Glass coverslips (24×60 mm, #1.5 thickness, Epredia) were cleaned by sequential sonication in chloroform, acetone, and isopropanol for 15 minutes before drying with N 2 . Circular silicone spacers (ϕ9×2.5 mm thickness, Merck) were washed with the same protocol, dried under vacuum, and then placed on top of the cleaned coverslip to form a chambered coverslip (Fig. ). The reaction chamber was sealed with an additional coverslip (22×22 mm, Merck) which was cleaned using the same procedure. To prepare plasma-cleaned coverslips, the solvent-cleaned coverslips were treated with oxygen plasma for 6 minutes (Diener Electronic, Femto, Germany).