Preparation of SLB chamber

Supported lipid bilayer (SLB) was formed on hydrophilic supporting substrates. We used the vesicle fusion method to get SLBs in the flow chamber. We used a flow chamber consisting of a top slide glass, a Parafilm spacer (4 mm by 50 mm by 200 μm), and a bottom cover glass (both glasses are purchased from Paul Marienfeld GmbH & Co. KG, Germany). The inner volume of the flow chamber is ~40 μl. The top slide glass, which has inlet and outlet holes, and the bottom cover glass were cleaned by 10-min sonication in DIW and 10-min piranha etching in H₂SO₄/H₂O₂ (3:1) and were thoroughly rinsed with DIW. To prevent SLB formation on the top glass, we passivated the top slide glass with bovine serum albumin (BSA) (10 mg/ml) in 150 mM NaCl phosphate-buffered saline (1× PBS) for 30 min. The flow chamber was assembled by placing a double layer of Parafilm spacer between the two glasses and heat sealing at 105°C. Next, the SUV solution was diluted to 1 mg/ml in 1× PBS solution and sonicated additionally for 15 min. The SUV solution is injected into the flow chamber and incubated for 40 min to form a lipid bilayer on the bottom of the chamber. The flow chamber was gently washed by injection of DIW (200 μl, twice) and 1× PBS (200 μl, once) and passivated with BSA (30 μg/ml) in 1× PBS for 30 min. Streptavidin (40 nM) in 1× PBS was injected into the flow chamber and incubated for 90 min to modify biotinylated DOPE in SLBs. Last, the flow chamber was washed with 1× PBS (200 μl, twice) and modified with DNA-functionalized nanoparticles for further experiments.