Scientists Develop 3D Material That Mimics Biological Tissue

This up-close view illustrates the structure of the replicated humanlike 3D tissue. (Photo courtesy of Chris Yakacki)

(CN) — A feat once thought to be impossible, researchers announced Monday the creation of a 3D-printable material that can fully mimic real biological tissue.

Of the numerous biological components humans and other creatures are equipped with to aid their survival, biological tissue is arguably one of the most useful. Biological tissue is essentially an interconnected network of cells that work together towards a shared biological purpose, such as to give some organs much-needed shape and protection.

Take, for instance, the cartilage found in the human knee. This biological tissue has adapted and evolved over countless generations to perfectly suit the needs of that particular part of the body, a material that is strong enough to withstand the weight and pressure of the human body, but soft enough to cushion those joints from strenuous activity.

Researchers have long struggled to properly replicate biological tissue due to its cellular complexity. While evolution may have been capable of producing such tissue over the course of Earth’s natural history, creating a man-made substitute has proven to be a difficult challenge.

Scientists from the University of Colorado Denver and the Southern University of Science and Technology in China announced in this week’s Advanced Materials journal that they have changed that reality.

Led by mechanical engineer professor Chris Yakacki while working from the Smart Materials and Biomechanics Lab at CU Denver, researchers have learned how to use a 3D-printing process known as digital-light processing to create a special material that can be used to believably and fully replicate natural biological tissue.

The design is based largely on the usage of liquid crystal elastomers, which is a certain kind of soft material well known for its varied uses, exceptional elasticity and a unique ability to dispel significant amounts of energy.

Yakacki was already quite familiar with these crystals before this breakthrough, as he was previously applauded for his work in transforming how they could be used in manufacturing and development processes. He has even received some funding to help work LCEs into shock absorbers for football helmets.

But despite the potential of these materials, getting them to actually work the way researchers wanted them to was no easy task. Particularly given, scientists say, that the materials have previously be used largely to create either big objects with small detail or virtually microscopic objects with high detail.

“Everyone’s heard of liquid crystals because you stare at them in your phone display,” Yakacki said with the release of the study “And you’ve likely heard of liquid crystal polymers because that’s exactly what Kevlar is. Our challenge was to get them into soft polymers, like elastomers, to use them as shock absorbers. That’s when you go down the layers of complexity.”

Despite this challenges, Yakacki and researchers explored new ways to bend the material toward their goals.

This process began by creating a special resin, one that bears a striking resemblance to honey, that can form photopolymer layers when the resin is struck by an ultraviolet light. This altered resin and its layers form an elastomer that is both strong and soft, workable and durable and can be printed into a variety of special structures.

Researchers tested the material with a number of designs, such as a miniature but intricately detailed lotus flower and even an entire spinal fusion cage prototype.

The results were astonishingly impressive. The combination of their printing techniques and the special honey-like resin created final products that were vastly superior and more durable than other commercially available alternatives.

Yakacki believes that based on such promising results, the applications for this technology to be used for biological tissue could be tremendous. He is particularly enthusiastic about what this breakthrough could mean for the human spine, a bodily component riddled with potential issues researchers and medical experts have long sought to better understand.

“The spine is full of challenges and it’s a hard problem to solve,” Yakacki said. “People have tried making synthetic spinal tissue discs and they haven’t done a good job of it. With 3D printing, and the high resolution we’ve gotten from it, you can match a person’s anatomy exactly. One day, we may be able to grow cells to fix the spine, but for now, we can take a step forward with the next generation of materials. That’s where we’d like to go.”

This new biological tissue substitute could be used in myriad other and perhaps less obvious ways as well. One potential use for the material could be to create shock absorbing implants for our toes — potentially to help protect them from being stubbed during unfortunate run-ins with errant coffee tables.

Regardless of its applications, researchers are optimistic that the manner in which we look at and practice biological tissue mimicry will be fundamentally altered by this groundbreaking advancement.

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