| 1. |
- Hulander, Mats, et al.
(författare)
-
Gradients in surface nanotopography used to study platelet adhesion and activation
- 2013
-
Ingår i: Colloids and Surfaces B-Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 110, s. 261-269
-
Tidskriftsartikel (refereegranskat)abstract
- Gradients in surface nanotopography were prepared by adsorbing gold nanoparticles on smooth gold substrates using diffusion technique. Following a sintering procedure the particle binding chemistry was removed, and integration of the particles into the underlying gold substrate was achieved, leaving a nanostructured surface with uniform surface chemistry. After pre-adsorption of human fibrinogen, the effect of surface nanotopography on platelets was studied. The use of a gradient in nanotopography allowed for platelet adhesion and activation to be studied as a function of nanoparticle coverage on one single substrate. A peak in platelet adhesion was found at 23% nanoparticle surface coverage. The highest number of activated platelets was found on the smooth control part of the surface, and did not coincide with the number of adhered platelets. Activation correlated inversely with particle coverage, hence the lowest fraction of activated platelets was found at high particle coverage. Hydrophobization of the gradient surface lowered the total number of adhering cells, but not the ratio of activated cells. Little or no effect was seen on gradients with 36 nm particles, suggesting the existence of a lower limit for sensing of surface nano-roughness in platelets. These results demonstrate that parameters such as ratio between size and inter-particle distance can be more relevant for cell response than wettability on nanostructured surfaces. The minor effect of hydrophobicity, the generally reduced activation on nanostructured surfaces and the presence of a cut-off in activation of human platelets as a function of nanoparticle size could have implications for the design of future blood-contacting biomaterials.
|
|
| 2. |
- Shah, Furqan A., et al.
(författare)
-
3D printed Ti6Al4V implant surface promotes bone maturation and retains a higher density of less aged osteocytes at the bone-implant interface.
- 2016
-
Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 30, s. 357-367
-
Tidskriftsartikel (refereegranskat)abstract
- For load-bearing orthopaedic applications, metal implants having an interconnected pore structure exhibit the potential to facilitate bone ingrowth and the possibility for reducing the stiffness mismatch between the implant and bone, thus eliminating stress-shielding effects. 3D printed solid and macro-porous Ti6Al4V implants were evaluated after six-months healing in adult sheep femora. The ultrastructural composition of the bone-implant interface was investigated using Raman spectroscopy and electron microscopy, in a correlative manner. The mineral crystallinity and the mineral-to-matrix ratios of the interfacial tissue and the native bone were found to be similar. However, lower Ca/P ratios, lower carbonate content, but higher proline, phenylalanine and tyrosine levels indicated that the interfacial tissue remained less mature. Bone healing was more advanced at the porous implant surface (vs. the solid implant surface) based on the interfacial tissue ν1 CO3(2-)/ν2 PO4(3-) ratio, phenylalanine and tyrosine levels approaching those of the native bone. The mechanosensing infrastructure in bone, the osteocyte lacuno-canalicular network, retained ∼40% more canaliculi per osteocyte lacuna, i.e., a 'less aged' morphology at the interface. The osteocyte density per mineralised surface area was ∼36-71% higher at the interface after extended healing periods.
|
|
| 3. |
- Shah, Furqan A., et al.
(författare)
-
Long-term osseointegration of 3D printed CoCr constructs with an interconnected open-pore architecture prepared by electron beam melting.
- 2016
-
Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 36:May, s. 296-309
-
Tidskriftsartikel (refereegranskat)abstract
- In orthopaedic surgery, cobalt chromium (CoCr) based alloys are used extensively for their high strength and wear properties, but with concerns over stress shielding and bone resorption due to the high stiffness of CoCr. The structural stiffness, principally related to the bulk and the elastic modulus of the material, may be lowered by appropriate design modifications, to reduce the stiffness mismatch between metal/alloy implants and the adjacent bone. Here, 3D printed CoCr and Ti6Al4V implants of similar macro-geometry and interconnected open-pore architecture prepared by electron beam melting (EBM) were evaluated following 26week implantation in adult sheep femora. Despite higher total bone-implant contact for Ti6Al4V (39±4%) than CoCr (27±4%), bone formation patterns were similar, e.g., densification around the implant, and gradual ingrowth into the porous network, with more bone in the outer half (periphery) than the inner half (centre). Raman spectroscopy revealed no major differences in mineral crystallinity, the apatite-to-collagen ratio, or the carbonate-to-phosphate ratio. Energy dispersive X-ray spectroscopy showed similar Ca/P ratio of the interfacial tissue adjacent to both materials. Osteocytes made direct contact with CoCr and Ti6Al4V. While osteocyte density and distribution in the new-formed bone were largely similar for the two alloys, higher osteocyte density was observed at the periphery of the porous network for CoCr, attributable to slower remodelling and a different biomechanical environment. The results demonstrate the possibility to achieve bone ingrowth into open-pore CoCr constructs, and attest to the potential for fabricating customised osseointegrated CoCr implants for load-bearing applications.
|
|
| 4. |
|
|
| 5. |
- Thorfve, Anna, 1982, et al.
