Electrospun Scaffolds Enriched with Nanoparticle-Associated DNA: General Properties, DNA Release and Cell Transfection.

Biomaterial-mediated, spatially localized gene delivery is important for the development of cell-populated scaffolds used in tissue engineering. Cells adhering to or penetrating into such a scaffold are to be transfected with a preloaded gene that induces the production of secreted proteins or cell reprogramming. In the present study, we produced silica nanoparticles-associated pDNA and electrospun scaffolds loaded with such nanoparticles, and studied the release of pDNA from scaffolds and cell-to-scaffold interactions in terms of cell viability and pDNA transfection efficacy. The pDNA-coated nanoparticles were characterized with dynamic light scattering and transmission electron microscopy. Particle sizes ranging from 56 to 78 nm were indicative of their potential for cell transfection. The scaffolds were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, stress-loading tests and interaction with HEK293T cells. It was found that the properties of materials and the pDNA released vary, depending on the scaffold's composition. The scaffolds loaded with pDNA-nanoparticles do not have a pronounced cytotoxic effect, and can be recommended for cell transfection. It was found that (pDNA-NPs) + PEI9-loaded scaffold demonstrates good potential for cell transfection. Thus, electrospun scaffolds suitable for the transfection of inhabiting cells are eligible for use in tissue engineering.

Preservation of Mechanical and Morphological Properties of Porcine Cardiac Outflow Vessels after Decellularization and Wet Storage.

Widely used storage methods, including freezing or chemical modification, preserve the sterility of biological tissues but degrade the mechanical properties of materials used to make heart valve prostheses. Therefore, wet storage remains the most optimal option for biomaterials. Three biocidal solutions (an antibiotic mixture, an octanediol-phenoxyethanol complex solution, and a glycerol-ethanol mixture) were studied for the storage of native and decellularized porcine aorta and pulmonary trunk. Subsequent mechanical testing and microstructural analysis showed a slight increase in the tensile strength of native and decellularized aorta in the longitudinal direction. Pulmonary trunk elongation increased 1.3-1.6 times in the longitudinal direction after decellularization only. The microstructures of the tested specimens showed no differences before and after wet storage. Thus, two months of wet storage of native and decellularized porcine aorta and pulmonary trunks does not significantly affect the strength and elastic properties of the material. The wet storage protocol using alcohol solutions of glycerol or octanediol-phenoxyethanol mixture may be intended for further fabrication of extracellular matrix for tissue-engineered biological heart valve prostheses.

Activated Carbon-Enriched Electrospun-Produced Scaffolds for Drug Delivery/Release in Biological Systems.

To vectorize drug delivery from electrospun-produced scaffolds, we introduce a thin outer drug retention layer produced by electrospinning from activated carbon nanoparticles (ACNs)-enriched polycaprolacton (PCL) suspension. Homogeneous or coaxial fibers filled with ACNs were produced by electrospinning from different PCL-based suspensions. Stable ACN suspensions were selected by sorting through solvents, stabilizers and auxiliary components. The ACN-enriched scaffolds produced were characterized for fiber diameter, porosity, pore size and mechanical properties. The scaffold structure was analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that ACNs were mainly coated with a polymer layer for both homogeneous and coaxial fibers. Drug binding and release from the scaffolds were tested using tritium-labeled sirolimus. We showed that the kinetics of sirolimus binding/release by ACN-enriched scaffolds was determined by the fiber composition and differed from that obtained with a free ACN. ACN-enriched scaffolds with coaxial and homogeneous fibers had a biocompatibility close to scaffold-free AC, as was shown by the cultivation of human gingival fibroblasts and umbilical vein cells on scaffolds. The data obtained demonstrated that ACN-enriched scaffolds had good physico-chemical properties and biocompatibility and, thus, could be used as a retaining layer for vectored drug delivery.

Effect of Sterilization Methods on Electrospun Scaffolds Produced from Blend of Polyurethane with Gelatin.

