High Entropy Layered Double Hydroxide Nanozyme for Sensitive Detection of Tetracycline

Monitoring and controlling antibiotic residues in the environment are critical for minimizing bacterial resistance, preserving microecological equilibrium, and protecting human health. Core competencies of the sensor include sensitivity, selectivity, and mobility. It is still very difficult to combine these qualities in a single sensor for effective tetracycline (TC) detection. Herein, a flower-like spherical structure of high-entropy layered double hydroxide Fe 0.45 Co 0.45 Ni 0.45 Cu 0.45 Zn 0.45 -LDH (HE-LDH) was prepared with superior peroxide-like activity to convert hydrogen peroxide (H 2 O 2 ) to hydroxyl radicals (•OH) ( K m = 0.075 mM of H 2 O 2 ). Because of the significant reactivity that exists between TC and •OH produced in the catalytic system, a simple colorimetric method for TC detection was established. As for TC detection performance, the linear range and limit of detection were 100–1000 and 25.6 nM in the solution colorimetric mode, respectively. Also, 100–800 nM of the linear range and 32.2 nM of limit of detection were obtained in the paper colorimetric mode. The developed method also exhibited good selectivity for TC over other antibiotics, amino acids, and ions. Furthermore, the use of actual water sample analysis demonstrated excellent self-calibration and satisfactory recovery of 95.4–103.1%. This study offers significant progress toward developing the use of nanozymes with good enzyme-like activity in antibiotic detection, accelerating the development of efficient and portable antibiotic sensors.