(Inside Science) -- Traditional 3-D printing with materials like plastic or metal has already broken the mold in manufacturing. Now researchers are taking the versatility of this technology one step further. Scientists from the Massachusetts Institute of Technology have 3-D printed structures filled with living, genetically engineered bacteria. The team envisions that the innovation could help researchers develop biomedical devices such as implants programed to monitor inflammation and release growth factors to promote blood vessel formation, or ingestible devices that could modify the gut microbiota to treat conditions such as obesity.
The bacteria-filled ink used to make the 3-D structures can respond to the environment by secreting chemicals or fluorescent proteins. The team harnessed this trait to design living logic gates, as well as a “living tattoo” that sticks to the skin and lights up in the presence of certain chemicals.
Living inks present their own set of challenges: While bacteria are hardier than mammalian cells, they can still starve or dry out. The MIT researchers designed an ink that, when set, supports the cells in a polymer-based matrix that can hold a large amount of water. The bacteria are sustained by a nutrient broth also contained in the ink.
While this is not the first living ink, the researchers emphasize that their use of genetically programmed cells makes it particularly versatile. The team also experimented with the composition of the ink and the printing pressure until they found a combination of settings that allowed the ink to flow without clogging, but prevented it from spreading too much once it was out of the nozzle. They were able to print 3-centimeter-wide structures with fine details down to the width of a human hair.
The researchers published their results last week in the journal Advanced Materials.