Fibrous polyurethane-based scaffolds have proven to be promising materials for the tissue engineering of implanted medical devices. Sterilization of such materials and medical devices is an absolutely essential step toward their medical application. In the presented work, we studied the effects of two sterilization methods (ethylene oxide treatment and electron beam irradiation) on the fibrous scaffolds produced from a polyurethane-gelatin blend. Scaffold structure and properties were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared spectroscopy (FTIR), a stress-loading test, and a cell viability test with human fibroblasts. Treatment of fibrous polyurethane-based materials with ethylene oxide caused significant changes in their structure (formation of glued-like structures, increase in fiber diameter, and decrease in pore size) and mechanical properties (20% growth of the tensile strength, 30% decline of the maximal elongation). All sterilization procedures did not induce any cytotoxic effects or impede the biocompatibility of scaffolds. The obtained data determined electron beam irradiation to be a recommended sterilization method for electrospun medical devices made from polyurethane-gelatin blends.

Activated Carbon for Drug Delivery from Composite Biomaterials: The Effect of Grinding on Sirolimus Binding and Release.

Activated carbon (AC) could be potentially useful as a drug carrier in fiber polymer scaffolds destined for prolonged drug delivery. To be introduced, AC must be ground into smaller-sized particles to be introduced in scaffolds, as most biocompatible scaffolds consist of fibers with a diameter of less than 1 µm. In this study, the adsorption of sirolimus (SRL) from phosphate-buffered saline (PBS) solution and blood plasma (BP) onto AC of AX-21 type, as well as the release of SRL from AC depending on its fragmentation, were studied. Two-stage grinding of the AC, first with a ball mill, and then with a bead mill, was performed. Grinding with a bead mill was performed either in water or in polyvinylpyrrolidone to prevent aggregation of AC particles. Dynamic light scattering and scanning electron microscopy (SEM) demonstrated that the size of the particles obtained after grinding with a ball mill was 100-10,000 nm, and after grinding with a bead mill, 100-300 nm. Adsorption in PBS was significantly higher than in BP for all fractions, and depended on SRL concentration. The fraction obtained after grinding with a ball mill showed maximal SRL adsorption, both in PBS and BP, and slow SRL release, in comparison with other fractions. The 100-300 nm AC fractions were able to adsorb and completely release SRL into BP, in contrast to other fractions, which strongly bound a significant amount of SRL. The data obtained are to be used for controlled SRL delivery, and thus in the modification of drug delivery in biological media.

Core-Shell Magnetoactive PHB/Gelatin/Magnetite Composite Electrospun Scaffolds for Biomedical Applications.

Novel hybrid magnetoactive composite scaffolds based on poly(3-hydroxybutyrate) (PHB), gelatin, and magnetite (Fe3O4) were fabricated by electrospinning. The morphology, structure, phase composition, and magnetic properties of composite scaffolds were studied. Fabrication procedures of PHB/gelatin and PHB/gelatin/Fe3O4 scaffolds resulted in the formation of both core-shell and ribbon-shaped structure of the fibers. In case of hybrid PHB/gelatin/Fe3O4 scaffolds submicron-sized Fe3O4 particles were observed in the surface layers of the fibers. The X-ray photoelectron spectroscopy results allowed the presence of gelatin on the fiber surface (N/C ratio-0.11) to be revealed. Incubation of the composite scaffolds in saline for 3 h decreased the amount of gelatin on the surface by more than ~75%. The differential scanning calorimetry results obtained for pure PHB scaffolds revealed a characteristic melting peak at 177.5 °C. The presence of gelatin in PHB/gelatin and PHB/gelatin/Fe3O4 scaffolds resulted in the decrease in melting temperature to 168-169 °C in comparison with pure PHB scaffolds due to the core-shell structure of the fibers. Hybrid scaffolds also demonstrated a decrease in crystallinity from 52.3% (PHB) to 16.9% (PHB/gelatin) and 9.2% (PHB/gelatin/Fe3O4). All the prepared scaffolds were non-toxic and saturation magnetization of the composite scaffolds with magnetite was 3.27 ± 0.22 emu/g, which makes them prospective candidates for usage in biomedical applications.

A Lipid-Coated Nanoconstruct Composed of Gold Nanoparticles Noncovalently Coated with Small Interfering RNA: Preparation, Purification and Characterization.

