Yuri Dekhtyar

Silica Nanoparticles as the Adjuvant for the Immunisation of Mice Using Hepatitis B Core Virus-Like Particles

Advances in nanotechnology and nanomaterials have facilitated the development of silicon dioxide, or Silica, particles as a promising immunological adjuvant for the generation of novel prophylactic and therapeutic vaccines. In the present study, we have compared the adjuvanting potential of commercially available Silica nanoparticles (initial particles size of 10–20 nm) with that of aluminium hydroxide, or Alum, as well as that of complete and incomplete Freunds adjuvants for the immunisation of BALB/c mice with virus-like particles (VLPs) formed by recombinant full-length Hepatitis B virus core (HBc) protein. The induction of B-cell and T-cell responses was studied after immunisation. Silica nanoparticles were able to adsorb maximally 40% of the added HBc, whereas the adsorption capacity of Alum exceeded 90% at the same VLPs/adjuvant ratio. Both Silica and Alum formed large complexes with HBc VLPs that sedimented rapidly after formulation, as detected by dynamic light scattering, spectrophotometry, and electron microscopy. Both Silica and Alum augmented the humoral response against HBc VLPs to the high anti-HBc level in the case of intraperitoneal immunisation, whereas in subcutaneous immunisation, the Silica-adjuvanted anti-HBc level even exceeded the level adjuvanted by Alum. The adjuvanting of HBc VLPs by Silica resulted in the same typical IgG2a/IgG1 ratios as in the case of the adjuvanting by Alum. The combination of Silica with monophosphoryl lipid A (MPL) led to the same enhancement of the HBc-specific T-cell induction as in the case of the Alum and MPL combination. These findings demonstrate that Silica is not a weaker putative adjuvant than Alum for induction of B-cell and T-cell responses against recombinant HBc VLPs. This finding may have an essential impact on the development of the set of Silica-adjuvanted vaccines based on a long list of HBc-derived virus-like particles as the biological component.

Polarization of poly(vinylidene fluoride) and poly(vinylidene fluoride-trifluoroethylene) thin films revealed by emission spectroscopy with computational simulation during phase transition

The electronic structure and self-polarization of P(VDF-TrFE) Langmuir-Blodgett nanofilms were analyzed under temperature-driven phase transitions, according to their thickness, composition, and structural conformation. Both thermo-stimulated exoelectron emission (TSEE) spectroscopy and computational simulation, including quantum-chemical calculations from first principles, were carried out. PVDF and composite P(VDF-TrFE) (70:30) molecular chains as Trans and Gauche conformers, as well as crystal cells, were modeled for these TSEE analyses. The quantum-chemical calculations and the computational simulation were based on the density functional theory (DFT) as well as semi-empirical (PM3) methods. It was demonstrated that the energy of electron states, as well as the total energies of the studied P(VDF-TrFE) molecular clusters during phase transformation, is influenced by electron work function and electron affinity. Analysis was performed by combining TSEE experimental data with the computational data of t...

Electrically Charged Hydroxyapatite Enhances Immobilization and Proliferation of Osteoblasts

Hydroxyapatite (HAP) is in use to fabricate implants in dentistry and orthopaedy. To functionalise a surface of the HAP that has a direct contact to the human cells a surface electrical charge deposition is employed. The current technologies can not provide uniformity of the charge for contrarily situated surfaces.

Sensors for water safety and security

Identification and analysis of contaminants arising from occasional release or intentional discharge in unsecured water supplies are fundamental to public welfare. This calls for national and international capacities to respond, sense, detect, isolate, and mitigate threats to water quality. Using advanced nanomaterials as enabling technologies, a series of novel point and stand-off sensors and detectors for continuous and in-situ monitoring of inorganic, organic, and microbiological pollutants are described. New sensing approaches based on interaction of the semiconductor surface using electron emission and metal complexes based chiroptical switches are also described.

In Vitro Biocompatibility of Si Alloyed Multi-Principal Element Carbide Coatings.

In the current study, we have examined the possibility to improve the biocompatibility of the (TiZrNbTaHf)C through replacement of either Ti or Ta by Si. The coatings were deposited on Si and 316L stainless steel substrates by magnetron sputtering in an Ar+CH4 mixed atmosphere and were examined for elemental composition, chemical bonds, surface topography, surface electrical charge and biocompatible characteristics. The net surface charge was evaluated at nano and macroscopic scale by measuring the electrical potential and work function, respectively. The biocompatible tests comprised determination of cell viability and cell attachment to the coated surface. The deposited coatings had C/(metal+Si) ratios close to unity, while a mixture of metallic carbide, free-carbon and oxidized species formed on the film surface. The coatings’ surfaces were smooth and no influence of surface roughness on electrical charge or biocompatibility was found. The biocompatible characteristics correlated well with the electrical potential/work function, suggesting a significant role of surface charge in improving biocompatibility, particularly cell attachment to coatings surface. Replacement of either Ti or Ta by Si in the (TiZrNbTaHf)C coating led to an enhanced surface electrical charge, as well as to superior biocompatible properties, with best results for the (TiZrNbSiHf)C coating.

Towards Optically Induced Semiconductor Human Exhalation Gas Sensor

It is known that there is a number of VOC (volatile organic compounds) in exhaled human breath that can be used as biomarkers [1, 2]. To reach screening of the patients the exhalation gas sensor should be light, cheap and sensitive. Semiconductor gas sensors can offer advantages in size, but they are characterized with a long response time, short lifespan, lack of selectivity [3, 4, 5].

Emission local testing of mechanical stresses in surface layer of silicon

Mechanical stresses change energy gap in semiconductors. Thus, a photoelectric work function is dependent on this effect. In such a view surface layers elastic deformations are recorded by measuring of photoelectron emission quantum yield.

Optically Induced Semiconductor Gas Sensor: Acetone Detection Range using Continuous and Cyclic Optical Irradiation Types

In previous studies the possibility to use optically induced semiconductors to sense acetone vapors was demonstrated [1]. One of the studies demonstrated the possibility to sense and determine various solvent gases, where acetone vapor showed the highest signal increase [2]. In this study, two optical irradiation types (continuous and cyclical) are compared.

Wettability of the PMMA surface caused by its polarization due to UV radiation

Wettability of the poly methyl methacrylate (PMMA) surface defines its biocompatibility being essential factor for biomedical applications. The processed surface degrades in time therefore the prostheses/lens should be repaired to keep the patient at a high life quality level. However the most common methods can be considered as sophisticated (plasma treatment, laser treatment, etc.). The research presents novel result on the PMMA surface wettability engineering by means of non-ionizing ultraviolet radiation (200-400nm). Results (electron work function (φ), photoelectron emission spectra, optical absorption) show alteration from hydrophobic to hydrophilic surface behaviour. Both the surface (photoelectron emission) and the bulk (optical absorption) interacting centres were influenced by radiation showing maximum effect after 45 minutes of irradiation.

Strength and Electron Features of Irradiated Bone

AbstractRadiation applied for therapy and diagnostics damages molecular/atomic couples of biotissues, bones being among them. As a result, electron peculiarities and mechanical behavior of the latter are altered. Correlation between strength of the irradiated bone and its electron features explored due to photo- and exoelectron emission measurements is reviewed.