Corneal perforations are medical emergencies in which the cornea is partially or completely ruptured, resulting in the loss of stability of the whole eye. Such situations can be caused by bacterial or fungal keratitis, autoimmune, or ocular-surface related disorders. Corneal perforations, if left untreated, can cause partial or total blindness. Therefore, immediate treatment is necessary. The best treatment available is corneal transplantation; however, due to donor limitation, this treatment is non-feasible. Alternatively, applying cyanoacrylate or fibrin glue is the treatment used clinically. Nonetheless, these treatments have been shown to cause inflammation and result in recurrence of the perforation which may lead to a full thickness donor transplantation in future. Thus, an easily available and applicable, biological and non-immunologic solution is required for a better treatment. For this, injection of in situ crosslinked and biocompatible hydrogels can provide a better long-term solution. Even though there are several different strategies for crosslinking of hydrogels such as chemical crosslinking, enzyme mediated, or UV-initiated crosslinking, there are several limitations in these methods such as cytotoxicity or immunogenic potential of the method. This study involves the development of injectable in situ forming gel crosslinked by Fenton´s reaction, a chemical mimic of horseradish peroxidase (HRP), which can have potential applications for corneal perforations. The polymers used in this study were both synthetic polymers such as poly (ethylene glycol) (PEG) and ECM-derived such as gelatin.The results demonstrated that it is possible to tune the mechanical properties and gelling kinetics of the resulting hydrogel by adjusting the reactant compositions. In vitro cytotoxicity tests were performed for relevant concentrations of Fe (II) and hydrogen peroxide, and have shown that the cells remained viable.

3D bioprinting allows for the manufacturing of tissue-like structures that could be used for culturing and studying cells in a microenvironment representative of the cell’s natural environment. In recent years, hydrogel bioinks from different biomaterials have been in development and utilized in tissue engineering applications. The most common biomaterial is collagen, the main component of the ECM, due to its high biocompatibility. However, collagen bioinks have poor mechanical properties, limiting their use for bioprinting without addition of chemical crosslinks. Efforts have been made in attempts to overcome these issues. In this project collagen hydrogels of high concentration derived from decellularized ECM of rat tail tendons were developed and examined for future use as bioink. After decellularization, the dECM was translated into pre-gels of varying concentrations and exposure to pepsin, to see how this would affect the gelation kinetics and rheological properties. The biochemical profile of the pre-gel consisted of collagen type 1 and various glycosaminoglycans. The pre-gels displayed promising rheological properties for direct printing. Regardless of concentration and pepsin exposure, the pre-gel displayed shear thinning behavior and gelation below 10 min. Increasing the concentration of the hydrogels, increased the storage modulus from 1 kPa to 10 kPA. Increasing the concentration, also affected the gelation temperature to below 37 °C. However, cells could not be cultured within the hydrogels. Further research would need to be done in order to evaluate the cell compatibility of the pre-gels and suitable printing approaches

In the last two years, the COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has impacted the entire world. SARS-CoV-2 detection methods include Polymerase Chain Reaction (PCR), which is expensive, and Rapid Antigen Test, which is not highly sensitive. Therefore, this study aimed for a viral diagnostic tool that is cost-effective and highly sensitive, a biomimetic biosensor.   The aim was to build a biomimetic biosensor using Surface Plasmon Resonance (SPR) based equipment. Three epitopes named here alpha 1, alpha 2, and alpha 3 from the angiotensin converting enzyme-2 (ACE-2), the target receptor for cell entry for SARS-CoV-2 and SARS-CoV in the body, were immobilized on a surface. Then, samples containing WT SARS-CoV-2 RBD, WT SARS-CoV-2 Spike, Delta SARS-CoV-2 RBD, and SARS-CoV RBD were injected over the surface. SPR allowed the detection of any binding that occurred.   The results revealed that the WT SARS-CoV-2 spike protein and the Delta SARS-CoV-2 RBD binding to alpha 2 showed the best results with high signals and high binding affinities. Alpha 1 interestingly showed good binding only two out of six times but the exact reason for that remains unknown. Alpha 3 did not seem to be promising as it either did not bind the analytes at all or was bound with very low signals.   These findings indicate that it is possible to build a biomimetic biosensor using peptides from ACE-2 to detect SARS-CoV-2, but further investigations are needed to optimize it. Future perspectives can include focusing on optimizing alpha 1 efficiency and finding the reason why it is not so stable.     Keywords: SARS-CoV-2, biosensor, SPR, ACE-2, spike, RBD / Adaptable host-cell mimetic receptors for antibody-free sensing of SARS-CoV-2 variants

Cardiovascular diseases are currently the leading cause of death globally. Progression of the disease affects the composition and function of the heart and in many cases subsequently results in heart failure over time where a heart transplant is vital. Therefore, there is a need for medical treatments to stop the progression of the disease. Hydrogels as a biomaterial have been investigated for this purpose, but most known research to date has focused on their bioactive properties. Since a part of the disease progression is affected by the mechanical differences between myocardial tissue and the collagen the body replaces the loss of viable myocardium with after myocardial infarction, this thesis conducted a novel approach of comparing a thiol functionalized collagen hydrogel with a healthy left ventricle in terms of viscoelastic properties for tissue-bulking application. Swelling tests showed that the gel did not swell significantly over time during incubation in phosphate buffer and even if self-healing of the gel after subjection to ultrasound radiation could not be proven and previously used methods to obtain mechanical stiffness of a tissue (compression tests) could not be utilized for soft materials such as hydrogels, the material is of great interest as a candidate for tissue bulking purposes. The gel showed viscoelastic properties similar to the healthy left ventricle and was injectable, to be administrated in a minimally invasive manner, indicating that the material could act as a tissue-bulking agent. This project has developed a new approach to evaluating hydrogels as a biomaterial by comparing it to the viscoelastic characterization of the intended application tissue.

Body dissatisfaction (BD) is a condition derived from negative thoughts and feelings about one's body and is a core symptom of the eating disorder anorexia nervosa (AN). Beingdissatisfied with one’s body is highly present in women and to some extent men. This might be a result of a skewed ideal in combination with social influences. In recent year, research on neurobiological risk factors as well as neuroscientific and cognitive mappings of AN and BD have gained traction, particularly when it comes to studies using neuroimaging- techniques and cognitive tests. Studies have identified brain regions (insular cortex, anterior cingulate cortex, parietal cortex, amygdala, dorsolateral and orbitofrontal areas of the prefrontal cortex) associated with the processing of body shape as well as dysfunctional processing of self-image and body satisfaction. Structural imaging studies of AN patients using CT and MRI have, in many cases, found reduced cerebral volume, increased spinal fluid (CSF) and enlarged ventricles. Usually, food and water restriction has been seen as the cause, and structural deficits in AN patients have shown to improve with weight gain after long-term recovery.

The goal of this literature study was to study the effects of spinal implant wear debris particles on the body in general, and on microglia cells in particular. The method of the literature study was searching for scientific peer-reviewed papers on the topic.  Spinal implants are used to fix spinal problems such as deformities or injuries. All implants wear down in the body. This produces wear debris particles. The body’s immune system reacts to the particles, triggering inflammation, osteolysis and implant loosening. The reaction depends on particle type and the location of the particles. Cobalt chrome particles are more toxic than stainless steel particles. Metal particles are more inflammatory than ceramics and most polymers. Microglia are immune cells specific to the brain and spinal cord. These cells would be one of the cells reacting to wear debris from spinal implants. Not many studies have been made on the interaction between microglia and wear particles. Some cells react differently to wear particles on their own, compared to when they are combined with other cell types. It is important to study the body as a whole system, and not just one cell type, as the results may differ. Several studies have concluded that wear particles induce an inflammatory response, and that the resulting inflammation is mild and does not have any severe negative effects. How much inflammation is required for a severe negative effect such as osteolysis is unclear. In conclusion, the perfect spinal implant does not exist. All spinal implants generate wear debris, and the body reacts to every type of debris. Maybe science will one day find the perfect implant material that does not induce a biological reaction. / Ryggimplantat används för att åtgärda missbildningar, skador och problem i ryggen. Implantat nöts ner i kroppen och då bildas partiklar, som sprids till omkringliggande vävnader. Nötningspartiklar kan orsaka problem, då kroppens immunförsvar reagerar på dem. Detta kan leda till inflammation och infektion, och även att implantatet lossnar. Det kan krävas ytterligare operationer för att ta bort eller byta ut implantat som orsakar problem. Ett bra implantatmaterial slits mindre, vilket skapar färre partiklar som kan orsaka inflammation. Det är också fördelaktigt om partiklarna i sig orsakar mindre inflammation. Mindre inflammation leder till färre biverkningar av implantaten. Makrofager är en typ av immuncell som reagerar på nötningspartiklar. Deras jobb är att skydda kroppen mot hot, till exempel sjukdomar, skadade celler eller främmande föremål såsom nötningspartiklar. Mikrogliaceller är en speciell typ av makrofager som finns i ryggraden och hjärnan. Det är relevant att studera mikrogliaceller, då de kommer reagerar på och påverkas av nötningspartiklar från ryggimplantat. Det finns flera olika typer av implantat, som kan se olika ut, och tillverkas av olika material beroende på användningsområde. Implantat kan vara gjorda av polymerer, keramer, och metaller. Metallerna kan vara till exempel kobolt krom, rostfritt stål eller titan, samt legeringar som kombinerar metaller med ett eller flera andra element.  Implantaten kan vara skruvar, plattor eller stavar som används för att stabilisera delar av ryggraden, eller för att laga en skadad ryggrad. Samma resultat kan fås med hjälp av en så kallad bur (cage på engelska). Det är ett implantat som placeras mellan två kotor och hjälper kotorna att växa ihop. En steloperation tar bort rörligheten mellan två eller flera ryggkotor. Det finns även andra typer av implantat som behåller rörligheten, såsom diskproteser. För att kunna använda implantatet i människokroppen behöver det genomgå olika typer av tester. Först görs in vitro-test, där experiment utförs på celler i till exempel provrör eller petriskålar. In vitro-test studerar cellens reaktion på ett visst material, till exempel om cellerna överlever. Om materialet ger bra resultat i in vitro-testerna, görs in vivo-test, vilket betyder djurförsök. Ett levande djur består av många olika organsystem och celltyper som interagerar med varandra. En celltyp kanske inte påverkas alls av materialet som testas, samtidigt som en annan celltyp påverkas kraftigt. Därför är det viktigt att testa ett materials effekt på en komplicerad organism, såsom ett helt djur, då det kan ge olika resultat jämfört med in vitro-tester (celltester). Om både in vitro och in vivo-testerna är godkända kan materialet testas kliniskt, på människor. Syftet med detta examensarbete var att göra en litteraturstudie av vetenskapliga artiklar om ryggimplantat och deras nötningspartiklars effekt på kroppen i allmänhet, och mikrogliaceller i synnerhet. Litteraturstudiens metod bestod av att söka efter vetenskapliga artiklar relaterade till projektets syfte. Artiklarna skulle handla om ryggimplantat och dess nötningspartiklar. Även den biologiska effekten av implantatet eller partiklarna skulle nämnas i artiklarna.  Studier visar att kroppen påverkas av alla typer av ryggimplantat. Kroppen reagerar olika beroende på var implantaten är placerade, och vilka material de är gjorda av. Några exempel är att kobolt krom har mer negativ effekt än rostfritt stål. Metaller skapar mer inflammation än keramer och de flesta polymerer. Flera studier har kommit fram till att implantatpartiklar skapar en mild inflammation som inte leder till några större skador. Hur mycket inflammation som krävs för att orsaka skador i kroppen, som att implantat lossnar, är oklart. En studie visade att olika kombinationer av celler reagerar olika på implantatpartiklar. Försök på en celltyp gav olika resultat jämfört med försök på en kombination av celltyper. Det visar att det är viktigt att se kroppen som ett komplicerat system, där olika delar av kroppen påverkar varandra. Många studier handlar om hur makrofager reagerar på nötningspartiklar från implantat. Det finns få studier om hur mikrogliaceller påverkas av implantatpartiklar. Vi skulle vilja se framtida studier om mikrogliacellers reaktion på implantatpartiklar av olika material. Sammanfattningsvis har alla material har för- och nackdelar. Inget implantatmaterial är perfekt. Förhoppningsvis leder framtida forskning till ännu bättre implantatmaterial.

