Porphyrinic metal-organic framework PCN-224 supported Prussian blue enables selective detection of casein and phytic acid.

Monitoring casein and phytic acid content is of great significance for food safety and human health. In this paper, porphyrinic metal-organic framework PCN-224 supported Prussian blue (PCN-224@PB) nanoprobe was constructed by in-situ growth of PB on PCN-224 layer. The supported PCN-224 not only reduces the size and improves the dispersity of PB, but also provides specific affinity for casein and phytic acid. Based on the formation of Zr-OP structure, the peroxidase (POD)-like activity of PCN-224@PB is inhibited when encountering casein. In the presence of phytic acid, the deposited PB is decomposed, thus recovering the fluorescence of PCN-224 quenched by PB. The constructed nanoprobe exhibits high sensitivity with a limit of detection of 0.25 μg/mL for casein and 0.18 μM for phytic acid detection, respectively. In addition, PCN-224@PB shows excellent sensing performance in milk, beverage, corn and cells samples, with casein and phytic acid recoveries ranging from 94.30 % to 103.20 %, further demonstrating its feasibility in real sample analysis.