In a minimally invasive procedure, the international team of researchers inserted a wireless, biodegradable device into the deep brain region of a mouse. The device collected data on levels of dopamine and other properties of the brain, including pH levels, temperature and electrophysiology before dissolving back into the body.
Dopamine is critical in many neural-related conditions, so a biodegradable sensor to detect the neurotransmitter could be used by doctors for a range of treatments and operations.
“The direct measurement of dopamine can be very significant because of the role that neurotransmitters play in a lot of neural related disease,” said Penn State’s Larry Cheng, the Dorothy Quiggle Professor in Engineering and an associate of the Institute for Computational and Data Sciences. “I think people in the past have been looking at a lot of the other parameters in form of temperature, or fever, or sweating, among others. These related parameters can be very helpful when we don't have the direct measurement, but if we can have the direct measurement of this neurotransmitter at the target location, and in real time, that can be certainly more direct and even more helpful, because information can sometimes be very challenging to infer based on those other parameters.”
According to Penn State, the silicon-based implant includes two-dimensional transition metal dichalcogenides (TMDCs), an emerging class of materials increasingly used in nanoelectronics and nanophotonics applications. The ability for these atomically thin TMDCs to be manipulated allowed the scientists to design the implant to be biodegradable yet maintain electrical and electrochemical performance.
To make it implantable, the equipment is housed in probe measuring about 13 or 14mm long.
“That's really for the entire device, but, if we’re talking about the sensor, itself, that is even smaller,” Cheng said in a statement.
The team tested the device by inserting the probe into the basal ganglia section of the mouse’s brain.
In a clinical setting, Cheng said patients would wear a headband or other type of apparatus to relay the implant’s signals to equipment that medical staff could the use to monitor the patients’ condition.
According to the researchers, the main benefit of a biodegradable device is that it would require no further surgeries to remove the device.
“Currently, after full recovery, the device has to be removed, or there will be just something inside we don't need to use,” said Cheng. “So that's why here, the device is designed to be biodegradable and after a certain amount of time and after it has fulfilled its function, it can safely dissolve. So, the patient won't need to have go through the second surgery operation to remove the device.
The sheer number of chemicals, materials and designs that could be used to make this device required advanced computing techniques, said Cheng. He added that computers were used to simulate different chemicals and bioengineering schemes to find the ideal materials and design to detect and measure the target molecule.
“We have to introduce the material to model the 2D material and the dopamine and then you have to make sure they are stable,” said Cheng. “So, we'll have to optimise the initial structure and then we further study the interaction between the stabilised material and the dopamine.”
Future work could be aimed at creating a biodegradable sensor that monitors other aspects of brain chemistry, beyond dopamine detection, Cheng said.
The researchers reported on their findings in a recent issue of Advanced Materials.