This work is focused on the comparison of macro-, micro- and nanomechanical properties of a series of eleven highly homogeneous and chemically very similar polymer networks, consisting of diglycidyl ether of bisphenol A cured with diamine terminated polypropylene oxide. The main objective was to correlate the mechanical properties at multiple length scales, while using very well-defined polymeric materials. By means of synthesis parameters, the glass transition temperature (Tg) of the polymer networks was deliberately varied in a broad range and, as a result, the samples changed their mechanical behavior from very hard and stiff (elastic moduli 4 GPa), through semi-hard and ductile, to very soft and elastic (elastic moduli 0.006 GPa). The mechanical properties were characterized in macroscale (dynamic mechanical analysis; DMA), microscale (quasi-static microindentation hardness testing; MHI) and nanoscale (quasi-static and dynamic nanoindentation hardness testing; NHI). The stiffness-related properties (i.e., storage moduli, indentation moduli and indentation hardness at all length scales) showed strong and statistically significant mutual correlations (all Pearson's correlation coefficients r > 0.9 and corresponding p-values < 0.001). Moreover, the relations among the stiffness-related properties were approximately linear, in agreement with the theoretical prediction. The viscosity-related properties (i.e., loss moduli, damping factors, indentation creep and elastic work of indentation at all length scales) reflected the stiff-ductile-elastic transitions. The fact that the macro-, micro- and nanomechanical properties exhibited the same trends and similar values indicated that not only dynamic, but also quasi-static indentation can be employed as an alternative to well-established DMA characterization of polymer networks.

• Klíčová slova
• crosslinked polymers, depth-sensing indentation, glass transition temperature, microindentation, nanoindentation, soft elastic rubbers, stiff vitrified networks,
• Publikační typ
• časopisecké články MeSH

The surface of fifteen polymethacrylate monolithic stationary phases has been modified by a post-polymerization UV-initiated grafting reaction with bifunctional poly(ethylene glycol)dimethacrylate monomers. An effect of crosslinking monomer length, its concentration in the modification mixture, and a time of the modification reaction have been selected to control the extent of modification by a design of experiments protocol. Hydrodynamic and kinetic properties of prepared columns were characterized by capillary liquid chromatography. Regression analysis of determined data revealed that there is only a minor effect of modification reaction on column permeability, as it is rather controlled by the composition of the polymerization mixture used to prepare generic monolith. On the other hand, the utilization of shorter crosslinking monomer increased the formation of small pores and minimized mass transfer resistance effect. Both column efficiency and mass transfer resistance also improved when a lower concentration of crosslinking monomer in the modification mixture was used. Photografting modification decreased a negative effect of mass transfer resistance related to a crosslink density gradient and allowed fast isocratic separations of dopamine metabolism-related compounds. Developed preparation protocol might be further utilized in the preparation of monolithic stationary phases in microfluidic devices.

• Klíčová slova
• Design of experiments, Grafting, Hypercrosslinking, Mass transfer resistance, Polymer monolith, Small molecules,
• MeSH
• chromatografie kapalinová MeSH
• permeabilita MeSH
• polymerizace MeSH
• polymery * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• polymery * MeSH

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.

• Klíčová slova
• Chitosan, Controlled drug release, Crosslinking, Drug-polymer solubility, Solvent casting, Transdermal delivery, Vanillin,
• MeSH
• benzaldehydy MeSH
• chitosan * MeSH
• enrofloxacin MeSH
• léky s prodlouženým účinkem MeSH
• polyvinylalkohol * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• benzaldehydy MeSH
• chitosan * MeSH
• enrofloxacin MeSH
• léky s prodlouženým účinkem MeSH
• polyvinylalkohol * MeSH
• vanillin MeSH Prohlížeč

To optimally exploit the potential of (tumor-) targeted nanomedicines, platform technologies are needed in which physicochemical and pharmaceutical properties can be tailored according to specific medical needs and applications. We here systematically customized the properties of core-crosslinked polymeric micelles (CCPM). The micelles were based on mPEG-b-pHPMAmLacn (i.e. methoxy poly(ethylene glycol)-b-poly[N-(2-hydroxypropyl) methacrylamide-lactate]), similar to the block copolymer composition employed in CriPec® docetaxel, which is currently in phase I clinical trials. The CCPM platform was tailored with regard to size (30 to 100nm), nanocarrier degradation (1month to 1year) and drug release kinetics (10 to 90% in 1week). This was achieved by modulating the molecular weight of the block copolymer, the type and density of the crosslinking agent, and the hydrolytic sensitivity of the drug linkage, respectively. The high flexibility of CCPM facilitates the development of nanomedicinal products for specific therapeutic applications.

