| 1. |
- Blakeley, Matthew, et al.
(författare)
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Lectin-Functionalized Polyethylene Glycol for Relief of Mucosal Dryness
- 2022
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Ingår i: Advanced Healthcare Materials. - : Wiley. - 2192-2640 .- 2192-2659. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- The importance of lubrication between oral surfaces provided by the salivary film is most acutely apparent when it is disrupted, a prevalent consequence of salivary gland hypofunction experienced with aging, a symptom of certain diseases, or a side effect of some medical interventions. Sufferers report difficulty with speech and oral food processing and collectively is detrimental to quality of life. Polyethylene glycol (PEG) is widely employed as a successful biocompatible boundary lubricant in engineering and biomedical applications. It is hypothesized that the immobilization of PEG to biological materials such as oral epithelial cells and tissue can mimic the salivary film and provide durable relief from the symptoms of mucosal dryness. To do so, PEG is functionalized with a sugar binding lectin (wheat germ agglutinin) to enhance epithelial adhesion through lectin-sugar interactions. Retention and lubricity are characterized on an ex vivo oral tissue tribology rig. WGA-PEG coats and retains on mucin films, oral epithelial cells, and porcine tongue tissue, and offers sustained reduction in coefficient of friction (COF). WGA-PEG could be developed into a useful topical treatment for reducing oral friction and the perception of dry mouth.
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| 2. |
- Brilhante, Raimunda Sâmia Nogueira, et al.
(författare)
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Antifungal Activity of Chitosan against Histoplasma capsulatum in Planktonic and Biofilm Forms : A Therapeutic Strategy in the Future?
- 2023
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Ingår i: Journal of Fungi. - : MDPI AG. - 2309-608X. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- Histoplasmosis is a respiratory disease caused by Histoplasma capsulatum, a dimorphic fungus, with high mortality and morbidity rates, especially in immunocompromised patients. Considering the small existing therapeutic arsenal, new treatment approaches are still required. Chitosan, a linear polysaccharide obtained from partial chitin deacetylation, has anti-inflammatory, antimicrobial, biocompatibility, biodegradability, and non-toxicity properties. Chitosan with different deacetylation degrees and molecular weights has been explored as a potential agent against fungal pathogens. In this study, the chitosan antifungal activity against H. capsulatum was evaluated using the broth microdilution assay, obtaining minimum inhibitory concentrations (MIC) ranging from 32 to 128 µg/mL in the filamentous phase and 8 to 64 µg/mL in the yeast phase. Chitosan combined with classical antifungal drugs showed a synergic effect, reducing chitosan’s MICs by 32 times, demonstrating that there were no antagonistic interactions relating to any of the strains tested. A synergism between chitosan and amphotericin B or itraconazole was detected in the yeast-like form for all strains tested. For H. capsulatum biofilms, chitosan reduced biomass and metabolic activity by about 40% at 512 µg/mL. In conclusion, studying chitosan as a therapeutic strategy against Histoplasma capsulatum is promising, mainly considering its numerous possible applications, including its combination with other compounds.
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| 3. |
- Choi, Hyungryul J., et al.
(författare)
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Superoleophilic Titania Nanoparticle Coatings with Fast Fingerprint Decomposition and High Transparency
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:9, s. 8354-8360
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Tidskriftsartikel (refereegranskat)abstract
- Low surface tension sebaceous liquids such as human fingerprint oils are readily deposited on high energy surfaces such as clean glass, leaving smudges that significantly lower transparency. There have been several attempts to prevent formation of these dactylograms on glass by employing oil-repellent textured surfaces. However, nanotextured superoleophobic coatings typically scatter visible light, and the intrinsic thermodynamic metastability of the composite superoleophobic state can result in failure of the oil repellency under moderate contact pressure. We develop titania-based porous nanoparticle coatings that are superoleophilic and highly transparent and which exhibit short time scales for decomposition of fingerprint oils under ultraviolet light. The mechanism by which a typical dactylogram is consumed combines wicking of the sebum into the nanoporous titania structure followed by photocatalytic degradation. We envision a wide range of applications because these TiO2 nanostructured surfaces remain photocatalytically active against fingerprint oils in natural sunlight and are also compatible with flexible glass substrates.
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| 4. |
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| 5. |
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| 6. |
- Jiang, Kun, et al.
(författare)
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Engineering Surfaces with Immune Modulating Properties of Mucin Hydrogels
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:35, s. 39727-39735
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogels of cross-linked mucin glycoproteins (Muc-gel) have shown strong immune-modulating properties toward macrophages in vitro, which are translated in vivo by the dampening of the foreign body response to implantation in mice. Beyond mucin hydrogels, other biomaterials such as sensors, electrodes, and other long-term implants would also benefit from such immune-modulating properties. In this work, we aimed to transfer the bioactivity observed for three-dimensional Muc-gels to the surface of two model materials by immobilizing mucin into thin films (Muc-film) using covalent layer-by-layer assembly. We tested how the surface immobilization of mucins affects macrophage responses compared to Muc-gels. We showed that Muc-films on soft polyacrylamide gels mimic Muc-gel in their modulation of macrophage responses with activated gene expression of inflammatory cytokines on day 1 and then dampening them on day 3. Also, the markers of polarized macrophages, M1 and M2, were expressed at the same level for macrophages on Muc-film-coated soft polyacrylamide gels and Muc-gel. In contrast, Muc-film-coated hard polystyrene led to a different macrophage response compared to Muc-gel, having no activated expression of inflammatory cytokines and a different M1 marker expression. This suggested that the substrate mechanical properties and mucin molecular configuration determined by substrate-mucin interactions affect mucin immune-modulating properties. We conclude that mucin immune-modulating properties can be transferred to materials by mucin surface immobilization but will be dependent on the substrate chemical and mechanical properties.
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| 7. |
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| 8. |
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| 9. |
- Jiang, Kun, et al.
(författare)
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Modulating the Bioactivity of Mucin Hydrogels with Crosslinking Architecture
- 2021
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31:10
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogels made of crosslinked macromolecules used in regenerative medicine technologies can be designed to affect the fate of surrounding cells and tissues in defined ways. Their function typically depends on the type and number of bioactive moieties such as receptor ligands present in the hydrogel. However, the detail in how such moieties are presented to cells can also be instrumental. In this work, how the crosslinking architecture of a hydrogel can affect its bioactivity is explored. It is shown that bovine submaxillary mucins, a highly glycosylated and immune-modulating protein, exhibit strikingly different bioactivities whether they are crosslinked through their glycans or their protein domains. Both the susceptibility to enzymatic degradation and macrophage response are affected, while rheological properties and barrier to diffusion are mostly unaffected. The results suggest that crosslinking architecture affects the accessibility of the substrate to proteases and the pattern of sialic acid residues exposed to the macrophages. Thus, modulating the accessibility of binding sites through the choice of the crosslinking strategy appears as a useful parameter to tune the bioactivity of hydrogel-based systems.
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| 10. |
- Jiang, Kun
(författare)
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Modulating the structure-function relationship of mucin materials
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mucus covers the epithelium surfaces playing a key role in the barrier, hydration, lubrication and bioactivity functions for the human body, and mucins are the fundamental components of mucus which provide such functions. However, many details in how these functions are related to the many structural features of mucins are still unknown. In this thesis, strategies were developed to modify mucin structures in defined ways to gain insights and controls over several key functions of this molecule. We altered functional motifs on the mucin molecules, and changed the conformation of mucin networks to modulate the accessibility of such functional motifs. Then functional outcomes, including macrophage responses, diffusion of molecules through mucin networks, and mucin lubricity were studied. This thesis is organized into three parts according to the three functions. We found that the responses of macrophage to mucins were modulated by changing the location of crosslinks between mucins and by the immobilization of mucins onto surfaces. Mucins’ bottle-brush structure allowed their crosslinking either via the protein backbone or via the glycan side chains with similar crosslinking density. With the same crosslinking structure, the placement of mucin thin film on hard substrate and soft substrate led to different macrophage responses, and only mucin coating on soft gel induced similar immune responses as that of mucin gels. A better understanding of how mucin bioactivity, and specifically immune-modulating properties, can be modulated, provide new strategies to develop biomaterials with defined bioactivities. This work could also inspire innovative treatments to modulate mucin bioactivities in vivo to treat mucin-related diseases such as for mucinous cancers. The diffusion of molecules through mucin gels was modulated by changing the gel network and their affinity filtration capacity. By locating the crosslinking sites on the protein backbone or the glycan chains, the gel network remained the same with similar diffusion profiles of dextrans. However, with simple change of mucin concentration, molecules of different size diffused faster in gels with lower mucin concentration. The affinity filtration of mucin gel was modulated by removing sialic acids, which acts as binding sites for molecules or cells via electrostatic interactions or specific binding, and the binding can slow down diffusion of cells or molecules. By altering sialic acid contents, the diffusion of charged dextran was modulated and the penetration of sperms was increased. With the understanding, mucin gels with controlled permeability can be designed for loading drugs or encapsulating tissue. And strategies can be developed in the future for treating mucus barrier related disease in vivo, such as inflammatory bowel disease.The hydration & lubrication of mucin coating was modulated with changed mucin structure and removal of associated impurities. The hydration of mucin coatings remained the same, but their lubricity was lost by removing negatively charged sugars. However, the components associated with mucin, such as DNA, compensated for the missing of negative sugars. Commercial PGM was found with damaged glycosylation and missing peptide domains, and its lubricity was lost completely compared to lab-purified mucins. With this knowledge, mucin structure can be modulated for desired hydration and lubrication performance, and this can inspire to develop strategies for restoring their hydration and lubricity in vivo during diseases, such as dry eye.
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| 11. |
- Kaesdorf, Benjamin T., et al.
(författare)
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Mucin-Inspired Lubrication on Hydrophobic Surfaces
- 2017
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Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 18:8, s. 2454-2462
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Tidskriftsartikel (refereegranskat)abstract
- In the human body, high-molecular-weight glycoproteins called mucins play a key role in protecting epithelial surfaces against pathogenic attack, controlling the passage of molecules toward the tissue and enabling boundary lubrication with very low friction coefficients. However, neither the molecular mechanisms nor the chemical motifs of those biomacromolecules involved in these fundamental processes are fully understood. Thus, identifying the key features that render biomacromolecules such as mucins outstanding boundary lubricants could set the stage for creating versatile artificial superlubricants. We here demonstrate the importance of the hydrophobic terminal peptide domains of porcine gastric mucin (MUCSAC) and human salivary mucin (MUCSB) in the processes of adsorbing to and lubricating a hydrophobic PDMS surface. Tryptic digestion of those mucins results in removal of those terminal domains, which is accompanied by a loss of lubricity as well as surface adsorption. We show that this loss can in part be compensated by attaching hydrophobic phenyl groups to the glycosylated central part of the mucin macromolecule. Furthermore, we demonstrate that the simple biopolysaccharide dextran can be functionalized with hydrophobic groups which confers efficient surface adsorption and good lubricity on PDMS to the polysaccharide.
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| 12. |
- Kimna, Ceren, et al.
