A two-step centrifugal microfluidic platform for semi-automated IGRA detection of tuberculosis based on chemiluminescence.

Tuberculosis (TB) is one of the leading fatal infectious diseases globally. As recommended by the WHO, interferon-γ release assay (IGRA) is an important method for accurate and efficient TB diagnosis; however, it is limited to the central labs due to multiple assisting devices, tedious manual operations, and the need for well-trained personnel. We have developed an integrated semi-automated platform combining centrifugal microfluidic chips with chemiluminescence immunoassay (CLIA) for TB-IGRA detection. The platform consists of two cooperative centrifugal chips and a portable companion analyzer with two operation sites. The incubation chip adopts a two-step highly efficient RBC separation strategy with wax valves to ensure the efficient purification of plasma with IFN-γ after the 20-24 h fully on-chip incubation period. The detection chip enables automated, multiple, and sequential reagent discharging, physically enhanced mixing, flexible magnetic bead operation and dynamic chemiluminescence signal detection. Within the companion analyzer, both the incubation and detection chips can be operated on two different sites for different tasks at different steps, respectively. Experiments with different samples for different purposes were systematically conducted to evaluate the system's functionality. As a preliminary proof-of-concept, experimental results demonstrated that the proposed single-device system achieves parallel N/T/P detection on two cooperative chips. By successfully automating the complex workflow traditionally performed by multiple benchtop instruments, this platform enables more convenient, semi-automatic, 'sample-to-result' TB diagnosis than the conventional IGRA protocols.