| 1. |
- Aberg, Jonas, et al.
(författare)
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In vivo evaluation of an injectable premixed radiopaque calcium phosphate cement.
- 2011
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Ingår i: International journal of biomaterials. - : Hindawi Limited. - 1687-8795 .- 1687-8787. ; 2011
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Tidskriftsartikel (refereegranskat)abstract
- In this work a radiopaque premixed calcium phosphate cement (pCPC) has been developed and evaluated in vivo. Radiopacity was obtained by adding 0-40 % zirconia to the cement paste. The effects of zirconia on setting time, strength and radiopacity were evaluated. In the in vivo study a 2 by 3.5mm cylindrical defect in a rat vertebrae was filled with either the pCPC, PMMA or bone chips. Nano-SPECT CT analysis was used to monitor osteoblast activity during bone regeneration. The study showed that by adding zirconia to the cement the setting time becomes longer and the compressive strength is reduced. All materials evaluated in the in vivo study filled the bone defect and there was a strong osteoblast activity at the injury site. In spite of the osteoblast activity, PMMA blocked bone healing and the bone chips group showed minimal new bone formation. At 12 weeks the pCPC was partially resorbed and replaced by new bone with good bone ingrowth. The radiopaque pCPC may be considered to be used for minimal invasive treatment of vertebral fractures since it has good handling, radiopacity and allows healing of cancellous bone in parallel with the resorption of the cement.
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| 2. |
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| 3. |
- Echeverri Correa, Estefania, et al.
(författare)
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Decreasing the dissolution rate of silicon nitride coatings for spinal implants by the addition of Fe and C
- 2022
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Konferensbidrag (refereegranskat)abstract
- Spinal implants have been used for several decades to relieve pain and stabilise the spine, however an increase in the life span of implants is required due to younger and more active patients requiring spinal surgery. Silicon nitride-based coatings have been suggested as an alternative to metallic implants to reduce the release of detrimental ion and particles. However, due to the coating’s dissolution in the presence of water, reducing the dissolution rate by altering the coating composition is of high interest to ensure an adequate lifetime. The aim of this study was to investigate the dissolution rate of silicon nitride coatings containing Fe and C and the effect of the ions released on in vitro neural cell response. SiFeCN coatings were deposited by reactive sputtering using a combinatorial approach for efficient testing of different compositions. Compositional gradients were obtained for the investigated elements. SEM of the coated samples after exposure to cell media displayed stronger signs of dissolution on the SiN reference than the alloyed coatings. The addition of Fe and C decreased the ion release of the coating itself compared to the SiN coating. Indirect biocompatibility tests suggested that microglial cell viability was comparable to that of CoCrMo reference samples and SiN coatings. In conclusion, the results indicate the possibility of decreasing the dissolution rate of SiN coatings by the addition of Fe and C, while maintaining the biocompatibility as confirmed by the cytotoxicity tests on neural cells. Therefore, SiFeCN coatings merit further investigation for use in spinal implants. This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 812765 and from the European Union’s Seventh Framework Programme (FP7/2007-2013), grant agreement GA-310477(LifeLongJoints).
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| 4. |
- Echeverri Correa, Estefania, et al.
