| 1. |
- Bougas, Kostas, et al.
(författare)
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Bone apposition to laminin-1 coated implants : Histologic and 3D evaluation
- 2013
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Ingår i: International Journal of Oral and Maxillofacial Surgery. - : Elsevier BV. - 0901-5027 .- 1399-0020. ; 42:5, s. 677-682
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Tidskriftsartikel (refereegranskat)abstract
- Laminin-1 has been reported as one of the factors responsible for the nucleation of calcium phosphates and, in vitro, has been reported to selectively recruit osteoprogenitors. This article focused on its in vivo effects, and evaluated the effect of laminin-1 local application on osseointegration. Polished cylindrical hydroxyapatite implants were coated with laminin-1 (test) and the bone responses in the rabbit tibiae after 2 and 4 weeks were evaluated and compared to the non-coated implants (control). Before the samples were processed for histological sectioning, they were three-dimensionally analysed with micro computed tomography (μCT). Both evaluation methods were analysed with regards to bone area around the implant and bone to implant contact. From the histologic observation, new bone formation around the laminin-1 coated implant at 2 weeks seemed to have increased the amount of supporting bone around the implant, however, at 4 weeks, the two groups presented no notable differences. The two-dimensional and three-dimensional morphometric evaluation revealed that both histologic and three-dimensional analysis showed some tendency in favour of the test group implants, however there was no statistical significance between the test and control group results.
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| 2. |
- Breding, Karin, 1983, et al.
(författare)
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The Effect of Hydroxyapatite Nanocrystals on Osseointegration of Titanium Implants: An In Vivo Rabbit Study
- 2014
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Ingår i: International Journal of Dentistry. - : Hindawi Limited. - 1687-8736 .- 1687-8728. ; 2014, s. (article id) 171305-
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Tidskriftsartikel (refereegranskat)abstract
- Osseointegration is dependent on implant surface characteristics, including surface chemistry and topography. The presence of nanosized calcium phosphates on the implant surface is interesting to investigate since they affect both the nanotopography and surface chemistry, forming a bone mineral resembling surface. In this work, the osseointegration of titanium implants with and without the presence of hydroxyapatite (HA) nanocrystals has been evaluated in vivo. The integration was examined using removal torque measurements and real-time polymerase chain reaction (RT-PCR) analysis. The study was performed using two healing time points, 3 and 12 weeks. The results showed that the torque needed to remove the implants was insignificant between the non- and HA-coated implants, both at weeks 3 and 12. The RT-PCR, however, showed significant differences for osteoblast, osteoclast, and proinflammation markers when HA nanocrystals were present.
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| 3. |
- Bryington, M. S., et al.
(författare)
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The influence of nano hydroxyapatite coating on osseointegration after extended healing periods
- 2013
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Ingår i: Dental Materials. - : Elsevier BV. - 0109-5641 .- 1879-0097. ; 29:5, s. 514-520
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Studies observing early wound healing periods around dental implants demon-strate an implants ability to enhance osseointegration, the bone-implant interactions for extended healing periods though have not been thoroughly studied. Methods. Twenty threaded titanium alloy (Ti6Al4V, Grade 5) implants were inserted bilaterally, half prepared to impart stable hydroxyapatite nanoparticles onto a sand blasted and acid etched surface (HA) and half with a non-coated control surface with only heat treatment (HT), into eighteen rabbit femurs. At 12 weeks, the bone-implant blocks were retrieved for micro computed tomography (mu CT), histologic processing and histomorphometric evaluation. Results. The bone-to-implant contact for the entire threaded portion of the implant revealed 57.1% (21.0) for the HT group and 38.8% (17.7) for the HA group with a total bone area within the threads 72.5% (13.9) (HT) and 59.7% (12.5) (HA). The 3D reconstructed mu CT image corresponded to the histomorphometric results. Significance. It is suggested that multiple factors such as the change in topography and chemistry may have influenced the outcomes.
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| 4. |
- Fomalont, E. B., et al.
(författare)
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THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
- 2015
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 808:1
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Tidskriftsartikel (refereegranskat)abstract
- A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.
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| 5. |
- Hayashi, Mariko, et al.
(författare)
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In vitro characterization and osteoblast responses to nanostructured photocatalytic TiO2 coated surfaces.
