Multi-deformable interpenetrating network thermosensitive hydrogel fluorescent device for real-time and visual detection of nitrite

Functionalized thermosensitive hydrogel materials exhibit excellent properties for the fabrication of sensing devices that enable real-time visual detection of food safety duo to their good plasticity and powerful loading capacity. Here, a ratiometric fluorescent device based on an interpenetrating network (IPN) thermosensitive hydrogel was designed to embed functionalized Au nanoclusters (Au NCs) and Blue Carbon dots (BCDs) composites in a multi-network structure to build a sensitive hazardous material nitrite (NO 2 - ) chemsensor. The hydrogel was utilized poloxamer 407 (P407), lignin and cellulose to form stable IPN structure, which resulted in complementation and synergy, thereby strengthening its porous network structure. The combination of fluorescent nanoprobes with the porous network structure has the potential to enhance stable fluorescence signals and improve sensing sensitivity. Moreover, the thermosensitive liquid-solid transition characteristics of the hydrogel facilitate its preparation into diverse sensing devices following curing at room temperature. The hydrogel device, when combined with a smartphone system, converted image information into data information, thereby enabling the accurate quantification of NO 2 - with a detection limit of 9.38 nM in 2 s. The designed multi-functional hydrogel device is capable of real-time differentiation of NO 2 - dosage with the naked eye, offering a high-contrast, rapid-response sensing methodology for visual assessment of food freshness. This research contributes to the expansion of hydrogel materials applications and the detection of hazardous materials in food safety. • Hydrogel designed by functional thermosensitive interpenetrating network structures. • The hydrogel has good antibacterial performance and temperature sensitivity. • The hydrogel can enhance stable fluorescence signals and improve sensing ability. • The device enabling the accurate quantification of NO 2 - with a detection limit of 9.38 nM in 2 s