(författare)
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DNA Strands Trigger the Intracellular Release of Drugs from Mucin-Based Nanocarriers
- 2021
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 15:2, s. 2350-2362
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Tidskriftsartikel (refereegranskat)abstract
- Gaining control over the delivery of therapeutics to a specific disease site is still very challenging. However, especially when cytotoxic drugs such as chemotherapeutics are used, the importance of a control mechanism that can differentiate "sick" target cells from the surrounding healthy tissue is pivotal. Here, we designed a nanoparticle-based drug delivery process, which releases an active agent only in the presence of a specific trigger DNA sequence. With this strategy, we are able to initiate the release of therapeutics into the cytosol with high efficiency. Furthermore, we demonstrate how an endogenous marker (e.g., a specific miRNA sequence) that is overexpressed in the initial phases of certain cancer types can be used as a stimulus to autonomously initiate intracellular drug release-and only in cells where this pathophysiological marker is present. We expect that this precisely controlled delivery mechanism can facilitate the design of site-specific treatments for such diseases, where an overexpression of signature oligonucleotide sequences has been identified.
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| 13. |
- Kootala, Sujit, et al.
(författare)
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Reinforcing Mucus Barrier Properties with Low Molar Mass Chitosans
- 2018
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 19:3, s. 872-882
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Tidskriftsartikel (refereegranskat)abstract
- The mucus gel covers the wet epithelia that forms the inner lining of the body. It constitutes our first line of defense protecting the body from infections and other deleterious molecules. Failure of the mucus barrier can lead to the inflammation of the mucosa such as in inflammatory bowel diseases. Unfortunately, there are no effective strategies that reinforce the mucus barrier properties to recover or enhance its ability to protect the epithelium. Herein, we describe a mucus engineering approach that addresses this issue where we physically cross-link the mucus gel with low molar mass chitosan variants to reinforce its barrier functions. We tested the effect of these chitosans on mucus using in-lab purified porcine gastric mucins, which mimic the native properties of mucus, and on mucus-secreting HT29-MTX epithelial cell cultures. We found that the lowest molar mass chitosan variant (degree of polymerization of 8) diffuses deep into the mucus gels while physically cross-linking the mucin polymers, whereas the higher molar mass chitosan variants (degree of polymerization of 52 and 100) interact only superficially. The complexation resulted in a tighter mucin polymer mesh that slowed the diffusion of dextran polymers and of the cholera toxin B subunit protein through the mucus gels. These results uncover a new use for low molar mass mucoadhesive polymers such as chitosans as noncytotoxic mucosal barrier enhancers that could be valuable in the prevention and treatment of mucosal diseases.
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| 14. |
- Kretschmer, Manuel, et al.
(författare)
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Synthetic Mucin Gels with Self-Healing Properties Augment Lubricity and Inhibit HIV-1 and HSV-2 Transmission
- 2022
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Ingår i: Advanced Science. - : John Wiley and Sons Inc. - 2198-3844. ; 9:32
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Tidskriftsartikel (refereegranskat)abstract
- Mucus is a self-healing gel that lubricates the moist epithelium and provides protection against viruses by binding to viruses smaller than the gel's mesh size and removing them from the mucosal surface by active mucus turnover. As the primary nonaqueous components of mucus (≈0.2%–5%, wt/v), mucins are critical to this function because the dense arrangement of mucin glycans allows multivalence of binding. Following nature's example, bovine submaxillary mucins (BSMs) are assembled into “mucus-like” gels (5%, wt/v) by dynamic covalent crosslinking reactions. The gels exhibit transient liquefaction under high shear strain and immediate self-healing behavior. This study shows that these material properties are essential to provide lubricity. The gels efficiently reduce human immunodeficiency virus type 1 (HIV-1) and genital herpes virus type 2 (HSV-2) infectivity for various types of cells. In contrast, simple mucin solutions, which lack the structural makeup, inhibit HIV-1 significantly less and do not inhibit HSV-2. Mechanistically, the prophylaxis of HIV-1 infection by BSM gels is found to be that the gels trap HIV-1 by binding to the envelope glycoprotein gp120 and suppress cytokine production during viral exposure. Therefore, the authors believe the gels are promising for further development as personal lubricants that can limit viral transmission. © 2022 The Authors.
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| 15. |
- Marczynski, M., et al.
(författare)
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Charged glycan residues critically contribute to the adsorption and lubricity of mucins
- 2019
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Ingår i: Colloids and Surfaces B. - : Elsevier B.V.. - 0927-7765 .- 1873-4367.
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Tidskriftsartikel (refereegranskat)abstract
- In the human body, mucin glycoproteins efficiently reduce friction between tissues and thereby protect the mucosa from mechanical damage. Mucin lubricity is closely related to their molecular structure: it has been demonstrated previously that the hydrophobic termini of mucins critically contribute to their lubricity. If and how intrinsic sources of negative charge in mucins, e.g., sulfated glycans and sialic acid residues, are relevant for the tribological behavior of mucin solutions has, however, not been addressed yet. In this manuscript, we show that the removal of either sialic acid or sulfate groups, which comprise only a minor amount of the total molecular weight, from MUC5B drastically reduces its lubricity. For MUC5AC solutions, however, this effect only occurs once mucin-associated DNA is removed as well. We find that neither the hydration state nor the average conformation of mucins adsorbed onto hydrophilic or hydrophobic surfaces is affected by the removal of anionic sugars. Instead, our data suggests that a loss of anionic sugars mainly influences the dynamic adsorption process of mucins onto both hydrophilic and hydrophobic surfaces.
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| 16. |
- Marczynski, Matthias, et al.
