Highly sensitive hydrolytic nanozyme–based sensors for colorimetric detection of aluminum ions

Hydrolytic nanozyme–based visual colorimetry has emerged as a promising strategy for the detection of aluminum ions. However, most studies focus on simulating the structure of natural enzymes while neglecting to regulate the rate of hydrolysis-related steps, leading to low enzyme-like activity for hydrolytic nanozymes. Herein, we constructed a ruthenium dioxide (RuO₂) in situ embedded cerium oxide (CeO₂) nanozyme (RuO₂/CeO₂) with a Lewis acid–base pair (Ce–O-Ru-OH), which can simulate the catalytic behavior of phosphatase (PPase) and can be quantitatively quenched by Al³⁺ to achieve accurate and sensitive Al³⁺ colorimetric sensing detection. The incorporation of Ru into CeO₂ nanorods accelerates the dissociation of H₂O, followed by subsequent combination of hydroxide species to Lewis acidic Ce–O sites. This synergistic effect facilitates substrate activation and significantly enhances the hydrolysis activity of the nanozyme. The results show that the RuO₂/CeO₂ nanozyme exhibits a limit of detection as low as 0.5 ng/mL. We also demonstrate their efficacy in detecting Al³⁺ in various practical food samples. This study offers novel insights into the advancement of highly sensitive hydrolytic nanozyme engineering for sensing applications.