Immunomagnetic separation combined with inductively coupled plasma mass spectrometry for the detection of tumor cells using gold nanoparticle labeling.

This work reports an efficient, specific, and sensitive immunoassay protocol for detection of tumor cells by using inductively coupled plasma mass spectrometry (ICP-MS) with two probes. Magnetic nanobeads modified with anti-CD3 were used as capture probes for efficient and fast magnetic separation of Jurkat T cells from a mixture of cells, and gold nanoparticles (Au NPs) conjugated with anti-CD2 were used as detection probes for ICP-MS measurement. The capture and detection probes target the Jurkat T cells with high affinity and specificity, while they do not target other CD2/CD3-negative cells such as 97L cells and A549 cells. On the basis of these results, we proposed a new immunoassay for specific detection of Jurkat T cells. The conditions for this immunoassay were carefully optimized, including the incubation time and temperature, the concentration of the labeling probe, and the elution conditions. Under the optimized conditions, the linear range of 300-30,000 and the limit of detection of 86 Jurkat T cells were obtained, and the relative standard deviation for seven replicate detection of Jurkat T cells was 5.2% (3000 Jurkat T cells). This method has numerous advantages, including ease of preparation, low sample consumption, and high sensitivity and selectivity. Importantly, the methodology could be extended to the simultaneous detection of other cells based on their cellular biomarkers.