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A green, nature-friendly synthesis of polyaniline colloidal particles based on enzyme-assisted oxidation of aniline with horseradish peroxidase and chitosan or poly(vinyl alcohol) as steric stabilizers was successfully employed. Physicochemical characterization revealed formation of particles containing the polyaniline emeraldine salt and demonstrated only a minor effect of polymer stabilizers on particle morphology. All tested colloidal particles showed

Nucleated protein self-assembly of an azido modified spider silk protein was employed in the preparation of nanofibrillar networks with hydrogel-like properties immobilized on coatings of the same protein. Formation of the networks in a mild aqueous environment resulted in thicknesses between 2 and 60 nm, which were controlled only by the protein concentration. Incorporated azido groups in the protein were used to "click" short nucleic acid sequences onto the nanofibrils, which were accessible to specific hybridization-based modifications, as proved by fluorescently labeled DNA complements. A lipid modifier was used for efficient incorporation of DNA into the membrane of nonadherent Jurkat cells. Based on the complementarity of the nucleic acids, highly specific DNA-assisted immobilization of the cells on the nanohydrogels with tunable cell densities was possible. Addressability of the DNA cell-to-surface anchor was demonstrated with a competitive oligonucleotide probe, resulting in a rapid release of 75-95% of cells. In addition, we developed a photolithography-based patterning of arbitrarily shaped microwells, which served to spatially define the formation of the nanohydrogels. After detaching the photoresist and PEG-blocking of the surface, DNA-assisted immobilization of the Jurkat cells on the nanohydrogel microstructures was achieved with high fidelity.

An investigation was made into polymeric films based on polyvinylpyrrolidone (PVP) as the matrix, in combination with synthetic zeolite and dried or pyrolyzed biocarbon (biochar). The films were prepared by the casting method, and their properties were variously analysed (optical microscopy, FTIR analysis, differential scanning calorimetry, mechanical properties, water solubility, water uptake). Evaluation also encompassed the biological decomposition of the films in the soil environment and their influence on the growth of Sinapis alba. Optical microscopy indicated the particles of the fillers were almost completely evenly distributed in the polymer matrix, therein forming networks randomly. Since the space between the particles decreased as particle content increased, raising the content of the fillers brought about more compact networks. The IR spectra for the films proved the occurrence of hydrogen bonding between the PVP and synthetic zeolite. The processing and mechanical properties of the prepared polymeric films were acceptable. Water solubility and the water uptake of the films were satisfactory regarding handling and further use. Respirometric tests indicated a positive effect by the biocarbon on the biodegradation of the tested films. The proposed combination of synthetic zeolite and biocarbon fillers positively influenced the germination rate of Sinapis alba, while the polymer matrix (PVP) did not hinder further growth. Observations and testing led to the conclusion that the materials based on PVP with fillers (synthetic zeolite/biocarbon) have the potential for agricultural utilization.

This study investigates the effects of

The pseudo 3D hierarchical structure mimicking in vivo microenvironment was prepared by phase separation on tissue culture plastic. For surface treatment, time-sequenced dosing of the solvent mixture with various concentrations of polymer component was used. The experiments showed that hierarchically structured surfaces with macro, meso and micro pores can be prepared with multi-step phase separation processes. Changes in polystyrene surface topography were characterized by atomic force microscopy, scanning electron microscopy and contact profilometry. The cell proliferation and changes in cell morphology were tested on the prepared structured surfaces. Four types of cell lines were used for the determination of impact of the 3D architecture on the cell behavior, namely the mouse embryonic fibroblast, human lung carcinoma, primary human keratinocyte and mouse embryonic stem cells. The increase of proliferation of embryonic stem cells and mouse fibroblasts was the most remarkable. Moreover, the embryonic stem cells express different morphology when cultured on the structured surface. The acquired findings expand the current state of knowledge in the field of cell behavior on structured surfaces and bring new technological procedures leading to their preparation without the use of problematic temporary templates or additives., CZ.02.2.69/0.0/0.0/19_073/0016941, IGA/CPS/2022/001, IGA/FT/2022/009; Grantová Agentura České Republiky, GA ČR: 22-33307S, RP/CPS/2022/001, RP/CPS/2022/003, Czech Science FoundationGrant Agency of the Czech Republic [22-33307S]; project DKRVO [RP/CPS/2022/001, RP/CPS/2022/003]; TBU grant [IGA/FT/2022/009, IGA/CPS/2022/001]; OP RDE Junior Grants of TBU in Zlin [CZ.02.2.69/0.0/0.0/19_073/0016941]

