In an article at The Age about Aussie nano-technology, we read about a Sydney-based medical diagnostics group Ambri. The company has designed a biosensor that converts a biological binding event into a digital electrical signal. This enables the biosensor to employ computer technology to analyse and define this biological event.
Some basic info about the technology:
The AMBRI™ Ion Channel Switch™ (ICS™) Sensor is one of the world’s first true bionanotechnology devices. A self-assembling, synthetic, two molecular layer bio-membrane, the ICS™ acts like a biological switch and is capable of detecting a range of biological and chemical substances such as drugs, hormones, bacteria, DNA, and ions, in any body fluid, including whole blood, urine, and saliva. The biological switch is triggered when a molecule binds to an antibody fragment, this changes the number of conducting ion channel pairs within the membrane, which in turn, alters the way the membrane conducts. The resulting change in ion flow is measured by Ambri’s sophisticated technology and analytical software as a variation in current which determines the identity of the molecular material under investigation. The technology is built on the nanometer scale, using molecular components one-thousand-millionth of a meter in size. Ambri’s ICS™ Technology mimics biological sensory functions and can be used with most types of receptor, including antibodies and nucleotides. The sensor is essentially an impedance element whose dimensions can readily be reduced to become an integral component of a microelectronic circuit.
Ambri has built a biological switch: a membrane which can detect the presence of specific molecules and signal their presence by triggering an electrical current. This device — the Ambri Ion Channel Switch(ICS™) Biosensor — is a two molecular layer self assembled membrane based on the ion channel gramicidin.
The diagram shows the various components of the AMBRI® Biosensor — the molecule to be detected, the antibody fragments, the linker protein steptavidin and biotin linkers, the membrane layers with included gramicidin molecules.
The AMBRI® biosensor operates as a synthetic mimic of a nerve cell membrane.
The key elements in this artificial membrane are:
— membrane forming molecules chemically tethered to a surface
— simple ion channels within the membrane which facilitate the transport of ions like sodium
–an ionically conducting reservoir space between the electronically conductive gold surface and the membrane to store ions when they have crossed the membrane.
— receptors such as antibodies attached to the membrane to recognise target molecules.