Researchers have developed a new method to produce artificial membranes: Using a nanoscaled tip, they write tailored patches of phospholipid membrane onto a graphene substrate. The resulting biomimetic membranes, i.e. membranes simulating biological structures, allow for the specific investigation of functions of cell membranes and the development of novel applications in medicine and biotechnology, such as biosensors.

Lipids (from Greek lipos, “fat”) are central structural elements of cell membranes. The human body contains about 100 trillion cells, each of which is enveloped in a cell membrane which essentially is a double layer of partly hydrophilic, partly hydrophobic phosphorus-containing lipids. These cell membranes contain numerous proteins, ion channels, and other biomolecules, each performing vital functions. It is therefore important to study cell membranes for many areas of medicine and biotechnology. Better understanding of their functions will open up novel applications, such as sensors with biological components, use of enzymes as catalysts, or specific introduction of medical substances. However, it is very difficult to study the membranes directly in live cells inside the human body.

Consequently, researchers frequently use model membranes that are applied to special surfaces. These biomimetic systems, i.e. systems simulating biological structures, are more convenient and can be controlled much better. An international group of researchers now presents a new method to produce biomimetic membranes: They write tailored patches of phospholipid membrane onto a graphene substrate by means of lipid dip-pen nanolithography (L-DPN), a method developed at KIT.

The graphene that is used as a substrate is a semi-metal with unique electronic properties. According to Dr. Aravin Vijayaraghavan from the University of Manchester, the lipids applied onto graphene spread uniformly, thus forming high-quality membranes. Other advantages of graphene are its tunable conductivity and its property to quench fluorescence of labeled phospholipids. When the lipids contain the corresponding binding sites, such as biotin, the membranes actively bind streptavidin, a protein produced by certain bacteria and used in various biotechnological methods. When the lipids are charged, charge is transferred from the lipids into graphene. This changes the conductivity of graphene, which may be used as a detection signal in biosensors.

The researchers will use their biomimetic membranes in the future to construct novel biosensors based on graphene and lipids. It is planned to design sensors that react to the binding of proteins by a change of conductivity as well as sensors detecting the function of ion channels in membranes. Ion channels are pore-forming proteins via which electrically charged particles can cross the membrane. “Protein sensors might be applied in medical diagnostics. Controlling the function of ion channels is important in drug research,” the KIT scientist says.

This story is reprinted from material from
Karlsruhe Institute of Technology, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.