Essential features of well-designed materials intended for 3D bioprinting via microextrusion are the appropriate rheological behavior and cell-friendly environment. Despite the rapid development, few materials are utilizable as bioinks. The aim of our work was to design a novel cytocompatible material facilitating extrusion-based 3D printing while maintaining a relatively simple and straightforward preparation process without the need for harsh chemicals or radiation. Specifically, hydrogels were prepared from gelatines coming from three sources-bovine, rabbit, and chicken-cross-linked by dextran polyaldehyde. The influence of dextran concentration on the properties of hydrogels was studied. Rheological measurements not only confirmed the strong shear-thinning behavior of prepared inks but were also used for capturing cross-linking reaction kinetics and demonstrated quick achievement of gelation point (in most cases < 3 min). Their viscoelastic properties allowed satisfactory extrusion, forming a self-supported multi-layered uniformly porous structure. All gelatin-based hydrogels were non-cytototoxic. Homogeneous cells distribution within the printed scaffold was confirmed by fluorescence confocal microscopy. In addition, no disruption of cells structure was observed. The results demonstrate the great potential of the presented hydrogels for applications related to 3D bioprinting., RP/CPS/2022/001; CZ.02.2.69/0.0/0.0/19_073/0016941; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: CZ.1.05/2.1.00/19.0376, RP/CPS/2022/003; Grantová Agentura České Republiky, GA ČR: 20-28732S, Ministry of Education, Youth and Sports of the Czech republic-DKRVO [RP/CPS/2022/003, RP/CPS/2022/001]; project OP RDE Junior Grants of TBU in Zlin [CZ.02.2.69/0.0/0.0/19_073/0016941]; CEBIA-Tech Instrumentation [CZ.1.05/2.1.00/19.0376]; Czech Science FoundationGrant Agency of the Czech Republic [20-28732S]

Novel bio-inspired conductive scaffolds composed of sodium hyaluronate containing water soluble polyaniline or polypyrrole colloidal particles (concentrations 0.108, 0.054 and 0.036 % w/w) were manufactured. For this purpose, either crosslinking with N-(3-dimethylaminopropyl-N-ethylcarbodiimide hydrochloride and N-hydroxysuccinimid or a freeze-thawing process in the presence of poly(vinylalcohol) were used. The scaffolds comprised interconnected pores with prevailing porosity values of ~30 % and pore sizes enabling the accommodation of cells. Good swelling capacity (92 – 97 %) without any sign of disintegration was typical for all samples. The elasticity modulus depended on the composition of the scaffolds, with the highest value of ~50 000 Pa obtained for the sample containing the highest content of polypyrrole particles. The scaffolds did not possess cytotoxicity and allowed cell adhesion and growth on the surface. Using the in vivo-mimicking conditions in a bioreactor, cells were also able to grow into the structure of the scaffolds. The technique of scaffold preparation used here thus overcomes the limitations of conducting polymers (e.g. poor solubility in an aqueous environment, and limited miscibility with other hydrophilic polymer matrices) and moreover leads to the preparation of cytocompatible scaffolds with potentially cell-instructive properties, which may be of advantage in the healing of damaged electro-sensitive tissues.

Bio-inspired conductive scaffolds composed of sodium hyaluronate containing a colloidal dispersion of water-miscible polyaniline or polypyrrole particles (concentrations of 0.108, 0.054 and 0.036% w/w) were manufactured. For this purpose, either crosslinking with N-(3-dimethylaminopropyl-N-ethylcarbodiimide hydrochloride and N-hydroxysuccinimid or a freeze-thawing process in the presence of poly(vinylalcohol) was used. The scaffolds comprised interconnected pores with prevailing porosity values of ~ 30% and pore sizes enabling the accommodation of cells. A swelling capacity of 92–97% without any sign of disintegration was typical for all samples. The elasticity modulus depended on the composition of the scaffolds, with the highest value of ~ 50 kPa obtained for the sample containing the highest content of polypyrrole particles. The scaffolds did not possess cytotoxicity and allowed cell adhesion and growth on the surface. Using the in vivo-mimicking conditions in a bioreactor, cells were also able to grow into the structure of the scaffolds. The technique of scaffold preparation used here thus overcomes the limitations of conductive polymers (e.g. poor solubility in an aqueous environment, and limited miscibility with other hydrophilic polymer matrices) and moreover leads to the preparation of cytocompatible scaffolds with potentially cell-instructive properties, which may be of advantage in the healing of damaged electro-sensitive tissues.

An innovative multi-step phase separation process was used to prepare tissue culture for the polystyrene-based, hierarchically structured substrates, which mimicked in vivo microenvironment and architecture. Macro-(pore area from 3000 to 18,000 µm2; roughness (Ra) 7.2 ± 0.1 µm) and meso-(pore area from 50 to 300 µm2; Ra 1.1 ± 0.1 µm) structured substrates covered with micro-pores (area around 3 µm2 ) were prepared and characterised. Both types of substrate were suitable for human-induced pluripotent stem cell (hiPSC) cultivation and were found to be beneficial for the induction of cardiomyogenesis in hiPSC. This was confirmed both by the number of promoted proliferated cells and the expressions of specific markers (Nkx2.5, MYH6, MYL2, and MYL7). Moreover, the substrates amplified the fluorescence signal when Ca2+ flow was monitored. This property, together with cytocompatibility, make this material especially suitable for in vitro studies of cell/material interactions within tissue-mimicking environments. © 2021 by the authors. Licensee MDPI, Basel, Switzerland., Grantová Agentura České Republiky, GA ČR: 18-18235S, 19-16861S, IGA//CPS/2021/001, IGA/FT/2021/010, Czech Science FoundationGrant Agency of the Czech Republic [19-16861S, 18-18235S]; TBU [IGA//CPS/2021/001, IGA/FT/2021/010]