There is an urgent need to develop systems for nucleic acid delivery, especially for the creation of effective therapeutics against various diseases. We have previously shown the feasibility of efficient delivery of small interfering RNA by means of gold nanoparticle-based multilayer nanoconstructs (MLNCs) for suppressing reporter protein synthesis. The present work is aimed at improving the quality of preparations of desired MLNCs, and for this purpose, optimal conditions for their multistep fabrication were found. All steps of this process and MLNC purification were verified using dynamic light scattering, transmission electron microscopy, and UV-Vis spectroscopy. Factors influencing the efficiency of nanocomposite assembly, colloidal stability, and purification quality were identified. These data made it possible to optimize the fabrication of target MLNCs bearing small interfering RNA and to substantially improve end product quality via an increase in its homogeneity and a decrease in the amount of incomplete nanoconstructs. We believe that the proposed approaches and methods will be useful for researchers working with lipid nanoconstructs.

Assessment of Electrospun Pellethane-Based Scaffolds for Vascular Tissue Engineering.

We examined the physicochemical properties and the biocompatibility and hemocompatibility of electrospun 3D matrices produced using polyurethane Pellethane 2363-80A (Pel-80A) blends Pel-80A with gelatin or/and bivalirudin. Two layers of vascular grafts of 1.8 mm in diameter were manufactured and studied for hemocompatibility ex vivo and functioning in the infrarenal position of Wistar rat abdominal aorta in vivo (n = 18). Expanded polytetrafluoroethylene (ePTFE) vascular grafts of similar diameter were implanted as a control (n = 18). Scaffolds produced from Pel-80A with Gel showed high stiffness with a long proportional limit and limited influence of wetting on mechanical characteristics. The electrospun matrices with gelatin have moderate capacity to support cell adhesion and proliferation (~30-47%), whereas vascular grafts with bivalirudin in the inner layer have good hemocompatibility ex vivo. The introduction of bivalirudin into grafts inhibited platelet adhesion and does not lead to a change hemolysis and D-dimers concentration. Study in vivo indicates the advantages of Pel-80A grafts over ePTFE in terms of graft occlusion, calcification level, and blood velocity after 6 months of implantation. The thickness of neointima in Pel-80A-based grafts stabilizes after three months (41.84 ± 20.21 µm) and does not increase until six months, demonstrating potential for long-term functioning without stenosis and as a suitable candidate for subsequent preclinical studies in large animals.

Influence of Elongation of Paclitaxel-Eluting Electrospun-Produced Stent Coating on Paclitaxel Release and Transport through the Arterial Wall after Stenting.

It was previously shown that polycaprolactone (PCL)-based electrospun-produced paclitaxel (PTX)-enriched matrices exhibit long-term drug release kinetics and can be used as coatings for drug-eluting stents (DES). The installation of vascular stents involves a twofold increase in stent diameter and, therefore, an elongation of the matrices covering the stents, as well as the arterial wall in a stented area. We studied the influence of matrix elongation on its structure and PTX release using three different electrospun-produced matrices. The data obtained demonstrate that matrix elongation during stent installation does not lead to fiber breaks and does not interfere with the kinetics of PTX release. To study PTX diffusion through the expanded artery wall, stents coated with 5%PCL/10%HSA/3%DMSO/PTX and containing tritium-labeled PTX were installed into the freshly obtained iliac artery of a rabbit. The PTX passing through the artery wall was quantified using a scintillator ß-counter. The artery retained the PTX and decreased its release from the coating. The retention of PTX by the arterial wall was more efficient when incubated in blood plasma in comparison with PBS. The retention/accumulation of PTX by the arterial wall provides a prolonged drug release and allows for the reduction in the dose of the drugs in electrospun-produced stent coatings.

Ultrastructural Features of Gold Nanoparticles Interaction with HepG2 and HEK293 Cells in Monolayer and Spheroids.

Use of multicellular spheroids in studies of nanoparticles (NPs) has increased in the last decade, however details of NPs interaction with spheroids are poorly known. We synthesized AuNPs (12.0 ± 0.1 nm in diameter, transmission electron microscopy (TEM data) and covered them with bovine serum albumin (BSA) and polyethyleneimine (PEI). Values of hydrodynamic diameter were 17.4 ± 0.4; 35.9 ± 0.5 and ±125.9 ± 2.8 nm for AuNPs, AuBSA-NPs and AuPEI-NPs, and Z-potential (net charge) values were -33.6 ± 2.0; -35.7 ± 1.8 and 39.9 ± 1.3 mV, respectively. Spheroids of human hepatocarcinoma (HepG2) and human embryo kidney (HEK293) cells (Corning ® spheroid microplates CLS4515-5EA), and monolayers of these cell lines were incubated with all NPs for 15 min-4 h, and fixed in 4% paraformaldehyde solution. Samples were examined using transmission and scanning electron microscopy. HepG2 and HEK2893 spheroids showed tissue-specific features and contacted with culture medium by basal plasma membrane of the cells. HepG2 cells both in monolayer and spheroids did not uptake of the AuNPs, while AuBSA-NPs and AuPEI-NPs readily penetrated these cells. All studied NPs penetrated HEK293 cells in both monolayer and spheroids. Thus, two different cell cultures maintained a type of the interaction with NPs in monolayer and spheroid forms, which not depended on NPs Z-potential and size.