(författare)
-
Hydroxyapatite coating affects the Wnt signaling pathway during peri-implant healing in vivo
- 2014
-
Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1742-7061 .- 1878-7568. ; 10:3, s. 1451-1462
-
Tidskriftsartikel (refereegranskat)abstract
- Owing to its bio- and osteoconductivity, hydroxyapatite (HA) is a widely used implant material, but its osteogenic properties are only partly evaluated in vitro and in vivo. The present study focused on bone healing adjacent to HA-coated titanium (Ti) implants, with or without incorporated lithium ions (Li+). Special attention was given to the Wnt signaling pathway. The implants were inserted into rat tibia for 7 or 28days and analyzed ex vivo, mainly by histomorphometry and quantitative real-time polymerase chain reaction. HA-coated implants showed, irrespective of Li+ content, bone-implant contact (BIC) and removal torque significantly higher than those of reference Ti. Further, the expressions of OCN, CTSK, COL1A1, LRP5/6 and WISP1 were significantly higher in implant-adherent cells of HA-coated implants, with or without Li+. Significantly higher β-catenin expression and significantly lower COL2A1 expression were observed in peri-implant bone cells from HA with 14ngcm-2 released Li+. Interestingly, Ti implants showed a significantly larger bone area in the threads than HA with 39ngcm-2 released Li+, but had a lower BIC than any HA-coated implant. This study shows that HA, with or without Li+ is a strong activator of the Wnt signaling pathway, and may to some degree explain its high bone induction capacity.
|
|
| 6. |
- Åberg, Jonas, 1982-, et al.
(författare)
-
Biocompatibility and resorption of a radiopaque premixed calcium phosphate cement
- 2012
-
Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 100A:5, s. 1269-1278
-
Tidskriftsartikel (refereegranskat)abstract
- Calcium phosphate cements (CPC) are used as bone void filler in various orthopedic indications; however, there are some major drawbacks regarding mixing, transfer, and injection of traditional CPC. By using glycerol as mixing liquid, a premixed calcium phosphate cement (pCPC), some of these difficulties can be overcome. In the treatment of vertebral fractures the handling characteristics need to be excellent including a high radio-opacity for optimal control during injection. The aim of this study is to evaluate a radiopaque pCPC regarding its resorption behavior and biocompatibility in vivo. pCPC and a water-based CPC were injected into a circle divide 4-mm drilled femur defect in rabbits. The rabbits were sacrificed after 2 and 12 weeks. Cross sections of the defects were evaluated using histology, electron microscopy, and immunohistochemical analysis. Signs of inflammation were evaluated both locally and systemically. The results showed a higher bone formation in the pCPC compared to the water-based CPC after 2 weeks by expression of RUNX-2. After 12 weeks most of the cement had been resorbed in both groups. Both materials were considered to have a high biocompatibility since no marked immunological response was induced and extensive bone ingrowth was observed. The conclusion from the study was that pCPC with ZrO2 radiopacifier is a promising alternative regarding bone replacement material and may be suggested for treatment of, for example, vertebral fractures based on its high biocompatibility, fast bone ingrowth, and good handling properties.
|
|
| 7. |
- Åberg, Jonas, 1982-, et al.
