New biodegradable implants can be activated wirelessly to deliver therapy and dissolve harmlessly once they finish their job, researchers say.
A drawback of implantable medical devices such as pacemakers is how many eventually need further surgery to remove them once they no longer are useful. To avoid disrupting healthy tissue and risking post-surgery complications such as infection, scientists have now designed and tested a device the size of a postage stamp that degrades safely inside the body, eliminating the need for follow-up surgery.
The invention consists of a magnesium heating coil just 200 nanometers or billionths of a meter thick, thinner than a wavelength of visible light. This flat coil is sandwiched between layers of silk protein from silkworms, for a device less than 100 microns thick, the average width of a human hair. “The device is encased in a biological version of Ziploc,” says study co-author Fiorenzo Omenetto, a biomedical engineer at Tufts University in Medford, Mass.
The researchers implanted their gadget in mice infected with Staphylococcus aureus bacteria and powered it wirelessly via magnetic induction, heating the skin of the rodents, lowering bacterial levels and speeding wound healing. After 15 days, the remote-controlled device had dissolved without a trace. The scientists also developed an enhanced version of their implant where the silk released an antibiotic when heated.
Omenetto and his colleagues suggest they can control how long the implants last by tweaking how thick or crystalline the silk fibers are. “We’d like them to last longer than days or weeks,” Omenetto says. Future research can also add more functions to the devices, he adds.
The scientists detailed their findings online Nov. 24 in the journal Proceedings of the National Academy of Sciences.
