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- Aguilar Sánchez, Andrea, 1987-
(författare)
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Nanopolysaccharide coatings for functional surfaces in water-treatment materials : From mechanisms to process scalability
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, materials from renewable resources were used to develop functionalized surfaces for water treatment. The work is thus inspired by, and contributes to, the United Nations sustainable goals of: (i) clean water and sanitation, (ii) climate action, (iii) responsible consumption and production, (iv) life below water, and (v) partnerships for the goals.Nanopolysaccharides, most specifically nanocellulose and nanochitin, are great candidates for functional and renewable materials for multiple applications, including the treatment of water and wastewater. This thesis focused on the formulation of different types of nanopolysaccharide-based coatings to enhance the performance of commercially available membranes and cellulose fabrics. We developed a simple waterborne layer-by-layer cellulose nanocrystals (CNC) and TEMPO-oxidized cellulose nanofibrils (T-CNF) coating for commercially available membranes. By changing the surface and pore structure of the membrane, the coating tuned which substrates could pass through the membrane, improved antifouling performanced, and when derived from T-CNF, it was harmful to bacterial colonization. Considering the observed T-CNF’s effect on bacteria, we developed a chemically crosslinked T-CNF/Poly(vinyl) alcohol (PVA) coating with outstanding antibiofouling performance, ion adsorption/rejection combined with size exclusion, and with dimensional and pH stability. Furthermore, we used a surface-impregnation approach based on bio-based nanotechnology which resulted in highly efficient, with improved mechanical properties, and fully bio-based high-flux water filtration membranes using commercially available nonwoven fabrics. Membranes with coatings prepared from CNC, chitin nanocrystals (ChNC) and T-CNF separated particles in the size range of bacteria and viruses, and those prepared from also T-CNF showed high microplastic filtration efficiency. Moreover, membrane coating based on ChNC and T-CNF had outstanding antibacterial properties.Overall, we demonstrated that nanopolysaccharide coatings on membranes could provide a significant reduction in organic fouling and biofilm formation while enabling the adsorption of ions and separation of microplastics. In the case of biofilm formation, the functional group and surface charge of the different nanopolysaccharides determined the effect over bacteria, indicating that surfaces could be tailored against microbes. In addition, we directly compared the effect of the different nanopolysaccharides of interest (CNC, T-CNF, ligno-celullose nanocrystals (L-CNC), and ChNC) on bacterial viability and biofilm formation, and found a great difference between the different types of nanocellulose and a different mechanism for nanochitin. Thorough, none of the nanopolysaccharides displayed cytotoxic effects while in indirect contact with the bacterial cells. Nevertheless, T-CNF, ChNC and L-CNC showed a cytostatic effect on bacterial proliferation. Furthermore, the nanomechanical properties of the bacterial cells and interacting forces between the nanopolysaccharides and Escherichia coli (E. coli) were affected when in direct contact with the nanopolysaccharide surfaces.Lastly, we upscaled one of our coating processes, demonstrating that the method could be easily implemented at an industrial level. The impact of this thesis relies on the effectiveness of the coatings, the different types of functionalities observed, the demonstrated fast implementation at an industrial scale, and the potential to extrapolate this technology to other applications.
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| 2. |
- Asper, M., et al.
(författare)
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Removal of xenotropic murine leukemia virus by nanocellulose based filter paper
- 2015
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Ingår i: Biologicals (Print). - : Elsevier BV. - 1045-1056 .- 1095-8320. ; 43:6, s. 452-456
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Tidskriftsartikel (refereegranskat)abstract
- The removal of xenotrpic murine leukemia virus (xMuLV) by size-exclusion filter paper composed of 100% naturally derived cellulose was validated. The filter paper was produced using cellulose nanofibers derived from Cladophora sp. algae. The filter paper was characterized using atomic force microscopy, scanning electron microscopy, helium pycnometry, and model tracer (100 nm latex beads and 50 nm gold nanoparticles) retention tests. Following the filtration of xMuLV spiked solutions, LRV >= 5.25 log(10) TCID50 was observed, as limited by the virus titre in the feed solution and sensitivity of the tissue infectivity test. The results of the validation study suggest that the nanocellulose filter paper is useful for removal of endogenous rodent retroviruses and retrovirus-like particles during the production of recombinant proteins.
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| 3. |
- Brohede, Ulrika, et al.
