The present invention relates generally to modifying biological and/or synthetic membranes or liposomes, or combinations thereof, for the purpose of altering immunity, or for the targeting of drugs and other agents to a specific cell type or tissue when administered in vivo to achieve a therapeutic effect. Modification of the membranes is achieved by incorporation and/or attachment of metal chelating groups, thereby allowing engraftment of one or more targeting molecules possessing a metal affinity tag, and a targeting of the engrafted membranes to specific cell types or tissues in vivo. The invention, thus, provides a means of modifying the properties of biological and/or synthetic membranes and liposomes for the purpose of altering or enhancing immunity when used as vaccines, or for the targeting of encapsulated/incorporated drugs or other agents to a specific cell type or tissue when administered in vivo, to achieve a therapeutic effect or response, or for modifying a physiological response or biological function.