Liposomes Prepared from Synthetic Amphiphiles. I. : Their Technetium Labeling and Stability

Abstract

In order to apply liposomes prepared from synthetic amphiphiles containing amino acid residues to radiopharmaceuticals, their labeling with ⁹⁹Tc or ^99mTc and stability in saline or in serum were investigated. These liposomes were highly labeled by embedding stearylamine-diethylenetriamine pentaacetic acid as a ligand of technetium. The labeling was more efficient at pH 7.0 than at pH 4.0 or 8.5. Among these technetium-labeled liposomes tested, liposomes containing the alanine residue were stable in saline or in 50% serum at 37°C for at least 24h, in contrast to liposomes (phosphatidylcholine : cholesterol=1 : 1 molar ratio) whose stability had been enhanced by adding cholesterol.