Scattering of the near field of an electric dipole by a single-wall carbon nanotube

The use of carbon nanotubes as optical probes for scanning near-field optical microscopy requires an understanding of their near-field response. As a first step in this direction, we investigated the lateral resolution of a carbon nanotube tip with respect to an ideal electric dipole representing an elementary detected object. A Fredholm integral equation of the first kind was formulated for the surface electric current density induced on a single-wall carbon nanotube (SWNT) by the electromagnetic field due to an arbitrarily oriented electric dipole located outside the SWNT. The response of the SWNT to the near field of a source electric dipole can be classified into two types, because surface-wave propagation occurs with (i) low damping at frequencies less than ~ 200-250 THz and (ii) high damping at higher frequencies. The interaction between the source electric dipole and the SWNT depends critically on their relative location and relative orientation, and shows evidence of the geometrical resonances of the SWNT in the low-frequency regime. These resonances disappear when the relaxation time of the SWNT is sufficiently low. The far-field radiation intensity is much higher when the source electric dipole is placed near an edge of SWNT than at the centroid of the SWNT. The use of an SWNT tip in scattering-type scanning near-field optical microscopy can deliver a resolution less than ~ 20 nm. Moreover, our study shows that the relative orientation and distance between the SWNT and the nanoscale dipole source can be detected.Comment: 23 pages, 16 figure

The Drug-Initiated Method: A Convenient Approach for the Synthesis of Efficient Polymer Prodrug Nanoparticles.

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Characterisation of new substrate specificities of Escherichia coli and Saccharomyces cerevisiae AP endonucleases

Despite the progress in understanding the base excision repair (BER) pathway it is still unclear why known mutants deficient in DNA glycosylases that remove oxidised bases are not sensitive to oxidising agents. One of the back-up repair pathways for oxidative DNA damage is the nucleotide incision repair (NIR) pathway initiated by two homologous AP endonucleases: the Nfo protein from Escherichia coli and Apn1 protein from Saccharomyces cerevisiae. These endonucleases nick oxidatively damaged DNA in a DNA glycosylase-independent manner, providing the correct ends for DNA synthesis coupled to repair of the remaining 5′-dangling nucleotide. NIR provides an advantage compared to DNA glycosylase-mediated BER, because AP sites, very toxic DNA glycosylase products, do not form. Here, for the first time, we have characterised the substrate specificity of the Apn1 protein towards 5,6-dihydropyrimidine, 5-hydroxy-2′-deoxyuridine and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine deoxynucleotide. Detailed kinetic comparisons of Nfo, Apn1 and various DNA glycosylases using different DNA substrates were made. The apparent K(m) and k(cat)/K(m) values of the reactions suggest that in vitro DNA glycosylase/AP lyase is somewhat more efficient than the AP endonuclease. However, in vivo, using cell-free extracts from paraquat-induced E.coli and from S.cerevisiae, we show that NIR is one of the major pathways for repair of oxidative DNA base damage

Polymer prodrug nanoparticles based on naturally occurring isoprenoid for anticancer therapy

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Efficient “green” encapsulation of a highly hydrophilic anticancer drug in metal–organic framework nanoparticles

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Formation of osteoconductive biograft with bioorganic scaffold, human mesenchymal stromal cells, and platelet-rich plasma with its evaluation in vitro

Background: Complex graft bioengineering is an actual topic in bone defects’ repair. For those, different scaffolds may be seeded with mesenchymal stromal cells and growth / differentiation factors. The natural role of platelet factors in reparative processes justifies the possibility of its usage for mesenchymal stromal cell proliferation and differentiation into osteoblasts in vitro in terms of the scaffold-based bioengineering. To develop and evaluate in vitro biocompatibility and osteoconductivity of a complex biograft based on a bioorganic scaffold seeded with human bone marrow mesenchymal stromal cells and saturated with growth and differentiation factors of allogeneic platelet-rich plasma. Results: The properties of viability and adhesion of human bone marrow mesenchymal stromal cells in four types of bioorganic scaffolds were evaluated with biochemical and immunomorphological methods. Scaffold with the least cytotoxicity was used as a basis for complex biograft formation, so as a carrier for cells and platelet-derived factors. Then, cell proliferation activity and osteogenic differentiation were estimated with biochemical, morphological, histochemical and molecular-biological methods. The study showed high viability of cells in all bioorganic scaffolds but the least cytotoxicity was the one based on xenogeneic collagen sponge. We also found that allogeneic platelet-rich plasma positively affects the proliferation and osteogenic differentiation of bone marrow mesenchymal stromal cells in a complex biograft in vitro. Conclusions: The properties of the developed complex biograft characterize its biocompatibility and osteoconductivity and make it potentially suitable for regenerative medicine, particularly for reconstructive surgery of bone defects.How to cite: Danilkovich NN, Kosmacheva SM, Ionova AG, et al. Formation of osteoconductive biograft with bioorganic scaffold, human mesenchymal stromal cells, and platelet rich plasma with its evaluationin vitro. Electron J Biotechnol 2024;69. https://doi.org/10.1016/j.ejbt.2024.01.004

Effects of Silencing the RET/PTC1 Oncogene in Papillary Thyroid Carcinoma by siRNA-Squalene Nanoparticles With and Without Fusogenic Companion GALA-Cholesterol

International audienc

Polymer Prodrug Nanoparticles Based on Naturally Occurring Isoprenoid for Anticancer Therapy

The synthesis of a novel class of polymer prodrug nanoparticles with anticancer activity is reported by using squalene, a naturally occurring isoprenoid, as a building block by the reversible addition–fragmentation (RAFT) technique. The RAFT agent was functionalized by gemcitabine (Gem) as anticancer drug, and the polymerization of squalenyl-methacrylate (SqMA) led to well-defined macromolecular prodrugs comprising one Gem at the extremity of each polymer chain. The amphiphilic nature of the resulting Gem–PSqMA conjugates allowed them to self-assemble into long-term stable and narrowly dispersed nanoparticles with significant anticancer activity in vitro on various cancer cell lines. To confer stealth properties on these nanoparticles, their PEGylation was successfully performed, as confirmed by X-ray photoelectron spectroscopy (XPS) and complement activation assay. It was also shown that the PEGylated nanoparticles could be internalized in cancer cells to a greater extent than their non-PEGylated counterparts

Intravenous delivery of anti-RhoA siRNA loaded in nanoparticles of chitosan in mice: safety and efficacy in xenografted breast cancer.

International audienc