Ming-Qiang Zhu

Green chemistry for large-scale synthesis of semiconductor quantum dots.

Large-scale synthesis of semiconductor nanocrystals or quantum dots (QDs) with high concentration and high yield through simultaneously increasing the precursor concentration was introduced. This synthetic route conducted in diesel has produced gram-scale CdSe semiconductor quantum dots (In optimal scale-up synthetic condition, the one-pot yield of QDs is up to 9.6g). The reaction has been conducted in open air and at relatively low temperature at 190-230 degrees C in the absence of expensive organic phosphine ligands, aliphatic amine and octadecene, which is really green chemistry without high energy cost for high temperature reaction and unessential toxic chemicals except for Cd, which is the essential building block for QDs.

Surface modification and functionalization of semiconductor quantum dots through reactive coating of silanes in toluene

We have reported a general method for biocompatible modification and multi-functionalization of semiconductor quantum dots (QDs) through direct reaction of organic silanes on the surface of semiconductor QDs. Functionalized QDs, including CdSe/ZnS, CdSe/CdS core/shell and PbS QDs, have been prepared at high concentration up to 10−4 M in homogeneous media, i.e. toluene. Fluorescence spectra and TEM images indicate that the modified QDs exhibit strong fluorescence and single particle features, respectively. Fluorescence images show that biocompatible CdSe/ZnS QDs are internalized into SK-BR-3 breast cancer cells after hydrophilic modification. Additionally, methacrylate-modified QDs have been used as monomers for radical polymerization.

Microwave-mediated nonaqueous synthesis of quantum dots at moderate temperature.

The use of microwave irradiation to accelerate both inorganic and organic chemical reactions has attracted widespread attention. Generally, microwave-mediated synthesis of quantum dots (QDs) has been conducted in aqueous solution. Here, using commercial diesel and glycerol as reaction medium, a microwave-mediated nonaqueous method toward CdSe QDs with size-tunable photoluminescent properties produces oleic-acid-protected QDs at moderate reaction temperatures of 50-140 degrees C, which are much lower than the current temperature necessary for the synthesis of CdSe QDs in organic solvents. The appropriate condition optimization for high-quality CdSe QDs shows that different sizes of CdSe QDs with emission wavelengths between 450 and 600 nm have been synthesized through varying time, temperature, feed ratio, and reaction medium.

PbS Quantum Dots for Near-Infrared Fluorescence Imaging

In this phantom-based study, we assessed the imaging potential of lead sulfide (PbS) near-infrared quantum dots (QDs) as novel contrast agents for deep tissue fluorescence imaging applications.