A $450 printer in Anne S. Meyer’s lab can build living structures more than 100 layers tall—far beyond the limits of earlier do-it-yourself bioprinters. The machine started as an ordinary plastic 3D printer, but its new job is to shape materials containing living cells.
These materials are a little like living tissue, with a key difference: researchers choose which cells go inside and what shape the finished material takes. Depending on the bacteria used, a printed structure might help clean contaminated water or break down waste such as plastic. But specialized bioprinters can cost more than $100,000, and the soft shapes they make may slump before they harden. That puts the technology out of reach for many labs.
Meyer, a professor of biology at the University of Rochester, has spent more than a decade building low-cost bioprinters in her lab. For this version, researchers from Rochester and Cornell University removed the plastic-filament part of a standard printer and fitted it with a syringe pump. The pump presses out “bio-ink,” a mix of living cells and a polymer solution that hardens into a gel.
The syringe can both push out and pull back the ink, helping prevent it from oozing at the edges. The team also developed a support gel, called a slurry, for the printer to deposit the bio-ink into. The slurry holds each shape in place and helps it set quickly, even when the structure is tall.
The modified printer can make more than 100 layers, compared with fewer than 20 layers for previous do-it-yourself models. It can also create hollow spaces inside its prints. Taller, more complex shapes can give bacteria a larger surface area relative to their volume. That may help the cells take in signals and nutrients from their surroundings and release useful products more quickly.
The researchers made two kinds of slurry. One makes it easier to remove a finished print. The other lets microbes remain alive while the printed material is incubated inside it. In tests described by the researchers, bacteria in this incubation slurry stayed alive for four weeks or more. In earlier methods, printed bacteria began dying after about nine days.
That extra time could help scientists study biofilms: communities of microorganisms, including bacteria, that stick to surfaces. Biofilms can cause problems, but they can also be useful. Researchers may be able to make living materials that better resemble biofilms found in medical settings, or that are mechanically stronger for practical uses.
The work, published in ACS Applied Polymer Materials, offers other labs a more affordable way to explore those possibilities. Meyer’s team built the printer for about $450 using readily available parts, and instructions are available on GitHub. The researchers’ next opportunity is to put the flexible tool to work on the many questions raised by living materials, from how microbes behave in complex shapes to what useful jobs engineered communities can perform.