Развитие научных основ новых методов интенсификации процессов тепломассообмена в рабочих средах воздействием силовых полей периодической интенсивности

Проведено оглядовий аналіз результатів досліджень, виконаних у відділі високотемпературної теплотехніки ІГТМ НАНУ з впливу вібраційних полів на тепломассоперенос в рідких робочих середовищах у великому об'ємі, каналах і пористих структурах.Results of research performed in the department of high-temperature heat engineering of IGTM NAS of Ukraine on the effect of vibration on the heat and mass transfer in liquid working media, in a large volume in channels and in porous structures are reviewed

Mineralization and bone regeneration using a bioactive elastin-like recombinamer membrane

Producción CientíficaIn the field of tissue engineering, the properties of the scaffolds are of crucial importance for the success of the application. Hybrid materials combine properties of the different components that constitute them. In this study hybrid gels of elastin-like recombinamer (ELR) and fibrin were prepared with a range on polymer concentrations and ELR-to-fibrin ratios. The correlation between SEM micrographs, porosity, swelling ratio and rheological properties was discussed and a poroelastic mechanism was suggested to explain the mechanical behavior of the hybrid gels. Applicability as scaffold material for cardiovascular tissue engineering was shown by the realization of cell-laden matrixes which supported the synthesis of collagens as revealed by immunohistochemical analysis. As a proof of concept, a tissue-engineered heart valve was fabricated by injection moulding and cultivated in a bioreactor for 3 weeks under dynamic conditions. Tissue analysis revealed production of collagen I and III, fundamental proteins for cardiovascular constructs.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA244U13

Universal applicator for digitally-controlled pressing force and impact velocity insertion of microneedles into skin

Microneedle technologies have been developed for dermal drug and vaccine delivery, including hollow-, solid-, coated-, and dissolving microneedles. Microneedles have been made in many different geometries and of many different materials, all of which may influence their skin-penetrating ability. To ensure reproducible and effective drug and vaccine delivery via microneedles, the optimal insertion parameters should be known. Therefore, a digitally-controlled microneedle applicator was developed to insert microneedles into the skin via impact insertion (velocity) or via pressing force insertion. Six microneedle arrays with different geometries and/or materials were applied onto ex vivo human skin with varying velocities or pressing forces. Penetration efficiency and delivered antigen dose into the skin after application of microneedles were determined. In general, microneedles pierced the skin more efficiently when applied by impact application as compared to application via pressing force. However, the angle of application of the applicator on the skin can affect the velocity of the impact, influencing the penetration efficiency of microneedles. Regarding the antigen delivery into the skin, the delivered dose was increasing by increasing the velocity or pressure, and thus, increasing the penetration efficiency. These data demonstrate that an applicator is an important tool to determine optimal application conditions with ex vivo human skin

Development of PLGA nanoparticle loaded dissolving microneedles and comparison with hollow microneedles in intradermal vaccine delivery

Skin is an attractive but also very challenging immunisation site for particulate subunit vaccines. The aim of this study was to develop hyaluronan (HA)-based dissolving microneedles (MNs) loaded with PLGA nanoparticles (NPs) co-encapsulating ovalbumin (OVA) and poly(I:C) for intradermal immunisation. The NP:HA ratio used for the preparation of dissolving MNs appeared to be critical for the quality of MNs and their dissolution in ex vivo human skin. Asymmetrical flow field-flow fractionation and dynamic light scattering were used to analyse the NPs released from the MNs in vitro. Successful release of the NPs depended on the drying conditions during MN preparation. The delivered antigen dose from dissolving MNs in mice was determined to be 1 µg OVA, in NPs or as free antigen, by using near-infrared fluorescence imaging. Finally, the immunogenicity of the NPs after administration of dissolving MNs (NP:HA weight ratio 1:4) was compared with that of hollow MN-delivered NPs in mice. Immunization with free antigen in dissolving MNs resulted in equally strong immune responses compared to delivery by hollow MNs. However, humoral and cellular immune responses evoked by NP-loaded dissolving MNs were inferior to those elicited by NPs delivered through a hollow MN. In conclusion, we identified several critical formulation parameters for the further development of NP-loaded dissolving MNs

