Adsorption of caffeic acid on titanium dioxide: A spectroscopic study

Caffeic acid is an ortho-phenol found in vegetable tissues presenting important properties such as carcinogenesis inhibitor, anti-oxidant, anti-viral, anti-inflammatory and anti-rheumatic actions. It was observed that caffeic acid was not degraded in daylight during the adsorption on TiO2 at pH 4.8. The adsorption fit very well to a Brunauer-Emmett-Teller isotherm equation with a monolayer coverage of 68.15 mg(CA) g(TiO2)(-1) and saturation coverage of 195.4 mg(CA) g(TiO2)(-1). A strong adsorption of caffeic acid was verified on TiO2 for the dry solid obtained from the mixture. The Raman and IR spectroscopies revealed that the adsorption should occur through the interaction of the diphenol oxygens with contribution of CC double bond of the acrylic group, however, the carboxylic acid group did not have participation in the adsorption. (C) 2012 Elsevier B.V. All rights reserved.

Efeito da adição de lantânio em catalisadores de Ni/ZrO2 aplicados na reação de reforma a vapor de etanol

The catalytic performance of Ni/ZrO2 catalysts loaded with different lanthanum content for steam reforming of ethanol was investigated. Catalysts were characterized by BET surface area, X-ray diffraction, UV-vis spectroscopy, temperature programmed reduction, and X-ray absorption fine structure techniques. Results showed that lanthanum addition led to an increase in the degree of reduction of both NiO and nickel surface species interacting with the support, due to the higher dispersion effect. The best catalytic performance at 450 ºC was found for the Ni/12LZ catalyst, which exhibited an effluent gaseous mixture with the highest H2 yield.

The influence of both urea and 2,2,2

The influence of external agents on proteins function and structure is essential to elucidate the unfolding pathways and self-assemble properties. The knowledge of the protein amyloid fibril formation process is important due to the fields that this subjected is related, in particular for the neurodegenerative disorders. In the present work we studied the influence of both urea and 2,2,2-Trifluoroethanol (TFE) and temperature on the structure and proteinprotein interactions of Bovine Serum Albumin (BSA), by means of UV-Vis spectroscopy, static fluorescence and small angle X-ray scattering technique. The experiments were performed in samples composed by 10 and 3 mg/ml of BSA at pH 5.8, near the protein pI. First, Thioflavin-T fluorescence measurements indicated that urea, in the absence of TFE, was able to increase the amyloid fibril formation of BSA at 45oC and increasing the urea concentration the rate of amyloid fibril formation also increases. Concerning the presence of TFE, SAXS data suggest that BSA tridimensional structure is not altered by the presence of TFE 5% and 10% v/v in all studied protein concentrations. Interestingly, the presence of TFE on the urea-containing BSA also increases the rate of amyloid fibril formation, as compared to the TFE-free system, indicating that TFE can catalyze the amyloid-fibril formation. The presence of TFE 20% v/v, however, induces the formation of aggregates, but at this time we were not able to infer if such aggregates are amyloidlike or amorphous. Taking together, the results give support to infer that BSA can for fibrils in the presence of urea at 45oC and TFE can act as a stabilizer or as a denaturant agent for BSA.

Sviluppo di metodi innovativi per la sintesi di nanoparticelle di interesse industriale

Among various nanoparticles, noble metal nanoparticles have attracted considerable attention due to their optical, catalytic and conducting properties. This work has been focused on the development of an innovative method of synthesis for the preparation of metal nanosuspensions of Au, Ag, Cu, in order to achieve stable sols, showing suitable features to allow an industrial scale up of the processes. The research was developed in collaboration with a company interested in the large scale production of the studied nanosuspensions. In order to develop a commercial process, high solid concentration, long time colloidal stability and particle size control, are required. Two synthesis routes, differing by the used solvents, have been implemented: polyol based and water based synthesis. In order to achieve a process intensification the microwave heating has been applied. As a result, colloidal nanosuspensions with suitable dimensions, good optical properties, very high solid content and good stability, have been synthesized by simple and environmental friendly methods. Particularly, due to some interesting results an optimized synthesis process has been patented. Both water and polyol based synthesis, developed in the presence of a reducing agent and of a chelating polymer, allowed to obtain particle size-control and colloidal stability by tuning the different parameters. Furthermore, it has been verified that microwave device, due to its rapid and homogeneous heating, provides some advantages over conventional method. In order to optimize the final suspensions properties, for each synthesis it has been studied the effect of different parameters (temperature, time, precursors concentrations, etc) and throughout a specific optimization action a right control on nucleation and growth processes has been achieved. The achieved nanoparticles were confirmed by XRD analysis to be the desired metal phases, even at the lowest synthesis temperatures. The particles showed a diameter, measured by STEM and dynamic light scattering technique (DLS), ranging from 10 to 60 nm. Surface plasmon resonance (SPR) was monitored by UV-VIS spectroscopy confirming its dependence by nanoparticles size and shape. Moreover the reaction yield has been assessed by ICP analysis performed on the unreacted metal cations. Finally, thermal conductivity and antibacterial activity characterizations of copper and silver sols respectively are now ongoing in order to check their application as nanofluid in heat transfer processes and as antibacterial agent.

Von zwei- zu dreidimensionalen Graphitausschnitten

Zusammenfassung: 'Von zwei- zu dreidimensionalen Graphitausschnitten'Dissertation Florian Dötz Die vorliegende Arbeit zeichnet den synthetischen Weg von zwei- zu dreidimensionalen Graphitausschnitten nach und thematisiert insbesondere die Schnittstelle dieser beiden Bereiche, die durch den Übergang von planaren Systemen zu räumlichen Strukturen verkörpert wird und daher die Darstellung nicht-planarer polycyclischer aromatischer Kohlenwasserstoffe (PAH) vorsieht. Diese Zielsetzung mündet in einer dreiteiligen Gliederung der angefertigten Dissertation und sieht im ersten Teil die Synthese planarer Graphitsegmente durch oxidative Cyclodehydrierung entsprechender Oligophenylvorläufer mit Eisen(III)chlorid vor, gefolgt von der Darstellung nicht-planarer PAHs mit denselben oxidativen Methoden sowie der Präparation und Charakterisierung dreidimensionaler, supramolekularer PAH-Aggregate.Der erste Abschnitt beschreibt die Synthese von kleineren PAHs als Modellverbindung für größere Systeme und ihre UV-spektroskopische Charakterisierung. Daran anknüpfend wird die Synthese mehrerer heteroatomsubstituierter Derivate des Hexa-peri-hexabenzocoronens (HBC) vorgestellt und ihre flüssigkristallinen Eigenschaften eingehend untersucht. Dabei wurde mit der oxidativen Cyclodehydrierung geeigneter Vorläufer auf Einkristalloberflächen ein neuer Weg zur Synthese dieser Verbindungen etabliert.Im Zentrum des zweiten Teils dieser Arbeit stand die Induktion von Nichtplanarität in ausgedehnten PAHs mit den im ersten Abschnitt entwickelten Synthesekonzepten. Hier konnte mit der erfolgreichen Darstellung eines 18fach methoxysubstituierten HBC-Derivats eine erstaunliche Krümmung des aromatischen Systems erreicht werden, wie durch Kristallstrukturanalyse gezeigt wurde. Anhand mehrerer Beispiele wurde ebenso die Leistungsfähigkeit der verwendeten Cyclodehydrierungsmethode verdeutlicht, da viele Vorläufermoleküle gegenüber den Reaktionsbedingungen nicht inert sind.Der letzte Teil dieser Arbeit beschreibt schließlich die Präparation und Charakterisierung dreidimensionaler, supramolekularer PAH-Aggregate auf der Basis von HBC-Amiden, deren Eigenschaften sich durch eine sorgfältige Wahl der jeweiligen Monomerbausteine manipulieren lassen. Bei Verwendung von chiralen Monomeren wird hier die Expression von supramolekularer Chiralität erreicht und durch spektroskopische und chiroptische Methoden belegt.

