Magnetoliposomes consist of vesicles composed of a phospholipid membrane encapsulating magnetic nanoparticles. These systems have several important applications, such as in MRI contrast agents, drug and gene carriers, and cancer treatment devices. For all of these applications, controlling the number of encapsulated magnetic nanoparticles is a key issue. In this work, we used a magneto-optical technique to obtain information about the efficiency of encapsulation, the number of nanoparticles encapsulated per liposome and also about the formation of the nanoparticle structures. The parameters studied included the effect of the duration of sonication, the presence of cholesterol in the liposome membrane, as well as time-related stability. For the liposomal vesicles prepared in this work, we found between 35 and 300 nanoparticles encapsulated per liposome, depending on the experimental conditions, consisting of small linear chains of nanoparticles, basically trimers and tetramers. The methodology developed might be useful for the investigation and improvement of the properties of several magnetic nanocarrier systems.

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The isoflavone genistein (GEN) is a natural product with potential applications for skin cancer treatment and chemoprevention; however its high lipophilicity and chemical instability limits its clinical use. Therefore, attempts towards protecting GEN against degradation and increasing its penetration in the skin might be a valid approach. In this work, GEN loaded-PLA nanocapsules (GEN-NC) were prepared by interfacial deposition of preformed polymer (nanoprecipitation); physicochemical characterization and stability studies for 90 days were conducted. GEN-NC were incorporated into semi-solid formulations and permeation experiments were carried out using porcine ear skin. GEN-NC optimized formulation presented a mean diameter of 139 +/- 7.31 nm, polydispersity index of 0.128 +/- 0.08, encapsulation efficiency of 89.63 +/- 2.27% and drug loading from 0.6 to 1.4 w/w%. Stability studies demonstrated that nanocapsules did not exhibit aggregation during the 90 days of the assay, however, a drop in encapsulation efficiency was observed in the first 10 days. Permeation experiments demonstrated that a higher amount of GEN reaches deeper layers of the skin and increased penetration was achieved when GEN-NC were incorporated in a semi-solid gel formulation, indicating that GEN-NC might be a promising nanocarrier system for skin delivery of GEN.

Co-encapsulation of anticancer drugs paclitaxel and imatinib in nanocarriers is a promising strategy to optimize cancer treatment. Aiming to combine the cytotoxic and antiangiogenic properties of the drugs, a liposome formulation targeted to folate receptor co-encapsulating paclitaxel and imatinib was designed in this work. An efficient method was optimized for the synthesis of the lipid anchor DSPE-PEG(2000)-folic acid (FA). The structure of the obtained product was confirmed by RMN, FT-IR, and ESI-MS techniques. A new analytical method was developed and validated for simultaneous quantification of the drugs by liquid chromatography. Liposomes, composed of phosphatidylcholine, cholesterol, and DSPE-mPEG(2000), were prepared by extrusion. Their surface was modified by post-insertion of DSPE-PEG(2000)-FA. Reaction yield for DSPE-PEG(2000)-FA synthesis was 87%. Liposomes had a mean diameter of 122.85 ± 1.48 nm and polydispersity index of 0.19 ± 0.01. Lyophilized formulations remained stable for 60 days in terms of size and drug loading. FA-targeted liposomes had a higher effect on MCF7 cell viability reduction (p < 0.05) when compared with non-targeted liposomes and free paclitaxel. On PC-3 cells, viability reduction was greater (p < 0.01) when cells were exposed to targeted vesicles co-encapsulating both drugs, compared with the non-targeted formulation. VEGF gene expression was reduced in MCF7 and PC-3 cells (p < 0.0001), with targeted vesicles exhibiting better performance than non-targeted liposomes. Our results demonstrate that multifunctional liposomes associating molecular targeting and multidrug co-encapsulation are an interesting strategy to achieve enhanced internalization and accumulation of drugs in targeted cells, combining multiple antitumor strategies.

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