No abstract

The biodistribution of colloidal carriers after their administration in vivo depends on the adsorption of some plasma proteins and apolipoproteins on their surface. Poly(methoxypolyethyleneglycol cyanoacrylate-co-hexadecylcyanoacrylate) (PEG-PHDCA) nanoparticles have demonstrated their capacity to cross the blood-brain barrier (BBB) by a mechanism of endocytosis. In order to clarify this mechanism at the molecular level, proteins and especially apolipoproteins adsorbed at the surface of PEG-PHDCA nanoparticles were analyzed by complementary methods such as CE and Protein Lab-on-chip in comparison with 2-D PAGE as a method of reference. Thus, the ability of those methodologies to identify and quantify human and rat plasma protein adsorption onto PEG-PHDCA nanoparticles and conventional PHDCA nanoparticles was evaluated. The lower adsorption of proteins onto PEG-PHDCA nanoparticles comparatively to PHDCA nanoparticles was evidenced by 2-D PAGE and Protein Lab-on-chip methods. CE allowed the quantification of adsorbed proteins without the requirement of a desorption procedure but failed, in this context, to analyze complex mixtures of proteins. The Protein Lab-on-chip method appeared to be very useful to follow the kinetic of protein adsorption from serum onto nanoparticles; it was complementary to 2-D PAGE which allowed the identification (with a relative quantification) of the adsorbed proteins. The overall results suggest the implication of the apolipoprotein E in the mechanism of passage of PEG-PHDCA nanoparticles through the BBB.

Cationic solid lipid nanoparticles (SLN), reconstituted from natural components of protein-free low-density lipoprotein, were used to deliver small interfering RNA (siRNA). The cationic SLN was prepared using a modified solvent-emulsification method. The composition was 45% (w/w) cholesteryl ester, 3% (w/w) triglyceride, 10% (w/w) cholesterol, 14% (w/w) dioleoylphosphatidylethanolamine (DOPE), and 28% (w/w) 3beta-[ N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-chol). The SLN had a mean diameter of 117+/-12 nm and a surface zeta potential value of +41.76+/-2.63 mV. A reducible conjugate of siRNA and polyethylene glycol (PEG) (siRNA-PEG) was anchored onto the surface of SLN via electrostatic interactions, resulting in stable complexes in buffer solution and in even 10% serum. Under an optimal weight ratio of DC-chol of SLN and siRNA-PEG conjugate, the complexes exhibited higher gene silencing efficiency of GFP and VEGF than that of polyethylenimine (PEI) 25K with showing much reduced cell cytotoxicity. Flow cytometry results also showed that siRNA-PEG/SLN complexes were efficiently taken up by cells. Surface-modified and reconstituted protein-free LDL mimicking SLN could be utilized as noncytotoxic, serum-stable, and highly effective carriers for delivery of siRNA.