2,181 research outputs found
Development of functionally graded constructs via 3D microfluidic bioprinting for the regeneration of skeletal defects
No full textSkeletal tissue engineering aims to prevail limitations of traditional treatments for bone defects by developing biomaterials that mimic the complex hierarchical architecture of natural bone. However, current biofabrication techniques face challenges in achieving both structural precision and biological compatibility. A major limitation is the lack of scalable methods to produce functionally graded materials (FGM) that support cell proliferation and differentiation while maintaining mechanical stability. This thesis proposes the development of a 3D microfluidic bioprinting platform using oil-in-water (O/W) and water-in-water emulsions (W/W) to fabricate porous scaffolds with controlled gradient structures. Crucially, integrating low-intensity pulsed ultrasound (LIPUS) stimulation and microbubbles (MBs) into the 3D bioprinting process for the first time, a functional response for cell growth and enhanced the osteogenic differentiation of skeletal stem cells (SSCs) was elicited. The results demonstrate that the 3D bioprinted constructs can actively promote effective bone tissue regeneration, addressing key limitations of current regenerative strategies, aforementioned. This thesis provides a novel, scalable solution for the creation of biocompatible and functional skeletal tissue constructs, with significant implications for clinical applications in bone repair
Microfluidic 3D biofabrication for the patterning of hierarchical gradient constructs
No full textINTRODUCTION: Functionally graded materials (FGMs) are ubiquitous in human tissues. Nevertheless, there has been limited attempt in replicating FGMs in 3D to generate constructs for tissue engineering and regenerative medicine purposes [1,2]. Here, we describe the fabrication of FGMs harnessing oil-in-water (o-w) and water-in-water (w-w) emulsions using a microfluidic flow- focusing printhead and a fluid-gel support bath, to engineer hierarchically functional implants. METHODS: An organic (cyclohexane) or biocompatible dispersed phase was fractioned in a continuous (Dextran, gelatin, hyaluronic acid methacryloyl (DexMA, GelMA, HAMA)) phase in a flow- focusing microfluidic printhead. Physico-chemical analysis was carried out using scanning electron microscopy (SEM), optical coherence tomography (OCT) and dynamic mechanical analysis (DMA). 3D deposition of FGMs was carried out in an agarose fluid-gel previously described [3]. Human bone marrow stromal (HBMSCs), vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) were encapsulated either in the dispersed or the continuous phase of the w-w emulsion, printed and implanted in a chick chorioallantoic membrane (CAM) model.
RESULTS: Deposited o-w and w-w fibres were tailored in porous content depending on the ratio of dispersed and continuous phase flows. On-chip characterisation revealed a significant proportionality (p<0.0001) between the diameter of the droplets and the volume fraction of the dispersed phase. Physico-chemical characterisation (SEM, OCT, DMA) of the printed scaffolds revealed hierarchically distributed porosity and preserved architecture following 3D deposition. DexMA, GelMA, HAMA were independently 3D printed comprising a variable set of porous density gradient. HBMSCs were printed when included either in the dispersed or the continuous phase, revealing no significant difference in viability post-printing. VEGF and BMP-2 included in the dispersed phase and patterned in 3D, elicited a tuneable release according to the size and density of the encapsulating droplets. HBMSCs were found functional upon stimulation with VEGF or BMP-2 following implantation in CAM, demonstrating the ability to produce readily implantable skeletal constructs.
DISCUSSION & CONCLUSIONS: FGM precursors (o-w, w-w) did not influenced the dispersion formation characteristics and reproducibility, offering a rapid and functional platform for the fabrication of hierarchical constructs. Altogether, we highlighted the synergistic combination of microfluidic technology with a bioprinting platform for the patterning of FGMs, demonstrating the engineering of a biphasic system particularly relevant for the control of densities during the biofabrication of tissue substitutes and implants
Harnessing microfluidic bioprinting to fabricate gradient-like porous 3D constructs via emulsion ink deposition
No full textThe exceptional properties of natural structures with density gradients (e.g. bone, sponges,bamboo) have stimulated the interest in reproducing such complex architectures harnessingbiopolymer functionality. However, the possibility to generate a hierarchical structurecomprising multiple density gradient has not yet demonstrated, mainly due to the lack oftechnological advancements in engineering of new emulsion materials and rapid fabricationplatforms.In the current work, we reported the 3D printing of porosity-controlled dextran methacrylate(DexMA) oil-in-water (o-w) emulsions using a microfluidic circuit and a fluid-gel supportbath. The fabrication of density gradient scaffolds within a supporting gel overcomes theproblems associated with low-viscosity bioink extrusion in 3D printing, supporting densitygradient structures that would be otherwise impossible to print in-air. The density gradientwas engineered using a flow-focusing printhead. The characterisation of the emulsionsdemonstrated how the regulation of the continuous and dispersed phases by using microfluidicpumps allowed the controlled and automated tuning of the material final porosity. Therefore,we proved that a higher droplet diameter is obtained by increasing the flow