Search

Composite bioceramic and hydrogel-based containers harboring alkaline phosphatase are generated through encapsulation of this enzyme by its immobilization into CaCO3-based bioceramic materials in c...

The photocatalytic degradation of organic molecules is one of the effective ways for water purification. At this point, photocatalytic microreactor systems seem to be promising to enhance the versatility of the photoassisted degradation approach. Herein, we propose photoresponsive microcapsules prepared via layer-by-layer assembly of polyelectrolytes on the novel CaCO3/TiO2 composite template cores. The preparation of CaCO3/TiO2 composite particles is challenging because of the poor compatibility of TiO2 and CaCO3 in an aqueous medium. To prepare stable CaCO3/TiO2 composites, TiO2 nanoparticles were loaded into mesoporous CaCO3 microparticles with a freezing-induced loading technique. The inclusion of TiO2 nanoparticles into CaCO3 templates was evaluated with scanning electron microscopy and elemental analysis with respect to their type, concentration, and number of loading iterations. Upon polyelectrolyte shell assembly, the CaCO3 matrix was dissolved, resulting in microreactor capsules loaded with TiO2 nanoparticles. The photoresponsive properties of the resulted capsules were tested by photoinduced degradation of the low-molecule dye rhodamine B in aqueous solution and fluorescently labeled polymer molecules absorbed on the capsule surface under UV light. The exposure of the capsules to UV light resulted in a pronounced degradation of rhodamine B in capsule microvolume and fluorescent molecules on the capsule surface. Finally, the versatility of preparation of multifunctional photocatalytic and magnetically responsive capsules was demonstrated by iterative freezing-induced loading of TiO2 and magnetite Fe3O4 nanoparticles into CaCO3 templates.

Development of novel drug delivery systems providing the enhanced accumulation of the therapeutic agents in the area of pathology reducing in the meantime the systemic toxic effects is of great research interest. Here we introduce the study on the antifungal drug “Naftifine” immobilization into the particulate delivery system based on vaterite submicron particles. Two different techniques are proposed for the antimycotic incorporation: adsorption onto the surface of freshly-prepared vaterite particles from the drug solution and co-precipitation of the drug molecules during the particle synthesis. Various optical methods were used to investigate the immobilization process. Thus, laser Raman spectroscopy was used to confirm the successful carrier loading with naftifin hydrochloride. A spectrofluorimetric method was applied for the quantitative determination of the drug loading efficiency into vaterite matrix. The study revealed that the co-precipitation technique allows the immobilization of the highest antimycotic percentage (9 wt %). Scanning electron microscopy was used to monitor the stability of the naftifin-loaded carriers under their incubation in deionized water, saline and cell culture medium. The slowdown of vaterite recrystallization process was observed for the protein-containing medium. Such effect holds out the prospect of drug release prolongation for the future application of the proposed carries in living systems.

Flexible electronics attract great interest due to their wide opportunities for practical application in the field of wireless communication, personalized medicine, security, etc. Flexible wireless technologies require low profile, lightweight, and compact antennas. In this work, an antenna on a flexible dielectric substrate for the ISM range and 2G/3G/4G standards of cellular bands was designed and numerically studied. Also, we plan to fabricate the designed antenna with the help of our original technological approach based on the magnetron sputtering and nanosecond laser ablation. Several preliminary results of microfabrication opportunities with the help of the mentioned above approach are shown.

In recent decades, there has been a steady trend towards the miniaturization of electronic devices, and their key components. Fabrication of such microsized devices and their key part is a real challenge. One of the well-known methods of microfabrication is laser ablation based micromachining. In this work, we study the peculiarities of the influence of nanosecond laser pulses on thin copper films on dielectric substrates. The main aim of this work is to reveal the effective regime of nanosecond ablation of the copper thin film with different thicknesses. The deposition of a copper thin film on the dielectric substrate was carried out by magnetron sputtering. Glass slides were used as dielectric substrates. To quantitatively describe the interaction of a thin copper film with laser pulses of nanoseconds duration, the fluence was calculated taking into account the velocity of the laser spot. The threshold of fluence that needs to effectively ablate the rectangular region of the copper film with a certain thickness was revealed. The obtained results will be used in the future in precision microfabrication of planar electromagnetic structures for vacuum electron devices operating in millimeter-wave bands.

