In this paper SAM (self-assembled monolayers) is used to passivate cobalt microbumps for 3D-stacking of Si chips. The SAM deposition process is optimized, using input from characterization techniques such as water contact angle measurement, ATR, AFM and XPS analysis in order to form a monolayer of Thiols-SAM on cobalt microbumps. A 3D stacked Si chips test vehicle was used to demonstrate the effectiveness of the SAM coating on cobalt bumps by measuring the electrical continuity of daisy chains.

Cell adhesion is the first step of cell response to materials and the extracellular matrix (ECM), and is essential to all cell behaviours such as cell proliferation, differentiation, migration and apoptosis for anchor-dependent cells. Therefore, studies of cell attachment have important implications to control and study cell behaviours. During many developed techniques for cell attachment, the manipulation of surface chemistry is a very important method to control initial cell attachment. To control cell adhesion on a two-dimensional surface is a simple model to study cell behaviours, and is a fundamental topic for cell biology, tissue engineering, and the development of biosensors. From the engineering point of view, the preparation of a material with controllable surface chemistry can help studies of cell behaviours and help scientists understand how surface features and chemistry influence cell behaviours. During the fabrication, the challenge is to create a surface with heterogeneous surface properties in the micro scale and subsequently to guide cell initial adhesion. In order to control cell adhesion in a spatial and temporal manner, a photochemical method to control surface chemistry was employed to control the surface property for cell adhesion in this project. Two photocleavable derivatives of the nitrobenzyl group were tried on two types of surfaces: a model self-assembled monolayer (SAM) with alkanethiol-gold surface and biodegradable chitosan. Reactive functional groups on two different surfaces can be inactivated by covalent binding with these photocleavable molecules, and light can be further introduced into the system as a stimulus to recover their reactivity. By simply applying a photomask with diffe

Metal and metal oxides are widely used in industry, and to optimize their performance their surfaces are commonly functionalized by the formation of thin films. Self-assembled monolayers (SAMs) are deposited on metals or metal oxides either from solution or by gas deposition. Thiols with polar terminal groups are utilized for creating the responsive surfaces which can interact electrostatically with other adsorbates. Surface charge effects wetting and adhesion, and many other surface properties. Polar terminal groups in thiols could be used to modify these factors. Mixed SAMs can provide more flexible surfaces, and could change the resulting surface properties under the influence of factors such as pH, temperature, and photo-illumination. Therefore, in order to control these phenomena by mixed polar-terminated thiols, it is necessary to understand the composition and conformation of the mixed SAMs and their response to these factors. In this work, mixtures of thiols with carboxylic and amino terminal groups were studied. Carboxylic and amino terminal groups of thiol interact with each other via hydrogen bonding in solution and form a complex. Complexes adsorb to the surface in non-conventional orientations. Unmixed SAMs from each type, either carboxylic terminated thiols or amino terminated thiols are in standing up orientation while SAMs from complexes are in an axially in-plane orientation. Selenol is an alternative to replace thiols for particular applications such as contact with biological matter which has a better compatibility with selenol than sulfur. However, the    Se-C bond is weaker than the S-C bond which limits the application of selenol. Understanding the selenol adsorption mechanism on gold surfaces could shed some light on Se-C cleavage and so is investigated in this work. Se-C cleavage happens in the low coverage areas on the step since atoms at steps have lower coordination making them more reactive than atoms on the terraces.  Another area where the self-assembly of molecules is of importance is for dye sensitized solar cells, which are based on the adsorption of the dye onto metal oxides surfaces such as TiO2.The interface between the SAM of dye and the substrate is an important factor to consider when designing dyes and surfaces in dye sensitized solar cells (DSSCs). The quality of the self-assembled monolayers of the dye on the TiO2 surface has a critical influence on the efficiency of the DSSCs.  Creation of just a monolayer of dye on the surface could lead to an efficient current of photo-excited electrons to the TiO2 and degeneration of the dye by redox. This work, T-PAC dye showed island growth with some ad-layer that is not in contact with the surface, whereas the MP13 dye adsorption is laminar growth.  Cuprite (Cu2O) is the initial and most common corrosion product for copper under atmospheric conditions. Copper could be a good replacement for noble metal as catalysts for methanol dehydrogenation. Knowledge about the structure of Cu2O(100) and Cu2O(111) surfaces could be used to obtain a deeper understanding of methanol dehydrogenation mechanisms with respect to adsorption sites on the surfaces. In this work, a detailed study was done of Cu2O(100) surface which revealed the possible surface structures as the result of different preparation conditions. Studies of the structure of Cu2O(100) and Cu2O(111) surfaces show that Cu2O(100) has a comparatively stable surface and reduces surface reactivity. As a consequence, dehydrogenation of methanol is more efficient on the Cu2O(111) surface. The hydrogen produced from methanol dehydrogenation is stored in oxygen adatom sites on both surfaces. / <p>QC 20161107</p>

Cell adhesion is the first step of cell response to materials and the extracellular matrix (ECM), and is essential to all cell behaviours such as cell proliferation, differentiation, migration and apoptosis for anchor-dependent cells. Therefore, studies of cell attachment have important implications to control and study cell behaviours. During many developed techniques for cell attachment, the manipulation of surface chemistry is a very important method to control initial cell attachment. To control cell adhesion on a two-dimensional surface is a simple model to study cell behaviours, and is a fundamental topic for cell biology, tissue engineering, and the development of biosensors. From the engineering point of view, the preparation of a material with controllable surface chemistry can help studies of cell behaviours and help scientists understand how surface features and chemistry influence cell behaviours. During the fabrication, the challenge is to create a surface with heterogeneous surface properties in the micro scale and subsequently to guide cell initial adhesion. In order to control cell adhesion in a spatial and temporal manner, a photochemical method to control surface chemistry was employed to control the surface property for cell adhesion in this project. Two photocleavable derivatives of the nitrobenzyl group were tried on two types of surfaces: a model self-assembled monolayer (SAM) with alkanethiol-gold surface and biodegradable chitosan. Reactive functional groups on two different surfaces can be inactivated by covalent binding with these photocleavable molecules, and light can be further introduced into the system as a stimulus to recover their reactivity. By simply applying a photomask with diffe

Utilizing self-assembled monolayer nanotechnology, micro-electro-mechanical systems (MEMS) and IC technologies, a novel flexural plate-wave (FPW) biosensor is developed in this dissertation for detecting the immunoglobulin-E (IgE) concentration of human serum. The acoustic waves of the proposed FPW devices are launched by the 25-pair inter-digital transducer (IDT) input electrodes and propagated through the 4.82 £gm-thick Si/SiO2/Si3N4/Cr/Au/ZnO floating thin-plate. Since the thickness of such floating thin-plate is much smaller than the designed wavelength of FPW device (80 £gm), most of the propagating wave energy will not be dissipated into outside of thin-plate and the mass sensitivity is very high. To further reduce the insertion loss of the proposed FPW devices, two 3 £gm-thick Al reflection grating electrodes (RGE) are designed beside the input and output IDTs. To implement a FPW-based IgE biosensor, a Cr/Au electrode layer has to be deposited on the backside of the floating thin-plate to serve as a substrate for further coating the cystamine SAM/glutaraldehyde/IgE antibody layers. Once the IgE antigens of human serum are bound to the IgE antibody layer, the small change in the mass of floating thin-plate will result in a shift of center frequency of the testing FPW-based biosensor. Compared to the reference FPW biosensors, the shift of center frequency generated by the testing FPW biosensor under different IgE antigen concentration can be detected by commercial network analyzer or the frequency-shift readout system developed by our collaboration laboratory (VLSI Design Lab. of NSYSU). Compared to commercial enzyme linked immunosorbent assay (ELISA) analyzer (sample volume >25 £gl/well, testing time >60 min, dimension>40 cm ¡Ñ30 cm¡Ñ10 cm), the implemented FPW-based IgE biosensor presents a smaller sample volume (<5 £gl), faster response (<10 min) and smaller size (<9 mm¡Ñ6 mm¡Ñ0.5 mm). In addition, a very low insertion loss (-9.2 dB), a very high mass sensitivity (-6.08¡Ñ109 cm2 g-1) and a very high sensing linearity (99.46 %) of the proposed IgE biosensor can be demonstrated at 6.6 MHz center frequency. This study successfully developed a novel FPW-based allergy biosensor by MEMS technology, which has great potential to be further applied into point-of-care testing (POCT) microsystem.