• Klíčová slova
• Core-crosslinking, Drug release, Drug targeting, Nanomedicine, Polymeric micelles,
• MeSH
• akrylamidy chemie   MeSH
• docetaxel MeSH
• doxorubicin chemie   MeSH
• micely * MeSH
• molekulová hmotnost MeSH
• nosiče léků chemie   MeSH
• polymery chemie   MeSH
• reagencia zkříženě vázaná chemie   MeSH
• taxoidy chemie   MeSH
• uvolňování léčiv MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• akrylamidy MeSH
• docetaxel MeSH
• doxorubicin MeSH
• micely * MeSH
• N-(2-hydroxypropyl)methacrylamide MeSH Prohlížeč
• nosiče léků MeSH
• polymery MeSH
• reagencia zkříženě vázaná MeSH
• taxoidy MeSH

In recent years, porous materials have been extensively studied by the scientific community owing to their excellent properties and potential use in many different areas, such as gas separation and adsorption. Hyper-crosslinked porous polymers (HCLPs) have gained attention because of their high surface area and porosity, low density, high chemical and thermal stability, and excellent adsorption capabilities in comparison to other porous materials. Herein, we report the synthesis, characterization, and gas (particularly CO2) adsorption performance of a series of novel styrene-based HCLPs. The materials were prepared in two steps. The first step involved radical copolymerization of divinylbenzene (DVB) and 4-vinylbenzyl chloride (VBC), a non-porous gel-type polymer, which was then modified by hyper-crosslinking, generating micropores with a high surface area of more than 700 m2 g-1. In the following step, the polymer was impregnated with various polyamines that reacted with residual alkyl chloride groups on the pore walls. This impregnation substantially improved the CO2/N2 and CO2/CH4 adsorption selectivity.

• Klíčová slova
• CO2 adsorption, amine impregnation, dendrimer, gas separation, hyper-crosslinked porous polymer,
• Publikační typ
• časopisecké články MeSH

Tyrosinase is a common crosslinker used in the formation of in situ hydrogels, often resulting in significantly longer gelation times. The rate-determining step for the interconversion between the four discrete states of the enzyme is characterized by a lag phase, which contributes to its slow gelation kinetics. In this study, we report, for the first time, the use of a catalytic amount of iron(II) to produce fast in situ-gellable tyramine-conjugated hyaluronic acid hydrogels (HATA), which are prospectively applicable for nasal drug delivery. We observed gelation times ranging from 886 to 538 seconds, depending on the polymer and enzyme concentrations, irrespective of the pH level tested. The presence of iron(II) significantly reduced the gelation time by an order of magnitude, ranging from 86 seconds to 25.46 seconds, depending on the polymer concentration, pH, and enzyme activity. Based on our findings, we propose a double crosslinking mechanism involving catechol-catechol coupling and catechol-iron(II) complex formation, as evidenced by improvements in the rheological properties of the hydrogels. These novel hydrogels can encapsulate antibodies and provide prolonged release for up to two weeks. Additionally, we confirmed that the crosslinking chemistry did not affect the bioactivity of the antibodies. Given their improved mucoadhesive properties, we envision these hydrogels as promising candidates for the formulation of bioadhesive drug delivery systems.

• MeSH
• hydrogely * chemie   metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• kyselina hyaluronová * chemie   metabolismus   MeSH
• léky s prodlouženým účinkem chemie   MeSH
• lidé MeSH
• reagencia zkříženě vázaná chemie   MeSH
• tyrosinasa * metabolismus   chemie   MeSH
• uvolňování léčiv MeSH
• železo * chemie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydrogely * MeSH
• kyselina hyaluronová * MeSH
• léky s prodlouženým účinkem MeSH
• reagencia zkříženě vázaná MeSH
• tyrosinasa * MeSH
• železo * MeSH

Nowadays, research in the field of nanotechnology and nanomedicine has become increasingly predominant, focusing on the manipulation and development of materials on a nanometer scale. Polysaccharides have often been used as they are safe, non-toxic, hydrophilic, biodegradable and are low cost. Among them, starch derivatives and, in particular, cyclodextrin-based nanosponges (CD NSs) have recently emerged due to the outstanding properties attributable to their peculiar structure. In fact, alongside the common polysaccharide features, such as the presence of tunable functional groups and their ability to interact with biological tissues, thus giving rise to bioadhesion, which is particularly useful in drug delivery, what makes CD NSs unique is their three-dimensional network made up of crosslinked cyclodextrin units. The name "nanosponge" appeared for the first time in the 1990s due to their nanoporous, sponge-like structure and responded to the need to overcome the limitations of native cyclodextrins (CDs), particularly their water solubility and inability to encapsulate charged and large molecules efficiently. Since CD NSs were introduced, efforts have been made over the years to understand their mechanism of action and their capability to host molecules with low or high molecular weight, charged, hydrophobic or hydrophilic by changing the type of cyclodextrin, crosslinker and degree of crosslinking used. They enabled great advances to be made in various fields such as agroscience, pharmaceutical, biomedical and biotechnological sectors, and NS research is far from reaching its conclusion. This review gives an overview of CD NS research, focusing on the origin and key points of the historical development in the last 50 years, progressing from relatively simple crosslinked networks in the 1960s to today's multifunctional polymers. The approach adopted in writing the present study consisted in exploring the historical evolution of NSs in order to understand their role today, and imagine their future.

