AccScience Publishing / IJB / Volume 9 / Issue 5 / DOI: 10.18063/ijb.750

Enzymatic post-crosslinking of printed hydrogels of methacrylated gelatin and tyramine-conjugated 8-arm poly(ethylene glycol) to prepare interpenetrating 3D network structures

Jia Liang1,2 Zhule Wang3 Andreas A. Poot2 Dirk W. Grijpma2 Piet J. Dijkstra2 Rong Wang2,3*
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1 Department of Neurosurgery, Stroke Center, Henan Provincial People’s Hospital, 450003, Henan, China
2 Department of Biomaterials Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
3 Department of Dentistry-Regenerative Biomaterials, Radboud University Medical Center, Philips van Leydenlaan 25, 6525 EX Nijmegen, The Netherlands
Submitted: 13 September 2022 | Accepted: 7 November 2023 | Published: 11 May 2023
(This article belongs to the Special Issue Additive Manufacturing of Functional Biomaterials)
© 2023 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( )

Methacrylated gelatin (GelMA) has been intensively studied as a 3D printable scaffold material in tissue regeneration fields, which can be attributed to its wellknown biological functions. However, the long-term stability of photo-crosslinked GelMA scaffolds is hampered by a combination of its fast degradation in the presence of collagenase and the loss of physical crosslinks at higher temperatures. To increase the longer-term shape stability of printed scaffolds, a mixture of GelMA and tyramine-conjugated 8-arm PEG (8PEGTA) was used to create filaments composed of an interpenetrating network (IPN). Photo-crosslinking during filament deposition of the GelMA and subsequent enzymatic crosslinking of the 8PEGTA were applied to the printed 3D scaffolds. Although both crosslinking mechanisms are radical based, they operate without interference of each other. Rheological data of bulk hydrogels showed that the IPN was an elastic hydrogel, having a storage modulus of 6 kPa, independent of temperature in the range of 10 – 40°C. Tensile and compression moduli were 110 kPa and 80 kPa, respectively. On enzymatic degradation in the presence of collagenase, the gelatin content of the IPN fully degraded in 7  days, leaving a stable secondary crosslinked 8PEGTA network. Using a BioMaker bioprinter, hydrogels without and with human osteosarcoma cells (hMG-63) were printed. On culturing for 21  days, hMG-63 in the GelMA/8PEGTA IPN showed a high cell viability (>90%). Thus, the presence of the photoinitiator, incubation with H2 O2 , and mechanical forces during printing did not hamper cell viability. This study shows that the GelMA/8PEGTA ink is a good candidate to generate cell-laden bioinks for extrusion-based printing of constructs for tissue engineering applications.

8-arm PEG
Enzymatic crosslinking

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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing