Bioprinting with hydrogels
Tags: 3D Bioprinting
4 tips to avoid common issues in hydrogel printing
3D printing is now widely applied in the electronics, automotive and aerospace industries, as well as in medical engineering. Due to its ability to provide high precision, and with increasingly convenient operation, applications of 3D printing continue to expand into new areas. In recent years, this technology has been also used in tissue engineering.
Hydrogels are one of the preferred biomaterials for 3D bioprinting applications because of their good biocompatibility and printability. It has been shown that the 3D environment of a cell helps to determine its morphology and growth characteristics after printing, and it is therefore expected that the native environment of a given cell type might be mimicked better using hydrogel bioinks.
Current research topics in 3D bioprinting include how to design new hydrogel bioinks, how to vascularize printed organs, and how to construct a suitable culture environment for organ functionalization. However, in order to print structures of clinically relevant sizes, it is important to know how to control the bioprinting fidelity and speed of bio fabrication. In the following, we provide you with strategies on how to avoid the most common issues faced when 3D bioprinting with hydrogels.
Choosing the right print parameters
Optimising print parameters purely on the basis of print fidelity may not provide conditions which support high cell viability. Decreasing nozzle diameter and increasing print pressure tends to give high accuracy when printing using extrusion-based techniques, however these conditions also increase the shear stress experienced by cells contained within the bioink. For most applications, a balance should be struck between conditions which favour print performance and those which favour high cell viability.
Applying the right strategy to avoid sharp angle printing issue
Sharp angle printing can be problematic when working with any bioink. The issue can be addressed by one of the following strategies. The first method is avoiding the sharp angle in the printing path generation. The second method is reducing the extrusion rate in this area by half of that used elsewhere in the printed structure. If the nozzle is extruded by a motor, the extrusion rate can be easily controlled by the motor speed. The overlap can be released with double moving speed.
In printing of lattice structures, the overlapped hydrogel layers can diffuse due to gravity. Due to the diffusion phenomenon, the pore formed during the print would radially narrow along the second hydrogel layer line but would not change axially. However, the first layer would not be affected. With an increase of line distance in the lattice, the diffusion rate drops quickly, and the fusion can be mitigated.
Hydrogels might support 3D bioprinting better than their substitutes by providing exceptional printability with good cell viability. However, a few of them require special environment circumstances, such as long gelation time, control of gelation temperature, pH changes or UV light to function properly. For instance, the crosslinking or gelation of collagen requires a minimum of 30 mins for gelation at 370C. Hence, the usage of collagen directly in 3D printing is tough. At Biogelx, we are experts in peptide-based hydrogels. Our novel 3D products form a nanofibrous network, mimicking the extracellular-matrix which supports cell growth, signalling, and proliferation. Our gels have been applied in 3D cell culture and bioprinting applications. The BiogelxTM-Inks are easy to work with. You can stop using light or chemical crosslinking, and you do not need a high temperature to make the gels printable.
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Source: He, Y. et al. Research on the printability of hydrogels in 3D bioprinting. Sci. Rep. 6, 29977; doi: 10.1038/srep29977 (2016).
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