Storage of materials

Abstract

Materials which are not themselves storage-stable at room temperature are made suitable for storage by mixing them with a carrier substance and spray drying the resulting mixture so as to form particles containing both the material and the carrier substance in which the carrier substance is in an amorphous, i.e. glassy or rubbery, state. Formation of such a composition greatly enhances stability. The material stored may be a biological material such as an enzyme, the components of a chemical reaction such as reagents for carrying out an assay, or even viable biological cells.

1 . A process of rendering a material suitable for storage comprising spraying into a hot gas stream an aqueous mixture of the said material and a carrier substance which is water-soluble or water-swellable, thereby drying the mixture to particles which contain the material and the carrier substance and in which the said carrier substance is in a glassy or rubbery state, and separating the particles from the gas stream.  
     
     
         2 . A process according to  claim 1  wherein the carrier substance, when on its own, is able to exist in a glassy amorphous state with a glass transition temperature above 20° C.  
     
     
         3 . A process according to  claim 1  wherein the composition produced by the drying procedure displays a glass transition temperature of at least 20° C.  
     
     
         4 . A process according to  claim 1  wherein the composition produced by the drying procedure displays a glass transition temperature of at least 50° C.  
     
     
         5 . A process according to  claim 1  wherein the carrier substance forms at least 20% by weight of the particles formed by drying.  
     
     
         6 . A process according to  claim 1  wherein the composition produced by the drying procedure displays a glass transition temperature of at least 50° C.  
     
     
         7 . A process according to  claim 1  wherein the material which is rendered suitable for storage is selected from proteins, peptides, nucleosides, nucleotides, dinucleotides, oligonucleotides and enzyme cofactors.  
     
     
         8 . A process according to  claim 1  wherein the material to be stored comprises viable biological cells.  
     
     
         9 . A process according to  claim 8  wherein the aqueous mixture sprayed into the gas stream comprises a suspension of the cells in growth medium for the cells.  
     
     
         10 . A process according to  claim 1  wherein the carrier substance is a polyhydroxy compound.  
     
     
         11 . A process according to  claim 10  wherein the carrier substance is a carbohydrate.  
     
     
         12 . A process according to  claim 1  wherein the carrier substance is protein or a protein hydrolysis product.  
     
     
         13 . A process according to  claim 1  wherein the carrier substance is a sugar polymer containing sugar residues linked through ether bridges to bifunctional groups other than carbohydrate.  
     
     
         14 . A storable composition produced by the process of  claim 1.