Studies of biomolecular interactions are of interest for several reasons. Beside basic research, the knowledge gained from such studies is also very valuable in for example drug target identification. Medical care is another area where biomolecules may be used as biomarkers to aid physicians in making correct diagnosis. In addition, the highly specific interactions between antibodies and almost any substance opens up the possibilities to design systems for detection of trace amounts of both biological and non-biological substances within environmental restoration, law enforcement, correctional care, customs service and national security. A biochip, which contains a biologically active material, offers a means of monitoring the molecular interactions in the above applications in a sensitive and specific manner. The biochip is a key component of a biosensor, which also includes components for transforming the interaction events into a human-readable signal. This thesis describes the use of poly(ethylene glycol) (PEG) in biochip design. Two different approaches are presented, the first based on ethylene glycol (EG)-containing alkyl thiol self-assembled monolayers (SAMs) on flat gold and the second on photo-induced graft copolymerisation of PEG-containing methacrylate monomers onto various substrates. The former is a two dimensional system where EG-terminated thiols are mixed with similar thiols presenting tail groups that mimic the explosive substance 2,4,6-trinitrotoluene (TNT). In an immunoassay, the detection limit for TNT was determined to fall in the range 1-10 µg/L. In the second approach, a branched three dimensional biosensor matrix (hydrogel) is proposed. The carboxymethylated (CM) dextran matrix, which is commonly used within the biosensing community, is not always ideal for studies of biointeractions, due to the non-specific binding frequently encountered in work with complex biological solutions and various proteins. To employ PEG, which displays a low non-specific binding of such species, is therefore an interesting option worth investigating. The use of a branched graft polymerised PEG matrix in biosensor applications is novel as compared to previous reports which have focused on linear PEG chains. The latter approach provides, at maximum, one functional group, per surface anchoring point, for immobilisation of sensor elements. Thus, it has the inherited disadvantage that it limits the number of available immobilisation sites. The present PEG matrix contains a large number of functional groups, for immobilisation of sensor elements, per grafting site and offers the potential of improved response upon binding to the analyte as demonstrated in a series of successful sensor experiments. Furthermore, the nature of the process enables easy preparation of matrix patterns and gradients. In a PEG matrix gradient, protein permeability is studied and the capabilities of immobilising proteins are demonstrated. By combining the patterning technique with different monomers in a two-step process, an inert platform, lacking chemical attachment sites, is provided with arrays of spots (with immobilisation capabilities), which are conveniently addressed via microdispensing and used for biosensor purposes. The EG-terminated thiols present another means of generating such inert platforms, a route which is also investigated. To further explore the sensor quality of these spots, the concepts of patterning and gradient formation are combined and studied. / Det är intressant att studera biomolekylära interaktioner av många anledningar. För att kunna bedriva framgångsrik läkemedelsutveckling är det oerhört viktigt att känna till hur olika molekyler samverkar i människokroppen. Inom sjukvården kan biomolekyler användas som biomarkörer, då närvaro av dem eller förändringar av deras koncentrationer är kopplade till sjukdomstillstånd, och därmed hjälper läkaren att ställa rätt diagnos. Dessutom kan de mycket specifika interaktionerna mellan antikroppar och (i princip) valfri substans användas för detektion av spårämnen vid miljösaneringsarbete, gränskontroller, polisarbete, fängelser och arbete med nationell säkerhet. Den här avhandlingen beskriver hur polymeren polyetylenglykol (PEG) kan användas vid design av biochip. Ett biochip är en liten anordning, som kan användas för att detektera specifika molekyler med hjälp av en biologisk interaktion. Traditionellt har PEG använts inom biomaterialsektorn, men återfinns även i hygienartiklar som tvål och tandkräm. Ett annat användningsområde är konservering av bärgade träskepp och i en del litiumjonbatterier ingår PEG som en komponent. Dessutom