silicon and 1-2-diphytanoylphosphatidylcholine

Nano-BLMs (black lipid membranes) suspending the pores of highly ordered porous silicon substrates have been proven useful for functional investigations of ion channel proteins by electrical readouts. With the aim to monitor the resistive behavior of nano-BLMs spatially resolved in a contact-free manner, we report here on the visualization of nano-BLMs by means of scanning ion conductance microscopy (SICM). Silicon surfaces with highly ordered pore arrays were coated with a gold layer and functionalized with octadecanethiol before a droplet of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) (2% w/v) dissolved in n-decane was applied. The topography of DPhPC membranes suspending the pores was stably imaged for hours without mechanical contact using SICM. This suggests that SICM provides a significant advantage over atomic force microscopy, where mechanical interactions occur that easily damage the suspended membranes. Dynamic processes such as spreading and rupturing of membranes were spatially and temporally resolved. Furthermore, SICM was used to individually manipulate membranes suspending single pores, thereby writing lithographic patterns into the lipid. The process of local membrane manipulation was correlated to a characteristic signature in the simultaneously recorded ion current. The results show that SICM is well-suited both for contact-free imaging of soft suspended membranes and for local membrane manipulation.

Topics: Alkanes; Cations; Chemistry; DNA; Electrodes; Equipment Design; Ions; Lipid Bilayers; Lipids; Membranes; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Phosphatidylcholines; Silicon; Synchrotrons

Tethered membranes have been proven during recent years to be a powerful and flexible biomimetic platform. We reported in a previous article on the design of a new architecture based on the self-assembly of a thiolipid on ultrasmooth gold substrates, which shows extremely good electrical sealing properties as well as functionality of a bilayer membrane. Here, we describe the synthesis of lipids for a more modular design and the adaptation of the linker part to silane chemistry. We were able to form a functional tethered bilayer lipid membrane with good electrical sealing properties covering a silicon oxide surface. We demonstrate the functional incorporation of the ion carrier valinomycin and of the ion channel gramicidin.

Topics: Biophysics; Electric Impedance; Electrochemistry; Gold; Gramicidin; Ion Channels; Ionophores; Ions; Lipid Bilayers; Lipids; Microscopy, Atomic Force; Models, Chemical; Phosphatidylcholines; Phytol; Protein Array Analysis; Silanes; Silicon; Silicon Dioxide; Spectrophotometry; Substrate Specificity; Temperature; Time Factors; Valinomycin