Sep 3, 2015 | By Alec

While lives are already being saved by quality 3D printing in academic hospitals all over the world, most of these cases involve 3D printed implants and replicas used to prepare for unusual surgeries. Doubtlessly, the real 3D printing revolution in the medical world is yet to come: bio 3D printing. Involving special bio-inks made from biocompatible polymers and cells, these could be used for 3D printing just about everything in the human body. And while most existing bio-inks are very limited in their usage, a team of scientists from Tufts University has now developed a silk-based bio-ink that is far more flexible and use and can even be 3D printed at room temperature.

For while the concept of bio-inks sounds fantastic – after all, 3D printing cartilage, blood vessels and even entire organs truly saves lives – the truth is that current bio-inks just aren’t very potent yet. Most of these inks with express 3D printing purposes in mind are made from a variety of materials, including thermoplastics, silicones, collagen, gelatin or alginate. While all have different properties, they share a few negative characteristics. For example, all are highly vulnerable and fluctuating temperatures, changes in pH values and even crosslinking methods – which are all crucial in their use – can also damage the cell structures that are 3D printed. This means that other materials need to be added to improve the bio-inks, and some have been successful with a number of additives, including cytokines and antibiotics, which can be useful to control cell functions or deal with infection dangers.

However, it is obvious that none of those options are really perfect, as what we need is a bio-ink capable of withstanding or not even needing fluctuating temperatures, changes in pH values and crosslinking methods. This has seriously stalled the advance of 3D bioprinting research. But now, finally, it looks like the solution has been discovered. To address the limitations of bio-inks, professor David L. Kaplan, professor of engineering at Tufts University, and his team turned to silk proteins.

With it, they developed a bio-ink that doesn’t even require these harsh processing conditions, but that can instead be simply 3D printed at room temperature. As they explain in a paper published in the journal ACS Biomaterials Science & Engineering, they created it by combining silk proteins (which are biocompatible) with glycerol, a non-toxic sugar alcohol very commonly used by the pharmaceutical industry.

This created a biocompatible ink that was clear, self-curing, flexible and very suitable for a number of laboratory applications. It was even very stable in water, so very versatile. Most importantly, ‘[it avoids] the need for chemical or photo initiators,’ they write.

The research team behind this silk-based ink very optimistic, and have stated that it could be used in a variety of biomedical applications. As part of their research, they developed inks for specific 2D and 3D printing applications. ‘By varying the formulations the crystallinity of the silk polymer matrix could be controlled to support printing in 2D and 3D formats interfaced with CAD geometry and with good feature resolution,’ they write. Furthermore, the self-curing characteristic of this ink was optimized to enable to formation of structural and support materials during printing.

The hope is that these ‘biocompatible aqueous protein inks’ can now start a new wave of bioprinted innovation. Perhaps we won’t have to wait years before seeing some actually applicable medical results after all.



Posted in 3D Printing Materials



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