rate of the oil phasewith a direct and significant proportionality between the diameter and the volume fraction ofthe dispersed phase (p<0.0001). The rheological characterisation of the emulsions revealeda decrease in viscosity as the applied shear rate increased. The continuous phase of DexMAand Pluronic F-68 exhibited a Newtonian fluid-like trend, while the emulsions presented anincreasingly pseudoplastic behaviour with expanding dispersed phase volume fraction.To show the effectiveness of the developed methodology, we realised complex geometriesconsisting of porous biopolymer fibres, as well as porous scaffolds with axial (two, four andalternate) and radial density obtain differential regions within a single construct. The inclusion ofphoto-radical initiators in the outer phase of the inks enabled the crosslinking of the structure,following printing, directly into the supporting fluid-gel medium.The 3D printed porous scaffolds exhibited high-end mechanical properties and elastic responseto applied strains. Furthermore, morphological characterisation allowed the observation ofthe hierarchical internal porous architecture of the scaffolds using X-ray computed micro-tomography (μCT), scanning electron (SEM) and laser scanning confocal microscopy (LSCM),confirming the ability of the novel bioprinting platform to deposit high-resolution densitygradient constructs in 3D.Moreover, we demonstrated the possibility to print highly complex density gradient structures (e.g. free-standing stairs, inverted pyramids, hollow structures) with extremely low viscosityusing an agarose fluid-gel. Furthermore, we investigated the printing of a combination ofmaterials (DexMA and GelMA; DexMA and nHA) by a multi-inlet flow-focusing printhead,resulting in density gradient structures with hierarchical mechanical properties and swellingability.Altogether, this work outlines the potential of combining microfluidics and rapid prototypingtechniques with the use of a suspending medium, providing a viable alternative for optimally 3Dprinting of biphasic systems with low viscosities and controlled densities
Martina Drijverová and her literary works for children (author´s portrait)
No full textThis thesis Martina Drijverova and her literatur for children (the author´s portrait) is engaged in work of writer and screenwriter Martina Drijeverová. She is an excellent writer of literature for children. In the first part of this work her story writing is mentioned and the second part deals with her fairy-tale writing. The other author´s work written for children is in the third part. The conclusion of this thesis appreciates the author´s credit in literature for chidlren. Analysis of some books are available. The supplementary part is composed of autor´s biography and her photograph, some book covers, list of the autor´s work {--} televiews, radio plays and serials, audio tapes and CDs, stage plays, books written in Braille
HERStory Makers 2022: Martina Čagalj
No full textMartina Čagalj is a PhD candidate at the University of Split studying seaweeds as a potential source of bioactive compounds. She took part in HERStory Makers 2022.What is HERStory Makers?HERStory Makers is a social media competition for female-identifying early career researchers to share their research, their career journeys, and to inspire the next generation. Winners are selected by public vote. HERStory Makers is also part of EXPLORATHON, Scotland's contribution to European Researchers' Night.In 2022-23, EXPLORATHON was supported by the Engineering & Physical Sciences Research Council [grant number EP/X020894/1].Author contributions to contentMartina Čagalj conceived, planned, and recorded the video content. Kirsty Ross edited the video content to insert HERStory Maker credits, add subtitles, and maintain video length below Twitter/X limit of 2 mins and 20 secs, prior to scheduling the social media posts.</p
The role of data science in software development
No full textauthor: Martina WeberMasterarbeit Universität Innsbruck 201
The role of data science in software development
No full textauthor: Martina WeberMasterarbeit Universität Innsbruck 201
The role of data science in software development
No full textauthor: Martina WeberMasterarbeit Universität Innsbruck 201
Man kann nicht nicht vergleichen. Sprachvergleich und Sprachreflexion in einer integrierten Mehrsprachigkeitsdidaktik mit Englisch als Brückensprache
No full textPlurilinguism and plurilingual didactics have gained an important position in scientific discussion, even though interlingual and integrated approaches to teaching practice are still lacking. After a short description of various approaches, all based on language comparison and metalingual reflection, the author suggests adopting English as a bridge-language in plurilingual didactics, independent of the language family and languages studied. On the basis of various learner profiles, the author illustrates the benefit of using English as an element of language comparison and reflection in the learning process of other languages
Author Correction: Gluten consumption and inflammation affect the development of celiac disease in at-risk children
No full textThe original version of this Article contained an error in the spelling of the authors Renata Auricchio, Ilaria Calabrese, Martina Galatola, Donatella Cielo, Fortunata Carbone, Marianna Mancuso, Giuseppe Matarese, Riccardo Troncone, Salvatore Auricchio & Luigi Greco which were incorrectly given as Auricchio Renata, Calabrese Ilaria, Galatola Martina, Cielo Donatella, Carbone Fortunata, Mancuso Marianna, Matarese Giuseppe, Troncone Riccardo, Auricchio Salvatore & Greco Luigi. The original article has been corrected
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