Iskanje po katalogu digitalne knjižnice

Opis: We present a scalable platform for the fabrication of multifunctional bioactive materials by integrating, polysaccharide-based matrices, green extraction and additive manufacturing. In this work, bioactive 3D-printed structures were fabricated using inks composed of nanofibrillated cellulose (NFC), alginate (Alg), and curcumin extracts. Bioactive compounds were efficiently recovered from turmeric via solvent-free supercritical carbon dioxide extraction, yielding up to 6.57 mg/100 g curcuminoids and 232.45 mg/100 g total phenols. The extracts exhibited robust antioxidant activity (DPPH• IC50: 23.24 mg/mL; ABTS+• IC50: 3.59 mg/mL) and broad-spectrum antimicrobial efficacy against Staphylococcus aureus, Escherichia coli, Candida albicans, and Pseudomonas aeruginosa (MIC: 9.38 mg/mL). Incorporation into NFC-Alg inks exhibited excellent shear-thinning properties suitable for direct-ink-writing 3D printing. Post-printing CaCl2 crosslinking further reinforced the hydrogel network, enhancing mechanical robustness and shape fidelity. The resulting constructs featured a highly porous, grid-like architecture with intricate surface morphology, highlighting significant potential for biomedical and tissue engineering applications.
Ključne besede: nanocellulose, alginate, curcumin extract, supercritical-CO2, antioxidant, antimicrobial properties, 3D-printing
Objavljeno v DKUM: 08.12.2025; Ogledov: 0; Prenosov: 3
Celotno besedilo (7,77 MB)

Opis: The design of ergonomic tool handles is crucial for user comfort and performance, yet conventional stiff materials often lead to uneven pressure distribution and discomfort. This study investigates the application of 3D-printed cellular metamaterials with tunable stiffness, specifically gyroid structures, to enhance the ergonomic and haptic properties of tool handles. We employed finite element analysis to simulate finger–handle interactions and conducted subjective comfort evaluations with participants using a foxtail saw with handles of varying gyroid infill densities and a rigid PLA handle. Numerical results demonstrated that handles with medium stiffness significantly reduced peak contact pressures and promoted a more uniform pressure distribution compared to the stiff PLA handle. The softest gyroid handle, while compliant, exhibited excessive deformation, potentially compromising stability. Subjective comfort ratings corroborated these findings, with medium-stiffness handles receiving the highest scores for overall comfort, fit, and force transmission. These results highlight that a plateau-like mechanical response of the 3D-printed cellular metamaterial handle, inversely bioinspired by human soft tissue, effectively balances pressure redistribution and grip stability. This bioinspired design approach offers a promising direction for developing user-centered products that mitigate fatigue and discomfort in force-intensive tasks.
Ključne besede: bioinspired design, product ergonomics, 3D printing, tool handle, finite element method, user comfort, cellular metamaterials
Objavljeno v DKUM: 03.11.2025; Ogledov: 0; Prenosov: 4
Celotno besedilo (2,85 MB)
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Opis: Skin bioprinting has the potential to revolutionize treatment approaches for injuries and surgical procedures, while also providing a valuable platform for assessing and screening cosmetic and pharmaceutical products. This technology offers key advantages, including flexibility and reproducibility, which enable the creation of complex, multilayered scaffolds that closely mimic the intricate microenvironment of native skin tissue. The development of an ideal hydrogel is critical for the successful bioprinting of these scaffolds with incorporated cells. In this study, we used a hydrogel formulation developed in our laboratory to fabricate a 3D-bioprinted skin model. The hydrogel composition was carefully selected based on its high compatibility with human skin cells, incorporating alginate, methyl cellulose, and nanofibrillated cellulose. One of the critical challenges in this process, particularly for its commercialization and large-scale production, is ensuring consistency with minimal batch-to-batch variations. To address this, we explored methods with which to preserve the physicochemical properties of the hydrogels, with a focus on freezing techniques. We validated the pre-frozen hydrogels’ printability, rheology, and mechanical and surface properties. Our results revealed that extended freezing times significantly reduced the viscosity of the formulations due to ice crystal formation, leading to a redistribution of the polymer chains. This reduction in viscosity resulted in a more challenging extrusion and increased macro- and microporosity of the hydrogels, as confirmed by nanoCT imaging. The increased porosity led to greater water uptake, swelling, compromised scaffold integrity, and altered degradation kinetics. The insights gained from this study lay a solid foundation for advancing the development of an in vitro skin model with promising applications in preclinical and clinical research.
Ključne besede: in vitro skin model, 3D printing, hydrogels, preclinical and clinical medicine
Objavljeno v DKUM: 28.07.2025; Ogledov: 0; Prenosov: 9
Celotno besedilo (4,94 MB)
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Opis: Cellulose and its derivatives are increasingly explored in biomedical applications due to their biocompatibility,biodegradability, and mechanical performance. In regenerative medicine, aerogel scaffolds with tunable morphology and compositionare highly valued for their ability to support tissue regeneration. Three-dimensional (3D) printing offers an effective method tofabricate aerogels with hierarchical pore structures, comprising interconnected macropores and mesopores, that are crucial for tissueengineering. For clinical use, 3D printing should ensure the structural integrity of printed structures and achieve a printing resolutionthat allows for customization. In this work, the X-aerogel technology, implemented via polyurea cross-linking, was applied to 3D-printed cellulose structures, thereby expanding the potential applications of both technologies. Specifically, 3D-printedmethylcellulose (MC) and MC doped with bacterial cellulose nanofiber (MCBCf) gels were cross-linked with an aliphaticpolyurea, yielding, after supercritical drying, the corresponding (X-MC and X-MCBCf) aerogels. Elaborate characterization withATR-FTIR, XPS, ToF-SIMS, N2 porosimetry, He pycnometry, and SEM confirmed the formation of polyurea on the biopolymerframework, reinforcing the structure and improving the mechanical properties without altering the morphology or texturalcharacteristics of the materials. A significant outcome of cross-linking with polyurea is the long-term stability of X-MC and X-MCBCf aerogels in water, in contrast to their native counterparts, and their capacity to absorb water up to 1800% w/w within only 2h. Preliminary biological evaluation of the materials, including in vitro (cell compatibility, hemolytic activity), in ovo (HET-CAM),and in vivo (A. salina model) tests, showed good cell viability, blood compatibility, and safety for living organisms. From afundamental materials perspective, the most important finding of this work is the disproportionally high stability of X-MC and X-MCBCf in physiological environments, achieved with only a minimal (almost undetectable) amount of cross-linking polyurea. Froman application standpoint, the findings of this study, collectively, position these aerogels as sustainable and promising candidates fortissue engineering scaffolds.
Ključne besede: 3D printing, aerogels, cellulose, methylcellulose, polyurea, tissue engineering, X-aerogels
Objavljeno v DKUM: 30.05.2025; Ogledov: 0; Prenosov: 12
Celotno besedilo (7,71 MB)

Opis: This study enhances the bioactivity of polycaprolactone (PCL) scaffolds for tissue engineering by functionalizing them with oxidized hyaluronic acid glycine-peptide conjugates to improve endothelial cell adhesion and growth. Hyaluronic acid was conjugated with a glycine-peptide to create a bioactive interface on PCL (static water contact angle, SCA(H2O): 98°). The scaffolds were fabricated using a melt extrusion 3D printing technique. The HA-glycine peptide conjugates were oxidized and immobilized on aminolyzed PCL via Schiff-base chemistry, introducing hydrophilicity (SCA(H2O): 21°), multiple functional groups, and a negative zeta potential (-12.04 mV at pH 7.4). A quartz crystal microbalance confirmed chemical conjugation and quantified the mass (8.5-10.3 mg m-2) of oxidized HA-glycine on PCL. The functionalized scaffolds showed enhanced swelling, improved mechanical properties (2-fold increase in strength, from 26 to 51 MPa), and maintained integrity during degradation. In-vitro experiments demonstrated improved endothelial cell adhesion, proliferation and viability, suggesting the potential for vascularized tissue constructs.
Ključne besede: 3D printing, polycaprolactone, hyaluronic acid
Objavljeno v DKUM: 19.03.2025; Ogledov: 0; Prenosov: 3
Celotno besedilo (9,50 MB)
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