Controlled loading of liposomes with radionuclides for diagnostic imaging and radiotherapy

摘要

Radiolabeled liposomes can be used to evaluate thein vivo behavior of different liposome formulations, aswell as for diagnostic imaging and radiotherapy. In thisstudy we have developed a fully automated method forfast and easy preparation of liposomes with encapsulatedradionuclides. The encapsulation of 64Cu in liposomeswas tested using passive- and active loading. The highestencapsulation efficiency of 64Cu was achieved throughactive loading (91.8%) using oxine as an ionophore totransport the radionuclide over the bilayer of preformedchelator (DTPA) containing liposomes. The activeloading procedure was further optimized throughIsothermal Titration Calorimetry (ITC) measurements.Determining the affinity of the radionuclides to thedifferent chelators and ionophores used for loading, aregulation of the concentration of the differentcomponents during the active entrapment procedureallowed for rational encapsulation optimization. Theradiolabeled liposomes were stable in human serum at37°C for 24 h, and are potential carriers for otherradionuclides and useful tools in tumor imaging andradiotherapy.