Nanoparticle wrapping at small non-spherical vesicles: curvatures at play.

Nanoparticles in biological systems encounter lipid-bilayer membranes as barriers. They interact with plasma membranes, membranous organelles, such as the endoplasmic reticulum and the Golgi apparatus, the nucleus, and intracellular and extracellular vesicles, such as autophagosomes, lysosomes, and exosomes. Extracellular vesicles have recently attracted particular attention, as they are involved in the transmission of biological signals and as regulators for biological processes. For example, exosomes, small vesicles containing proteins, mRNA, and miRNA, that are released by cells into the extracellular environment, have been suggested to participate in tumor metastasis. Furthermore, vesicles can be applied as targeted-drug-delivery systems. We systematically characterize wrapping of spherical nanoparticles that enter and exit vesicles, depending on particle size, vesicle size, vesicle reduced volume, and membrane spontaneous curvature. We predict the complex wrapping behavior, in particular for large particle-to-vesicle size ratios, where the shape changes of the free membrane contribute significantly to the deformation energy and where nanoparticle wrapping transitions and vesicle shape transitions are coupled. Partial-wrapped membrane-bound particles impose boundary conditions on the membrane that stabilise oblates and stomatocytes for particle entry, and prolates and stomatocytes for particle exit. Our results suggest that nanoparticles may stimulate autophagocytic engulfment, which would facilitate transport of the nanoparticles into lysosomes and would lead to subsequent degradation of nanoparticle-attached proteins.

Preparation, characterization and biodistribution in quails of 99mTc-folic acid/chitosan nanostructure.

Chitosan (CS) of low molecular weight is prepared using γ-irradiation method in presence of H2O2 as oxidizing agent. The chemical treatment of folic acid (FA) with low molecular weight CS is carried out to prepare FACS complex based on the reaction between NH2 group of CS and γ-COOH group of FA. The structure and properties of FACS complex was characterized by FT-IR, 1H NMR, UV, SEM, TEM, DLS and XRD analyses. TEM and DLS results showed that FACS complex has nanostructure and the mean size of particles was unimodal with average diameters in the range of 165-252nm. Radiolabeling of FACS complex (99mTc-FACS) was done with Technetium-99m (99mTc). The optimum conditions of labeling were investigated. The labeling yield was 85% at pH=6 and 30min reaction time. The effect of time on the stability of 99mTc-FACS complex was studied and the results revealed that it is stable up to 6h after labeling. Biodistribution studies of 99mTc-FACS complex in Quail showed that it distributed to different organs mainly in blood, liver and kidney. The results revealed that the uptake of 99mTc-FACS in the sexual organs (ovary and ovarian) of female Quail was higher than that in the sexual organs (testes) of male Quail, so 99mTc-FACS could be used to differentiate between them. It also showed that FACS is consumed and more essential in female than that in male.