Aptamer-Based Dual-Functional Probe for Rapid and Specific Counting and Imaging of MCF‑7 Cells

Development of multimodal detection technologies for accurate diagnosis of cancer at early stages is in great demand. In this work, we report a novel approach using an aptamer-based dual-functional probe for rapid, sensitive, and specific counting and visualization of MCF-7 cells by inductively coupled plasma–mass spectrometry (ICP-MS) and fluorescence imaging. The probe consists of a recognition unit of aptamer to catch cancer cells specifically, a fluorescent dye (FAM) moiety for fluorescence resonance energy transfer (FRET)-based “off-on” fluorescence imaging as well as gold nanoparticles (Au NPs) tag for both ICP-MS quantification and fluorescence quenching. Due to the signal amplification effect and low spectral interference of Au NPs in ICP-MS, an excellent linearity and sensitivity were achieved. Accordingly, a limit of detection of 81 MCF-7 cells and a relative standard deviation of 5.6% (800 cells, n = 7) were obtained. The dynamic linear range was 2 × 10² to 1.2 × 10⁴ cells, and the recoveries in human whole blood were in the range of 98–110%. Overall, the established method provides quantitative and visualized information on MCF-7 cells with a simple and rapid process and paves the way for a promising strategy for biomedical research and clinical diagnostics.