Elemental-tagged immunoassay combined with inductively coupled plasma mass spectrometry for the detection of tumor cells using a lead sulfide nanoparticle label

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 lead sulfide nanoparticles (PbS NPs) as the elemental tags. PbS NPs conjugated with anti-EpCAM target the HepG2 cells with high affinity and specificity. The conditions of the ICP-MS based immunoassay for the detection of HepG2 cells were carefully optimized, including the incubation time, the concentration of the labeling probe, and the elution conditions. Under the optimized conditions, the limit of detection of 282 HepG2 cells and the linear range of 800-40,000 were obtained, and the relative standard deviation for seven replicate determinations of 3000 HepG2 cells was 5.0%. The proposed method has numerous advantages, including ease of preparation, high sensitivity and selectivity. Importantly, this methodology could be extended to the detection of other cells based on their cellular biomarkers.