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Multifunctional biodegradable polymer/clay nanocomposites with antibacterial properties in drug delivery systems

Rapacz-Kmita Alicja, Szaraniec Barbara, Mikołajczyk Maciej, Stodolak-Zych Ewa, Dzierzkowska Ewa, Gajek Marcin, Dudek Piotr

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 2

83--92

EN

Purpose: The aim of this study was to investigate the possibility of intercalation of gentamicin and neomycin in montmorillonite (MMT) nanofillers, as well as to study the in vitro antimicrobial properties of nanocomposite films containing a small amount of thus obtained nanofillers. Methods: The polylactide matrix (PLA) nanocomposite films with drug-intercalated montmorillonite fillers were obtained by casting after intercalation of drugs in aqueous solutions. The efficiency of intercalation has been confirmed by X-ray diffraction (XRD) and Zeta potential measurements. The materials were studied for surface wettability, roughness and mechanical properties during 6 weeks of incubation in phosphate buffer saline, and their bactericidal activity was tested against Escherichia coli bacteria before and after 6 weeks of incubation in distilled water at 37 C. The presence of antibiotics during the incubation was monitored by conductivity and pH measurements. Results: The results indicate that nanocomposite polylactide films with montmorillonite filler intercalated with gentamicin and neomycin tend to degrade faster that their counterparts with non-intercalated fillers, which affects their mechanical properties. However, drug intercalation provided an antibacterial activity, which was confirmed by the presence of zones inhibiting the growth of Gram-negative bacteria for both antibiotics. It was also confirmed that the interaction of antibiotics with clay and polymer matrix did not adversely affect this bactericidal effect. Conclusions: Montmorillonite can be successfully intercalated with both gentamicin and neomycin, and then used as active filler for polylactide films having very good antibacterial properties, therefore their use in biomedical applications can be significantly expanded.

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The influence of alkali concentration and temperature on chemical activation of halloysite

Maziarz P.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 1

97--98

EN

The influence of alkali activation on clay minerals is not thoroughly investigated, particularly in terms of its impact on adsorption possibilities of clay minerals. One of the studied applications of base treated clay minerals was to control sustained drug release (Wang et al. 2013). Based on the recent studies, the base treatment can cause changes in structure, texture, and morphology of clay minerals. These changes are related to partial dissolution of layered structure and subsequent release of Si and Al to the solution (White et al. 2012, Yuan et al. 2015). This modification can be especially promising in case of halloysite, which is a clay mineral revealing unique nanoscale tubular morphology. Previous studies indicate that selective dissolution of halloysite’s aluminosilicate layers can lead to opening of the tubes interior (lumen) (Wang et al. 2013). This type of structural alteration can influence utilization possibilities of halloysite. Therefore, the aim of this work is to investigate the influence of alkali concentration and reaction temperature on the halloysite structure. The halloysite used in the studies came from Polish deposit located in Dunino, near Legnica (SW Poland) which is constantly exploited. The base activation was carried out using sodium hydroxide (NaOH). Firstly, the effect of NaOH concentration on activation efficiency was investigated. The experiments were carried out for the concentration range from 0.01 to 5.0 mol/L at room temperature. Additionally, for the 1.0 mol/L concentration the experiments were performed at temperatures of 50°C, 60°C, 70°C, 80°C and 90°C. the suspensions consisting of 2 g of halloysite and 50 mL of appropriate solution were mixed for 24 h using magnetic stirrer. Subsequently, the samples were washed with water and dried at 60°C. The prepared materials were characterized using XRD and FTIR methods. The IR results revealed that the concentrations of NaOH below 5 mol/L at room temperature did not cause significant changes in spectra of the tested samples. However, the results of experiments carried out in the temperature range from 60°C to 90°C showed that the temperature of the suspension can significantly affect the alkali activation. Based on the IR spectra the reaction at 50°C did not alter the structure of halloysite, in contrast to 60°C, 70°C, 80°C and 90°C temperatures. The changes of relative intensities of the bands associated with inner surface hydroxyls were observed in the 3700–3600 cm −1 region. These results suggest a gradual removal of inner surface hydroxyls, with the temperature increase. The results also indicated a gradual increase of intensity and broadening of the band with the maximum at 3430 cm −1 and 1647 cm −1 which were attributed to H–O–H stretching and bending vibrations of adsorbed water, respectively. It can be also observed that base treatment at higher temperature also caused structural changes within the aluminosilicate framework of halloysite. The frequency shift and broadening of bands assigned to Si-O-Si stretching (1033 cm −1 , 1008 cm −1 ) and bending (54 0 cm −1 ) vibrations were observed. The perturbations and/or removal of Al-O-H was confirmed by the decrease of bands intensity assigned to bending vibrations at 936 cm −1 and 914 cm −1 The higher temperatures resulted in an appearance of new bands at 1470 cm −1 and 1400 cm −1 associated with carbonates. These bands become more evident with the increase in temperature. The XRD results indicated the formation of additional crystalline phases: sodium aluminum silicate, hydrated sodium carbonates and sodium aluminum carbonate silicate. The presence of carbonates in the samples was confirmed also by FTIR spectra. It was suspected that the presence of carbonate may be related to uptake of atmospheric CO 2 and its reaction with NaOH in accordance with earlier reports by Slaty et al. (2013) and Aldabsheh et al. (2015). The results of this work suggest that different variations of the activation conditions should be examined, to find the optimal temperature for alkaline treatment that leads to an increase in the lumen diameter of halloysite, but does not affect the mineral morphology.

