Sensitive detection of thyroid stimulating hormone by inkjet printed microchip with a double signal amplification strategy

An electrochemical immunosensor for sensitive detection of thyroid stimulating hormone (TSH) has been developed by using an inkjet printed microchip and based on a double signal amplification strategy using magnetic beads (MBs), alkaline phosphatase (ALP) and p-aminophenyl phosphate (pAPP) reaction. Differential pulse voltammetry (DPV), cyclic voltammogram (CV) and amperometric i–t curve (i–t) were employed to characterize the immunosensor. High sensitivity and good selectivity were observed. The detection linear range was from 0.01 μIU/mL to 10 μIU/mL, in which the peak currents increased along with the concentration. The detection limit was 0.005 μIU/mL at S/N = 3. The immunosensor was also applied for TSH detection in human serum with recoveries from 98.0% to 101.8% and relative standard deviations from 1.3% to 3.1%, demonstrating potential value in clinical diagnosis.