Irina V. Sukhorukova

Boron Nitride Nanoparticles with a Petal-Like Surface as Anticancer Drug-Delivery Systems

Nanoparticles (NPs) have a great potential as nanosized drug-delivery carriers. Such systems must safely deliver the drug to the site of the tumor without drug leakage, effectively penetrate inside cancer cells, and provide intracellular drug release. Herein we developed an original and simple method aimed at the fabrication of spherical boron nitride NPs (BNNPs), 100-200 nm in diameter, with peculiar petal-like surfaces via chemical vapor deposition. Such structures were found to be able to absorb a large amount of antitumor drug-killing tumor cells. They revealed low cytotoxicity and rapid cellular uptake. BNNPs were saturated with doxorubicin (DOX) and then dispersed. The BNNPs loaded with DOX (BNNPs-DOX) were stable at neutral pH but effectively released DOX at pH 4.5-5.5. MTT assay and cell growth testing showed that the BNNPs-DOX nanocarriers had been toxic for IAR-6-1 cells. BNNPs loaded with DOX penetrated into the neoplastic IAR-6-1 cells using endocytic pathways, and then DOX released into the cytoplasm and cell nuclei and resulted in cell death.

Characteristics and in vitro response of thin hydroxyapatite–titania films produced by plasma electrolytic oxidation of Ti alloys in electrolytes with particle additions

Enhanced incorporation of hydroxyapatite nanoparticles in porous titania coating formed by plasma electrolytic oxidation significantly increases surface osteogenic activity.

Approaches for Controlled Ag+ Ion Release: Influence of Surface Topography, Roughness, and Bactericide Content

Silver is the most famous bactericidal element known from ancient times. Its antibacterial and antifungal effects are typically associated with the Ag ionization and concentration of Ag+ ions in a bacterial culture. Herein we thoroughly studied the influence of surface topography and roughness on the rate of Ag+ ion release. We considered two types of biocompatible and bioactive TiCaPCON-Ag films with 1 and 2 at. % of Ag and nine types of Ti surfaces with an average roughness varying in the range from 5.4 × 10-2 to 12.6 μm and different topographic features obtained through polishing, sandblasting, laser treatment, and pulsed electrospark deposition. It is demonstrated that the Ag+ ion release rates do not depend on the Ag content in the films as the main parameter, and it is other factors, such as the state of Ag agglomeration, surface topography and roughness, as well as kinetics of surface oxidation, that play a critical role. The obtained results clearly show a synergistic effect of the Ag content in the film and surface topography and roughness on Ag+ ion release. By changing the surface topographical features at a constant content of bactericidal element, we showed that the Ag+ ion release can be either accelerated by 2.5 times or almost completely suppressed. Despite low Ag+ ion concentration in physiological solution (<40 ppb), samples with specially fabricated surface reliefs (flakes or holes) showed a pronounced antibacterial effect already after 3 h of immersion in E. coli bacterial culture. Thus, our results open up new possibilities for the production of cost-effective, scalable, and biologically safe implants with pronounced antibacterial characteristics for future applications in the orthopedic field.

The defining role of pH in the green synthesis of plasmonic gold nanoparticles using Citrus limon extract

The effect of pH on the growth pathways and final morphology of the plasmonic gold nanoparticles (AuNPs) synthesized using natural Citrus limon extract was in the spotlight. In acidic medium (pH 2.5–5), the growth of AuNPs is fast and involves an intermediate aggregation stage, whereas pH 7–9 results in much slower nucleation-growth route. The synthesis at pH 5 was shown to be the most appropriate for preparation of 8-nm gold nanospheres with narrow size distribution and amazingly bright surface plasmon resonance. The reported findings contribute to better understanding of the processes in “green” AuNP synthesis using C. limon extract and can promote its implementation in sustainable industry. Pronounced plasmonic properties and eco-friendly precursors of the AuNPs make them an essential material for biological tagging and cell visualization.

Effect of BN Nanoparticles Loaded with Doxorubicin on Tumor Cells with Multiple Drug Resistance

Herein we study the effect of doxorubicin-loaded BN nanoparticles (DOX-BNNPs) on cell lines that differ in the multidrug resistance (MDR), namely KB-3-1 and MDR KB-8-5 cervical carcinoma lines, and K562 and MDR i-S9 leukemia lines. We aim at revealing the possible differences in the cytotoxic effect of free DOX and DOX-BNNP nanoconjugates on these types of cells. The spectrophotometric measurements have demonstrated that the maximum amount of DOX in the DOX-BNNPs is obtained after saturation in alkaline solution (pH 8.4), indicating the high efficiency of BNNPs saturation with DOX. DOX release from DOX-BNNPs is a pH-dependent and DOX is more effectively released in acid medium (pH 4.0-5.0). Confocal laser scanning microscopy has shown that the DOX-BNNPs are internalized by neoplastic cells using endocytic pathway and distributed in cell cytoplasm near the nucleus. The cytotoxic studies have demonstrated a higher sensitivity of the leukemia lines to DOX-BNNPs compared with the carcinoma lines: IC50(DOX-BNNPs) is 1.13, 4.68, 0.025, and 0.14 μg/mL for the KB-3-1, MDR KB-8-5, K562, and MDR i-S9 cell lines, respectively. To uncover the mechanism of cytotoxic effect of nanocarriers on MDR cells, DOX distribution in both the nucleus and cytoplasm has been studied. The results indicate that the DOX-BNNP nanoconjugates significantly change the dynamics of DOX accumulation in the nuclei of both KB-3-1 and KB-8-5 cells. Unlike free DOX, the utilization of DOX-BNNPs nanoconjugates allows for maintaining a high and stable level of DOX in the nucleus of MDR KB-8-5 cells.

