Design and fabrication of a platform for circulating tumor cells (CTCs) isolation and detection by MiRGD@NTA@Au-Fe₃O₄...

To enable simple and rapid detection of circulating tumor cells (CTCs), we developed a targeted colorimetric biosensor based on MiRGD-functionalized Fe₃O₄-PEI-Au nanoparticles conjugated with TGA and Ni⁺²-NTA (MiRGD@NTA@Au-Fe₃O₄ nanoparticles). The biosensor enables magnetic separation of target cells and visual signal generation through the peroxidase-mimicking activity of Au-Fe₃O₄ nanoparticles, using TMB as a substrate. Colorimetric signals were monitored at 650 nm and discerned by the naked eye. Spectral data and fluorescence microscopy confirmed the specific binding of MiRGD peptides to cancer cells, ensuring discrimination from non-cancerous cells. Under optimized conditions, the assay exhibited a linear response for MDA-MB-231 cells suspended in PBS in the range of 5-5000 cells/mL, with a limit of detection (LOD) 6 cell/mL. The biosensor also demonstrated robust performance in human blood samples, with LOD 8 cell/mL, confirming its applicability in complex biological environments. These results highlight MiRGD@NTA@Au-Fe₃O₄ nanoparticles as a promising platform for simple, rapid, and high-sensitivity detection of CTCs, offering potential for clinical diagnostics and personalized cancer monitoring.