Methods of synthesis of chiral metallic and semiconductor nanoparticles and investigation of their properties are new trends in modern nanoscience [1, 2]. Chiral properties of nanoparticles can be achieved by the presence of chiral molecules on their surface, the asymmetry of the nanoparticle shape or self-organization [3-6].
Spherical semiconductor nanocrystals, quantum dots (QDs) possess quantum-size properties that allows change optical properties QDs by changing their size. QDs also have high absorption in a broad spectral range and bright luminescence. Modern colloidal synthetic methods provide QDs with a narrow size distribution and good photo and chemical stability. The properties of colloidal QDs make them very attractive as a core of new hybrid structure for cancer theranostics that combine diagnostic and therapeutic capabilities into a single agent [7, 8]. In the hybrid structures QDs can be used simultaneously as an efficient delivery agent, luminescent marker and efficient energy donor for molecules that generate active oxygen forms.
Recently it was found that using of chiral molecules as stabilizing agent of the QD surface can provide an optical activity both in the region of chiral molecule absorption and in the region of fundamental absorption of QDs [9, 10]. In biological media there are a lot of chiral components and these components can be sensitive to QD chirality. Therefore interaction of chiral QDs and their hybrid structures with chiral environment components in cells could influence on their photophysical properties and functionality. Evidently, that chirality of QDs can enhance specific interactions in cells and influence on intracellular interactions with chiral molecules.
Here we present a brightly luminescent chiral CdSe/ZnS QDs that were obtained via their solubilization with L- and D- enantiomeric forms of cystein. The chiral QDs demonstrated antiphase signal in circular dichroism spectrum in the range of their fundamental absorption. Investigation of QD penetration in Ascite Carcinoma Ehrlich (ACE) cells has shown that a chirality of QDs have an effect on their efficiency of penetration into the cells. It was discovered that an efficiency of penetration into ACE cells of L-enantiomeric QDs is two times higher than that of D-enantiomeric QDs. It was found that a conjugation of L-enantiomeric CdSe/ZnS QDs with L- enantiomeric chlorine e6 (Ce6) molecules using carbodiimide molecules (EDAC) as a linkage agent provides a stable QD/Ce6 complexes with efficient intracomplex energy transfer from QD to Ce6. The investigation of an influence of chirality of QDs on photophysical properties of QD/Ce6 complexes and their functionality in cells are future goals in our research.
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