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- Ferraris, Sara, et al.
(författare)
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Chemical, mechanical and antibacterial properties of silver nanocluster/silica composite coated textiles for safety systems and aerospace applications
- 2014
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 317, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the chemical, mechanical and antibacterial properties of a novel silver nanocluster/silica composite coating, obtained by sputtering, on textiles for use in nuclear bacteriological and chemical (NBC) protection suites and for aerospace applications.The properties of the coated textiles were analyzed in terms of surface morphology, silver concentration and silver release in artificial sweat and synthetic tap water, respectively. No release of silver nanoparticles was observed at given conditions.The water repellency, permeability, flammability and mechanical resistance of the textiles before and after sputtering demonstrated that the textile properties were not negatively affected by the coating.The antibacterial effect was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus and compared with the behavior of uncoated textiles.The coating process conferred all textiles a good antibacterial activity. Optimal deposition conditions were elaborated to obtain sufficient antibacterial action without altering the aesthetical appearance of the textiles.The antibacterial coating retained its antibacterial activity after one cycle in a washing machine only for the Nylon based textile.
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| 2. |
- Hulander, Mats, et al.
(författare)
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Blood interactions with noble metals: coagulation and immune complement activation.
- 2009
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Ingår i: ACS applied materials & interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 1:5, s. 1053-62
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Tidskriftsartikel (refereegranskat)abstract
- Noble metals are interesting biomaterials for a number of reasons, e.g., their chemical inertness and relative mechanical softness, silver's long known antimicrobial properties, and the low allergenic response shown by gold. Although important for the final outcome of biomaterials, little is reported about early events between pure noble metals and blood. In this article, we used whole blood in the "slide chamber model" to study the activation of the immune complement activation, generation of thrombin/antithrombin (TAT) complexes, and platelet depletion from blood upon contact with silver (Ag), palladium (Pd), gold (Au), titanium (Ti), and Bactiguard, a commercial nanostructured biomaterial coating comprised of Ag, Pd, and Au. The results show the highest TAT generation and platelet depletion on Ti and Au and lower on Pd, Ag, and the Bactiguard coating. The immune complement factor 3 fragment (C3a) was generated by the surfaces in the following order: Ag > Au > Pd > Bactiguard > Ti. Quartz crystal microbalance adsorption studies with human fibrinogen displayed the highest deposition to Ag and the lowest onto the Bactiguard coating. The adsorbed amounts of fibrinogen did not correlate with thrombogenicity in terms of TAT formation and platelet surface accumulation in blood. The combined results suggest, hence, that noble metal chemistry has a different impact on the protein adsorption properties and general blood compatibility. The low thrombogenic response by the Bactiguard coating cannot be explained by any of the single noble metal properties but is likely a successful combination of the nanostructure, nanogalvanic effects, or combinatory chemical and physical materials properties.
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| 3. |
- Hulander, Mats, et al.
(författare)
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Immune complement activation is attenuated by surface nanotopography
- 2011
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Ingår i: International Journal of Nanomedicine. - 1176-9114 .- 1178-2013. ; 6, s. 2653-2666
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Tidskriftsartikel (refereegranskat)abstract
- The immune complement (IC) is a cell-free protein cascade system, and the first part of the innate immune system to recognize foreign objects that enter the body. Elevated activation of the system from, for example, biomaterials or medical devices can result in both local and systemic adverse effects and eventually loss of function or rejection of the biomaterial. Here, the researchers have studied the effect of surface nanotopography on the activation of the IC system. By a simple nonlithographic process, gold nanoparticles with an average size of 58 nm were immobilized on a smooth gold substrate, creating surfaces where a nanostructure is introduced without changing the surface chemistry. The activation of the IC on smooth and nanostructured surfaces was viewed with fluorescence microscopy and quantified with quartz crystal microbalance with dissipation monitoring in human serum. Additionally, the ability of pre-adsorbed human immunoglobulin G (IgG) (a potent activator of the IC) to activate the IC after a change in surface hydrophobicity was studied. It was found that the activation of the IC was significantly attenuated on nanostructured surfaces with nearly a 50% reduction, even after pre-adsorption with IgG. An increase in surface hydrophobicity blunted this effect. The possible role of the curvature of the nanoparticles for the orientation of adsorbed IgG molecules, and how this can affect the subsequent activation of the IC, are discussed. The present findings are important for further understanding of how surface nanotopography affects complex protein adsorption, and for the future development of biomaterials and blood-contacting devices.
