Self-generated single-drop microextraction enhanced aggregation-induced emission strategy based on magnetic metal-organic framework for microRNA-21 detection

Lung cancer is one of the most common malignancies with low prevention efficiency and high mortality, so prevention and early detection are very important. In this work, we propose a magnetic metal-organic skeleton nanomaterial bound to biological nucleic acid chains in a spatially confined magnetic single-drop microextraction (SDME) system to enhance the aggregation-induced emission (AIE) effect for fluorescence detection of miRNA-21 associated with lung cancer. DNA/MOF network structure was formed, and loaded with an AIE material, 4',4''',4''''',4'''''''-(ethene-1,1,2,2-tetrayl) tetrakis-([1,1-biphenyl]-3-carboxylic acid) (H₄ETTC), by DNA amplification reaction. From a serum sample, the structure was then spontaneously collected, forming a single drop at the end of a magnetic rod in less than 10 s by utilizing a magnetic SDME process. In this self-generated single drop, the structure was aggregated and the fluorescence signal of H₄ETTC was enhanced. Direct detection by fluorescence spectrophotometry was enabled. The limit of detection of miRNA-21 was 0.194 fM, and the linear range of miRNA-21 was 1 fM to 100 nM, respectively. The method was applied to the fluorescence detection of miRNA in human serum samples. The relative recoveries were 98.4 %-104.5 %.