This work investigates the effect of filler type on the rate of biodegradation of thermoplastic starch-based films in water and soil environments. The authors applied the casting method to create films of thermoplastic starch, based on waste paper, filled with clays or organic fillers. Since such materials made from cellulose tend to absorb water, we hydrophobized the surfaces of the filled thermoplastic starch samples. The structures of the blends were characterized by infrared spectroscopy, while atomic-force microscopy was applied to observe change in surface topography and the distribution of the filler. We also studied moisture resistance of the blends. Biodegradation tests revealed that surface topography, distribution of the filler and starch-to-filler interactions were non-critical to the rate and degree of biodegradation of the blends. The biodegradation rate of the blends was strongly affected by the environmental conditions (relative humidity 54%, 100%, respectively; temperature 25 °C, 37 °C, respectively). Under anaerobic conditions, it was the mixtures that biodegraded to the greatest extent, whereas the hydrophobized mixtures did so the least.

Self-assembly of a recombinant spider silk protein into nanofibrillar networks in combination with photolithography is used to produce diversely functionalized micropattern. Amino-modified substrates coated with a positive tone photoresist are processed into 1 mu m deep arbitrarily shaped microwells, at the bottom of which spider silk proteins are covalently coupled to the deprotected aminated surface. The protein layer serves to seed the self-assembly of nanofibrils from the same protein in the microwells, forming immobilized few nanometers thin networks after the stripping of the photoresist. The nanofibrous micropattern can be functionalized by employing fluorescently modified spider silk variants during the self-assembly or by later covalent modification with nucleic acids. By repeating the photolithography and fibril assembly procedures, two functionally different and spatially defined pattern are created., Bavarian-Czech Academic Agency (Bayerisch-Tschechische Hochschulagentur) BTHA Grant [JC-2019-21]; Czech Science Foundation [22-33307S]; TBU Grant [IGA/FT/2022/009]; Projekt DEAL, JC‐2019‐21; Tomas Bata University in Zlin, TBU: IGA/FT/2022/009; Grantová Agentura České Republiky, GA ČR: 22–33307S

A combination of mechanical and chemical treatments was utilized to modify the surface textures of copper and duralumin inserts in order to enhance the adhesion at the metal–polymer interface and provide an adhesive joint with a high loadbearing capacity. Pretreatment of the surfaces with sandblasting was followed by etching with various chemical mixtures. The resulting surface textures were evaluated with a scanning electron microscope (SEM) and an optical confocal microscope. Surface geometry parameters (Sa, Sz, and Sdr) were measured and their relationships to the adhesion joint strength were studied. It was found that the virgin and purely mechanically treated inserts resulted in joints with poor loadbearing capacity, while a hundredfold (duralumin) and ninetyfold (copper) increase in the force to break was observed for some combinations of mechanical and chemical treatments. It was determined that the critical factor is overcoming a certain surface roughness threshold with the mechanical pretreatment to maximize the potential of the mechanical/chemical approach for the particular combination of material and etchant. © 2021 by the authors. Licensee MDPI, Basel, Switzerland., RP/CPS/2020/003; IGA/FT/2021/010, Ministry of Education, Youth and Sports of the Czech Republic DKRVO [RP/CPS/2020/003]; TBU [IGA/FT/2021/010]

The conditions determining network-forming and aggregation properties of hyaluronan on the mica surface were studied. The hyaluronan was deposited on the surface from aqueous and saline solutions and attached by a bivalent cation. The morphology of the immobilized assemblies was characterized by atomic force microscopy. The experimental results show that the morphology and size of the aggregates as well as the density of the interconnecting fibrillar network, both made of hyaluronan, at the liquid-solid phase interface are determined not only by its molecular weight or concentration in solution, but also by the dissolution conditions and storage time. These findings extend the current state of knowledge about the conformational variability of this biologically important polymer. Understanding the conformational variability is of great importance, as it governs the physiological functions of hyaluronan, as well as its processability and formulations. That in turn determines its usability in different pharmacological and biomaterial applications.

Carboxylated cellulose nanocrystals (cCNC) were prepared by oxidation of microcrystalline cellulose with ammonium persulfate and characterized by AFM. Zeta potential was measured at different pH and ionic strength, in presence of mono- and divalent cations. With a length ranging from 50 to 450 nm and a thickness varying between 20 and 60 nm, the cCNC had a surface charge that appeared to be more sensitive to the presence of divalent cations and exhibited a strong pH dependence. The nanocrystals were capable of forming stable oil-in-water emulsions at three different pH of 2, 4 and 7 with a triglyceride oil. The size of emulsion droplets was dependent on oil and cCNC contents. Emulsification was, however, mainly influenced by the pH of the continuous phase, which can be related to reduction of charge on the cCNC surface with decreasing pH. Responsiveness of emulsions towards pH changes was not as dominant as expected, and lowering of pH did not trigger the release of oil from droplets. This can be explained by the strong adsorption of the cCNC, relatively polar triglyceride oil and the limited possibility to induce desorption of nanocrystals from oil surface.

