Pillar[5]arene@AuNP-Functionalized, Magnetically-Propelled Helical Micromotors for On-The-Fly Electrochemical Biosensing of p53 DNA Sequence

Electrochemical biosensors have promising applications such as the detection of biomarkers for cancer diagnosis, but their performance is still limited by the passive diffusion of molecules. Due to the autonomous and steerable motion capabilities, magnetically-driven micromotors display the advantages of enhancing diffusion and micro-mixing. However, developing micromotor-enhanced electrochemical biosensors is still challenging. Herein, we report magnetically-driven helical PANI-Fe₃O₄@SP-HP5@AuNPs (PFSHA) micromotors, in which the combination of the micromotor technology and host–guest recognition strategy enables sensitive detection of p53 DNA. The micromotors are fabricated by integrating gold nanoparticle-stabilized pillar[5]arenes (HP5@AuNPs), polyaniline (PANI), and iron oxide (Fe₃O₄) nanoparticles onto Spirulina (SP). Under a rotating magnetic field, the micromotors exhibit steerable motility with an average speed of 21.7 µm/s. Consequently, the micromotor-functionalized electrochemical biosensors achieve high sensitivity and a detection limit of 0.66 pM towards p53 DNA, with a linear range from 1 pM to 100 µM. The advantages of the micromotors, including autonomous motion, micro-mixing, enhanced diffusion, and improved mass transfer, enable significant improvement in the performance of electrochemical biosensing. Therefore, integrating micromotor technology into sensing analysis paves a promising way to address the limitations of existing electrochemical biosensors, offering new solutions for advanced clinical diagnosis.