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    Biomaterials

    Solvent-cast 3D printed polymeric scaffolds: biocompatibility and mechanical properties

    (C-92) Solvent-cast 3D printed polymeric scaffolds: biocompatibility and mechanical properties

    Friday, October 13, 2023
    9:30 AM – 10:30 AM PDT
    Location: Exhibit Hall - Row C - Poster # 92
    Introduction:: Tissue engineering (TE) is a fast-growing field aimed at repairing tissues following injury or disease. Biomaterials are typically used to provide mechanical support to cells and tissues during tissue regeneration [1]. Scaffolds composed of biodegradable polymers can be  resorbed by the body as the  tissue heals [1]. This approach addresses limitations with using donor tissue or non-degradable materials, such as high cost, poor tissue-material integration, and risk of further damage to existing tissue[2]. The aim of this study was to characterize solvent-cast 3D-printed scaffolds composed of two medical-grade biodegradable polymers, Lactoprene® and Caproprene® (Poly-Med Inc),. Solvent-cast 3D printing involves dissolving a polymer in a volatile solvent, which evaporates during extrusion to leave behind a solid polymer filament. This fabrication technique enables us to print with a wide range of polymers with high resolution. Here, we characterized the mechanical properties of the 3D-printed filaments and cultured fibroblasts in 3D-printed scaffolds.

    Materials and Methods::

    Lactoprene® and Caproprene®  were dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol at 650 mg/mL and 500 mg/mL, respectively, in printing cartridges. Inks were mixed on a shaker for 48 hours and then stored for 24 hours without agitation before printing using a customized fluid dispensing robot (Nordson EFD EV Series). Filament arrays (25 filaments, 60 mm in length) for tensile testing were printed on a glass slide. Arrays (4 inks/sample group, 1-2 arrays/ink) were mechanically tested using a Zwick/Roell Tensile Tester with a 100 N load cell at a rate of 25 mm/min. Data for each ink was averaged and analyzed using an unpaired T-test. Scaffolds (17 mm x 17 mm, 14 layers, 260 µm filament spacing) were printed onto a glass slide using a 32G needle at a print pressure of 70 psi and line speed of 0.4 mm/s for the first layer and 0.2 mm/s for all following layers. Scaffold punches (3 mm diameter) were used for in vitro studies. Scaffolds were sterilized with 70% ethanol and pre-treated with 0.1% bovine serum albumin (BSA) in phosphate-buffered saline (PBS) before pinning to Sylgard-coated wells. NIH 3T3 mouse fibroblasts were seeded onto scaffolds (~20,000 cells/scaffold) and incubated at 37ºC and 5% CO2 with media changes every two days. Cell-seeded scaffolds were dehydrated using ethanol and fixed using 2% glutaraldehyde in PBS. All constructs were sputter-coated with iridium and imaged using a Hitachi 3500 Scanning Electron Microscope.



    Results, Conclusions, and Discussions:: Results and Discussion

    Caproprene® and Lactoprene® were successfully printed using solvent-cast 3D printing. Tensile testing showed that Lactoprene® filaments had a significantly higher modulus compared to Caproprene® filaments (Fig. 1A). SEM images showed differences in scaffold morphology. Caproprene® scaffolds had smaller filaments compared to Lactoprene® scaffolds (Fig. 1B).  Fibroblasts were successfully seeded on both scaffolds.Cells were detected near the surface of Caproprene® scaffolds at 24 hours and appeared to migrate into the scaffold at Day 7. Lactoprene® scaffolds showed a higher number of cells near the surface at both 24 hours and 7 days compared to Caproprene® scaffolds. These data indicate both scaffolds are suitable for tissue engineering applications. 




    Conclusions


    This work showed that medical-grade Caproprene® and Lactoprene® can be solvent-cast 3D printed into scaffolds for tissue engineering. Lactoprene® filaments showed a significantly higher tensile modulus compared to Caproprene®, illustrating how the scaffolds can be tailored for different applications. Cells were successfully seeded on the 3D-printed scaffolds and remained associated with the scaffolds for up to a week. Future studies will include scaffold mechanical testing and robust cell experiments to quantify cell viability.  



    Acknowledgements (Optional): :

    References (Optional): :

    [1] Hollister, S. J. (2005). Porous scaffold design for tissue engineering. Nature Materials, 4(7), 518–524. 


    https://doi.org/10.1038/nmat1421 




    [2] Hutmacher, D. W., Goh, J. C., & Teoh, S. H. (2001). An introduction to biodegradable materials for 


    tissue engineering applications. Annals of the Academy of Medicine, Singapore, 30(2), 183–191.




    [3] Tolbert, J. W., Hammerstone, D. E., Yuchimiuk, N., Seppala, J. E., & Chow, L. W. 


    (2021). Solvent‐cast 3D printing of biodegradable polymer scaffolds. Macromolecular Materials and Engineering, 306(12), 2100442. https://doi.org/10.1002/mame.202100442