New method for surface modification of nanoporous aluminum oxide membranes using tetraether lipid

Coating the inner pore walls of nanoporous aluminum oxide membranes with ultra thin films of archaebacterial tetraether lipids (TEL) was performed to change the filtration characteristics. A new lipid coating technique combining UV/ozone preactivation and supporting ultrasound was used to provide covalent binding of cyanuric chloride activated tetraether lipids onto the inner pores of the membrane. To give evidence of the inner wall lipid coating we applied X-ray photoelectron spectroscopy (XPS), laser scanning microscopy (LSM), and scanning electron microscopy (SEM). The high temperature stability (up to more than 200 °C) of the thin tetraether lipid film was proved with thermogravimetric infrared spectroscopy (TG-FTIR) and allows sterilization of the coated membrane up to this temperature. The lipid layer lining the pore walls of the inorganic membrane drastically changes the filtration properties which was verified using fluorescent nanocrystals (Q-Dots).