Integrating Metal–Organic Framework Hybrid into Nucleic Acid–Based Hydrogel for Highly Selective Recognition and Sensitive Detection of Sarafloxacin

Metal-organic framework-based hybrids (MOFzyme) have promising applications in colorimetric aptasensors due to their highly efficient and stable catalytic activity. However, their efficient application in biosensors remains a challenging issue due to the limited reaction site and amorphous structure. Herein, we encapsulated catalase inside MOF cavities to prepare an MOFzyme with many functional groups on its surface, and the functional groups were utilized for the subsequent integration of MOFzyme into the hyaluronic acid-DNA hydrogel. Moreover, the accurate and flexible synthesis unit of the hydrogel enabled the prepared DNA hydrogel to adjust the shape to suit and encapsulate MOFzyme. Subsequently, a novel colorimetric sensing strategy for detecting Sarafloxacin (Sar) was developed based on the excellent catalytic ability mediated by MOFzyme and the stimulus responsiveness of the DNA hydrogel. In addition, an evolved aptamer with a higher affinity for Sar was obtained via a semirational design strategy and elaborately designed into a synthetic unit of DNA hydrogel, significantly improving the response sensitivity and specificity of the aptasensor. The constructed aptasensor exhibited a wide linear detection range of 0.003 and 200 ng/mL with a low detection limit of 2.06 pg/mL. Above all, this work provides a novel and sensitive way to determine hazardous substances in food and environments.