UPenn Researchers Using Jammed Microgels as 3D Bioprinting Inks
A trio of researchers from the University of Pennsylvania have published a paper, titled “Jammed Microgel Inks for 3D Printing Applications,” on their use of jammed microgels as inks for bioprinting, in order to address the various limitations of 3D bioprinting with hydrogels. Researchers and scientists use 3D bioprinting to organize materials and cells into 3D structures, and while it can do amazing things, the technology still has a lot of challenges, like materials restrictions and achieving the correct resolution and stability for printed constructs. While soft hydrogel materials are often used in tissue engineering, thanks to tunable biochemical and biophysical properties, it’s hard to print them without using some sort of additive or modification.
The microparticles found in jammed systems are packed pretty densely, and physical interactions with surrounding particles immobilize them. This results in macroscopic materials that behave as solids, until movement is induced by applied force.
Jammed microgels work as bioinks because they allow cross‐linked hydrogel particles to be formed as an aggregate bulk, which can then be extruded as a stable filament without using any other material or having to engineer any interparticle interactions. The researchers formed microgel inks through the use of microfluidic devices.
The team used norbornene‐modified hyaluronic acid (NorHA), poly(ethylene glycol) diacrylate (PEGDA), and agarose to make their microgels, which definitely displayed the kinds of rheological properties important for 3D printing, such as shear-thinning behavior, elastic response at low strains, and the ability to flow during extrusion and stabilize quickly after deposition. A modified Revolution XL 3D printer was used to fabricate the microgels into a four-layer lattice.
Mechanical forces disrupted the 3D printed structures as expected, so the team used post‐cross‐linking to chemically link the particles together.
Additionally, when the printed and post‐cross‐linked cuboid structures were placed in cell culture medium, they held their dimensions and structure for a whole week, and the “compressive moduli of printed constructs” was increased by introducing interparticle bonds to post‐cross‐linking. This happened at a lower value than hydrogels that are made of the same formulation used to make microgels; when combined, these results that it’s possible to 3D print microgel inks, “as the jammed ink properties support printing and short‐term stability.”
The research shows that microgel inks can definitely be used to 3D print heterogeneous structures without damaging any cells.
Co-authors of the paper are Christopher B. Highley, Kwang Hoon Song, Andrew C. Daly, and Jason A. Burdick.
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October 31, 2018 at 05:06PM