Effects of the addition of water soluble glycinated Kraft lignin (WS/KL) on the mechanical stability and biocompatibility of hyaluronan (NaHy) hydrogels were evaluated in this work. Water soluble lignin was obtained by the modification of Kraft lignin via a Mannich reaction. It was found that WS/KL is highly compatible with hyaluronan due to its improved water solubility, which favours its use in designing new advanced composite hydrogels. The effects of the concentration of WS/KL on morphological, swelling and creep/recovery behaviours of hyaluronan hydrogels were investigated. It was detected that the creep resistance and creep recovery of NaHy hydrogels was improved by the incorporation of up to 3% (w/w) of WS/KL. In contrast, the swelling capacity of hydrogels was decreased. The cytotoxicity tests proved that glycinated KL lignin limits the viability of cells only slightly, and the final hyaluronan/lignin hydrogels were non-toxic materials.

In transdermal drug delivery applications uniform drug distribution and sustained release are of great importance to decrease the side effects. In this direction in the present research, vanillin crosslinked chitosan (CS) and polyvinyl alcohol (PVA) blend based matrix-type transdermal system was prepared by casting and drying of aqueous solutions for local delivery of enrofloxacin (ENR) drug. Subsequently, the properties including the morphology, chemical structure, thermal behavior, tensile strength, crosslinking degree, weight uniformity, thickness, swelling and drug release of the CS-PVA blend films before and after crosslinking were characterized. In vitro drug release profiles showed the sustained release of ENR by the incorporation of vanillin as a crosslinker into the CS-PVA polymer matrix. Furthermore, the release kinetic profiles revealed that the followed mechanism for all samples was Higuchi and the increase of vanillin concentration in the blend films resulted in the change of diffusion mechanism from anomalous transport to Fickian diffusion. Overall, the obtained results suggest that the investigated vanillin crosslinked CS-PVA matrix-type films are potential candidates for transdermal drug delivery system.

A novel approach to wet etching of silicon wafers (100) is described in this study. Homogenous organized surface structures were prepared by the utilization of self-organized flow in the etching solution (Benard-Marangoni thermocapillar instability). The driving force behind this process is a temperature gradient generated by the etching apparatus exclusively constructed for this research. The influences of temperature gradients (1–20 K) and etching time (20–55 min) were studied, with the potassium hydroxide/isopropyl alcohol etching solution. Obtained results indicate that self-organized flow can be utilized for specific and rapid etching, which allows significant variation of the topography and reflectivity of the silicon wafer surface textured in this way.

A special apparatus allowing for the targeted modification of the physicochemical characteristics of dispersive systems via a self-organised liquid flow (Benard-Marangoni or Railegh-Benard instability) was constructed. The apparatus was tested by means of heat transfer rate and temperature distribution uniformity over a newly-designed composite heating plate. New types of a solidification cell and a condenser were developed for polymer solution solidification in temperature gradients, at low pressure or in a defined atmosphere. Two polysaccharide systems were used to demonstrate the abilities of the apparatus. The results demonstrate how significant an effect the self-organised liquid flow can have on the arrangement of macromolecular systems in solutions, at phase boundaries or in solidified polymer foils.

In the current study, we present methods of sodium hyaluronate, also denoted as hyaluronan (HA), nanofiber fabrication using a direct-current (DC) electric field. HA was spun in combination with poly(vinyl alcohol) (PVA) and polyethylene oxide (PEO) and as a pure polymer. Nonaggressive solvents were used due to the possible use of the fibers in life sciences. The influences of polymer concentration, average molecular weight (Mw), viscosity, and solution surface tension were analyzed. HA and PVA were fluorescent-labeled in order to examine the electrospun structures using fluorescence confocal microscopy. In this study, two intermediate solvent mixtures that facilitate HA electrospinning were found. In the case of polymer co-electrospinning, the effect of the surfactant content on the HA/PVA electrospinning process, and the effect of HA Mw on HA/PEO nanofiber morphology, were examined, respectively.

The ways of producing porous-like textured surfaces with chemical etching on aluminum-alloy substrates were studied. The most appropriate etchants, their combination, temperature, and etching time period were explored. The influence of a specifically textured surface on adhesive joints' strength or superhydrophobic properties was evaluated. The samples were examined with scanning electron microscopy, profilometry, atomic force microscopy, goniometry, and tensile testing. It was found that, with the multistep etching process, the substrate can be effectively modified and textured to the same morphology, regardless of the initial surface roughness. By selecting proper etchants and their sequence one can prepare new types of highly adhesive or even superhydrophobic surfaces. © 2018 by the authors., Ministry of Education, Youth, and Sports of the Czech Republic-Program NPU I [LO1504]; European Regional Development Fund [CZ.1.05/2.1.00/19.0409]; TBU grant [IGA/FT/2017/011, IGA/FT/2018/011]

