Most radiological methods for examining the body, such as magnetic resonance therapy, radiography, ultrasound diagnostics, and many others demand the use of contrast agents. The existing contrast agents are imperfect and require further improvement. A special place among contrast agents is occupied by specific contrast agents, which allow targeted contrasting through the use of special ligands (for example, folic acid). In this work, we describe the preparation of stable gadolinium chelates with carbon nanostructures, which exhibit bright fluorescence and contain folic acid in their structure, available for binding to receptors. This opens up the possibility of using such structures for targeted contrast enhancement, as well as for local visualization of cancer cells and tissues.
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.
In this article, we have demonstrated the promising separation methods for hydrothermally obtained fluorescent molecule formed from citric acid and 1,2 – ethylenediamine. This fluorophore is a derivative of citrazinic acid and is known as a 1,2,3,5-tetrahydro-5-oxo-imidazo[1,2-a]pyridine-7-carboxylic acid (IPCA). Gel electrophoresis and dialysis were applied for the extraction the fluorophore from start materials. IPCA molecule has strong absorption at 350 nm and luminescence at 450 nm with a high quantum yield of around 85±5%. The structure of the fluorophore and polymer-like structures was researched by spectrophotometry, spectrofluorimetry, IR and NMR spectroscopy.
On the basis of "green chemistry" a simple, fast and effective synthetic method for producing photoluminescent carbon nanostructures was developed. The use of CaCO3 microparticles as microreactors makes it possible to use aqueous solutions for synthesis in a microwave oven. Microwave synthesis allows to get СNS quickly and without any complex multi-stage procedures. When comparing two syntheses (microwave and hydrothermal) to obtain photoluminescent carbon nanostructures under conditions of spatial limitation, they showed similar results. This allows the use of microwave synthesis as an alternative to obtain СNS and reduce the synthesis time to 30-60 minutes.
In this paper we report a synthesis of bifunctional material. Dual magnetic and fluorescent inorganic nanoparticles, providing the ability of control by a magnetic field and a high MRI contrast along with strong photoluminescence, are widely used in biology and medicine. The current work is aimed to the combination of magnetic and luminescence properties in one nanocomposite that would be enable the engineering of unique multifunctional nanoscale devices. We studied the methods of synthesis of bifunctional nanoparticles based on luminescent luminescent carbon nanostructures and Fe3O4 nanoparticles, stabilized by ethylenediamine and citric acid.
In this article we report an effective hydrothermal synthesis of bright-emissive nanoparticles from citric acid and ethylenediamine. Also, we demonstrate methods for separation of carbon nanoparticles such as high speed centrifugation and size-exclusion liquid chromatography. These nanoparticles due to their high quantum yield can be used as markers for biological tissues, liquids and cells.
In this paper, we show a low temperature normal pressure synthesis of a blue emissive organic fluorophore. The organic fluorophore molecule - 1, 2, 3, 5-tetrahydro-5-oxo-imidazo [1, 2-a] pyridine-7-carboxylic acid (IPCA) - consists of derivatives of imidazole and benzoic rings with a carboxylic group. The molecule has a strong emission maximum at around 450 nm when excitation of 350 nm us used and is correlated with PL spectra of carbon nanoparticles. The quantum yield was found to be relatively high: around 55%. IPCA luminescent properties are similar to the reported for some carbon nanostructures, obtained via hydrothermal synthesis from citric acid and ethylenediamine.
Carbon nanoparticles (CNPs) attract a lot of interest because of their numerous unique properties. The advantage of photoluminescent CNPs is the simplicity of synthesis and surface modification, photostability and low cytotoxicity. In connection with the variety of methods of synthesis and the possibility of changing the initial materials, it is expedient to study the factors that affect the properties of the obtained particles. Recently, much attention has been paid to CNPs based on citric acid and ethylenediamine. This is due to the fact that such particles have a high quantum yield and can be an alternative of semiconductor quantum dots. In this work, we report the influence of the form of the diamine and the pH of the CNPs solutions on the photoluminescent properties. We also studied the stability of CNPs diluted solutions in time. As a result of the work, we determined that the optimal pH of CNPs solutions are close to neutral, which makes it possible to use the CNPs in biological objects.
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