DEVELOPMENT AND VALIDATION OF THE MAGNETIC IMMOBILIZATION TO DETERMINE PAPP-A IN HUMAN SERUM

The novel magnetic method used to immobilize the primary antibody in 96-well polystyrene plates was investigated to determine the pregnancy-associated plasma protein-A (PAPP-A), one of the most important protein markers in pregnancy. The optimal conditions for the immobilization are 20 μL magnetic nanoparticles (0.72 mg/mL), 2μL primary antibody (30 μg/mL) and one-step process. The total reaction time is 40 minutes 30 ºC. The calibration curve was established and the linear range shows upto 2090 mU/L. The LOQ and LOD are 7.2 and 24.0 mU/L, respectively. The reaction is non-specificity for other pregnancy hormones such as hCG and aFP even at a high level. The Passing & Bablok regression showed the linear relationship and the agreement between new and reference method, a = 1.00 (0.97 to 1.02), b = 22.07 (-73.10 to 117.24), R2 = 0.999, p<0.001. The Bland-Altman plot also showed the high concordant. The new method can be used to determine PAPP-A in the serum sample with mild conditions, simple and time-saving reaction, high sensitivity and selectivity and comparable results with the commercial method.