MIT Media Lab

Hybrid living materials (HLMs)

source:newsmitedu

A method for printing 3D objects that can control living organisms in predictable ways has been developed by an interdisciplinary team of researchers at MIT and elsewhere. The technique may lead to 3D printing of biomedical tools, such as customized braces, that incorporate living cells to produce therapeutic compunds such as painkillers or topical treatments, the researchers say.

The new development was led by MIT Media Lab Associate Professor Neri Oxman and graduate students Rachel Soo Hoo Smith, Christoph Bader, and Sunanda Sharma, along with six others at MIT and at Harvard University’s Wyss Institute and Dana-Farber Cancer Institute. The system is described in a paper recently published in the journal Advanced Functional Materials.

“We call them hybrid living materials, or HLMs,” Smith says. For their initial proof-of-concept experiments, the team precisely incorporated various chemicals into the 3D printing process. These chemicals act as signals to activate certain responses in biologically engineered microbes, which are spray-coated onto the printed object. Once added, the microbes display specific colors or fluorescence in response to the chemical signals.

In their study, the team describes the appearance of these colored patterns in a variety of printed objects, which they say demonstrates the successful incorporation of the living cells into the surface of the 3D-printed material, and the cells’ activation in response to the selectively placed chemicals.

The objective is to make a robust design tool for producing objects and devices incorporating living biological elements, made in a way that is as predictable and scalable as other industrial manufacturing processes.

The team uses a multistep process to produce their hybrid living materials. First, they use a commercially available multimaterial inkjet-based 3D printer, and customized recipes for the combinations of resins and chemical signals used for printing. For example, they found that one type of resin, normally used just to produce a temporary support for overhanging parts of a printed structure and then dissolved away after printing, could produce useful results by being mixed in with the structural resin material. The parts of the structure that incorporate this support material become absorbent and are able to retain the chemical signals that control the behavior of the living organisms.

Finally, the living layer is added: a surface coating of hydrogel — a gelatinous material composed mostly of water but providing a stable and durable lattice structure — is infused with biologically engineered bacteria and spray-coated onto the object.

“We can define very specific shapes and distributions of the hybrid living materials and the biosynthesized products, whether they be colors or therapeutic agents, within the printed shapes,” Smith says. Some of these initial test shapes were made as silver-dollar-sized disks, and others in the form of colorful face masks, with the colors provided by the living bacteria within their structure. The colors take several hours to develop as the bacteria grow, and then remain stable once they are in place.

“There are exciting practical applications with this approach, since designers are now able to control and pattern the growth of living systems through a computational algorithm,” Oxman says. “Combining computational design, additive manufacturing, and synthetic biology, the HLM platform points toward the far-reaching impact these technologies may have across seemingly disparate fields, ‘enlivening’ design and the object space.”

The printing platform the team used allows the material properties of the printed object to be varied precisely and continuously between different parts of the structure, with some sections stiffer and others more flexible, and some more absorbent and others liquid-repellent. Such variations could be useful in the design of biomedical devices that can provide strength and support while also being soft and pliable to provide comfort in places where they are in contact with the body.

The team included specialists in biology, bioengineering, and computer science to come up with a system that yields predictable patterning of the biological behavior across the printed object, despite the effects of factors such as diffusion of chemicals through the material. Through computer modeling of these effects, the researchers produced software that they say offers levels of precision comparable to the computer-assisted design (CAD) systems used for traditional 3D printing systems.

The multiresin 3D printing platform can use anywhere from three to seven different resins with different properties, mixed in any proportions. In combination with synthetic biological engineering, this makes it possible to design objects with biological surfaces that can be programmed to respond in specific ways to particular stimuli such as light or temperature or chemical signals, in ways that are reproducible yet completely customizable, and that can be produced on demand, the researchers say.

