posted on 2020-11-30, 22:34authored byZiwei Deng, Tianbao Qian, Fei Hang
Hydrogels have drawn extensive attention
due to their unique physical
and biological properties. However, the relatively low mechanical
strength and poor processability of hydrogels limit their applications.
Especially, the emerging 3D printing technology for nontoxic hydrogels
requires proper formability and controllable mechanical behaviors.
In this study, a new strategy to construct a novel double-network
biocompatible hydrogel from poly(ethylene glycol) diacrylate (PEGDA)
and short-chain chitosan (CS) via ionic–covalent cross-linking
is by a two-step method involving UV curing followed by immersion
in an anionic solution. The CS-based ionic network and PEGDA-based
covalent network as well as the hydrogen bonds between them jointly
induce excellent mechanical properties, which can be regulated by
changing the PEGDA/CS content and ionic cross-linking time. Compared
with conventional hydrogels, this mechanically optimized hydrogel
exhibits a superior elastic modulus (3.84 ± 0.4 MPa), higher
tensile strength (7.23 ± 0.2 MPa), and higher tensile strain
(162 ± 7%). Notably, its excellent printing capability through
the citrate anionic solution adjustment enables 3D printing with precision,
flexibility, and a complex inner structure by extrusion in air at
room temperature. In addition, a number of citrate ions existed in
the ionic network, giving the hydrogels good electrical conductivity.
Therefore, this printable, conductive, and tough hydrogel exhibits
potential for vascular engineering, cartilage tissue engineering,
and wearable device applications.