pågår utveckling av PEG-innehållande skyddsvästar. I det här arbetet används PEG framför allt på grund av sin förmåga att minimera ospecifik inbindning av proteiner, som utgör en stor del av gruppen biomolekyler, till ytor på biochip. Två olika typer av ytbeläggningar, som innehåller den här polymeren, har använts. Den första typen ger mycket tunna (~0.000003 mm), tvådimensionella filmer medan den andra ger en något tjockare (~0.00005 mm), tredimensionell struktur (matris). De tvådimensionella filmerna har använts för att utveckla en sprängämnesdetektor med mycket hög känslighet (detektionsgräns mellan 1-10 ppb). En viktig beståndsdel i detta system är antikroppar riktade mot sprängämnet trinitrotoluen (TNT). Den tredimensionella matrisen är mer generell och kan användas för att studera många olika molekylära interaktioner. Tillverkningsmetoden av matrisen är baserad på belysning med ultraviolett ljus och är därmed lämpad för att skapa mönstrade ytor. Genom att blockera delar av ljusflödet begränsas tillväxten av matrisen till de belysta delarna. På så sätt har bland annat så kallade mikro-arrayer, bestående av mikrometerstora (tusendels millimeter) strukturer i ett regelbundet mönster, tillverkats. Tekniken tillåter även tillverkning av gradienter, där matrisens tjocklek varierar längs med provet, genom att belysa olika delar av provytan olika länge. Genom att undersöka dessa gradienter har information om matrisens genomsläpplighet för proteiner kunnat extraheras. Gradientkonceptet har även kombinerats med mikro-arraytillverkningen och gett möjlighet att studera interaktioner mellan flera olika modellproteiner och deras motsvarande antikroppar i olika tjocka matriser på en och samma yta. Det finns ett stort antal sätt att utnyttja interaktionerna mellan olika molekyler på ett biochip. Ett tilltalande tillvägagångssätt är exempelvis att i en mikro-array binda in olika molekyler som kan fånga kliniskt intressanta biomolekyler, i syfte att skapa en hälsoprofil. Ett sådant biochip skulle ge möjlighet att parallellt detektera eller bestämma koncentrationen av ett stort antal biomolekyler i till exempel en droppe blod. På så sätt kan en diagnos snabbt ställas, kanske till och med utan att patienten behöver uppsöka sjukvården. Den utvecklade PEG-matrisen har god potential att fungera i en sådan applikation.

Molecular self-assembly has recently attracted significant attention for possible application in organic electronic and optoelectronic devices, such as self-assembled monolayer field-effect transistors (SAMFETs) and functional self-assembled integrated circuits. Self-assembly combines the advantages of low temperature solution processability, regio-selective monolayer adsorption and nano-scale control of film thickness. Much progress has been made in improving device performance using self-assembled monolayers (SAMs). However, most SAMFET devices reported to date showed current modulation only with submicrometre channels, with low device yields and poor reproducibility as a result of limited lateral interconnection of the semiconducting layer.In an attempt to address these issues, this thesis presents an investigation of the synthesis and properties of conjugated SAM molecules for use as the charge transporting layer in SAMFETs. Chapter 1 gives a comprehensive introduction to SAM-based surface systems, organic semiconductors and their use in OFETs and SAMFETs. Chapter 2 discusses attempts to design and synthesise p-type conjugated molecules capable of self-assembly on oxide surfaces based on a phenylene-bithiophene semiconducting core. The optical and electrochemical properties, as well as the thermal behaviour of these molecules are studied in detail. This theme is carried over to Chapter 3, which describes the synthesis, chemical and physical characterisation of two families of n-type SAM molecules. These molecules consist of NTCDI cores with hexyl or cyclohexyl chains as end-capping groups. Incorporation of a selection of materials as the active layer in OFETs or SAMFETs to evaluate the charge transport is demonstrated in Chapter 4. Monolayer films based on p-type monochlorosilane-terminated SAM molecules are made using the solution assembly technique and characterised by contact angle and AFM. OFETs made from DH-PTTP by both thermal evaporation and spin coating show high mobilities comparable to the best values reported in the literature. Top-contact SAMFETs show a hole mobility of 1.1 × 10-3 cm2V-1s-1 in air, consistent with those of solution processed DH-PTTP based OFETs. Finally, an overview of the project and some suggestions for future work are presented in Chapter 5.

