A microfluidic device for blood plasma separation and fluorescence detection of biomarkers using acoustic microstreaming

Abstract

Human blood plasma contains numerous soluble, diffusible, and secreted biomarkers that are used for clinical diagnosis and prognosis of various diseases. However, the blood of some patients is hemolyzed rapidly due to the rupture of cell membranes and releases chemicals and biological molecules that yield false-positive fluorescence detection results due to autofluorescence. The standard method for plasma separation is centrifugation, which is difficult to be integrated with various methods for downstream biomarker detection. Herein, we report development of a novel microfluidic device that is integrated with multiple functionalities on a single disposable chip. Using the principle of bubble-induced acoustic microstreaming, we have tested whole blood controls spiked with fluorescently tagged antibodies to HIV-1 p24 protein and obtained ∼ 31.8 % plasma yield with 99.9 % plasma purity within five minutes. The separated plasma was then routed to an integrated micro-mixing chamber and mixed with HIV-1 p24 antigen conjugated beads (10 μm diameter). The bound p24 antigen-antibody complexes were captured by acoustic microstreaming and detected using a fluorescence microscope. These experiments demonstrated a detection limit of ∼17 pg/μL of p24 antibody in the plasma. The microfluidic device successfully separated plasma from the whole blood control using acoustic microstreaming and integrated with acoustic micro-pumping and micro-mixing for enrichment of biomarkers by mixing p24-bound beads with fluorescently tagged antibodies. The beads with antigen-antibody complexes were efficiently captured in a separate compartment for fluorescence microscopy and detection of biomarkers. Integration of multiple functionalities on a single disposable microfluidic chip can now facilitate rapid detection of biomarkers and be used for monitoring patients’ specimen in real time.