Multifunctional Conjugates To Prepare Nucleolar-Targeting CdS Quantum Dots

Abstract

We used a click reaction to synthesize a bidentate 1,2,3-triazole-based ligand, TA, for use in the preparation of aqueous CdS quantum dots (QDs). TA-conjugated CdS QDs exhibited two fluorescence emission peaks, one at 540 nm arising from CdS nanocrystals and the other at approximately 670 nm arising from TA-CdS QD complexes formed via surface coordination. Coordination between TA and CdS was verified by using X-ray photoelectron (N 1s) spectra as well as Raman and NMR spectra of TA-capped QDs. Electrochemical analysis revealed that the 1,2,3-triazole moities in TA form complexes with the Cd(II) ions. The aqueous QDs protected by TA were very stable at different ionic strengths and over a broad pH range, according to fluorescence analysis. The ethidium bromide exclusion assay demonstrated that the bidentate TA ligand interacts strongly with DNA. Fluorescent micrographs and TEM images of cancer cells stained with TA-capped QDs clearly showed that the TA ligand targeted CdS QDs to the nucleoli of cells. In contrast, thioglycolic acid-capped CdS QDs just stained the cell membranes and could not pass the cell membranes to reach the cell nucleus.

Ubiquinone-quantum dot bioconjugates for in vitro and intracellular complex I sensing

“…We introduced the quinoid moiety in the Q n NS ligands to achieve the redox-switchable fluorescence properties that could be useful for signal multiplexing. The 1,2,3-triazole groups, similar to histidine27, could enhance the compatibility of Q n NS -QDs in biological systems. Three alkyl linkers confer different abilities of electron-transfer to either the QDs' core or the surface of QDs.…”

Mercaptopropionic acid-capped Mn2+:ZnSe/ZnO quantum dots with both downconversion and upconversion emissions for bioimaging applications

“…At physiological pH, the negatively charged MPA-Mn 2+ :ZnSe/ ZnO d-dots might bind to positively charged basic proteins, such as histone, which are abundant in cell nuclei, and may be the driving force of the nucleus-targeting functions of MPA-Mn 2+ :ZnSe/ZnO d-dots. However, the size of MPA-Mn 2+ : ZnSe/ZnO d-dots is about 6.7 nm, which is much bigger than that of the reported nucleus-targeting QDs (glutathione (GSH)-capped CdTe (4.0 nm), 45 thioglycolic acid (TGA)-capped CdTe (3.6 and 2.6 nm) 46 and 1,2,3-triazole-PEG (TA)-capped CdS (<4.0 nm) 47 ). A detailed study of the nucleus-targeting functions of MPA-Mn 2+ :ZnSe/ZnO d-dots will be carried out in the future.…”

Redox-Mediated Quantum Dots as Fluorescence Probe and Their Biological Application

“…In addition, in situ fluorescence spectra-electrochemical results further validate that the reduced state of ubiquinols significantly increase the fluorescence of QD bioconjugates, while the oxidized state of the ubiquinones decrease the fluorescence at varying degrees. To further enhance the compatibility of ubiquinone-QD bioconjugates in biological system, the ligands Q 2 NS, Q 5 NS, and Q 10 NS were designed and synthesized by a facile click reaction between ubiquinone with terminal alkynes and alkylazide-disulfides via copper(I) tris (benzyltriazolylmethyl) amine catalyzed 1,2,3-triazole formation [37] (Figure 3a). In this system, the quinoid moiety in the Q n NS surface ligands was introduced to achieve the redoxswitchable fluorescence properties for signal multiplexing.…”