Collagen-Based Thiol–Norbornene Photoclick Bio-Ink with Excellent Bioactivity and Printability

Abstract

As the essential foundation of bioprinting technology, cell-laden bio-ink is confronted with the inevitable contradiction between printability and bioactivity. For example, type I collagen has been widely applied for its excellent biocompatibility; however, its relatively low self-assembly speed restricts the performance in high-precision bioprinting of cell-laden structures. In this study, we synthesize norbornene-functionalized neutral soluble collagen (NorCol) by the reaction of acid-soluble collagen (Col) and carbic anhydride in the aqueous phase. NorCol retains collagen triple-helical conformation and can be quickly orthogonally cross-linked to build a cell-laden hydrogel via a cell-friendly thiol-ene photoclick reaction. Moreover, the additional carboxyl groups produced in the reaction of carbic anhydride and collagen obviously improve the solubility of NorCol in neutral buffer and miscibility of NorCol with other polymers such as alginate and gelatin. It enables hybrid bio-ink to respond to multiple stimuli, resulting in continuous cross-linked NorCol networks in hybrid hydrogels. For the first time, the collagen with a triple helix structure and gelatin can be mixed and printed, keeping the integrity of the printed construct after gelatin’s dissolution. The molecular interaction among giant collagen molecules allows NorCol hydrogel formation at a low concentration, which leads to excellent cell spreading, migration, and proliferation. These properties give NorCol flexible formability and excellent biocompatibility in temperature-, ion-, and photo-based bioprinting. We speculate that NorCol is a promising bio-ink for emerging demands in tissue engineering, regenerative medicine, and personalized therapeutics.

Bone Regeneration Using MMP-Cleavable Peptides-Based Hydrogels

“…Therefore, gelatin could employ an NB group using 5-norbornene-2-carboxylic acid in the reaction of the carboxylic acid and the primary amines [ 82 ]. The norbornene derivant could also be utilized in NB group insertion; Guo et al synthesized norbornene-collagen that was obtained from acidic collagen after reacting with carbic anhydride [ 83 ].…”

“…For example, collagen was found to possess many inherently useful properties for regenerative medicine, and it has also been widely used in the 3D printing field. Guo et al developed a norbornene-functionalized collagen-based hydrogel, which acted as a bio-ink and exhibited cell viability, spreading and proliferation properties [ 83 ]. The printability property, which is critical for 3D printing, was tested using different printing methods.…”

“…The printability property, which is critical for 3D printing, was tested using different printing methods. As a result, it was demonstrated that the norbornene-functionalized collagen bio-ink showed potential prospects in bioprinting [ 83 ].…”

Bidirectional Differentiation of Human-Derived Stem Cells Induced by Biomimetic Calcium Silicate-Reinforced Gelatin Methacrylate Bioink for Odontogenic Regeneration

“…During printing, the biomaterial was dispensed by a deposition system controlled by a computer, thus making it possible to control the geometries and obtain precise deposition of the biomaterials. However, one disadvantage of extrusion-based printing is that the biomaterial must have low viscosity to avoid clogging of the needle and yet be controlled at the proper sol-gel temperature range for the proper extrusion of the biomaterials [35]. Given the need for fitting bioink printability and mechanical behaviors of the final scaffolds, CS containing GelMa bioink have been proven to have good potential for use in bioprinting towards possible tissue regeneration applications [36].…”

“…Biomedicines 2021, 9, x FOR PEER REVIEW 8 of 17 [35]. Given the need for fitting bioink printability and mechanical behaviors of the final scaffolds, CS containing GelMa bioink have been proven to have good potential for use in bioprinting towards possible tissue regeneration applications [36].…”