Determination of the Shear Force at the Balance between Bacterial Attachment and Detachment in Weak-Adherence Systems, Using a Flow Displacement Chamber▿

We introduce a procedure for determining shear forces at the balance between attachment and detachment of bacteria under flow. This procedure can be applied to derive adhesion forces in weak-adherence systems, such as polymer brush coatings, which are currently at the center of attention for their control of bacterial adhesion and biofilm formation

Bacterial adhesion and growth on a polymer brush-coating

Biomaterials-related infections pose serious problems in implant surgery, despite the development of non-adhesive coatings. Non-adhesive coatings, like polymer brush-coatings, have so far only been investigated with respect to preventing initial bacterial adhesion, but never with respect to effects on kinetics of bacterial growth. Here, we compare adhesion and 20 h growth of three bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa) on pristine and brush-coated silicone rubber in a parallel plate flow chamber. Brush-coatings were made using a tri-block copolymer of polyethylene oxide (PEO) and polypropylene oxide (PPO). Brush-coatings prevented adhesion of staphylococci to below 5 x 105 cm(-2) after 30 min, which is a 10-fold reduction compared to pristine silicone rubber. Biofilms grew on both brush-coated and pristine silicone rubber, while the viability of biofilms on brush-coatings was higher than on pristine silicone rubber. However biofilms on, brush-coatings developed more slowly and detached almost fully by high fluid shear. Brush-coating remained non-adhesive after S. epidermidis biofilm formation and subsequent removal whereas a part of its functionality was lost after removal of S. aureus biofilms. Adhesion, growth and detachment of P. aeruginosa were not significantly different on brush-coatings as compared with pristine silicone rubber, although here too the viability of biofilms on brush-coatings was higher. We conclude that polymer brush-coatings strongly reduce initial adhesion of staphylococci and delay their biofilm growth. In addition, biofilms on brush-coatings are more viable and easily removed by the application of fluid shear. (C) 2008 Elsevier Ltd. All rights reserved

Determination of a setup correction function to obtain adsorption kinetic data at stagnation point flow conditions

This paper is the first report on the characterization of the hydrodynamic conditions in a flow cell designed to study adsorption processes by spectroscopic ellipsometry. The resulting cell enables combining the advantages of in situ spectroscopic ellipsometry with stagnation point flow conditions. An additional advantage is that the proposed cell features a fixed position of the " inlet tube" with respect to the substrate, thus facilitating the alignment of multiple substrates. Theoretical calculations were performed by computational fluid dynamics and compared with experimental data (adsorption kinetics) obtained for the adsorption of polyethylene glycol to silica under a variety of experimental conditions. Additionally, a simple methodology to correct experimental data for errors associated with the size of the measured spot and for variations of mass transfer in the vicinity of the stagnation point is herein introduced. The proposed correction method would allow researchers to reasonably estimate the adsorption kinetics at the stagnation point and quantitatively compare their results, even when using different experimental setups. The applicability of the proposed correction function was verified by evaluating the kinetics of protein adsorption under different experimental conditions. © 2010.Fil: Mora, Maria F.. The University of Texas at San Antonio; Estados UnidosFil: Reza Nejadnik, M.. The University of Texas at San Antonio; Estados UnidosFil: Baylon Cardiel, Javier L.. Tecnológico de Monterrey; MéxicoFil: Giacomelli, Carla Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Garcia, Carlos D.. The University of Texas at San Antonio; Estados Unido

Impact of Excipient Extraction and Buffer Exchange on Recombinant Monoclonal Antibody Stability

