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| 2. |
- Echeverri Correa, Estefania, et al.
(author)
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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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In: Biomaterials Science. - : Royal Society of Medicine Press. - 2047-4830 .- 2047-4849. ; 11:9, s. 3144-3158
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Journal article (peer-reviewed)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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| 3. |
- Echeverri Correa, Estefania, et al.
(author)
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In vitro 3D model for monitoring glial cell responses to particles and ions released from spinal implants
- 2023
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Conference paper (peer-reviewed)abstract
- Spinal implants have been used for decades to treat different spinal conditions. However, certain implant-related complications have been attributed to the release of particles and ions due to corrosion and wear triggering local immune responses including the release of pro-inflammatory cytokines, leading to local inflammation. The impact of these particles and ions on cells from the central nervous system (CNS) remains largely unknown, with few studies examining the effects on glial cells1. Indeed, the particles may migrate to adjacent nervous tissues and increasing our knowledge of the glial cell response is essential since they play a crucial role in maintaining tissue homeostasis and protecting the CNS. Most prior studies have used traditional 2D culture models; however, these lack the 3D spatial arrangement of cells found in tissues where they form important interactions with the extracellular matrix. The aim of this study was to employ an open source bioprinter2 to extrude hydrogels containing glial cells into which experimental implant debris can be introduced, enabling monitoring of cell viability and inflammatory responses by fluorescence microscopy. We have previously established that mono-cultures of microglia and astrocytes can be 3D cultured in collagen hydrogels, and their viability monitored using the caspase-3/7 apoptosis reporter and propidium iodide labelling for cell death. Applying a bioprinting strategy to produce these glial-laden constructs increases the reproducibility of these models, and allows the study of a wide range of types and concentrations of particles, resulting in a valuable tool to increase the knowledge about the biological response generated by particles from spinal implants.
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| 5. |
- Engberg, Adam, et al.
(author)
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An open source extrusion bioprinter based on the E3D motion system and tool changer to enable FRESH and multimaterial bioprinting
- 2021
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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Bioprinting is increasingly used to create complex tissue constructs for an array of research applications, and there are also increasing efforts to print tissues for transplantation. Bioprinting may also prove valuable in the context of drug screening for personalized medicine for treatment of diseases such as cancer. However, the rapidly expanding bioprinting research field is currently limited by access to bioprinters. To increase the availability of bioprinting technologies we present here an open source extrusion bioprinter based on the E3D motion system and tool changer to enable high-resolution multimaterial bioprinting. As proof of concept, the bioprinter is used to create collagen constructs using freeform reversible embedding of suspended hydrogels (FRESH) methodology, as well as multimaterial constructs composed of distinct sections of laminin and collagen. Data is presented demonstrating that the bioprinted constructs support growth of cells either seeded onto printed constructs or included in the bioink prior to bioprinting. This open source bioprinter is easily adapted for different bioprinting applications, and additional tools can be incorporated to increase the capabilities of the system.
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| 6. |
- Fatsis-Kavalopoulos, Nikos, et al.
(author)
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CombiANT : Antibiotic interaction testing made easy
- 2020
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In: PLoS biology. - : PUBLIC LIBRARY SCIENCE. - 1544-9173 .- 1545-7885. ; 18:9
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Journal article (peer-reviewed)abstract
- Antibiotic combination therapies are important for the efficient treatment of many types of infections, including those caused by antibiotic-resistant pathogens. Combination treatment strategies are typically used under the assumption that synergies are conserved across species and strains, even though recent results show that the combined treatment effect is determined by specific drug-strain interactions that can vary extensively and unpredictably, both between and within bacterial species. To address this problem, we present a new method in which antibiotic synergy is rapidly quantified on a case-by-case basis, allowing for improved combination therapy. The novel CombiANT methodology consists of a 3D-printed agar plate insert that produces defined diffusion landscapes of 3 antibiotics, permitting synergy quantification between all 3 antibiotic pairs with a single test. Automated image analysis yields fractional inhibitory concentration indices (FICis) with high accuracy and precision. A technical validation with 3 major pathogens,Escherichia coli,Pseudomonas aeruginosa, andStaphylococcus aureus, showed equivalent performance to checkerboard methodology, with the advantage of strongly reduced assay complexity and costs for CombiANT. A synergy screening of 10 antibiotic combinations for 12E.coliurinary tract infection (UTI) clinical isolates illustrates the need for refined combination treatment strategies. For example, combinations of trimethoprim (TMP) + nitrofurantoin (NIT) and TMP + mecillinam (MEC) showed synergy, but only for certain individual isolates, whereas MEC + NIT combinations showed antagonistic interactions across all tested strains. These data suggest that the CombiANT methodology could allow personalized clinical synergy testing and large-scale screening. We anticipate that CombiANT will greatly facilitate clinical and basic research of antibiotic synergy.
