Researchers from Tufts University have demonstrated an electronic implant - composed of silk and magnesium - that eliminated bacterial infection in mice by delivering heat to infected tissue when triggered by a remote wireless signal.

The silk and magnesium then harmlessly dissolved in the test animals.
"This is an important step forward for the development of on-demand medical devices that can be turned on remotely to perform a therapeutic function in a patient and then safely disappear after their use, requiring no retrieval," said Fiorenzo Omenetto, senior author and professor of biomedical engineering at the Tufts University's School of Engineering in the US.

These wireless strategies could help manage post-surgical infection or pave the way for eventual 'wi-fi' drug delivery, he added.

In lab settings, devices were implanted in vivo (within the living) in S. aureus bacteria-infected tissue and activated by a wireless transmitter for two sets of 10-minute heat treatments.

Tissue collected from the mice 24 hours after treatment showed no sign of infection and surrounding tissues were found to be normal.

Devices completely dissolved after 15 days, and magnesium levels at the implant site and surrounding areas were comparable to levels typically found in the body, the authors observed.

The researchers also conducted in vitro (lab) experiments in which similar remotely controlled devices released the antibiotic ampicillin to kill E. coli and S. aureus bacteria.
The wireless activation of the devices was found to enhance antibiotic release without reducing antibiotic activity.

"The new wireless therapy devices are robust enough to survive mechanical handling during surgery but designed to harmlessly dissolve within minutes or weeks depending on how the silk protein was processed," added the paper's first author Hu Tao.

The research was published online in the journal Proceedings of the National Academy of Sciences.