Researchers from the University of Pennsylvania have succeeded in developing a nanotechnological device that combines carbon nanotubes and proteins that are olfactory receptors, the same components in the nose responsible for sensing smells.
Given the fact that olfactory receptors belong to a larger family of proteins involved in signals transmitted through the cell membrane, these devices could have applications beyond smell sensing, such as pharmacological research. The research findings were published in the scientific journal DHW Nano.
The research team from the University of Pennsylvania worked with olfactory receptors derived from mice, although all olfactory receptors are part of a family of proteins known as G Protein Coupled Receptors or GPCRs. These receptors are located on the outer side of the cell membrane, where various chemicals in their environment are able to bind to them. The binding action is the first step in a chain of chemical reactions leading to a cellular reaction; In the case of the olfactory receptor, this chain leads to the activation of the sense of smell.
The researchers were able to build an interface between this complex protein and a carbon nanotube transistor, allowing them to convert the chemical signals that the receptor normally produces into electrical signals capable of operating other systems and devices.
"Our nanotechnology devices are reading systems; they eavesdrop on what the odor receptors are doing, especially the molecules that bind to them," explains the researcher. Since the proteins the researchers used were odor receptors, the test for the activity of their nanotube device was its function as a sensor for airborne chemicals. "If there is something in the atmosphere that can bind to this molecule, what we get from the nano-tube is an indication of whether there is binding or not. That is, we can get a continuous reading indicating the concentration of the molecule in the air," explains the researcher.
Although it is possible to imagine a collection of such nanotube devices that together form a synthetic nose - each of which corresponds to about three hundred and fifty of the olfactory receptors in a human nose, or the thousand found in a dog's nose - the researchers believe that medical applications are much closer to reality than we think.
"These proteins are common targets for drugs," explains the researcher. "Since it is known that they are very important in cell-environment interactions, they are also very important in relation to the pathology of diseases. In this regard, we now have a tool that allows us to study the exact activity of these proteins. We can imagine the construction of a chip containing many devices of the type This, when each of them contains a different protein, and exposing them simultaneously to different drugs in order to examine which of them is effective in triggering a response."
Revealing the types of drugs that bind best to these proteins is also important since disease-causing agents usually attack these receptors. The better a harmless chemical binds to a specific protein, the better it is an inhibitor of the disease involving that protein. The team of researchers was also able to make technical progress in stabilizing proteins of this type for the benefit of future research.
"In the past, if you took a protein out of the cell and put it into the device, it could survive for up to one day. However, here, we were able to anchor it to a nanoscale artificial cell membrane known as a nanoplate," the researcher points out. "When we did that, the proteins survived for two and a half months instead of one day."
Extending the life span of such devices could be valuable in two scientific fields that are close, and sometimes even overlap - nanotechnology and biology," explains the researcher. "These complex molecular machines are the main method of communication between the inside of the cell and the environment outside it, and now we are examining their functionality with the help of Our nanotechnological devices."
