Jia et al. Proposed a fast and efficient appro

Jia et al. Proposed a fast and efficient approach for the instruction of responsive photonic hydrogels for the detection of aldehydes through combining monodisperse carbon-encapsulated self-assembly of Fe₃O₄ nanoparticles (NPs) and in situ photopolymerizations of polyacrylamide (PAM) hydrogels. here, via optimizing the composition and structure of photonic hydrogels, they efficaciously used responsive photonic hydrogels to visually determine aldehydes in an aqueous solution. Responsive photonic hydrogels after treatment with an aqueous formaldehyde solution, which can be attributed to the chemical reaction between the amide groups within the hydrogels and formaldehyde (in the hydroxymethylation reaction), show structural color changes, i. e. in the presence of formaldehyde gradually which changes from blue to green over time. The whole preparation procedure for these responsive photon hydrogels takes less than half-hour. further, the concentration of aldehydes can be determined by using direct observation of the structural color of photonic hydrogels, which in fact have benefits as significantly facilitating the assay process, fast instruction, visual readout, low cost, and rapid detection [344].