Studio di metodi di preparazione e caratterizzazione di nanostrutture per la funzionalizzazione di materiali ceramici

This thesis was carried out in the context of a co-tutoring program between Centro Ceramico Bologna (Italy) and Instituto di Tecnologia Ceramica, Castellón de la Plana (Spain). The subject of the thesis is the synthesis of silver nanoparticles and at their likely decorative application in the productive process of porcelain ceramic tiles. Silver nanoparticles were chosen as a case study, because metal nanoparticles are thermally stable, and they have non-linear optical properties when nano-structured, and therefore they develop saturated colours. The nanoparticles were synthesized by chemical reduction in aqueous solution, a method chosen because of its reduced working steps and energy costs. Besides such a synthesis method uses non-expensive and non-toxic raw material. By adopting this synthesis technique, it was also possible to control the dimension and the final shape of the nanoparticles. Several syntheses were carried out during the research work, modifying the molecular weight of the reducing agent and/or the firing temperature, in order to evaluate the influence such parameters have on the Ag-nanoparticles formation. The syntheses were monitored with the use of UV-Vis spectroscopy and the average dimension as well as the morphology of the nanoparticles was analysed by SEM. From the spectroscopic data obtained from each synthesis, a kinetic study was completed, relating the progress of the reaction to the two variables (ie temperature and molecular weight of the reducing agent). The aim was finding equations that allow the establishing of a relationship between the operating conditions during the synthesis and the characteristics of the final product. The next step was finding the best method of synthesis for the decorative application. For such a purpose the amount of nanoparticles, their average particle size, the shape and the agglomeration are considered. An aqueous suspension containing the nanoparticles is then sprayed over the fired ceramic tiles and they are subsequently thermally treated in conditions similar to the industrial one. The colorimetric parameters of the obtained ceramic tiles were studied and the method proved successful, giving the ceramic tiles stable and intense colours.

Design, synthesis and photochemical studies of stilbenoid dendrimers

Stilbenoid dendrimers with stilbene in the periphery and stilbene in periphery as well as core were synthesized by convergent approach except 2nd generation dendrimer with stilbene in the periphery as well as in core (D-5). All dendrimers were characterized by standard techniques such as 1H NMR, 13C NMR, MS and IR spectroscopy. The MALDI-TOF technique proved to be very helpful in the identification of the 2nd generation dendrimer (D-5) with a mass of 3231 a.m.u. The dendrimers were designed in such a way that an intramolecular photochemical CC bond formation was favored. As two stilbene units of the same molecule were close enough so they preferred an intramolecular cyclic process except for zero generation dendrimers. Apart from the cycloaddition, some E/Z isomerization and oligomer formation was also observed on irradiation. These processes were observed by 1H NMR and MALDI-TOF MS. The photochemical behavior was also studied by UV absorption spectroscopy. Irradiating by monochromatic light led to an initial E/Z isomerization and by prolonged irradiation, an irreversible cyclic structure was formed. The choice of the wavelength of incident light is very important as irradiation at 320 nm leads to a reversible E/Z isomerization and a non-reversible cyclobutane formation, but irradiation at 340 nm favors the one-way process E Z. The [2+2] cycloaddition of molecule Tm2De was also studied by irradiating thin films on a quartz surface. An AFM image was taken before irradiation, after 3 sec irradiation and after long irradiation (1 hour). AFM studies show that a short irradiation leads to a cyclic structure as formation of hills of about 20-30 nm on the surface. A prolonged irradiation leads to a CC cross linking which can be monitored on AFM images as disappearance of hills. The roughness goes back to an almost smooth surface. These results prove a very complex material transport, which accompanies the reaction in the surface region.