Millimeter-band traveling-wave tubes with multiple electron beams have attracted an increasing interest thanks to higher output power. In this work, we report the results of the development of the technological approach to microfabrication of a meander-line slow-wave structure for millimeter-band traveling-wave tubes with multiple sheet electron beams. We used a precision CNC laser machine equipped with a 1064-nm pulsed YAG:Nd fiber laser maintaining regimes with the duration of laser pulses from 200 ns to 8 ns. Several SWS samples have been fabricated and studied by scanning electron and optical microscopy methods

Mineralization of hydrogel biomaterials with calcium phosphate (CaP) is considered advantageous for bone regeneration. Mineralization can be both induced by the enzyme alkaline phosphatase (ALP) and promoted by calcium-binding biomolecules, such as plant-derived polyphenols. In this study, ALP-loaded gellan gum (GG) hydrogels were enriched with gallotannins, a subclass of polyphenols. Five preparations were compared, namely three tannic acids of differing molecular weight (MW), pentagalloyl glucose (PGG), and a gallotannin-rich extract from mango kernel (Mangifera indica L.). Certain gallotannin preparations promoted mineralization to a greater degree than others. The various gallotannin preparations bound differently to ALP and influenced the size of aggregates of ALP, which may be related to ability to promote mineralization. Human osteoblast-like Saos-2 cells grew in eluate from mineralized hydrogels. Gallotannin incorporation impeded cell growth on hydrogels and did not impart antibacterial activity. In conclusion, gallotannin incorporation aided mineralization but reduced cytocompatibility.

We demonstrate a novel approach to the controlled loading of inorganic nanoparticles and proteins into submicron- and micron-sized porous particles. The approach is based on freezing/thawing cycles, which lead to high loading densities. The process was tested for the inclusion of Au, magnetite nanoparticles, and bovine serum albumin in biocompatible vaterite carriers of micron and submicron sizes. The amounts of loaded nanoparticles or substances were adjusted by the number of freezing/thawing cycles. Our method afforded at least a three times higher loading of magnetite nanoparticles and a four times higher loading of protein for micron vaterite particles, in comparison with conventional methods such as adsorption and coprecipitation. The capsules loaded with magnetite nanoparticles by the freezing-induced loading method moved faster in a magnetic field gradient than did the capsules loaded by adsorption or coprecipitation. Our approach allows the preparation of multicomponent nanocomposite materials with designed properties such as remote control (e.g. via the application of an electromagnetic or acoustic field) and cargo unloading. Such materials could be used as multimodal contrast agents, drug delivery systems, and sensors.

The enhancement of the Raman light scattering signal from the surface of the porous hybrid biocomposites based on polyhydroxybutyrate (PHB), calcium carbonate (CaCO3), and nanoplasmonic Ag particles is investigated. Based on PHB, fibrous scaffolds are obtained by the electrospinning technique. The fibrous scaffolds have been covered by CaCO3 and Ag nanoparticles by means of mineralization in salt solutions and Ag reduction reaction. Successful formation of the CaCO3 and Ag nanoparticles on the scaffold surface has been confirmed by the data of scanning electron microscopy, x-ray diffraction analysis, and infrared spectroscopy. Surface-enhanced Raman spectroscopy (SERS) of the obtained sample surface has demonstrated a significant enhancement of the Rhodamine 6G signal (Ef > 105) in comparison with the reference sample where the analyte concentration and the laser power were 100 times higher. Thus, the present research has confirmed prospects for the application of biocomposites based on polyhydroxybutyrate for detection and investigation of biomolecules by the SERS method.

