peer journals

Encapsulation of Zwitterionic Au nanocrystals into liposomes by Reverse Phase Evaporation Method: Influence of The Surface Charge.

Since both liposomes and nanoparticles have shown great potential in application for clinical diagnostics and therapeutics, the perfect combination of the two materials is appealing for further improving the theranostic eff ect. Therefore, fabrication of liposomes loaded with nanoparticles in a controllable manner is desirable. Detection of various factors aff ecting encapsulation needs to be assigned. Here, we use zwitterionic Au nanoparticles (Au± NPs) coated with a mixture of 11-mercaptoundecanoic acid and N ,N ,N -trimethyl(11- mercaptoundecyl) ammonium chloride to study their encapsulation behavior by reversed phase evaporation (REV) method.To produce a reverse emulsion, an organic solution of dipalmitoylphosphatidylcholine(DPPC) and 1,2-dioleoyl-sn -glycero-3- phosphoethanolamine-N -[methoxy(poly(ethylene glycol))-2000] (ammonium salt) (PEG2000-DOPE) is mixed with an aqueous Au± NP colloidal solution under sonication. The pH of the colloidal solution controls the surface charge of the Au± NPs and then tunes the interactions between Au± NPs and phospholipids. At lower pH, the positive surface charges favor Au± NP transfer into the organic phase and consequently prevent their encapsulation into liposomes. The effi ciency in encapsulation is markedly improved by increasing the pH of the Au± NP colloidal solution. The highest effi ciency is obtained at a pH value slightly larger than the isoelectric point. Further pH increase induces a decrease in encapsulation effi ciency. This is due to increase of the repulsive forces between Au± NPs and phospholipids indicating that both the nature (positive or negative) and the amount of surface charge are key parameters in the encapsulation effi ciency. We also fi nd that the increase in Au± NP concentration favors the encapsulation process.

Source : Encapsulation of Zwitterionic Au nanocrystals into liposomes by Reverse Phase Evaporation Method: Influence of The Surface Charge. L.Wang and M.P. Pileni Langmuir, 2016, 32, 12370−12377.

peer journals

Dispersion of Hydrophobic Co Supracrystal in Aqueous Solution.

Assembly of nanoparticles into supracrystals provides a class of materials with interesting optical and magnetic properties. However supracrystals are mostly obtained from hydrophobic particles and therefore cannot be manipulated in aqueous systems limiting their range of applications. Here we show that hydrophobic shaped supracrystals self-assembled from 8.2 nm cobalt nanoparticles can be dispersed in water by coating the supracrystals with lipid vesicles. A careful characterization of these composites objects provides insights into their structure at different length scales. The novel composite, suspended in water, retains the crystalline structure and paramagnetic properties of the starting material, which can be moved with an applied magnetic field. It opens the routes to potential biological and biotechnological applications

Source : Dispersion of Hydrophobic Co Supracrystal in Aqueous Solution. N. Yang, Z. Yang, M. Held, P. Bonville, P.A. Albouy, R. Lévy, M.PPileni ACS Nano,2016 , 10, 2277–2286

peer journals

Water-Dispersed Hydrophobic Au Nanocrystal Assemblies with a Plasmon Fingerprint

Hydrophobic Au nanocrystal assemblies (both ordered and amorphous) were dispersed in aqueous solution via the assistance of lipid vesicles. The intertwine between vesicles and Au assemblies was made possible through a careful selection of the length of alkyl chains on Au nanocrystals. Extinction spectra of Au assemblies showed two peaks that were assigned to a scattering mode that red-shifted with increasing the assembly size and an absorption mode associated with localized surface plasmon, that was independent of their size. This plasmon fingerprint could be used as a probe for investigating the optical properties of such assemblies. Our water-soluble assemblies enable exploring a variety of potential applications including solar energy and biomedicine.

Source : Water-Dispersed Hydrophobic Au Nanocrystal Assemblies with a Plasmon Fingerprint. Yang, C.Deeb, J.L Pelouard, N. Felidj and M.P. Pileni ACS Nano, 2017,11, 7797−7806.