The foundation of a biosimilar manufacturer’s regulatory filing is the demonstration of analytical and functional similarity between the biosimilar product and the pertinent originator product. The excipients in the formulation may interfere with characterization using typical analytical and functional techniques during this biosimilarity exercise. Consequently, the producers of biosimilar products resort to buffer exchange to isolate the biotherapeutic protein from the drug product formulation. However, the impact that this isolation has on the product stability is not completely known. This study aims to elucidate the extent to which mAb isolation via ultrafiltration-diafiltration-based buffer exchange impacts mAb stability. It has been demonstrated that repeated extraction cycles do result in significant changes in higher-order structure (red-shift of 5.0 nm in fluorescence maxima of buffer exchanged samples) of the mAb and also an increase in formation of basic variants from 19.1 to 26.7% and from 32.3 to 36.9% in extracted innovator and biosimilar Tmab samples, respectively. It was also observed that under certain conditions of tertiary structure disruptions, Tmab could be restabilized depending on formulation composition. Thus, mAb isolation through extraction with buffer exchange impacts the product stability. Based on the observations reported in this paper, we recommend that biosimilar manufacturers take into consideration these effects of excipients on protein stability when performing biosimilarity assessments

Adsorption of Pluronic F-127 on Surfaces with Different Hydrophobicities Probed by Quartz Crystal Microbalance with Dissipation

Triblock copolymers of polyethylene oxide (PEO) and polypropylene oxide (PPO), that is, PEO(n)-PPO(m)-PEO(n), better known as Pluronic can adsorb to surfaces in either a pancake or a brushlike configuration. The brushlike configuration is advantageous in numerous applications, since it constitutes a surface repellent to proteins and microorganisms. The conformation of the adsorbed Pluronic layer depends on the hydrophobicity of the substratum surface, but the hydrophobicity threshold above which a brushlike conformation is adopted is unknown. Therefore, the aim of this study is to investigate Pluronic F-127 adsorption on surfaces with different hydrophobicities using a quartz crystal microbalance with dissipation. Adsorption in a brushlike conformation occurred on surfaces with a water contact angle above 80 degrees, as inferred from the thickness, viscosity, and elasticity of the adsorbed layer. The concentration of Pluronic F-127 in solution affected only the kinetics of adsorption and not the final layer thickness or conformation of adsorbed Pluronic molecules

Bacterial colonization of polymer brush-coated and pristine silicone rubber implanted in infected pockets in mice

Curing biomaterial-associated infection (BAI) frequently includes antibiotic treatment, implant removal and re-implantation. However, revision implants are at a greater risk of infection as they may attract bacteria from their infected surroundings. Polymer brush-coatings attract low numbers of bacteria, but the virtue of polymer brush-coatings in vivo has seldom been investigated. Here, we determine the possible benefits of polymer brush-coated versus pristine silicone rubber in revision surgery, using a murine model. BAI was induced in 26 mice by subcutaneous implantation of silicone rubber discs with a biofilm of Staphylococcus aureus Xen29. During the development of BAI, half of the mice received rifampicin/vancomycin treatment. After 5 days, the infected discs were removed from all mice, and either a polymer brush-coated or pristine silicone rubber disc was re-implanted. Revision discs were explanted after 5 days, and the number of cfu cultured from the discs and the surrounding tissue was determined. None of the polymer brush-coated discs after antibiotic treatment appeared colonized by staphylococci, whereas 83% of the pristine silicone rubber discs were re-infected. Polymer brush-coated discs also showed reduced colonization rates in the absence of antibiotic treatment when compared with pristine silicone rubber discs. Tissue surrounding the discs was culture-positive in all cases. Polymer brush-coatings are less prone to re-infection than pristine silicone rubber when used in revision surgery, i.e. when implanted in a subcutaneous pocket infected by a staphylococcal BAI. Antibiotic pre-treatment during the development of BAI hardly had any effect in preventing the colonization of pristine silicone rubber