Today, the majority of materials used for single-use packaging are petroleum-based synthetic polymers. With increased concern about the environmental protection, efforts have been made to develop alternative biodegradable materials from renewable resources. Starch offers an attractive alternative since it is of low cost and abundant. However, the starch material is brittle without plasticizer and the mechanical properties of starch materials are highly sensitive to moisture. In nature, the plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. This interesting combination of properties is attributed to a network based on cellulose microfibrils. Inspired by this, microfibrillated cellulose (MFC) reinforced starch-based nanocomposites films and foams were prepared. Films with a viscous matrix and MFC contents from 10 to 70wt% were successfully obtained by solvent casting. The films were characterized by DSC, DMA, FE-SEM, XRD, mercury density measurements, and dynamic water vapor sorption (DVS). At 70wt% MFC content a high tensile strength together with high modulus and high work of fracture was observed. This was due to the nanofiber and matrix properties, favourable nanofiber-matrix interaction, a good dispersion of nanofibers and the MFC network. Novel nanocomposite foams were obtained by freeze-drying aquagels prepared from 8wt% solutions of amylopectin starch and MFC. The MFC content was varied from 10 to 70wt%. For composite foam with MFC contents up to 40wt%, improved mechanical properties were observed in compression. The mechanical properties depended both on the cell wall properties and the cell-structure of the foam. The effect of moisture (20-80% RH) on the dynamical properties of composite foam with 40wt% MFC was also investigated and compared to those of neat starch foam. Improved storage modulus was noted with MFC content, which was a result of the nanofiber network in the cell-wall. In addition, the moisture content decreased with MFC content, due to the less hydrophilic nature of MFC. / QC 20101118

Mucous membranes are covered with mucus, a viscoelastic hydrogel that plays an essential role in their protection from shear and pathogens. The viscoelasticity of mucus is owing to mucins, a group of densely glycosylated proteins. Mucins can interact with a wide range of surfaces; thus, there is big interest in exploring and manipulating such interactions for biomedical applications. This thesis presents investigations of mucin interactions with hydrophobic surfaces in order to identify the key features of mucin lubricity, as well as describes the development of materials that are optimized to interact with mucins.   In Paper I we investigated the domains which make mucins outstanding boundary lubricants. The results showed that the hydrophobic terminal domains of mucins play a crucial role in the adsorption and lubrication on hydrophobic surfaces. Specifically, protease digestion of porcine gastric mucins and salivary mucins resulted in the cleavage of these domains and the loss of lubricity and surface adsorption. However, a “rescue” strategy was successfully carried out by grafting hydrophobic phenyl groups to the digested mucins and enhancing their lubricity. This strategy also enhanced the lubricity of polymers which are otherwise bad lubricants.   In Paper II we developed mucoadhesive materials based on genetically engineered partial spider silk proteins. The partial spider silk protein 4RepCT was successfully functionalized with six lysines (pLys-4RepCT), or the Human Galectin-3 Carbohydrate Recognition Domain (hGal3-4RepCT). These strategies were aiming to either non-specific electrostatic interactions between the positive lysines and the negative mucins, or specific binding between the hGal3 and the mucin glycans. Coatings, fibers, meshes and foams were prepared from the new silk proteins, and the adsorption of porcine gastric mucins and bovine submaxillary mucins was measured, demonstrating enhanced adsorption.   