- 2012
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 8:6, s. 2411-6
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the study were to characterize a nanostructured photoactive titanium dioxide (TiO(2)) coating and to compare the cellular response of human osteoblasts before and after ultraviolet (UV) irradiation of the coating. A specific nanostructured TiO(2) powder (Degussa P-25), which consists of approximately 80% anatase and 20% rutile, was spin-coated onto commercially pure titanium discs, and was heat-treated thereafter. After topographical, chemical and photocatalytic property characterizations, human osteoblasts were cultured on the coated discs before and after UV irradiation. Cell morphology was evaluated by scanning electron microscopy (SEM), and cell viability was analysed by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. From the contact angle analysis, the wettability significantly improved after UV irradiation. The cultured cells were flattened with numerous elongated lammellipodia; however, no morphological differences were indicated between -UV and +UV surfaces. The MTT assay analysis showed that -UV surface presented significantly higher viability compared to the +UV surface except for one cell population group at 3h where there were no differences. The nanostructured photoactive TiO(2) surface improved its hydrophilicity by UV irradiation, however no enhancing effect in cell response was confirmed at the time tested compared to the non-irradiated surface.
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| 6. |
- Hayashi, Mariko, et al.
(författare)
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Photocatalytically induced hydrophilicity influences bone remodelling at longer healing periods: a rabbit study
- 2014
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Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 25:6, s. 749-754
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesPreviously, we have reported that photocatalytically active hydrophilicity of the anatase titanium dioxide (TiO2) nanoparticles coated onto commercially pure titanium discs presented significantly improved hydrophilicity after ultraviolet irradiation. As hydrophilicity has shown enhancement of osseointegration, the in vivo responses were of great interest. The aim of this study was to evaluate whether or not the photo-activated hydrophilicity generated at the time of implant placement has an effect on the longer healing periods for osseointegration. Materials and methodsPhotocatatytically active nanostructured TiO2 powder (Degussa P-25), which consists of approximately 80% anatase and 20% rutile, was spin-coated onto commercially pure titanium discs and was heat-treated thereafter. These P25-coated discs were irradiated with ultraviolet (UV) light for the test (+UV) group, and non-irradiated discs were prepared for the control (-UV) group. Both groups of discs were placed in the rabbits' tibiae. After 12weeks of healing period, histological analysis and gene expression analysis using real-time RT-PCR were performed. ResultsFrom the histological analyses, there were no specific differences between -UV and +UV groups. However, from the gene expression analysis, ALP, RUNX-2 and IL-10 were significantly upregulated for the +UV group compared with the -UV group. ConclusionsThe biologically enhancing effect to photocatalytically activated surfaces remained even after 12weeks of healing time in terms of genetic responses.
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| 7. |
- He, Wenxiao, 1985, et al.
(författare)
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Osteogenesis-inducing calcium phosphate nanoparticle precursors applied to titanium surfaces
- 2013
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Ingår i: Biomedical Materials (Bristol). - : IOP Publishing. - 1748-605X .- 1748-6041. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effects of the morphology and physicochemical properties of calcium phosphate (CaP) nanoparticles on osteogenesis. Two types of CaP nanoparticles were compared, namely amorphous calcium phosphate (ACP) nano-spheres (diameter: 9-13 nm) and poorly crystalline apatite (PCA) nano-needles (30-50 nm x 2-4 nm) that closely resemble bone apatite. CaP particles were spin-coated onto titanium discs and implants; they were evaluated in cultured mouse calvarial osteoblasts, as well as after implantation in rabbit femurs. A significant dependence of CaP coatings was observed in osteoblast-related gene expression (Runx2, Colla1 and Spp1). Specifically, the PCA group presented an up-regulation of the osteospecific genes, while the ACP group suppressed the Runx2 and Colla1 expression when compared to blank titanium substrates. Both the ACP and PCA groups presented a more than three-fold increase of calcium deposition, as suggested by Alizarin red staining. The removal torque results implied a slight tendency in favour of the PCA group. Different forms of CaP nanostructures presented different biologic differences; the obtained information can be used to optimize surface coatings on biomaterials.
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| 8. |
- Jimbo, Ryo, et al.
(författare)
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Genetic Responses to Nanostructured Calcium-phosphate-coated Implants.
