Effects of brief milling and acid treatment on two ordered and disordered kaolinite structures

The structural characteristics of well-ordered kaolinite (K1) and poorly ordered kaolinite (K2) after the ¼ h milling procedures, continuing acid activation with 2 M hydrochloric acid and intercalation ability with urea were assessed. Kaolinite samples were examined by X-ray powder diffraction, thermogravimetry, infrared spectroscopy analysis and specific surface area measurement. Kaolinite K1 contained a slightly higher portion of particles <2 μm (38 vol.%) than K2 (31 vol.%) increasing after jet milling (to 92 vol.% and 54 vol.%, respectively), but decreasing slightly after ball milling (to the 37 vol.% and 26 vol.%, respectively). The acid treatment contributed to a narrower particle size distribution, increased value of the surface area and dehydroxylation temperature and improved the structural order of poorly ordered kaolinites. Maximum surface area SSA = 45 m2g− 1 was measured for K2 after ball milling and treatment with hydrochloric acid. Treatment of kaolinites with hydrochloric acid supports their ability to intercalate urea and exfoliate, while the mechanical millings adversely affected intercalation urea. The SSA 9.8 and 20.5 m2g− 1 of K1 and K2, respectively, changed after: (1) exfoliation to 21.0 and 34.1 m2g− 1, respectively, (2) jet milling and exfoliation to 38.0 and 42.0 m2g− 1, respectively, (3) ball milling and exfoliation to 20.3 and 34.4 m2g− 1, respectively, and (4) ball milling, acid treatment and exfoliation to 40.3 and 46.7 m2g− 1, respectively.Web of Science541767

Novel LDPE/vermiculite/ciclopiroxolamine hybrid nanocomposites: Structure, surface properties, and antifungal activity

The increasing number of indwelling medical materials and devices are connected with infections caused by yeast, especially Candida albicans. This pathogen produces biofilms on synthetic materials, which facilitates adhesion of the organisms to devices and renders them relatively refractory to medical therapy. Since antimicrobial polymer nanocomposites present one of the promising possibilities, this study explores a new approach to achieving this goal by developing nanocomposite based on low density polyethylene (LDPE) with clay mineral vermiculite as an active carrier for antifungal compound. The set of LDPE/clay nanocomposite with increasing amount of antifungal nanofiller was prepared by melt compounding procedure. As antifungal agent was selected generally used active substance ciclopiroxolamine and this compound was loaded into natural vermiculite through ultrasound technique. The structure of all prepared samples was studied by X-ray diffraction analysis and Fourier transforms infrared spectroscopy. Further thermal properties of polyethylene/clay nanocomposites were investigated by thermogravimetric analysis and the surface properties were evaluated by light optical microscopy, scanning electron microscopy and atomic force microscopy. From mentioned characteristics, we conclude that presence of nanofiller in LDPE primarily causes shift of thermal degradation to higher temperatures and increasing of microhardness. All prepared LDPE nanocomposites possess an excellent and prolonged antifungal activity against Candida albicans.Ministry of Education, Youth and a Sports of Czech Republic [SP2019/24, SP2020/08

Organovermiculite nanofillers in polypropylene

Vermiculite (VER) was exfoliated to be used as organovermiculite nanofiller(ODA/VER) for polypropylene (PP)/VER nanocomposites. We used three procedures. PI: low-temperature intercalation of melted octadecylamine (ODA) led to the regular bilayer arrangement of organic molecules in the interlayer space. P2: mechanical exfoliation of ODA/VER by jet milling decreased the crystallite size. P3: chemical exfoliation using an oxidizing agent potassium persulfate and subsequent intercalation with ODA created a mixture of monolayer and bilayer arrangements of organic cations in the interlayer. The thermal compounding of the organovermiculites (4 wt.%) with maleated PP at 30 and 50 rpm caused the partial deintercalation of the organovermiculite and organovermiculite pretreated with the oxidizing agent. The jet milled ODA/VER was very well dispersed within PP matrix. Thermal stability of PP and PP/VER nanocomposites with differently exfoliated ODA/VER nanofillers was evaluated by thermogravimetric analysis. (C) 2008 Elsevier B.V. All rights reserved

Organovermiculite nanofillers in polypropylene

Vermiculite (VER) was exfoliated to be used as organovermiculite nanofiller (ODA/VER) for polypropylene (PP)/VER nanocomposites. We used three procedures. P1: low-temperature intercalation of melted octadecylamine (ODA) led to the regular bilayer arrangement of organic molecules in the interlayer space. P2: mechanical exfoliation of ODA/VER by jet milling decreased the crystallite size. P3: chemical exfoliation using an oxidizing agent potassium persulfate and subsequent intercalation with ODA created a mixture of monolayer and bilayer arrangements of organic cations in the interlayer. The thermal compounding of the organovermiculites (4 wt.%) with maleated PP at 30 and 50 rpm caused the partial deintercalation of the organovermiculite and organovermiculite pretreated with the oxidizing agent. The jet milled ODA/VER was very well dispersed within PP matrix. Thermal stability of PP and PP/VER nanocomposites with differently exfoliated ODA/VER nanofillers was evaluated by thermogravimetric analysis

