Bioprinting of Thermoresponsive Hydrogels for Next Generation Tissue Engineering: A Review

Abstract

Bioprinting is a breakthrough technology that integrates living cells, biomaterials, and a robotic dispensing system to create complex structures that mimic original tissues and organs. One of the main components of bioprinting is bioink and hydrogel is essential in bioink formulation. In bioprinting, hydrogel should have good biocompatibility, provide good resolution, and have sufficient mechanical strength to support printed structures. Recently, thermoresponsive hydrogels have gained more and more attention due to their unique characteristic of tunable sol-gel (liquid to solid phase) transition when temperature is changed, and many biomedical applications from drug delivery devices to tissue scaffolds have demonstrated the potentials of bioprinted thermosresponsive constructs. In this review, we discuss bioprintable thermoresponsive hydrogels with a particular focus on their gelation mechanisms, fabrication strategies using bioprinter and applications. The future prospects of the bioprinting-based use of thermoresponsive hydrogels for next generation tissue engineering have also been discussed.

Roles of support materials in 3D bioprinting – Present and future

“…However, this technique needs precision control in temperature in addition to positional control. Gelatin is thermo-responsive which will start to melt when the temperature is above 30 °C [2] . Therefore, temperature control is critical for "FRESH".…”

“…ioprinting is an emerging technology that shows potential for regenerative medicine and other biomedical applications [1][2][3] . Unlike other 3D printing techniques which print non-living materials, bioprinting incorporates living materials during the printing process.…”

“…The viscosities of both hydrogels are low at the human body temperature (or before crosslinking stage). This may favor direct printing of cell-hydrogel suspensions without any change in environment or equipment such as temperature control unit [2,8] , but it is difficult to print them into 3D shapes without using strength enhancement strategy (e.g. chemical crosslinking or adding thickener).…”

“…Therefore, at the current stage, bioprinting of complex hollow structures that can completely mimic human's vascular systems or hollow organs such as heart or kidney is very challenging. Single material printing will not be sufficient to provide all the required properties (including biocompatibility, mechanical integrity and printability) [1][2][3][4][5][6][7][8][9] B for bioprinted 3D complex hollow structures.…”

3D Printing/Interfacial Polymerization Coupling for the Fabrication of Conductive Hydrogel

“…3D printing is an additive manufacturing (AM) process that enables to construct 3D objects directly from a digital model. It has received a great deal of attention from a diverse range of fields including electronics, biomedics and regenerative medicine, and microfluidics . Objects are constructed layer‐by‐layer, enabling the creation of complex parts with tailored morphology and functionality .…”