Role of surface ligands in optical properties of colloidal CdSe/CdS quantum dots

Abstract

In order to study the role of surface ligands in determining optical properties of colloidal quantum dots (QDs), we have selectively fabricated and studied CdSe/CdS core-shell QDs with strongly confined electron and hole states attached with commonly used surface ligands. Optical properties, viz. absorption and fluorescence of these QDs, are characterized from which salient changes have been observed for different ligand substitutions which, through theoretical analysis, can be associated with electronic structure properties of the QD-ligand composite systems, in particular localization of wave functions of electrons and holes in the QDs and the band matching of the HOMO-LUMO gap of the ligands. The findings can be utilized to facilitate the understanding and optimization of properties of QD biomarkers with functionalizing surface ligands for targeting cellular objects.

Optimization of the recipe for the synthesis of CuInS2/ZnS nanocrystals supported by mechanistic considerations

“…This organic layer will influence the absorption and PL properties of QDs. The ligands can effectively reduce the number surface defects of the ZnS layer but also can generate a possible nonradiative relaxation as a hole receptor [55,56]. In the synthesis of CIS/ZnS using TOP, the PL QY of CIS/ZnS is impacted by two factors.…”

“…On the one hand, the growth of ZnS shell reduced the number of defects on the crystal surface defects and improved the PL intensity, which has been already discussed; on the other hand, TOP representing a hole receptor on the surface of the particles promoted nonradiative relaxation and caused the decrease of PL intensity. Therefore, the improvement of the PL QYs of CIS/ZnS was limited using TOP [39,55,56]. The chain length of ligands is also one of the factors to affect PL improvement.…”

Quantum dots modulate intracellular Ca²⁺ level in lung epithelial cells

“…Their physiochemical properties have been carefully studied and reported, see previous reports. 19,20 Moreover, no perceptible changes in the optical spectra of QDs in the QD-treated Calu-3 samples stored for 6 months were observed, indicating that these QDs are well surface-passivated and are very stable in the Calu-3 cell culture media. 9 OGB-1 (50 µg/vial) was dissolved in 10 µL Pluronic F-127 (20%, w/v) to obtain a 4 mM stock solution.…”

Transport and release of colloidal 3-mercaptopropionic acid-coated CdSe–CdS/ZnS core-multishell quantum dots in human umbilical vein endothelial cells

“…[22][23][24] Since material properties of colloidal QDs are strongly related to QD's synthesis method, we described first the synthesis of our 3MPA-QDs consisting of three major steps. 1) The first step was to synthesize CdSe cores.…”

“…As one of the well-characterized vascular endothelial cells, human umbilical vein endothelial cells (HUVECs) express the typical endothelial phenotype and are often used in studying nanomaterial toxicity. [18][19][20][21] In this article, we investigated 3-mercaptopropionic acid-coated CdSe-CdS/ZnS core-multishell quantum dots (3MPA-QDs) obtained by surface ligand exchange of asgrown octadecylamine-coated quantum dots (ODA-QDs) [22][23][24] and exploited their transport, release and photophysical properties in HUVECs. We found that the variation of QD optical properties could be used as a fingerprint to accurately discriminate their spatial locations in intracellular compartments.…”