The novel magnetic method used to immobilize the primary antibody in96-well polystyrene plates was investigated to determine the pregnancy-associatedplasma protein-A (PAPP-A), one of the most important protein markers inpregnancy. The optimal conditions for the immobilization are 20 μL magneticnanoparticles (0.72 mg/mL), 2μL primary antibody (30 μg/mL), and a one-stepprocess. The reaction was implemented in 40 minutes and 30 ºC. The calibrationcurve was established and the linear range shows up to 2090 mU/L. The LOQ andLOD are 7.2 and 24.0 mU/L, respectively. The reaction is non-specific for otherpregnancy hormones such as hCG and aFP even at a high level. The Passing &Bablok regression showed the linear relationship and the agreement between newand reference methods, y = a (95% CI)x + b(95% CI), a = 1.00 (0.971 to 1.019), b= 22.07 (-73.104 to 117.244), R2 = 0.999, p<
0.001. The Bland-Altman plot alsoshowed the high concordant. The new method can be used to determine PAPP-A inthe serum sample with mild conditions, simple and time-saving reaction, highsensitivity and selectivity, and comparable results with the commercial method.The novel magnetic method used to immobilize the primary antibody in96-well polystyrene plates was investigated to determine the pregnancy-associatedplasma protein-A (PAPP-A), one of the most important protein markers inpregnancy. The optimal conditions for the immobilization are 20 μL magneticnanoparticles (0.72 mg/mL), 2μL primary antibody (30 μg/mL), and a one-stepprocess. The reaction was implemented in 40 minutes and 30 ºC. The calibrationcurve was established and the linear range shows up to 2090 mU/L. The LOQ andLOD are 7.2 and 24.0 mU/L, respectively. The reaction is non-specific for otherpregnancy hormones such as hCG and aFP even at a high level. The Passing &Bablok regression showed the linear relationship and the agreement between newand reference methods, y = a (95% CI)x + b(95% CI), a = 1.00 (0.971 to 1.019), b= 22.07 (-73.104 to 117.244), R2 = 0.999, p<
0.001. The Bland-Altman plot alsoshowed the high concordant. The new method can be used to determine PAPP-A inthe serum sample with mild conditions, simple and time-saving reaction, highsensitivity and selectivity, and comparable results with the commercial method.