(författare)
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A novel graded bioactive high adhesion implant coating
- 2009
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 255:17, s. 7723-7728
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Tidskriftsartikel (refereegranskat)abstract
- One method to increase the clinical success rate of metal implants is to increase their bone bonding properties, i.e. to develop a bone bioactive surface leading to reduced risks of interfacial problems. Much research has been devoted to modifying the surface of metals to make them become bioactive. Many of the proposed methods include depositing a coating on the implant. However, there is a risk of coating failure due to low substrate adhesion. This paper describes a method to obtain bioactivity combined with a high coating adhesion via a gradient structure of the coating. Gradient coatings were deposited on Ti (grade 5) using reactive magnetron sputtering with increasing oxygen content. To increase the grain size in the coating, all coatings were post annealed at 385 degrees C. The obtained coating exhibited a gradual transition over 70 nm from crystalline titanium oxide (anatase) at the surface to metallic Ti in the substrate, as shown using cross-section transmission electron microscopy and X-ray photoelectron spectroscopy depth pro. ling. Using scratch testing, it could be shown that the adhesion to the substrate was well above 1 GPa. The bioactivity of the coating was verified in vitro by the spontaneous formation of hydroxylapatite upon storage in phosphate buffer solution at 37 degrees C for one week. The described process can be applied to implants irrespective of bulk metal in the base and should introduce the possibility to create safer permanent implants like reconstructive devices, dental, or spinal implants.
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| 5. |
- Brohede, Ulrika, et al.
(författare)
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Multifunctional implant coatings providing possibilities for fast antibiotics loading with subsequent slow release
- 2009
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 20:9, s. 1859-1867
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to fast-load biomimetic hydroxyapatite coatings on surgical implant with the antibiotics Amoxicillin, Gentamicin sulfate, Tobramycin and Cephalothin has been investigated in order to develop a multifunctional implant device offering sustained local anti-bacterial treatment and giving the surgeon the possibility to choose which antibiotics to incorporate in the implant at the site of surgery. Physical vapor deposition was used to coat titanium surfaces with an adhesion enhancing gradient layer of titanium oxide having an amorphous oxygen poor composition at the interface and a crystalline bioactive anatase TiO2 composition at the surface. Hydroxyapatite (HA) was biomimetically grown on the bioactive TiO2 to serve as a combined bone in-growth promoter and drug delivery vehicle. The coating was characterized using scanning and transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The antibiotics were loaded into the HA coatings via soaking and the subsequent release and antibacterial effect were analyzed using UV spectroscopy and examination of inhibition zones in a Staphylococcus aureus containing agar. It was found that a short drug loading time of 15 min ensured antibacterial effects after 24 h for all antibiotics under study. It was further found that the release processes of Cephalothin and Amoxicillin consisted of an initial rapid drug release that varied unpredictably in amount followed by a reproducible and sustained release process with a release rate independent of the drug loading times under study. Thus, implants that have been fast-loaded with drugs could be stored for ~10 min in a simulated body fluid after loading to ensure reproducibility in the subsequent release process. Calculated release rates and measurements of drug amounts remaining in the samples after 22 h of release indicated that a therapeutically relevant dose could be achieved close to the implant surface for about 2 days. Concluding, the present study provides an outline for the development of a fast-loading slow-release surgical implant kit where the implant and the drug are separated when delivered to the surgeon, thus constituting a flexible solution for the surgeon by offering the choice of quick addition of antibiotics to the implant coating based on the patient need.
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| 7. |
- Carlsson, Daniel O., et al.
(författare)
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Aspirin degradation in surface-charged TEMPO-oxidized mesoporous crystalline nanocellulose
- 2013
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 461:1-2, s. 74-81
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Tidskriftsartikel (refereegranskat)abstract
- TEMPO-mediated surface oxidation of mesoporous highly crystalline Cladophora cellulose was used to introduce negative surface charges onto cellulose nanofibrils without significantly altering other structural characteristics. This enabled the investigation of the influence of mesoporous nanocellulose surface charges on aspirin chemical stability to be conducted. The negative surface charges (carboxylate content 0.44 ± 0.01 mmol/g) introduced on the mesoporous crystalline nanocellulose significantly accelerated aspirin degradation, compared to the starting material which had significantly less surface charge (0.06 ± 0.01 mmol/g). This effect followed from an increased aspirin amorphisation ability in mesopores of the oxidized nanocellulose. These results highlight the importance of surface charges in formulating nanocellulose for drug delivery.
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