(författare)
-
In vitro and in vivo evaluation of an injectable premixed calcium phosphate cement : cell viability and immunological response from rat
- 2010
-
Ingår i: International Journal of Nano and Biomaterials. - 1752-8941. ; 3:3, s. 203-221
-
Tidskriftsartikel (refereegranskat)abstract
- By using premixed calcium phosphate cement (CPC) the handling properties of the cement are drastically improved, which is a challenge for traditional injectable CPC. In this article, a premixed acidic CPC has been compared to a conventional water mixed brushite cement to evaluate whether the premixed concept affects the biological response. The cements were evaluated regarding the pH-variation in simulated body fluid (SBF). Further, the biocompatibility of the cement with human mesenchymal stem cells (MSC) was studied in vitro and eventual inflammation properties studied in vivo, after subcutaneous material injections in rats. A larger pH decrease was seen for the conventional cement than the premixed cement in SBF. For both materials, > 90% of the MSC remained alive in vitro. No systemic or macroscopic inflammation was detected, only a mild microscopic inflammation was detected around both materials. In addition to the handling benefit of premixed cements compared to conventional water mixed CPC, the premixed CPC in the present study demonstrated high and in comparison to conventional CPC comparable biocompability, both in vitro and in vivo.
|
|
| 8. |
- Akman, Adnan, et al.
(författare)
-
Effect of minor gallium addition on corrosion, passivity, and antibacterial behaviour of novel β-type Ti–Nb alloys
- 2023
-
Ingår i: Journal of Materials Research and Technology. - 2238-7854. ; 25, s. 4110-4124
-
Tidskriftsartikel (refereegranskat)abstract
- Metastable Ti–Nb alloys are promising bone-implant materials due to improved mechanical biofunctionality and biocompatibility. To overcome increasing bacterial infection risk, alloying with antibacterial elements is a promising strategy. This study investigates the effect of minor gallium (Ga) additions (4, 8 wt% Ga) to as-cast and solution-treated β-type Ti–45Nb-based alloy (96(Ti–45Nb)-4Ga, 92(Ti–45Nb)-8Ga (wt.%)) on corrosion and passive film properties, as well as cytocompatibility and antibacterial activity. The electrochemical properties were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analyses in phosphate-buffered saline (PBS). X-ray photoelectron spectroscopy (XPS) was performed to analyze the chemical composition of passive films. Early adhesion and viability of macrophages and Staphylococcus aureus were assessed by nucleocounting and colony-forming unit counting, respectively. The results showed that high corrosion resistance and passive film properties of Ti–45Nb are retained and even slightly improved with Ga. EIS results revealed that Ga addition improves the passive film resistance. XPS measurements of 92(Ti–45Nb)-8Ga show that the passive film contains Ti-, Nb- and Ga-based oxides, implying the formation of mixed (Ti–Nb-Ga) oxides. In addition, marginal Ga ion release rate was detected under free corrosion conditions. Therefore, it can be assumed that Ga species may contribute to passive film formation on Ga-containing alloys. The 92(Ti–45Nb)-8Ga elicited an antibacterial effect against S. aureus compared to cp-Ti at 4 h. Moreover, Ga-containing alloys showed good cytocompatibility with THP-1 macrophages at 24 h. In conclusion, it was demonstrated that Ga additions to Ti–45Nb are beneficial to corrosion resistance and showed promising initial host and bacterial interactions.
|
|
| 9. |
|
|
| 10. |
- Ballo, Ahmed, 1978, et al.
(författare)
-
Bone response to physical-vapour-deposited titanium dioxide coatings on titanium implants
- 2013
-
Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 24:9, s. 1009-1017
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to investigate the correlation between coating thickness and the crystal structure of physical-vapour-deposited (PVD) titanium dioxide coatings, and to evaluate their in vivo biocompatibility. Materials and methods: The PVD TiO 2 coatings of different thickness were deposited on machined titanium grade 2 screw-shaped implants. Non-coated titanium implants were used as controls. Coating properties such as thickness, crystal structure, coating morphology and roughness were characterized. Forty-eight implants were placed randomly into both tibias of 16 rats. The animals were euthanized 7 and 28 days postsurgery and block biopsies were prepared for histology, histomorphometry and SEM analysis. Results: The thicknesses of the PVDTiO 2 coatings were 120 and 1430 nm respectively. Histologically, new bone formed on all implant surfaces. The mean percentage of newly formed bone in contact with the implant (BIC) was significantly higher at early healing time (7 days) for the 120 nm thick PVD coating (39 ± 14%) than for both the 1430 nm thick PVD coating (22 ± 10%) (P = 0.043) and the machined surface (22 ± 9%) (P = 0.028). This difference was no longer evident after 28 days (P = 0.867). Conclusion: Bone formation and bone-to-implant contact are achieved to the same degree for TiO 2 surface modifications prepared by a PVD process as clinically used, machined titanium. Furthermore, a relatively thinner PVD coating promotes a higher degree of bone apposition shortly after implantation, thereby providing rationales for exploring the potential clinical use of these modifications.
|
|
