Phosphatase-like nanozymes with tailed selectivity and enhanced activity for endotoxin sensing

Endotoxin sensing has been receiving increasing attention as the endotoxin concentration is an important index for evaluating bacterial contamination and infection. The gold-standard sensing method based on horseshoe crab deformed cell lysate analysis (LAL) has been facing great challenges including high cost and animal ethical issues, which encourages researchers to explore alternative sensing probes to LAL. Herein, using 3-aminobenzoboric acid as a functional reagent, nitrogen and boron doped CeO₂ nanozymes with phosphatase activity are successfully designed and prepared. Interestingly, the introduced nitrogen and boron elements endows the nanozymes with obviously enhanced catalytic activity and high selectivity to endotoxin due to the specifical interaction between endotoxin and boric acid residue groups. Accordingly, the limit of detection of the as-prepared fluorescent liquid phase sensor is as low as 5.17 ng mL^-1 within the linear range of 20-200 ng mL^-1. Impressively, the detection time of the fabricated sensor is only 10 min and the sensor shows extremely high selectivity for lipopolysaccharide, which exhibits great application potential as alternative to traditional endotoxin sensors.