Accelerating the peroxidase-like activity of MOF-818@au NPs for colorimetric/portable Raman dual-mode sensing of Alzheimer's disease-related miRNA

The development of a simple-yet-practical and accurate sensing strategy for rapid detection of Alzheimer's disease (AD)-related miRNA in biofluids holds great promise for early diagnosis and monitoring of AD. Herein, a colorimetric/portable Raman dual-mode nanoprobe was proposed for quantification of AD-related miRNA-574-5p in biological fluids. The MOF-818@Au NPs@ssDNA nanoprobe was prepared by step-by-step loading of gold nanoparticles (Au NPs) and ssDNA onto the surface of MOF-818. Strikingly, the adsorbed ssDNA was capable of greatly improving the intrinsic peroxidase-like activity of MOF-818@Au NPs. In the presence of miRNA-574-5p, the ssDNA onto MOF-818@Au NPs will specifically hybridized with miRNA-574-5p, resulting in the desorption of ssDNA from MOF-818@Au NPs and the decrease of nanoenzyme activity for H 2 O 2 -mediated TMB oxidation. Based on this feature, visualization and quantitative analysis of miRNA-574-5p can be successfully realized by observing and measuring changes in output colorimetric/Raman signal from blue TMB oxide (oxTMB) with portable Raman spectrometer. Experimental results demonstrated that the colorimetric/portable Raman dual-mode nanoprobe can be utilized for fast, sensitive and accurate detection of AD-related miRNA-574-5p in complex human serum samples, providing a universal, valuable and practical tool for AD biomarkers detection and AD early diagnosis.