Functionalised surfaces enable multi-faceted applications in biomedicine. For instance, they are needed to construct biosensors in which inorganic and organic components are in direct contact. They can quickly "recognise" certain substances in a sample in a targeted manner.
An inorganic surface can be coated with biomolecules, such as enzymes or alcohols. As enzymes are highly specific and only react with selected substances, this method is well suited for demonstrating the presence of certain substances. This technology is in everyday use even today, such as in the blood glucose test strips for diabetics.
Despite the potential of this technology, it is still in the initial stage of development. Research into functionalised surfaces must be improved if good sensors of this type are to be built. New methods need to be developed for this purpose, which enable things like the structure, functionality, stability and the interplay between the sample and the surrounding medium to be examined in de¬tail, without having to destroy the sample beforehand.
An alternative approach is based on surface plasmon resonance (SPR). This is a new method developed at ISAS to demonstrate the presence of individual viruses or other nanoparticles in their natural environment. Each nanoparticle bonded to the sensor surface shows up in the image as a bright stain and can be observed directly. This technology can be used to develop rapid tests to identify certain viruses, for example, or to examine the air for nanoparticles. In addition, new methods to investigate processes of membrane transport in cells could be derived.