The device is basically a single-layer organic nanometer-scale transistor on a glass slide. It contains the reduced form of the peptide glutathione (GSH), which reacts in a specific way when it comes into contact with the enzyme glutathione S-transferase (GST), linked to Parkinson’s, Alzheimer’s and breast cancer, among other diseases. The GSH-GST reaction is detected by the transistor, which can be used for diagnostic purposes.
The biosensor was developed as part of a FAPESP-funded Thematic Project entitled “Development of novel strategic materials for integrated analytical devices”. The project focuses on the development of point-of-care devices by researchers in a range of knowledge areas, using functional materials to produce simple sensors and microfluidic 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,” explained Carlos Cesar Bof Bufon, Head of LNNano’s Functional Devices & Systems Lab (DSF) and a member of the research team for the project, whose principal investigator is Lauro Kubota, a professor at the University of Campinas’s Chemistry Institute (IQ-UNICAMP).
In addition to portability and low cost, the advantages of the nanometric biosensor include its sensitivity in detecting molecules, according to Bufon.
“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,” he explained. "The device can detect such molecules even when they’re present at very low levels in the examined material, thanks to its nanometric sensitivity.” A nanometer (nm) is one billionth of a meter (10-9 meter), or one millionth of a millimeter.
The system can be adapted to detect other substances, such as molecules linked to different diseases and elements present in contaminated material, among other applications. This requires replacing the molecules in the sensor with others that react with the chemicals targeted by the test, which are known as analytes.
“LNNano’s Functional Devices & Systems division has developed several platforms for chemical, physical and biological sensing in areas of strategic importance both at home and abroad, such as health, environment and energy,” Bufon said.
The goal is “to have a series of solutions in the shape of point-of-care devices to respond with agility to a wide array of requirements”, he added. These include outbreaks of disease or the need to detect contaminants such as lead and toxins in water samples.