Scientists are exploring ways to diagnose diseases by sniffing chemical compounds from bodily emissions such as breath, sweat, and tears.
These techniques are referred to as volatolomics and require multidisciplinary actors' collaborative efforts such as chemists, materials scientists, and electrical engineers, according to a review paper that was recently published in the journal Nano Research.
“There is a consensus between eastern and western traditional diagnosis of methodologies that smelling the breath from the upper [respiratory] tract is an effective way for clarifying health conditions both in Hippocrates’s Book of Prognostic written in 400 BC and Bian Que’s book of “The Yellow Emperor’s Canon of 81 Difficult Issues” written in ca. 200 BC,” the authors of the study write.
Volatile organic compounds [VOCs] found in scents and aromas have a high vapour pressure and low water solubility. They are emitted as gases from certain solids or liquids.
All organisms deliberately release VOCs for various purposes including defence, communication, and reproduction. But VOCs are also released incidentally as part of all biological processes, including processes related to illness.
“In the past 50 years, thousands of volatile biomarkers, ie, VOCs, associated with various diseases or lesions, have been identified and classified from multi-body sources.
“It boosts the development of this new era, volatolomics, such as human exhalation, skin emanations, urine headspace, blood, and faeces, towards good-efficient, high-accuracy non-invasive, and painless disease diagnosis/screening.”
Each VOC released from an organism contains a unique pattern of a disease. That is to say, there is a specific VOC “signature” or “fingerprint” for every condition.
If researchers and clinicians can catalogue the VOC fingerprint of different diseases, and engineers then develop devices that could quickly pinpoint a match to these fingerprints, this could create a groundbreaking development in diagnostics and treatment.
“Chemical analysis (detection and monitoring) of compounds associated with the metabolic activities of an organism is at the cutting edge of science. Volatile metabolomics (volatolomics) are applied in a broad range of applications, including: biomedical research, toxicological analysis, molecular communications, forensics, safety and security,” an earlier study explains.
Moreover, VOC diagnostics, relying on ‘sniffing’, is a non-invasive and painless procedure, unlike numerous existing diagnostic techniques.
There have been mentions of the possibilities offered via volatolomics during the height of the coronavirus pandemic, where dogs were taught to recognise the smell of SARS-CoV-2.
Still very new
Technological advances will make volatolomics feasible in the near future, be they in data mining, machine learning or nanomaterial sensors.
“But the field is so young, and draws in researchers from many fields such as chemistry, electrical engineering, computer science, materials science, and of course clinicians who deal with patients every day, who are unused to speaking to each other, who typically employ different methodologies, and who often do not even use the same terms,” said Yun Qian, a co-author of the review and researcher with the Cancer Center of Zhejiang University.
“So we brought a bunch of us from these various disciplines together to write a comprehensive review paper that we hope will work as a bridge connecting each other’s expertise in this sprawling field.”
A comprehensive new study of this very young field attempts to bridge the gap between the various disciplines involved.
To make the collaboration easier on the stakeholders, the authors listed all the VOCs associated with different diseases from all possible bodily sources in a reference manual of illness volatiles.
“This part of the review was crucial, as such a list of targets has been highly sought after by the chemists, materials scientists, and electrical engineers in particular,” added Mingshui Yao, another of the authors and researcher at the State Key Laboratory of Multi-phase Complex Systems with the Chinese Academy of Sciences.
“They needed to know what the fingerprints or ‘biomarkers’ are that they are designing their diagnostic equipment for. Now they can just look this up.”
Moreover, the review supplies a commentary on the technologies involved with volatolomics analysis, especially the “electronic nose” (E-nose) and “photonic nose” (P-nose), advanced devices used for VOC detection.
The researchers believe their review paper “well answers the question of how to connect the clinic, volatolomics, and sensing technology together.”
They then attempt to further clarify “the relationship between the volatolomics (bio- /chemical markers) and special disease needs” in the Conclusions and future perspectives section – for diagnoses based on volatolomics to be accepted as one of the standard diagnostics methods/techniques of specific diseases.
The authors hope volatolomics could be used as the go-to standard in clinical diagnostics in the future.