Development of Magnetic and Fluorescent Immune Sensors for the Detection of Alpha Fetoprotein

Alpha fetoprotein (AFP) is one of the most widely used tumor biomarkers with significant values in early diagnosis of liver cancer. We designed both magnetic and fluorescent immune sensors in this work and utilized them in the detection of AFP in solutions. For the magnetic immune sensor, the immunomagnetic beads were applied to replace the traditional solid support because the immunomagnetic beads had larger specific surface areas which ensured the sufficiency of the antibody-antigen reaction. With the help of magnetic response, the separation process could be achieved rapidly, which was time-saving and nondestructive. Horseradish Peroxidase (HRP) on the Ab(2) could catalyze the substrates to chromogenic products which could be tested with UV-Vis spectrophotometry. The method had a correlation in the range of 10 similar to 80 ng . mL(-1) with a detection limit of 3. 6 ng . mL(-1) For the fluorescent immune sensor, we considered the fluorescence of CdTe QDs to be the output signal, and at the same time, a signal amplification system was introduced by doping the CdTe QDs onto the surface of the silica nanospheres which were suitable as the carrier for their adjustable size and stable properties. The fluorescent intensity of CdTe QDs was tested to calculate the concentration of AFP. The method reached a detection limit of 4. 2 ng . mL(-1) with a linear range of 5 similar to 150 ng . mL(-1). It was shown that both the developed magnetic and fluorescent immune sensors had high sensitivity to detect the concentration of AFP in solutions.