Fabrication method, structure, mechanical, and biological properties of decellularized extracellular matrix for replacement of wide bone tissue defects.

The present paper was focused on the development of a new method of decellularized extracellular matrix (DECM) fabrication via a chemical treatment of a native bone tissue. Particular attention was paid to the influence of chemical treatment on the mechanical properties of native bones, sterility, and biological performance in vivo using the syngeneic heterotopic and orthotopic implantation models. The obtained data indicated that after a chemical decellularization treatment in 4% aqueous sodium chlorite, no noticeable signs of the erosion of compact cortical bone surface or destruction of trabeculae of spongy bone in spinal channel were observed. The histological studies showed that the chemical treatment resulted in the decellularization of both bone and cartilage tissues. The DECM samples demonstrated no signs of chemical and biological degradation in vivo. Thorough structural characterization revealed that after decellularization, the mineral frame retained its integrity with the organic phase; however clotting and destruction of organic molecules and fibers were observed. FTIR studies revealed several structural changes associated with the destruction of organic molecules, although all organic components typical of intact bone were preserved. The decellularization-induced structural changes in the collagen constituent resulted changed the deformation under compression mechanism: from the major fracture by crack propagation throughout the sample to the predominantly brittle fracture. Although the mechanical properties of radius bones subjected to decellularization were observed to degrade, the mechanical properties of ulna bones in compression and humerus bones in bending remained unchanged. The compressive strength of both the intact and decellularized ulna bones was 125-130 MPa and the flexural strength of humerus bones was 156 and 145 MPa for the intact and decellularized samples, respectively. These results open new avenues for the use of DECM samples as the replacement of wide bone tissue defects.

Correction: Inkjet printing of silver rainbow colloids for SERS chips with polychromatic sensitivity

Correction for ‘Inkjet printing of silver rainbow colloids for SERS chips with polychromatic sensitivity’ by K. E. Yorov et al., RSC Adv., 2016, 6, 15535–15540.

A comparative study of the structure and chemical properties of nanocomposite TiCaPCON-Ag coatings

To induce antibacterial activity in bioactive TiCaPCON coatings, materials have been doped with Ag in a quantity of 0.4–4.0 at %. Silver has been introduced into the coatings via two methods. Coatings with 0.4, 1.2, and 4.0 at % Ag content have been fabricated via simultaneous sputtering of a compositional TiC0.5-Ca3(PO4)2 target, which was obtained via self-propagating high temperature synthesis, and of a metallic Ag target. TiCaPCON-Ag (4.0 at %) coating was also fabricated via ion Ag implantation of preliminarily obtained TiCaPCON. The content and element distribution over the thickness of the coating were studied via glow discharge optical emission spectroscopy (GD-OES). The structure and morphology of the coatings have been probed via scanning electron microscopy. The results showed the formation of Ag particles in both the bulk and on the surface of the coatings, but their size and distribution over the coating thickness are found to depend on both the Ag concentration and method of sputtering of coatings. The effect of substrate temperature on Ag particle distribution in the coating is established. The study of kinetics of Ag dissolution via inductively coupled plasma mass-spectrometry and electrochemical methods has revealed that Ag dissolution rate is defined by the ratio of Ag nanoparticle size to the thickness of an oxide layer on the surface.

Inkjet printing of silver rainbow colloids for SERS chips with polychromatic sensitivity

Pristine and artificially mixed silver colloids of diverse anisotropic silver nanoparticles were used as “rainbow” colloidal silver inks for inkjet printing of cellulose-based active elements with polychromatic sensitivity for surface-enhanced Raman spectroscopy optical sensors. Platelet silver nanocrystallites possessing different plasmonic bands in the visual spectral range were grown in water–polyol liquors of different viscosities to prevent nanoparticle agglomeration and provide colloidal stability for at least one year. SERS tests of model photostable dyes revealed bright enhanced signals under several standard wavelengths of laser irradiations thus demonstrating better practical applications of such substrates.

Multifunctional bioactive nanostructured films

Multifunctional bioactive nanostructured films (MuBiNaFs), with an excellent combination of chemical, mechanical, tribological, and biological properties, were developed and deposited by sputtering of composite targets produced via the self-propagating high-temperature synthesis method. Reviewed substrate materials included Ti-, Ni-, and Co-based alloys, bio-insoluble polymers, and decellularized donor’s bones. The films were characterized in terms of their mechanical and tribological properties, biocompatibility, bioactivity, and bactericidal activity. The results showed that the MuBiNaF deposition can be effectively combined with either a bulk material modification to improve its mechanical properties, or a surface modification to control surface roughness and blind porosity. Among other promising applications, the fabrication of hybrid materials with the capability of controlled release of antimicrobial agent is mentioned.