(författare)
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Structural Alterations of Mucins Are Associated with Losses in Functionality
- 2021
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Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 22:4, s. 1600-1613
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Tidskriftsartikel (refereegranskat)abstract
- Commercial mucin glycoproteins are routinely used as a model to investigate the broad range of important functions mucins fulfill in our bodies, including lubrication, protection against hostile germs, and the accommodation of a healthy microbiome. Moreover, purified mucins are increasingly selected as building blocks for multifunctional materials, i.e., as components of hydrogels or coatings. By performing a detailed side-by-side comparison of commercially available and lab-purified variants of porcine gastric mucins, we decipher key molecular motifs that are crucial for mucin functionality. As two main structural features, we identify the hydrophobic termini and the hydrophilic glycosylation pattern of the mucin glycoprotein; moreover, we describe how alterations in those structural motifs affect the different properties of mucins-on both microscopic and macroscopic levels. This study provides a detailed understanding of how distinct functionalities of gastric mucins are established, and it highlights the need for high-quality mucins-for both basic research and the development of mucin-based medical products.
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| 17. |
- Miranda-Martinez, Andres, et al.
(författare)
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Portable Quartz Crystal Resonator Sensor for Characterising the Gelation Kinetics and Viscoelastic Properties of Hydrogels
- 2022
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Ingår i: Gels. - : MDPI AG. - 2310-2861. ; 8:11, s. 718-
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogel biomaterials have found use in various biomedical applications partly due to their biocompatibility and tuneable viscoelastic properties. The ideal rheological properties of hydrogels depend highly on the application and should be considered early in the design process. Rheometry is the most common method to study the viscoelastic properties of hydrogels. However, rheometers occupy much space and are costly instruments. On the other hand, quartz crystal resonators (QCRs) are devices that can be used as low-cost, small, and accurate sensors to measure the viscoelastic properties of fluids. For this reason, we explore the capabilities of a low-cost and compact QCR sensor to sense and characterise the gelation process of hydrogels while using a low sample amount and by sensing two different crosslink reactions: covalent bonds and divalent ions. The gelation of covalently crosslinked mucin hydrogels and physically crosslinked alginate hydrogels could be monitored using the sensor, clearly distinguishing the effect of several parameters affecting the viscoelastic properties of hydrogels, including crosslinking chemistry, polymer concentrations, and crosslinker concentrations. QCR sensors offer an economical and portable alternative method to characterise changes in a hydrogel material's viscous properties to contribute to this type of material design, thus providing a novel approach.
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| 18. |
- Ornithopoulou, Eirini
(författare)
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Hierarchical Assembly Investigations and Multiscale Characterization of Protein-based Materials : Insights from Whey Protein Nanofibrils and Recombinant Spider Silk Microspheres
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Protein-based materials, with their unique properties of combining high strength, while maintaining elasticity, and their inherent biocompatibility, hold immense potential for various applications. In order to harness these properties, we need to understand and control how protein building blocks come together to form hierarchically structured materials. Using critical thinking when combining different proteins may lead to advanced materials with synergistic effects that can tackle complex problems such as targeted drug delivery. This thesis presents an investigation into the behavior of some protein-based materials, specifically whey protein isolate nanofibrils, β-lactoglobulin peptide fragment assemblies, and recombinant spider silk microspheres.In Paper I, the hierarchical assembly and packing behavior of whey protein nanofibrils were in situ investigated using a Liquid Bridge Induced Assembly setup and X-ray Scattering, along with Atomic Force Microscopy and Scanning Electron Microscopy. The results demonstrated that the alignment of straight and curved fibrils was affected by temperature and fibril size, providing insights into assembly dynamics for future material production.In Paper II, the impact of nanoscale features of whey protein nanofibrils on the morphology of films was investigated. It was found that controlling fibril size and employing fast-drying protocols could manipulate macroscale features without sacrificing the functional properties of the nanofibrils.In Paper III, the nanoscale morphology, molecular arrangement, and polymorphism of protein nanofibrils formed by a synthetic peptide fragment derived from β-lactoglobulin were examined. Β-lactoglobulin is the only nanofibril forming component in whey protein isolate. Results suggested that polymorphism stems from protofilament packing differences at the nanoscale, and a possible parallel steric zipper packing.In Paper IV, the self-assembly behavior of a recombinant spider silk protein in physiological like buffer and with the addition of hyaluronic acid was explored. The self-assembled FN-silk microspheres demonstrated a fibrillar or porous mesostructure. 2D and 3D cell culture trials show that the microspheres could have potential applications in biomedicine.Taken together, the acquired knowledge will contribute to our fundamental understanding of protein-based materials, especially those similar to PNF-based and recombinant spider silk-based materials and inform the design of improved and innovative materials in biomanufacturing, such as functional textiles and surface biofunctionalization.
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| 19. |
- Ornithopoulou, Eirini, et al.
(författare)
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Self-assembly of RGD-functionalized recombinant spider silk protein into microspheres in physiological buffer and in the presence of hyaluronic acid
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Biomaterials made of self-assembling protein building blocks are widely explored for biomedical applications, for example as drug carriers, tissue engineering scaffolds, and functionalized coatings. It has previously been shown that a recombinant spider silk protein functionalized with a cell binding motif from fibronectin, FN-4RepCT (FN-silk), self-assembles into fibrillar structures at interfaces, i.e. membranes, fibers, or foams at liquid/air interfaces, and fibrillar coatings at liquid/solid interfaces. Recently, we observed that FN-silk also assembles into microspheres in the bulk of a physiological buffer (PBS) solution. Herein, we investigate the self-assembly process of FN-silk into microspheres in the bulk, and how its progression is affected by the presence of hyaluronic acid (HA), both in solution and in a cross-linked HA hydrogel. Moreover, we characterize the size, morphology, mesostructure and protein secondary structure of the FN-silk microspheres prepared in PBS and HA. Finally, we examine how the FN-silk microspheres can be used to mediate cell adhesion and spreading of human mesenchymal stem cells (hMSCs) during cell culture. These investigations contribute to our fundamental understanding of the self-assembly of silk protein into materials and demonstrate the use of silk microspheres as additives for cell culture applications.
