Browsing by Subject "HYDROGELS"

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  • Sanz-Garcia, Andres; Sodupe-Ortega, Enrique; Pernia-Espinoza, Alpha; Shimizu, Tatsuya; Escobedo-Lucea, Carmen (2020)
    Three-dimensional (3D) bioprinting promises to be essential in tissue engineering for solving the rising demand for organs and tissues. Some bioprinters are commercially available, but their impact on the field of Tissue engineering (TE) is still limited due to their cost or difficulty to tune. Herein, we present a low-cost easy-to-build printhead for microextrusion-based bioprinting (MEBB) that can be installed in many desktop 3D printers to transform them into 3D bioprinters. We can extrude bioinks with precise control of print temperature between 2-60 degrees C. We validated the versatility of the printhead, by assembling it in three low-cost open-source desktop 3D printers. Multiple units of the printhead can also be easily put together in a single printer carriage for building a multi-material 3D bioprinter. Print resolution was evaluated by creating representative calibration models at different temperatures using natural hydrogels such as gelatin and alginate, and synthetic ones like poloxamer. Using one of the three modified low-cost 3D printers, we successfully printed cell-laden lattice constructs with cell viabilities higher than 90% after 24-h post printing. Controlling temperature and pressure according to the rheological properties of the bioinks was essential in achieving optimal printability and great cell viability. The cost per unit of our device, which can be used with syringes of different volume, is less expensive than any other commercially available product. These data demonstrate an affordable open-source printhead with the potential to become a reliable alternative to commercial bioprinters for any laboratory.
  • Sodupe-Ortega, Enrique; Sanz-Garcia, Andres; Pernia-Espinoza, Alpha; Escobedo-Lucea, Carmen (2018)
    Most of the studies in three-dimensional (3D) bioprinting have been traditionally based on printing a single bioink. Addressing the complexity of organ and tissue engineering, however, will require combining multiple building and sacrificial biomaterials and several cells types in a single biofabrication session. This is a significant challenge, and, to tackle that, we must focus on the complex relationships between the printing parameters and the print resolution. In this paper, we study the influence of the main parameters driven multi-material 3D bioprinting and we present a method to calibrate these systems and control the print resolution accurately. Firstly, poloxamer hydrogels were extruded using a desktop 3D printer modified to incorporate four microextrusion-based bioprinting (MEBB) printheads. The printed hydrogels provided us the particular range of printing parameters (mainly printing pressure, deposition speed, and nozzle z-offset) to assure the correct calibration of the multi-material 3D bioprinter. Using the printheads, we demonstrated the excellent performance of the calibrated system extruding different fluorescent bioinks. Representative multi-material structures were printed in both poloxamer and cell-laden gelatin-alginate bioinks in a single session corroborating the capabilities of our system and the calibration method. Cell viability was not significantly affected by any of the changes proposed. We conclude that our proposal has enormous potential to help with advancing in the creation of complex 3D constructs and vascular networks for tissue engineering.
  • Pitkänen, Leena M.; Heinonen, Marina; Mikkonen, Kirsi S. (2018)
    A growing population and concern over the sufficiency of natural resources for feeding this population has motivated researchers and industries to search for alternative and complementary sources of food ingredients and additives. Numerous plant species and parts of plants are explored as raw materials for food production. An interesting example is wood; to date, few wood-based additives or ingredients are authorized for food use. Wood hemicelluloses, such as softwood galactoglucomannans (GGM), constitute an abundant bioresource that shows a highly potential functionality in edible materials. Spruce GGM—“spruce gum”—acts as a multi-functional emulsion stabilizer, and it could be used in various processed food products, replacing less effective, conventional emulsifiers. Before new materials can be released onto the food market, their safety must be evaluated, according to the Novel Food regulation. This review focuses on the safety aspects that must be considered before polysaccharide- and phenolic-rich plant extracts can be awarded the status of authorized food ingredients. In this review, GGM is presented as a case study and examples are given of plant-based polysaccharides that are already authorized for food purposes. The legislation regarding Novel Food ingredients in Europe is also briefly reviewed.
