Characterization of the Ligand Exchange Reactions on CdSe/ZnS QDs by Capillary Electrophoresis

Abstract

The continuous development of semiconductor quantum dots (QDs) in biochemical research has attracted special attention, and surface functionalizing becomes more important to optimize their performance. Ligand exchange reactions are commonly used to modify the surface of QDs for their biomedical applications. However, the kinetics of ligand exchange for semiconductor QDs remain fully unexplored. Here, we describe a simple and rapid method to characterize the ligand exchange reactions on CdSe/ZnS QDs by capillary electrophoresis (CE). The results of ultraviolet–visible absorption spectra, fluorescence spectra, and Fourier transform infrared spectroscopy indicated the successful implementation of the ligand exchange process. The dynamics of ligand exchange of OA-coated CdSe/ZnS QDs with 4-mercaptobenzoic acid was monitored by CE, and the observed ligand exchange trends were fitted with logistic functions. When the ligand exchange reactions reached equilibrium, the ligand density of QDs can be quantified by CE. It is anticipated that CE will be a new powerful technique for quantitative analysis of the ligand exchange reactions on the surface of QDs.

One-Step Synthesis of Water-Soluble Quantum Dots from Ag2S and AgInS2 QDs

“…Ternary AIS QDs have been studied and obtained by several methods, including the hydrothermal method, , pyrolysis method, and ligand exchange method. , Torimoto et al prepared highly luminescent ZnS–AIS solid solution nanoparticles without toxic elements by pyrolysis . The obtained particles exhibited a wide photoluminescence (PL) spectrum, and the emission color could be changed from green to red.…”

“…Ternary AIS QDs have been studied and obtained by several methods, including the hydrothermal method, 21,22 pyrolysis method, 23 and ligand exchange method. 24,25 Torimoto et al…”

A Simplified Approach for the Aqueous Synthesis of Luminescent CdSe/ZnS Core/Shell Quantum Dots and Their Applications in Ultrasensitive Determination of the Biomarker 3-Nitro-l-tyrosine

“…The properties of the material can be manipulated by changing the core size and/or shell thickness. Further, the surface of the core/shell can easily be functionalized for specific applications. , …”

“…Further, the surface of the core/shell can easily be functionalized for specific applications. 25,26 There are several reports on the synthesis of core/shell nanoparticle QDs via non-aqueous media, like trioctylphosphine (TOP) and trioctylphosphene oxide (TOPO), hexadecylamine (HDA), etc. The quantum yield (QY) of the synthesized core/shell particles is high in organic solvents.…”

The binding affinity of monoalkyl phosphinic acid ligands towards nanocrystal surfaces

“…For example, thiols have a high affinity for the surface of metal chalcogenide or metallic NCs, but are generally poor ligands for metal oxides. 20,21,24,40,[45][46][47][48][49] Finally, a ligand exchange reaction can be forced by the formation of energetically favourable by-products. For example, the strong silicon-oxygen bond drives the exchange reaction from phosphonate to chloride by addition of trimethylsilyl chloride.…”