The work group deals with the surface structure analysis of chemical and biological biopolymers on the nanometre scale, in particular with protein structures and viruses. This application of TERS (tip-enhanced Raman Spectroscopy) is closely related to the optimisation of suitable measuring probes, required for a simultaneous topographic and chemical characterisation. By using different evaluation methods it is possible to generate an image of the analysed sample surface based on the collected data. This way it is feasible to distinguish molecular domains or to image the distribution of different chemical components.
The aim is a fast and efficient analysis of viruses based on single particles using TERS in close cooperation with the research department Spectroscopy / Imaging. Conventional methods for virus identification need a lot of viral material ,which is obtained by time consuming cell culture methods. However, a fast virus detection is generally of interest. A structure determination and, thus, a differentiation of viruses on the nanometre scale is possible with TERS. In this process a much smaller sample amount is needed. An important step is the specific sample preparation and the immobilisation on suitable substrates, respectively. In the actual near-field Raman measurements topographic and chemical information of single virus surfaces are collected. First successful studies have demonstrated the possibility to differentiate virus strains. In the future more complex samples, i.e. “similar” viruses will be analysed. Therefore, data evaluation methods have to be developed further for achieving fast and reliable assignments.
In fact, the phenomena of fibrillation of proteins is sufficiently known, but the growth mechanism has not been elucidated so far. Pathogenic deposits from amyloid structures can cause an irreversible damage on cells and tissues and furthermore trigger diseases such as Alzheimer disease and Parkinson disease.
Whereas standard biological and spectroscopic characterisation methods provide averaged information on the whole sample volume, TERS is able to analyse single amyloid fibrils and particularly, the actual important surface structure. The main focus is the identification of the secondary structure - a valuable indicator for the formation of amyloid structure . Standard Raman Spectroscopy and TERS complement each other in this case, since Raman provides information on the core composition and TERS specifically characterises the fibril surface. The secondary structures of fibril-core and -surface differ clearly: the former contains regularly arranged protein chains, whereas the latter consists of mixed structures. This knowledge could contribute to a better chemical understanding of amyloid fibrils and promote the future development of suitable anti fibril reagents.