Improved oligonucleotide uptake and stability by a new drug carrier, the SupraMolecular Bio Vector (SMBV).

Antisense oligodeoxynucleotides are potential therapeutic agents, but their development is still limited by both a poor cellular uptake and a high degradation rate in biological media. The strategy that we propose to face these problems is to use small synthetic carriers, around 30 nm diameter, the SupraMolecular Bio Vectors (SMBV). We used positively charged SMBV and settled the ionic incorporation of negatively charged oligonucleotides into these carriers. A minimal leakage of 10% of total incorporated oligonucleotides was then measured during two months. Both protection and uptake of oligonucleotides were then analyzed. On the one hand, we showed that the incorporation of oligonucleotides into the selected SMBV allows to significantly increase, 8 times, their half-life, in cell growth medium. On the other hand, the internalization of the SMBV, into cells, by an endosomal pathway has been characterized. The essential point is that the SMBV uptake elicits the simultaneous oligonucleotide uptake. The oligonucleotide amount that goes through cells within 5 h can be up to 30 times higher than for free oligonucleotides and the fraction of oligonucleotides that is present in the cytosol is increased up to 10 fold after incorporation into the SMBV. This study demonstrates the ability of SMBV to improve oligonucleotide cellular behaviour.

Synthesis and characterization of supramolecular biovector (SMBV) specifically designed for the entrapment of ionic molecules.

Supramolecular biovectors (SMBV) are nanoparticular drug carriers composed of an internal crosslinked solid core externally grafted with fatty acids and surrounded with a phospholipid layer. We show in this paper that the internal core can be derivatized with anionic ligands such as phosphate in order to allow the efficient entrapment of cationic molecules through a process akin to ion exchange. Synthesis of SMBV involved first a cross linking and derivatization step of polysaccharides followed by a homogenization, a drying and a regioselective acylation step. Acylated polysaccharide cores are thus obtained which can be loaded with drugs and wrapped with a phospholipid layer. The SMBVs obtained are characterized through their size, 20 nm, and their ability to filter through 0.22 microns pore size membrane. Gel permeation chromatography experiments performed with various phospholipid/acylated cores ratios indicate that SMBVs form entities distinct from liposomes and that the optimum phospholipid/acylated cores ratio for this specific type of SMBVs is close to 100%. The supramolecular structure of SMBVs and in particular the spatial proximity between acylated cores and phospholipids is demonstrated through resonance energy transfer experiments. The drug loading capability of SMBVs is illustrated by the preparation of gentamicin and doxorubicin loaded SMBV. The therapeutic potential of SMBVs is then discussed notably in the light of a possible biomimetism with low density lipoproteins (LDL).

Proofs of the structure of lipid coated nanoparticles (SMBV) used as drug carriers.

PURPOSE: Supramolecular Biovectors (SMBV) consist of cross-linked cationic nanoparticles surrounded by a lipid membrane. The purpose was to study the structure of the lipid membrane and to characterise its interaction with the nanoparticles in order to differentiate SMBV from other polymer/lipid associations. METHODS: The interaction of lipids with the nanoparticle surface was studied using zeta potential. Fluorescence Energy Transfer (FET) and Fluorescence Microscopy. SMBV were compared to liposomes and mixtures nanoparticles/liposomes. Finally the structure of SMBV was visualised by Electron Microscopy. RESULTS: Zeta potential measurements showed that lipids on SMBV had a pronounced shielding effect on the surface charge. This was not the case for mixtures of nanoparticles and liposomes. FET experiments confirmed these results indicating that, for SMBV, the lipids are much closer to the nanoparticle surface. SMBV Fluorescence microscopy on model microparticles showed a lipid crown on SMBV that was confirmed by electron microscopy on SMBV nanoparticles. CONCLUSIONS: Results show that in case of SMBV lipids are strongly adsorbed on the polysaccharide core surface probably due to ionic/hydrophobic interactions. The resulting supramolecular structure is a spherical cationic polysaccharide particle surrounded by a phospholipid/cholesterol layer.

Design and antileishmanial activity of amphotericin B-loaded stable ionic amphiphile biovector formulations.

A new delivery system, Ionic Amphiphilic Biovector (ABV), comprised of anionic lipids (dipalmitoyl phosphatidyl glycerol) included in a cationic cross-linked polysaccharide matrix was used as a reservoir for amphotericin B (AmB). Two ABV formulations exhibited an in vitro and in vivo efficacy similar to commercial AmBisome against Leishmania donovani-infected mice. The higher stability of these ABV formulations indicates their potential for further development and applications.