PREVIEW

Scientists have developed a 3D-printed band-aid for the heart inspired by the way worms interact in nature.

A team at the University of Colorado Boulder, in collaboration with researchers at the University of Pennsylvania, has innovated a new 3D printing method to create material that is elastic enough to endure a heart’s constant beating, robust enough to handle the stress on joints, and adaptable enough to fit a patient’s unique defects.

The resulting material could be used to repair leaky heart valves or stabilise spinal discs, among other applications.

Their breakthrough, detailed in the August 2 edition of the journal Science, paves the way for a new generation of biomaterials. The materials range from internal bandages that deliver drugs directly to the heart to cartilage patches and needle-free sutures.

“Cardiac and cartilage tissues are similar in that they have very limited capacity to repair themselves. When they’re damaged, there is no turning back,” said senior author Jason Burdick, a professor of chemical and biological engineering at CU Boulder’s BioFrontiers Institute. “By developing new, more resilient materials to enhance that repair process, we can have a big impact on patients.”

Traditionally, biomedical devices have been manufactured using moulding or casting, techniques suitable for the mass production of identical implants but impractical for personalising implants for specific patients. Recently, 3D printing has unlocked new possibilities for medical applications by enabling researchers to create materials in various shapes and structures.

Unlike conventional printers that place ink on paper, 3D printers build objects by depositing layers of plastics, metals, or even living cells.

One promising material, known as hydrogel (used in contact lenses), has been a favoured candidate for fabricating artificial tissues, organs, and implants.

However, translating these from the lab to the clinic has been challenging because traditional 3D-printed hydrogels often break when stretched, crack under pressure, or are too stiff to mould around tissues.

“Imagine if you had a rigid plastic adhered to your heart. It wouldn’t deform as your heart beats,” said Burdick. “It would just fracture.”

To achieve both strength and elasticity in 3D-printed hydrogels, Burdick and his team drew inspiration from worms, which repeatedly tangle and untangle themselves in three-dimensional “worm blobs” that exhibit both solid and liquid-like properties. Previous research has shown that incorporating similarly intertwined chains of molecules, known as “entanglements,” can enhance toughness.

Their new printing method, called CLEAR (Continuous-curing after Light Exposure Aided by Redox initiation), involves a series of steps to entangle long molecules inside 3D-printed materials, mimicking those intertwined worms.

When the team tested the materials in the lab by stretching and loading them (one researcher even ran over a sample with her bike), they found them to be exponentially tougher than materials printed with a standard method known as Digital Light Processing (DLP). Moreover, these materials conformed and adhered to animal tissues and organs.

“We can now 3D print adhesive materials that are strong enough to mechanically support tissue,” said co-first author Matt Davidson, a research associate in the Burdick Lab. “We have never been able to do that before.”

Burdick envisions a future where such 3D-printed materials could repair heart defects, deliver tissue-regenerating drugs directly to organs or cartilage, stabilize bulging discs, or even be used for suturing in the operating room without causing tissue damage like traditional needles and sutures.

His lab has filed for a provisional patent and plans to conduct further studies to better understand how tissues interact with these materials.

However, the team stresses that their new method could have impacts far beyond medicine - in research and manufacturing, too. For instance, their method eliminates the need for additional energy to cure, or harden, parts, making the 3D printing process more environmentally friendly.

“This is a simple 3D processing method that people could ultimately use in their own academic labs as well as in industry to improve the mechanical properties of materials for a wide variety of applications,” said first author Abhishek Dhand, a researcher in the Burdick Lab and doctoral candidate in the Department of Bioengineering at the University of Pennsylvania. “It solves a big problem for 3D printing.”