Atmospheric corrosion indoors is of great practical importance for the degradation of metals, for example in electronics, military equipment, and cultural heritage items. It involves a wide range of chemical, electrochemical, and physical processes occurring in gas, liquid, and solid phases, and at the interfaces between them. Hence, a molecular understanding of the fundamental interactions during atmospheric corrosion is of utmost importance. Copper is one of the most used metals in electrical contacts, power generators, heat exchangers, etc. and is prone to indoor atmospheric corrosion. Although corrosion and oxidation of copper in the presence of corrosion stimulators is thermodynamically inevitable, there are ways to reduce the kinetics of corrosion and oxidation reactions. Self assembled monolayers (SAMs) of organic molecules, when adsorbed on copper surfaces, have proven to be efficient barriers against copper corrosion. However, understanding at the molecular level of the initial stages of corrosion of SAM covered copper in atmospheric corrosion conditions is lacking. The main reason is the inability of the conventional analytical methods to detect and characterize very thin corrosion products formed during the initial stages (from seconds to days) of atmospheric corrosion of SAM covered copper. To overcome this situation a highly surface sensitive technique, vibrational sum frequency spectroscopy (VSFS), has been utilized in situ and ex situ in this thesis to detect and follow the oxidation of alkanethiol SAM covered copper in dry air as well as to assess the conformational changes of SAM molecules during oxidation.  A very sensitive gravimetric method, quartz crystal microbalance with dissipation monitoring (QCM-D), and a highly sensitive and versatile optical technique, nanoplasmonic sensing (NPS), were combined in situ with VSFS to quantify this very slow oxidation process. This combination allowed the heterogeneity of the oxidation process as well as the mass and the rigidity of the corrosion products to be detected simultaneously. To address indoor atmospheric corrosion conditions where carboxylic acids play an important role we next studied the interaction between SAM covered copper and humidified air, to which formic acid was added. The in situ identification of the corrosion products and their formation kinetics was done using near surface sensitive infrared reflection/absorption spectroscopy (IRAS), and the effect of hydrocarbon chain length in alkanethiol SAMs on their corrosion protection efficiency was investigated. The effect of the anchoring group in the SAMs on their corrosion protection efficiency was studied for hexaneselenol using -SeH as the anchoring group, and the results were compared with its thiol counterpart, hexanethiol, with -SH as the anchoring group. Complementary in situ and ex situ VSFS measurements were performed to assess the quality of the SAMs before, during, and after exposure. It was shown that the SAMs of alkanethiols greatly inhibited the formation of copper (I) oxide and slowed down the formation of other corrosion products, i.e. copper formate and copper hydroxid. This was due to a selective hindrance of the corrosion stimulators, oxygen, water, and formic acid molecules reaching the copper-SAM interface. The corrosion inhibiting effect increased with the hydrocarbon chain length. The SAMs of hexaneselenols, on the other hand, exhibited an accelerated formation of copper (I) oxide, copper formate and copper hydroxide compared to an unprotected surface as a result of the partial removal of hexaneselenol molecules from the copper surface during prolonged exposure. The experience gained in characterizing and quantifying thin copper oxides was further used to explore the influence of gamma (γ) radiation on copper corrosion in anoxic water. This multi-analytical approach included IRAS, cathodic reduction, confocal Raman microscope, atomic force microscopy, scanning electron microscopy, x-ray photoelectron spectroscopy, and inductively coupled plasma - atomic emission spectroscopy. The results clearly showed that copper dissolution as well as the oxide layer thickness increase with gamma radiation under the exposure conditions. / Atmosfärisk korrosion under inomhusförhållanden är av stor praktisk betydelse på grund av dess inverkan på exempelvis vårt kulturarv i museimiljöer, tillförlitligheten hos elektronik i olika industriella sammanhang, eller militär utrustning förvarad i olika förråd. Den atmosfäriska korrosionen styrs