Dual‐Responsive MnO ₂ ‐Loaded Carbonaceous Nanobottle Motors Fabricated by Interfacial Superassembly for On‐The‐Fly MicroRNA Sensing

Diverse nanomotors with advanced motion manipulation have been proposed to revolutionize the way problems in many fields are solved. However, rational and controllable synthetic methods of multifunctional nanomotor are still limited. Herein, dual-responsive MnO₂-loaded carbonaceous nanobottle motors (MnO₂ NBMs) are developed through an interfacial superassembly strategy. Asymmetric carbonaceous nanobottles are first synthesized, and the reductive carbonaceous shell induces an oxidation-reduction reaction with KMnO₄ for in-situ growth of MnO₂ nanosheets, which enables the nanomotor to perform either self-diffusiophoretic or self-thermophoretic motion in response to H₂O₂ and near-infrared light, respectively. Inspired by bioaffinity sensing, the nanomotors are sequentially assembled with functional nanoparticles and hairpin DNA to construct swimming functional MnO₂ NBMs (MnO₂ FNBMs) probes. The probes can move around complex samples to improve target miRNA transport and accelerate receptor-target interaction. Coupling with the photocurrent-signal amplification, the self-assembly of photoelectrochemical (PEC) biosensors has been achieved for sensitive microRNA detection. Trace amounts of miRNA-155 can be quickly detected with a wide detection range (100 fM to 100 nM). Moreover, the direct detection of microRNA in tumor cell lysates by the biosensor is demonstrated. Given the merits of automation and miniaturization, the proposed strategy provides a promising method for fast and effective self-assembly of biosensors.