Synthese und Charakterisierung photoschaltbarer Gelbildner

Zusammenfassung Um photoschaltbare Gelbildner zu synthetisieren wurde auf bereits bekannte Gelbildner zurückgegriffen und eine Azobenzolgruppe, als photoschaltbare Einheit eingebaut. Die Modifizierung der Alkylsemicarbazide führte zu 7 Azosemicarbaziden (36-42), die alle gelbildende Eigenschaften haben. Die Gele des Alkylsemicarbazids 1 und der Azosemicarbazide 37 und 38 erwiesen sich als die stabilsten, weshalb an ihnen die meisten Untersuchungen durchgeführt wurden. Ihre Struktur ist in Abbildung 1 noch einmal aufgeführt. Die Alkylsemicarbazide vergelen Toluol, 1,2-Dichlorbenzol, Decalin, Tetralin und Cyclohexan. Die minimalen Gelbildnerkonzentration geht dabei von ~0,5 Gew.% für Toluol bis ~10 Gew.% für Tetralin und Cyclohexan. Die Azosemicarbazide 36-40 vergelen Toluol und Tetralin mit ~10 Gew.%, 1,2-Dichlorbenzol und Decalin mit ~4-7 Gew.Durch den Vergleich verschiedener Kristallstrukturen (von 1, 5, 19 und 43) und einer Röntgenkleinwinkelmessung eines Gels wurden zwei mögliche Kristallstrukturen für 37 vorgestellt. Die Tatsache, dass die IR-Spektren aller Semicarbazide im Bulk und als Gel sehr ähnliche Absorptionsbanden im Bereich der N-H-Schwingungen besitzen, zeigt, dass das vorgestellt Wasserstoffbrückenmotiv (Kapitel 4.1, Schema 4.1) für alle Semicarbazide nahezu gleich ist. Des Weiteren konnte ein Zusammenhang von der minimalen Gelbildner-konzentration, dem Schmelzpunkt und der Struktur des Gelnetz-werks gefunden werden. Je feiner das Netzwerk und damit je größer die Oberfläche, desto niedriger die minimale Gelbildnerkonzentration und desto niedriger der Schmelzpunkt der Gele. Gele mit Decalin fallen dabei durch eine andere Morphologie und besonders hohe Schmelzpunkte auf (Abbildung 2). Die Photoschaltbarkeit wurde im Gel mit organischen Lösungsmitteln und mit den Flüssigkristallmischungen durch UV/Vis-Messungen, Polarisationsmikroskopie, sowie durch die Bestimmung der Schaltzeiten und der Schwellspannung für LC II-Gele nachgewiesen. Erste dielektrische Messungen an einem LC II-Gel zeigen, dass die Goldstone-Mode im Gel unterdrück wird. Diese Ergebnisse sollen mit weiteren Untersuchungen untermauert werden.

Spectroscopic studies on Cyclodextrin and Metal Organic Framework based potential nanovectors for delivery of Anticancer and Antiviral drugs

The aim of this work is to contribute to the development of new multifunctional nanocarriers for improved encapsulation and delivery of anticancer and antiviral drugs. The work focused on water soluble and biocompatible oligosaccharides, the cyclodextrins (CyDs), and a new family of nanostructured, biodegradable carrier materials made of porous metal-organic frameworks (nanoMOFs). The drugs of choice were the anticancer doxorubicin (DOX), azidothymidine (AZT) and its phosphate derivatives and artemisinin (ART). DOX possesses a pharmacological drawback due to its self-aggregation tendency in water. The non covalent binding of DOX to a series of CyD derivatives, such as g-CyD, an epichlorohydrin crosslinked b-CyD polymer (pb-CyD) and a citric acid crosslinked g-CyD polymer (pg-CyD) was studied by UV visible absorption, circular dichroism and fluorescence. Multivariate global analysis of multiwavelength data from spectroscopic titrations allowed identification and characterization of the stable complexes. pg-CyD proved to be the best carrier showing both high association constants and ability to monomerize DOX. AZT is an important antiretroviral drug. The active form is AZT-triphosphate (AZT-TP), formed in metabolic paths of low efficiency. Direct administration of AZT-TP is limited by its poor stability in biological media. So the development of suitable carriers is highly important. In this context we studied the binding of some phosphorilated derivatives to nanoMOFs by spectroscopic methods. The results obtained with iron(III)-trimesate nanoMOFs allowed to prove that the binding of these drugs mainly occurs by strong iono-covalent bonds to iron(III) centers. On the basis of these and other results obtained in partner laboratories, it was possible to propose this highly versatile and “green” carrier system for delivery of phosphorylated nucleoside analogues. The interaction of DOX with nanoMOFs was also studied. Finally the binding of the antimalarial drug, artemisinin (ART) with two cyclodextrin-based carriers,the pb-CyD and a light responsive bis(b-CyD) host, was also studied.

