Surface Pressure Analysis of Poly(ethylene oxide)-Modified Fusogenic Liposomes Incorporated into a Phospholipid Monolayer

Fusogenic liposomes have a wide-range of applications as DDS and gene/protein delivery into living cells. A variety of surface modifications of drug carriers, to enable fusion with cells, have been proposed, however, the mechanism of fusion has still not been determined. To further improve the efficiency of drug carriers, a simple and easily examinable model of a living cell surface is needed. In this study, the time-course of a fusion phenomena was made by measuring the surface pressure increase of a phospholipid monolayer spread at the air/water interface due to the fusion of liposomes carrying PEO-lipid (dialkyl-terminated polyethylene oxide) reconstituted on their outer surface. The kinetics of the surface pressure change appeared to be bimodal, indicating the coexistence of different fusion pathways. It was found that the presence of the PEO-lipid on the liposome surface led to a faster lipid transfer compared to non-modified DMPC liposomes. This indicated that the reconstitution of PEO-lipid provided an alternative transfer pathway to that for non-fusogenic liposomes that show only a slow lipid transfer to phospholipid monolayers. The relation between the rate of fusion and the surface pressure of the host membrane is discussed.

Selective and Effective Cytotoxicity of Folic Acidconjugated Cholesteryl Pullulan Hydrogel Nanoparticles Complexed with Doxorubicin inΓIn Vitro and ΓIn Vivo Studies

We previously reported that cholesteryl pullulan (CHP) derivatives were effective carriers drug delivery systems in targeting cancer cells. We have now synthesized folic acid-conjugated CHP hydrogel nanoparticles (FACHP). FA-CHP complexed with the anticancer drug doxorubicin (DOX) show a higher cytotoxicity than CHP complexed with DOX in in vitro studies. The expression of a folate receptor (FR) is elevated in many cancers; in this case, confocal image analysis revealed that FA-CHP complexed with DOX exhibited greater cellular uptake than CHP complexed with DOX in human epidermal carcinoma (KB) cells over-expressing surface FR. In vivo studies showed that the increase of tumor volume in a nude mice xenograft model was significantly suppressed. Accordingly, FA-CHP may be an effective vehicle for the delivery of anticancer drugs and has a potential application in the treatment of overexpressing FR solid tumor cells.

Reduction breakable cholesteryl pullulan nanoparticles for targeted hepatocellular carcinoma chemotherapy

Reduction breakable nanoparticles derived from pullulan enhanced the tumor accumulation and intracellular release of DOX in hepatocellular carcinoma.

Folate-decorated maleilated pullulan-doxorubicin conjugate for active tumor-targeted drug delivery

A novel folate-decorated maleilated pullulan-doxorubicin conjugate (abbreviated as FA-MP-DOX) for active tumor targeting was set up. The structure of this conjugate was confirmed by (1)H NMR analysis. Furthermore, the conjugation efficiency, drug release property and stability of the conjugate were determined. The cellular uptake and cytotoxicity were assessed by using ovarian carcinoma A2780 cells as in vitro cell model. In vitro DOX release from FA-MP-DOX conjugate occurred at a faster rate at acidic pH compared to neutral pH (7.4). After 30 h of incubation at pH 2.5, 5.0 and 7.4 the released free DOX was about 68.71%, 50.08% and 26%, respectively. Based on the IC(50) values, the conjugate was found more effective with ovarian carcinoma A2780 cells than the parent drug after 48 h culture. These results suggested that FA-MP-DOX conjugate could be a promising doxorubicin carrier for its targeted and intracellular delivery.

Preparation and characterization of stearic acid-pullulan nanoparticles

For a new anticancer drug carrier, we synthesized 4 compositions of amphiphilic stearic acidconjugated pullulan (SAP) and characterized them with FT-IR spectroscopy. Crystalline changes were verified by x-ray diffraction patterns before and after synthesis of the SAP conjugate. SAP nanoparticles were prepared by a diafiltration method, and the fluorescence spectroscopy using pyrene showed particle self-assembly in water. SAP nanoparticles were spherical in TEM photos, and particle size ranged between 200 approximately 500 nm in photon correlation spectroscopy. Release of all-trans-retinoic acid from the SAP nanoparticles was maintained over 5 weeks. For further study in vivo, we tested the cytotoxicity of SAP nanoparticles using an MTT assay, and cytotoxicity was augmented as the molar mass of stearic acid increased in human liver carcinoma HepG2 cells. Therefore, SAP nanoparticles might be a promising longterm delivery carrier for hydrophobic therapeutic molecules with the appropriate composition.

New Polysaccharide-based Microparticles Crosslinked with Siloxane: Interactions with Biologically Active Substances

The interaction of microparticles of carboxymethyl pullulan crosslinked with siloxane (provided by a new crosslinking agent: 3-(glycid oxypropyl) trimethoxysilane) with biologically active molecules, such as enzymes (lysozyme) and drugs (propranolol, quinidine) was studied. The anionic amphiphilic supports retained through electrostatic and/or hydrophobic forces, variable amounts of the substances as a function of their structure, such as crosslinking degree and amount of uncrosslinked alkylsilane chains. The absorption of lysozyme on the supports followed the Langmuir isotherm, which allowed the calculation of constants k1 and k2. Both retention and in vitro release behavior of these support potential applications in controlled drug release as well as immobilization and purification of enzymes.