Au@Pt DNA Nanomachine Coupled with Photonic Crystal Microchip Enables High-Fidelity and Portable miRNA Detection.

Although great headway has been made in 3D DNA nanomachines, built from DNA-functionalized gold nanoparticles (Au NPs), for sensitive miRNA detection in complex media, their stability, accessibility, and portability still need to be improved. To surmount these hurdles, we are the first to develop a new way to integrate a Au@Pt (Pt-coated Au NPs) DNA nanomachine with a photonic crystal (PC) microchip for accurate and portable miRNA detection. Leveraging Au@Pt, characterized by ultraslow ligand exchange rate, as the core of 3D DNA nanomachines endows Au@Pt DNA nanomachine superior stability and signal fidelity. Meanwhile, a PC microchip capable of fluorescence enhancement capability acts as a solid-phase sensor chip, enabling on-site and portable miRNA-21 detection by interfacing with a miniaturized UV lamp device and a smartphone equipped with color recognition software. This newly developed sensor exhibits a swift response to miRNA, remarkable stability, and robust resistance to biothiols, as well as a high sensitivity (LOD as low as 0.144 pM). Clinical validation demonstrates its excellent diagnostic accuracy (AUC = 1) in the detection of miRNA-21 in patient serum, providing a paradigm for on-site and portable miRNA detection in areas with limited resources and equipment.