Designing advanced biomaterials for tissue regeneration with drug delivery and release functionalities remains a challenge in regenerative medicine. In this research, we have developed novel composite scaffolds based on polymeric polycaprolactone fibers coated with porous calcium carbonate structures (PCL/CaCO3) for tissue engineering and have shown their drug delivery and release in rats. In vivo biocompatibility tests of PCL/CaCO3 scaffolds were complemented with in vivo drug release study, where tannic acid (TA) was used as a model drug. Release of TA from the scaffolds was realized by recrystallization of the porous vaterite phase of calcium carbonate into the crystalline calcite. Cell colonization and tissue vascularization as well as transplantability of developed PCL/CaCO3 + TA scaffolds were observed. Detailed study of scaffold transformations during 21-day implantation period was followed by scanning electron microscopy and X-ray diffraction studies before and after in vivo implantation. The presented results demonstrate that PCL/CaCO3 scaffolds are attractive candidates for implants in bone regeneration and tissue engineering with a possibility of loading biologically active molecules and controlled release.

Polystyrene thin films were modified by the radio frequency argon plasma treatment. Effect of plasma processing on surface morphology was investigated by scanning electron microscopy and an atomic force microscopy. Volume structure of polystyrene films has been revealed after surface treatment by radio frequency argon plasma and was represented polymer coils organized in chains 1.8 μm in length and 0.21 μm in width. Dependence of surface roughness and wettability on plasma exposure time was investigated. It was shown that varying of treatment time in the small range leads to considerable changing of the surface roughness parameter and to formation of nano-sized pores.

Efficient delivery of genetic material to primary cells remains challenging. Here, efficient transfer of genetic material is presented using synthetic biodegradable nanocarriers, resembling extracellular vesicles in their biomechanical properties. This is based on two main technological achievements: generation of soft biodegradable polyelectrolyte capsules in nanosize and efficient application of the nanocapsules for co-transfer of different RNAs to tumor cell lines and primary cells, including hematopoietic progenitor cells and primary T cells. Near to 100% efficiency is reached using only 2.5 × 10−4 pmol of siRNA, and 1 × 10−3 nmol of mRNA per cell, which is several magnitude orders below the amounts reported for any of methods published so far. The data show that biodegradable nanocapsules represent a universal and highly efficient biomimetic platform for the transfer of genetic material with the utmost potential to revolutionize gene transfer technology in vitro and in vivo.

Microstructured optical waveguides (MOW) are of great interest for chemical and biological sensing. Due to the high overlap between a guiding light mode and an analyte filling of one or several fiber capillaries, such systems are able to provide strong sensitivity with respect to variations in the refractive index and the thickness of filling materials. Here, we introduce a novel type of functionalized MOWs whose capillaries are coated by a layer-by-layer (LBL) approach, enabling the alternate deposition of silica particles (SiO2) at different diameters&mdash, 300 nm, 420 nm, and 900 nm&mdash, and layers of poly(diallyldimethylammonium chloride) (PDDA). We demonstrate up to three covering bilayers consisting of 300-nm silica particles. Modifications in the MOW transmission spectrum induced by coating are measured and analyzed. The proposed technique of MOW functionalization allows one to reach novel sensing capabilities, including an increase in the effective sensing area and the provision of a convenient scaffold for the attachment of long molecules such as proteins.

At present day, silver nanoparticles are widely used in different fields of human activity. Due to the unique combination of physical and chemical properties, silver nanoparticles have high reactivity and antibacterial activity against microorganisms. For the same reason, silver nanoparticles can render a cytotoxic effect on eukaryotic cells. The usage of different polymeric compounds as stabilizers can allow reducing of it and saving antibacterial activity. With this regard, the examination of new nanoparticles' stabilizers is a vital task. In addition, for the safe usage of silver nanoparticles it is necessary to estimate some of their physical properties and cytotoxicity. Here we evaluated the shape, size, UV-visible absorption, fluorescence, z-potential and cytotoxicity of single silver nanoparticles and nanoparticles, stabilized by polyvinyl alcohol, sodium carboxymethylcellulose, sodium dodecyl sulfate, sodium oleate and agarose. We found that nanoparticles stabilized by all investigated polymeric compounds with the exception of sodium dodecyl sulfate and sodium oleate did not possess significant cytotoxic effect on the test cell culture.

