Improving alginate printability for biofabrication: establishment of a universal and homogeneous pre-crosslinking technique

Abstract

Many different biofabrication approaches as well as a variety of bioinks have been developed by researchers working in the field of tissue engineering. A main challenge for bioinks often remains the difficulty to achieve shape fidelity after printing. In order to overcome this issue, a homogeneous pre-crosslinking technique, which is universally applicable to all alginate-based materials, was developed. In this study, the Young’s Modulus after post-crosslinking of selected hydrogels, as well as the chemical characterization of alginate in terms of M/G ratio and molecular weight, were determined. With our technique it was possible to markedly enhance the printability of a 2% (w/v) alginate solution, without using a higher polymer content, fillers or support structures. 3D porous scaffolds with a height of around 5 mm were printed. Furthermore, the rheological behavior of different pre-crosslinking degrees was studied. Shear forces on cells as well as the flow profile of the bioink inside the printing nozzle during the process were estimated. A high cell viability of printed NIH/3T3 cells embedded in the novel bioink of more than 85% over a time period of two weeks could be observed.

In situ bone regeneration with sequential delivery of aptamer and BMP2 from an ECM-based scaffold fabricated by cryogenic free-form extrusion

“…Three-dimensional (3D) bioprinting, an emerging biofabrication technology, has provided unprecedented opportunities for the treatment of critical-sized bone defects [ [2] , [3] , [4] , [5] ]. Recently, a variety of 3D-printed materials were developed for bone repair, including metals, ceramics, or polymers such as titanium, hydroxyapatite (HA) and poly (ϵ-caprolactone) (PCL) [ [6] , [7] , [8] ]. However, the use of these scaffolds was limited by their inability to mimic the unique microenvironmental cues of the natural bone extracellular matrix [ 9 , 10 ].…”

Development of Bioinspired Functional Chitosan/Cellulose Nanofiber 3D Hydrogel Constructs by 3D Printing for Application in the Engineering of Mechanically Demanding Tissues

“…A relatively limited number of biopolymer hydrogels are available as bioinks. Among them, the alginate-based systems are the most investigated ones [12], which have been tested for viability of fibroblasts, stem cells, chondrocytes, osteogenic activity support, neural tissue construction, etc. [13].…”

Comparison of Hydrogels for the Development of Well-Defined 3D Cancer Models of Breast Cancer and Melanoma

“…Variations of the different hydrogels in this study have already been used for extrusion-based 3D printing. Although alginate itself has poor printing properties due to low shape fidelity, a pre-crosslinking step with CaCO 3 and D-Glucono-δ-lactone can significantly improve the printing results without increasing the polymer density [64]. Due to the gelation properties of gelatin, ADA-GEL has also been shown to be printable [65].…”