Europium functionalized porphyrin-based metal-organic framework heterostructure and hydrogel for visual ratiometric fluorescence sensing of sulfonamides in foods

Protecting human health and ensuring food security require the swift and accurate detection of sulfonamides (SAs) residues in foods. Herein, we proposed an Eu-postfunctionalized bimetallic porphyrin metal-organic framework (PCN-221(Zr/Ce)@Eu-DPA-H 4 btec) synthesized solvothermally for fluorescence sensing. The PCN-221(Zr/Ce)@Eu-DPA-H 4 btec fluorescent sensor demonstrated excellent stability and high selectivity to SAs, and the detection limits of sulfamethazine (SM 2 ), sulfamerazine (SMR), and sulfamethoxydiazine (SMD) were as low as 56 nmol/L, 45 nmol/L, and 56 nmol/L, respectively. The PCN-221(Zr/Ce)@Eu-DPA-H 4 btec fluorescent sensor was successfully applied for the detection of SM 2 , SMR, and SMD in real pork and milk samples, with satisfactory recoveries (81.2–118.3%) and high precisions (RSDs <8.2, n  = 3). Combining the optical properties of the nanohybrids, PCN-221(Zr/Ce)@Eu-DPA-H 4 btec integrated fluorescent hydrogels were innovatively prepared for visual sensing of SM 2 , SMR, and SMD. This study provides an uncomplicated and sensitive method for SAs detection in food matrices.