Vermikulit s Ag a Cu použitý jako antibakteriální nanoplnivo v polyethylenu

Vermiculite (Ver) enriched with silver and copper was used as nanofiller to the polyethylene (PE) matrix. Specifically, the low density polyethylene (LDPE) was chosen as a matrix. The samples Ver-Ag,Cu were prepared by shaking of Ver with the aqueous solutions of silver and copper nitrate. The mixtures of the Ver nanofillers and PE were homogenized by melt compounding technique and further thin plates were pressed from stiff matter of PE with Ver nanofiller. The exfoliation of the powdery Ver nanofillers in PE matrix was characterized by the X-ray diffraction analysis of thin plates. Distribution of Ver nanofiller in PE matrix was observed by Light microscopy. The reinforcing effect of nanofillers onto PE matrix was studied by creep experiment. Antibacterial activity of powder Ver-Ag,Cu samples and surfaces of PE/Ver-Ag,Cu samples was tested on the Gram-positive bacteria Enterococcus faecalis. All tested PE/Ver-Ag,Cu surfaces showed good antibacterial behaviour after 24 h in comparison to pure PE. The number of colonies decreased from the countless number to several hundred colonies.Vermikulit (Ver) obohacený stříbrem a mědí byl použit jako nanoplnivo v polyethylenové (PE) matrici. Konkrétně byl jako matrice vybrán nízko hustotní polyethylen (LDPE). Vzorky Ver-Ag,Cu byly připraveny mícháním Ver s vodnými roztoky dusičnanu stříbrného a měďnatého. Směsi Ver nanoplniv a PE byly homogenizovány postupem míchání taveniny a následně byly ze ztuhnuté směsi PE s Ver nanoplnivem vylisovány tenké destičky. Exfoliace práškového Ver nanoplniva v PE matrici byla hodnocena pomocí Rentgenové difrakční analýzy tenkých destiček. Distribuce Ver nanoplniva v PE matrici byla studována Světelnou mikroskopií. Vyztužující efekt nanoplniv na PE matrici byl studován pomocí krípového experimentu. Antibakteriální působení práškových vzorků Ver-Ag,Cu a povrchů vzorků PE/Ver-Ag,Cu bylo testováno na grampozitivní bakterii Enterococcus faecalis. Všechny testované povrchy PE/Ver-Ag,Cu vykazovaly dobré antibakteriální působení po 24 h oproti povrchu čistého PE. Počet kolonií poklesl z nespočetného množství na několik stovek kolonií

Silver and/or copper vermiculites and their antibacterial effect

Vermiculite (V) from Brazil with aqueous solutions AgNO3 and/or Cu(NO3)2 was used for preparation of nanocomposites V/Ag, V/Cu, V/AgCu and V/CuAg using two procedures and their effect on bacteria was compared. Structural changes were evaluated using X-ray diffraction (XRD) analysis, Infrared spectroscopy (IRS) and Scanning electron microscopy (SEM). Elemental chemical composition was determined using X-ray fluorescence (XRF) analysis and the solutions were analyzed by Atomic emission spectroscopy with inductively coupled plasma (AES-ICP). Antibacterial properties of Ag- and Cu-vermiculites and combined Ag/Cu-vermiculites were tested on two bacteria groups: (1) Gram-positive, G+, (Staphylococcus aureus and Enterococcus faecalis) and (2) Gram-negative, G-, (Pseudomonas aeruginosa and Klebsiella pneumoniae). The samples under antibacterial testing showed different effective times and minimum inhibitory concentration (MIC) values. The Gram-negative bacteria showed higher sensitivity to the prepared samples than Gram-positive bacteria. The combined Cu/Ag vermiculites stopped the bacterial growth at lower MIC value.Web of Science1011049

Carmellose mucoadhesive oral films containing vermiculite/chlorhexidine nanocomposites as innovative biomaterials for treatment of oral infections