Electrostatically self-assembled nanoparticles based on biomolecules

In this work, two different systems were investigated to develop fundamental understanding of the self-assembly behavior of polyelectrolytes and small organic counterions with a certain geometry. Complexes formed were characterized by light scattering in solution, as well as UV-Vis spectroscopy, analytical ultracentrifugation, gel electrophoresis, zeta potential and IR spectroscopy. The morphologies of the aggregates were observed by AFM in dried state on surface. The charge ratio, the valence and the structure of the counterion were shown to represent key parameters in the complexation. The influence of polyelectrolyte type and molecular weights was also determined for the structure formed.rnrnOne system was mainly focused on the association of double-strand DNA with non-intercalating divalent and tetravalent organic counterions. The other model system involved linear NaPSS and oligolysines. In addition, various influences on the morphology of the charged self-assembly complexes in AFM studies were discussed. It was shown that electrostatic self-assembly of DNA and non-intercalating counterions as well as of a linear synthetic polyelectrolyte with oligolysine counterions that can build mutual hydrogen bonds can yield supramolecular aggregates of a defined size. Various morphologies (flower-like, rod-like, toroidal and spherical) of the assemblies were obtained for different combinations of polyelectrolyte and counterions. Results presented in this work are of importance for the fundamental understanding of the association behavior of various polyelectrolytes and organic counterions. The selection of biopolymers for the study may give an opportunity to transfer the basic research results into biological applications, such as gene therapy or drug delivery.rn

Polimeri tiofenici funzionali e loro applicazioni nel fotovoltaico

Recentemente, sempre più attenzione è stata rivolta all' utilizzo di coloranti organici come assorbitori di luce per la preparazione di strati fotoattivi in celle solari organiche (OPV). I coloranti organici presentano un'elevata abilità nella cattura della luce solare grazie all'elevato coefficiente di estinzione molare e buone proprietà fotofisiche. Per questi motivi sono eccellenti candidati per l'incremento della conversione fotoelettrica in OPV. In questa tesi viene descritta una nuova strategia per l'incorporazione di derivati porfirinici in catena laterale a copolimeri tiofenici. Gli studi svolti hanno dimostrato che poli(3-bromoesil)tiofene può essere variamente funzionalizzato con idrossitetrafenilporfirina (TPPOH), per l'ottenimento di copolimeri utilizzabili come materiali p-donatori nella realizzazione di OPV. I copolimeri poli[3-(6-bromoesil)tiofene-co-(3-[5-(4-fenossi)-10,15,20-trifenilporfirinil]esil tiofene] P[T6Br-co-T6TPP] contenenti differenti quantità di porfirina, sono stati sintetizzati sia con metodi non regiospecifici che regiospecifici, con lo scopo di confrontarene le proprietà e di verificare se la strutture macromolecolare che presenta una regiochimica di sostituzione sempre uguale, promuove o meno il trasporto della carica elettrica, migliorando di conseguenza l'efficienza. E' stato inoltre effettuato un ulteriore confronto tra questi derivati e derivati simili P[T6H-co-T6TPP] che non contengono l'atomo di bromo in catena laterale con lo scopo di verificare se l'assenza del gruppo reattivo, migliora o meno la stabilità termica e chimica dei film polimerici, agendo favorevolmete sulle performance dei dispositivi fotovoltaici. Tutti i copolimeri sono stati caratterizzati con differenti tecniche: spettroscopia NMR, FT-IR e UV-Vis, analisi termiche DSC e TGA, e GPC. Le celle solari Bulk Heterojunction, preparate utilizzando PCBM come materiale elettron-accettore e i copolimeri come materilai elettron-donatori, sono state testate utilizzando un multimetro Keithley e il Solar Simulator.

Silk Fibroin: a biopolymer platform for innovative pharmaceutical formulation and biomedical devices.

