A team of researchers at the Korea Institute of Science and Technology (KIST) said they developed a biosensor that can distinguish small molecular neurotransmitters from body fluids like cerebrospinal fluids.

Recently, excessive stress and increased life expectancy have caused an increase in mental diseases such as schizophrenia, depression, insomnia, panic disorder, and dementia. 

However, mental illness still largely depends on medical diagnoses based on patient behavior and judgment but this prevents diagnosis if symptoms are not visibly expressed. MRI, CT, and PET tests performed for precise diagnosis are expensive and subjective judgments by doctors are involved in analyzing the images.

Accordingly, the research team decided to use the imbalance of neurotransmitters in body fluids as an indicator for diagnosing mental illness. 

Most neurotransmitters have very small molecular weights and similar chemical structures, requiring expensive large equipment and professionals to distinguish them.

The research team used a type of coordination polymer, a porous material, connected to a conductive metal-organic framework (MOF) which is capable of selectively adsorbing neurotransmitters and generating a characteristic electrical signal. It was manufactured in the form of a film and applied to field-type electrical signal sensors.

As each neurotransmitter has a different degree of adsorption to MOF depending on its size, charge strength, and chemical bond affinity, biosensors could be made to create a unique pattern of electrical signals depending on the type and amount of neurotransmitter, explained the researchers.

This biosensor accurately distinguishes several types of neurotransmitters with similar chemical structures and enables high-sensitivity quantitative detection, KIST said. 

For example, serotonin is observed at low concentrations in depressed patients and dopamine in Parkinson's disease patients, and this system can be used to measure the imbalance of several different neurotransmitters at once.

"The developed technology has the advantage of being able to diagnose mental illness early based on the quantitative analysis results of neurotransmitters,” said the research team. “It can be expanded to clinical brokerage research and developed to screen subjects that require additional detailed examinations such as MRI and CT."

The study was recently published in the Chemical Engineering Journal.