Bead number effect in a digital microfluidic immunoassay
IVF (In Vitro Fertilization) technology is currently the main way to treat infertility. It mainly uses in vitro fertilization to combine sperm and eggs to form embryos,and then implant them back into the mother. The choice of embryos mainly depends on the type of embryo. According to the literature, embryonic growth factors such as IL-1β may be used to determine embryonic growth.
The magnetic bead type digital microfluidic immunoassay chip developed by our laboratory with a small number of magnetic beads and magnetic bead aggregation has the advantages of low sample volume, short reaction time and high detection sensitivity compared with traditional immunological measurement methods. Satisfy the detection of Human IL-1β in single embryo culture medium. However, the number of magnetic beads is not fixed at present, and the reproducibility of the measurement is unstable, which makes the coefficient of variation (CV value) of the immunoassay calibration line more than 10%.
In this research, the magnetic bead capture chip is developed to achieve the quantitative effect of magnetic bead in immunoassay, and try to compare and quantify 100 beads, 49 beads, and 25 beads. The results show that compared with the CV value of the calibration curve of the unquantified magnetic beads, the CV value of the magnetic beads after quantification has a significant decrease. When the concentration of quantified 100 magnetic beads is 1 pg/ml ~100 pg/ml, the CV value is all below 10%, 49 particles have a CV value of less than 10% when the concentration is above 10 pg/ml, and 25 particles have a CV value of less than 10% when the concentration is above 25 pg/ml. The other 25 magnetic beads are in the fluorescence aggregation measurement, the number of beads is too small and the magnetic force is not good enough. When the number of magnetic beads is greater than 500, the beads will be stuck between the upper and lower plates when they are gathered and cannot move. After the magnetic beads are quantified, the signal can measured when the concentration of the analyte is 0.1pg/ml. The reproducibility and accuracy of immunoassays have been further improved.