Magnetic immunoassay for tumor clinical diagnosis based on rolling circular amplification (RCA) coupled with ICP-MS

Herein, we constructed magnetic immunoassay-based diagnostic platform for cancer biomarker of patient' s sample by coupling rolling circular amplification with ICP-MS. Tumor biomarker (alpha-fetoprotein, AFP, Carcinoembryonic antigen, CEA) from clinical sample was initially captured by biotinylated antibody functionalized on the surface of magnetic beads, and then recognized by a secondary antibody that linked with a RCA(Rolling Circular Amplification)-primer. Up addition of RCA-template and DNA polymerase, one single target recognition event can be converted into multiple predesigned DNA sequences. This specific sequence can be hybridized with DNA-conjugated AuNPs and form a DNA-AuNP complex for ICP-MS measurement. Under the optimal experimental parameters, this platform can detect AFP and CEA in 20% serum, as low as 2 pg/mL and 5 pg/mL, respectively, which rivalled ELISA. We anticipate this methodology for tumor biomarker detection can be used for clinical diagnosis in future.