Minimalist digital microfluidics for high-performance multiplexed protein POCT: A wash-free, sample-to-answer, and
Zhuoru Li1, Haibo Zhang2, Qingsheng Guo1
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China.
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High-performance protein point-of-care testing (POCT) has become a critical clinical need, particularly for rapid decision-making in acute settings. However, current protein POCT technologies, such as lateral flow assays and electrochemical sensors, struggle to simultaneously achieve high sensitivity, operational simplicity, and robustness. In this work, an integrated digital microfluidic platform for multiplexed luminescence oxygen channeling immunoassay (iDMF-mLOCI) is developed, leveraging precise droplet manipulation on DMF to create a wash-free, multiplexed suspension assay for protein POCT. This system uniquely features: (1) Fast on-chip plasma separation (<30 s); (2) No washing cycles (100% bead retention, 23% faster processing versus conventional DMF immunoassays) and (3) High reproducibility (coefficient of variations (CVs) < 9.1%). These advancements enable sensitive multiplexed detection of protein biomarkers (Limits of detection (LODs): 2.2 pg/mL for interleukin-6 (IL-6), 0.05 ng/mL for procalcitonin (PCT), 0.2 ng/mL for heparin-binding protein (HBP)) using only 2.2 μL of trace sample per test. Utilizing the established iDMF-mLOCI platform, diagnostic capability for sepsis is assessed, which demonstrates excellent diagnostic accuracy (area under curve (AUC) = 0.934) and strong correlation with clinical widely used central laboratory testing methods (coefficient of determination (R2) > 0.94). This work defines and demonstrates a transformative sample-to-answer paradigm, seamlessly integrating simplicity, multiplexing, sensitivity, and precision, thereby advancing the frontier of high-performance POCT diagnostics for critical care.
