The present invention provides a way to capture a biomolecule such as a protein, virus enzyme or antibody in one or more layers of covalently bonded amorphous silica, forming a cage or shell which preserves the shape of the protein and prevents denaturation caused by heat and/or aging and/or non-physiological conditions, through unfolding and loss of secondary and/or higher order structure. The method of encapsulation requires hydrolysis of a silica precursor in the presence of an aqueous solution of biomolecule. The invention may be applied to the preservation of vaccines so that they may be provided in a gastric resistant form or as a dry form suitable for preservation without maintaining a cold-chain. The biomolecule may be released from the silica by the use of fluoride at acidic pH.
