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Yla-Soininmaki A.,University of Turku | Moritz N.,University of Turku | Moritz N.,Biocity Turku Biomaterials Research Program | Lassila L.V.J.,University of Turku | And 3 more authors.
Journal of Materials Science: Materials in Medicine | Year: 2013

The aim of this study was to characterize the microstructure and mechanical properties of porous fiber-reinforced composites (FRC). Implants made of the FRC structures are intended for cranial applications. The FRC specimens were prepared by impregnating E-glass fiber sheet with non-resorbable bifunctional bis-phenyl glycidyl dimethacrylate and triethylene glycol dimethacrylate resin matrix. Four groups of porous FRC specimens were prepared with a different amount of resin matrix. Control group contained specimens of fibers, which were bound together with sizing only. Microstructure of the specimens was analyzed using a micro computed tomography (micro-CT) based method. Mechanical properties of the specimens were measured with a tensile test. The amount of resin matrix in the specimens had an effect on the microstructure. Total porosity was 59.5 % (median) in the group with the lowest resin content and 11.2 % (median) in the group with the highest resin content. In control group, total porosity was 94.2 % (median). Correlations with resin content were obtained for all micro-CT based parameters except TbPf. The tensile strength of the composites was 21.3 MPa (median) in the group with the highest resin content and 43.4 MPa (median) in the group with the highest resin content. The tensile strength in control group was 18.9 MPa (median). There were strong correlations between the tensile strength of the specimens and most of the micro-CT based parameters. This experiment suggests that porous FRC structures may have the potential for use in implants for cranial bone reconstructions, provided further relevant in vitro and in vivo tests are performed. © 2013 Springer Science+Business Media New York. Source

Vuorinen A.-M.,University of Turku | Vuorinen A.-M.,Biocity Turku Biomaterials Research Program | Dyer S.R.,Oregon Health And Science University | Lassila L.V.J.,University of Turku | And 3 more authors.
Composite Interfaces | Year: 2011

Objectives: The aim of this study was to find a way to adhere dimethacrylate-resin to poly(paraphenylene) based rigid rod polymer (RRP) substrate. Methods: The effect of resin dissolving time on RRP substrate and effect of different surface treatments were tested in this study. Tested surface treatments contained solvent dichloromethane (DCM) based primers or additional treatment at an increased temperature of the substrate. Shear bond strength test and scanning electron microscope (SEM) analyses were chosen for test methods. Results: Results confirmed that by increasing the dissolving time of resin on the surface of RRP substrate the bond strengths increased (ANOVA p < 0.05). Temperature increase at the substrate increased bond strength (p < 0.05). Of the solvent DCM based primers, the primer which contained dimethacrylate-resin and dissolved RRP increased bond strength (p < 0.05). SEM evaluation suggested that the reason for the increased bond strengths was related to the alteration of the RRP substrate's bonding surface. Significance: Within the limitations of this study it can be concluded that improved adhesion between dimethacrylate-resin and poly(paraphenylene) based RRP was possible to obtain. © 2011 Koninklijke Brill NV, Leiden. Source

Rekola J.,University of Turku | Rekola J.,Biocity Turku Biomaterials Research Program | Lassila L.V.J.,University of Turku | Lassila L.V.J.,Biocity Turku Biomaterials Research Program | And 10 more authors.
Bio-Medical Materials and Engineering | Year: 2014

