Interfacial-Assembled Bubble-Driven Asymmetric Nanomotors for Velocity-Signaled Immunoassay

Recently, micro/nanomotors (MNMs) capable of converting external energy into mechanical energy have received extensive interest owing to their simple preparation process and broad environmental adaptability. In this study, an asymmetric NH2-Fe-MIL-88B@SiO2@Pt (MSP) nanomotor was successfully synthesized via a selective interface assembly strategy. The nanomotor exhibited a typical asymmetric structure, with one side spindle-shaped NH2-Fe-MIL-88B and the other side spherical SiO2. Notably, this asymmetric nanomotor possessed excellent catalase (CAT)-like activity, which enabled it to efficiently catalyze the decomposition of hydrogen peroxide to generate oxygen bubbles as the driving force for autonomous movement. Finite element analysis (FEA) simulation results confirmed that the MSP nanomotors can induce an asymmetric oxygen concentration gradient in their surrounding environment, thereby achieving more efficient and stable autonomous movement. Furthermore, an immunosensor was constructed based on the movement performance of the MSP nanomotors for the specific detection of aflatoxin B1 (AFB1). To break through the reliance on large instruments, a small 3D-printed detection device compatible with a smartphone was further constructed, which integrated nanomotor motion observation and signal collection functions, thereby providing support for the miniaturization and portability. This study not only offers new perspectives into the rational fabrication of nanomotors but also expands promising potential in the field of point-of-care testing (POCT) technology.