Crystallisation in crowded media

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This project addresses a crucial knowledge gap in our understanding of how organisms control crystallisation processes to generate structures such as bones and seashells. A striking feature of biological environments is that almost every reaction occurs in highly crowded media;20-40% of the total volume is occupied with macromolecules, small organic molecules and ions. The vital importance of these crowded environments in the function of biological systems is such that dilute buffer solutions cannot provide a realistic representation of living systems.Biomineralisation processes are controlled by organic molecules. Significant efforts have therefore been made to determine the roles played by individual biomolecules in controlling mineralisation, where this is achieved by extracting macromolecules from biominerals, and testing their behaviour as crystallisation additives in vitro. Notably, these experiments are typically carried out in dilute, over- simplified reaction environments and most have failed to replicate key features of biological control such as selection of crystal polymorph. The one exception is the use of hydrogels as crystallisation environments, where these viscous media reduce convection. However, they are quite distinct from crowded macromolecular environments as they only present low solid contents (< 1wt%). It is therefore not possible to use these to tune the solution properties. This project will develop a new understanding of biomineralisation processes - and specifically the functions of control molecules ranging from small organic molecules to macromolecules - by evaluating their ability to direct crystallisation processes in crowded macromolecular environments. The origin of these effects will be investigated, and the understanding gained will be applied to synthetic systems, where many technologically-important materials can be prepared in crowded environments using polyol synthesis.