New use for graphene in detecting brain disorders
doi:10.1038/nindia.2018.171 Published online 13 December 2018
Graphene, the super-strong ultra-light wonder material, may now find use in detecting brain disorders such as Amyotrophic Lateral Sclerosis (ALS)1.
Chemical engineer Vikas Berry and his team at University of Illinois in Chicago (UIC) reportthis potential new application of graphene, traditionally used to make flexible electronic components, enhances solar cell capacity, and in batteries.
Berry, an alumnus of Indian Institute of Technology Delhi, says the new application of graphene is via an ultra-sensitive platform that can efficaciously differentiate neurodegenerative diseases from one another and pinpoint a particular disease.
ALS, characterised by rapid loss of motor neurons controlling skeletal muscles, is a progressive brain disorder for which there is currently no objective diagnostic test.
Graphene consists of a single layer of carbon atoms arranged in a hexagonal lattice. Each atom binds to its neighbours through chemical bonds. The elasticity of these bonds produces resonant vibrations, known as phonons. The scientists exploited this ultra-sensitive property of graphene to detect ALS.
The resonant vibrations change in a very specific and quantifiable way when a foreign molecule is introduced into the lattice. The foreign molecule affects graphene’s vibrational energies, which can be accurately mapped using Raman spectroscopy.
For their experiments, the researchers used cerebro-spinal fluid (CSF) – found in the brain and spinal cord – from 13 people with ALS; three with multiple sclerosis (MS) and three with an unknown neurodegenerative disease. When they added the CSF from ALS patients, the scientists found a distinct change in the vibrational characteristics of graphene.
"The changes in graphene's phonon vibration-energies – as measured by Raman spectroscopy – were unique and distinct," Berry’s PhD student and co-first author Bijentimala Keisham told Nature India. "These distinct changes accurately predicted what kind of patient the CSF came from – one with ALS, MS or no neurodegenerative disease." The exact cause of these differences was, however, beyond the scope of their study.
The scientists, however, specified that this strategy does not analyse the Raman signal of the CSF but rather "looks at the change in the Raman signal from interfaced graphene."
The results, they say, suggests that this graphene platform can not only be used to potentially diagnose ALS, but also to monitor its progression. In the future, it could also help study the efficacy of therapeutics, Keisham said.
Material scientist Sabyasachi Sarkar from the Indian Institute of Engineering Science and Technology, Shibpur, West Bengal said though it is a good attempt to monitor ALS, reproducibility in designing such sensitive spectral probes for medical diagnostics does remain a challenge. "The 2D graphene peak position is sensitive to the number of layers present in the deposited graphene," he told Nature India.
1. Keisham, B. et al. Quantum capacitance based amplified graphene phononics for studying neurodegenerative diseases. ACS Appl. Mater. Interfaces. (2018) doi: 10.1021/acsami.8b15893