This invention provides the use of a substantially ordered mesoporous oxide based material for the fixation or immobilisation of a biologically active species, especially in the form of a pharmaceutical composition, wherein said ordered oxide based material has one or more levels of porosity and structural order, provided that when said ordered oxide based material has a single level of porosity and structural order it is obtained in the absence of an alpha-tocopherol polyethylene glycol ester templating biomolecule.
