Functional Nucleic Acid-Based Magnetic Nanomachine-Driven Lateral Flow Strip for Highly Sensitive Detection of Colorectal Cancer Biomarker miR-141

This study reports the development of a rapid and highly sensitive lateral flow strip incorporating functional nucleic acid–based magnetic nanomachines for the detection of the colorectal cancer biomarker miR-141. The nanomachines were constructed by immobilizing two designed sequences, a DNA walker and a hairpin probe (HP1), onto gold-coated magnetic beads. To prevent nonspecific activation, the DNA walker was initially blocked by a short complementary strand, which was displaced upon specific recognition of miR-141. The released DNA walker subsequently hybridized with HP1, initiating nicking reactions that generated abundant DNA fragments. The reaction mixture was then applied onto the lateral flow strip, while the magnetic nanomachines were rapidly removed by an external magnet positioned beneath the sample pad to eliminate interference. The DNA fragments produced were further captured by two reporter probes labeled with FITC and biotin, forming a sandwich complex that bound to anti-FITC antibodies immobilized on the test line. The accumulation of streptavidin-modified gold nanoparticles on this complex generated a distinct visual signal observable by the naked eye.
This study presents a novel magnetic nanomachine–integrated lateral flow strip that offers significantly improved sensitivity compared to conventional lateral flow strips. By applying an external magnetic field, the magnetic nanomachines can be rapidly and conveniently separated, enabling the development of a user-friendly platform that achieves both rapid and highly sensitive detection. Furthermore, the detection versatility of this system can be readily extended by simply modifying the sequences on the magnetic nanomachines, allowing adaptation to a wide range of targets. This flexibility highlights the potential of the proposed method as a universal platform for rapid diagnostics, greatly enhancing its commercial applicability and translational value in point-of-care testing.