Dynamic light scattering (DLS), viscosity and surface tension (SFT) measurements were used to characterize influence of salts containing ions of Hofmeister series (Na 2 SO 4 , (NH 4 ) 2 SO 4 , NaSCN, NH 4 SCN and NaCl) on the behaviour of hyaluronan in diluted solutions at a temperature range of 15–45 °C. The results of the study showed that chaotropic and kosmotropic ions notably influenced the folding and unfolding of hyaluronan coils due to interactions between a respective ion and hydrophilic or hydrophobic patches present in the backbone of the polymer chains. This was mainly proved by viscosity and light scattering measurements. The temperature dependence of the hydrodynamic diameter of the hyaluronan coil determined by DLS demonstrated that combinations of chaotropic and kosmotropic ions in one salt (NaCl, NaSCN and (HN 4 ) 2 SO 4 ) can stabilize the size of the coil in a wide range of temperatures. Tensiometry measurements indicated that certain types of ions present in the solution caused an unfolding of the hyaluronan coils, leading to a decrease of SFT. © 2019 Elsevier Ltd, Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]; TBU in Zlin [IGA/FT/2017/011, IGA/FT/2018/011, IGA/FT/2019/012]

Foamed phase-change materials (FPCMs) were prepared using recycled linear low-density polyethylene (LLDPE) blended with 30 wt.% of paraffin wax (PW) and foamed by 1,1 '-azobiscarbamide. The protection of pores' collapse during foaming process was insured through chemical cross-linking by organic peroxide prior foaming. This work represents one of very few attempts for a preparation of polymeric phase change foams without a use of micro-encapsulated phase change component leading to the enhancement of the real PCM component (PW) within a final product. The porous structure of fabricated foams was analyzed using micro-computed tomography, and direct observation, and reconstruction of the internal structure was investigated. The porosity of FPCMs was about 85-87 vol.% and resulting thermal conductivity 0.054-0.086 W/m center dot K. Differential Scanning Calorimetry was used to determine the specific enthalpies of melting (22.4-25.1 J/g) what is the latent heat of materials utilized during a heat absorption. A stability of samples during 10 heating/cooling cycles was demonstrated. The phase change changes were also investigated using the dynamic mechanical analysis from 0 degrees to 65 degrees C during the 10 cycles, and the mechanical stability of the system and phase-change transition were clearly confirmed, as proved by DSC. Leaching test revealed a long-term release of PW (around 7% of its original content) from samples which were long term stored at temperatures over PW melting point. This is the usual problem concerning polymer/wax blends. The most common, industrially feasible solution is a lamination of products, for instance by aluminum foils. Finally, the measurement of the heat flow simulating the real conditions shows that samples containing PW decrease the energy passing through the sample from 68.56 to 34.88 kJ center dot m(-2). In this respect, FPCMs provide very effective double functionality, firstly common thermal insulators, and second, as the heat absorbers acting through melting of the PW and absorbing the excessive thermal energy during melting. This improves the heat protection of buildings and reduces temperature fluctuations within indoor spaces., Qatar National Research Fund (A Member of the Qatar Foundation) [13S-0127-200177]; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2020/003], RP/CPS/2020/003; Qatar Foundation, QF; Qatar National Research Fund, QNRF; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT

Tracer diffusion coefficients obtained from the Taylor dispersion technique at 25.0◦C were measured to study the influence of sodium, ammonium and magnesium salts at 0.01 and 0.1 mol dm−3 on the transport behavior of sodium hyaluronate (NaHy, 0.1%). The selection of these salts was based on their position in Hofmeister series, which describe the specific influence of different ions (cations and anions) on some physicochemical properties of a system that can be interpreted as a salting-in or salting-out effect. In our case, in general, an increase in the ionic strength (i.e., concentrations at 0.01 mol dm−3 ) led to a significant decrease in the limiting diffusion coefficient of the NaHy 0.1%, indicating, in those circumstances, the presence of salting-in effects. However, the opposite effect (salting-out) was verified with the increase in concentration of some salts, mainly for NH4SCN at 0.1 mol dm−3 . In this particular salt, the cation is weakly hydrated and, consequently, its presence does not favor interactions between NaHy and water molecules, promoting, in those circumstances, less resistance to the movement of NaHy and thus to the increase of its diffusion (19%). These data, complemented by viscosity measurements, permit us to have a better understanding about the effect of these salts on the transport behaviour of NaHy. © 2021 by the authors. Licensee MDPI, Basel, Switzerland., Fundacao para a Ciencia e a Tecnologia (FCT) through COMPETE Programme (Operational Programme for Competitiveness) [UIDB/QUI/00313/2020]; Ministry of Education, Youth and Sports of the Czech Republic DKRVO [RP/CPS/2020/003], Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2020/003; Fundação para a Ciência e a Tecnologia, FCT: UIDB/QUI/00313/2020

Novel composite films combining biocompatible polysaccharides with conducting polyaniline (PANI) were prepared via the in-situ polymerization of aniline hydrochloride in the presence of sodium hyaluronate (SH) or chitosan (CH). The composite films possess very good cytocompatibility in terms of adhesion and proliferation of two lines of human induced pluripotent stem cells (hiPSC). Moreover, the cardiomyogenesis and even formation of beating clusters were successfully induced on the films. The proportion of formed cardiomyocytes demonstrated excellent properties of composites for tissue engineering of stimuli-responsive tissues. The testing also demonstrated antibacterial activity of the films against E. coli and PANI-SH was able to reduce bacterial growth from 2 × 105 to < 1 cfu cm-2. Physicochemical characterization revealed that the presence of polysaccharides did not notably influence conductivities of the composites being ∼1 and ∼2 S cm-1 for PANI-SH and PANI-CH respectively; however, in comparison with neat PANI, it modified their topography making the films smoother with mean surface roughness of 4 (PANI-SH) and 14 nm (PANI-CH). The combination of conductivity, antibacterial activity and mainly cytocompatibility with hiPSC opens wide application potential of these polysaccharide-based composites.

