Abstract: Processes for making neutral or anionic complexes containing sequestered DNA for gene transfer, by forming a stable colloid containing an aqueous phase having suspended therein a first DNA complex with a cationic surface potential comprising a DNA sequence complexed with a cationic lipid or polymer, and modifying the surface potential of the first DNA complex to form a stable colloid comprising a second DNA complex with a neutral or net anionic surface potential.

Abstract: A method and composition which permits sterilization of surfaces coupled with biologically active moieties by ionizing radiation is described. The protecting composition contains a surface-stabilizing agent which adheres to the surface and has a molecular weight.gtoreq.5 kd, and an oxygen radical scavenger which is preferably a di- or polysaccharide or reduced form thereof. In the method of the invention, a surface which is coupled to a biologically active agent is protected with the invention composition, dried to a moisture content of less than 1%, and then sterilized by ionizing radiation under standard conditions. The sterilized surfaces of the invention are particularly useful in the production of medical devices intended for extracorporeal use, particularly in cell-separation techniques.