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Background and Objectives: In recent years, the attention of the scientific community has been attracted by cerium(IV) oxide nanoparticles (CeO2 NPs), which demonstrate great potential for use in biomedicine due to their unique biological properties such as antioxidant and antibacterial activity. The development of biomaterials that combine the properties of polymers and the unique characteristics of CeO2 NPs opens up new horizons for applications in biomedicine. A thin layer of polymers preserves the catalytic activity of cerium oxide without blocking the path of electronic charge transfer on the surface of nanoparticles. The relevance of the development of CeO2 NPs with a polymer shell lies in the fact that polymers can bind to various medicinal and bioactive substances, becoming drug carriers. This work describes the preparation of CeO2 NPs with various polymers in order to study how the composition and structure of the polymer affect the size and charge of the resulting nanoparticles. The variability of the properties of CeO2 NPs will make it possible to test them for the encapsulation of other substances, including drugs, in order to identify optimal polymers. Materials and Methods: Cerium(III) nitrate hexahydrate Ce(NO3)3 · 6H2O was used as a precursor for the synthesis of CeO2 NPs. Four different polymers were used for the syntheses: polyacrylic acid (PAA), polyethylene glycol (PEG), poly(isobutylene-alt-maleic anhydride) (PIMA). The synthesis was carried out in ammonium hydroxide (28–30%). CeO2 NPs with a polymer shell were obtained by chemical deposition. Polymer solutions were prepared and mixed with a 1 M solution of Ce(NO3)3. With continuous stirring, the mixture was added to the ammonium hydroxide solution, after which ethanol was added and left under stirring for 24 hours at room temperature. Results: We have presented the synthesis of cerium oxide nanoparticles in the presence of polymers of various compositions and molecular weights to study their effect on the structure and size of nanoparticles. During the synthesis, it has been revealed that the optimal concentration of cerium(III) nitrate for syntheses is 1 M. The influence of the environment on the possible agglomeration of nanoparticles during purification and further storage has been studied. The best media for storing and purifying nanoparticles are water and phosphate-buffered saline. The size and morphology of the resulting polymer-coated CeO2 NPs have been studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS). TEM images show nanocrystals measuring about 10 nm in all four samples. SEM images show the presence of particles with a size of about 20–30 nm in all four samples. DLS analysis has shown that the smallest particles were formed with polyacrylic acid and poly(isobutylene-alt-maleic anhydride). Conclusions: The results of the study have demonstrated that for the synthesis of CeO2 NPs with a polymer coating it is better to use PAA and PIMA polymers since smaller particles are formed. It has been found that it is optimal to use 1 M Ce(NO3)3 for syntheses, and the best media for purification and storage of CeO2 NPs are water and FSB.

Background and Objectives: Polyamidoamine dendrimers (PAMAM) are nanoscale monodisperse compounds with a multifunctional terminal surface. Structural features of PAMAM, such as a nanosize of high homogeneity, highly developed terminal surface and cavities in the structure open up wide possibilities for their application. The most promising use of PAMAM is for biomedical purposes, in particular for the targeted drug delivery (for example, anticancer drugs). The interaction of PAMAM with target cells can be assessed using fluorescent imaging. This suggests the preliminary modification of PAMAM with various fluorescent molecules or the development of approaches to increase the intrinsic fluorescence of PAMAM. Materials and Methods: In this paper, we will consider a one-step modification of PAMAM based on the double cyclization reaction of PAMAM terminal groups and citric acid. Two approaches are chosen for modification: hydrothermal and boiling methods. The methods of optical spectroscopy and dynamic light scattering will be used as the main research tools. The methods used make it possible to determine the efficiency of fluorophore formation under given conditions. Results: In this work, we have proposed and implemented a one-step modification of PAMAM with a bright blue fluorophore (1,2,3,5-tetrahydro-5-oxo-imidazo[1,2-a] pyridine-7-carboxylic acid, IPCA), which is formed by a double cyclization reaction between citric acid and terminal ethylenediamine fragments of PAMAM. It has been shown that as a result of modification the hydrodynamic diameter of PAMAM does not change, the fluorescence intensity increases significantly (the quantum yield increases from < 1 to 28%), ζ-potential changes from 42 ± 5 to −24 ± 4 mV. Conclusion: Reaction of PAMAM and citric acid leads to the appearance of bright-blue fluorescence, which is significantly higher than the intrinsic fluorescence of PAMAM. A combination of bright fluorescence and a multifunctional terminal surface make it possible to further use the obtained structures for biovisualization.

The fluorescent properties of products obtained by the hydrothermal treatment of organic raw materials are of great interest. Such products are usually colloidal stability in water, have low cytotoxicity, and high photostability. One of their advantages is a wide choice of starting materials and the relative simplicity of synthesis. The use of folic acid as a precursor for fluorescent nanostructures opens up the possibility of targeted imaging. This article shows a one-step synthesis of fluorescent nanostructures from folic acid and citrates. The effect of citrate concentration in the range from 0.05 to 2 mol/l on the optical properties of the synthesized structures is also studied.