The polymeric cytisine-enriched fibers based on poly(3-hydroxybutyrate) were obtained using electrospinning method. The biocompatibility study, advanced thermal analysis and release of cytisine from the poly(3-hydroxybutyrate) fibers were carried out. The nanofibers' morphology was evaluated by scanning electron microscopy. The formation and description of phases during the thermal processes of fibers by the advanced thermal analysis were examined. The new quantitative thermal analysis of polymeric fibers with cytisine phases based on vibrational, solid and liquid heat capacities was presented. The apparent heat capacity of fibers was measured using the standard differential scanning calorimetry. The quantitative analysis allowed for the study of the glass transition and melting/crystallization process. The mobile amorphous fraction, degree of crystallinity and rigid amorphous fraction were determined depending on the thermal history of semicrystalline polymeric fibers. Furthermore, the cytisine dissolution behaviour was studied. It was observed that the kinetic of the release from polymeric nanofiber is delayed than for the marketed product. The immunosafety of the tested polymeric nanofibers with cytisine was confirmed by the Food and Drug Agency Guidance as well as the European Medicines Agency. The polymeric matrix with cytisine seems to be a promising candidate for the prolonged release formulation.

• Klíčová slova
• Cytisine, Differential scanning calorimetry, Electrospinning, Poly(3-hydroxybutyrate),
• MeSH
• diferenciální skenovací kalorimetrie MeSH
• kyselina 3-hydroxymáselná MeSH
• léky s prodlouženým účinkem chemie   MeSH
• nanovlákna * chemie   MeSH
• polymery * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cytisine MeSH Prohlížeč
• kyselina 3-hydroxymáselná MeSH
• léky s prodlouženým účinkem MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polymery * MeSH

Fused deposition modelling (FDM) is a process of additive manufacturing allowing creating of highly precise complex three-dimensional objects for a large range of applications. The principle of FDM is an extrusion of the molten filament and gradual deposition of layers and their solidification. Potential applications in pharmaceutical and medical fields require the development of biodegradable and biocompatible thermoplastics for the processing of filaments. In this work, the potential of production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) filaments for FDM was investigated in respect to its thermal stability. Copolymer P(3HB-co-4HB) was biosynthesised by Cupriavidus malaysiensis. Rheological and mechanical properties of the copolymer were modified by the addition of plasticizers or blending with poly(lactic acid). Thermal stability of mixtures was studied employing thermogravimetric analysis and rheological analyses by monitoring the time-dependent changes in the complex viscosity of melt samples. The plasticization of P(3HB-co-4HB) slightly hindered its thermal degradation but the best stabilization effect was found in case of the copolymer blended with poly(lactic acid). Overall, rheological, thermal and mechanical properties demonstrated that the plasticized P(3HB-co-4HB) is a potential candidate of biodegradable polymer for FDM processes.

• Klíčová slova
• 3D printing, Cupriavidus malaysiensis, Fused deposition modelling, Poly(3-hydroxybutyrate-co-4-hydroxybutyrate), Poly(lactic acid), Rheological properties,
• MeSH
• Cupriavidus metabolismus   MeSH
• hydroxybutyráty chemie   MeSH
• molekulární struktura MeSH
• molekulová hmotnost MeSH
• polyestery chemie   MeSH
• reologie MeSH
• teplota MeSH
• změkčovadla chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydroxybutyráty MeSH
• poly(3-hydroxybutyrate-co-4-hydroxybutyrate) MeSH Prohlížeč
• poly(lactide) MeSH Prohlížeč
• polyestery MeSH
• změkčovadla MeSH

Poly(3-hydroxybutyrate) (PHB) is a common carbon- and energy-storage compound simultaneously produced and degraded into its monomer 3-hydroxybutyrate (3HB) by numerous bacteria and Archae in a metabolic pathway called the PHB cycle. We investigated 3HB as a chemical chaperone capable of protecting model enzymes, namely lipase and lysozyme, from adverse effects of high temperature and oxidation. Heat-mediated denaturation of lipase in the presence or absence of 3HB was monitored by dynamic light scattering (DLS) revealing a significant protective effect of 3HB which increased as its concentration rose. Furthermore, when compared at the same molar concentration, 3HB showed a greater protective effect than the well-known chemical chaperones trehalose and hydroxyectoine. The higher protective effect of 3HB was also confirmed when employing differential scanning calorimetry (DSC) and lysozyme as a model enzyme. Furthermore, 3HB was capable of protecting lipase not only against thermal-mediated denaturation but also against oxidative damage by Cu(2+) and H2O2; its protection was higher than that of trehalose and comparable to that of hydroxyectoine. Taking into account that the PHB-producing strain Cupriavidus necator H16 reveals a 16.5-fold higher intracellular concentration than the PHB non-producing mutant C. necator PHB(-4), it might be expected that the functional PHB cycle might be responsible for maintaining a higher intracellular level of 3HB which, aside from other positive aspects of functional PHB metabolism, enhances stress resistance of bacterial strains capable of simultaneous PHB synthesis and mobilization. In addition, 3HB can be used in various applications and formulations as an efficient enzyme-stabilizing and enzyme-protecting additive.