(författare)
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Dissolution and biocompatibility of combinatorially sputtered SiCrNbN coatings
- 2021
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Konferensbidrag (refereegranskat)abstract
- Hip and knee joint replacements have been some of the most successful surgeries for the treatment of patients with chronic pain due to arthritis. A current challenge is however the younger and more active patients, which demands longer-lasting devices that will withstand several decades of cyclic loading. Corrosion and wear products are herein a concern since they can cause localized inflammation leading to periprosthetic bone loss and potentially implant loosening, necessitating revision surgery. One approach to overcome the long-term issues is to develop materials more resistant to wear and corrosion, as well as materials giving less of an inflammatory response, e.g. by depositing a ceramic coating which acts as a barrier to the release of metal ions from the substrate as well as improving the wear resistance. Silicon nitride is a promising candidate because of its low wear rates and the possibility to limit the adverse effects of wear debris due to its slow dissolution in aqueous solutions.Purpose of the studyThis study aimed to investigate the dissolution and biocompatibility of SiCrNbN coatings deposited on cobalt chromium (CoCr) substrates. We hypothesized that the ceramic coating will reduce metal ion release compared to uncoated CoCr without affecting its biocompatibility.MethodsThe SiCrNbN coatings were deposited on CoCr disc substrates by reactive sputtering in an in-house built equipment, allowing for combinatorial processes, using Si, Cr and Nb solid targets. Nitrogen was supplied as a reactive gas. To improve the adhesion of the coating a CrN interlayer was deposited. The coatings were characterized in 9 points using x-ray photoelectron spectroscopy (XPS), vertical scanning interferometry (VSI) and scanning electron microscopy (SEM). The points were placed in a 3x3 grid with 22.5 mm between each point. The dissolution was evaluated by exposing the coated samples to cell media for 7 days. The obtained extracts were diluted (neat extracts (1:1), and 3 two-fold dilutions (1:2, 1:4 and 1:8)) and used to measure ion levels with inductively coupled plasma (ICP-OES) and to assess indirect biocompatibility in vitro using the tetrazolium dye MTT and L929 fibroblast cells. ResultsThe XPS results revealed compositional gradients with Si ranging between 27.4-32.8 at.%, Cr 4.1-10.9 at.%, Nb 3.5-8.4 at.%, N 41.8-46.8 at.% and O 10.9-14.6 at.%. SEM revealed coating thicknesses between 320-590 nm, and interlayers approx. 50 nm thick. Images displayed an overall smooth surface with an average roughness, Ra, of 5.6 to 9.3 nm, similar for all points. Grooves from polishing and occasional features at the microscale were observed, likely formed during deposition. The ICP results showed a reduction in Co ions from the substrate in the coated samples compared to uncoated. The cell viability results suggest that fibroblasts tolerated the neat extracts and their dilutions (1:1, 1:2, 1:4) obtained from the coated samples in a dose-dependent manner. ConclusionsThe findings from this study suggest that the differences in composition did not affect the surface properties. The material characteristics indicate that silicon nitride has a promising potential to be used as a coating in metallic implants to improve corrosion resistance and reduce ion release, warranting further biological evaluation.
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| 5. |
- Echeverri Correa, Estefania, et al.
(författare)
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Dissolution Behaviour and Biocompatibility of Combinatorially Sputtered SiFeCN Coatings for Spinal Implants
- 2022
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Konferensbidrag (refereegranskat)abstract
- INTRODUCTION One of the main limiting factors to the life span of spinal implants is the release of detrimental ions and particles, which are typically produced by wear and corrosion1,2. One suggested approach to overcome these issues is the use of silicon nitride-based coatings on metallic implants because of their low wear rates and their ability to slowly dissolve in aqueous solutions into biocompatible ions only, which could be advantageous in terms of limiting the effects of wear debris and ion release3. A previous study found that alloying the silicon nitride coating with Fe and C did not have a negative effect on mechanical properties nor biocompatibility in a direct contact in vitro test4. However, the dissolution behaviour of the coatings remains to be investigated. Furthermore, due to the close proximity to nerve tissues in spinal implants, the effect of the ions released on the neural tissue is a concern. The present study aimed to study the dissolution behaviour and in vitro neural cell response of SiFeCN coatings. A combinatorial approach was used for efficient screening of different compositions. EXPERIMENTAL METHODS SiFeCN