The laboratory for photonics of surfaces and interfaces

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In our modern world - with its highly sophisticated synthetic chemistry and pharmacy and the extraordinary developments in health sciences - monitoring of specific molecules is gaining an increasing importance. The detection of biological, pharmaceutical and chemical agents or the detection of sickness-fingerprinting proteins, enzymes and antigens in (cancer) patients needs to be carried out as specific and quickly as possible. Sometimes even on-line information is essential, e.g. during surgery or a synthesis routine in pharmaceutical production. A trend in this analytical research is miniaturisation and the use of surfaces instead of volume sensors. This will allow to place the "sensor" at critical positions, e.g. into tissue or a vessel of a patient. The proposed research focuses on three subjects. Firstly, the engineering of highly sensitive optical transducers will translate chemical information into a physically measurable quantity. Secondly, the design of optimised surfaces for chemical recognition reactions will allow for high specificity avoiding false positives. Thirdly, a new technology will be established to study cell-substrate interaction, e.g. for fostering implant technology. The surfaces of these optical transducers, waveguide devices and gold nanoparticles, carry a "film of light" during operation which detects changes in the ambient material. Molecules carrying a recognition site are immobilised on the sensor surface by chemical means. They are able to perform a recognition reaction if the fitting molecule is present in the ambient solution or air. The polarisation of light is also taken into account. Natural optically active proteins turn the polarisation direction of light. The turning power depends on the molecular intrinsic structure, as well as their biological function. A sensor will be developed detecting the molecular intrinsic structure of proteins, which are available only in minute amounts.