Interaction between Water-Soluble Peptidic CdSe/ZnS Nanocrystals and Membranes: Formation of Hybrid Vesicles and Condensed Lamellar Phases

Abstract

Due to their tunable optical properties and their well-defined nanometric size, core/shell nanocrystals (quantum dots, QDs) are extensively used for the design of biomarkers as well as for the preparation of nanostructured hybrid materials. It is thus of great interest to understand their interaction with soft lipidic membranes. Here we present the synthesis of water-soluble peptide CdSe/ZnS QDs and their interaction with the fluid lipidic membrane of vesicles. The use of short peptides results in the formation of small QDs presenting both high fluorescence quantum yield and high colloidal stability as well as a mean hydrodynamical diameter of 10 nm. Their interaction with oppositely charged vesicles of various surface charge and size results in the formation of hybrid giant or large unilamellar vesicles covered with a densely packed layer of QDs without any vesicle rupture, as demonstrated by fluorescence resonance energy transfer experiments, zetametry, and optical microscopy. The adhesion of nanocrystals onto the vesicle membrane appears to be sterically limited and induces the reversion of the surface charge of the vesicles. Therefore, their interaction with small unilamellar vesicles induces the formation of a well-defined lamellar hybrid condensed phase in which the QDs are densely packed in the plane of the layers, as shown by freeze-fracture electron microscopy and small-angle X-ray scattering. In this structure, strong undulations of the bilayer maximize the electrostatic interaction between the QDs and the bilayers, as previously observed in the case of DNA polyelectrolytes interacting with small vesicles.

Quantum dots and nanoparticles for photodynamic and radiation therapies of cancer

“…Such folate-targeted lipodots were used to target lymphoma cells with upregulated folate receptor, while colon carcinoma cells not expressing folate receptor did not uptake the lipodots [67]. Zeta potential and fluorimetry titration were used to study adsorption of quantum dots on the surface of such unilamellar vesicles forming stable hybrid giant vesicles [90]. …”

Quantum Dot-Based Nanoprobes for In Vivo Targeted Imaging

“…In addition, the cores of QDs are typically coated with another semiconductor shell composed of materials with lower toxicity and wider band-gap (e.g. ZnS) [70, 71]. The presence of such a shell can not only improve the photoluminescence properties and passivate the surface traps, but also prevent the leaching of the highly toxic heavy metal ions from the QDs [72].…”

Polyvalent Display and Packing of Peptides and Proteins on Semiconductor Quantum Dots: Predicted Versus Experimental Results

“…As this chemistry employs a single, unique interaction site, it can also provide control over the spatial orientation of biomolecules on the QD surface while eliminating the issue of crosslinking found with other conjugation routes 17–19. This self‐assembly approach has been utilized to construct various QD‐based biosensing systems by facilitating the display of recombinant proteins/peptides, chemically modified nucleic acids, and synthetic peptides onto QD surfaces13, 19, 20 and has been successfully implemented by several other research groups 21–23…”