Three-dimensional printers are opening up new worlds to research.
Early adopters are using the technology to investigate complex molecules, fashion custom lab tools, share rare artefacts and even print cardiac tissue that beats like a heart. At palaeontology and anthropology conferences, more and more people are carrying printouts of their favourite fossils or bones. “Anyone who thinks of themselves as an anthropologist needs the right computer graphics and a 3D printer. Otherwise it’s like being a geneticist without a sequencer,” says Zollikofer.
Chemists and molecular biologists have long used models to get a feel for molecular structures and make sense of X-ray and crystallography data. Just look at James Watson and Francis Crick, who in 1953 made their seminal discovery of DNA’s structure with the help of a rickety construction of balls and sticks.
These days, 3D printing is being used to mock up far more complex systems, says Arthur Olson, who founded the molecular graphics lab at the Scripps Research Institute in La Jolla, California, 30 years ago. These include molecular environments made up of thousands of interacting proteins, which would be onerous-to-impossible to make any other way. With 3D printers, Olson says, “anybody can make a custom model”. But not everybody does: many researchers lack easy access to a printer, aren’t aware of the option or can’t afford the printouts (which can cost $100 or more).
The cellular matrix
Printer ‘inks’ aren’t limited to plastic. Biologists have been experimenting with printing human cells — either individually or in multi-cell blobs — that fuse together naturally. These techniques have successfully produced blood vessels and beating heart tissue. The ultimate dream of printing out working organs is still a long way off — if it proves possible at all. But in the short term, researchers see potential for printing out 3D cell structures far more life-like than the typical flat ones that grow in a Petri dish.
For example, Organovo, a company based in San Diego, California, has developed a printer to build 3D tissue structures that could be used to test pharmaceuticals. The most advanced model it has created so far is for fibrosis: an excess of hard fibrous tissue and scarring that arises from interactions between an organ’s internal cells and its outer layer. The company’s next step will be to test drugs on this system. “It might be the case that 3D printing isn’t the only way to do this, but it’s a good way,” says Keith Murphy, a chemical engineer and chief executive of Organovo.
In the meantime, basic plastic 3D printers are starting to allow researchers to knock out customized tools. Leroy Cronin, a chemist at the University of Glasgow, UK, grabbed headlines this year with his invention of ‘reactionware’ — printed plastic vessels for small-scale chemistry (M. D. Symes et al. Nature Chem. 4,349–354; 2012). Cronin replaced the ‘inks’ in a $2,000 commercially available printer with silicone-based shower sealant, a catalyst and reactants, so that entire reaction set-ups could be printed out. The point, he says, is to make customizable chemistry widely accessible. His paper showed how reactionware might be harnessed to produce new chemicals or to make tiny amounts of specific pharmaceuticals on demand. For now, other chemists see the idea as a clever gimmick, and are waiting to see what applications will follow.
The Scripps group uses a Z Corporation Spectrum Z510 printer which builds up objects by dragging a thin layer of plaster-of-paris powder over the entire canvas and depositing coloured glue in the appropriate spots for each layer.
Research labs use many types of 3D printers to construct everything from fossil replicas to tissues of beating heart cells. Arthur Olson’s team at the Scripps Research Institute in La Jolla, California, produces models of molecules; some are shown here partway through the printing process.
After the objects are finished, they must be separated from the loose powder with brushes and jets of air.