- 2011
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Ingår i: Journal of dental research. - : SAGE Publications. - 1544-0591 .- 0022-0345. ; 90:12, s. 1422-7
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured calcium phosphate (CaP) has been histologically and biomechanically proven to enhance osseointegration of implants; however, conventional techniques were not sufficiently sensitive to capture its biological effects fully. Here, we compared the conventional removal torque (RTQ) evaluation and gene expression in tissues around nanostructured CaP-coated implants, using real-time RT-PCR, with those of uncoated implants, in a rabbit model. At 2 wks, RTQ values were significantly higher, alkaline phosphatase (ALP) expression was significantly higher, and runt-related transcription factor 2 and tumor necrosis factor-α expressions were significantly lower in the coated than in the uncoated implants. This indicates that inflammatory responses were suppressed and osteoprogenitor activity increased around the CaP-coated surface. At 4 wks, although RTQ values did not significantly differ between the 2 groups, ALP and osteocalcin (OCN) were significantly up-regulated in the coated group, indicating progressive mineralization of the bone around the implant. Moreover, an osteoclast marker, adenosine triphosphatase, which indicates acidification of the resorption lacunae, was significantly higher for the coated implants, suggesting gradual resorption of the CaP coating. This study reveals detailed genetic responses to nanostructured CaP-coated implants and provides evidence that the effect of nanotopography is significant during the osseointegration cascade.
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| 9. |
- Jimbo, Ryo, 1979, et al.
(författare)
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Histological and three-dimensional evaluation of osseointegration to nanostructured calcium phosphate-coated implants.
- 2011
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Ingår i: Acta biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061.
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructures on implant surfaces have been shown to enhance osseointegration; however, commonly used evaluation techniques are probably not sufficiently sensitive to fully determine the effects of this process. This study aimed to observe the osseointegration properties of nanostructured calcium phosphate (CaP)-coated implants, by using a combination of three-dimensional imaging and conventional histology. Titanium implants were coated with stable CaP nanoparticles using an immersion technique followed by heat treatment. Uncoated implants were used as the control. After topographical and chemical characterizations, implants were inserted into the rabbit femur. After 2 and 4weeks, the samples were retrieved for micro-computed tomography and histomorphometric evaluation. Scanning electron microscopy evaluation indicated that the implant surface was modified at the nanoscale by CaP to obtain surface textured with rod-shaped structures. Relative to the control, the bone-to-implant contact for the CaP-coated implant was significantly higher at 4weeks after the implant surgery. Further, corresponding 3-D images showed active bone formation surrounding the implant. 3-D quantification and 2-D histology demonstrated statistical correlation; moreover, 3-D quantification indicated a statistical decrease in bone density in the non-coated control implant group between 2 and 4weeks after the surgery. The application of 3-D evaluation further clarified the temporal characteristics and biological reaction of implants in bone.
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| 10. |
- Jimbo, Ryo, et al.
(författare)
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Nano Hydroxyapatite-coated Implants Improve Bone Nanomechanical Properties
- 2012
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Ingår i: Journal of Dental Research. - : SAGE Publications. - 0022-0345 .- 1544-0591. ; 91:12, s. 1172-1177
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features; here we describe a nanoscale hydroxyapatite (HA)-coated implant surface and hypothesize that it will hasten osseointegration and improve its quality relative to that of non-coated implants. Twenty threaded titanium alloy implants, half prepared with a stable HA nanoparticle surface and half grit-blasted, acid-etched, and heat-treated (HT), were inserted into rabbit femurs. Pre-operatively, the implants were morphologically and topographically characterized. After 3 weeks of healing, the samples were retrieved for histomorphometry. The nanomechanical properties of the surrounding bone were evaluated by nanoindentation. While both implants revealed similar bone-to-implant contact, the nanoindentation demonstrated that the tissue quality was significantly enhanced around the HA-coated implants, validating the postulated hypothesis.
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| 11. |
- Karlsson, Johan, 1984, et al.
(författare)
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In vivo biomechanical stability of osseointegrating mesoporous TiO2 implants
- 2012
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 8:12, s. 4438-4446
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous materials are of high interest as implant coatings to receive an enhanced osseointegration. In this study, titanium implants coated with mesoporous TiO(2) thin films have been evaluated both in vitro and in vivo. Material characterization showed that, with partly crystalline TiO(2) (anatase), long-range-ordered hydrophilic mesoporous thin films with a pore size of 6nm were obtained. Evaluation of the mechanical resistance showed that the films were robust enough to withstand the standard implantation procedure. In vitro apatite formation was studied using simulated body fluids, showing that the pores are accessible for ions and that formation of apatite was increased due to the presence of the mesopores. An in vivo study using a rabbit model was executed in which the removal torque and histomorphometry were evaluated. The results show that the biomechanical stability of the TiO(2) coating was unaffected by the presence of mesopores and that osseointegration was achieved without any signs of inflammation.
