In an effort to gain a deeper understanding in the natural and medical science, research has over the last decades been increasingly focused on studies of the interactions and organization of molecules. Such research will provide a deep understanding of how individual molecules 'work' in terms of simple chemical and physical laws, and it may eventually make it possible to design drugs that go into specific places in the body and cures or alleviate disease states without unwanted side effects. In order to obtain a more profound understanding, a wide range of different techniques are employed for the determination of structures on the nanometer length scale. These include techniques like X-ray crystallography and nuclear magnetic resonance (NMR) measurements. The application of crystallographic methods requires that the molecules form perfect crystalline structures. This can be relatively difficult to achieve for large molecular complexes.  Therefore other techniques such as NMR are used for structure determination of (relatively small) proteins in solution.

Small-Angle X-ray Scattering (SAXS) provides an alternative to the above mentioned techniques. SAXS can be used on systems that are partially disordered and. Thus, the technique does not require crystalline order and it can be used for determining the structure of particles in solution. These include polymers, proteins, virus and vaccine particles, organic and inorganic nano particles and larger molecular complexes. For proteins this means that they can be examined in an environment which closely resembles their natural environment. The structure and function of proteins are closely related. Hence, in order to understand how they function, it is crucial to know their spatial structure. Since, there is no special preparation, SAXS allows studying the development of systems over time, e.g. fibril and plaque formation of misfolded proteins in connection with serious widespread diseases such as Parkinson’s, Alzheimer’s and type-2 diabetes. It is also possible to follow the development of nano structures as a result of chemical reactions over time.

Professor Jan Skov Pedersen (iNANO and Department of Chemistry) has received the funding to install a new unique SAXS instrument. It will use a new type of X-ray source in which a 'jet' of liquid metal is used as the anode. Moreover, a new type of x-ray detector will also be used in combination with a new slit system, which is developed at Aarhus University by Professor Pedersen.  Altogether, this will provide a fully optimized and unique SAXS instrument, which will have an x-ray intensity that is about 100 times higher than what has been commercial available until recently. Hence, it will be possible to measure the development of time with a resolution of one second.  Until now such measurements l have only been possible at large synchrotron radiation facilities. The new SAXS instrument will be developed in collaboration with the German company Bruker AXS. 

About the equipment

A new type of x-ray source based on a thin jet of liquid metal will be used. This source is 10 times more powerful than the most powerful types of x-ray source that has been available until recently. The liquid metal is a good conductor of heat, and therefore a very high power may be deposited in the anode. The Danish foundation, Carlsbergfondet, has granted 1.600.000 DKK  to the new x-ray source.

The source will supply x-rays to a modern SAXS instrument. Home-developed slits will be used in the instrument. These are manufactured in cooperation with the Mechanical Workshop at the Department of Chemistry. The new x-ray source and apertures will provide a unique x-ray insensitivity and will give the best laboratory-based SAXS in the world, which is only surpassed by synchrotron-based instruments. In addition, a stopped-flow apparatus for rapid mixing of the samples, which change with time, will be purchased. The new equipment will make it possible to follow the kinetics of various processes with a time resolution of a few seconds.

The funding for the new SAXS instrument has been obtained from The Danish Council for Independent Research | Natural Sciences (FNU). FNU has granted 5.480.977 DKK.

Novo Nordisk Fonden has granted 340.000 DKK to an automatic sample changer. This will secure a very efficient use of the SAXS instrument.