Many organic molecules are delivered to us in crystalline form, ranging from foodstuffs such as the cocoa butter in chocolate, to pigments, propellants, and pharmaceuticals. Organic molecules can adopt a range of crystalline forms, or polymorphs, that have distinct properties, including melting temperature, colour, detonation sensitivity, and dissolution rate. This proposal will develop new ways of predicting and producing an extended range of polymorphic forms for a given molecule. Even when the molecule is not delivered in a crystalline form, a detailed understanding of its crystallisation behaviour is necessary for optimising the manufacturing process, and designing the product to prevent crystals forming (e.g. ruining a liquid crystal display). A major risk in the manufacture of organic products is the unanticipated appearance of an alternative polymorph, as resulted in the withdrawal and reformulation of the HIV medicine ritonavir, and of transdermal patches of a Parkinson's disease treatment that became unreliable once rotigotine re-crystallised unexpectedly on storage. Crystallisation is a two-stage process comprising nucleation (formation of stable clusters of molecules) and growth (growth of clusters until visible crystals are observed). The appearance of many polymorphs late in product development has been attributed to difficulties in nucleating the first crystals. However, changes in the impurity molecules present and contact with different surfaces may catalyse this nucleation. In this proposal we will explore the influence different chemical and physical surfaces have on nucleation of new polymorphs. Although many thousands of crystallisation experiments can be performed in developing a new product, this is costly and time consuming and it is impractical to test all possible conditions. Thus the ability to select specific predicted forms and design experiments to enable these forms to nucleate for the first time turns polymorphism into an advantage in product and process design. It would allow crystal forms to be selected and manufactured with the particular properties best suited to the intended application of the molecule. The research will also provide a deeper understanding of the true range of solid-state diversity that an organic molecule can display. The EPSRC Basic Technology program has funded "Control and Prediction of the Organic Solid State" which has established an internationally unique capability of predicting the range of thermodynamically feasible polymorphs for a given molecule. This project has demonstrated the capability to produce the first crystals of a distinctive new polymorph of a heavily studied anti-epileptic drug, by crystallising it from the vapour onto a computationally inspired choice of a suitable template crystal of a related molecule. This finding proves that totally new forms can be discovered using templates designed to target a particular computationally predicted polymorph. However, it is essential to understand the interplay between structure, surface, kinetics and thermodynamics in directing this process if we are to harness the underpinning science for wider applications. This interdisciplinary project seeks to establish the fundamental relationship between the predicted polymorph and the heterogeneous surface which promotes its formation. We will develop a range of methods for prediction and selection of likely polymorphs as well as novel crystallisation experiments and technologies, including inkjet printing. The detailed molecular level characterisation of how one crystal structure grows off another will produce a fundamental understanding of this phenomenon, allowing a refinement of the criteria for choosing the template. This will result in new experimental techniques and computer design methods that can be used to ensure that new organic products can be manufactured in in the optimal way without the risk of unexpected polymorphs appearing.

The determination of the structure of biological macromolecules using X-ray crystallography is providing information about how biological systems work at the level of individual molecules. This information has transformed our understanding of some of the fundamental processes of life. One example is the crystal structures of the protein haemoglobin in the presence and absence of oxygen which explain how blood cells are able to transport oxygen from the lungs to the tissues. A second example would be how the activity of metabolic enzymes such as glycogen phosphorylase are regulated so that cells either burn or store food depending on the nutritional state of the organism. In addition, crystal structures of key proteins can give important information about what happens at the molecular level in disease or infection and can guide the development of new drugs. A striking and topical example is the determination of the structure of the enzyme neuraminidase from the influenza virus. The structure was used to direct the development of the drugs relenza and subsequently tamiflu. Moreover, structures of neuraminidase and other influenza proteins allow us to understand why variants of flu (such as avian influenza or the Spanish flu of 1918) are so virulent, perhaps providing guidance on developing even better drugs. There are a number of steps in protein crystallography before a structure can be determined. The process starts with the production of large quantities of the protein of interest. The next, key step is to produce crystals of the protein. This can be a long and difficult process, finding the right solution conditions under which crystals will form. Crystals are necessary as when you shine X-rays on a crystal, you obtain a diffraction pattern from which, with a lot of effort, you can extract an image of what the structure of the molecule looks like. Therefore, the success of X-ray analysis is underpinned and determined by successful provision of crystals. In recent years, there have been continual improvements in both the design of the solution conditions and the robotics equipment available for setting up large numbers of crystallisation trials. A particularly important development has been the use of very small, nano-litre sized drops. These reduce the amount of protein that needs to be used, increases the number of crystallisation trials that can be conducted and in some cases, the small drops have increased the success of forming crystals. The Structural Biology Laboratory at York (YSBL) is one of the largest laboratories in Europe dedicated to the determination and analysis of protein structure. Scientists in YSBL have made major contributions by not only determining the structures of many important proteins, but also in developing the experimental and computational methods that are required for X-ray crystal structure determination. One element of this methods development has been devising new crystallisation screen solutions and also working with the manufacturers in developing improved robotics equipment. This application is for an upgrade to the robotics equipment that supports crystallisation trials in YSBL. This will allow scientists at York to benefit from some of the advances in equipment, to determine the structures of more proteins, more rapidly, but also to continue to work with manufacturers in making further improvements.