Infectious stomatitis represents the most common oral cavity ailments. Current therapy is insufficiently effective because of the short residence time of topical liquid or semisolid medical formulations. An innovative application form based on bioadhesive polymers featuring prolonged residence time on the oral mucosa may be a solution to this challenge. This formulation consists of a mucoadhesive oral film with incorporated nanocomposite biomaterial that is able to release the drug directly at the target area. This study describes the unique approach of preparing mucoadhesive oral films from carmellose with incorporating a nanotechnologically modified clay mineral intercalated with chlorhexidine. The multivariate data analysis was employed to evaluate the influence of the formulation and process variables on the properties of the medical preparation. This evaluation was complemented by testing the antimicrobial and antimycotic activity of prepared films with the aim of finding the most suitable composition for clinical application. Generally, the best results were obtained with sample containing 20 mg of chlorhexidine diacetate carried by vermiculite, with carmellose in the form of nonwoven textile in its structure. In addition to its promising physicomechanical, chemical, and mucoadhesive properties, the formulation inhibited the growth of Staphylococcus and Candida; the effect was prolonged for tens of hours.Web of Scienceart. no. 58014

Study of the Structure and Antimicrobial Activity of Ca-Deficient Ceramics on Chlorhexidine Nanoclay Substrate

Novel biomedical composites, based on organically modified vermiculite and montmorillonite with deposited Ca-deficient hydroxyapatite (CDH), were prepared. The monoionic sodium forms of vermiculite and montmorillonite were intercalated with chlorhexidine diacetate (CA). The surfaces of organoclays were used for the precipitation of Ca-deficient hydroxyapatite. The composites with Ca-deficient hydroxyapatite showed very good antibacterial effects, similar to the antimicrobial activity of pure organoclay samples. Better antibacterial activity was shown in the organically modified montmorillonite sample with Ca-deficient hydroxyapatite compared with the vermiculite composite, but, in the case of Staphylococcus aureus, both composites showed the same minimum inhibitory concentration (MIC) value. The antimicrobial effect of composites against bacteria and fungi increased with the time of exposure. The structural characterization of all the prepared materials, performed using X-ray diffraction and FT infrared spectroscopy analysis, detected no changes in the original clay or CDH during the intercalation or precipitation process, therefore we expect the strength of the compounds to be in the original power.Web of Science1218art. no. 299

Vermiculite With Ag and Cu Used as an Antibacterial Nanofiller in Polyethylene/ Vermikulit S Ag A Cu Použitý Jako Antibakteriální Nanoplnivo V Polyethylenu

Vermikulit (Ver) obohacený stříbrem a mědí byl použit jako nanoplnivo v polyethylenové (PE) matrici. Konkrétně byl jako matrice vybrán nízko hustotní polyethylen (LDPE). Vzorky Ver-Ag,Cu byly připraveny mícháním Ver s vodnými roztoky dusičnanu stříbrného a měďnatého. Směsi Ver nanoplniv a PE byly homogenizovány postupem míchání taveniny a následně byly ze ztuhnuté směsi PE s Ver nanoplnivem vylisovány tenké destičky. Exfoliace práškového Ver nanoplniva v PE matrici byla hodnocena pomocí Rentgenové difrakční analýzy tenkých destiček. Distribuce Ver nanoplniva v PE matrici byla studována Světelnou mikroskopií. Vyztužující efekt nanoplniv na PE matrici byl studován pomocí krípového experimentu. Antibakteriální působení práškových vzorků Ver-Ag,Cu a povrchů vzorků PE/Ver-Ag,Cu bylo testováno na grampozitivní bakterii Enterococcus faecalis. Všechny testované povrchy PE/Ver-Ag,Cu vykazovaly dobré antibakteriální působení po 24 h oproti povrchu čistého PE. Počet kolonií poklesl z nespočetného množství na několik stovek kolonií

Antibacterial activity of organomontmorillonites and organovermiculites prepared using chlorhexidine diacetate

Organoclays with antibacterial activity were prepared from cation exchanged Ag+, Cu2 + and Zn2 + forms of montmorillonite and vermiculite using five concentrations of chlorhexidine diacetate. The samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The antibacterial activity against Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding the minimum inhibitory concentration (MIC). All prepared organomontmorillonites and organovermiculites showed the best antibacterial activity against an E. coli bacterial strain.Web of Science83-84231