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| 7. |
- Grzeszczak, Ana, 1995-, et al.
(author)
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Mechanical and Structural Evaluation of Synthetic Trabecular Bone Models Printed with Stereolithography
- 2021
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In: Mechanical and Structural Evaluation of Synthetic Trabecular Bone Models Printed with Stereolithography.
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Conference paper (peer-reviewed)abstract
- Mechanical and Structural Evaluation of Synthetic Trabecular Bone Models Printed with StereolithographyA. Grzeszczak1, S. Lewin1, O. Eriksson2, J. Kreuger2, C. Persson11Department of Materials Science and Engineering, Uppsala University, Uppsala, Sweden2Department of Medical Cell Biology, Uppsala University, Uppsala, SwedenINTRODUCTION: Synthetic bone models are needed to train surgeons but also to test and design medical equipment. However, currently available models do not accurately mimic the complex structure of trabecular bone [1]. This study aimed to investigate the suitability of stereolithography (SLA) printing to produce synthetic trabecular bone models.METHODS: The synthetic bone models were printed by SLA using a CAD-model generated from micro-computed tomography (micro-CT) synchrotron images of human trabecular bone [2]. To adjust the printing parameters, the influence of the following variables on the mechanical properties was investigated: printer type, orientation, resolution and UV-curing time. Subsequently, the trabecular CAD-model was printed at the original scale (scale factor 1), and with several enlarging factors. Mechanical properties were evaluated by compression and screw pullout tests, and structure replicability was assessed with micro-CT.RESULTS & DISCUSSION: The elastic modulus of the control group was not statistically different from that of the other batches after the printing parameters configuration, standard parameters were therefore used. The orientation of the samples on the build platform of the printer did not seem to have an influence on the ratio Bone Volume/Total Volume for trabecular samples. For the bone models with scaling factors below 1.8, micro-CT image analysis showed major artefacts due to printing and a low accuracy in trabecular thickness distribution. Analysis of the total printed volume showed a difference to the original model higher than 50% for scale 1.5 and lower than 10% for scales 1.8 and above (Fig. 1). A refined overlap comparison with the original bone model showed that the scale 1.8 exhibited errors higher than 20%, implying printing inaccuracies of the smaller details. The pullout strength obtained for SLA-printed parts was higher than for existing synthetic models (Sawbones™) and cadaveric specimens, but within the same range as FDM-printed parts in poly(lactic acid) [2].CONCLUSIONS: Trabecular bone models with a scale factor of 1.8 or greater could be produced with acceptable accuracy, but models with smaller scale factors were not well printed. Nevertheless, for the same 3D model, a higher resolution was reached by SLA as compared to FDM [2].ACKNOWLEDGEMENTS: The authors are grateful to Adam Engberg at U-PRINT: Uppsala University’s 3D-printing facility at the Disciplinary Domain of Medicine and Pharmacy for support and advice on the printers. This research was funded by Sweden’s Innovation Agency VINNOVA, grant number 2019-00029.REFERENCES: [1] M. Poukalova et al., “Pullout strength of suture anchors: Effect of mechanical properties of trabecular bone,” J. Biomech., vol. 43, no. 6, pp. 1138–1145, Apr. 2010, doi: 10.1016/j.jbiomech.2009.12.007. [2] D. Wu, A. Spanou, A. Diez-Escudero, and C. Persson, “3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling,” J. Mech. Behav. Biomed. Mater., vol. 103, p. 103608, Mar. 2020, doi: 10.1016/j.jmbbm.2019.103608.
