Thermogelation properties of poly(N-isopropylacrylamide) – block – poly(ethylene glycol) – block – poly(N-isopropylacrylamide) triblock copolymer aqueous solutions

Low polydispersity PNIPAM–PEG–PNIPAM triblock copolymers with PEG blocks of 1–6 kDa and PNIPAM chains of 5–30 kDa were synthesized and their thermogelation behavior in aqueous solution as a function of their composition and block length was investigated for the first time. DSC, dynamic rheometry and the tube inverting method were employed to characterize the gelation process at various polymer concentrations, and their results were compared. The thermogelation process depended mainly on the length of both PNIPAM and PEG blocks. Both association and aggregation temperatures of the PNIPAM chains decreased with the MW of PNIPAM and increased with the length of the PEG block. The amplitude of these effects depended on the molecular weights of the blocks forming the copolymer as a consequence of the partial mixing of PNIPAM and PEG chains during the association/aggregation process, while the overall hydrophilicity of the entire copolymer played only a minor role. The length of the PEG block proved also to be the most important factor for the preparation of a stable gel in 20 wt.% solutions, while the hydrophilic groups/hydrophobic groups ratio had no importance.     

A highly stable polyethylene glycol-conjugated human single-chain antibody neutralizing granulocyte-macrophage colony stimulating factor at low nanomolar concentration

GM-CSF (granulocyte-macrophage colony stimulating factor) plays a central role in inflammatory processes. Treatment with antibodies neutralizing murine GM-CSF showed significant therapeutic effects in mouse models of inflammatory diseases. We constructed by phage display technology a human scFv, which could potently neutralize human GM-CSF. At first, a human V(L) repertoire was combined with the V(H) domain of a parental GM-CSF-neutralizing rat antibody. One dominant rat/human scFv clone was selected, neutralizing human GM-CSF with an IC50 of 7.3 nM. The human V(L) of this clone was then combined with a human V(H) repertoire. The latter preserved the CDR 3 of the parental rat V(H) domain to retain binding specificity. Several human scFvs were selected, which neutralized human GM-CSF at low nanomolar concentrations (IC50 > or = 2.6 nM). To increase serum half-life, a branched 40 kDa PEG-polymer was coupled to the most potent GM-CSF-neutralizing scFv (3077) via an additional C-terminal cysteine. PEG conjugation had a negligible effect on the in vitro neutralizing potential of the scFv, although it caused a significant drop in binding affinity owing to a reduced on-rate. It also significantly increased the stability of the scFv at elevated temperatures. In mouse experiments, the PEGylated scFv 3077 showed a significantly prolonged elimination half-life of 59 h as compared with 2 h for the unconjugated scFv version. PEGylated scFv 3077 is a potential candidate for development of a novel antibody therapy to treat pro-inflammatory human diseases.     

Treatment with Mesenchymal Stromal Cells Overexpressing Fas-Ligand Ameliorates Acute Graft-versus-Host Disease in Mice

Allogeneic hematopoietic cell transplantation (allo-HCT) has the potential to cure malignant and non-malignant hematological disorders, but because of the serious side effects of this intervention its applications are limited to a restricted number of diseases. Graft-versus-host disease (GvHD) is the most frequent complication and the leading cause of mortality and morbidity following allo-HCT. It results from the attack of the transplanted T cells from the graft against the cells of the recipient. There is no clear treatment for this severe complication. Due to their immunomodulatory properties, mesenchymal stromal cells (MSC) have been proposed to treat GvHD, but the results did not meet expectations. We have previously showed that the immunomodulatory effect of the MSC was significantly enhanced through adenoviral-mediated overexpression of FasL. In this study, we have tested the properties of FasL-overexpressing MSC in vivo, in a mouse model for acute GvHD. We found that treatment with FasL-overexpressing MSC delayed the onset of the disease and increased survival of the mice.     

Technological, Economic, and Environmental Optimization of Aluminum Recycling

The four strategic directions (referring to the entire life cycle of aluminum) are as follows: production, primary use, recycling, and reuse. Thus, in this work, the following are analyzed and optimized: reducing greenhouse gas emissions from aluminum production, increasing energy efficiency in aluminum production, maximizing used-product collection, recycling, and reusing. According to the energetic balance at the gaseous environment level, the conductive transfer model is also analyzed through the finished elements method. Several principles of modeling and optimization are presented and analyzed: the principle of analogy, the principle of concepts, and the principle of hierarchization. Based on these principles, an original diagram model is designed together with the corresponding logic diagram. This article also presents and analyzes the main benefits of aluminum recycling and reuse. Recycling and reuse of aluminum have the main advantage that it requires only about 5% of energy consumed to produce it from bauxite. The aluminum recycling and production process causes the emission of pollutants such as dioxides and furans, hydrogen chloride, and particulate matter. To control these emissions, aluminum recyclers are required to comply with the National Emission Standards for Hazardous Air Pollutants for Secondary Aluminum Production. The results of technological, economic, and ecological optimization of aluminum recycling are based on the criteria function’s evaluation in the modeling system.     