Development of a skin-targeted particulate delivery system providing an extended or sustained release of the payload and a localized therapeutic effect is one of the main challenges in the treatment of fungal skin infections. In the topical administration of antifungals, the drug should penetrate into the stratum corneum and lower layers of the skin in effective concentrations. Here, we introduce biodegradable calcium carbonate carriers containing 4.9% (w/w) of naftifine hydrochloride antimycotic allowing the efficient accumulation into the skin appendages. The proposed particulate formulation ensures the enhancement of the local drug concentration, prolongation of the payload release, and control over its rate. Furthermore, it provides a highly efficient cellular uptake and excellent bioavailability in vitro and enables a deep penetration during transfollicular delivery in vivo. The enhanced fungi growth inhibition efficiency of naftifine-loaded calcium carbonate carriers compared to naftifine solution makes them a promising alternative to creams and gels currently existing on the market.

Carbon dots (CDs) are usually used as an alternative to other fluorescent nanoparticles. Apart from fluorescence, CDs also have other important properties for use in composite materials, first of all their ability to absorb light energy and convert it into heat. In our work, for the first time, CDs have been proposed as an alternative to gold nanostructures for harvesting light energy, which results in the opening of polymer-based containers with biologically active compounds. In this paper, we propose a method for the synthesis of polylactic acid microchamber arrays with embedded CDs. A comparative analysis was made of the damage to microchambers functionalized with gold nanorods and with CD aggregates, depending on the wavelength and power of the laser used. The release of fluorescent cargo from the microchamber arrays with CD aggregates under laser exposure was demonstrated.

A novel type of microcontainers based on hollow silver alginate microspheres and magnetite nanoparticles is reported as development of recently published technology. Magnetite nanoparticles were incorporated by two methods - co-precipitation with porous calcium carbonate during template formation and adsorption onto CaCO3 particles or microcontainers' shell. Amount of magnetite loaded and microshells size (4.6 to 6.9 μm) were found to depend on the chosen method for magnetite nanoparticles incorporation. Stability of hollow microshells in saline, phosphate buffer and culturing media was studied. Microcontainers' susceptibility to magnetic field was investigated in solutions of varied viscosity, and their group movement velocity under constant magnetic field was evaluated by sequential optical microscopy imaging. Cell viability tests with prepared microshells were performed that demonstrated negligible cytotoxicity effect on human dermal fibroblasts cells. With HeLa cells moderate viability inhibition was found at high carriers:cells ratio at early time points which is attributed to more active and receptor-mediated endocytosis of carriers as well as known cytotoxicity of magnetite in some cancer cells. At 24 and 48 h time points HeLa cells proliferation fully recovers. Reported data opens perspectives for further biomedical-oriented studies and application of this novel kind of microcontainers with a number of techniques applicable for imaging, control and triggered cargo release provided by presence of silver and magnetite nanoparticles in the carriers and their suitability for further versatile functionalization by traditional LbL approach if needed.

A sensor based on microstructured waveguides (MWGs) with a hollow core inner surface covered with polyelectrolyte-layer-stabilized gold nanostars was developed for the SERS sensing of dissolved analytes. A polyelectrolyte-layer coating over the inner surface of glass cladding served as a spacer, reducing nonlinear optical effects in the glass near plasmonic hotspots of nanoparticles, as a stabilizing agent for thermodynamically unstable gold nanostars and as an optical coating for the fine-tuning of MWG bandgaps. This approach can be used to construct different kinds of SERS sensors for dissolved analytes, providing conservation, the prevention of coagulation, and the drying of a liquid sample for the time required to record the signal.

The treatment with high frequency currents (HFC) is traditionally used to improve the mechanical properties of metal products, in particular hardness and wear resistance. A new method of carburization of titanium samples in a solid carburizer using HFC is proposed in the work. The temperature of the carburization is characterized by a wide range from 1000 to 1400 °C. As a result of thermochemical treatment, a hard coating of TiC (H ≥ 20 GPa) with a microstructure (d = 7-14 μm) consisting of nanoparticles (d = 10-12 nm) is formed on the titanium surface. These coatings are widely used in friction pairs for various purposes, including machinery, instrumentation and medicine.