Vermiculite filler for polymeric nanocomposites: thermal and dispersion study

The demand of nanocomposites for filler properties which is expected utilization. Natural minerals are keeping one of the prior positions in that significance. The thermal properties and strength of the requested properties expected to be improved for polymeric materials. Modification of that layered materials is still necessary to assure the compatibility of the filler with polymer with non-polar character. The organically modified montmorillonite is still the most frequently studied mineral for the application as the filler. Comparing montmorillonite and vermiculite we can note the difference in layer charge of silicate layer. Thus the vermiculite with higher charge could be more stable. Modification of jet milled vermiculite with amine and phosphonium salts using thermal treatment was performed using 10% of organic amount. The changes of interlayer space of samples after intercalation and nanocomposites were studied using X-ray diffraction analysis. Higher degradation temperature for nanocomposites with vermiculite was defined using thermogravimetry

Synthesis and antimicrobial activity of polyethylene/chlorhexidine/vermiculite nanocomposites

The set of polyethylene/clay nanocomposites with increasing amount of antimicrobial nanofiller (3, 6 and 10 wt%) was prepared by melt compounding procedure. The antimicrobial drug chlorhexidine diacetate was loaded into natural clay mineral vermiculite and also to its monoionic sodium form and then these organoclay nanofillers were incorporated into polymeric matrix. The structure of prepared organoclays and nanocomposites was studied by X-ray diffraction analysis and Fourier transforms infrared spectroscopy. Further thermal properties of polyethylene/clay nanocomposites were investigated by thermogravimetric analysis and the surface roughness was evaluated by atomic force microscopy. Finally, organoclays and polyethylene/clay nanocomposites were tested for antimicrobial activity against bacterial strains Staphylococcus aureus, Escherichia coli and yeast Candida albicans. Prepared samples showed a very good antimicrobial activity with long lasting effect. In the case of polyethylene/clay nanocomposites we observed some differences in antimicrobial action between two used antimicrobial nanofillers. These results suggested great potential of using the polymer/clay nanocomposites in the wide range of antimicrobial applications.Web of Science1952933292

Raw data for the article "In vitro culture of leukemic cells in collagen scaffolds and carboxymethylcellulose-polyethylene glycol gel"

Uncropped original micrographs created for figures of our article submitted to PeerJ

Integrated epigenomic and transcriptomic analysis reveals TP63 as a novel player in clinically aggressive chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) stereotyped subsets #6 and #8 include cases expressing unmutated B cell receptor immunoglobulin (BcR IG) (U-CLL). Subset #6 (IGHV1-69/IGKV3-20) is less aggressive compared to subset #8 (IGHV4-39/IGKV1(D)-39) which has the highest risk for Richter's transformation among all CLL. The underlying reasons for this divergent clinical behavior are not fully elucidated. To gain insight into this issue, here we focused on epigenomic signatures and their links with gene expression, particularly investigating genome-wide DNA methylation profiles in subsets #6 and #8 as well as other U-CLL cases not expressing stereotyped BcR IG. We found that subset #8 showed a distinctive DNA methylation profile compared to all other U-CLL cases, including subset #6. Integrated analysis of DNA methylation and gene expression revealed significant correlation for several genes, particularly highlighting a relevant role for the TP63 gene which was hypomethylated and overexpressed in subset #8. This observation was validated by quantitative PCR, which also revealed TP63 mRNA overexpression in additional nonsubset U-CLL cases. BcR stimulation had distinct effects on p63 protein expression, particularly leading to induction in subset #8, accompanied by increased CLL cell survival. This pro-survival effect was also supported by siRNA-mediated downregulation of p63 expression resulting in increased apoptosis. In conclusion, we report that DNA methylation profiles may vary even among CLL patients with similar somatic hypermutation status, supporting a compartmentalized approach to dissecting CLL biology. Furthermore, we highlight p63 as a novel prosurvival factor in CLL, thus identifying another piece of the complex puzzle of clinical aggressiveness. What's new? In chronic lymphocytic leukemia (CLL), cases with unmutated immunoglobulin receptors (U-CLL) are generally associated with inferior outcome, albeit still displaying considerable heterogeneity. Might such differences in CLL progression be explained by epigenetics? In this study, the authors found that an unusually aggressive subset of CLLs called subset #8 has a distinctive DNA-methylation profile. They also found that p63 is a novel pro-survival factor for CLL cells. These molecular studies may lead to new prognostic biomarkers, and possibly new therapeutic targets, for CLL