Sirolimus Encapsulated Liposomes for Cancer Therapy: Physicochemical and Mechanical Characterization of Sirolimus Distribution within Liposome Bilayers

• Published in: Molecular pharmaceutics Vol. 10; no. 11; pp. 4281 - 4293
• Main Authors: Onyesom, Ichioma, Lamprou, Dimitrios A, Sygellou, Lamprini, Owusu-Ware, Samuel K, Antonijevic, Milan, Chowdhry, Babur Z, Douroumis, Dennis
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 04-11-2013
• Subjects: 1,2-Dipalmitoylphosphatidylcholine - chemistry; Calorimetry, Differential Scanning; Liposomes - chemistry; Microscopy, Atomic Force; Sirolimus - chemistry; stealth liposomes; atomic force microscopy; X-ray photon electron analysis; mechanical properties; sirolimus
• ISSN: 1543-8384; 1543-8392
• DOI: 10.1021/mp400362v

Sirolimus has recently been introduced as a therapeutic agent for breast and prostate cancer. In the current study, conventional and Stealth liposomes were used as carriers for the encapsulation of sirolimus. The physicochemical characteristics of the sirolimus liposome nanoparticles were investigated including the particle size, zeta potential, stability and membrane integrity. In addition atomic force microscopy was used to study the morphology, surface roughness and mechanical properties such as elastic modulus deformation and deformation. Sirolimus encapsulation in Stealth liposomes showed a high degree of deformation and lower packing density especially for dipalmitoyl-phosphatidylcholine (DPPC) Stealth liposomes compared to unloaded. Similar results were obtained by differential scanning calorimetry (DSC) studies; sirolimus loaded liposomes were found to result in a distorted state of the bilayer. X-ray photon electron (XPS) analysis revealed a uniform distribution of sirolimus in multilamellar DPPC Stealth liposomes compared to a nonuniform, greater outer layer lamellar distribution in distearoylphosphatidylcholine (DSPC) Stealth liposomes.