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RESEARCH ARTICLE

Cellulose Nanocrystal-Enhanced Thermal-Sensitive

Hydrogels of Block Copolymers for 3D Bioprinting

Yuecheng Cui , Ronghua Jin , Yifan Zhang , Meirong Yu , Yang Zhou , Li-Qun Wang *
2
1,4
1
1
2
3
1 MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and
Engineering, Zhejiang University, Hangzhou 310027, P. R. China
2 Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou 310009, P. R. China
3 Hangzhou Regenovo Biotechnology Co. Ltd, Hangzhou Economic and Technological Development Area, Hangzhou
310018, P. R. China
4 Hangzhou Medsun Biological Technology Co., Ltd, Hangzhou Economic and Technological Development Area, Hangzhou
310018, P. R. China
Abstract: The hydrogel formed by polyethylene glycol-aliphatic polyester block copolymers is an ideal bioink and
biomaterial ink for three-dimensional (3D) bioprinting because of its unique temperature sensitivity, mild gelation
process, good biocompatibility, and biodegradability. However, the gel forming mechanism based only on hydrophilic-
hydrophobic interaction renders the stability and mechanical strength of the formed hydrogels insufficient, and cannot
meet the requirements of extrusion 3D printing. In this study, cellulose nanocrystals (CNC), which is a kind of rigid,
hydrophilic, and biocompatible nanomaterial, were introduced to enhance the hydrogels so as to meet the requirements
of extrusion 3D printing. First, a series of poly(ε-caprolactone/lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone/
lactide) (PCLA-PEG-PCLA) triblock copolymers with different molecular weights were prepared. The thermodynamic
and rheological properties of CNC-enhanced hydrogels were investigated. The results showed that the addition of CNC
significantly improved the thermal stability and mechanical properties of the hydrogels, and within a certain range, the
enhancement effect was directly proportional to the concentration of CNC. More importantly, the PCLA-PEG-PCLA
hydrogels enhanced by CNC could be extruded and printed through temperature regulation. The printed objects had high
resolution and fidelity with effectively maintained structure. Moreover, the hydrogels have good biocompatibility with a
high cell viability. Therefore, this is a simple and effective strategy. The addition of the hydrophilic rigid nanoparticles
such as CNC improves the mechanical properties of the soft hydrogels which made it able to meet the requirements of
3D bioprinting.
Keywords: Poly(ε-caprolactone/lactide)-b-poly (ethylene glycol)-b-poly(ε caprolactone/lactide); Thermal-sensitive
hydrogels; Three-dimensional bioprinting; Cellulose nanocrystal

*Correspondence to: Li-Qun Wang, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China;
lqwang@zju.edu.cn
Received: June 02, 2021; Accepted: August 03, 2021; Published Online: August 27, 2021
Citation: Cui Y, Jin R, Zhang Y, et al., 2021, Cellulose Nanocrystal-Enhanced Thermal-Sensitive Hydrogels of Block
Copolymers for 3D Bioprinting. Int J Bioprint, 7(4):397. http://doi.org/10.18063/ijb.v7i4.397

1. Introduction methods in this technology are diverse, and material
jetting, material extrusion, and vat polymerization
Three-dimensional (3D) bioprinting is a rapid additive bioprinting are commonly used [3-7] . Among them,
manufacturing technology which is used in the field of material extrusion bioprinting is capable of fabricating
tissue engineering [1,2] . As an emerging research direction, more scaled bio-scaffold compared with the other two
it has attracted widespread attention. The printing technologies, exhibiting more potential and prospect in

© 2021 Cui, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License, permitting distribution and
reproduction in any medium, provided the original work is cited.
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