QUANTUM DOTS OF CADMIUM SULFIDE PRODUCED WITH THE USE OF PROTEINS-PORINS, CARRAGEANANS, CHITOSANS AND LIPOPOLOSACCHARIDES

Abstract

Quantum dots (QDs) are a new generation of fluorochromes with significant advantages over traditional organic dyes. QDs based on CdS are promising materials for optics, optoelectronics, biology, and medicine. QDs in the form of colloidal solutions are of great scientific and practical interest. CdS quantum dots were synthesized by chemical condensation in an aqueous solution using Yersinia pseudotuberculosis porin proteins, positively (chitosan) and negatively (carrageenan, lipopolysaccharide) charged polysaccharides. The maxima of the emission spectra for all samples were 450 nm, which indicates the same QD size; is determined by the size of the "cells" of the grid matrix, which limit the size of the QD. It was shown that the fluorescence intensity of QDs synthesized in LPS solutions was two times higher than that of other samples. The fluorescence of the samples and the maxima of the emission spectra (450 nm) are preserved during intensive dialysis against buffers, which indicates the stability of QDs and the possibility of using the obtained labeled preparations. Keeping samples at pH 3 leads to a significant decrease in fluorescence, especially for acidic polysaccharides. Anionic oxygen of phosphate, hydroxyl groups of sugar, nitrogen atoms can interact with metal ions, which are precursors (precursors) for CdS nanocrystals. It was found that the interaction with porin-specific IgG leads to a significant change in the luminescence intensity of QD-porin samples. This is of interest from the point of view of chemical sensing and opens the prospect of using QD-labeled porin-based nanostructures as biosensors.