Alloyed quantum dots (QDs) are luminescent semiconductor nanocrystals, which are promising materials in various fields of science and technology, including in bioanalysis. The key requirement for alloyed QDs in polar solutions analysis is hydrophilicity. The modification with dihydrolipoic acid (DHLA) makes it possible to increase the alloyed QDs colloidal stability in a polar medium while retaining the advantages of nanoparticles of this structure, and also allows further electrostatic self-assembly of alloyed QDs with antibodies. The article describes the DHLA-modification of the alloyed QDs composition CdxZn1-xSeyS1-y / ZnS using 2-mercaptoethanol (BME) as an additional hydrophilizing agent. The effect of hydrophilization conditions on the following modified properties alloyed QDs was studied: photoluminescence quantum yield (PLQY), width peak at half maximum (FWHM), luminescence peak position, colloidal stability during long-term storage. The search for the optimal ratio of hydrophilizing agents DHLA:BME was carried out, at which the advantages of the biligand shell would be maximally realized. The methods presented in this work make it possible to obtain alloyed QDs with a high PLQY (about 65%) and a long stability period (more than 3 months).
Alloyed quantum dots (QDs) are the popular material for the fabrication of the light-emitting diodes because of their optical parameters advantages. One of the most interesting features peculiar to this QDs class is the ability to controlled size-independent emission peak tuning via compound amounts changing. The same advantages can be valuable in bioanalytical methods and sensor systems development. Facile one-pot synthesis of the bright quaternary alloyed QDs made by CdxZn1-xSeyS1-y/ZnS semiconductor composition with narrow (FWHM < 26 nm) emission peak (548 nm) and photoluminescence quantum yield (PLQY) up to 50% was described. Obtained QDs were stabilized in water by the dihydrolipoic acid (DHLA) ligand exchange approach with insignificant PLQY loss relative initial (16%) and great colloidal stability period (6 months). This article summarizes the easiest ways of the alloyed QDs synthesis and subsequent hydrophilization for the potential simplification of their large-amounts manufacturing procedure.
We demonstrate a one-pot synthesis of CdSeZnS/ZnS alloyed blue (482 nm) and green (526 nm) quantum dots in organic solvents. During the formation of core/shell quantum dots (QDs), a blue-shift was observed after coating with ZnS shell. A wavelength tuning of alloyed QDs emission is obtained by the different ratios of Se-precursor in the cores. Silica surface was formed to make water-soluble alloyed QDs. The alloyed QDs were characterized by absorbance and photoluminescence (PL) spectroscopy and PL quantum yield.
Nowadays semiconductor quantum dots (QDs) is a popular luminescent material for different kinds of bioapplications. Core-shell CdSe/ZnS QDs obtained by the high-temperature synthesis are traditional luminescent nanocrystals with high quantum yield and narrow emission peak. But this type of QDs must be hydrophilized before their use in a water or biological environment. The goal of our work was the comparison of hydrophilized QDs properties, obtained from one initial sample using two different hydrophilization methods. Core-shell type QDs with CdSe/ZnS semiconductors composition was synthesized and hydrophilized by two ligand exchange methods: silanization and coating with dihydrolipoic acid (DHLA). Quantum yield, size and colloidal stability of the nanoparticles obtained via both methods were investigated. The collected data allows making the conclusions about perspectives to use the described methods in different bioapplications.