coatings were deposited on CoCr disc substrates by reactive sputtering in an in-house built equipment, allowing for combinatorial processes, using Si, Fe and C solid targets. Nitrogen was supplied as a reactive gas. The coatings were characterized in 9 points using x-ray photoelectron spectroscopy (XPS), vertical scanning interferometry (VSI) and scanning electron microscopy (SEM). The points were placed in a 3x3 grid with 22.5 mm between each point. The dissolution behaviour was evaluated by exposing the coated samples to cell media for 14 days. The obtained extracts were diluted (1:32, 1:48, 1:64 and 1:80 dilution) and used to measure ion levels with inductively coupled plasma (ICP-OES) and to assess indirect biocompatibility in vitro using the MTT assay and glial cells. RESULTS AND DISCUSSION The XPS results showed compositional gradients of Si ranging between 36.4-47.3 at.%, Fe 1.4-9.3 at.% and C 4.5-13.9 at.% with average surface roughness, Sa, of 7.4 to 11.1 nm, similar to SiN and CoCr reference materials. SEM after exposure displayed signs of dissolution with visibly increased porosity for the coated samples. The SiN reference also showed substantial changes to the surface. The ICP results (Figure 1) showed a reduction in Co ions from the substrate in the coated samples compared to uncoated. Moreover, the addition of Fe and C decreased the ion release from the coating compared to the SiN reference coating. Extract biocompatibility tests suggested that glial cells tolerated the extracts and their dilutions obtained from the coated samples in a dose- dependent manner and the cell viability was comparable to that of the uncoated CoCr and SiN coating. CONCLUSIONS The findings from this study suggest that using iron and carbon as alloying elements in silicon nitride coatings has the potential to reduce ion release from a metallic substrate and lower the dissolution rate of the coating, while having a comparable cell response to that of the CoCr and SiN control materials. Therefore, SiFeCN coatings merit further investigation as a future option for spinal implants. REFERENCES 1.Shimamura Y. et al., Spine. 33(4):351–355, 2008 2.Vicars R. et al., Comprehensive Biomaterials II. (pp. 246–264), 20173. Pettersson M. et al., ACS Biomaterials Science and Engineering. 2(6):998–1004, 20164. Skjöldebrand C. et al., Materials (Basel). 13(9):1–16, 2020 ACKNOWLEDGMENTS This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 812765 and from the European Union’s Seventh Framework Programme (FP7/2007-2013), grant agreement GA-310477(LifeLongJoints).
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| 6. |
- Echeverri Correa, Estefania, et al.
(författare)
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Fe and C additions decrease the dissolution rate of silicon nitride coatings and are compatible with microglial viability in 3D collagen hydrogels
- 2023
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Ingår i: Biomaterials Science. - : Royal Society of Medicine Press. - 2047-4830 .- 2047-4849. ; 11:9, s. 3144-3158
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Tidskriftsartikel (refereegranskat)abstract
- Silicon nitride (SiN) coatings may reduce unwanted release of metal ions from metallic implants. However, as SiN slowly dissolves in aqueous solutions, additives that reduce this dissolution rate would likely increase the lifetime and functionality of implants. Adding iron (Fe) and carbon (C) permits tuning of the SiN coatings’ mechanical properties, but their effect on SiN dissolution rates, and their capacity to reduce metal ion release from metallic implant substrates, have yet to be investigated. Such coatings have recently been proposed for use in spinal implants; therefore, it is relevant to assess their impact on the viability of cells expected at the implant site, such as microglia, the resident macrophages of the central nervous system (CNS). To study the effects of Fe and C on the dissolution rate of SiN coatings, compositional gradients of Si, Fe and C in combination with N were generated by physical vapor deposition onto CoCrMo discs. Differences in composition did not affect the surface roughness or the release of Si, Fe or Co ions (the latter from the CoCrMo substrate). Adding Fe and C reduced ion release compared to a SiN reference coating, which was attributed to altered reactivity due to an increase in the fraction of stabilizing Si–C or Fe–C bonds. Extracts from the SiN coatings containing Fe and C were compatible with microglial viability in 2D cultures and 3D collagen hydrogels, to a similar degree as CoCrMo and SiN coated CoCrMo reference extracts. As Fe and C reduced the dissolution rate of SiN-coatings and did not compromise microglial viability, the capacity of these additives to extend the lifetime and functionality of SiN-coated metallic implants warrants further investigation.
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| 7. |
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| 8. |
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| 9. |
- Echeverri Correa, Estefania, et al.