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| 4. |
- Ohrlander, Mattias
(författare)
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Modification of stable and degradable polymers by heterogeneous grafting
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis summarizes the investigations of the electronbeam initiated grafting of a hydrophilic monomer, acrylamide(AAm), onto three polymers; linear low density poly(ethylene)(LLDPE), poly(&-caprolactone) (PCL) and chemicallycrosslinked poly( 1,5-dioxepan-2-one) (PDXO-X). LLDPE and PCLare semicrystalline and PDXO-X is fully amorphous. Both PCL andPDXO-X contain a hydrolysis sensitive ester bond in therepeating unit and are considered as biodegradable substrateswhile LLDPE is stable. The solid polymeric substrates areelectron beam irradiated prior to immersion in a liquid phasecontaining the monomer. Graft initiation, propagation andterrnination Will then occur in a heterogeneous phase system.The main goal with this work is to obtain new knowledge of somefundamental properties and potential applications for theheterogeneous grafting.The first part concems the influence of EB radiation onLLDPE, PCL and PDXO-X. The aim was to identify the initiatingspecies in the polymers using electron spin resonance andluminescence analyses. The cross linking and/or chain scissionin the polymer matrix, as a result of the EB irradiation, wasanalyzed. It was found that EB irradiation of PCL in inertatmosphere (argon) generated secondary alkylether radieals.This type of radieal was also found in PCL irradiated in airtogether with peroxy radieals. Chain scission was found to bethe dominating reaction in PCL as a result of the irradiation.The EB irradiation of PDXO-X in argon and air generatedtertiary carbon centered radieals. However, no peroxy radiealscould be detected for PDXO-X irradiated in air. Swellingmeasurements and SEC analysis of the soluble fraction suggeststhat chain scission is the main reaction in PDXO-X as a resultof the EB irradiation.The second part investigates the morphology of the graftedpolymer matrix, using LLDPE as model material. It also coversthe AAm grafting onto PCL, mainly evaluating the effect of doseand added inhibitor (Mohr's salt) upon gti yield (GY), andchain length of the grafted poly(acry1 amide) (PAAm). In thecase of the grafting of AAm onto LLDPE it is suggested that theinitiation occurs mainly in the semi-ordered interphase alongwith a decrease in crystallinity, due to solubilization of theordered crystalline domains. The grafted PAAm chains were foundto be more branthed than that of a ungrafted PAAm referencematerial. This is explained by that the chain growth of PAAmoccurs in the interphase where the toncentration of radieals,originating from the crystalline phase and from growing chainends, is high, hence promoting chain transfer reactions.The third part investigates the degradation of a system witha hydrophilic polymer (AAm) surface grafted onto the morehydrophobic PCL and PDXO-X. For PCL, no differente indegradation behavior could be obset-ved between irradiatedmaterials and irradiated and grafted materials. In the case ofPDXO-X, a significant decrease in degradation time was observedfor theirradiated and surface grafted sarnple as compared tothe irradiated sample.In the fourth part, derivatization of grafted PAArn topoly(viny1 amine) by the Hofmann degradation is examined. Theprimary amines were used for the coupling of heparin onto LLDPEand the surface activity towards arttimrombin III (AT III) wastested. The heparinized surfaces had a low but significantuptake of AT III and no activation of FXTI could bedetected.
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| 5. |
- Suska, Felicia, 1974, et al.
(författare)
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In vivo evaluation of noble metal coatings
- 2010
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Ingår i: Journal of Biomedical Materials Research Part B: Applied Biomaterials. - 1552-4981. ; 92B:1, s. 86-94
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Tidskriftsartikel (refereegranskat)abstract
- A nanotopographic noble metal (Ag, Au, Pd) coating has been applied on commercial urinary catheters and used in more than 80,000 patients, with good clinical results. We have previously evaluated the biocompatibility of different variations of this coating, showing high cellular viability and function in vitro. However, the reasons for good clinical and preclinical behavior are not known. This in vivo study aimed to investigate the soft tissue peri-implant reaction to five coatings with systematically altered noble metal ratios after 1, 3, and 21 days of implantation in rats. The results show that coatings of silver only, or silver with medium amounts of gold and low-medium palladium content were superior to other tested coatings. Such surfaces were during the first days after implantation associated with a decreased recruitment of inflammatory cells to implant close exudates, a lower percentage of neutrophils, higher cell viability, and lower production of monocyte chemoattractant protein-1 (MCP-1), compared to the other coatings and uncoated silicone (PDMS) control. In contrast, the addition of higher concentrations of gold and palladium to silver induced a thicker soft tissue capsule. Coatings with high concentration of palladium induced the thickest fibrouscapsule after 21 days of implantation. The study demonstrates that by varying the noble metal ratio at implant surfaces it is possible to modulate inflammation and fibrosis in soft tissue.
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| 12. |
- Svensson, Sara, 1981, et al.
(författare)
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Osseointegration of titanium with an antimicrobial nanostructured noble metal coating
- 2013
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Ingår i: Nanomedicine: Nanotechnology, Biology, and Medicine. - : Elsevier BV. - 1549-9634 .- 1549-9642. ; 9:7, s. 1048-1056
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Tidskriftsartikel (refereegranskat)abstract
- Nanometer scale surface features on implants and prostheses can potentially be used to enhance osseointegration and may also add further functionalities, such as infection resistance, to the implant. In this study, a nanostructured noble metal coating consisting of palladium, gold and silver, never previously used in bone applications, was applied to machined titanium screws to evaluate osseointegration after 6 and 12. weeks in rabbit tibiae and femurs. Infection resistance was confirmed by in vitro adhesion test. A qualitatively and quantitatively similar in vivo bone response was observed for the coated and uncoated control screws, using histology, histomorphometry and electron microscopy. The bone-implant interface analysis revealed an extensive bone formation and direct bone-implant contact. These results demonstrate that the nanostructured noble metal coating with antimicrobial properties promotes osseointegration and may therefore be used to add extra implant functionality in the form of increased resistance to infection without the use of antibiotics. From the Clinical Editor: The authors of this paper demonstrate that nanostructured noble metal coating of implants and prostheses used in orthopedic procedures promotes osseointegration and may be used to add extra implant functionality in the form of increased resistance to infection without the use of antibiotics.
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