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Scientists Develop Novel Biosensor Made of Electron-Accepting Polymer

A low-cost sensor made from semiconducting plastic could be used to diagnose or monitor a wide range of health conditions, such as surgical complications or neurodegenerative diseases. Image credit: KAUST.

A low-cost sensor produced with semiconducting plastic and could be used to monitor or diagnose a broad range of health conditions, such as neurodegenerative diseases or surgical complications, has been developed by an international group of scientists.

The sensor has the ability to measure the amount of critical metabolites, such as glucose or lactate, contained in saliva, sweat, blood, or tears. Furthermore, upon being integrated into a diagnostic device, it helps achieve low-cost, rapid, and accurate monitoring of health conditions.

The design of the innovative device is far simpler compared to that of prevalent sensors, and it opens the door for a wider array of new prospects for health monitoring down to the cellular level. The outcomes of the study have been reported in the Science Advances journal.

A group headed by the University of Cambridge and King Abdullah University of Science and Technology (KAUST) in Saudi Arabia developed the device.

Semiconducting plastics such as those employed in this study are being produced for being applied in flexible electronics and solar cells; however, they have not yet been widely used for biological applications.

In our work, we’ve overcome many of the limitations of conventional electrochemical biosensors that incorporate enzymes as the sensing material.

In conventional biosensors, the communication between the sensor’s electrode and the sensing material is not very efficient, so it’s been necessary to add molecular wires to facilitate and ‘boost’ the signal.”

Dr Anna-Maria Pappa, Lead Author

The sensor was built by Pappa and her team using a newly synthesized polymer developed at Imperial College that functions like a molecular wire, which directly accepts the electrons generated at the time of electrochemical reactions.

Upon coming into contact with a liquid such as tears, sweat, or blood, the material absorbs ions and expands, eventually getting merged with the liquid. The result is considerably higher sensitivity than conventional sensors formed of metal electrodes.

Furthermore, upon integrating the sensors into more complex circuits, such as transistors, it would be possible to amplify the signal and respond to minute fluctuations in metabolite concentration, in spite of the very small size of the devices.

During the initial investigations of the sensors, levels of lactate were measured, which is helpful in fitness applications or to monitor patients after a surgery.

Yet, the researchers stated that it is possible to modify the sensor to detect other metabolites, such as cholesterol or glucose, by incorporating the suitable enzyme, and it would be possible to adjust the concentration range that can be detected by the sensor by altering the geometry of the device.

This is the first time that it’s been possible to use an electron accepting polymer that can be tailored to improve communication with the enzymes, which allows for the direct detection of a metabolite: this hasn’t been straightforward until now.

It opens up new directions in biosensing, where materials can be designed to interact with a specific metabolite, resulting in far more sensitive and selective sensors.”

Dr Anna-Maria Pappa, Lead Author

Due to the fact that the sensor does not include metals such as platinum or gold, it can be produced at a lower cost and can be easily integrated into stretchable and flexible substrates, opening the door for their use in implantable or wearable sensing applications.

At present, the aim of the team is to develop the sensor to monitor metabolic activity of human cells in real time outside the body.

The focus of the Bioelectronic Systems and Technologies group where Pappa is based is to develop models with the ability to closely simulate our organs, together with technologies with the potential to accurately evaluate them in real time. The toxicity or potency of drugs can be tested by using the developed sensor technology in tandem with these models.

The Marie Curie Foundation, the KAUST Office of Sponsored Research, and the Engineering and Physical Sciences Research Council funded the study.

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