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composed of DCPD and OCP, along with a small High-resolution Multimaterial Fabrication for Digital Light
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enhanced the mechanical, physiological, and 3D Printing: The Relevance of Materials Affinity on the
biological characteristics of the pure hydrogel, Boundary Interface Performance. Addit Manuf, 23:45–52.
suggesting its great potential as a biomaterial for DOI: 10.1016/j.addma.2018.06.027.
various biomedical applications. In particular, 4. Jang TS, Jung HD, Pan HM, et al., 2018, 3D Printing
the proposed printing approach allowed multi- of Hydrogel Composite Systems: Recent Advances in
phase gradient material printing with a single Technology for Tissue Engineering. Int J Bioprinting, 4:126.
nozzle system, avoiding any issues caused by 5. Jeong SH, Koh YH, Kim SW, et al., 2016, Strong
the introduction of materials with differences and Biostable Hyaluronic Acid-calcium Phosphate
in printability and mechanical stability. Taken Nanocomposite Hydrogel via In Situ Precipitation Process.
together, our results suggest that designing Biomacromolecules, 17:841–51. DOI: 10.1021/acs.
and modifying the printing materials coupled biomac.5b01557.
with in situ post-printing functionalization and 6. Wust S, Godla ME, Muller R, et al., 2014, Tunable Hydrogel
hybridization in reactive viscoplastic matrices, our Composite with Two-step Processing in Combination
approach can accelerate the 3D printing of various with Innovative Hardware Upgrade for Cell-based Three-
functional or hybridized gradient biomaterials dimensional Bioprinting. Acta Biomater, 10:630–40. DOI:
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Conflicts of interest and funding
hydrogel Composites: Concept, Design, and Applications
No conflicts of interest were reported by of These Promising, Multi-functional Materials. Adv Sci
all authors. This research was supported by (Weinh), 2:1400010. DOI: 10.1002/advs.201400010.
Nanyang Technological University Start up grant, 8. Gaharwar AK, Schexnailder PJ, Dundigalla A, et al., 2011,
and A*STAR Advanced Manufacturing and Highly Extensible Bio-nanocomposite Fibers. Macromol
Engineering Individual Research Grants grant Rapid Commun, 32:50–7. DOI: 10.1002/marc.201000556.
A1983c0031 from A*STAR. 9. Leach JB, Bivens KA, Patrick CW, et al., 2003,
Photocrosslinked Hyaluronic Acid Hydrogels: Natural,
Author contributions Biodegradable Tissue Engineering Scaffolds. Biotechnol
Bioeng, 82:578–89. DOI: 10.1002/bit.10605.
Chen S. designed and performed the experiments, 10. Xu X, Jha AK, Harrington DA, et al., 2012, Hyaluronic
data analysis, and drafted the manuscript. Jang T.S. Acid-based Hydrogels: From a Natural Polysaccharide to
and Jung H.D. conducted SEM/TEM imaging, Complex Networks. Soft Matter, 8:3280–94. DOI: 10.1039/
XRD and EDS analyses of hydrogel samples. c2sm06463d.
Chen S., Pan, M, and Sia M.W performed cell tests. 11. Kisiel M, Martino MM, Ventura M, et al., 2013, Improving
Chong M. and Wang D. designed and supervised the Osteogenic Potential of BMP-2 with Hyaluronic Acid
the in vitro cell experiments. Song J designed the Hydrogel Modified with Integrin-specific Fibronectin
experiments and supervised the whole research. Fragment. Biomaterials, 34:704–12. DOI: 10.1016/j.
All authors have read the manuscript and given biomaterials.2012.10.015.
approval to the final version.
12. Li QH, Li M, Zhu PZ, et al., 2012, In Vitro Synthesis of
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