydrogen bonding interaction between l-His and amides groups on the hydrogel chains. The particle spacing change of ∼95 nm for the PS-2DPC in the hydrogel is achieved, and the chiral recognition of l-His is realized. The particle spacing change of the prepared CD-2DPCH shows a good linear correlation when the l-His concentration changes from 0.1 to 1 and 10 to 400 μM, and the limit of detection is 58 nM. The constructed smart photonic hydrogel sensor was successfully applied to determine l-His in human serum and milk. The fabrication of the sensor is facile, and the detection does not need sophisticated instruments, providing a facile and effective way to identify l-His and a good strategy for sensing other amino acids by modifying different recognition groups.