Preservation of biological molecules and living cells

Protection of biological molecules during freezing and lyophilization is a subject of considerable importance to the food, pharmaceutical and biotechnology industries. Thus, much work has been done to develop compounds which will stabilize biological products during processing and storage. Chief among these compounds are the saccharides. They have been found to protect proteins during freezing and drying as well as prevent damaging membrane changes on cooling in cells. Trehalose, a naturally occurring disaccharide of glucose, has been found to be a highly effective cryoprotectant. Previous work in my group has helped put the fundamental thermophysical properties of trehalose and its aqueous solutions on a better footing. Also, novel formulations were developed based on interactions between trehalose and borate ions which enhances the protective capacity of the solution.;Although there are several prevailing structural and thermodynamic arguments as to why molecules like trehalose act as cryoprotectants, little fundamental work has been done to support or refute these hypotheses. To address this gap in our understanding, much of my work has focussed on molecular simulation of solution behavior of trehalose in aqueous solutions as well as the underlying phase behavior of supercooled amorphous water. I have also taken insights gained from the simulations and used them in the development of a next-generation cryoprotectant system which has all the advantages of the trehalose-borate formulation but relies on phosphate as the solution modifier. Inclusion of the biologically compatible phosphate salts have shown tremendous benefit for enzyme and cell preservation.;There are a number of aspects to this work that have yet to be fully pursued including application to mammalian cells and tissues, techniques for introduction of trehalose to the cytosol, the effect of phosphate in mixed polyol systems, and the molecular behavior of trehalose complexes near lipid membranes. It is my hope that the studies presented herein will act as a guide for future work in this field.