Antibacterial polyethylene/clay nanocomposites using chlorhexidine as organic modifier

The set of low density polyethylene/clay nanocomposites with increasing amount of organoclay nanofiller (3, 6 and 10 wt %) was prepared by melt compounding procedure without additives. An antimicrobial drug, chlorhexidine diacetate (CA), was loaded into Zn2+ form of clay mineral vermiculite (ZnVer) at very low concentration and then organoclay nanofiller CA/ZnVer was incorporated into polymeric matrix. The structural characteristics of all prepared samples were studied by XRD and FTIR techniques. The nanocomposites were tested for antibacterial activity against Staphylococcus aureus and Escherichia coli. Prepared samples showed a very good antibacterial activity with long lasting effect against S. aureus and slightly worse effect against E. coli.Web of Science2125224

Polyethylene/organo-inorgano vermiculites and their antimicrobial properties

Clay mineral vermiculite was treated with silver and copper nitrate solutions and samples were subsequently modified with organic compound (dodecylamine) via solid-solid melt intercalation. Prepared organo-inorgano vermiculites were used as nanofillers to the polyethylene matrix. Mixtures of polyethylene with vermiculite nanofillers, prepared by melt compounding technique, were pressed into thin plates. Structure changes of prepared powder vermiculite nanofillers and polyethylene/vermiculite composites were studied by X-ray diffraction analysis. The X-ray diffraction patterns of vermiculite nanofillers confirm intercalation of dodecylamine into the vermiculite interlayer. Antimicrobial properties of powder vermiculite nanofillers were evaluated by the minimum inhibitory concentration of samples which is needed to completely stop the bacterial growth and polyethylene/vermiculite composites were evaluated by the number of colony forming units survived on surfaces of composite plates. Different bacterial strains were studied: (1) Gram-positive, represented by bacteria Staphylococcus aureus and Enterococcus faecalis, (2) Gram-negative, represented by bacteria Escherichia coli and Pseudomonas aeruginosa, and (3) yeast, Candida albicans. Powder vermiculite nanofillers and surfaces of polyethylene/vermiculite composites showed good antimicrobial effect against tested bacteria and yeast. Powder vermiculite nanofillers show antimicrobial effect already after 30 minutes of tested time. Composite plates exhibited decrease of colony forming units number about 5-7 logarithmic orders depending on bacteria after 24 hours of tested time.Web of Science1952605259

Preparation and some properties of polyethylene/vermiculite nanocomposites

The high aspect ratio of layered silicate nanoparticles is very convenient to modify the properties of the polymer, but the hydrophilic nature of silicate surfaces impedes their homogeneous dispersion in the organic polymer phase. The hydrophilic clay minerals are commonly treated with ammonium cations with long alkyl chains to improve the compatibility between the silicate layers and the polymer matrix. In this study, clay mineral vermiculite (V) was used as a clay nanofiller to the polyethylene (PE) and the functional and mechanical properties of PE/V nanocomposite plates were characterized. Vermiculite has been modified to the role of nanofiller with organic dodecylamine (DA) compounds in various concentrations. Exfoliation of modified vermiculite nanofiller in PE was studied on the nanocomposite plates using X-ray diffraction analysis. The quality of nanofiller distribution in polymer matrix was observed using light microscopy. Changes in mechanical properties of the PE/VDA nanocomposites in comparison with the pure PE were studied on the data from the Creep measurements. The antibacterial activity of the surfaces of composite plates was tested on the Gram-positive bacteria Enterococcus faecalis

Preparation of novel organovermiculites with antibacterial activity using chlorhexidine diacetate

The novel antibacterial organovermiculites with different mass ratios of chlorhexidine diacetate (CA) were successfully prepared by ion exchange reactions. The resultant organovermiculites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal properties of prepared organovermiculites were investigated by simultaneous thermogravimetry (TG) and differential thermal analysis (DTA). The antibacterial activity of prepared organovermiculites against Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding minimum inhibitory concentration (MIC). Antibacterial studies showed that the organovermiculites strongly inhibited the growth of variety of microorganisms