• Klíčová slova
• 3-Hydroxybutyrate, Chemical chaperone, Compatible solutes, PHB, PHB cycle, Poly(3-hydroxybutyrate),
• MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• Cupriavidus necator chemie   enzymologie   metabolismus   MeSH
• hydroxybutyráty metabolismus   MeSH
• kyselina 3-hydroxymáselná chemie   metabolismus   MeSH
• muramidasa chemie   metabolismus   MeSH
• ochranné látky chemie   metabolismus   MeSH
• oxidace-redukce MeSH
• oxidační stres MeSH
• polyestery metabolismus   MeSH
• stabilita enzymů MeSH
• vysoká teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• hydroxybutyráty MeSH
• kyselina 3-hydroxymáselná MeSH
• muramidasa MeSH
• ochranné látky MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery MeSH

This work explores molecular, morphological as well as biotechnological features of the highly promising polyhydroxyalkanoates (PHA) producer Halomonas halophila. Unlike many other halophiles, this bacterium does not require expensive complex media components and it is capable to accumulate high intracellular poly(3-hydroxybutyrate) (PHB) fractions up to 82% of cell dry mass. Most remarkably, regulating the concentration of NaCl apart from PHB yields influences also the polymer's molecular mass and polydispersity. The bacterium metabolizes various carbohydrates including sugars predominant in lignocelluloses and other inexpensive substrates. Therefore, the bacterium was employed for PHB production on hydrolysates of cheese whey, spent coffee grounds, sawdust and corn stover, which were hydrolyzed by HCl; required salinity of cultivation media was set up during neutralization by NaOH. The bacterium was capable to use all the tested hydrolysates as well as sugar beet molasses for PHB biosynthesis, indicating its potential for industrial PHB production.

• Klíčová slova
• Halomonas halophila, Halophiles, Lignocellulose hydrolysates, Morphology of bacterial cells, Polyhydroxyalkanoates,
• MeSH
• Halomonas * MeSH
• hydroxybutyráty * MeSH
• kyselina 3-hydroxymáselná MeSH
• polyestery * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydroxybutyráty * MeSH
• kyselina 3-hydroxymáselná MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery * MeSH

The aim of this work was to develop a soap-based method for the isolation of poly(3-hydroxybutyrate) from bacterial biomass. The method consisted of adding soap derived from waste cooking oil to a concentrated (25%) biomass suspension, heating and centrifugal separation. Purity above 95% could be achieved with soap:cell dry mass ratios at least 0.125 g/g, making the method comparable to other surfactant-based protocols. Molecular weights Mw of products from all experiments were between 350 and 450 kDa, being high enough for future material applications. Addition of hydrochloric acid to the wastewater led to the precipitation of soap and part of non-P3HB cell mass. The resulting precipitate was utilized as a carbon source in biomass production and increased substrate-to-P3HB conversion.

• Klíčová slova
• Downstream process, Isolation, P3HB, PHA, Recovery,
• MeSH
• biomasa MeSH
• bioreaktory * MeSH
• hydroxybutyráty MeSH
• kyselina 3-hydroxymáselná MeSH
• mýdla * MeSH
• polyestery MeSH
• vaření MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydroxybutyráty MeSH
• kyselina 3-hydroxymáselná MeSH
• mýdla * MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery MeSH

