2.2.3. Preparation of Bilayer Lipid Membranes

Bilayer lipid membranes (BLMs) are prepared after Montal and Mueller [27,28] in BC-20A chamber (Eastern Scientific LLC, Rockville, MD, USA), consisting of two similar Teflon blocks, each one with volume 2 mL, designed to hold 0.025 mm thin Teflon film in between. Solvent-free membrane patch is generated across a hole in the Teflon film with diameter 100 µm following the procedure described in [27]. The first step consists in pre-painting each side of the hole with ~1 µL of 1 wt% hexadecane in pentane and allowing the solvent to evaporate for ~5 min. The next step consists in pipetting in each compartment 0.5 mL of the aqueous solution containing 1 mM NaCl for the control sample or 1 mM of NaCl and 200 mM of glucose, fructose or sucrose. Thereafter, 15 µL of freshly prepared membrane-forming lipid solution is spread on top of the buffer in both compartments in order to ensure the presence of several lipid layers on the air-water interphase. The gentle addition of 1.5 mL of the corresponding aqueous solution consequently in each part of the cuvette leads to the generation of POPC bilayer on the aperture of the Teflon partition between the two compartments [28]. The final control of membrane formation and quality is performed electrically [27]. EIS-FTT measurement is effectuated immediately afterward.