The work presented demonstrates how mucin-material interactions can provide us with valuable information for the development of new biomaterials. Specifically, mucin-based and mucin-inspired lubricants could provide desired lubrication to a wide range of surfaces, while our new silk based materials could be valuable tools for the development of mucosal dressings. / Slemhinnor täckts av slem, en viskoelastisk hydrogel som spelar en viktig roll för att skydda mot mekanisk nötning och patogener. Muciner, en grupp av tätt glykosylerade proteiner, spelar en viktig roll i viskoelasticiteten av slem. Eftersom muciner kan interagera med diverse ytor är det av stort intresse att utforska och manipulera sådana interaktioner för biomedicinska tillämpningar. Denna avhandling presenterar undersökningar av mucininteraktioner med hydrofoba ytor för att identifiera de viktigaste egenskaperna hos mucinsmörjning, samt beskriver utveckling av material som optimerades för att interagera med muciner.   I Artikel I undersökte vi de domäner som bidrar till  mucinernas enastående kapacitet som smörjmedel. Resultaten visade att mucinernas hydrofoba terminaldomäner spelar en avgörande roll vid adsorption och smörjning på hydrofoba ytor. Mer specifikt, proteasklyvning av svinmagemuciner och salivmuciner resulterade i klyvningen av dessa domäner och förlust av smörjning och ytadsorption. Genom att länka hydrofobiska fenylgrupper till de uppbrutna mucinerna, lyckades deras smörjningsegenskaper förbättras. Denna strategi förbättrade också smörjningsegenskaper hos andra polymerer som annars har  dåliga smörjningsegenskaper.   I Artikel II utvecklade vi mukoadhesiva material baserade på genetiskt modifierade partiella spindelsilkeproteiner. Spindelsilkeproteinet 4RepCT funktionaliserades framgångsrikt med tillsats av sex lysiner (pLys-4RepCT), eller den mänskliga Galectin-3 karbohydrat igenkänningsdomänen (hGal3-4RepCT). Syftet med dessa strategier var antingen att öka ospecifika elektrostatiska interaktioner mellan de positiva lysinerna och de negativa mucinerna, eller den specifika bindningen mellan hGal3 och mucin-glykanerna. Beläggningar, fibrer, nät och skum framställdes från de nya silkeproteinerna. Efter att adsorption av svinmagsmuciner och bovina submaxillära muciner uppmätts, visade de nya silkeproteinerna förbättrad mucin adsorption.   Detta arbete visar hur interaktioner mellan mucin-material kan bidra med värdefull information för utvecklingen av nya biomaterial. Mucinbaserade och mucininspirerade smörjmedel kan ge önskad smörjning till ett brett spektrum av ytor, medan vår nya silkesbaserad material kan vara ett värdefullt verktyg för utvecklingen av slemhinneförband. / <p>QC 20190412</p>

Wood plastic composite (WPC) materials have seen a continuous market growth worldwide in the last decade. So-called extruded WPC profiles are today mainly used in outdoor applications, e.g. decking, railing and fencing. In outdoor conditions, moisture sorption in the wood component combined with temperature induced movements of the polymer matrix causes deformations of such composites. On the macroscopic scale this may lead to unacceptable warp, cup and bow of the WPC products, but on a microscopic scale, the movements will cause interfacial cracks between the particles and the matrix, resulting in little or no ability to transfer and re-distribute loads throughout the material. Moisture within the composite will also allow fungi and micro organisms to attack the wood particles. The conceptual idea of this work is to use a chemically modified wood component in WPCs to enhance their long term performance. These chemically modified wood particles exhibit reduced susceptibility to moisture, resulting in better dimensional stability and a higher resistance to biological degradation as compared to that of unmodified wood. The objective of this thesis is to study the effects of using modified wood in WPCs on their moisture sorption behaviour, micromorphology and microbiological durability. The modification methods used were acetylation, heat treatment and furfurylation. Equilibrium moisture content (EMC) and sorption behaviour of WPCs were determined by water vapour sorption experiments. The use of thin sections of the composites enabled EMC to be reached within a comparably short time span. The micromorphology was studied by LV-SEM (low vacuum-scanning electron microscope) using a