Polyelectrolytic multilayers (PEMs) with enhanced antibacterial properties were built up onto commercial poly(ethylene terephthalate) (PET) films based on the layer by layer assembling of bacterial contact killing chitosan and bacterial repelling highly hydrated hyaluronic acid. The optimization of the aminolysis modification reaction of PET was carried out by the study of the mechanical properties and the surface characterization of the modified polymers. The layer by layer assembly was successfully monitored by TEM microscopy, surface zeta-potential, contact angle measurements and, after labeling with fluorescein isothiocyanate (FTIC) by absorption spectroscopy and confocal fluorescent microscopy. Beside, the stability of the PEMs was studied at physiological conditions in absence and in the presence of lysozyme and hyaluronidase enzymes. Antibacterial properties of the obtained PEMs against Escherichia coli were compared with original commercial PET.

• Klíčová slova
• Chitosan, Hyaluronic acid, Poly(ethylene terephthalate) aminolysis, Polyelectrolyte multilayers,
• MeSH
• antibakteriální látky chemie   farmakologie   MeSH
• biokompatibilní potahované materiály chemie   farmakologie   MeSH
• chitosan analogy a deriváty   chemie   farmakologie   MeSH
• Escherichia coli účinky léků   MeSH
• fluorescein-5-isothiokyanát chemie   MeSH
• hyaluronoglukosaminidasa chemie   MeSH
• kyselina hyaluronová analogy a deriváty   chemie   farmakologie   MeSH
• muramidasa chemie   MeSH
• polyethylentereftaláty chemie   farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antibakteriální látky MeSH
• biokompatibilní potahované materiály MeSH
• chitosan MeSH
• fluorescein-5-isothiokyanát MeSH
• hyaluronoglukosaminidasa MeSH
• kyselina hyaluronová MeSH
• muramidasa MeSH
• polyethylentereftaláty MeSH

In this study, fibrous membranes from recycled-poly(ethylene terephthalate)/silk fibroin (r-PSF) were prepared by electrospinning for filtration applications. The effect of silk fibroin on morphology, fibers diameters, pores size, wettability, chemical structure, thermo-mechanical properties, filtration efficiency, filtration performance, and comfort properties such as air and water vapor permeability was investigated. The filtration efficiency (FE) and quality factor (Qf), which represents filtration performance, were calculated from penetration through the membranes using aerosol particles ranging from 120 nm to 2.46 μm. The fiber diameter influenced both FE and Qf. However, the basis weight of the membranes has an effect, especially on the FE. The prepared membranes were classified according to EN149, and the most effective was assigned to the class FFP1 and according to EN1822 to the class H13. The impact of silk fibroin on the air permeability was assessed. Furthermore, the antibacterial activity against bacteria S. aureus and E. coli and biocompatibility were evaluated. It is discussed that antibacterial activity depends not only on the type of used materials but also on fibrous membranes' surface wettability. In vitro biocompatibility of the selected samples was studied, and it was proven to be of the non-cytotoxic effect of the keratinocytes (HaCaT) after 48 h of incubation.

• Klíčová slova
• air filtration, antibacterial activity, comfort properties, electrospun membrane, poly(ethylene terephthalate), silk fibroin,
• Publikační typ
• časopisecké články MeSH

Methods for analysis of microplastic in soils are still being developed. In this study, we evaluated the potential of a soil universal model method (SUMM) based on thermogravimetry (TGA) for the identification and quantification of microplastics in standard loamy sand. Blank and spiked soils (with amounts of one of four microplastic types) were analyzed by TGA. For each sample, thermal mass losses (TML) in 10 °C intervals were extracted and used for further analysis. To explain and demonstrate the principles of SUMM, two scenarios were discussed. The first refers to a rare situation in which an uncontaminated blank of investigated soil is available and TML of spiked and blank soils are subtracted. The results showed that the investigated microplastics degraded in characteristic temperature areas and differences between spiked and blank soils were proportional to the microplastics concentrations. The second scenario reflects the more common situation where the blank is not available and needs to be replaced by the previously developed interrelationships representing soil universal models. The models were consequently subtracted from measured TML. Sparse principal component analysis (sPCA) identified 8 of 14 modeled differences between measured TMLs and the universal model as meaningful for microplastics discrimination. Calibrating various microplastics concentrations with the first principal component extracted from sPCA resulted in linear fits and limits of detection in between environmentally relevant microplastics concentrations. Even if such an approach using calculated standards still has limitations, the SUMM shows a certain potential for a fast pre-screening method for analysis of microplastics in soils.

