To confirm the role of gravity on adsorption of liquid-like coacervates toward a given substrate, a BCA assay was applied to quantify the amount of liquid-like droplets adsorbed on the substrate. Specifically, glass substrates (R = 5 mm) sitting at the bottom (bottom surface) or floating on the solution surface (upper surface) in TLC-M solutions with different concentrations (0.2, 0.5, 1, and 2 mg/ml) were taken out at different time intervals. Glass substrates were treated with formic acid for 12 hours, and the treated solution was then freeze-dried. Then, collected protein samples from the glass substrates were redissolved in 500 μl of PBS. BCA reagent buffer (A:B, 50:1) was mixed with protein solutions at 8:1 and incubated at 37°C for 30 min. Each sample (200 μl) was added into a 96-well plate, and the absorption was measured at 562 nm. Diluted albumin (bovine serum albumin) solutions were applied as concentration standards. Data are presented in table S1.