Fusion 5 membrane

The HYPER pad has three layers: a differentiation pad, a filtration membrane and a calibration pad. The differentiation pad was made from FR-01 (0.35 mm) horizontal blood filtration pad (Advance Microdevice Pvt. Ltd.). The filtration membrane was an Asymmetric Polysulfone based Vivid Plasma GF Separation Membrane (PALL, Inc.), which serves as the primary blood cell filter. The calibration pad was a Fusion 5 membrane (GE Health) which have 40 μL/cm2 wicking capacity. To manufacture HYPER pad, first FR-01 pad, GF membrane were cut to 12 mm and 8 mm wide strips respectively, and then the two membranes were attached to a piece of plastic tape with a 7 mm overlap. The Fusion 5 membrane was cut to the desired width according to the correlation between the length of calibration pad and the outflow serum volume, and then attached underneath the GF membrane with a 7 mm overlap. For HYPER pads that were integrated into lateral flow assay, they were used as sample pad on the test strips. Otherwise the HYPER pad was then cut into 4 mm wide pieces for blood separation and serum collection. More detailed fabrication method is included in the supplementary information.

Figure 3 depicts the schematic of the aptamer-phage LFA. Polyclonal anti-human IgE rabbit serum (Fitzgerald Industries International, Acton, MA; 5 μl, diluted 100-fold in 50 mM sodium acetate buffer (pH 3.6) based on preliminary screening experiments) and 5 μL of rabbit polyclonal anti-M13 IgG antibodies (Novus Biologicals, Littleton, CO; 0.1 μg/μL in 50 mM sodium acetate buffer (pH 3.6)) were used to make test and control lines respectively on Fusion 5 membranes (GE Healthcare, Piscataway, NJ) using a Lateral Flow Reagent Dispenser (Claremont BioSolutions, Upland, CA) equipped with an external syringe pump (Chemyx, Stafford, TX). The Fusion 5 membrane was cut into 7 mm × 50 mm strips using a guillotine paper cutter. CF5 membrane (GE Healthcare) was used as the absorbent pad (7 mm × 25 mm) and Fusion 5 membrane (7 mm × 10 mm) was used as a sample pad. The strips were allowed to dry for 1 hr at 25 °C before use.