  • Amirsadeghi, Armin; Jafari, Arman; Hashemi, Seyyedeh-Sara; Kazemi, Aboozar; Ghasemi, Younes; Derakhshanfar, Amin; Shahbazi, Mohammad-Ali; Niknezhad, Seyyed Vahid (2021)
    Wound infection is considered a significant challenge in skin injuries. Sprayable antibacterial wound dressings are interesting alternatives to their traditional counterparts because of their facile preparation, ease-of-use, and the possibility of topical delivery of antibacterial materials. Herein, novel sprayable antibacterial dressings are formulated and reported. The dressings were developed by in-situ formation of Ag-nanoparticles (Ag-NPs) using Persian gum (PG) as a carbohydrate polymer. Several tests were conducted to investigate the effect of polymer concentration on the sprayablity, biocompatibility, and antibacterial activity of the dressings (PG/Ag-NPs). Results showed that formulations up to 2 wt.% PG/Ag-NPs could be sprayed properly and form intact films. Antibacterial evaluations also showed biocidal activity of 1% PG/Ag-NPs against Pseudomonas aeruginosa and Staphylococcus aureus. Cytotoxicity and in vivo full-thickness wound healing evaluation confirmed that 1% PG/ Ag-NPs spray was safe and improved wound healing process. All the results confirmed the high potential of formulated sprayable dressings for wound repair.
  • Bertula, Kia; Martikainen, Lahja; Munne, Pauliina; Hietala, Sami; Klefström, Juha; Ikkala, Olli; Nonappa, Dr. (2019)
    Strain-stiffening is one of the characteristic properties of biological hydrogels and extracellular matrices, where the stiffness increases upon increased deformation. Whereas strain-stiffening is ubiquitous in protein-based materials, it has been less observed for polysaccharide and synthetic polymer gels. Here we show that agarose, that is, a common linear polysaccharide, forms helical fibrillar bundles upon cooling from aqueous solution. The hydrogels with these semiflexible fibrils show pronounced strain-stiffening. However, to reveal strain-stiffening, suppressing wall slippage turned as untrivial. Upon exploring different sample preparation techniques and rheological architectures, the cross-hatched parallel plate geometries and in situ gelation in the rheometer successfully prevented the slippage and resolved the strain-stiffening behavior. Combining with microscopy, we conclude that strain-stiffening is due to the semiflexible nature of the agarose fibrils and their geometrical connectivity, which is below the central-force isostatic critical connectivity. The biocompatibility and the observed strain-stiffening suggest the potential of agarose hydrogels in biomedical applications.
  • Fliervoet, Lies A. L.; Lisitsyna, Ekaterina S.; Durandin, Nikita A.; Kotsis, Ilias; Maas-Bakker, Roel F. M.; Yliperttula, Marjo; Hennink, Wim E.; Vuorimaa-Laukkanen, Elina; Vermonden, Tina (2020)
    Combining multiple stimuli-responsive functionalities into the polymer design is an attractive approach to improve nucleic acid delivery. However, more in-depth fundamental understanding how the multiple functionalities in the polymer structures are influencing polyplex formation and stability is essential for the rational development of such delivery systems. Therefore, in this study the structure and dynamics of thermosensitive polyplexes were investigated by tracking the behavior of labeled plasmid DNA (pDNA) and polymer with time-resolved fluorescence spectroscopy using fluorescence resonance energy transfer (FRET). The successful synthesis of a heterofunctional poly(ethylene glycol) (PEG) macroinitiator containing both an atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) initiator is reported. The use of this novel PEG macroinitiator allows for the controlled polymerization of cationic and thermosensitive linear triblock copolymers and labeling of the chain-end with a fluorescent dye by maleimide-thiol chemistry. The polymers consisted of a thermosensitive poly(N-isopropylacrylamide) (PNIPAM, N), hydrophilic PEG (P), and cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, D) block, further referred to as NPD. Polymer block D chain-ends were labeled with Cy3, while pDNA was labeled with FITC. The thermosensitive NPD polymers were used to prepare pDNA polyplexes, and the effect of the N/P charge ratio, temperature, and composition of the triblock copolymer on the polyplex properties were investigated, taking nonthermosensitive PD polymers as the control. FRET was observed both at 4 and 37 degrees C, indicating that the introduction of the thermosensitive PNIPAM block did not compromise the polyplex structure even above the polymer's cloud point. Furthermore, FRET results showed that the NPD- and PD-based polyplexes have a less dense core compared to polyplexes based on cationic homopolymers (such as PEI) as reported before. The polyplexes showed to have a dynamic character meaning that the polymer chains can exchange between the polyplex core and shell. Mobility of the polymers allow their uniform redistribution within the polyplex and this feature has been reported to be favorable in the context of pDNA release and subsequent improved transfection efficiency, compared to nondynamic formulations.