The protein silk fibroin (SF) from the silkworm Bombyx mori is a FDA-approved biomaterial used over centuries as sutures wire. Importantly, several evidences highlighted the potential of silk biomaterials obtained by using so-called regenerated silk fibroin (RSF) in biomedicine, tissue engineering and drug delivery. Indeed, by a water-based protocol, it is possible to obtain protein water-solution, by extraction and purification of fibroin from silk fibres. Notably, RSF can be processed in a variety of biomaterials forms used in biomedical and technological fields, displaying remarkable properties such as biocompatibility, controllable biodegradability, optical transparency, mechanical robustness. Moreover, RSF biomaterials can be doped and/or chemical functionalized with drugs, optically active molecules, growth factors and/or chemicals In this view, activities of my PhD research program were focused to standardize the process of extraction and purification of protein to get the best physical and chemical characteristics. The analysis of the chemo-physical properties of the fibroin involved both the RSF water-solution and the protein processed in film. Chemo-physical properties have been studied through: vibrational (FT-IR and Raman-FT) and optical (absorption and emission UV-VIS) spectroscopy, nuclear magnetic resonance (1H and 13C NMR), thermal analysis and thermo-gravimetric scan (DSC and TGA). In the last year of my PhD, activities were focused to study and define innovative methods of functionalization of the silk fibroin solution and films. Indeed, research program was the application of different methods of manufacturing approaches of the films of fibroin without the use of harsh treatments and organic solvents. New approaches to doping and chemical functionalization of the silk fibroin were studied. Two different methods have been identified: 1) biodoping that consists in the doping of fibroin with optically active molecules through the addition of fluorescent molecules in the standard diet used for the breeding of silkworms; 2) chemical functionalization via silylation.

Studies of degradation of organic solar cell materials using electrical scanning probe microscopy

Intense research is being done in the field of organic photovoltaics in order to synthesize low band-gap organic molecules. These molecules are electron donors which feature in combination with acceptor molecules, typically fullerene derivarntives, forming an active blend. This active blend has phase separated bicontinuous morphology on a nanometer scale. The highest recorded power conversionrnefficiencies for such cells have been 10.6%. Organic semiconductors differ from inorganic ones due to the presence of tightly bonded excitons (electron-hole pairs)resulting from their low dielectric constant (εr ≈2-4). An additional driving force is required to separate such Frenkel excitons since their binding energy (0.3-1 eV) is too large to be dissociated by an electric field alone. This additional driving force arises from the energy difference between the lowest unoccupied molecular orbital (LUMO) of the donor and the acceptor materials. Moreover, the efficiency of the cells also depends on the difference between the highest occupied molecular orbital (HOMO) of the donor and LUMO of the acceptor. Therefore, a precise control and estimation of these energy levels are required. Furthermore any external influences that change the energy levels will cause a degradation of the power conversion efficiency of organic solar cell materials. In particular, the role of photo-induced degradation on the morphology and electrical performance is a major contribution to degradation and needs to be understood on a nanometer scale. Scanning Probe Microscopy (SPM) offers the resolution to image the nanometer scale bicontinuous morphology. In addition SPM can be operated to measure the local contact potential difference (CPD) of materials from which energy levels in the materials can be derived. Thus SPM is an unique method for the characterization of surface morphology, potential changes and conductivity changes under operating conditions. In the present work, I describe investigations of organic photovoltaic materials upon photo-oxidation which is one of the major causes of degradation of these solar cell materials. SPM, Nuclear Magnetic Resonance (NMR) and UV-Vis spectroscopy studies allowed me to identify the chemical reactions occurring inside the active layer upon photo-oxidation. From the measured data, it was possible to deduce the energy levels and explain the various shifts which gave a better understanding of the physics of the device. In addition, I was able to quantify the degradation by correlating the local changes in the CPD and conductivity to the device characteristics, i.e., open circuit voltage and short circuit current. Furthermore, time-resolved electrostatic force microscopy (tr-EFM) allowed us to probe dynamic processes like the charging rate of the individual donor and acceptor domains within the active blend. Upon photo-oxidation, it was observed, that the acceptor molecules got oxidized first preventing the donor polymer from degrading. Work functions of electrodes can be tailored by modifying the interface with monomolecular thin layers of molecules which are made by a chemical reaction in liquids. These modifications in the work function are particularly attractive for opto-electronic devices whose performance depends on the band alignment between the electrodes and the active material. In order to measure the shift in work function on a nanometer scale, I used KPFM in situ, which means in liquids, to follow changes in the work function of Au upon hexadecanethiol adsorption from decane. All the above investigations give us a better understanding of the photo-degradation processes of the active material at the nanoscale. Also, a method to compare various new materials used for organic solar cells for stability is proposed which eliminates the requirement to make fully functional devices saving time and additional engineering efforts.

