Micromotor-assisted fluorescence detection of Hg2+ with bio-inspired AO–Mn2O3/γ-AlO(OH)

Abstract

Micromotors have held great promise for environmental treatment due to their unique self-propelled movement that can significantly accelerate the chemical process in solution. Herein, we have developed a new AO–Mn₂O₃/γ-AlO(OH) fluorescent micromotor using renewable and uniquely hollow kapok fibers as biological templates. The AO–Mn₂O₃/γ-AlO(OH) micromotor was powered by the asymmetric decomposition of hydrogen peroxide fuel catalyzed by Mn₂O₃, reaching a maximum speed of 139.6 μm s⁻¹ in 3% H₂O₂ solution. The micromotor revealed a markedly enhanced fluorescence effect compared to both pure AO solution and non-micromotor counterparts and exhibited excellent selectivity and sensitivity for Hg²⁺ detection. The detection range and limit for Hg²⁺ were 5 × 10⁻⁸–5 × 10⁻⁵ M and 2.25 × 10⁻⁸ M, respectively. The enhanced Hg²⁺ sensing benefited from the synergy of enhanced fluorescence via the inhibition of the dimerization of AO, fluorescence quenching induced by charge transfer and the enhanced contact between the micromotor and Hg²⁺ ions resulted from the self-propelled motion. This micromotor-assisted fluorescence detection idea provided a new strategy for the development of sensors with high sensitivity.