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| 8. |
- Grzeszczak, Ana, 1995-, et al.
(author)
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Stereolithography shows potential in additive manufacturing ofsynthetic trabecular bone structures
- 2021
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In: Stereolithography shows potential in additive manufacturing ofsynthetic trabecular bone structures.
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Conference paper (other academic/artistic)abstract
- Title and AuthorsTitle: Stereolithography shows potential in additive manufacturing of synthetic trabecular bone structures.Authors: Ana Grzeszczak, Susanne Lewin, Olle Eriksson, Johan Kreuger, Cecilia Persson IntroductionSynthetic bone models are needed to train surgeons but also to test and design medical devices such as screws for fracture fixation. However, currently available models do not accurately mimic the trabecular bone and its complex structure [1]. This study aimed to investigate if stereolithography (SLA) additive manufacturing could produce synthetic trabecular bone models with high accuracy. Experimental methods The synthetic bone models were printed by SLA (Formlabs Black resin, Form3 printer). The CAD-model had been generated from micro-computed tomography (micro-CT) synchrotron images of human trabecular bone [2]. The model was printed at the original scale (scale factor 1), and with upscaling factors up to 4.3. Structure replicability was assessed with micro-CT, and the mechanical properties were evaluated by compression and screw pullout tests. Dense cylinders of the printed material were also tested in compression for material characterization.Results and discussionThe elastic moduli obtained by compression of dense cylinders were approximately ten times lower than average values for human cortical bone. For the trabecular bone models with scaling factors below 1.8, micro-CT image analysis showed major artefacts due to printing and a low accuracy in trabecular thickness distribution. Analysis of the total printed volume showed a difference to the original model higher than 50% for scale 1.5 (Fig. 1). However, this difference was less than 10% for scales 1.8 and above, although a refined overlap comparison with the original bone model showed that the scale 1.8 exhibited errors higher than 20%, implying printing inaccuracies of the smaller details. The pullout strength of SLA-printed parts was higher than for existing synthetic models (Sawbones™) and cadaveric specimens, but within the same range as FDM-printed parts in poly(lactic acid) [2].ConclusionIn conclusion, trabecular bone models with a scale factor of 1.8 or larger could be printed with acceptable accuracy, but models with smaller scale factors were not well represented. However, for the same 3D model, a higher resolution was achieved by SLA as compared to FDM [2]. AcknowledgementsThe authors are grateful to Adam Engberg at U-PRINT: Uppsala University’s 3D-printing facility at the Disciplinary Domain of Medicine and Pharmacy for support and advice on the printers. This research was funded by Sweden’s Innovation Agency VINNOVA, grant number 2019-00029.References[1] M. Poukalova et al., “Pullout strength of suture anchors: Effect of mechanical properties of trabecular bone,” J. Biomech., vol. 43, no. 6, pp. 1138–1145, Apr. 2010, doi: 10.1016/j.jbiomech.2009.12.007.[2] D. Wu, A. Spanou, A. Diez-Escudero, and C. Persson, “3D-printed PLA/HA composite structures as synthetic trabecular bone: A feasibility study using fused deposition modeling,” J. Mech. Behav. Biomed. Mater., vol. 103, p. 103608, Mar. 2020, doi: 10.1016/j.jmbbm.2019.103608.
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| 9. |
- Grzeszczak, Ana, et al.