av ett brett spektrum av kemiska, elektrokemiska och fysikaliska processer som äger rum i tre faser: atmosfären, den tunna fuktfilmen på objektytan och den fasta fasen, samt i de bägge fasgränserna mellan de tre faserna. För att kunna hitta motmedel mot korrosionen är det av yttersta vikt att öka den molekylära förståelsen för dessa processer. Koppar är en mycket använd metall i elektriska eller elektroniska komponenter, i värmeväxlare eller VVS-sammanhang, som beslag och i en rad olika dekorer. Metallen korroderar eller oxiderar spontant i många korrosiva miljöer, men det finns ett brett spektrum av metoder för att minska korrosions- eller oxidationshastigheten. Monoskikt av tätpackade självassocierande organiska molekyler (engelska: self assembled monolayers, förkortat SAM) adsorberade på kopparytan har visat sig vara effektiva barriärer för kopparkorrosion. Den molekylära insikten i dessa monoskikts funktionssätt för att minska den atmosfäriska korrosionen är dock ännu rätt så begränsad. Den främsta orsaken är oförmågan hos mer etablerade analytiska metoder att kunna karakterisera de ytterst små mängder av korrosionsprodukter som bildas under den atmosfäriska korrosionens inledande skeenden upp till några dagars exponering. Den extremt ytkänsliga och i korrosionssammanhang fortfarande relativt oprövade analysmetoden summafrekvensspektroskopi (engelska: vibrational sum frequency spectroscopy, förkortat VSFS) har därför använts för att under pågående exponering följa det mycket långsamma oxidationsförlopp som uppstår när koppar, skyddat av något organiskt monoskikt, exponeras för torr luft. VSFS har även kunnat användas för att under pågående oxidation följa strukturella förändringar hos monoskiktet. För att kvantifiera en så långsam oxidationsprocess har även en annan extremt masskänslig metod kunnat kombineras med VSFS, en kvartskristallmikrovåg med s.k. dissipationsövervakning, förkortat QCM-D. Ytterligare en i korrosionssammanhang oprövad men lika masskänslig teknik har kunnat kombineras med VSFS. Den metoden besitter än så länge bara ett engelskt namn, nanoplasmonic sensing (NPS). Kombinationen VSFS–QCM-D–NPS har utnyttjats i en serie unika försök, där inte bara de ytterst långsamma oxidationshastigheterna kunnat mätas upp, utan även andra viktiga faktorer såsom graden av heterogenitet i den bakomliggande oxidationsprocessen. För att närma sig en miljö som kan efterlikna korrosiva inomhusförhållanden har atmosfären i nästa steg befuktats och dessutom har låga halter av myrsyra tillsats. Just tillsatsen av karboxylsyror har visat sig generera korrosionsprodukter med en sammansättning som på koppar och vissa andra metaller efterliknar de som bildas under atmosfärisk korrosion inomhus. Identifiering av korrosionsprodukter och deras tillväxthastighet på koppar, skyddat av olika långa tätpackade kolkedjor med en tiolgrupp i ena ändan som binder till kopparsubstratet, har kunnat ske med infraröd reflektions-absorptionsspektroskopi (IRAS) under in situ-förhållanden. Ju längre kolvätekedjor desto större korrosionsinhibieringsförmåga kunde påvisas. När den på koppar förankrade tiolgruppen ersattes med en selenolgrupp blev korrosionsinhibieringsförmågan sämre. Kompletterande mätningar in situ och ex situ  utfördes med hjälp av VSFS för att undersöka kvaliteten på de tätpackade kolvätekedjorna, varvid kunde påvisas att graden av tätpackning hos kolkedjorna försämrades med ökad exponeringstid. Förutom den allmänna nedbromsningen av korrosionshastigheten på koppar blev sammansättningen av bildade korrosionsprodukter på oskyddat koppar en annan än på  koppar skyddat av tioler. I det förra fallet detekterades korrosionsprodukterna koppar(I)oxid, koppar(II)format och koppar(II)hydroxid, under det att ingen koppar(I)oxid påvisades på skyddat koppar, endast små mängder koppar(II)format och koppar(II)hydroxid kunde detekteras. De adsorberade kolkedjorna tycks hindra de korrosionsstimulerande molekylerna vatten, myrsyra och syrgas från att nå kopparytan lika effektivt. När de tiolförankrade kolvätekedjorna ersattes med selenolförankrade kolvätekedjor desorberades en del kolvätekedjor från kopparsubstratet vid längre exponeringstider. Resultatet blev att mängden korrosionsprodukter nu blev signifikant större än på oskyddat koppar, sannolikt på grund av galvanisk korrosion. Erfarenheterna från detta doktorsarbete vad gäller kvantifiering av små mängder kopparoxider har även utnyttjats för att undersöka inverkan av g-strålning på kopparkorrosion i rent vatten. Härvid användes ett multianalytiskt angreppssätt bestående av IRAS, katodisk reduktion, konfokal Ramanmikroskopi, atomkraftsmikroskopi, svepelektronmikroskopi, fotoelektronspektroskopi, samt analys av utlöst mängd koppar i vattenlösningen med induktivt kopplad plasmaatomemissionsspektroskopi. Resultaten visar tydligt att utlösningen av koppar, liksom det bildade oxidskiktets tjocklek, ökar med g-strålningen under rådande exponeringsförhållanden. / <p>QC 20131206</p>

