# Application of multi-channel magnetic particle immunofluorescent disc microfluidic chip for combined detection of antibodies against six common infectious diseases including visceral leishmaniasis in pastoral areas

## TL;DR

A new microfluidic chip was developed to detect antibodies for six infectious diseases commonly found in pastoral areas, offering a faster and more efficient alternative to traditional methods.

## Contribution

The chip enables simultaneous detection of six infectious diseases with high accuracy and precision, improving over existing methods in throughput and application scope.

## Key findings

- The chip achieved a coefficient of determination (R2) greater than 0.98 for all detection targets.
- The chip demonstrated a minimum limit of detection (LOD) of 0.6 μg/mL and precision with relative standard deviation (RSD) under 10%.
- Detection results were consistent with ELISA, with no cross-reactions observed.

## Abstract

This study aimed to develop a microfluidic chip for the simultaneous detection of specific antibodies against six common pathogens in pastoral areas. The specific detection targets include: visceral leishmaniasis (IgG against Leishmania soluble antigen, IgG against recombinant K39 antigen); cystic echinococcosis (IgG against Echinococcus granulosus antigen 5, IgG against Echinococcus granulosus antigen B); alveolar echinococcosis (IgG against Echinococcus multilocularis antigen 2, IgG against Echinococcus multilocularis antigen 18); brucellosis (IgG against Brucella lipopolysaccharide, IgM against Brucella lipopolysaccharide); Lyme disease (IgG against Borrelia burgdorferi, IgM against Borrelia burgdorferi); and Xinjiang hemorrhagic fever (virus-specific IgG, virus-specific IgM).

Based on magnetic particle immunofluorescence, a multi-channel disc microfluidic chip and reagents were designed. Parameters (antigen-antibody microsphere ratio, sample dilution) were optimized; fluid dynamics tests verified fluid operation feasibility. Serum samples from patients with the six diseases and healthy controls were used to detect target antibodies. The chip’s accuracy, dose-response curve (R2), limit of detection (LOD), precision, and specificity were evaluated. Bland-Altman analysis compared results with traditional ELISA to assess consistency.

The chip exhibited normal fluidic operation. Optimized reagents/samples enhanced utilization efficiency. For the six diseases, the detection accuracy met the requirements: the coefficient of determination (R2) for all indicators was greater than 0.98, the minimum limit of detection (LOD) among the 12 detection items was 0.6 μg/mL, the relative standard deviation (RSD) for precision was less than 10%, and no cross-reactions occurred. Bland-Altman consistency analysis showed that the differences in detection results met clinically acceptable standards, demonstrating good consistency with enzyme-linked immunosorbent assay (ELISA).

This chip exhibits stable fluid flow, low sample/reagent consumption, and excellent accuracy/precision/specificity. Its detection results are consistent with those of traditional methods, and it enables the simultaneous combined detection of the aforementioned six infectious diseases. Compared with the clinically used method (enzyme-linked immunosorbent assay, ELISA), this chip has greater advantages in application scenarios and comprehensive benefits; compared with existing disc-based microfluidic technologies, it holds superior advantages in terms of detection throughput and application objectives. It provides a rapid, sensitive, and specific technical tool for the acute-phase screening, disease course confirmation, infection staging, differentiation between bacterial and parasitic infections, and disease prognosis detection of multiple prevalent infectious diseases in pastoral areas.