Yu. V. Kuznetsova

Synthesis of cadmium sulfide CdS nanoparticles in a silicate glass matrix

Cadmium sulfide (CdS) nanoparticles have been synthesized in a silicate glass matrix containing ZnO additions. Annealing conditions in the temperature range of the glass transition have been shown to determine the final size of the CdS nanoparticles. The particle size, in turn, influences the optical properties, color, and fundamental absorption edge of the glass. The present results demonstrate that, with increasing CdS nanoparticle size, the absorption edge of the glass experiences a redshift from 330 to 530 nm and its luminescence peak shifts from 450 to 750 nm.

Size and zeta potential of CdS nanoparticles in stable aqueous solution of EDTA and NaCl

We have studied the effect of disodium EDTA concentration on the size and zeta potential of CdS nanoparticles in a stable aqueous solution. Measurement results demonstrate that the colloidal solution remains stable at initial Cd2+ and S2− concentrations of 8 mM and initial EDTA concentrations in the range 3.2 to 16 mM. The reactant mixing sequence is shown to influence the ionic state of EDTA in solution, which in turn influences the stabilization mechanism of the CdS nanoparticles. At pH 3, we observe the formation of protonated chelates such as [CdHY]−, which may form a [-S-Cd-EDTA] ternary complex with the surface of a nanoparticle, thereby ensuring stability of the colloidal solution at a twofold excess of EDTA. Analysis of the nanoparticle size distribution evaluated by dynamic light scattering measurements indicates that the minimum hydrodynamic diameter of the nanoparticles is 10 ± 3 nm. The corresponding zeta potential is about −20 mV.

Influence of the size and charge of nonstoichiometric silver sulfide nanoparticles on their interaction with blood cells

Silver sulfide (Ag2S) nanoparticles synthesized using different precursors have been characterized by dynamic light scattering measurements and high-resolution transmission electron microscopy. In addition to Ag2S nanoparticles, we have detected Ag2S/Ag heterostructures. Using optical microscopy, we have examined interaction of the nanoparticles with red cells of peripheral blood. The results of the interaction have been shown to depend on the particle size and charge. A red cell solution containing large, negatively charged particles coagulated, whereas small, positively charged Ag2S nanoparticles were concentrated around red cells.

Synthesis of a stable colloidal solution of PbS nanoparticles

A method has been proposed for the synthesis of stable colloidal solutions of lead sulfide nanoparticles from aqueous lead acetate and sodium sulfide solutions. The citrate ion and ethylenediaminetetraacetic acid were used as complexing agents to stabilize the solution. The solutions obtained were shown to remain stable at room temperature for at least 30 days from the instant of synthesis, depending on the initial reactant concentration. According to X-ray diffraction and dynamic light scattering data, the stability and coagulation of the nanoparticles in solution were influenced by the lead and sulfur concentration, the presence of complexing agents, and the quantitative relation between the lead and complexing agent ions in solution. Optical absorption measurements for the colloidal PbS nanoparticle solutions showed that their absorbance was a nonlinear function of reactant concentration.

Zeta Potential, Size, and Semiconductor Properties of Zinc Sulfide Nanoparticles in a Stable Aqueous Colloid Solution

A stable aqueous colloid solution of zinc sulfide (ZnS) nanoparticles was obtained by chemical condensation using ethylenediaminetetraacetic acid disodium salt. The mechanism of prolonged aggregative stability of solution at pH 7–8 with ~7-nm nanoparticles was determined as a result of the zeta potential measurements by dynamic light scattering. The blue and red shifts of the fundamental absorption edge of zinc sulfide semiconductor nanoparticles associated with the small size of nanoparticles and the defective state of their surface were found by optical spectrophotometry.

Synthesis and optical properties of glass with cadmium sulfide nanoparticles

A new approach to the synthesis of silicate glass with cadmium sulfide (CdS) nanoparticles has been developed. It has been demonstrated that replacement of cadmium sulfide with cadmium oxide and zinc sulfide used as sources of cadmium and sulfur allows a substantial reduction of sulfur volatilization during the melting. The produced samples have been investigated by the methods of spectrophotometry in the ultraviolet and visible ranges of the optical range. Thermal treatment of the samples at temperatures exceeding the glass formation point initiates the growth of CdS nanoparticles, which results in the increase of their average size from 3 to 5.2 nm and a significant shift of the fundamental absorption edge to the longer wavelength range from 380 to 480 nm.

The design of hybrid materials based on magnetic Fe3O4 nanoparticles and luminescent CdS nanoparticles for cell visualization

Hybrid nanoparticles based on Fe3O4 and CdS combining magnetic and luminescence properties were synthesized. The possibility of visualization of various cells by 3-mercaptopropylsilane-modified CdS nanoparticles and hybrid nanoparticles based on them using a confocal microscope was demonstrated. The synthesized materials did not show a clear-cut cytotoxicity.

Formation of CdS nanoparticles in the matrix of silicate glass and its optical properties

CdS nanoparticles of an average diameter of ~2.7 nm have been synthesized in silicate glass by two stage heat treatment. As was demonstrated using the methods of spectrophotometry and luminescence in the ultraviolet and visible optical ranges, semiconductor phase nuclei were formed at the first stage of thermal treatment, and they grew at the second stage. The image of the spatial distribution of CdS nanoparticles in the glass network has been obtained by computer simulation. The calculated pair distribution function revealed that the average distance between nanoparticles was ~15 nm, which appears sufficient to isolate them from each other in the dielectric matrix and to ensure reliable confinement of electrons inside each nanoparticle.

Synthesis of hybrid nanoparticles based on magnetic Fe3O4 nanoparticles and luminescent CdS nanoparticles

A new approach to the synthesis of hybrid nanoparticles based on magnetic Fe3O4 nanoparticles and CdS quantum dots, combining magnetic and luminescence properties, has been suggested. Conditions for preparation of their stable aqueous suspensions have been found, and their optical properties have been studied. Nanocomposites produced at the molar ratio Fe3O4: CdS = 5: 1, which exhibited the luminescence properties) and gave stable aqueous suspensions, have turned out to be most promising. The results are evidence that the synthesized nanoparticles can be used for the development of visualizing agents for in vitro biomedical research.

Zeta Potential and Hydrodynamic Radii of Silver Sulfide Nanoparticles in a Colloidal Solution with Mercaptopropylsilane

The dependence of the zeta potential and hydrodynamic radii of silver sulfide nanoparticles (Ag2S) in an aqueous colloidal solution on the concentration of stabilizer 3-mercaptopropyltrimethoxysilane (MPS) is determined. A model for the structure of a surface layer of Ag2S nanoparticles coated with MPS is proposed that explains the observed dependence and the extrema on it. It is found that the values of the zeta potential and the hydrodynamic radii of the Ag2S nanoparticles depend substantially on the means of creating an excess of silver ions in the solution. This dependence is explained by the dynamics of the formation of a stabilizer layer on the surface of nanoparticles.