(author)
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The Potential of Stereolithography for 3D Printing of Synthetic Trabecular Bone Structures
- 2021
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In: Materials. - : MDPI. - 1996-1944. ; 14:13
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Journal article (peer-reviewed)abstract
- Synthetic bone models are used to train surgeons as well as to test new medical devices. However, currently available models do not accurately mimic the complex structure of trabecular bone, which can provide erroneous results. This study aimed to investigate the suitability of stereolithography (SLA) to produce synthetic trabecular bone. Samples were printed based on synchrotron micro-computed tomography (micro-CT) images of human bone, with scaling factors from 1 to 4.3. Structure replicability was assessed with micro-CT, and mechanical properties were evaluated by compression and screw pull-out tests. The overall geometry was well-replicated at scale 1.8, with a volume difference to the original model of <10%. However, scaling factors below 1.8 gave major print artefacts, and a low accuracy in trabecular thickness distribution. A comparison of the model-print overlap showed printing inaccuracies of similar to 20% for the 1.8 scale, visible as a loss of smaller details. SLA-printed parts exhibited a higher pull-out strength compared to existing synthetic models (Sawbones (TM)), and a lower strength compared to cadaveric specimens and fused deposition modelling (FDM)-printed parts in poly (lactic acid). In conclusion, for the same 3D model, SLA enabled higher resolution and printing of smaller scales compared to results reported by FDM.
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| 10. |
- Kumar, Tharagan, 1990-
(author)
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The application of microfluidic devices and multifunctional fibers in cancer diagnostics
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Efficient separation and detection of rare cells in a mixed population is important in many biomedical applications. For instance, isolating and detecting circulating tumor cells (CTCs) from whole blood samples could allow for early cancer diagnosis and prognosis during treatment. CTCs are rare cells circulating in blood detached from the primary tumor site, carrying important information such as the origin of cancer and metastatic information. The detection of CTC from blood samples, besides being a minimally invasive procedure, could be vital in case of difficulty to access the tumor site via traditional biopsies, such as colon and pancreatic cancer. Microfluidics is a research field with great promise towards the development of methods to isolate and separate cells for clinical applications. Microfluidic based cell separation has been demonstrated using biological approaches using cell surface markers, and biophysical approaches using cell size, shape, and deformability. This thesis will focus on developing passive strategy using inertial microfluidics (biophysical, paper 1-4) and affinity biomarker (biochemical, paper 5) based strategy to isolate and analyze CTCs. Inertial microfluidics relies on inherent hydrodynamic forces, inertial forces, in flow through the microfluidic channel. Depending on the geometry of the channel, inertial forces drive the particles and cells to a specific streamline position, allowing for focusing and separation. In contrast, affinity-based isolation relies on biomarkers expressed on the surface of the targeted cells, which is highly specific. In paper 1, using the elasto inertial microfluidic technique, high throughput particle focusing and separation was achieved in a curved rectangular channel with a separation efficiency of 89% for 10 μm and 99% for the 15 μm particles at a high volumetric flow rate (1 mL/min). In paper 2, a detailed analysis of particle focusing was studied experimentally and numerically in a circular cross-section. Using the FENE-P model simulating non-Newtonian fluid and an immersed boundary method to account for the particles, it was observed that a combination of inertia and elasticity leads to several intermediate focusing positions. In paper 3, we developed a portable microflow cytometer using fiberoptics capillaries. By combining elasto inertial microfluidics and optical fibers, we focused particles and cells and demonstrated particle counting at a throughput of 2500 particles/second. In paper 4, we built an all-fiber separation and detection component and demonstrated a separation efficiency of 100% for the 10 μm and 97% for the 1 μm particles as a proof of principle. In addition, the separated 10 μm particles could beiiiquantified in the all-fiber component. In paper 5, an affinity-based separation approach was carried out to utilize the surface markers to capture and release viable CTCs for downstream analysis. A novel layer-by-layer nanofilm coating strategy was developed using cellulose nanofibril (CNF) built into multiple layers and functionalized with antibodies to capture the cells. After capture, the CNF were enzymatically degraded to release the CTCs. HCT116 colon cancer cells were captured with an efficiency of more than 97%, and when spiked in whole blood, an approximately 200 fold average enrichment was achieved compared to white blood cells. 80% of the cancer cells spiked in whole blood were recovered with 97% viability in less than 30 minutes.In summary, this thesis presents different microfluidics-based separation of cancer cells based on biophysical and biochemical properties. Using elasto inertial microfluidics, we developed several approaches to separate and detect cells and particles. Using layer-by-layer coating of CNF, we successfully demonstrated capture and release of cancer cells with maintained high viability. While the thesis has focused on different properties of cells for separation and analysis, combining these methods will be important for efficient isolation and characterization of CTCs for improved diagnostics.
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