The impact of hollow core-shell nanozymes in biosensing: A case study of p-Fe3O4@PDA@ZIF-67

Background Nanozymes , a new class of nanomaterials , have emerged as promising substitutes for enzymes in biosensor design due to their exceptional stability, affordability, and ready availability. While nanozymes address many limitations of natural enzymes, they still face challenges, particularly in achieving the catalytic activity levels of their natural counterparts. This indicates the need for enhancing the sensitivity of biosensors based on nanozymes. The catalytic activity of nanozyme can be significantly improved by regulating its size, morphology, and surface composition of nanomaterial. Results In this work, a kind of hollow core-shell structure was designed to enhance the catalytic activity of nanozymes. The hollow core-shell structure material consists of a nanozymes core layer, a hollow layer, and a MOF shell layer. Taking the classic peroxidase like Fe 3 O 4 as an example, the development of a novel nanozyme@MOF, specifically p-Fe 3 O 4 @PDA@ZIF-67, is detailed, showcasing its application in enhancing the sensitivity of sensors based on Fe 3 O 4 nanozymes. This innovative nanocomposite, featuring that MOF layer was designed to adsorb the signal molecules of the sensor to improve the utilization rate of reactive oxygen species generated by the nanozymes catalyzed reactions and the hollow layer was designed to prevent the active sites of nanozymes from being cover by the MOF layer. The manuscript emphasizes the nanocomposite's remarkable sensitivity in detecting hydrogen peroxide (H 2 O 2 ), coupled with high specificity and reproducibility, even in complex environments like milk samples. Significance and novelty This work firstly proposed and proved that Fe 3 O 4 nanozyme@MOF with hollow layer structure was designed to improve the catalytic activity of the Fe 3 O 4 nanozyme and the sensitivity of the sensors based on Fe 3 O 4 nanozyme. This research marks a significant advancement in nanozyme technology, demonstrating the potential of structural innovation in creating high-performance, sensitive, and stable biosensors for various applications.