Multifunctional silver alginate hydrogel microspheres are assembled via a template assisted approach using calcium carbonate cores. Sodium alginate is immobilized into the highly porous structure of calcium carbonate microspheres followed by cross-linking in the presence of silver ions. The simultaneous processes of the growth of silver nanoparticles in the alginate matrix and the removal of the calcium carbonate template are triggered by ascorbic acid. The abundance of silver nanoparticles and their interparticular junctions in the alginate network allow for the detection of solutes using Raman spectroscopy using the surface of the plasmonic microspheres. Rhodamine B was used to illustrate the potential applications of such multifunctional plasmonic alginate hydrogel microspheres for sensing at low concentrations. A proof of principle for using such particles for the quick identification of microorganisms is then demonstrated using the Escherichia coli bacterium.

SERS enabling substrates with increased sensitivity, their manufacturing reproducibility and enhanced structural stability are highly demanded in SERS applications. Therefore our main aim was to elaborate a simple and inexpensive method of functionalization of electrospun chitosan nanofibers by using silver nanoparticles (AgNP). For that purpose we established a protocol where we were able to control the density of AgNP on the surfaces of nanofibers, and thus electromagnetic hotspots, simply by variation of Tollens' reagent. By webbing of such fibers we were able to prepare films that were enabling SERS either of solutes or macromolecular structures such as bacterial cells. Especially, to detect bacterial cells we established two approaches of immobilisation of cells within the films, which enabled their detection with enhancement of sensitivity by a factor of 105 and an average of 25% spot-to-spot variation.

We have designed multifunctional silver alginate hydrogel microcontainers referred to as loaded microcapsules with different sizes by assembling them via a template assisted approach using natural, highly porous calcium carbonate cores. Sodium alginate was immobilized into the pores of calcium carbonate particles of different sizes followed by cross-linking via addition of silver ions, which had a dual purpose: on one hand, the were used as a cross-linking agent, albeit in the monovalent form, while on the other hand they have led to formation of silver nanoparticles. Monovalent silver ions, an unusual cross-linking agent, improve the sensitivity to ultrasound, lead to homogeneous distribution of silver nanoparticles. Silver nanoparticles appeared on the shell of the alginate microcapsules in the twin-structure as determined by transmission electron microscopy. Remote release of a payload from alginate containers by ultrasound was found to strongly depend on the particle size. The possibility to use such particles as a platform for label-free molecule detection based on the surface enhanced Raman scattering was demonstrated. Cytotoxicity and cell uptake studies conducted in this work have revealed that microcontainers exhibit nonessential level of toxicity with an efficient uptake of cells. The above-described functionalities constitute building blocks of a theranostic system, where detection and remote release can be achieved with the same carrier.

This article is dedicated to synthesis of aqueous solutions of nanoparticles based on rosin. Dependence of colloidal stability of rosin nanoparticles (RNP) on different factors (such as pH, solvent nature, and temperature) were investigated and discussed. Obtained RNP samples were characterized by dynamic light scattering, UV-visible absorbance spectroscopy, and scanning electron microscopy. It was found that RNP usually have size in the range 100‒200 nm with a maximal stability at neutral pH which is caused by relatively high surface charge of RNP (‒40 mV). Acidic media leads to fast precipitation of RNP, while alkali one leads to complete dissolution of the RNP due to formation of abietates (abietic acid is the main component of rosin).

We have studied the hardness and elastic modulus of rutile (TiO2) oxide coatings formed on the surface of commercial grade VT1-00 titanium treated by high-frequency current (HFC). The mechanism of formation of superhard oxide coatings with thicknesses within 2–3 μm and submicron-grained structure consisting of prismatic crystallites with dimensions of 200–400 nm. It is established that, at high temperatures (within 1000–1200°C) and short HFC treatment durations (30–300 s), the oxide coatings are characterized by hardnesses of about 61–78 GPa and elastic moduli within 330–680 GPa.

Research results on the chemical composition and surface morphological characteristics of zirconium products after machining and treatment with high-frequency currents are described. It was established that at the temperature range from 600 to 1200 °C and duration of heat treatment from 30 to 300 seconds oxide coatings consisting of nano-grains are formed.

