Although it appears to be the pinnacle of bling, a new technique for tattooing gold onto living tissue represents a step toward combining human cells with electronic gadgets.
Scientists etched patterns of gold nanodots and nanowires on living mouse embryo fibroblast cells using a fabrication process called nanoimprint lithography. They claim that this is a critical first step in incorporating more complicated circuits.
It isn’t only because cyborgs are cool. The technology could have amazing health applications, according to the experts who created it, led by engineer David Gracias of Johns Hopkins University.
“If you imagine where this is all going in the future, we would like to have sensors that can remotely monitor and control the state of individual cells and the environment surrounding those cells in real-time,” Gracias explains.
“If we had technologies to track the health of isolated cells, we might be able to diagnose and treat diseases much sooner, rather than waiting until the entire organ is damaged.”
Engineers have been attempting to merge electronics with human biology for some time, but there are substantial obstacles. One of the most significant challenges is the incompatibility of live tissue with the manufacturing techniques used to build electronics.
Although there are methods for making objects small and flexible, they frequently involve the use of harsh chemicals, high temperatures, or vacuums that damage living tissue or soft, water-based materials.
Gracias and his colleagues developed their technology on the basis of nanoimprint lithography, which is exactly what it sounds like using a stamp to imprint microscopic patterns into a material. The material is gold in this case, but that is only the first step in the process. After the pattern is created, it must be transferred and adhered to living tissue.
The researchers first printed their nanoscale gold onto a polymer-coated silicon wafer. The polymer was then dissolved, allowing the pattern to be transferred to thin glass films, which were then treated with a biological chemical called cysteamine and covered with a hydrogel.
The design was then removed from the glass and gelatin-treated before being transferred to a fibroblast cell. The hydrogel was finally dissolved. The cysteamine and gelatin assisted in bonding the gold to the cell, where it remained and migrated with the cell for the next 16 hours.
The researchers utilized the same method to attach gold nanowire arrays to ex vivo rat brains. The fibroblasts, though, are said to be the most interesting result.
“We’ve demonstrated that we can attach complex nanopatterns to living cells while keeping the cell alive,” Gracias explains.
“It’s a very important result that the cells can live and move with the tattoos because there’s often a significant incompatibility between living cells and the methods engineers use to fabricate electronics.”
Because nanoscale lithography is simple and inexpensive, the work represents a step toward developing more complex electronics such as electrodes, antennas, and circuits that can be integrated not only with living tissues, but also with hydrogels and other soft materials that are incompatible with harsher fabrication methods.
“We expect this nanopatterning process, when combined with various classes of materials and standard microfabrication techniques like photolithography and e-beam lithography,” the researchers write, “to open up opportunities for the development of new cell culture substrates, biohybrid materials, bionic devices, and biosensors.”
