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ORIGINAL ARTICLE

Preheating of Gelatin Improves its Printability with

Transglutaminase in Direct Ink Writing 3D Printing

Justin Jia Yao Tan 1,2† , Cheng Pau Lee 1,2† , Michinao Hashimoto 1,2*
1 Pillar of Engineering Product Development, Singapore University of Technology and Design, 8 Somapah Road, Singapore
487372, Singapore
2 SUTD-MIT International Design Centre, Singapore University of Technology and Design, 8 Somapah Road, Singapore
487372, Singapore
†These authors contributed equally to this paper.

Abstract: Gelatin and transglutaminase (TG) ink is increasingly popular in direct ink writing three-dimensional (3D)
printing of cellular scaffolds and edible materials. The use of enzymes to crosslink gelatin chains removes the needs for
toxic crosslinkers and bypasses undesired side reactions due to the specificity of the enzymes. However, their application
in 3D printing remains challenging primarily due to the rapid crosslinking that leads to the short duration of printable
time. In this work, we propose the use of gelatin preheated for 7 days to extend the duration of the printing time of the
gelatin ink. We first determined the stiffness of freshly prepared gelatin (FG) and preheated gelatin (PG) (5 – 20% w/w)
containing 5% w/w TG. We selected gelatin hydrogels made from 7.5% w/w FG and 10% w/w PG that yielded similar
stiffness for subsequent studies to determine the duration of the printable time. PG inks exhibited longer time required
for gelation and a smaller increase in viscosity with time than FG inks of similar stiffness. Our study suggested the
advantage to preheat gelatin to enhance the printability of the ink, which is essential for extrusion-based bioprinting and
food printing.

Keywords: Gelatin, Transglutaminase, Direct ink writing, Extrusion-based 3D printing, Printability, Preheating

*Corresponding Author: Michinao Hashimoto, Pillar of Engineering Product Development, Singapore University of Technology and Design, 8
Somapah Road, Singapore 487372, Singapore; hashimoto@sutd.edu.sg

Received: April 06, 2020; Accepted: June 07, 2020; Published Online: September 08, 2020
Citation: Tan JJY, Lee CP, Hashimoto M, Preheating of Gelatin Improves its Printability with Transglutaminase in Direct Ink
Writing 3D Printing, Int J Bioprint, 6(4): 296. DOI: 10.18063/ijb.v6i4.296.

1 Introduction express the characteristics of tissue markers and
spatial orientations as native human organs .
[1]
This paper discusses the effects of preheating Strategies have been developed to improve
gelatin on its printability through direct ink the resolution, shape fidelity, and complexity
writing (DIW) three-dimensional (3D) printing.
Recent developments in 3D printing and additive of these 3D printed organs. Examples include
manufacturing have extended into the fields delaying cell sedimentation within the bioink
of tissue engineering [1,2] , sensing , and food through the addition of non-adhesive polymers or
[3]
[2]
engineering [4,5] . In the field of tissue engineering, weakly crosslinked hydrogels . In sensing, 3D
anatomical replicas of human organs such as skin, printing has been used to fabricate multi-material,
heart, lung, kidney, and liver have been printed. multifunctional stretchable electronic devices,
These 3D printed organs have been shown to ranging from wearable electronics, energy

© 2020 Tan, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License
(http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original
work is properly cited.
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