Polyelectrolyte microcapsules functionalized by Fe3O4 nanoparticles have proved to be perspective magnetic resonance (MR) contrast agents. Here we report about submicron-sized capsules with a shell made of poly-L-arginine and dextran sulfate. Such polymers are biodegradable, thus they are suitable to use as components of drug delivery carriers. To functionalize submicrocapsules by magnetite freezing and layer-by-layer method were used. MR study of obtained samples was carried out, and signal intensity change dependencies on submicrocapsules concentration by mass amount of iron oxide (III) nanoparticles were shown. The sample with optimal MR contrast characteristics was found as well, and an ability to use it as a bimodal MR agent was demonstrated.

Prospective composite bioceramic titania coatings were obtained on intraosseous implants fabricated from cp-titanium and medical titanium alloy VT16 (Ti-2.5Al-5Mo-5V). Consistency changes of morphological characteristics, mechanical properties and biocompatibility of experimental titanium implant coatings obtained by oxidation during induction heat treatment are defined. Technological recommendations for obtaining bioceramic coatings with extremely high strength on titanium items surface are given.

Prospective composite bioceramic titania coatings were obtained on intraosseous implants fabricated from medical titanium alloy VT16 (Ti-2.5Al-5Mo-5V). Consistency changes of morphological characteristics, physico-mechanical properties and biocompatibility of experimental titanium implant coatings obtained by oxidation during induction heat treatment are defined. Technological recommendations for obtaining bioceramic coatings with extremely high strength on titanium items surface are given.

The characteristic sizes of elementary crystallites in the composition of dentine substrate with calciumphosphate crystal formations on its surface have been studied using x-ray diffraction (XRD) analysis for phase identification. Most probable mechanisms explaining changes in elementary crystallite sizes in the process of crystal formation were discussed.

Crystal formations were observed on the surface of etched dentine after it had been exposed to 95% ethanol in solution for 30 days at room temperature. 3D visualization of surface formations was carried out using a scanning electron microscope and Alicona 3D MeX software (Alicona GmbH). Metric characteristics of the mentioned above structures were evaluated and the nature of possible errors on the steps of model design was studied. It was shown that the shape of crystal models were likely to be approximated by ellipsoid segments.

In the present study a new adhesive system with embedded PVP-stabilized nano-particulate silver markers has been designed. Nanosized silver was used as a radio-opaque contrast material in SEM examination of adhesive system in dentine. It was studied the impact of nano-particulate silver fillers on rheological properties of adhesive system and its penetration in dentine volume. A SEM comparative evaluation of resin replicas produced using adhesive system with embedded silver nanoparticles and that without ones was carried out. It was shown that embedding of silver nanoparticles into adhesive system did not make its penetration worse. It was established that embedding of nanosized silver changed adhesive system morphology. The methodology that allows visualizing interfaces and intermediate layers between dentine, adhesive system and restorative material using silver nano-particulate markers was developed and approved. Silver nanoparticles were used to compare the objective depth of penetration of adhesive systems of different generations in root dentine with differently oriented dentinal tubules, bonding resin delivery and gravity.

Laboratory experiments conducted in Saratov State University in the first half of 2012 revealed crystal formations on the surface of etched dentine after it had been exposed to 95% ethanol in solution for 30 days at room temperature. It was discovered that the structures observed were calcium-phosphate crystals. The nature of crystal formation on rough dentine surface was described based on substance diffusion in solution, which resulted in dentine becoming spatially inhomogeneous over time. The crystal formation was established to be determined by the limited ion redistribution in dentine material.

In photodynamic therapy (PDT), photosensitizers are required to arrive in high concentrations at selective targets like cancer cells avoiding toxicity in healthy tissue. In this work, we propose the application of porous calcium carbonate carriers in the form of polycrystalline vaterite for this task. We investigated the loading efficiency for the photosensitizer Photosens in vaterite micro- and nanocarriers. A possible release mechanism depending on the surrounding pH was studied, showing a fast degradation of the carriers in buffers below pH 7. These results hold out the prospect of a novel PDT drug delivery system. Variation of particle size or additional coatings allow custom-design of workload release curves. An intrinsic cancer-sensitivity can be expected from the pH-dependent release in the acidic microenvironment of cancer tissue.