A novel fluorescence immunoassay based on two-time amplified fluorescence signal by hemin and magnetic nanoparticles for the detection of antigen

摘要

A novel, selective, and sensitive magnetic-mimetic enzyme fluorescence immunoassay method for antigen detection has been developed by taking advantage of a magnetic separation process and the amplification feature of the hemin label. This method is based on a twice amplified fluorescence signal. The signal is first amplified due to the ultrasmall size and the high surface-to-volume ratio of the silica-coated magnetite nanoparticles, which enable the nanoparticles to carry much more antibodies. Second, the mimetic enzyme (hemin) as a labeling reagent catalyzes the reaction of p-hydroxyphenyl acetic acid and H2O2 can further amplify the fluorescence signal. This protocol was also evaluated for a sandwich-type immunoassay of human IgG, and the calibration graph for human IgG was linear over the range of 0-100ng mL(-1) with a detection limit of 9.8ng mL(-1). This method can easily separate magnetic nanoparticles from the solution, which simplified the process and played a promising role for various applications in immunoassay.