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Elastic properties of some clay minerals

Vyzhva S. A., Prodayvoda G. T., Vyzhva A. S.

Nafta-Gaz

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2014

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R. 70, nr 11

743--756

EN

A new method for the quantitative estimation of the elastic properties of clay minerals based on the principles of crystal-chemical systematization of clay minerals elastic properties was developed. An accurate mathematical method has been devised to approximate elastic properties of a random symmetry medium to those of a similar transversely isotropic elastic medium. A first successful attempt was made at a quantitative assessment of the elastic constants of all clay mineral constituents in transversely isotropic approximation, which fully agrees with experimental data on these minerals. Extensive research has been carried out into the anisotropy parameters of clay mineral elastic waves and their correlation with the structural features of minerals. This method can be used for approximating the elastic constants of other rock-forming minerals.

PL

Opracowano nową metodę oceny ilościowej sprężystych własności minerałów ilastych w oparciu o zasady krystaliczno-chemicznej systematyzacji tych własności. Nowa, dokładna matematyczna metoda ma na celu przybliżenie własności sprężystych ośrodka o losowej symetrii do tych o podobnym sprężystym ośrodku poprzecznie izotropowym. Pierwszej udanej próby dokonano przy ilościowej ocenie stałych sprężystych wszystkich komponentów minerałów ilastych w poprzecznie izotropowym przybliżeniu, co jest w pełni zgodne z danymi eksperymentalnymi dotyczącymi tych minerałów. Przeprowadzono wszechstronne badanie parametrów anizotropowych fal sprężystych minerałów ilastych i ich korelacji ze strukturalnymi cechami minerałów. Metoda ta może zostać wykorzystana do przybliżenia stałych sprężystych innych minerałów w formacjach skalnych.

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Zastosowanie minerałów ilastych do usuwania metali ciężkich

Mlaś A., Petryniak J., Ryznar A., Sobolewska P., Warchoł J.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2011

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z. 58, nr 2

177-195

PL

Artykuł stanowi przegląd literatury na temat sorpcji jonów metali ciężkich z roztworów wodnych na minerałach ilastych. Przedstawiono charakterystykę najważniejszych przedstawicieli należących do tej grupy minerałów: kaolinitu, montmorillonitu, bentonitu oraz chlorytu. Omówiono właściwości fizyczne, elektrochemiczne i zastosowanie naturalnych oraz modyfikowanych minerałów ilastych. Porównano efektywność usuwania jonów metali ciężkich na wybranych sorbentach naturalnych i poddanych modyfikacji.

EN

The article presents a review of heavy metal ions removal adsorption on natural clay minerals. The characteristics of the mineral specifications such as montmorillonite, bentonite, kaolinite and chlorite has been presented. The physical, electrochemical properties as well as a practical application of natural and modified clay minerals has been discussed. The adsorption affinity of natural and chemical modified clay minerals towards heavy metals ions has been compared.

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Badania mineralogiczno-petrograficzne i ługownicze prób soli ze złoża Sorkol (Kazachstan)

Nowińska-Jarzębińska Justyna, Walczak-Torba Natalia

Przegląd Solny

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2021/2022

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T. 16

92--103

PL

Złoże soli kamiennej Sorkol znajduje się w południowo-wschodniej części Republiki Kazachstanu, w obwodzie żambylskim, w rejonie Sarysu. Obszar ten charakteryzuje się klimatem umiarkowanym, suchym, skrajnie kontynentalnym, o dużych amplitudach temperatur dobowych. Tak niekorzystne warunki klimatyczne doprowadziły do pustynnienia tego obszaru i znacząco przyspieszyły ewaporację płytkich zbiorników zasilanych przez wysoko zmineralizowane wody. Wszystko to poskutkowało powstaniem lokalnych salin na powierzchni. Badane sole znajdują się w basenie sedymentacyjnym Chu-Sarysu, w serii permskich ewaporatów na głębokości ok. 240 do ok. 520 m p.p.t., a ich łączna miąższość wynosi około 280 m. W skład tej serii wchodzi sól drobnokrystaliczna, po grubokrystaliczną, a cały profil jest mocno zanieczyszczony skonsolidowanymi minerałami ilastymi, nazywanymi lokalnie argillitem oraz wodorotlenkami żelaza, które znacząco wpłyną na eksploatację otworową tych soli. Sole ze złoża Sorkol posiadają zupełnie odmienne cechy fizyko-chemiczne niż dotychczas opisywane w literaturze polskiej sole ze złóż europejskich wieku permskiego.

EN

The Sorkol rock salt deposit is located in the south-eastern part of the Republic of Kazakhstan, in the Żambyl district, the Sarysu region. This area is characterized by a temperate, dry, extremely continental climate with large diurnal temperature variations. Such extreme and unfavorable climatic conditions led to the desertification of this area and significantly accelerated the evaporation of shallow reservoirs fed by highly mineralized waters, which resulted in the formation of local salines. Analysed salts are located in the Chu-Sarysu sedimentary basin in a series of Permian evaporites at a depth of approx. 240 to approx. 520 m below sea level and the total thickness about 280 m. This series includes fine-crystalline salt to coarse-crystalline salt, but the whole salt series is heavily contaminated with consolidated clay minerals locally called argillite and also iron hydroxides, which will significantly affect the efficient exploitation of this deposit in the future. Salts from the Sorkol deposit have completely different features than the salts from European (Permian) deposits described so far in Polish literature.