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| 20. |
- Ornithopoulou, Eirini, et al.
(författare)
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Self-Assembly of RGD-Functionalized Recombinant Spider Silk Protein into Microspheres in Physiological Buffer and in the Presence of Hyaluronic Acid
- 2023
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Ingår i: ACS Applied Bio Materials. - : American Chemical Society (ACS). - 2576-6422. ; 6:9, s. 3696-3705
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Tidskriftsartikel (refereegranskat)abstract
- Biomaterials made of self-assembling protein building blocks are widely explored for biomedical applications, for example, as drug carriers, tissue engineering scaffolds, and functionalized coatings. It has previously been shown that a recombinant spider silk protein functionalized with a cell binding motif from fibronectin, FN-4RepCT (FN-silk), self-assembles into fibrillar structures at interfaces, i.e., membranes, fibers, or foams at liquid/air interfaces, and fibrillar coatings at liquid/solid interfaces. Recently, we observed that FN-silk also assembles into microspheres in the bulk of a physiological buffer (PBS) solution. Herein, we investigate the self-assembly process of FN-silk into microspheres in the bulk and how its progression is affected by the presence of hyaluronic acid (HA), both in solution and in a cross-linked HA hydrogel. Moreover, we characterize the size, morphology, mesostructure, and protein secondary structure of the FN-silk microspheres prepared in PBS and HA. Finally, we examine how the FN-silk microspheres can be used to mediate cell adhesion and spreading of human mesenchymal stem cells (hMSCs) during cell culture. These investigations contribute to our fundamental understanding of the self-assembly of silk protein into materials and demonstrate the use of silk microspheres as additives for cell culture applications.
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| 21. |
- Petrou, Georgia, et al.
(författare)
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Engineering mucoadhesive silk
- 2018
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Ingår i: Abstracts of Papers of the American Chemical Society. - : American Chemical Society (ACS). - 0065-7727. ; 255
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 22. |
- Petrou, Georgia, et al.
(författare)
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Genetically Engineered Mucoadhesive Spider Silk
- 2018
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Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 19:8, s. 3268-3279
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Tidskriftsartikel (refereegranskat)abstract
- Mucoadhesion is defined as the adhesion of a material to the mucus gel covering the mucous membranes. The mechanisms controlling mucoadhesion include nonspecific electrostatic interactions and specific interactions between the materials and the mucins, the heavily glycosylated proteins that form the mucus gel. Mucoadhesive materials can be used to develop mucosal wound dressings and noninvasive transmucosal drug delivery systems. Spider silk, which is strong, biocompatible, biodegradable, nontoxic, and lightweight would serve as an excellent base for the development of such materials. Here, we investigated two variants of the partial spider silk protein 4RepCT genetically engineered in order to functionalize them with mucoadhesive properties. The pLys-4RepCT variant was functionalized with six cationically charged lysines, aiming to provide nonspecific adhesion from electrostatic interactions with the anionically charged mucins, while the hGal3-4RepCT variant was genetically fused with the Human Galectin-3 Carbohydrate Recognition Domain which specifically binds the mucin glycans Gal beta 1-3GlcNAc and Gal beta 1-4GlcNAc. First, we demonstrated that coatings, fibers, meshes, and foams can be readily made from both silk variants. Measured by the adsorption of both bovine submaxillary mucin and pig gastric mucin, the newly produced silk materials showed enhanced mucin binding properties compared with materials of wild-type (4RepCT) silk. Moreover, we showed that pLys-4RepCT silk coatings bind mucins through electrostatic interactions, while hGal3-4RepCT silk coatings bind mucins through specific glycan-protein interactions. We envision that the two new mucoadhesive silk variants pLys-4RepCT and hGal3-4RepCT, alone or combined with other biofunctional silk proteins, constitute useful new building blocks for a range of silk protein-based materials for mucosal treatments.
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| 23. |
- Petrou, Georgia, 1991-
(författare)
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Investigating mucin interactions with diverse surfaces for biomedical applications
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 24. |
- Petrou, Georgia, et al.
(författare)
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Mucins as multifunctional building blocks of biomaterials
- 2018
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Ingår i: Biomaterials Science. - : Royal Society of Chemistry. - 2047-4830 .- 2047-4849. ; 6:9, s. 2282-2297
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Forskningsöversikt (refereegranskat)abstract
- Mucins are large glycoproteins that are ubiquitous in the animal kingdom. Mucins coat the surfaces of many cell types and can be secreted to form mucus gels that assume important physiological roles in many animals. Our growing understanding of the structure and function of mucin molecules and their functionalities has sparked interest in investigating the use of mucins as building blocks for innovative functional biomaterials. These pioneering studies have explored how new biomaterials can benefit from the barrier properties, hydration and lubrication properties, unique chemical diversity, and bioactivities of mucins. Owing to their multifunctionality, mucins have been used in a wide variety of applications, including as antifouling coatings, as selective filters, and artificial tears and saliva, as basis for cosmetics, as drug delivery materials, and as natural detergents. In this review, we summarize the current knowledge regarding key mucin properties and survey how they have been put to use. We offer a vision for how mucins could be used in the near future and what challenges await the field before biomaterials made of mucins and mucin-mimics can be translated into commercial products.