The search for eco-friendly substitutes for traditional plastics has led to the production of biodegradable bioplastics. However, concerns have been raised about the impact of bioplastic biodegradation on soil health. Despite these concerns, the potential negative consequences of bioplastics during various stages of biodegradation remain underexplored. Therefore, this study aims to investigate the impact of micro-bioplastics made of poly-3-hydroxybutyrate (P3HB) on the properties of three different soils. In our ten-month experiment, we investigated the impact of poly-3-hydroxybutyrate (P3HB) on Chernozem, Cambisol, and Phaeozem soils. Our study focused on changes in soil organic matter (SOM), microbial activity, and the level of soil carbon and nitrogen. The observed changes indicated an excessive level of biodegradation of SOM after the soils were enriched with micro-particles of P3HB, with concentrations ranging from 0.1% to 3%. The thermogravimetric analysis confirmed the presence of residual P3HB (particularly in the 3% treatment) and underscored the heightened biodegradation of SOM, especially in the more stable SOM fractions. This was notably evident in Phaeozem soils, where even the stable SOM pool was affected. Elemental analysis revealed changes in soil organic carbon content following P3HB degradation, although nitrogen levels remained constant. Enzymatic activity was found to vary with soil type and responded differently across P3HB concentration levels. Our findings confirmed that P3HB acts as a bioavailable carbon source. Its biodegradation stimulates the production of enzymes, which in turn affects various soil elements, indicating complex interactions within the soil ecosystem.

• MeSH
• biopolymery MeSH
• dusík analýza   MeSH
• ekosystém * MeSH
• hydroxybutyráty MeSH
• polyestery MeSH
• polyhydroxybutyráty * MeSH
• půda * MeSH
• uhlík analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biopolymery MeSH
• dusík MeSH
• hydroxybutyráty MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery MeSH
• polyhydroxybutyráty * MeSH
• půda * MeSH
• uhlík MeSH

This work presents a comprehensive analysis of the biodegradation of polyhydroxybutyrate (PHB) and chemically modified PHB with different chemical and crystal structures in a soil environment. A polymer modification reaction was performed during preparation of the chemically modified PHB films, utilizing 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane as a free-radical initiator and maleic anhydride. Films of neat PHB and chemically modified PHB were prepared by extrusion and thermocompression. The biological agent employed was natural mixed microflora in the form of garden soil. The course and extent of biodegradation of the films was investigated by applying various techniques, as follows: a respirometry test to determine the production of carbon dioxide through microbial degradation; scanning electron microscopy (SEM); optical microscopy; fluorescence microscopy; differential scanning calorimetry (DSC); and X-ray diffraction (XRD). Next-generation sequencing was carried out to study the microbial community involved in biodegradation of the films. Findings from the respirometry test indicated that biodegradation of the extruded and chemically modified PHB followed a multistage (2-3) course, which varied according to the spatial distribution of amorphous and crystalline regions and their spherulitic morphology. SEM and polarized optical microscopy (POM) confirmed that the rate of biodegradation depended on the availability of the amorphous phase in the interspherulitic region and the width of the interlamellar region in the first stage, while dependence on the size of spherulites and thickness of spherulitic lamellae was evident in the second stage. X-ray diffraction revealed that orthorhombic α-form crystals with helical chain conformation degraded concurrently with β-form crystals with planar zigzag conformation. The nucleation of PHB crystals after 90 days of biodegradation was identified by DSC and POM, a phenomenon which impeded biodegradation. Fluorescence microscopy evidenced that the crystal structure of PHB affected the physiological behavior of soil microorganisms in contact with the surfaces of the films.

• MeSH
• hydroxybutyráty * chemie   MeSH
• kyselina 3-hydroxymáselná MeSH
• polyestery * chemie   MeSH
• půda MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hydroxybutyráty * MeSH
• kyselina 3-hydroxymáselná MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery * MeSH
• polyhydroxybutyrate MeSH Prohlížeč
• půda MeSH

The physical properties and non-isothermal melt- and cold-crystallisation kinetics of poly (l-lactic acid) (PLLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biobased polymers reprocessed by mechanical milling of moulded specimens and followed injection moulding with up to seven recycling cycles are investigated. Non-isothermal crystallisation kinetics are evaluated by the half-time of crystallisation and a procedure based on the mathematical treatment of DSC cumulative crystallisation curves at their inflection point (Kratochvil-Kelnar method). Thermomechanical recycling of PLLA raised structural changes that resulted in an increase in melt flow properties by up to six times, a decrease in the thermal stability by up to 80 °C, a reduction in the melt half-time crystallisation by up to about 40%, an increase in the melt crystallisation start temperature, and an increase in the maximum melt crystallisation rate (up to 2.7 times). Furthermore, reprocessing after the first recycling cycle caused the elimination of cold crystallisation when cooling at a slow rate. These structural changes also lowered the cold crystallisation temperature without impacting the maximum cold crystallisation rate. The structural changes of reprocessed PHBV had no significant effect on the non-isothermal crystallisation kinetics of this material. Additionally, the thermomechanical behaviour of reprocessed PHBV indicates that the technological waste of this biopolymer is suitable for recycling as a reusable additive to the virgin polymer matrix. In the case of reprocessed PLLA, on the other hand, a significant decrease in tensile and flexural strength (by 22% and 46%, respectively) was detected, which reflected changes within the biobased polymer structure. Apart from the elastic modulus, all the other thermomechanical properties of PLLA dropped down with an increasing level of recycling.

