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.
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.
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.
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.
Photoluminescent (PL) properties of carbon-based nanomaterials obtained on the base of sodium dextran sulfate (DS) were compared. DS water solution, dry powder and co-precipitated inside pores of CaCO3 microparticles solution were thermally treated and clear difference between these materials was found. Effect of spatial restriction of CaCO3 pores showed itself in the identity of PL properties for material, obtained by thermal and hydrothermal treatment; in the absence of CaCO3 microparticles the PL spectra were quite different.
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