**4. Conclusions**

− In this work, we have evaluated the properties of the lipid membranes obtained by adsorption of bicelles on thioglucose-modifed gold electrodes. We have demonstrated that adsorption of bicelles occurs by the replacement of the interfacial water. Their spontaneous deposition leads to the formation of a double bilayer structure on the electrode surface. However, the resulting lipid assembly contains numerous defects and pinholes which span either the entire thickness of the film or only the top bilayer. This in turn, affects the electrochemical properties of the membrane, which was found to be permeable for ions and water. Significant improvement in terms of the morphology of the lipid film and its electrochemical characteristics is achieved upon freeze–thaw treatment. The number of pinholes and defect sites is reduced, and the lipid assembly is rearranged to a single bilayer configuration with locally occurring patches of the second bilayer on top of it. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced. The latter is manifested by the relatively high value of the membrane resistance of ~1 MΩ cm<sup>2</sup> . We believe that the approach presented in this work offers an alternative way to obtain stable planar lipid membranes with good insulating properties. In perspective, the benefit of such an approach is that bicelles are known to be a suitable lipid environment for reconstitution and studies of the transmembrane proteins. Hence, more complex cell membrane mimics can be obtained by depositing bicellar mixtures on electrodes.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/2077-037 5/11/1/11/s1, Figure S1: AFM image of a bare Au(111) electrode collected in an aqueous solution of 0.1 M NaF. The image was taken in PeakForce Tapping mode. Figure S2: AFM image and crosssectional profile of the ripple phase. The image was collected in an aqueous solution of 0.1 M NaF using PeakForce Tapping mode.

**Author Contributions:** Conceptualization, D.D. and S.S.; Formal analysis, S.S.; Investigation, D.D.; Methodology, K.S. and S.S.; Resources, K.S.; Writing—original draft, D.D.; Writing—review & editing, S.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Polish National Science Centre, Project No. 2016/21/B/ST4/ 02122.

**Acknowledgments:** The study was carried out at the Biological and Chemical Research Centre, University of Warsaw, established within the project co-financed by European Union from the European Regional Development Fund under the Operational Program Innovative Economy, 2007–2013.

**Conflicts of Interest:** The authors declare no conflict of interest.
