Recently, researchers from MIT have combined sensor technology with carbon nanotubes. Carbon nanotubes are hollow, cylindrical, one-nanometer structures made of pure carbon.
Postdoc Nicole Iverson and Professor Michael Strano, of MIT, have created new carbon nanotube sensors by borrowing principles from numerous fields such as chemistry, nanomaterials, medicine, polymers, biology, and optics. These innovative sensors can be implanted into cancer patients for monitoring purposes.
Development of Carbon Nanotube Sensors
In the human body, Nitric Oxide (NO) acts as one of the crucial signaling molecules in living cells by carrying messages within the brain and coordinating the operations of the immune system.
MIT researchers believe that nitric oxide plays a significant role in cancer progression, which inspired the development of a tool to understand and study this phenomenon.
They modified the nanotubes to create two different types of sensors. One sensor is designed to be injected into the bloodstream for short-term monitoring, while the other is designed to be embedded in a gel, so it can be implanted long-term under the skin.
These sensors utilize the natural fluorescence of carbon nanotubes for monitoring. When the nanotubes are coupled to a molecule that is bound to a specific target, the fluorescence brightens or dims depending on the condition of cells.
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The Short-Term Sensor
After testing the sensor on mice, Iverson decided to attach PEG - a biocompatible polymer that can restrain particle clumping in the bloodstream - ensuring that the sensor could be safely injected. The testing on mice revealed that, when injected, the sensor flowed via the lungs and heart without causing any damage, and finally reached the liver, where it could be used to monitor nitric oxide, which is linked with inflammation.
The Longer-Term Sensor
The sensor comprises of nanotubes placed in a gel made from alginate (a polymer found in algae). The gel was tested on mice by placing the gel under the skin. The test revealed that the sensor stayed in place and was operational for 400 days.
With the sensor in place, the researchers used a near-infrared laser to shine on the area with the sensor, causing it to produce a near-infrared fluorescent signal that is read by an instrument designed to notify the difference between nanotubes and other background fluorescence.
According to the researchers, the length of time the sensor can be implanted is extendable. Apart from monitoring cancer and other inflammatory diseases, it can also be used for detecting immune reactions in patients with artificial hips or other implanted devices.
This experiment was the first time a Nano sensor was successfully used in the body of a mouse for an extended period.
The new sensors provide data in real time, thereby making them highly useful in the medical field to detect cancer cells. The researchers believe that soon these sensors can be developed further to include glucose detection in diabetic patients as well. This would mean that diabetic patients would no longer need to take daily blood samples.
A study in 2018 showed that dispersible electrodes based on gold-coated magnetic nanoparticles modified with DNA can detect microRNA in unprocessed blood samples at very low concentrations. This is the first of its kind and has been tested on mice models. The new device can get to work in just 30 minutes and can be used as a finger-prick test for early-stage cancer detection and diagnosis.
References and Further Reading
- MIT News. (2013). http://news.mit.edu/2013/new-implantable-sensor-paves-way-long-term-monitoring
- Iverson, N., Barone, P., Shandell, M., Trudel, L., Sen, S., Sen, F., Ivanov, V., Atolia, E., Farias, E., McNicholas, T., Reuel, N., Parry, N., Wogan, G., Strano, M. (2013). In vivo biosensing via tissue-localizable near-infrared-fluorescent single-walled carbon nanotubes. Nature Nanotechnology. https://www.nature.com/articles/nnano.2013.222
This article was updated on the 1st August, 2019.