The work presented on this thesis is focused on studies of the kinetics of electron transfer in bilayer lipid membranes (BLMs). Three different types of BLM were studied: i) tethered, ii) pore suspended (commonly known as ‘black’) and iii) based on the avidin – biotin interaction (these are part of the wider group of polymer cushioned BLMs). In order to produce tethered BLMs (tBLMs) of the best quality possible, self – assembled monolayers (SAMs) of a thiolipid (1,2 dipalmitoyl-sn-glycero-phosphothioethanol (DPPTE)) and of the same thiolipid mixed with L α phosphatidylcholine (EggPC) were characterised and their behaviour compared to that of SAMs of two alkanethiols (1 – heptanethiol and 1 – dodecanethiol). The SAMs that were formed by a mixture of lipids (DPPTE+EggPC) presented better kinetic parameters and were the chosen to produce tBLMs. Tethered BLMs were made by using the SAM described above as the lower leaflet; the second leaflet was deposited by vesicle fusion, the vesicles were made of EggPC. tBLMs are commonly used as model membranes, however in biophysical studies free-standing membranes or ‘black’ lipid membranes are more realistic models of cellular processes. The rates of electron transfer in both types of bilayer lipid membranes are compared. These BLMs were modified using two very important mitochondrial membrane associated molecules – ubiquinone-10 (UQ10) and α-tocopherol (VitE). The studies involved the use three redox couples, Fe(CN)_6^(3-/4-), Ru(NH_3 )_6^(3+/2+) and NAD+/NADH using cyclic voltammetry and electrochemical impedance spectroscopy. The NAD+/NADH couple is of particular interest as it is the key to several important biochemical processes. The last type of BLM that was studied was the BLMs based on the avidin – biotin interaction. Avidin was deposited on a platinum surface by electrodeposition and then vesicles composed of EggPC and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(biotinyl) (sodium salt) (DOPE(B)) are burst by applying +0.7V (vs. Ag/AgCl, KCl 3.5M), leading to the formation of a supported BLM. The vesicles used had methylene blue (MB) inside; its release, when the vesicles burst, was monitored by cyclic voltammetry and UV-Vis. The kinetic parameters were determined based on the EIS measurements using Fe(CN)_6^(3-/4-) and Ru(NH_3 )_6^(3+/2+) as redox couples.

Cell adhesion is the first step of cell response to materials and the extracellular matrix (ECM), and is essential to all cell behaviours such as cell proliferation, differentiation, migration and apoptosis for anchor-dependent cells. Therefore, studies of cell attachment have important implications to control and study cell behaviours. During many developed techniques for cell attachment, the manipulation of surface chemistry is a very important method to control initial cell attachment. To control cell adhesion on a two-dimensional surface is a simple model to study cell behaviours, and is a fundamental topic for cell biology, tissue engineering, and the development of biosensors. From the engineering point of view, the preparation of a material with controllable surface chemistry can help studies of cell behaviours and help scientists understand how surface features and chemistry influence cell behaviours. During the fabrication, the challenge is to create a surface with heterogeneous surface properties in the micro scale and subsequently to guide cell initial adhesion. In order to control cell adhesion in a spatial and temporal manner, a photochemical method to control surface chemistry was employed to control the surface property for cell adhesion in this project. Two photocleavable derivatives of the nitrobenzyl group were tried on two types of surfaces: a model self-assembled monolayer (SAM) with alkanethiol-gold surface and biodegradable chitosan. Reactive functional groups on two different surfaces can be inactivated by covalent binding with these photocleavable molecules, and light can be further introduced into the system as a stimulus to recover their reactivity. By simply applying a photomask with diffe