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| 25. |
- Schimpf, Ulrike, et al.
(författare)
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Assessment of Oligo-Chitosan Biocompatibility toward Human Spermatozoa
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:50, s. 46572-46584
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Tidskriftsartikel (refereegranskat)abstract
- The many interesting properties of chitosan polysaccharides have prompted their extensive use as biomaterial building blocks, for instance as antimicrobial coatings, tissue engineering scaffolds, and drug delivery vehicles. The translation of these chitosan-based systems to the clinic still requires a deeper understanding of their safety profiles. For instance, the widespread claim that chitosans are spermicidal is supported by little to no data. Herein, we thoroughly investigate whether chitosan oligomer (CO) molecules can impact the functional and structural features of human spermatozoa. By using a large number of primary sperm cell samples and by isolating the effect of chitosan from the effect of sperm dissolution buffer, we provide the first realistic and complete picture of the effect of chitosans on sperms. We found that CO binds to cell surfaces or/and is internalized by cells and affected the average path velocity of the spermatozoa, in a dose-dependent manner. However, CO did not affect the progressive motility, motility, or sperm morphology, nor did it cause loss of plasma membrane integrity, reactive oxygen species production, or DNA damage. A decrease in spermatozoa adenosine triphosphate levels, which was especially significant at higher CO concentrations, points to possible interference of CO with mitochondrial functions or the glycolysis processes. With this first complete and in-depth look at the spermicidal activities of chitosans, we complement the complex picture of the safety profile of chitosans and inform on further use of chitosans in biomedical applications.
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| 26. |
- Schimpf, Ulrike, 1977-, et al.
(författare)
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Topical reinforcement of the cervical mucus barrier to sperm
- 2022
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Ingår i: Science Translational Medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6234 .- 1946-6242. ; 14:673
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Tidskriftsartikel (refereegranskat)abstract
- Close to half of the world’s pregnancies are still unplanned, reflecting a clear unmet need in contraception. Ideally, a contraceptive would provide the high efficacy of hormonal treatments, without systemic side effects. Here, we studied topical reinforcement of the cervical mucus by chitosan mucoadhesive polymers as a form of female contraceptive. Chitosans larger than 7 kDa effectively cross-linked human ovulatory cervical mucus to prevent sperm penetration in vitro. We then demonstrated in vivo using the ewe as a model that vaginal gels containing chitosan could stop ram sperm at the entrance of the cervical canal and prevent them from reaching the uterus, whereas the same gels without chitosan did not substantially limit sperm migration. Chitosan did not affect sperm motility in vitro or in vivo, suggesting reinforcement of the mucus physical barrier as the primary mechanism of action. The chitosan formulations did not damage or irritate the ewe vaginal epithelium, in contrast to nonoxynol-9 spermicide. The demonstration that cervical mucus can be reinforced topically to create an effective barrier to sperm may therefore form the technological basis for muco-cervical barrier contraceptives with the potential to become an alternative to hormonal contraceptives.
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| 27. |
- Weston, Abby, et al.
(författare)
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The influence of ions on the lubricative abilities of mucin and the role of sialic acids
- 2023
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- Mucus reduces friction between epithelial surfaces by providing lubrication in the boundary and mixed regime. Mucins, the main macromolecule, are heavily glycosylated proteins that polymerise and retain water molecules, resulting in a hydrated biogel. It is assumed that positively charged ions can influence mucin film structure by screening the electrostatic repulsions between the negatively charged glycans on mucin moieties and draw in water molecules via hydration shells. The ionic concentration can vary significantly in different mucus systems and here we show that increasing the ionic concentration in mucin films leads to an increase in lubrication between two polydimethylsiloxane surfaces at sliding contact in a compliant oral mimic. Mucins were found to bind sodium ions in a concentration-dependent manner and increased ionic concentration appears to cause mucin films to swell when assessed by Quartz Crystal hiMicrobalance with Dissipation (QCM-D) analysis. Furthermore, we determined that the removal of negatively charged sialic acid moieties by sialidase digestion resulted in reduced adsorption to hydrophilic surfaces but did not affect the swelling of mucin films with increasing ionic concentrations. Moreover, the coefficient of friction was increased with sialic acid removal, but lubrication was still increased with increasing ionic concentrations. Taken together this suggests that sialic acids are important for lubrication and may exert this through the sacrificial layer mechanism. Ionic concentration appears to influence mucin films and their lubrication, and sialic acids, at least partly, may be important for ion binding.
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| 28. |
- Wittig, Cornelius, 1994-
(författare)
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Experiments on biofilm formation and growth in laminar flows
- 2024
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interaction between fluid dynamics and biofilm growth plays a key role in both medical and industrial applications. Biofilms, or bacteria that are embedded in a protective matrix of extracellular polymeric substances, settle on interfaces such as on implanted devices or ship hulls. These biofilms canthen cause infectious diseases or significantly increase drag. In this thesis, we investigate the influence of flow, specifically shear stress, on the development of biofilm.The first paper presents a new facility to investigate biofilm growth in laminar flow cells over extended periods of up to several weeks. Optical coherence tomography is used to obtain three-dimensional scans of the biofilm structure at regular intervals. From these time series, we derive a simple model that relates the growth of an individual microcolony to the growth of the full biofilm depending on the wall shear stress. Additionally, we show that biofilm streamers, thin, flexible filaments that extend into the bulk flow, can form on sharp biofilm structures in laminar flow, even if the substratum is a flat surface.The second contribution is a report detailing preliminary studies on biofilm experiments. We investigate the formation of biofilm in the shear layer behinda backward-facing step. The results indicate a maximum shear stress, beyond which biofilm growth is inhibited. We also provide guidelines for the design of experimental setups for the investigation of the influence of fluid dynamics on biofilm and vice-versa.
