Synthesis of AS1411-aptamer-conjugated CdTe quantum dots with high fluorescence strength for probe labeling tumor cells

In this paper, we report microwave-assisted, one-stage synthesis of high-quality functionalized water-soluble cadmium telluride (CdTe) quantum dots (QDs). By selecting sodium tellurite as the Te source, cadmium chloride as the Cd source, mercaptosuccinic acid (MSA) as the capping agent, and a borate-acetic acid buffer solution with a pH range of 5-8, CdTe nanocrystals with four colors (blue to orange) were conveniently prepared at 100 °C under microwave irradiation in less than one hour (reaction time: 10-60 min). The influence of parameters such as the pH, Cd:Te molar ratio, and reaction time on the emission range and quantum yield percentage (QY%) was investigated. The structures and compositions of the prepared CdTe QDs were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, selective area electron diffraction, and X-ray powder diffraction experiments. The formation mechanism of the QDs is discussed in this paper. Furthermore, AS1141-aptamer-conjugated CdTe QDs in the U87MG glioblastoma cell line were assessed with a fluorescence microscope. The obtained results showed that the best conditions for obtaining a high QY of approximately 87% are a pH of 6, a Cd:Te molar ratio of 5:1, and a 30-min reaction time at 100 °C under microwave irradiation. The results showed that AS1141-aptamer-conjugated CdTe QDs could enter tumor cells efficiently. It could be concluded that a facile high-fluorescence-strength QD conjugated with a DNA aptamer, AS1411, which can recognize the extracellular matrix protein nucleolin, can specifically target U87MG human glioblastoma cells. The qualified AS1411-aptamer-conjugated QDs prepared in this study showed excellent capabilities as nanoprobes for cancer targeting and molecular imaging.

Copper Nanoparticles: Synthetic Strategies, Properties and Multifunctional Application

Copper nanoparticles received much attention due to its high electrical conductivity, high melting point, low electrochemical migration behavior and low cost. Top down (physical methods) and bottom up (chemical and biological) approaches adopted for the synthesis of copper nanoparticles are reported. The property of copper nanoparticles mainly depends on the synthesis route and their process parameters. The influence of process parameters on the morphology, growth and yield of the nanoparticles by adopting various synthesis methods are discussed in detail. From the earlier reports, it is proved that electrochemical and chemical reduction method have received much higher attention due to their simple operation, low cost, faster reaction rate, high yield, environment friendly and low energy consumption. The characterization techniques, advantages and limitations of each synthesis methods are also discussed. The extensive applications of copper nanoparticles in various fields are also highlighted.

CuGaS2 hollow spheres from Ga-CuS core-shell nanoparticles

A liquid gallium emulsion was prepared as a starting material using ultrasound treatment in ethylene glycol. Core-shell particles of Ga@CuS were successfully synthesized by deposition of a CuS layer on gallium droplets through sonochemical deposition of copper ions and thiourea in an alcohol media. The core and shell of Ga@CuS products were composed of amorphous gallium metal and covellite phase CuS, which transformed into chalcopyrite CuGaS2 hollow spheres after sulfurization at 450°C, which was the lowest crystallization temperature. The formation of hollow nanostructures was ascribed to the Kirkendall mechanism, in which liquid gallium particles play an important role as reactive templates. In conclusion, we obtained CuGaS2 hollow spheres with a 430 nm outer diameter and 120 nm shell thickness that had the same crystal structure and electrical properties as bulk CuGaS2.

Large‐Scale, Surfactant‐Free Solution Syntheses of Cu(In,Ga)(S,Se)2 Nanocrystals for Thin Film Solar Cells

Large‐scale (as much as 200 g in a batch) and surfactant‐free syntheses of the CuInxGa1–xSe2 and the CuInxGa1–xS2 nanoparticles were investigated by employing a sonochemical process under ambient conditions. This synthetic approach eliminates the need for organic stabilizers, which may act as an insulator in the final device, and reduces the number of reaction steps for synthesis of high‐quality CISe nanocrystals. We also demonstrate the solution‐based fabrication of the thin film photovoltaic devices with a conversion efficiency of 2.62 % by using nanocrystal‐based inks. The device was fabricated with 2 μm of a CIGS absorber layer on Mo‐coated soda lime glass, 70 nm of a chemical‐bath‐deposited CdS layer, 100 nm of an intrinsic ZnO layer, followed by 800 nm of a Al‐doped ZnO layer. Finally, a patterned Ag (200 nm) grid was deposited on the top of the device. The current results offer a promising alternative for solution‐based CIGSe thin film solar cells, with a higher efficiency.