Synthesis of pyrrole-cyclodextrin conjugates for tissue engineering

Tato práce si klade za cíl připravit pokročilý materiál pro tkáňové inženýrství a především hlouběji pochopit vliv povrchové úpravy na interakci substrátu s biologickou hmotou. Tento materiál dále poslouží jako platforma pro cílovou aplikaci v oblasti regenerace nervové tkáně. Navzdory intenzivnímu výzkumu v průběhu posledních několika dekád trpí tkáňové nosiče řadou nedostatků. Jedním z nich je netečnost implantátů, které neposkytují nezbytné podněty pro stimulaci buněčného růstu. Současná analytická chemie však disponuje širokou paletou metod, které nám pomáhají pochopit základní děje probíhající při interakci biologické hmoty s povrchem materiálu. Tyto nástroje také hrají důležitou roli při designování nových tkáňových nosičů, které dnes mohou být připraveny řadou pokročilých metod. Nejen proto jsme se rozhodli zkombinovat znalosti z několika různých oblastí a vytvořit postup pro přípravu pokročilého materiálu se zajímavými vlastnostmi pro tkáňové inženýrství. Námi navržený tkáňový nosič je postaven na 3D vlákenné polymerní síti, která byla vyrobena elektrostatickým zvlákňováním. Tato technika umožňuje produkci vlákenného materiálu s variabilními mechanickými vlastnostmi, morfologií nebo stabilitou ve fyziologickém prostředí. Ačkoliv elektrostatické zvlákňování produkuje náhodně uspořádaná vlákna, tak poskytuje dobrou kontrolu nad průměrem vláken či tloušťkou vznikající vrstvy. Orientace vláken dále propůjčuje materiálu schopnost ovlivňovat směr růstu buněk.Je obecně známo, že interakce většiny typů buněk s materiálem je zprostředkována adhezními proteiny. Tyto biomolekuly jsou adsorbovány na povrchu a následně rozpoznány specifickými membránovými receptory. Záměrem našeho výzkumu je v první řadě syntéza pyrrol-cyklodextrinových derivátů, které mohou být následně deponovány na povrch zvoleného materiálu. Alternativní cestou je pokrytí vlákenného substrátu vhodným beta-substituovaným derivátem polypyrrolu, jehož funkční skupiny budou v následném kroku využity pro navázání cyklodextrinových makrocyklů. Věříme, že lipofilní kavita cyklodextrinu umožní díky slabým nevazebným interakcím s proteiny jejich přitažení k povrchu, čímž dojde k vytvoření struktury připomínající extracelulární hmotu. Tato interakce povede k adsorpci proteinů v jejich přirozené prostorové konformaci, což bude mít za následek lepší adhezi a proliferaci buněk. Povrchová vrstva vodivého polypyrrolu může být navíc využita k elektrické stimulaci růstu buněk. Očekáváme, že studium takového tkáňového nosiče přinese zajímavé informace o interakci buněk s materiálem a otevře cestu k pokročilým biologicky aktivním materiálům pro tkáňové inženýrství.This thesis aims to prepare new composite material for tissue engineering and to understand the effect of surface functionalization on the cell-material interaction. This scaffold will serve as a primary platform for future development towards its ultimate application in the field of nervous tissue regeneration. Despite decades of intensive research, the majority of implants suffers from many drawbacks. One of them is the inertness of material which cannot provide essential cues for cell stimulation and growth. However, contemporary analytical chemistry together with advanced techniques for materials synthesis offers considerable variability in scaffolds design. Therefore, we have decided to combine knowledge from several different research areas and create procedures for the preparation of novel materials with exciting features. Our scaffold is based on the 3D fibrous polymeric network made by electrospinning process. This technique enables the production of materials with tunable mechanical properties, morphology or stability in the physiological environment. Although electrospinning is a random process, there is reasonable control over the diameter and morphology of the fibres. Other indisputable advantages are high productivity and the possibility of incorporating various compounds, nanoparticles or even biomolecules into the fibrous structure. Moreover, aligned fibres can also be prepared using a rotating collector or by drawing technique which is under intensive development in cooperation with our colleagues. The orientation of fibres also imparts another level of control over the cell adhesion and growth.It is generally known that adhesive proteins mediate cell-material interaction. These biomolecules are absorbed onto the surface and are recognised by specific membrane receptors. Therefore, one option of our research is the synthesis of pyrrole-cyclodextrin monomers which could be copolymerized with pyrrole creating desirable core-shell material with cyclodextrin decorated surface. The alternative route would be based on the preparation of a fibrous matrix with deposited beta-substituted polypyrrole layer. In the next step, suitable binding places would be utilised for the final cyclodextrin immobilisation. We believe, that cyclodextrin lipophilic cavity could attract adhesion mediating proteins by non-bonding interaction and thus create extracellular matrix mimicking structures on the surface. Such interactions allow absorption of proteins in their natural spatial conformation which ultimately leads to significantly better cell adhesion and growth. Moreover, the core-shell 3D matrix with a deposited conductive polypyrrole layer on the surface could be used for cell guidance by external electric stimulation. The study of the scaffold mentioned above should bring us new information about cell-material interaction and make a step forward to the future bioresponsive material for tissue engineering

