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.