Vascular Stents Coated with Electrospun Drug-Eluting Material: Functioning in Rabbit Iliac Artery.

A stenting procedure aimed at blood flow restoration in stenosed arteries significantly improves the efficiency of vascular surgery. However, the current challenge is to prevent neointimal growth, which reduces the vessel lumen, in the stented segments in the long run. We tested in vivo drug-eluting coating applied by electrospinning to metal vascular stents to inhibit the overgrowth of neointimal cells via both the drug release and mechanical support of the vascular wall. The blend of polycaprolactone with human serum albumin and paclitaxel was used for stent coating by electrospinning. The drug-eluting stents (DESs) were placed using a balloon catheter to the rabbit common iliac artery for 1, 3, and 6 months. The blood flow rate was ultrasonically determined in vivo. After explantation, the stented arterial segment was visually and histologically examined. Any undesirable biological responses (rejection or hemodynamically significant stenosis) were unobservable in the experimental groups. DESs were less traumatic and induced weaker neointimal growth; over six months, the blood flow increased by 37% versus bare-metal stents, where it increased by at least double the rate. Thus, electrospun-coated DESs demonstrate considerable advantages over the bare-metal variants.

Sirolimus-Eluting Electrospun-Produced Matrices as Coatings for Vascular Stents: Dependence of Drug Release on Matrix Structure and Composition of the External Environment.

Although a number of drug-eluting coatings for vascular stents (VSs) have been developed and are in commercial use, more efficient stent coatings and drug delivery systems are needed. Sirolimus (SRL) is a clinically important drug with antiproliferative and immunosuppressive activities that is widely used for coating stents. Here, we characterized SRL-enriched matrices, intended for coating vascular stents, that were produced by electrospinning (ES) on a drum collector from a solution of polycaprolactone (PCL) and human serum albumin (HSA), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), dimethyl sulfoxide (DMSO), and SRL. The release of tritium-labeled SRL (3H-SRL) from matrices in phosphate-buffered saline (PBS) or human blood plasma (BP) was studied. The introduction of DMSO in the ES blend decreased SRL release. The use of BP significantly accelerated SRL release through binding with serum biomolecules. The exchange of PBS or BP after every time point also increased SRL release. The maximum SRL release in BP was observed at 3 days. The matrices produced from the ES solution with DMSO and HSA released no more than 80% SRL after 27 days in BP, even under medium exchange conditions. Therefore, PCL-based matrices containing HSA, SRL, and DMSO can be used for coating VSs with prolonged SRL delivery.

Isolation, culturing and gene expression profiling of inner mass cells from stable and vulnerable carotid atherosclerotic plaques.

The connective tissue components that form the atherosclerotic plaque body are produced by the plaque inner mass cells (PIMC), located inside the plaque. We report an approach to isolate and culture cells from the connective tissue of stable and vulnerable human atherosclerotic plaques based on elimination of non-connective tissue cells such as blood and non-plaque intima cells with a lysis buffer. The resulting plaque cells were characterized by growth capacity, morphology, transcriptome profiling and specific protein expression. Plaque cells slowly proliferated for up to three passages unaffected by the use of proliferation stimulants or changes of culture media composition. Stable plaques yielded more cells than vulnerable ones. Plaque cell cultures also contained several morphological cellular types. RNA-seq profiles of plaque cells were different from any of the cell types known to be involved in atherogenesis. The expression of the following proteins was observed in cultured plaque cells: smooth muscle cells marker α-SMA, macrophage marker CD14, extracellular matrix proteins aggrecan, fibronectin, neovascularisation markers VEGF-A, CD105, cellular adhesion receptor CD31 and progenitor/dedifferentiation receptor CD34. Differential expression of several notable transcripts in cells from stable and vulnerable plaques suggests the value of plaque cell culture studies for the search of plaque vulnerability markers.

