Research

Researchers create free-form tissue structures with volumetric 3D bioprinting process

A team from the University Medical Center (UMC) Utrecht and École polytechnique fédérale de Lausanne (EPFL), Switzerland, have developed a volumetric 3D bioprinting process inspired by visible light projection that creates free-form tissue structures.

As stated by the study published in Advanced Materials, current bioprinting is based on layer‐by‐layer deposition and assembly of repetitive building blocks, such as cell‐laden hydrogel fibers or cellular aggregates. 

“The scalability of these additive manufacturing technologies is limited by their printing velocity, as lengthy biofabrication processes impair cell functionality,” the paper states.

“Volumetric bioprinting permits the creation of geometrically complex, centimeter‐scale constructs at an unprecedented printing velocity, opening new avenues for upscaling the production of hydrogel‐based constructs for application in tissue engineering, regenerative medicine, and soft robotics.”

Volumetric 3D bioprinting process fabricating a building model. Clip via UMC/EPFL.
Volumetric 3D bioprinting process fabricating a building model. Clip via UMC/EPFL.

Volumetric 3D bioprinting

According to the researchers, complex architectural tissue structures hold great potential for new cell‐instructive implants as they can enable regeneration within the body. Present 3D bioprinting processes can limit the the creation of structures with hollow features and overhangs.

The volumetric 3D bioprinting method involves a cylindrical container filled with cell‐laden photoresponsive hydrogel connected to a rotating platform. A series of 2D patterns is projected onto the cylinder triggering polymerization. This scaffold-free 3D bioprinting process was used to manufacture several models based on CT data in a time frame of tens of seconds.

“These dynamic light patterns are displayed into the build volume by irradiating a DLP modulator with a 405 nm laser source,” the study explains. “We demonstrated the possibility to print free‐floating parts without the need for sacrificial support materials or two‐photon polymerization approaches.”

“The freedom of design provided by volumetric bioprinting approaches permits the production of such actuators through the direct fabrication of movable or articulating parts.”

A) The cell‐laden gelRESIN reservoir connected to a rotating platform, B) a schematic of tomographic projections used to print the human auricle model, and C) a rendering of the resulting printed hydrogel structure. Image via UMC/EPFL.
A) The cell‐laden gelRESIN reservoir connected to a rotating platform, B) a schematic of tomographic projections used to print the human auricle model, and C) a rendering of the resulting printed hydrogel structure. Image via UMC/EPFL.

Layer-free 3D bioprinted structures

Hydrogel‐based ball‐and‐cage fluidic valves were developed using this method which are used in complex tissue structures. The printed ball and cage valves were connected at both ends to silicone tubing and was noted to be fabricated at a rapid speed.

The researchers concluded, “The rapid speed of volumetric bioprinting is an important benefit for the production of tissues and disease models. It is hoped that this capability can complement and even reduce animal testing in the intermediate phases of drug development, leading to lower development costs and fewer ethical issue.”

Volumetric Bioprinting of Complex Living‐Tissue Constructs within Seconds” is co-authored by Paulina Nuñez Bernal, Paul Delrot, Damien Loterie, Yang Li, Jos Malda, Christophe Moser, and Riccardo Levato. 

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Featured image shows the volumetric 3D bioprinting process fabricating a building model. Clip via UMC/EPFL.

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