Conjugated polyelectrolyte with polythiophene main chain and imidazolium side groups, poly{3-[6-(1-methylimidazolium-3-yl) hexyl]thiophene-2,5-diyl bromide}, is investigated. Polymer architecture with hydrophobic main chain and hydrophilic side groups is responsible for the inconvenient behavior of the polymer in solution. Absorption and emission characteristics and supramolecular assembling are investigated by spectroscopic, microscopic and light-scattering methods. We report significant solvatochromism which is observable by a naked eye. Water solutions and mixed solvent systems exhibit most interesting features: supramolecular assembling was investigated by DLS, AFM and TEM techniques and common spectroscopic methods such as UV–vis and fluorescence spectroscopy. Moreover, slow relaxation processes take part in water as it is evidenced by time evolution of absorption spectra. It is a result of vanishing of inter- and intramolecular interactions. These interactions are responsible for extraordinary solution behavior of the ionic polythiophene.

Polyaniline is a promising conducting polymer with broad application potential in biomedicine. Its medical use, however, requires both biocompatibility and suitable physico-chemical and surface properties. The microstructure, electrical properties, and surface characteristics of polyaniline salt, polyaniline base, and polyaniline deposited with biologically active poly(2-acrylamido-2-methyl-1-propanesulfonic acid) were revealed using atomic force microscopy, contact angle measurements, and Raman spectroscopy. As conducting polymers can be preferentially applied in tissue engineering of heart and nervous tissues, the cardiomyogenesis in pure cardiomyocytes derived from embryonic stem cells and neurogenesis in neural progenitors isolated from embryonal 13 dpc brain were further investigated. The results show that neither cardiomyogenesis nor neurogenesis were influenced by any of the tested polyaniline films. However, the most favorable cell behaviour was observed on pristine polyaniline base; therefore, polyaniline in pristine forms without any further modification can be applied in a variety of biomedical fields.

Poly(dimethyl siloxane) (PDMS)-based materials with improved photoactuation properties were prepared by the incorporation of polymer-grafted graphene oxide particles. The modification of the graphene oxide (GO) surface was achieved via a surface initiated atom transfer radical polymerization (SI ATRP) of methyl methacrylate and butyl methacrylate. The modification was confirmed by thermogravimetric analysis, infrared spectroscopy and electron microscopy. The GO surface reduction during the SI ATRP was investigated using Raman spectroscopy and conductivity measurements. Contact angle measurements, dielectric spectroscopy and dynamic mechanical analyses were used to investigate the compatibility of the GO filler with the PDMS matrix and the influence of the GO surface modification on its physical properties and the interactions with the matrix. Finally, the thermal conductivity and photoactuation properties of the PDMS matrix and composites were compared. The incorporation of GO with grafted polymer chains, especially poly(n-butyl methacrylate), into the PDMS matrix improved the compatibility of the GO filler with the matrix, increased the energy dissipation due to the improved flexibility of the PDMS chains, enhanced the damping behavior and increased the thermal conductivity. All the changes in the properties positively affected the photoactuation behavior of the PDMS composites containing polymer-grafted GO. © 2017 by the authors., LO1504, MOE, Ministry of Education, Grant Agency of the Czech Republic [16-20361Y]; Ministry of Education, Youth and Sports of the Czech Republic-program NPU I [LO1504]; SRDA [APVV-15-0545]; VEGA [VEGA 2/0161/17]; Slovak Academy of Sciences [SAS-MOST JRP 2014-9]

A new approach to polystyrene surface treatment via the time-sequenced dispensing of good and poor solvent mixtures on the rotating surface of treated substrate is presented in this study. It is demonstrated that the variation of the sequencing together with other variables (e.g., temperature and solvent concentration) affects the size and depth of pores evolving on the polystyrene surface. A model of the surface pore creation, associated with the viscoelastic phase separation, surface tension, and secondary flows caused by temperature variations and the rapid evaporation of the good solvent is proposed. Experimental results of profilometric, goniometric, and optical measurements show that this approach enables the simple and quick preparation of surfaces with various numbers, diameters, and depths of individual pores, which ultimately affects not only the wetting characteristics of the surfaces but also the fate of cells cultivated there. The presented method allows the easy preparation of a large number of structured substrates for effective cell cultivation and proliferation. © 2017 American Chemical Society., CZ.1.05/2.1.00/19.0409, ERDF, European Regional Development Fund; MOE, Ministry of Education, Operational Program Research and Development for Innovations - European Regional Development Fund (ERDF); national budget of the Czech Republic within the framework of the project Centre of Polymer Systems [CZ.1.05/2.1.00/03.0111]; Ministry of Education, Youth and Sports of the Czech Republic, Program NPU I [LO1504]; European Regional Development Fund [CZ.1.05/2.1.00/19.0409]; TBU [IGA/FT/2015/014, IGA/FT/2016/013]

