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The use of targeted drug delivery systems, including those based on selective absorption by certain receptors on the surface of the target cell, can lead to a decrease in the minimum effective dose and the accompanying toxicity of the drug, as well as an increase in therapeutic efficacy. A fullerene C60 conjugate (FA-PVP-C60) with polyvinylpyrrolidone (PVP) as a biocompatible spacer and folic acid (FA) as a targeting ligand for tumor cells with increased expression of folate receptors (FR) was obtained. Using 13C NMR spectroscopy, FT-IR, UV-Vis spectrometry, fluorometry and thermal analysis, the formation of the conjugate was confirmed and the nature of the binding of its components was established. The average particle sizes of the conjugate in aqueous solutions and cell culture medium were determined using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). The FA-PVP-C60 showed antiradical activity against •DPPH, •OH and O2•−, but at the same time, it was shown to generate 1O2. It was found that the conjugate in the studied concentration range (up to 200 μg/mL) is non-toxic in vitro and does not affect the cell cycle. To confirm the ability of the conjugate to selectively accumulate through folate-mediated endocytosis, its uptake into cells was analyzed by flow cytometry and confocal microscopy. It was shown that the conjugate is less absorbed by A549 cells with low FR expression than by HeLa, which has a high level of expression of this receptor. [ABSTRACT FROM AUTHOR]

The paper studies the influence of arc welding technological processes on the resistance of welded joints of sparcely-alloyed weathering 06g2BDP steel to cold and hot cracking and brittle and fatigue fracture. with the help of the Implant method and using the technological tekken sample, the conditions for cold cracking were evaluated and the methods of their elimination were recommended. It is shown that with the use of mechanized welding in shielding gases, solid-section and flux-cored wires provide high technological strength of welded joints in terms of hot cracking in a wide range of welding modes. On the other hand, when using coated electrodes, this range is narrowed, and at Vdef ≥ 20 mm/min, joints are prone to the formation of this defect. the results of studies on the evaluation of welded joint resistance to brittle fracture indicate high values of the stress intensity factor KQ for both the weld and HAZ metal. The endurance limit of T-joints when tested by cyclic loading was determined, which is [σ]-1 = 35 MPa. [ABSTRACT FROM AUTHOR]