Valorization of Gleditsia triacanthos Invasive Plant Cellulose Microfibers and Phenolic Compounds for Obtaining Multi-Functional Wound Dressings with Antimicrobial and Antioxidant Properties

Gleditsia triacanthos is an aggressive invasive species in Eastern Europe, producing a significant number of pods that could represent an inexhaustible resource of raw material for various applications. The aim of this study was to extract cellulose from the Gleditsia triacanthos pods, characterize it by spectrophotometric and UHPLC–DAD-ESI/MS analysis, and use it to fabricate a wound dressing that is multi-functionalized with phenolic compounds extracted from the leaves of the same species. The obtained cellulose microfibers (CM) were functionalized, lyophilized, and characterized by ATR-FTIR and SEM. The water absorption and retention capacity as well as the controlled release of phenolic compounds with antioxidant properties evaluated in temporal dynamics were also determined. The antimicrobial activity against reference and clinical multi-drug-resistant Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloacae, Candida albicans, and Candida parapsilosis strains occurred immediately after the contact with the tested materials and was maintained for 24 h for all tested microbial strains. In conclusion, the multi-functionalized cellulose microfibers (MFCM) obtained from the reproductive organs of an invasive species can represent a promising alternative for the development of functional wound dressings with antioxidant and antimicrobial activity, as well as being a scalable example for designing cost-effective, circular bio-economy approaches to combat the accelerated spread of invasive species.     

K2 Transfection System Boosts the Adenoviral Transduction of Murine Mesenchymal Stromal Cells

Adenoviral vectors are important vehicles for delivering therapeutic genes into mammalian cells. However, the yield of the adenoviral transduction of murine mesenchymal stromal cells (MSC) is low. Here, we aimed to improve the adenoviral transduction efficiency of bone marrow-derived MSC. Our data showed that among all the potential transduction boosters that we tested, the K2 Transfection System (K2TS) greatly increased the transduction efficiency. After optimization of both K2TS components, the yield of the adenoviral transduction increased from 18% to 96% for non-obese diabetic (NOD)-derived MSC, from 30% to 86% for C57BL/6-derived MSC, and from 0.6% to 63% for BALB/c-derived MSC, when 250 transduction units/cell were used. We found that MSC derived from these mouse strains expressed different levels of the coxsackievirus and adenovirus receptors (MSC from C57BL/6≥NOD>>>BALB/c). K2TS did not increase the level of the receptor expression, but desensitized the cells to foreign DNA and facilitated the virus entry into the cell. The expression of Stem cells antigen-1 (Sca-1) and 5′-nucleotidase (CD73) MSC markers, the adipogenic and osteogenic differentiation potential, and the immunosuppressive capacity were preserved after the adenoviral transduction of MSC in the presence of the K2TS. In conclusion, K2TS significantly enhanced the adenoviral transduction of MSC, without interfering with their main characteristics and properties.     

Two dimensional time-frequency analysis based eigenvalue decomposition applied to image watermarking

An application of two-dimensional time-frequency analysis and corresponding two-dimensional eigenvalue decomposition for image watermarking purpose is proposed. The eigenvalue decomposition is used to provide a criterion for watermarking coefficients selection. It is primarily used to select pixels suitable for watermarking that belong to busy image regions. The watermark embedding is performed in the space/spatial-frequency domain by using middle frequency components, whose number is determined from the eigenvalue decomposition, as well. In order to provide its imperceptibility, watermark is modelled and adapted to the local frequency content of each considered pixel. For an efficient watermark modelling procedure, the concept of space-varying filtering is employed. Furthermore, the watermark detection is done within the space/spatial-frequency domain, which facilitates detection process due to the larger number of coefficients comparing to the space or frequency domain, separately. The efficiency of the proposed procedure and its robustness in the presence of various attacks is proven on the examples.     

Structural,dielectric, and piezoelectric properties of fine-grained NBT–BT0.11 ceramic derived from gel precursor

(Na_1/2Bi_1/2)TiO₃ doped in situ with 11 mol% BaTiO₃ (NBT–BT_0.11) powders were synthesized by a sol–gel method, and the electrical properties of the resulting ceramics were investigated. The powders consisting of uniform and fine preliminary particles of about 50 nm were prepared by calcining the gel precursor at 700 °C. (Na_1/2Bi_1/2)_0.89Ba_0.11TiO₃ ceramics, sintered at temperatures up to 1150 °C have a rhombohedral symmetry, while the ceramic sintered at 1200 °C exhibits a tetragonal crystalline structure. The ceramics show high dielectric constant (?_r ～ 5456), dielectric loss of 0.02, depolarization temperature T_d ～ 110 °C and temperature corresponding to the maximum value of dielectric constant T_m ～ 262 °C. The dielectric constant (?₃₃) and the piezoelectric constant (d₃₃) attain the maximum values of 924 and 13 pC/N, respectively, while the electromechanical coupling factor (k_p) value is 0.035. The NBT–BT_0.11 ceramics derived from sol–gel present high mechanical quality factor (Q_m ～ 860). The dielectric and piezoelectric properties values of NBT–BT_0.11 ceramics derived from sol–gel are smaller than those of samples produced by the conventional solid state reaction method, due to the grains size and oxygen vacancies that generate dipolar defects.