The effect of the substrate surface free energy on the formation of organised structures developed during solvent evaporation was studied. Aqueous solution of 2-hydroxyethyl cellulose in temperature gradient under the Benard–Marangoni convective flow conditions was used as a model system. Polystyrene was used as a model substrate and its surface properties were modified with the low-temperature plasma. Changes in the substrate surface and their stability were monitored with contact angle measurement and atomic force microscopy. Solidification of the polymeric solutions was carried out in the specially constructed apparatus (Micro-condensation drying system) at defined temperature gradient and solvent evaporation rate. The effect of molecular weight distribution width, time of substrate surface plasma treatment, homogeneity of plasma treatment, size of the container with the polymeric solution and polymeric solution initial height was examined. Experimental results indicate crucial influence of the substrate surface energy on the development of self-organised patterns in films solidified from diluted polymeric solutions with broad molecular weight distribution.

The cytocompatibility of cardiomyocytes derived from embryonic stem cells and neural progenitors, which were seeded on the surface of composite films made of graphene oxide (GO) and polypyrrole (PPy-GO) or poly(3,4-ethylenedioxythiophene) (PEDOT-GO) are reported. The GO incorporated in the composite matrix contributes to the patterning of the composite surface, while the electrically conducting PPy and PEDOT serve as ion-to-electron transducers facilitating electrical stimulation/sensing. The films were fabricated by a simple one-step electropolymerization procedure on electrically conducting indium tin oxide (ITO) and graphene paper (GP) substrates. Factors affecting the cell behaviour, i.e. the surface topography, wettability, and electrical surface conductivity, were studied. The PPy-GO and PEDOT-GO prepared on ITO exhibited high surface conductivity, especially in the case of the ITO/PPy-GO composite. We found that for cardiomyocytes, the PPy-GO and PEDOT-GO composites counteracted the negative effect of the GP substrate that inhibited their growth. Both the PPy-GO and PEDOT-GO composites prepared on ITO and GP significantly decreased the cytocompatibility of neural progenitors. The presented results enhance the knowledge about the biological properties of electroactive materials, which are critical for tissue engineering, especially in context stimuli-responsive scaffolds.

The nanotexturing of microstructured polystyrene surfaces through CF4 plasma chemical fluorination is presented in this study. It is demonstrated that the parameters of a surface micropore-generation process, together with the setup of subsequent plasma-chemical modifications, allows for the creation of a long-term (weeks) surface-stable micro- and nanotexture with high hydrophobicity (water contact angle &gt, 150&deg, ). Surface micropores were generated initially via the time-sequenced dosing of mixed solvents onto a polystyrene surface (Petri dish) in a spin-coater. In the second step, tetrafluoromethane (CF4) plasma fluorination was used for the generation of a specific surface nanotexture and the modulation of the surface chemical composition. Experimental results of microscopic, goniometric, and spectroscopic measurements have shown that a single combination of phase separation methods and plasma processes enables the facile preparation of a wide spectrum of hierarchically structured surfaces differing in their wetting properties and application potentials.

The influence of cultivation methods and postharvesting treatment on protein profiles of green freshwater microalgae Chlorella kessleri, Scenedesmus quadricauda, and Chlorella sp. and cyanobacterium Spirulina platensis were evaluated. The comparison of protein profiles in algal biomass originated from the autotrophic cultivation in an outdoor open circulating cascade-type cultivation apparatus in thin-layer, a solar photobioreactor, and from the heterotrophic cultivation regime in a fermenter. All tested algae contained protein bands in the area between 14.3-27 and 70-116 kDa. Protein profiles revealed much higher heterogenity in the area between 30-70 kDa. © 2016 Taylor & Francis., projects of the internal grants of Tomas Bata University in Zlin [IGA/22/FT/11/D, IGA/FT/2012/038/D]

This paper is focused on the chemical and morphology changes in the surface of poly(1-butene) (PB-1) generated by plasma treatment. The radio frequency capacitively coupled plasma (air, argon, argon then allylamine, argon containing ammonia and argon with octafluorocyclobutane) was used. Modified surface of PB-1 was characterized by contact angle measurements, X-ray photoelectron spectroscopy, and atomic force microscopy. The surface hydrophilization by air and argon with ammonia plasmas was evaluated as most sufficient. Oppositely, a high level of hydrophobicity of PB-1 surface was reached by combination of argon with octafluorocyclobutane plasma. Upon plasma modification, hydrophilicity/hydrophobicity of treated surfaces remained stable within three days under air atmosphere and then values of contact angle slowly recovered to those of unmodified PB-1. However, morphology and surface chemical composition of plasma-modified samples remained generally unchanged during observed time. Changes in surface hydrophilicity/hydrophobicity of plasma-treated PB-1 were attributed to variance of conformation of the surface molecules.