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| 12. |
- Schwartz Filho, Humberto Osvaldo, et al.
(författare)
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The effect of laminin-1-doped nanoroughened implant surfaces : gene expression and morphological evaluation
- 2012
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Ingår i: International Journal of Biomaterials. - : Hindawi Publishing Corporation. - 1687-8787 .- 1687-8795. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- Aim. This study aimed to observe the morphological and molecular effect of laminin-1 doping to nanostructured implant surfaces in a rabbit model. Materials and Methods. Nanostructured implants were coated with laminin-1 (test; dilution, 100 μg/mL) and inserted into the rabbit tibiae. Noncoated implants were used as controls. After 2 weeks of healing, the implants were removed and subjected to morphological analysis using scanning electron microscopy (SEM) and gene expression analysis using the real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Results. SEM revealed bony tissue attachment for both control and test implants. Real-time RT-PCR analysis showed that the expression of osteoblast markers RUNX-2, osteocalcin, alkaline phosphatase, and collagen I was higher (1.62-fold, 1.53-fold, 1.97-fold, and 1.04-fold, resp.) for the implants modified by laminin-1 relative to the control. All osteoclast markers investigated in the study presented higher expression on the test implants than controls as follows: tartrate-resistant acid phosphatase (1.67-fold), calcitonin receptor (1.35-fold), and ATPase (1.25-fold). The test implants demonstrated higher expression of inflammatory markers interleukin-10 (1.53-fold) and tumour necrosis factor-α (1.61-fold) relative to controls. Conclusion. The protein-doped surface showed higher gene expression of typical genes involved in the osseointegration cascade than the control surface.
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| 13. |
- Westas, Emma, 1982, et al.
(författare)
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Bactericidal effect of photocatalytically-active nanostructured TiO2 surfaces on biofilms of the early oral colonizer, Streptococcus oralis
- 2017
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 105:8, s. 2321-2328
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the photocatalytic bactericidal effect of nanostructured anatase-rich titanium dioxide (TiO2) on microbial biofilms. Commercially pure titanium discs were spin-coated with photocatalytic TiO2 nanoparticles (P25). Uncoated discs were used as control (CTRL). Half of the CTRL and half of the P25-coated surfaces were coated with purified saliva (SAL) to give four different groups (CTRL, CTRL + SAL, P25 and P25 + SAL). Streptococcus oralis were allowed to form biofilms on the discs for 18 h and non-adherent cells were rinsed off. Bacterial viability was assessed at time 0 with Live/Dead BacLight staining and epifluorescence microscopy. The remaining discs were divided into a non-UV group and UVA-irradiated (1UV) group (irradiation time, 6 or 24 h). Thereafter, viability was assessed as above. Viability at time 0 was high and no dead cells were seen on any of the surfaces, even after 24 h, in the absence of UVA. However, after 24 h of exposure, the proportion of viable cells was reduced by 40% on the P25 discs compared to 0 and 6 h, and this effect was enhanced with a salivary pellicle. Members of mixed species biofilms differ in their susceptibility to the bactericidal effect of the surfaces tested and further investigations are needed to optimize the conditions.
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| 14. |
- Zambuzzi, Willian F., et al.
(författare)
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Nanometer Scale Titanium Surface Texturing Are Detected by Signaling Pathways Involving Transient FAK and Src Activations
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is known that physico/chemical alterations on biomaterial surfaces have the capability to modulate cellular behavior, affecting early tissue repair. Such surface modifications are aimed to improve early healing response and, clinically, offer the possibility to shorten the time from implant placement to functional loading. Since FAK and Src are intracellular proteins able to predict the quality of osteoblast adhesion, this study evaluated the osteoblast behavior in response to nanometer scale titanium surface texturing by monitoring FAK and Src phosphorylations. Methodology: Four engineered titanium surfaces were used for the study: machined (M), dual acid-etched (DAA), resorbable media microblasted and acid-etched (MBAA), and acid-etch microblasted (AAMB). Surfaces were characterized by scanning electron microscopy, interferometry, atomic force microscopy, x-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. Thereafter, those 4 samples were used to evaluate their cytotoxicity and interference on FAK and Src phosphorylations. Both Src and FAK were investigated by using specific antibody against specific phosphorylation sites. Principal Findings: The results showed that both FAK and Src activations were differently modulated as a function of titanium surfaces physico/chemical configuration and protein adsorption. Conclusions: It can be suggested that signaling pathways involving both FAK and Src could provide biomarkers to predict osteoblast adhesion onto different surfaces.
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