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| 29. |
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| 30. |
- Wittig, Cornelius, 1994-, et al.
(författare)
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The role of fluid friction in streamer formation and biofilm growth
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Bacillus subtilis biofilms were grown in laminar channel flow at wall shear stress spanning one order of magnitude (tau_w = 0.068 Pa to tau_w = 0.67 Pa). We monitor, non-invasively, the evolution of the three-dimensional distribution of biofilm over seven days using optical coherence tomography (OCT). The obtained biofilms consist of many microcolonies where the characteristic colony has a base structure in the form of a leaning pillar and a streamer in the form of a thin filament that originates near the tip of the pillar. While the shape, size and distribution of these microcolonies depend on the imposed shear stress, the same structural features appear consistently for all shear stress values. The formation of streamers seems to occur after the development of a base structure, suggesting that the latter induces a curved secondary flow that triggers the formation of the streamers. Moreover, we observe that the biofilm volume grows approximately linearly over seven days for all the shear stress values, with a growth rate that is inversely proportional to the wall shear stress. We develop a simple model of friction-limited growth, which agrees with the experimental observations. The model provides physical insight into growth mechanisms and can be used to develop accurate continuum models of bacterial biofilm growth.
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| 31. |
- Yan, Hongji, et al.
(författare)
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Glyco-Modification of Mucin Hydrogels to Investigate Their Immune Activity
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:17, s. 19324-19336
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Tidskriftsartikel (refereegranskat)abstract
- Mucins are multifunctional glycosylated proteins that are increasingly investigated as building blocks of novel biomaterials. An attractive feature is their ability to modulate the immune response, in part by engaging with sialic acid binding receptors on immune cells. Once assembled into hydrogels, bovine submaxillary mucins (Muc gels) were shown to modulate the recruitment and activation of immune cells and avoid fibrous encapsulation in vivo. However, nothing is known about the early immune response to Muc gels. This study characterizes the response of macrophages, important orchestrators of the material-mediated immune response, over the first 7 days in contact with Muc gels. The role of mucin-bound sialic acid sugar residues was investigated by first enzymatically cleaving the sugar and then assembling the mucin variants into covalently cross-linked hydrogels with rheological and surface nanomechanical properties similar to nonmodified Muc gels. Results with THP-1 and human primary peripheral blood monocytes derived macrophages showed that Muc gels transiently activate the expression of both pro-inflammatory and anti-inflammatory cytokines and cell surface markers, for most makers with a maximum on the first day and loss of the effect after 7 days. The activation was sialic acid-dependent for a majority of the markers followed. The pattern of gene expression, protein expression, and functional measurements did not strictly correspond to M1 or M2 macrophage phenotypes. This study highlights the complex early events in macrophage activation in contact with mucin materials and the importance of sialic acid residues in such a response. The enzymatic glyco-modulation of Muc gels appears as a useful tool to help understand the biological functions of specific glycans on mucins which can further inform on their use in various biomedical applications.
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| 32. |
- Yan, Hongji, et al.
(författare)
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Immune-Informed Mucin Hydrogels Evade Fibrotic Foreign Body Response In Vivo
- 2019
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Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028.
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Tidskriftsartikel (refereegranskat)abstract
- The immune-mediated foreign body response to biomaterial implants can trigger the formation of insulating fibrotic capsules that can compromise implant function. To address this challenge, the intrinsic bioactivity of the mucin biopolymer, a heavily glycosylated protein that forms the protective mucus gel covering mucosal epithelia, is leveraged. By using a bioorthogonal inverse electron demand Diels-Alder reaction, mucins are crosslinked into implantable hydrogels. It is shown that mucin hydrogels (Muc-gels) modulate the immune response driving biomaterial-induced fibrosis. Muc-gels do not elicit fibrosis 21 days after implantation in the peritoneal cavity of C57Bl/6 mice, whereas medical-grade alginate hydrogels are covered by fibrous tissues. Further, Muc-gels dampen the recruitment of innate and adaptive immune cells to the gel and trigger a pattern of very mild activation marked by a noticeably low expression of the fibrosis-stimulating transforming growth factor beta 1 cytokine. Macrophages recruited to Muc-gels upregulate the gene expression of the protein inhibitor of activated STAT 1 (PIAS1) and SH2-containing phosphatase 1 (SHP-1) cytokine regulatory proteins, which likely contributes to their low cytokine expression profiles. With this advance in mucin materials, an essential tool is provided to better understand mucin bioactivities and to initiate the development of new mucin-based and mucin-inspired "immune-informed" materials for implantable devices subject to fibrotic encapsulation.
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| 33. |
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| 34. |
- Yan, Hongji, et al.
(författare)
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Reversible Condensation of Mucins into Nanoparticles
- 2018
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Ingår i: Langmuir. - : AMER CHEMICAL SOC. - 0743-7463 .- 1520-5827. ; 34:45, s. 13615-13625
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Tidskriftsartikel (refereegranskat)abstract
- Mucins are high molar mass glycoproteins that assume an extended conformation and can assemble into mucus hydrogels that protect our mucosal epithelium. In nature, the challenging task of generating a mucus layer, several hundreds of micrometers in thickness, from micrometer-sized cells is elegantly solved by the condensation of mucins inside vesicles and their on-demand release from the cells where they suddenly expand to form the extracellular mucus hydrogel. We aimed to recreate and control the process of compaction for mucins, the first step toward a better understanding of the process and creating biomimetic in vivo delivery strategies of macromolecules. We found that by adding glycerol to the aqueous solvent, we could induce drastic condensation of purified mucin molecules, reducing their size by an order of magnitude down to tens of nanometers in diameter. The condensation effect of glycerol was fully reversible and could be further enhanced and partially stabilized by cationic cross-linkers such as calcium and polylysine. The change of structure of mucins from extended molecules to nano-sized particles in the presence of glycerol translated into macroscopic rheological changes, as illustrated by a dampened shear-thinning effect with increasing glycerol concentration. This work provides new insight into mucin condensation, which could lead to new delivery strategies mimicking cell release of macromolecules condensed in vesicles such as mucins and heparin.
