All-in-one microfluidic immunosensing device for rapid and end-to-end determination of salivary biomarkers of cardiovascular diseases

Routine screening for cardiovascular diseases (CVDs) through point-of-care assays for at-home or community-based testing of salivary biomarkers can significantly improve patient outcomes. However, its translatability has been hindered by a dearth of biosensing devices that streamline assay procedures for rapid biomarker quantitation. To address this challenge through end-to-end engineering, we developed an in-house, all-in-one microfluidic immunosensing device that integrates on-chip vibration-enhanced incubation, magnetic-assisted separation using immune magnetic bead probes, and colorimetric readout via absorbance measurements. This device enables probe preparation and one-pot immunoassay procedures on a reusable microfluidic chip. By engaging the vibrator with the reaction chamber, the vibration-enhanced incubation module significantly accelerates immune complex formation, drastically reducing the sample-to-answer timeline of approximately 1 h required for room temperature enzyme-linked immunosorbent assay (ELISA) to just under 15 min. We showcase the utility of the device with an on-demand assay for a biomarker panel comprising C-reactive protein (CRP), interleukin 6 (IL-6), and procalcitonin (PCT). The device achieved a linear detection range of 1.75-28 ng mL^-1 for CRP and 1.56-100 ng mL^-1 for IL-6 and PCT with an R² > 0.98 for all three biomarkers. The limits of detection were 0.295, 0.400, and 0.947 ng mL^-1, respectively. Results from real saliva samples were consistent with standard ELISA (R² = 0.952). This fully integrated, modular immunosensing device opens up opportunities for household CVD screening and could be adapted for rapid, affordable multiplexed biosensing for other major chronic diseases at the point of care.