Neutral and Negatively Charged Phosphate Modifications Altering Thermal Stability, Kinetics of Formation and Monovalent Ion Dependence of DNA G-Quadruplexes.

The effect of phosphate group modifications on formation and properties of G-quadruplexes (G4s) has not been investigated in detail. Here, we evaluated the structural, thermodynamic and kinetic properties of the parallel G-quadruplexes formed by oligodeoxynucleotides d(G4 T), d(TG4 T) and d(TG5 T), in which all phosphates were replaced with N-methanesulfonyl (mesyl) phosphoramidate or phosphoryl guanidine groups resulting in either negatively charged or neutral DNA sequences, respectively. We established that all modified sequences were able to form G-quadruplexes of parallel topology; however, the presence of modifications led to a decrease in thermal stability relative to unmodified G4s. In contrast to negatively charged G4s, assembly of neutral G4 DNA species was faster in the presence of sodium ions than potassium ions, and was independent of the salt concentration used. Formation of mixed G4s composed of both native and neutral G-rich strands has been detected using native gel electrophoresis, size-exclusion chromatography and ESI-MS. In summary, our results indicate that the phosphate modifications studied are compatible with G-quadruplex formation, which could be used for the design of biologically active compounds.

Design and Properties of Ligand-Conjugated Guanine Oligonucleotides for Recovery of Mutated G-Quadruplexes.

The formation of a guanine quadruplex DNA structure (G4) is known to repress the expression of certain cancer-related genes. Consequently, a mutated G4 sequence can affect quadruplex formation and induce cancer progression. In this study, we developed an oligonucleotide derivative consisting of a ligand-containing guanine tract that replaces the mutated G4 guanine tract at the promoter of the vascular endothelial growth factor (VEGF) gene. A ligand moiety consisting of three types of polyaromatic hydrocarbons, pyrene, anthracene, and perylene, was attached to either the 3' or 5' end of the guanine tract. Each of the ligand-conjugated guanine tracts, with the exception of anthracene derivatives, combined with other intact guanine tracts to form an intermolecular G4 on the mutated VEGF promoter. This intermolecular G4, exhibiting parallel topology and high thermal stability, enabled VEGF G4 formation to be recovered from the mutated sequence. Stability of the intramolecular G4 increased with the size of the conjugated ligand. However, suppression of intermolecular G4 replication was uniquely dependent on whether the ligand was attached to the 3' or 5' end of the guanine tract. These results indicate that binding to either the top or bottom guanine quartet affects unfolding kinetics due to polarization in DNA polymerase processivity. Our findings provide a novel strategy for recovering G4 formation in case of damage, and fine-tuning processes such as replication and transcription.

Data set on the synthesis and properties of 2',3'-dideoxyuridine triphosphate conjugated to SiO2 nanoparticles.

SiO2 nanoparticles were used as a transport system for cellular delivery of phosphorylated 2',3'-dideoxyuridine to increase its anticancer potency. This data set is related to the research article entitled "2',3'-Dideoxyuridine triphosphate conjugated to SiO2 nanoparticles: synthesis and evaluation of antiproliferative activity" (Vasilyeva et al., 2018) [1]. It includes a protocol for the synthesis of 2',3'-dideoxyuridine-5'-{N-[4-(prop-2-yn-1-yloxy)butyl]-γ-amino}-triphosphate, its identification by NMR, IR and ESI-MS, experimental procedure of covalent attachment to SiO2 nanoparticles with via Cu-catalyzed click-chemistry, experimental data on chemical stability of the conjugate at different pH values and cytotoxicity assessment of antiproliferative effect of the conjugate.

Synthesis and evaluation of aryliden- and hetarylidenfuranone derivatives of usnic acid as highly potent Tdp1 inhibitors.

