Cancer and neurodegenerative diseases like Alzheimer's and Parkinson's are all able to be better treated if detected early. Unfortunately, this is not always the case as symptoms may not appear until these diseases are well established. To help counteract this problem, scientists at the National Nanotechnology Laboratory (LNNano) in Brazil have created a biosensor capable of rapidly detecting molecules specifically linked to various cancers and neurological diseases.
Essentially a nanometer-size, single-layer organic transistor mounted on a glass slide, the new biosensor contains a reduced form of a peptide (a short chain amino acids; also referred to as "small proteins") known as glutathione (GSH). This substance, when exposed to the enzyme glutathione S-transferase (GST) – associated with Parkinson's, Alzheimer's, breast cancer and a number of other diseases – creates a reaction that is detected by the transistor.
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"This is the first time organic transistor technology has been used in detecting the pair GSH-GST, which is important in diagnosing degenerative diseases, for example," said Carlos Cesar Bof Bufon, Head of LNNano's Functional Devices & Systems Lab (DSF). "The device can detect such molecules even when they're present at very low levels in the examined material, thanks to its nanometric sensitivity."
As part of a larger project focusing on the evolution of point-of-care devices for a range of specialized areas, LNNano researchers are developing functional materials to manufacture uncomplicated sensors and associated microfluidic (devices that incorporate biochemistry and nanotechnology to process low volumes of fluid) systems for rapid diagnosis.
"Platforms like this one can be deployed to diagnose complex diseases quickly, safely and relatively cheaply, using nanometer-scale systems to identify molecules of interest in the material analyzed," said Carlos Cesar Bof Bufon.
As well as being highly portable and cheap to make, the nanometric biosensor is also very sensitive in detecting specific molecules and could be adapted to sniff out other substances, for example particles associated with other forms of disease or contaminants in other materials. This can be readily achieved by replacing the detecting peptides in the sensor with others that react similarly with other substances examined.
The researchers are also attempting to reduce costs by developing paper-based, disposable biosensors. As paper is an insulator in its standard state, Bufon and his team have come up with a way to make paper conductive and able to transmit sensing data by inserting conductive polymers into the cellulose fibers of the paper.
Using a technique of gas-phase chemical polymerization, the paper acquires the conductive properties of the polymers and can be further improved by optimizing the element embedded in the paper for the chemical application it is designed to test. In this way, future iterations of the biometric sensor may be paper-based, semiconductive detectors able to interact with molecules across physical, chemical, and electrochemical ranges.
The research has been published in the journal Organic Electronics.