Magnetic immunofluorescent microfluidic chips for rapid multi-parameter detection of serum antibodies to brucellosis...

Brucellosis and echinococcosis are highly prevalent in pastoral areas, and traditional detection methods are limited because they are labor intensive, time consuming, and can only detect single-pathogens. This study aims to develop a magneto-immunofluorescent microfluidic chip for the rapid and simultaneous detection of serum antibodies against both brucellosis and echinococcosis and verify the detection performance and clinical application potential of the chip.

In this study, a magneto-immunofluorescent microfluidic chip was designed, fabricated and optimized, with a focus on the conjugation ratios of Echinococcus/Brucella antigens/antibodies to microspheres and the binding ratios of samples to fluorescent microspheres. The 2D/3D structures of the chip were verified via computational fluid dynamics simulation, and the core detection performance of the chip (linear range, limit of detection (LOD), precision, and specificity) was validated using positive sera and reference materials. The detection consistency between the chip and the clinical enzyme-linked immunosorbent assay (ELISA) was evaluated by coincidence rate, Kappa test, and Bland-Altman analysis. The technical advantages and limitations of the chip were then summarized.

The chip stably and reliably detected eight target antibodies (AgB IgG, Ag5 IgG, Em2 IgG, Em18 IgG, LPS IgM, LPS IgG, OMP25 IgM, OPM25 IgG), with all key performance indicators meeting clinical requirements. It showed high consistency with ELISA: the positive and negative coincidence rates of all target antibodies exceeded 90%, Em18 IgG and LPS IgG achieved 100% positive coincidence rate, and Em18 IgG also had 100% negative coincidence rate; Kappa values ranged from 0.88 to 0.98 (far higher than the 0.75 threshold for good consistency), and more than 90% of samples fell within the 95% confidence interval in Bland-Altman analysis. Compared with ELISA, the chip had advantages of being a "one-chip multi-test", with low sample consumption, rapid detection, and simple operation, suitable for on-site screening in pastoral areas.

The magneto-immunofluorescent microfluidic chip developed in this study enables the rapid and simultaneous detection of antibodies against brucellosis and echinococcosis, featuring excellent detection performance and high consistency with the gold standard method. This chip is expected to provide critical technical support for the early diagnosis, epidemiological surveillance, and precise prevention and control of both brucellosis and echinococcosis, thereby improving public health and preventing economic losses in the animal husbandry industry in high-prevalence regions of these two diseases.