Hydrogels for DNA isolation from blood

This dissertation describes the synthesis of surface attached hydrogel biomaterials, characterization of their properties, evaluation of structuring concepts and the investigation of these materials in the isolation of DNA from human whole blood. Photosensitive hydrogel precursor materials on the basis of hydroxyethylmethacrylate (HEMA) were synthesized by free radical polymerization. In order to obtain surface bound hydrogel films, the precursors were deposited on a suitable substrate and subsequently irradatiated with UV - light to accomplish the formation of crosslinks in the film and create surface attachment. The composition of the polymerization precursor materials was determined by comprehensive NMR and GPC studies, revealing the copolymerizationrnbehaviour of the used monomers - HEMA derivatives and the photocrosslinkerrnMABP - and their respective distribution in the hydrogel precursors. The degree of crosslinking of the hydrogels was characterized with UV/vis spectroscopy. Stress-strain measurements were conducted in order to investigate the mechanical properties of the biomaterials. Moreover, the swelling process and biomolecule adsorption properties of the hydrogels were investigated with SPR/OW spectroscopy. For this, the deposition and binding of the hydrogels on gold or SiO2 surfaces was facilitated with photocrosslinkable adhesion promotors. The produced hydrogels were mechanically rigid and stablernunder the conditions of PCR and blood lysis. Furthermore, strategies towards the increase of hydrogel surface structure and porosity with porosigens, 2D laser interference lithography and photocleavable blockcopolymers were investigated. At last, a combinatorial strategy was used for the determination of the usefulness of hydrogels for the isolation from DNA from blood. A series of functionalized hydrogel precursors were synthesized, transferred to the surface inside a PCR tube and subsequently screened in regard to DNA adsorption properties with Taqman quantitative PCR. This approach yielded a promising candidate for a functional PCR tube coating that would allow the entire DNA isolation procedure being carried out in a single reaction container.rnThereforce, the practical application of such macromolecular architectures can be envisioned to improve industrial DNA diagnostic processes.

Interactions of gold nanoparticles with polymeric membranes

This thesis focuses on the interactions of nanoparticles with artificial membranes. The synthesis of the block copolymer poly(dimethylsiloxane)-block-poly(2-methyloxazoline) (PDMS-b-PMOXA) is described, as well as the formation of polymersomes in water. These polymersomes act as minimal cell models, consisting of an artificial bilayer membrane only, allowing the study of the interactions between nanoparticles and polymeric membranes. Both spherical and rod-shaped gold nanoparticles (AuNPs) were used in this study and they were characterized using light scattering (PCS), transmission electron microscopy (TEM), UV/Vis spectroscopy, and polarization anisotropy measurements. The polymer grafting on the spherical cores is asymmetric (shell asphericity) but is parallel to the inherent, due to polycrystallinity, core anisotropy, resulting in a characteristic scattering of the AuNPs in PCS.rnInteractions of polymersomes and AuNPs were investigated by PCS, cryo-TEM and UV/Vis. Three possible scenarios upon mixing of polymersomes and AuNPs can be distinguished by using only PCS: (i) no interactions between particles and vesicles, (ii) attachment of the particles to the outer side of the vesicles (decoration), and (iii) uptake of particles into the vesicles. It is shown that all three scenarios are possible, solely depending on the particle’s surface functionalization. In addition, it was revealed that the AuNPs need to be attached to the inner side of the membrane instead of diffusing freely within the vesicle. The present experimental findings essentially help with the understanding of the interactions of nanoparticles with membranes and show that the process of endocytosis can be attributed to physical processes only. rn