Facetted Moldavites

Fluvio-lacustral sediments of Tertiary (Pliocene, lower Rumanian) on several locations in South Bohemia occur. These sediments are probably formed by activities of paleoriver Blanice and Radomilický brook. Sediments were many times redeposited on gravel terrace. In recent relics of these sediments facetted boulders of quartz and other solid material were found.Moldavites from strewn field of Radomilice area are tied on these positions of gravel sands. Gravel sediments with moldavites were several times redeposited and therefore there are rounded stones with distinct abrasion. Frequent findings of facetted boulders caused the study of moldavites from these locations. Occurences of facetted moldavites has been confi rmed – Březí, Dříteň, Dubenec and Zbudov. Their occurence can be expected at the sites with similar conditions. Also we can assume that Tertiary sediments formed large position at elevated plains. Such uncovered plains were exposed during the period with low vegetation to intense eolic activity. Ideal conditions for the formation of facetted boulders and moldavites were in the Pleistocene, when dry, cold and windy conditions prevailed along with lack of vegetation cover. Facetted moldavites are uniquely complicated evidence of the origin and evolution of this interesting geologic phenomenon and their bearing sediments.Fluvio-lacustral sediments of Tertiary (Pliocene, lower Rumanian) on several locations in South Bohemia occur. These sediments are probably formed by activities of paleoriver Blanice and Radomilický brook. Sediments were many times redeposited on gravel terrace. In recent relics of these sediments facetted boulders of quartz and other solid material were found.Moldavites from strewn field of Radomilice area are tied on these positions of gravel sands. Gravel sediments with moldavites were several times redeposited and therefore there are rounded stones with distinct abrasion. Frequent findings of facetted boulders caused the study of moldavites from these locations. Occurences of facetted moldavites has been confi rmed – Březí, Dříteň, Dubenec and Zbudov. Their occurence can be expected at the sites with similar conditions. Also we can assume that Tertiary sediments formed large position at elevated plains. Such uncovered plains were exposed during the period with low vegetation to intense eolic activity. Ideal conditions for the formation of facetted boulders and moldavites were in the Pleistocene, when dry, cold and windy conditions prevailed along with lack of vegetation cover. Facetted moldavites are uniquely complicated evidence of the origin and evolution of this interesting geologic phenomenon and their bearing sediments

Synthesis and Surface Behaviour of NDI Chromophores Mounted on a Tripodal Scaffold: Towards Self-Decoupled Chromophores for Single-Molecule Electroluminescence

This paper reports the efficient synthesis, absorption and emission spectra, and the electrochemical properties of a series of 2,6-disubstituted naphthalene-1,4,5,8-tetracarboxdiimide (NDI) tripodal molecules with thioacetate anchors for their surface investigations. Our studies showed that, in particular, the pyrrolidinyl group with its strong electron-donating properties enhanced the fluorescence of such core-substituted NDI chromophores and caused a significant bathochromic shift in the absorption spectrum with a correspondingly narrowed bandgap of 1.94 eV. Cyclic voltammetry showed the redox properties of NDIs to be influenced by core substituents. The strong electron-donating character of pyrrolidine substituents results in rather high HOMO and LUMO levels of -5.31 and -3.37 eV when compared with the parental unsubstituted NDI. UHV-STM measurements of a sub-monolayer of the rigid tripodal NDI chromophores spray deposited on Au(111) show that these molecules mainly tend to adsorb flat in a pairwise fashion on the surface and form unordered films. However, the STML experiments also revealed a few molecular clusters, which might consist of upright oriented molecules protruding from the molecular island and show electroluminescence photon spectra with high electroluminescence yields of up to 6×10$^{-3}$. These results demonstrate the promising potential of the NDI tripodal chromophores for the fabrication of molecular devices profiting from optical features of the molecular layer

Wind power energy: interaction of the atmosphere with the environment

The objective of this paper is to sketch, in a general context, influences on construction of wind power plants and problems associated with them when choosing the right area for their construction

Wind speed energy: speed and unit power wind maps

Power levels of new wind power units are increasing and their axes reach heights about 100m over ground with the rotor diameters about 90m for 4MW unit. It is very necessary to know long term average values of the wind speed and others stream relations in these overground levels of atmosphere as well. This article deals with creations of air streams maps and their application in practice