“In the future, the pigments included in the masks can be replaced with useful chemical substances for human augmentation such as vitamins, antibodies or antimicrobial drugs,” Oxman says. “Imagine, for example, a wearable interface designed to guide ad-hoc antibiotic formation customized to fit the genetic makeup of its user. Or, consider smart packaging that can detect contamination, or environmentally responsive architectural skins that can respond and adapt — in real-time — to environmental cues.”

In their tests, the team used genetically modified E. coli bacteria, because these grow rapidly and are widely used and studied, but in principle other organisms could be used as well, the researchers say.

The team included Dominik Kolb, Tzu-Chieh Tang, Christopher Voigt, and Felix Moser at MIT; Ahmed Hosny at the Dana-Farber Cancer Institute of Harvard Medical School; and James Weaver at Harvard’s Wyss Institute. It was supported by the Robert Wood Johnson Foundation, Gettylab, the DARPA Engineered Living Materials agreement, and a National Security Science and Engineering Faculty Fellowship.
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source:architectmagazinecom

An interdisciplinary group led by MIT Media Lab associate professor and Mediated Matter research group director Neri Oxman has developed a new method of printing 3D objects with living biological organisms, such as bacteria, to produce hybrid living materials. These HLMs could be used to create biomedical tools, such as braces customized with living cells that then produce painkillers or topical treatments, the researchers tell MIT News. During their proof-of-concept experiments, the team printed objects that precisely incorporated chemicals that would activate a response in biologically engineered microbes. A layer of these living microbes were then spray-coated onto the printed object and displayed specific colors or fluorescence in areas treated with the integrated, 3D printed chemicals. The printing platform can also produce objects with user-specified variability in material properties, such as stiffness and absorption. For this study, Oxman’s team included graduate students Rachel Soo Hoo Smith, Christoph Bader, and Sunanda Sharma; Dominik Kolb, Tzu-Chieh Tang, Christopher Voigt, and Felix Moser at MIT; Ahmed Hosny at the Dana-Farber Cancer Institute of Harvard Medical School; and James Weaver at Harvard’s Wyss Institute.
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source:3dnativescom

Hybrid Living Materials (HLMs) are formed by combining living and non-living components such that the resulting composite takes on the properties of both. At MIT’s Media Lab Mediated Matter group, researchers have been studying how 3D printing technologies can control the behaviour of these hybrid materials. More precisely, they hope that controlling the behaviour of the live bacteria inside the HLMs could someday enable medical devices with therapeutic agents built in.

The new development was led by MIT Media Lab Associate Professor Neri Oxman and graduate students. During experiments, a layer containing living engineered bacteria was coated onto the object being 3D printed. Additionally, the team incorporated various chemicals into the 3D printing process, which acted as signals for the biologically engineered bacteria (the team used genetically modified E. coli bacteria). They were able to observe that the bacteria was responding to the chemicals as it changed colour and fluorescence in certain areas. They repeated this process a few times and noticed the appearance of colored patterns in a variety of 3D printed objects, realizing quickly that cells had successfully been incorporated into the surface of the 3D printed materials as they were responding to the chemicals!

Naturally, the team had to produce their HLMs. To do so, they invested in a commercially available multimaterial Binder Jetting 3D printer and customized combinations of resins and chemical signals which they used for 3D printing. Once they had the custom resin, they added the living layer, which consisted of a surface coating of hydrogel infused with biologically engineered bacteria. The living layer was spray-coated onto the object. Rachel Soo Hoo Smith, one of the graduate students working on the project explains: “We can define very specific shapes and distributions of the hybrid living materials and the biosynthesized products, whether they be colors or therapeutic agents, within the printed shapes.” Once sprayed the colours took a few hours to develop, the time for bacteria to grow.

These results point to very promising applications, especially for the medical sector. This printing platform allowed material properties to vary within the same object, with some sections stiffer and others flexible, some more absorbent and others liquid-repellent – the resulting variations could be very useful for medical devices! For example, the team explained that biomedical devices designed in this way could provide strength and support while also being soft and pliable to provide comfort in places where they are in contact with the body.