BACKGROUND: Wood has been used as a model material for the development of novel fiber-reinforced composite bone substitute biomaterials. In previous studies heat treatment of wood was perceived to significantly increase the osteoconductivity of implanted wood material. AIM: The objective of this study was to examine some of the changing attributes of wood materials that may contribute to improved biological responses gained with heat treatment. METHODS: Untreated and 140°C and 200°C heat-treated downy birch (Betula pubescens Ehrh.) were used as the wood materials. Surface roughness and the effect of pre-measurement grinding were measured with contact and non-contact profilometry. Liquid interaction was assessed with a dipping test using two manufactured liquids (simulated blood) as well as human blood. SEM was used to visualize possible heat treatment-induced changes in the hierarchical structure of wood. RESULTS: The surface roughness was observed to significantly decrease with heat treatment. Grinding methods had more influence on the surface contour and roughness than heat treatment. The penetration of the human blood in the 200°C heat-treated exceeded that in the untreated and 140°C heat-treated materials. SEM showed no significant change due to heat treatment in the dry-state morphology of the wood. DISCUSSION: The results of the liquid penetration test support previous findings in literature concerning the effects of heat treatment on the biological response to implanted wood. Heat-treatment has only a marginal effect on the surface contour of wood. The highly specialized liquid conveyance system of wood may serve as a biomimetic model for the further development of tailored fiber-composite materials. © 2014 - IOS Press and the authors. Source

Nganga S.,University of Turku | Nganga S.,Biocity Turku Biomaterials Research Program | Travan A.,University of Trieste | Marsich E.,University of Trieste | And 8 more authors.
Journal of Materials Science: Materials in Medicine | Year: 2013

Biostable fiber-reinforced composite (FRC) implants prepared from bisphenol-A-dimethacrylate and triethyleneglycoldimethacrylate resin reinforced with E-glass fibers have been successfully used in cranial reconstructions in 15 patients. Recently, porous FRC structures were suggested as potential implant materials. Compared with smooth surface, porous surface allows implant incorporation via bone ingrowth, but is also a subject to bacterial attachment. Non-cytotoxic silver-polysaccharide nanocomposite coatings may provide a way to decrease the risk of bacterial contamination of porous FRC structures. This study is focused on the in vitro characterization of the effect porosity on the antimicrobial efficiency of the coatings against Staphylococcus aureus and Pseudomonas aeruginosa by a series of microbiological tests (initial adhesion, antimicrobial efficacy, and biofilm formation). Characterization included confocal laser scanning microscopy and scanning electron microscopy. The effect of porosity on the initial attachment of S. aureus was pronounced, but in the case of P. aeruginosa the effect was negligible. There were no significant effects of the coatings on the initial bacterial attachment. In the antimicrobial efficacy test, the coatings were potent against both strains regardless of the sample morphology. In the biofilm tests, there were no clear effects either of morphology or of the coating. Further coating development is foreseen to achieve a longer-term antimicrobial effect to inhibiting bacterial implant colonization. © 2013 Springer Science+Business Media New York. Source

Nganga S.,University of Turku | Nganga S.,Biocity Turku Biomaterials Research Program | Moritz N.,University of Turku | Moritz N.,Biocity Turku Biomaterials Research Program | And 11 more authors.
Biofabrication | Year: 2014

Biostable fiber-reinforced composites, based on bisphenol-A-dimethacrylate and triethyleneglycoldimethacrylate thermoset polymer matrix reinforced with E-glass fibers have been successfully used in cranial reconstructions and the material has been approved for clinical use. As a further refinement of these implants, antimicrobial, non-cytotoxic coatings on the composites were created by an immersion procedure driven by strong electrostatic interactions. Silver nanoparticles (nAg) were immobilized in lactose-modified chitosan (Chitlac) to prepare the bacteriostatic coatings. Herein, we report the use of inkjet technology (a drop-on-demand inkjet printer) to deposit functional Chitlac-nAg coatings on the thermoset substrates. Characterization methods included scanning electron microscopy, scanning white light interferometry and electro-thermal atomic absorption spectroscopy. Inkjet printing enabled the fast and flexible functionalization of the thermoset surfaces with controlled coating patterns. The coatings were not impaired by the printing process: the kinetics of silver release from the coatings created by inkjet printing and conventional immersion technique was similar. Further research is foreseen to optimize printing parameters and to tailor the characteristics of the coatings for specific clinical applications. © 2014 IOP Publishing Ltd. Source

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