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| 35. |
- Yilmaz Turan, Secil, et al.
(författare)
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Enzymatic production of hydrogels from corn bran feruloylated arabinoxylan with protective effects against reactive oxygen species
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The feruloylated nature of cereal bran arabinoxylans (AX) enables the production of strong hydrogen networks to be used as matrices for food and biomedical applications with protective effects against reactive oxygen species. Here we comparatively examine the physicochemical properties and radical scavenging activity of hydrogels developed from corn bran AX with high ferulic acid content following enzymatic crosslinking by laccase and peroxidase. Both enzymatic systems resulted in strong hydrogels with distinct kinetics, properties and ultrastructure. Peroxidase-mediated crosslinking exhibited much faster kinetics during hydrogel formation, whereas laccase-crosslinking provided a stronger network. Structural characterization by size exclusion chromatography, small angle X-ray scattering, and microscopy revealed that laccase formed aggregates with higher clustering strength, while peroxidase led to the occurrence of larger covalent polymer aggregates. As a proof of concept, we demonstrated that the AXhydrogels had adequate biocompatibility and demonstrated protective effects against oxidative stress on colon cells under in vitro conditions. The peroxidase-crosslinked hydrogel achieved a higher antioxidative effect. This study demonstrates the distinct effect of enzymatic crosslinking routes of highly feruloylated AX, resulting in hydrogels with tailored morphological, structural and rheological properties. Moreover, the AX hydrogels display excellent radical scavenging activity against cellular oxidative stress, which constitutes a proof of concept for their potential application in cell delivery, encapsulation and bio-fabrication.
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| 36. |
- Yilmaz Turan, Secil, et al.
(författare)
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Hydrogels with protective effects against cellular oxidative stress via enzymatic crosslinking of feruloylated arabinoxylan from corn fibre
- 2022
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 24:23, s. 9114-9127
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Tidskriftsartikel (refereegranskat)abstract
- Biocatalytical upgrading of side streams from agricultural biomass into multifunctional materials constitutes a very attractive option to increase the circularity of food and material systems. We propose the design of radical scavenging hydrogels with mechanical integrity and protective effects against reactive oxygen species by enzymatic crosslinking of arabinoxylans (AX) with high ferulic acid content extracted from corn fibre using subcritical water. We have compared the influence of two enzymatic systems, laccase/O-2 and peroxidase/H2O2, on the biochemical structure, multiscale assembly, physicochemical properties, and radical scavenging activity of the polysaccharide hydrogels. Peroxidase crosslinking results in instant hydrogel formation, whereas laccase shows slower crosslinking kinetics, resulting in a more elastic gel network. Characterization by size exclusion chromatography, small angle X-ray scattering, and microscopy revealed structural differences in the network organization of the hydrogels produced by the two enzymes. Laccase crosslinking leads to smaller polymeric aggregates, promoting their progressive organization in network clusters that impact the overall ultrastructure. Conversely, the fast crosslinking induced by peroxidase results in higher porosity and forms larger and potentially more heterogeneous aggregates, which seem to hinder their subsequent association in clusters. Both AX hydrogels exhibit adequate biocompatibility and protective effects against in vitro cellular oxidative stress compared to an alginate reference. This constitutes a proof of concept of the potential application of radical scavenging hydrogels from agricultural side streams for biomedical and nutritional applications in wound healing, cellular repair and targeted delivery.
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| 37. |
- Zhao, Juzhi, et al.
(författare)
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A novel 4D cell culture mimicking stomach peristalsis altered gastric cancer spheroids growth and malignance
- 2021
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Ingår i: Biofabrication. - : IOP Publishing. - 1758-5082 .- 1758-5090. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- In vitro cancer models that can largely mimic the in vivo microenvironment are crucial for conducting more accurate research. Models of three-dimensional (3D) culture that can mimic some aspects of cancer microenvironment or cancer biopsies that can adequately represent tumor heterogeneity are intensely used currently. Those models still lack the dynamic stress stimuli in gastric carcinoma exposed to stomach peristalsis in vivo. This study leveraged a lab-developed four-dimensional (4D) culture model by a magnetic responsive alginate-based hydrogel to rotating magnets that can mimic stress stimuli in gastric cancer (GC). We used the 4D model to culture human GC cell line AGS and SGC7901, cells at the primary and metastasis stage. We revealed the 4D model altered the cancer cell growth kinetics mechanistically by altering PCNA and p53 expression compared to the 3D culture that lacks stress stimuli. We found the 4D model altered the cancer spheroids stemness as evidenced by enhanced cancer stem cells (CD44) marker expression in AGS spheroids but the expression was dampened in SGC7901 cells. We examined the multi-drug resistance (MDR1) marker expression and found the 4D model dampened the MDR1 expression in SGC7901 cell spheroids, but not in spheroids of AGS cells. Such a model provides the stomach peristalsis mimic and is promising for conducting basic or translational GC-associated research, drug screening, and culturing patient gastric biopsies to tailor the therapeutic strategies in precision medicine.
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