• Klíčová slova
• Mass loss on ignition, Microplastics, Modelling, Soil universal model method, Thermogravimetry,
• MeSH
• analýza hlavních komponent MeSH
• chemické modely * MeSH
• látky znečišťující půdu analýza   MeSH
• plastické hmoty analýza   chemie   MeSH
• polyethylen analýza   MeSH
• polyethylentereftaláty analýza   MeSH
• polystyreny analýza   MeSH
• polyvinylchlorid analýza   MeSH
• půda chemie   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• látky znečišťující půdu MeSH
• plastické hmoty MeSH
• polyethylen MeSH
• polyethylentereftaláty MeSH
• polystyreny MeSH
• polyvinylchlorid MeSH
• půda MeSH

Adverse effects of microplastics on soil abiotic properties have been attributed to changes in the soil structure. Notably, however, the effects on the supramolecular structure of soil organic matter (SOM) have been overlooked, despite their key role in most soil properties. This work accordingly investigated the influence of plastic residues at various concentrations on the SOM supramolecular structure and soil water properties. To model plastic residues of micro-bioplastics, spherical or spherical-like poly-3-hydroxybutyrate (PHB) was used, while polyethylene terephthalate (PET) was used as a model of conventional microplastics. The results suggest that both types of plastic residues affect SOM properties, including physical stability (represented by water molecule bridges), water binding (represented by decreased desorption enthalpy or faster desorption), and the stability of SOM aliphatic crystallites. The results further showed that the polyester-based microplastics and micro-bioplastics affected the SOM abiotic characteristics and that therefore the observed effects cannot be attributed solely to changes in the whole soil structure. Notably, similar adverse effects on SOM were observed for both tested plastic residues, although the effect of PHB was less pronounced compared to that of PET.

• Klíčová slova
• DSC, PET microplastics, PHB micro-bioplastics, soil, water,
• MeSH
• hydroxybutyráty MeSH
• mikroplasty * MeSH
• plastické hmoty MeSH
• polyestery MeSH
• polyethylentereftaláty MeSH
• půda * chemie   MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hydroxybutyráty MeSH
• mikroplasty * MeSH
• plastické hmoty MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery MeSH
• polyethylentereftaláty MeSH
• půda * MeSH
• voda MeSH

In the last two decades, the importance of nanomaterials in modern technologies has been unquestionable. Metal nanoparticles are frequently used in many areas of science and technology, delivering unprecedented improvements to properties of the conventional materials. This work introduces an effective tool for preparing a highly enriched poly (ethylene terephthalate) (PET) surface with silver nanoparticles, firmly immobilized in the same surface area on polymer. We showed that besides pristine polymer, this approach may be successfully applied also on laser pre-treated PET with laser-induced periodic surface structures. At the same time, its final nanostructure may be effectively controlled by laser fluence applied during the immobilization process.

• Klíčová slova
• laser processing, polyethyleneterephthalate, ripple structures, silver nanoparticles, surface morphology,
• Publikační typ
• časopisecké články MeSH

The use of plastic materials in daily life, industry, and agriculture can cause soil pollution with plastic fragments down to the micrometer scale, i.e., microplastics. Quantitative assessment of microplastics in soil has been limited so far. Until now, microplastic analyses in soil require laborious sample cleanup and are mostly restricted to qualitative assessments. In this study, we applied thermogravimetry-mass spectrometry (TGA-MS) to develop a method for the direct quantitative analysis of poly(ethylene terephthalate) (PET) without further sample pretreatment. For this, soil samples containing 1.61 ± 0.15 wt % organic matter were spiked with 0.23-4.59 wt % PET bottle recyclate microplastics. dl-Cysteine was used as the internal standard (IS). Sample mixtures were pyrolyzed with a 5 K min-1 ramp (40-1000 °C), while sample mass loss and MS signal intensity of typical PET pyrolysis products were recorded. We found MS signal intensities linearly responding to microplastic concentrations. The most-promising results were obtained with the IS-corrected PET pyrolysis product vinylbenzene/benzoic acid ( m/ z = 105, adj. R2 = 0.987). The limits of detection and quantification were 0.07 and 1.72 wt % PET, respectively. Our results suggest that TGA-MS can be an easy and viable complement to existing methods such as pyrolysis or thermogravimetry-thermal desorption assays followed by gas chromatography/mass spectrometry detection or to spectral microscopy techniques.

• Publikační typ
• časopisecké články MeSH

The massive increase in the use of PET plastic bottles has raised the challenge of accumulated waste plastics disposal and its related environmental concerns. Reusing this plastic waste through a solvent-based recycling process seems to be an eco-friendly solution for eliminating waste plastic and converting them into high quality products. The selection of solvent with its temperature requirement for the dissolution of polymeric materials is crucial in the solvent-based recycling process. Therefore, an innovative MATLAB program named HSPs-TPT was designed and constructed in this work to evaluate the dissolving power of solvents. Through this program, the solubility of the waste PET polymer was examined in thirteen (13) different solvents at different temperatures. As a results, the degree of waste PET polymer dissolution in the solvents was presented as the polymer-solvent solubility diagram, which provided the information about the relative energy difference (RED) change with the temperature rise. The program also provided the temperature range effective for the dissolution of PET by indicating the minimum and maximum solubility point for each solvent, which was further validated by the experimental data found in the literature. The proposed MATLAB program can numerically analyse the solubility of a polymer in different solvents in a short time for the recycling process and fabrication of different value-added plastic products such as polymer monoliths and membrane filters.