specially designed sample preparation technique based on UV laser. The biological durability was evaluated by laboratory fungal test methods. The moisture sorption experiments showed lower moisture levels for all the composites when modified wood particles were used. This was also reflected in the micromorphological studies where pronounced wood-plastic interfacial cracks were formed due to moisture movement in the composites with unmodified wood particles. The sample preparation technique by UV laser proved to be a powerful tool for preparing surfaces for micromorphological studies without adding mechanical defects caused by the sample preparation technique itself. Results from the durability test showed that WPCs with modified wood particles are highly resistant to decay by fungi. / QC 20101116

Filtration and separation technologies remain as one of the biggest challenges humanity currently faces. The separation of different elements such as bacteria, viruses, heavy metals, particles, and chemical agents require the development of multifunctional membranes. In membrane technology, one of the most promising fabrication techniques is electrospinning, which can produce highly tailored non-woven fibrous multifunctional membranes with a high surface area. On the other hand, cellulose derivatives, like cellulose acetate, have many beneficial properties for filtering technology such as high availability and easy functionalization. Likewise, cellulose nanocrystals are used to improve mechanical properties and functionalize membranes. In this project, a cellulose nanocrystal (CNCs) functionalized cellulose acetate electrospun multifunctional membrane is developed for adsorption and separation of nanosized particles. In this work, cellulose acetate (CA) fibers with an average fiber diameter of approximately 900 nm were electrospun and tested as membranes for size and affinity based filtration. First, the electrospinning process was optimized regarding solution and process parameters. As a result, solution parameters were found to be 12 wt% solid content CA dissolved in a 1:1 acetone:acetic acid solution. Regarding process parameters, the suitable electrospinning parameters were found to be 18 kV applied voltage, a feeding rate of 5 mL/h, and a tip-to-collector distance of 20 cm.   The electrospun CA membrane was coated with cationic (+) and anionic (-) cellulose nanocrystals up to a 25 wt% concentration. The incorporation of CNCs, of either anionic or cationic surface charge, affected membrane wettability. The neat CA membrane had a hydrophobic behavior with a contact angle of 110°. The addition of CNCs decrease contact angle, to 31.5° for CA-CNCs(-) and 50° for CA-CNCs(+), which resulted in functionalized membranes with a hydrophilic behavior. Both functionalized membranes managed to maintain high flux values. CA-CNCs(-) maintained a flux of 9500 Lm−2h−1, while CA-CNCs(+) maintained a flux of 6700 Lm−2h−1. The addition of cellulose nanocrystals improved the mechanical properties of the CA membranes. The tensile strength increases from 410 kPa to 4990 kPa for CA-CNCs(-) membranes and 3010 MPa for CA-CNCs(+) membranes, and is accompanied by an increase in Young’s modulus as well. To evaluate the adsorption efficiency and size-exclusion filtration, an anionic dye (Congo red), a cationic dye (Victoria blue), and 500 nm model particles were used. CA-CNC(-) membranes achieved a removal efficiency of 96% of 500 nm particles with an affinity-based dye removal of 63% of Victoria blue dye. On the other hand, CA-CNC(+) membranes achieved a removal efficiency of 43% of 500 nm particles with a dye removal of 27% of Congo red dye. In this regard, CA-CNC(-) membranes were the best candidate for size-exclusion filtration, while also maintaining a good level of adsorption. Cellulose based composite membranes were successfully produced as multifunctional filters that could act in both size-exclusion regime and affinity-based regime. A cellulose acetate fibrous membrane was produced by electrospinning, tuning for fiber size and porosity, while the incorporation of cellulose nanocrystals functionalizes the membranes and enhance mechanical properties, and wettability.