Factors determining creation of self-organized structures, Benar–Marangoni cells, during the process of solvent evaporation from the polymer solution and formation of polymer film were studied. Examined parameters were temperature, temperature gradient, rate of drying, height of a liquid layer, area for film preparation, viscosity, molecular weight distribution, etc. A special apparatus, micro condensation drying system, was engineered for this study. As a model system, hydroxyethyl cellulose aqueous solution was used for its excellent film-forming ability and the tendency to self-aggregation. Experimental results, presented in a wide spectrum of self-organized patterns, show the complexity of the problem and the crucial role of molecular weight distribution of the polymer in the fixation of organized structures under highly non-equilibrium conditions.

Special micro-condensation drying system (MCDS) was constructed for precise preparation of self-organized polymeric layers by casting from solutions and dispersions at highly non-equilibrium conditions. There were respected the needs for exact regulation of temperature, temperature gradient and rate of solvent evaporation, vibration damping, dust-free design and wide variability in process parameters settings as well. MCDS allows to study a broad spectrum of effects determining creation of self-organized structures during the evaporation of solvent from the polymer solution (e.g. Rayleigh–Benard or Benard–Marangoni cells). As a model system for MCDS functionality testing aqueous solution of hydroxyethyl-cellulose was chosen, with respect to its excellent film-forming properties and the self-organization ability. All of this is observable in high number of cell patterns, originating according to the process parameters, in the given polymer-solution system.

The process of diffusion of sodium hyaluronate and its hydrophobically modified alkyl derivatives in water was studied by measuring the kinetics of solid polymer film swelling. The following fundamental thermodynamic parameters of the swelling process were calculated: the apparent diffusion coefficient of swelling by water D(s) determined at three temperatures (25, 37, and 45 degrees C), the activation enthalpy of diffusion connected with the swelling DeltaH(D,s) and the activation enthalpy of the swelling process DeltaH(s). The thermodynamic activity of the solvent for the given sodium hyaluronate and its four alkyl derivatives has been expressed through the internal quantity RA(delta,s), that is expansion work of polymer coil accomplished by the action of the internal pressure.

Hyaluronan (HA) films exhibit properties suitable for various biomedical applications, but the solubility of HA limits their use in aqueous environments. Therefore, we developed water insoluble films based on palmitoyl esters of HA (pHA). Films were prepared from pHA samples with various degrees of substitution (DS) and molecular weights and their mechanical properties and swelling were characterized. Additionally, scanning electron microscopy and atomic force microscopy were used for visualization. Despite being prepared by solution casting, the films had a very smooth surface and were homogeneous in thickness. The film properties were in accordance with the polymer DS and molecular weight, enabling to tailor them for future applications by choosing a suitable pHA material. The behavior of the films toward cells was assessed in vitro. All films were non-cytotoxic and showed no adhesion of cells. These results show that the developed films are suitable candidates for various biomedical applications such as tissue engineering or wound healing.

Mutual diffusion coefficients, D, were determined for aqueous solutions of sodium hyaluronate (NaHy) at 25 °C and concentrations ranging from 0.00 to 1.00 g·dm(-3) using the Taylor dispersion technique. From these experimental data, it was possible to estimate some parameters, such as the hydrodynamic radius Rh, and the diffusion coefficient at infinitesimal concentration, D0, of hyaluronate ion, permitting us to have a better understanding of the structure of these systems of sodium hyaluronate in aqueous solutions. The additional viscosity measurements were done and Huggins constant, kH, and limiting viscosity number, [η], were computed for interaction NaHy/water and NaHy/NaHy determination.

This study investigated an effect of different ways of the preparation of insoluble hyaluronan material on its mechanical and viscoelastic properties. Hyaluronan (NaHy) of molecular weight Mw=500,000 g mol(-1) was modified with N-(3-dimethylaminopropyl-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), to be able absorb liquid without changing its mechanical properties. The modified, water insoluble NaHy materials were prepared in different geometry; as modified films and modified cylinders with exact dimensions. The occurrence of modification was confirmed by FT-IR (Fourier transform infrared spectroscopy) and (1)H NMR (proton nuclear magnetic resonance) spectroscopy and swelling test. The determined mechanical and viscoelastic properties of unmodified and modified hyaluronan revealed the high dependency of elasticity changes depending on the gel processing method. Moreover, NaHy gels in the cylindrical form with the sponge-like structure predominant them as a convenient geometry for application in a humid environment.

Interaction of hyaluronan (NaHy) with the quaternary salt, benzalkonium chloride (BAC), was studied. Based on the DLS experiments, viscometry and surface tension measurements executed on hyaluronan samples with two molecular weights of M w = 1.8 MDa and M w = 0.35 MDa, the hypothesis was proposed suggesting that at certain BAC concentrations, hyaluronan can form aggregates, which lead to increase of the polymer coil size measured as z -average diameter. Moreover, it was confirmed that within the whole range of BAC concentrations, repeated variations in size and conformations of polymer coils occur, being connected with the critical micellar concentration of BAC and with hydrophobic interactions of non-polar segments of BAC with hyaluronan hydrophobic domains. Tensiometry, DLS and viscometry data support the assumption that variations of thermodynamical “favourability” of BAC–BAC or NaHy–BAC interactions take place in hyaluronan solutions, based on the BAC concentration.