• Klíčová slova
• Hansen solubility, Membrane, Model analysis, Polyethylene terephthalate (PET), Waste,
• MeSH
• plastické hmoty * MeSH
• polyethylentereftaláty * MeSH
• recyklace MeSH
• rozpouštědla MeSH
• rozpustnost MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• plastické hmoty * MeSH
• polyethylentereftaláty * MeSH
• rozpouštědla MeSH

The effect of aqueous solutions of selected ionic liquids solutions on Ideonella sakaiensis PETase with bis(2-hydroxyethyl) terephthalate (BHET) substrate were studied by means of molecular dynamics simulations in order to identify the possible effect of ionic liquids on the structure and dynamics of enzymatic Polyethylene terephthalate (PET) hydrolysis. The use of specific ionic liquids can potentially enhance the enzymatic hydrolyses of PET where these ionic liquids are known to partially dissolve PET. The aqueous solution of cholinium phosphate were found to have the smallest effect of the structure of PETase, and its interaction with (BHET) as substrate was comparable to that with the pure water. Thus, the cholinium phosphate was identified as possible candidate as ionic liquid co-solvent to study the enzymatic hydrolyses of PET.

• Klíčová slova
• BHET, PET, PETase, ionic liquids (ILs), molecular dynamics (MD) simulations,
• MeSH
• Burkholderiales enzymologie   MeSH
• hydrofobní a hydrofilní interakce MeSH
• hydrolasy metabolismus   MeSH
• hydrolýza MeSH
• iontové kapaliny chemie   MeSH
• konformace proteinů MeSH
• kyseliny ftalové chemie   MeSH
• polyethylentereftaláty chemie   MeSH
• rozpouštědla chemie   MeSH
• simulace molekulární dynamiky MeSH
• vodíková vazba MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydrolasy MeSH
• iontové kapaliny MeSH
• kyseliny ftalové MeSH
• polyethylentereftaláty MeSH
• rozpouštědla MeSH
• terephthalic acid MeSH Prohlížeč

Mineral bottled water packed in three polymers viz., virgin polyethylene terephthalate (PET), recycled PET, and low-density polyethylene (LDPE) were investigated for the occurrence, migration, and health risk of phthalic acid esters (PAEs) at 25 °C, 35 °C, and 45 °C. The average concentration of six USEPA priority PAEs in refrigerated water samples was highest in recycled PET> LDPE > virgin PET. The highest leaching was seen at 45 °C after 2 days for LDPE water packets with ∑6PAEs amounting to 64,300 ng/L. Similarly, for recycled PET, the highest migration was seen at 45 °C after seven days (3,800 µg/L). Bis 2-ethyl hexyl phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the predominant plasticizers from PET bottles and LDPE water packets, respectively. Predicted concentration after three weeks based on best fit obtained through the polynomial model for PET bottles was seen higher than the recommended limit suggested by USEPA (6 µg/L) and WHO (8 µg/L).

• Klíčová slova
• LDPE, Migration, Mineral bottled water, PET, Plasticizers,
• MeSH
• pitná voda * analýza   MeSH
• polyethylen MeSH
• polyethylentereftaláty MeSH
• změkčovadla * analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• phthalic acid MeSH Prohlížeč
• pitná voda * MeSH
• polyethylen MeSH
• polyethylentereftaláty MeSH
• změkčovadla * MeSH

Composites of multiwalled carbon nanotubes with poly(ethylene terephthalate) (PET-MWCNT) with up to 3 vol% MWCNTs were prepared and characterized by broad-band AC conductivity and dielectric spectroscopy up to the infrared range using several techniques. A very low electrical percolation threshold of 0.07 vol% MWCNTs was revealed from the low-frequency conductivity plateau as well as from DC conductivity, whose values show the same critical power dependence on MWCNT concentration with the exponent t = 4.3. Above the plateau, the AC conductivity increases with frequency up to the THz range, where it becomes overlapped with the absorption of vibrational modes. The temperature dependence down to ~5 K has shown semiconductor behaviour with a concentration-independent but weakly temperature-dependent small activation energy of ~3 meV. The behaviour is compatible with the previously suggested fluctuation-induced tunnelling conductivity model through a thin (~1 nm) polymer contact layer among the adjacent MWCNTs within percolated clusters. At higher frequencies, deviations from the simple universal conductivity behaviour are observed, indicating some distribution of energy barriers for an electron hopping mechanism.

• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH