An improved portable biosensing system based on enzymatic chemiluminescence and magnetic immunoassay for biological compound detection

In this paper, an improved portable biosensing system has been developed for biological compounds detection. The device is based on enzymatic chemiluminescence and magnetic immunoassay with a miniaturized flow injection module. The immunoassay procedure involved a sandwich format, in which the antigen in the sample was first captured by the immobilized primary antibody on the surface of the magnetic beads, and then recognized by the second antibody labeled with enzyme. 3-(2′-spiroadamantyl)-4-methoxy- 4-(3″-phosphoryloxy)-phenyl-1,2-dioxetane (AMPPD) as the substrate amplified the enzymatic signal for the biological compound measurement. The portable biosensing system was characterized in a series of experiments with cardiac troponin I (cTnI), a golden standard protein marker for diagnosis of myocardial infarction, as a biological substance measurement model. It provided a linear response range of cTnI from 0.1 to 50 ng mL−1 (R = 0.99). The coefficient of variation was 6.7% in the repeatability test (n = 6). The novel system has great potential applications in the rural and community hospitals and can be easily extended to a variety of protein compounds analysis.