• Klíčová slova
• crosslinked polymer, cyclodextrin nanosponge, history,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

A novel approach to selectively modify narrow subareas of metallic nanostructures adjacent to plasmonic hotspots, where strong electromagnetic field amplification occurs upon localized surface plasmon (LSP) excitation, is reported. In contrast to surface plasmon-triggered polymerization, it relies on plasmonically enhanced multiphoton crosslinking (MPC) of polymer chains carrying photoactive moieties. When they are contacted with metallic nanostructures and irradiated with a femtosecond near-infrared beam resonantly coupled with LSPs, the enhanced field intensity locally exceeds the threshold and initiates MPC only at plasmonic hotspots. This concept is demonstrated by using gold nanoparticle arrays coated with two specifically designed polymers. Local MPC of a poly(N,N-dimethylacrylamide)-based copolymer with an anthraquinone crosslinker is shown via atomic force microscopy. Additionally, MPC is tested with a thermoresponsive poly(N-isopropylacrylamide)-based terpolymer. The reversible thermally induced collapse and swelling of the MPC-formed hydrogel at specific nanoparticle locations are confirmed by polarization-resolved localized surface plasmon resonance (LSPR) spectroscopy. These hybrid metallic/hydrogel materials can be further postmodified, offering attractive characteristics for future spectroscopic/bioanalytical applications.

• Publikační typ
• časopisecké články MeSH

The implantation of non-resorbable biocompatible polymer hydrogels into defects in the central nervous system can reduce glial scar formation, bridge the lesion and lead to tissue regeneration within the hydrogel. We implanted hydrogels based on crosslinked poly hydroxyethyl-methacrylate (pHEMA) and poly N-(2-hydroxypropyl)-methacrylamide (pHPMA) into the rat cortex and evaluated the cellular invasion into the hydrogels by means of immunohistochemical methods and tetramethylammonium diffusion measurements. Astrocytes and NF160-positive axons grew similarly into both types of hydrogels. We found no cell types other than astrocytes in the pHEMA hydrogels. In the pHPMA hydrogels, we found a massive ingrowth of connective tissue elements. These changes were accompanied by corresponding changes in the extracellular space volume fraction and tortuosity of the hydrogels.

• MeSH
• biokompatibilní materiály farmakologie   MeSH
• estery farmakologie   MeSH
• hydrogely farmakologie   MeSH
• krysa rodu Rattus MeSH
• methakryláty farmakologie   MeSH
• mozková kůra cytologie   účinky léků   zranění   fyziologie   MeSH
• pohyb buněk účinky léků   fyziologie   MeSH
• pojivová tkáň účinky léků   fyziologie   MeSH
• polyhydroxyethylmethakrylát farmakologie   MeSH
• polymery farmakologie   MeSH
• potkani Wistar MeSH
• preklinické hodnocení léčiv MeSH
• regenerace nervu účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• estery MeSH
• hydrogely MeSH
• methacryloylglycylglycine-4-nitrophenyl ester MeSH Prohlížeč
• methakryláty MeSH
• polyhydroxyethylmethakrylát MeSH
• polymery MeSH

This study reports the first Co2 (CO)8 -catalyzed [2+2+2] polycyclotrimerization by the transformation of internal ethynyl groups of aromatic diyne monomers. The reaction yields polycyclotrimers of polyphenylene-type with either hyperbranched or partly crosslinked architecture. The homopolycyclotrimerization of the monomers with two ethynyl groups per one molecule, namely 1,4-bis(phenylethynyl)benzene, 4,4'-bis(phenylethynyl)biphenyl, and 4-(phenylethynyl)phenylacetylene, gives partly crosslinked, insoluble polyphenylenes. The soluble, hyperbranched polyphenylenes are generated via copolycyclotrimerization of 1,4-bis(phenylethynyl)benzene with 1,2-diphenylacetylene (average number of ethynyl groups per monomer molecule < 2). This one-step polycyclotrimerization path to hyperbranched or partly crosslinked polyphenylenes is an alternative to the synthesis of these polymers by Diels-Alder transformation of substituted cyclopentadienones. All polyphenylenes prepared exhibit photoluminescence with emission maxima ranging from 381 to 495 nm. Polyphenylenes with a less compact packing of segments are microporous (specific surface area up to 159 m2 g-1 ), which is particularly important in the case of soluble polyphenylenes because they can be potentially used to prepare microporous layers.

• Klíčová slova
• internal diynes, microporous polymers, photoluminescence, polycyclotrimerization, polyphenylenes,
• MeSH
• diyny chemie   MeSH
• katalýza MeSH
• luminiscenční látky chemická syntéza   chemie   MeSH
• makromolekulární látky chemická syntéza   chemie   MeSH
• molekulární struktura MeSH
• polymerizace MeSH
• polymery chemie   MeSH
• poréznost MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• diyny MeSH
• luminiscenční látky MeSH
• makromolekulární látky MeSH
• polymery MeSH
• polyphenylene sulfide MeSH Prohlížeč