In vivo study of the mucus-permeating properties of PEG-coated nanoparticles following oral administration.

The aim of this work was to investigate the mucus-permeating properties of poly(ethyleneglycol)-coated nanoparticles prepared from the copolymer of methyl vinyl ether and maleic anhydride (Gantrez® AN) after oral administration in rats. Nanoparticles were "decorated" with PEGs of different molecular masses (PEG2000, PEG6000 and PEG10000) at a PEG-to-polymer ratio of 0.125. All the PEG-coated nanoparticles displayed a mean size of ∼150 nm, slightly negative ζ values and a "brush" conformation as determined from the calculation of the PEG density. For in vivo studies, nanoparticles were labelled with either (99m)Tc or fluorescent tags. Naked nanoparticles displayed a higher ability to interact with the mucosa of the stomach than with the small intestine. However, these interactions were restricted to the mucus layer covering the epithelial surface, as visualised by fluorescence microscopy. On the contrary, PEG-coated nanoparticles moved rapidly to the intestine, as determined by imaging, and, then, were capable to develop important interactions with the mucosa, reaching the surface of the epithelium. These mucus permeating properties were more intense for nanoparticles coated with PEG2000 or PEG6000 than with PEG10000. However, the capability of nanocarriers to develop adhesive interactions within the mucosa decreased when prepared at excessive PEG densities.

The extradomain a of fibronectin enhances the efficacy of lipopolysaccharide defective Salmonella bacterins as vaccines in mice.

The Extradomain A from fibronectin (EDA) has an immunomodulatory role as fusion protein with viral and tumor antigens, but its effect when administered with bacteria has not been assessed. Here, we investigated the adjuvant effect of EDA in mice immunizations against Salmonella enterica subspecies enterica serovar Enteritidis (Salmonella Enteritidis). Since lipopolysaccharide (LPS) is a major virulence factor and the LPS O-polysaccharide (O-PS) is the immunodominant antigen in serological diagnostic tests, Salmonella mutants lacking O-PS (rough mutants) represent an interesting approach for developing new vaccines and diagnostic tests to differentiate infected and vaccinated animals (DIVA tests). Here, antigenic preparations (hot-saline extracts and formalin-inactivated bacterins) from two Salmonella Enteritidis rough mutants, carrying either intact (SEΔwaaL) or deep-defective (SEΔgal) LPS-Core, were used in combination with EDA. Biotinylated bacterins, in particular SEΔwaaL bacterin, decorated with EDAvidin (EDA and streptavidin fusion protein) improved the protection conferred by hot-saline or bacterins alone and prevented significantly the virulent infection at least to the levels of live attenuated rough mutants. These findings demonstrate the adjuvant effect of EDAvidin when administered with biotinylated bacterins from Salmonella Enteritidis lacking O-PS and the usefulness of BEDA-SEΔwaaL as non-live vaccine in the mouse model.

Oral administration of paclitaxel with pegylated poly(anhydride) nanoparticles: permeability and pharmacokinetic study.

The aim of this work was to study the potential of pegylated poly(anhydride) nanoparticles as carriers for the oral delivery of paclitaxel (PTX). Paclitaxel is an anticancer drug, ascribed to the class IV of the Biopharmaceutical Classification system, characterised for its low aqueous solubility and to act as a substrate of the P-glycoprotein and cytochrome P450. For the pegylation of nanoparticles, three different poly(ethylene glycol) (PEG) were used: PEG 2000 (PTX-NP2), PEG 6000 (PTX-NP6) and PEG 10,000 (PTX-NP10). The transport and permeability of paclitaxel through the jejunum mucosa of rats was determined in Ussing chambers, whereas its oral bioavailability was studied in rats. The loading of PTX in pegylated nanoparticles increased between 3 and 7 times the intestinal permeability of paclitaxel through the jejunum compared with the commercial formulation Taxol. Interestingly, the permeability of PTX was significantly higher for PTX-NP2 and PTX-NP6 than for PTX-NP10. In the in vivo studies, similar results were obtained. When PTX-NP2 and PTX-NP6 were administered to rats by the oral route, sustained and therapeutic plasma levels of paclitaxel for at least 48 h were observed. The relative oral bioavailability of paclitaxel delivered in nanoparticles was calculated to be 70% for PTX-NP2, 40% for PTX-NP6 and 16% in case of PTX-NP10. All of these observations would be related with both the bioadhesive properties of these carriers and the inhibitory effect of PEG on the activity of both P-gp and P450 cytochrome.

Influence of dextran on the bioadhesive properties of poly(anhydride) nanoparticles.

This work describes the bioadhesive properties of poly(methyl vinyl ether-co-maleic anhydride) (Gantrez AN) nanoparticles (NP) associated with various types of dextran (two hydroxyl-functionalized dextrans and one amino-derivative of dextran). The association of dextran to the polymer was performed either prior NP formation or by the attachment of dextran to the surface of the just formed NP. The amount of dextran associated to the nanoparticles was quantified by a HPLC/ELSD method and dextran presence in the nanoparticles was confirmed by IR spectroscopy, (1)H NMR and in vitro agglutination assay. The in vivo bioadhesion study has demonstrated significantly higher adhesive interactions with the gastrointestinal tract of rats for all types of dextran associated nanoparticles compared with control nanoparticles. For nanoparticles associated with the aminated-dextran, the curves of bioadhesion were characterized by a maximum of adhesion just after administration followed by a rapid and constant decline with time. On the contrary, nanoparticles associated to conventional dextrans displayed a maximum bioadhesion between 1 and 3h post-administration. These results encourage us for further use of these systems for oral delivery of drugs.

An HPLC with evaporative light scattering detection method for the quantification of PEGs and Gantrez in PEGylated nanoparticles.

A rapid and precise HPLC method with evaporative light scattering detection (ELSD) for the separation and quantification of polyethyleneglycol 2000 (PEG 2000), polyethyleneglycol 6000 (PEG 6000) and poly(methyl vinyl ether-co-maleic anhydride) (Gantrez) in a nanosized pharmaceutical formulation has been developed. Separation was carried out on a PL aquagel-OH 30,8 microm column (300 mm x 7.5 mm), in a gradient elution with methanol-water as mobile phase at a flow rate of 1 ml/min. Quantification was determined in supernatants of PEGylated nanoparticles and the quantification limits were found to be 0.075 mg/ml for polyethyleneglycols and 0.25 mg/ml for Gantrez. The precision did not exceed 8% and accuracy range for PEGs (-11.50 and 10.61%) and Gantrez (-12.18 and 14.81%) were always within the acceptable limits. The amount of polyethyleneglycol associated to nanoparticles was also calculated by a Nuclear Magnetic Resonance Method ((1)H NMR). Likely, for both PEGs, a good relationship between both techniques was found. In summary, the developed HPLC technique provides an alternative for the routine and rapid analysis of PEGs and Gantrez in nanoparticle formulations.