Quantum dots (QDs) are modern nanoparticles with a wide potential for use in medicine, bioanalysis, as well as in optics and energetics. Different types of QDs can be produced depending on their synthesis method. QDs formed by semiconductor components able to mutual solid-solution formation named alloyed. This type of QDs has a high quantum yield and narrow emission peak but less chemical stability relative to core-shell type QDs. Better core-shell QDs stability explains by the additional surface shell covering. This approach can be applied to the alloyed QDs also. One-step hightemperature organometallic procedure is excellent in this regard due to its simplicity and consistency in the synthesis. However, QDs which obtained in this way are hydrophobic and do not dissolve in polar solutions such as water. Hydrophilization is used to convert QDs from a hydrophobic to a hydrophilic state. It was found that when hydrophilizing with β-mercaptoethanol, the quantum yield (QY) significantly increases, although when hydrophilizing with other ligands, it is just a decrease in the quantum yield that appears. This article investigates the process of hydrophilization of core-shell alloyed QDs in which an increase in QY is observed. For this, the effect on the optical properties of the amount of the hydrophilizing agent, long-term storage at room and low temperatures, and the effect of pH on hydrophilized QDs are considered.
Quantum dots and gold nanoparticles are among the most common labels for immunochemical analysis. Methods for conjugating nanoparticles with antibodies, proteins and antigens are required in almost any test method based on antibody-antigen interaction. We examined particles of various sizes and functionalities for conjugation protocols. Physical adsorption methods for gold nanoparticles and quantum dots with epoxy and carboxyl groups on the surface for chemical reaction were considered.
In this paper, we report the synthesis of hydrophilic luminescent quantum dots (QDs) of the core/shell structure using two approaches: high-temperature organic synthesis of CdZnSeS/ZnS and aqueous synthesis of AgInS/ZnS. Dihydrolipoic and thioglycolic acids have been used as surface ligands to impart hydrophilic properties. The influence of whole blood and serum on the optical properties of both types of QDs was evaluated for their application in blood analysis. It has been shown that AgInS/ZnS QDs with emission in the red spectral region (λPL = 638 nm) remained the most stable in whole blood samples and its optimal dilutions (up to 1:100, inclusive). Whereas CdZnSeS/ZnS fluorescent in the green region of the spectrum (λPL = 530 nm) showed the best signal of fluorescence (PL) intensity in blood serum samples.
Polyelectrolyte microcapsules are one of the most successful developments in the direction of target drug delivery. Nevertheless, to encapsulate low molecular weight compounds and to deliver the targeted drugs it is necessary to modify the surface of the microcapsules. Silica nanostructures obtained as result of hydrolysis of (3-Aminopropyl)- triethoxysilane (APTES) were used for the modification of the microcapsules. This material shows no toxic effect on cells and is capable of biodegradation. Amino-groups in the structure of APTES make it possible for further direct bioconjugation.
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