Colorimetric Detection of Met Dimerization on Live Cells via Smartphone for High-Sensitivity Sensing of the HGF/Met Signaling Pathway

Membrane protein dimerization regulates numerous cellular biological processes; therefore, highly sensitive and facile detection of membrane protein dimerization are very crucial for clinical diagnosis and biomedical research. Herein, a colorimetric detection of Met dimerization on live cells via smartphone for high-sensitivity sensing of the HGF/Met signaling pathway was developed for the first time. The Met monomers on live cells were recognized by specific ligands (aptamers) first, and the Met dimerizations triggered the proximity-ligation-assisted catalytic hairpin assembly (CHA) reaction to generate large amounts of Gquadruplex (G4) fragments which can further combine hemin to form G4/hemin DNAzymes possessing the horseradish-peroxidase-like catalytic activity for catalyzing the oxidation of ABTS by H2O2 and producing the colorimetric signal (i.e., color change). The colorimetric detection of Met on live cells was then achieved by image acquisition and processing via a smartphone. As a proof-of-principle, the HGF/Met signaling pathway based on Met-Met dimerization was facile monitored, and the human gastric cancer cells MKN-45 with natural Met-Met dimers were sensitively tested and a wide linear working range from 2 to 1000 cells with a low detection limit of 1 cell was obtained. The colorimetric assay possesses a good specificity and high recovery rate of MKN-45 cells spiked in peripheral blood, which indicates that the proposed colorimetric detection of Met dimerization can be used for convenient observation of the HGF/ Met signaling pathway and has extensive application prospects in point-of-care testing (POCT) of Met-dimerization-related tumor cells.

Automated summary

This study developed a smartphone-based colorimetric detection method for Met dimerization on live cells, enabling high-sensitivity sensing of the HGF/Met signaling pathway. Met monomers on live cells were recognized by specific ligands, triggering a catalytic reaction to generate G-quadruplex fragments, which could further combine with hemin to form DNAzymes with catalytic activity. These DNAzymes produced a colorimetric signal upon catalyzing the oxidation of ABTS. The colorimetric assay was achieved through image acquisition and processing on a smartphone. The proposed method demonstrated a wide linear working range and low detection limit, making it suitable for point-of-care testing of Met-dimerization-related tumor cells.