• Klíčová slova
• mechanical recycling, non-isothermal crystallisation kinetics, poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (l-lactic acid),
• Publikační typ
• časopisecké články MeSH

Biodegradable plastics play a vital role in addressing global plastics disposal challenges. Poly-3-hydroxybutyrate (P3HB) is a biodegradable bacterial intracellular storage polymer with substantial usage potential in agriculture. Poly-3-hydroxybutyrate and its degradation products are non-toxic; however, previous studies suggest that P3HB biodegradation negatively affects plant growth because the microorganisms compete with plants for nutrients. One possible solution to this issue could be inoculating soil with a consortium of plant growth-promoting and N-fixing microorganisms. To test this hypothesis, we conducted a pot experiment using lettuce (Lactuca sativa L. var. capitata L.) grown in soil amended with two doses (1 % and 5 % w/w) of P3HB and microbial inoculant (MI). We tested five experimental variations: P3HB 1 %, P3HB 1 % + MI, P3HB 5 %, P3HB 5 % + MI, and MI, to assess the impact of added microorganisms on plant growth and P3HB biodegradation. The efficient P3HB degradation, which was directly dependent on the amount of bioplastics added, was coupled with the preferential utilization of P3HB as a carbon (C) source. Due to the increased demand for nutrients in P3HB-amended soil by microbial degraders, respiration and enzyme activities were enhanced. This indicated an increased mineralisation of C as well as nitrogen (N), sulphur (S), and phosphorus (P). Microbial inoculation introduced specific bacterial taxa that further improved degradation efficiency and nutrient turnover (N, S, and P) in P3HB-amended soil. Notably, soil acidification related to P3HB was not the primary factor affecting plant growth inhibition. However, despite plant growth-promoting rhizobacteria and N2-fixing microorganisms originating from MI, plant biomass yield remained limited, suggesting that these microorganisms were not entirely successful in mitigating the growth inhibition caused by P3HB.

• Klíčová slova
• Agricultural production, Bioplastics, PGPR, Plant growth inhibition, Plastic pollution, Soil nutrients,
• MeSH
• biodegradace * MeSH
• hydroxybutyráty * metabolismus   MeSH
• látky znečišťující půdu metabolismus   MeSH
• mikrobiální společenstva fyziologie   MeSH
• mikrobiota MeSH
• polyestery * metabolismus   MeSH
• polyhydroxybutyráty MeSH
• půda chemie   MeSH
• půdní mikrobiologie * MeSH
• salát (hlávkový) metabolismus   mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydroxybutyráty * MeSH
• látky znečišťující půdu MeSH
• poly-beta-hydroxybutyrate MeSH Prohlížeč
• polyestery * MeSH
• polyhydroxybutyráty MeSH
• půda MeSH

Tissue engineering is a current trend in the regenerative medicine putting pressure on scientists to develop highly functional materials and methods for scaffolds' preparation. In this paper, the calibrated filaments for Fused Deposition Modeling (FDM) based on plasticized poly(3-hydroxybutyrate)/poly(d,l-lactide) 70/30 blend modified with tricalcium phosphate bioceramics were prepared. Two different plasticizers, Citroflex (n-Butyryl tri-n-hexyl citrate) and Syncroflex (oligomeric adipate ester), both used in the amount of 12 wt%, were compared. The printing parameters for these materials were optimized and the printability was evaluated by recently published warping test. The samples were studied with respect to their thermal and mechanical properties, followed by biological in vitro tests including proliferation, viability, and osteogenic differentiation of human mesenchymal stem cells. According to the results from differential scanning calorimetry and tensile measurements, the Citroflex-based plasticizer showed very good softening effect at the expense of worse printability and unsatisfactory performance during biological testing. On the other hand, the samples with Syncroflex demonstrated lower warping tendency compared to commercial polylactide filament with the warping coefficient one third lower. Moreover, the Syncroflex-based samples exhibited the non-cytotoxicity and promising biocompatibility.

• Klíčová slova
• additive manufacturing, bone scaffolds, fused deposition modeling, poly(3-hydroxybutyrate), polylactide, regenerative medicine, tissue engineering, tricalcium phosphate,
• Publikační typ
• časopisecké články MeSH