An electronic device made of egg protein albumin has been created by Chinese researchers, paving the way for dissolvable sensors that could be used inside the human body.
The device - known as the memristor, or memory resistor - is used to regulate the flow of electric current and can also remember charges. It has magnesium and tungsten-based electrodes that are incorporated on a thin film of albumin, a protein found in egg whites.
In tests, the memristor performed as well as a standard non-biodegradable device. When used in dry laboratory conditions, the device’s performance remained consistent for more than three months. In water, however, it dissolved almost completely within three days.
The ability to dissolve without trace shows promise for possible medical applications. The researchers envision dissolvable sensors or drug-delivery devices that could be injected into the body, do their job and then harmlessly dissolve without having any negative effects on the person’s health.
The egg-based memristor was developed by researchers from the Zhejiang University in China and presented in an article in the journal Applied Materials and Interfaces. However, other teams have experimented with different materials to produce dissolvable electronics including DNA, other types of proteins and metals.
In an article published in the journal Nano Letters this week, a team from the University of Montreal described a DNA-based thermometer, which they claimed was the smallest ever created. 20,000 times thinner than a human hair, the thermometer could allow researchers in future to measure temperature on the level of individual cells.
"DNA is made from four different monomer molecules called nucleotides: nucleotide A binds weakly to nucleotide T, whereas nucleotide C binds strongly to nucleotide G," explained David Gareau, first author of the study. "Using these simple design rules we are able to create DNA structures that fold and unfold at a specifically desired temperature.”
The ability of DNA molecules to unfold when heated was described already 60 years ago. It has also been known that some RNA molecules function as nanothermometers inside living organisms. The Montreal University team essentially recreated this natural function of DNA and RNA molecules.
"In the near future, we also envision that these DNA-based nanothermometers may be implemented in electronic-based devices in order to monitor local temperature variation at the nanoscale," said Professor Alexis Vallée-Bélisle.
"There are still many unanswered questions in biology. For example, we know that the temperature inside the human body is maintained at 37° C, but we have no idea whether there is a large temperature variation at the nanoscale inside each individual cell."