ᐊ P4-52
Open Readings 2025 • P4-53
P4-54 ᐅ

EFFECT OF ELECTRODE POTENTIAL ON ELECTROCHEMICAL IMPEDANCE SPECTRA OF TETHERED-BILAYER LIPID MEMBRANES ON FLUORINE-DOPED TIN OXIDE

Narvydas Dėnas1, 2, Kipras Eigminas1, Aušra Valiūnienė1, 2

1 Vilnius university, Institute of Chemistry, Naugarduko str. 24, LT-03225, Vilnius, Lithuania

2 State Research Institute Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257

[email protected]

Tethered-bilayer lipid membranes (tBLMs) are membranes supported on a solid surface in which the inner layer of the lipid bilayer is covalently attached to the surface through a spacer group, which covers minor surface irregularities and forms an aqueous reservoir with the functional properties of the cytoplasm [1]. tBLMs can simulate cell membranes as accurately as possible and recreate the basic functions of cell membranes [2, 3].

tBLMs are suitable for the systematic study of different types of membrane-associated processes, provide the lipid environment needed to study membrane-associated proteins and can be used for biosensing applications [4]. Surface-sensitive techniques such as electrochemical impedance spectroscopy (EIS) are commonly used to study tBLMs and their interactions with proteins. However, the EIS response of tBLMs on the gold surface is strongly dependent on the potential, so a three-electrode system must be used for measurements [5]. Furthermore, EIS signal on gold surface highly depends on the composition of the tBLMs spacer group [6]. The problems mentioned above lead to some difficulties in the practical application of tBLM-based sensors on gold surfaces. Metal oxide substrates, such as fluorine-doped tin oxide (FTO) or others, can offer significant advantages as solid supports due to their lower fabrication cost and strong Si-MeO covalent bond, which avoids clustering of molecular anchors and provides regeneration capabilities [7].

In this work, tBLMs were formed on FTO-coated glass surfaces using different compositions of molecular anchors and EIS measurements were performed to determine the sensitivity of tBLM-based sensors to pore-forming toxin at different electrode potentials. The potential range used for the measurements was 0V to 1V vs Ag|AgCl, KCl\(_{sat.}\) which is the ideal polarisation range of the system under investigation. The tBLM-based sensors on the FTO surface were investigated using fast Fourier Transform Electrochemical Impedance Spectroscopy (FFT-EIS), which allows a single EIS spectrum to be obtained in  3 s in the frequency range from 0.2 Hz to 10 kHz.

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[5] V. Liustrovaitė, A. Valiūnienė, G. Valinčius, and A. Ramanavičius, “Electrochemical Impedance Spectroscopy Based Evaluation of Chlorophyll a Reconstitution within Tethered Bilayer Lipid Membrane,” J Electrochem Soc, vol. 168, no. 6, p. 066506, Jun. 2021, doi: 10.1149/1945-7111/AC0262.

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[7] I. Gabriunaite, A. Valiūnienė, and G. Valincius, “Formation and properties of phospholipid bilayers on fluorine doped tin oxide electrodes,” Electrochim Acta, vol. 283, pp. 1351–1358, Sep. 2018, doi: 10.1016/J.ELECTACTA.2018.04.160.