Mechanically Polished Titanium Surface for Immobilization of Hybrid Bilayer Membrane

Abstract

In this work, hybrid bilayer lipid membrane (hBLM) was assembled on a mechanically polished metallurgical titanium plate. Hydrophobic molecular anchors needed for phospholipid overlayers were obtained by silanization of the Ti surface with octadecyltrichlorosilane (OTS). The formation of hBLM was accomplished by fusion of the multilamellar vesicles containing of 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol (Chol) at molar % ratio 60/40. The fusion process was monitored in real-time by the dynamic fast Fourier transformation (FFT) electrochemical impedance spectroscopy. We found that the repetitive regeneration of hBLM can be performed up to 4 times with no major loss of the electrochemical properties. Also, we showed that the electric barrier function of hBLMs is disrupted by phospholipase A 2 (PLA2) -an enzyme, which hydrolyzes the fatty acid bonds at sn2 position in membrane phospholipids. Such effect may be used to design biosensors sensitive to both concentration and activity of the membrane damaging proteins, and possibly other agents.

Hybrid bilayer membranes on metallurgical polished aluminum

“…After the silanization procedure, the values of contact angles increased to 105.13° ± 2.02° clearly demonstrating hydrophobic properties of the silanized Al surface. The obtained contact angle values of 105.13° ± 2.02° for the silanized Al surface are slightly higher than those obtained on OTS monolayer formed on mechanically polished Ti surface (102.27° ± 1.76°) 41 and lower than those obtained on OTS formed on FTO (119° ± 7°) 38 surface. However, the change of the wetting characteristics from hydrophilic to hydrophobic in all cases attests for the formation of the organic OTS monolayer on the surface, and consequently shows that functionalized metallurgical aluminum surface has sufficient surface free energy, needed for further immobilization of phospholipid layer 62 .…”

“…EIS, which is capable of detecting the dielectric properties of the surface, was applied for investigation of the hybrid bilayer formation on the metallurgical aluminum surface. Typically, the semi-circular shape of EI response in the complex capacitance plot is observed for ideally polarizable interfaces demonstrating nearly ideal capacitive behavior 26 , 34 , 41 , 68 . The approximate complex capacitance values can be obtained from the Cole–Cole plots by taking the radius of the semi-circle and multiplying it by two.…”

“…The difference in the capacitance values is an indication of void spaces (defects) in the SAM exposing the Al surface and, consequently, these defects increase the complex capacitance of the SAM 70 . Taking into account that OTS silanized mechanically polished titanium 41 and magnetron sputtered titanium 40 surfaces were successfully applied for the formation of hBLMs albeit exhibiting complex capacitance values above 1 µF cm −2 , the silanized metallurgical Al surface was also tested for the formation of bilayer lipid membranes via vesicle fusion. After immobilization of hBLMs, the complex capacitances decreased to 0.61 µF cm −2 ± 0.07 µF cm −2 (Fig.…”

“…Therefore, the magnitude of the literature clearly indicates metallurgical surfaces have extensive potential to be used as membrane-based biosensor platforms. Previously, we investigated metallurgical titanium surface for the phospholipid bilayer formation 41 , 42 , since titanium exhibits excellent biocompatibility, high chemical stability, and non-toxicity 47 . Nevertheless, preparation of metallurgical titanium surface e.g.…”

Investigation of Active and Inactivated Yeast Cells by Scanning Electrochemical Impedance Microscopy

“…Meanwhile, EIS is a non-destructive method, which is providing useful models on the effect of alternating current (AC) on the sample. EIS enables registering quantitative data, which determines properties of electrode/electrolyte boundary [2,[28][29][30][31]. However, conventional EIS-based technique has a problem because it represents only average response of a whole electrochemical system.…”