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is a repair enzyme for stalled DNA-topoisomerase 1 (Top 1) cleavage complexes and other 3'-end DNA lesions. Tdp1 is a promising target for anticancer therapy, since it can repair DNA lesions caused by Top1 inhibitors leading to drug resistance. Hence, Tdp1 inhibition should result in synergistic effect with Top1 inhibitors. Twenty nine derivatives of (+)-usnic acid were tested for in vitro Tdp1 inhibitory activity using a fluorescent-based assay. Excellent activity was obtained, with derivative 6m demonstrating the lowest IC50 value of 25 nM. The established efficacy was verified using a gel-based assay, which gave close results to that of the fluorescent assay. In addition, molecular modeling in the Tdp1 substrate binding pocket suggested plausible binding modes for the active analogues. The synergistic effect of the Tdp1 inhibitors with topotecan, a Top1 poison in clinical use, was tested in two human cell lines, A-549 and HEK-293. Compounds 6k and 6x gave very promising results. In particular, 6x has a low cytotoxicity and an IC50 value of 63 nM, making it a valuable lead compound for the development of potent Tdp1 inhibitors for clinical use.

Analysis of new charge-neutral DNA/RNA analogues phosphoryl guanidine oligonucleotides (PGO) by gel electrophoresis.

Analysis and isolation of new charge-neutral phosphoryl guanidine oligonucleotides (PGO) by vertical slab electrophoresis were tested at different pH values (3-11) or in the presence of SDS as a micelle-forming agent. The most convenient way to analyze and purify phosphoryl guanidine oligonucleotides was by denaturing PAGE (8 M urea) at pH 3. The mobility of PGO is dependent on their A + C content. To analyze PGO containing only G, T or U, denaturing PAGE at pH 11 can be used, although the conditions need to be optimized. Bands were visualized by UV shadowing or Coomassie Brilliant Blue staining.

Non-covalent binding of nucleic acids with gold nanoparticles provides their stability and effective desorption in environment mimicking biological media.

The ability of gold nanoparticles to bind different substances has resulted in the high interest of researchers determining their usage as a promising carrier of various biological substances including nucleic acids (NAs) for therapeutic applications. Most publications report covalent binding (conjugation) of an NA to spherical AuNPs via the Au-S bond. In this work, we obtained non-covalent associates of different ssDNA, ssRNA and siRNAs with spherical gold nanoparticles (AuNPs) and examined their physico-chemical properties and stability in media mimicking intracellular space (bacterial 'cytosol') and cell culture media (10% FBS in DMEM). The 'cytosol' was obtained from E. coli and possessed nuclease activity. For the first time, we used the phosphoryl guanidine (dimethylimidazolidin-2-imine, Dmi) group for modification of 3'-ends to enhance the stability of ssRNAs and siRNAs against nuclease destruction. Trying to evaluate the material balance, we analyzed the whole nucleotide species obtained after incubation of NA-AuNPs associates in 'cytosol' and FBS and evaluated the degree of NAs destruction, a share of full-size NAs remained on the surface of the AuNPs and in the solution. Native ss- and siRNAs, both free and in composition of non-covalent associates with AuNPs, were less resistant to degrading factors than ssDNA. The introduction of two Dmi-groups into the ssDNA increased its stability in 'cytosol' three times within 2.5 h. Dmi-modified siRNAs in non-covalent associates with AuNPs were two times more stable than unmodified siRNA within 4 h. We showed that non-covalent siRNA-AuNPs associates serve as a kind of storage for full-size NAs and thereby prolong their presence in nuclease-active media. Our study showed that non-covalent binding of siRNAs with a surface of AuNPs provides desorption of both strands, which is necessary for siRNA functioning in living cells, and could be considered as an important way to construct siRNA and ssDNA delivery systems based on AuNPs.

2',3'-Dideoxyuridine triphosphate conjugated to SiO2 nanoparticles: Synthesis and evaluation of antiproliferative activity.

A conjugate of triphosphorylated 2',3'-dideoxyuridine (ddU) with SiO2 nanoparticles was obtained via the CuAAC click chemistry between a γ-alkynyl ddU triphosphate and azido-modified SiO2 nanoparticles. Assessment of cytotoxicity in human breast adenocarcinoma MCF7 cells demonstrated that ddU triphosphate conjugated to SiO2 nanoparticles exhibited a 50% decrease in cancer cell growth at a concentration of 183 ±â€¯57 µg/mL, which corresponds to 22 ±â€¯7 µM of the parent nucleotide, whereas the parent nucleoside, nucleotide and alkynyl triphosphate precursor do not show any cytotoxicity. The data provide an example of remarkable potential of novel conjugates of SiO2 nanoparticles with phosphorylated nucleoside analogues, even those, which have not been used previously as therapeutics, for application as new anticancer agents.