(författare)
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Reducing the dissolution rate of silicon nitride coatings for spinal implants using Fe and C as alloying elements
- 2023
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Konferensbidrag (refereegranskat)abstract
- INTRODUCTION: Wear and corrosion may lead to a release of particles and ions from spinal implants, which is a concern because of their potentially detrimental effect on the life span of the implant [1]. Silicon nitride-based coatings have been suggested as an option to reduce the release of metal ions from an implant. In addition, any particles produced will slowly dissolve, releasing only biocompatible ions [2]. It is of high interest to reduce the dissolution rate of the coating to ensure an adequate lifetime [3]. The present study aimed to assess the effect of Fe and C additions to silicon nitride coatings in terms of dissolution rate as well as the impact of the released ions on the in vitro neural cell response.METHODS: Using a combinatorial approach, SiFeCN coatings were deposited on CoCr disc substrates by reactive sputtering in an in-house built equipment. The coatings were characterized in 9 points using x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The dissolution behaviour was evaluated by exposing the coated samples to cell media for 14 days. The obtained extracts were used to measure ion release with inductively coupled plasma - optical emission spectrometry (ICP-OES) and to assess cell viability of microglia (C8-B4 cell line) using the MTT assay. RESULTS: The XPS results showed compositional gradients of Si ranging from 35.0 to 47.3 at.%, Fe from 1.4 to 9.3 at.% and C from 4.5 to 13.9 at.%. SEM of focused ion beam (FIB) cross-sections revealed coating thicknesses between 427-534 nm. SEM of the coating after exposure showed substantial signs of dissolution with visibly increased porosity for the SiN coating, while the SiFeCN coatings appeared less affected. SiFeCN coatings appeared more affected by dissolution for increasing Si contents. The estimated dissolution rate of the SiN coating was 8.3 nm/day, while the rate of SiFeCN coatings was 5.2-6.8 nm/day. The ICP results showed a reduction in Co ions from the substrate in the coated samples compared to uncoated CoCr. Moreover, the levels of detected Si ions were lower for the SiFeCN compared to SiN reference. Indirect biocompatibility tests suggested that microglia cell viability was comparable for the SiFeCN coatings, the uncoated CoCr and the SiN coating.DISCUSSION & CONCLUSIONS: The compositional gradients influenced the thickness of the coating, giving a slight thickness increase in the coatings with the increment of Si content. In addition, the ICP results showed the capability of the coating to act as a barrier to the release of ions from the substrate. Furthermore, the presence of Fe and C in the coating causes a decrease in the ion release from the coating, indicative of a lower dissolution rate, which was supported by the thickness measurements. The findings from this study indicate that using Fe and C as alloying elements can lower the dissolution rate of the silicon nitride-based coating while showing positive indications of biocompatibility on neural cells. Therefore, SiFeCN coatings merit further investigation as a future option for spinal implants.REFERENCES: 1Y. Shimamura et al (2008) Spine. 33:351–355. 2M. Pettersson et al (2016) ACS Biomater. Sci. Eng. 2:998–1004. 3C. Skjöldebrand et al (2022) Biomater Sci, 10:3757–3769.ACKNOWLEDGEMENTS: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 812765 and from the European Union’s Seventh Framework Programme (FP7/2007-2013), grant agreement GA-310477(LifeLongJoints).
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| 10. |
- Geissel, Felix J., et al.
(författare)
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Nanostructured Ag-Bioglass Implant Coatings with Antibacterial and Osteogenic Activity
- 2023
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Ingår i: Advanced Materials Interfaces. - : Wiley-VCH Verlagsgesellschaft. - 2196-7350. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Bone implant failure due to aseptic loosening and biofilm infections is an increasing healthcare problem. Implants may be coated with nanoparticles to avoid bacterial colonization and promote osseointegration. However, these nanocoatings often require long, expensive, and complex manufacturing routes with limited clinical translation potential. Here, a multifunctional nanoparticle coating consisting of silver (Ag) and bioglass (BG) is investigated to overcome current limitations by providing synchronously antibacterial and osteogenic effect. Flame spray pyrolysis (FSP) is exploited as a scalable and reproducible process to synthesize large quantities of nanoparticles and deposit them on titanium (Ti) substrates. The deposited nanocoatings show a homogeneous morphology and biomineralize after soaking in simulated body fluid (SBF), while their adhesion on Ti substrates is promoted by in situ flame annealing. The Ag+ ion release from Ag containing BG samples inhibits Staphylococcus aureus biofilm formation up to 3 log units, while the osteogenic responses of pre-osteoblastic cells directly grown on AgBG samples show similar levels of alkaline phosphatase activity, calcium and collagen production when compared to pure Ti. The inexpensively synthesized multifunctional AgBG nanostructured implant coatings exert a high bioactivity and antibacterial response while maintaining high biocompatibility. The insights of this study can direct the development of multifunctional implant coatings.
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