The new invention provides a convenient way for real-time detection of biomarkers in exhaled air.
While many diseases display no symptoms in the early stages, our immune systems will, nevertheless, defend our bodies from these unwanted invasions. By secreting early warning signals like blood, exhaled breath, sweat, tears, and urine, such signals can often be used as biomarkers to diagnose diseases early.
A new invention, involving the use of a smartphone, designed by Professor Jiang Changlong’s team from the Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, attained visual detection analysis for lung cancer and ketosis/diabetes via different testing probes.
The study, published in Analytical Chemistry, describes a portable smartphone platform that is based on a single-particle dual-emissions ratio fluorescent probe that can visualise detection of isopropanol in exhaled breath to provide early warning of lung cancer risk, and another fluorescent probe that can adequately capture acetone in the blood as well as exhaled breath to warn ketosis/diabetes.
With two high-efficiency organic ratio fluorescent nanoprobes, the team was able to utilise the colour recognisers of smartphones to detect biomarkers in exhaled breath.
The researchers first developed corresponding ratio fluorescent probes to pinpoint acetone and isopropanol. Then they used 3D printing technology and a smartphone colour recogniser application to realise on-site, sensitive, and semi-quantitative visualisation of biomarkers.
Using the ratio fluorescence strategy, two different colours of fluorescence probes are mixed at an appropriate ratio. When a biomarker like isopropanol is present, it can react with the nicotinamide adenine dinucleotide (NAD+) in the probe and convert it into reduced nicotinamide adenine dinucleotide (NADH) through an enzymatic reaction. This electron transfer from isopropanol to NAD+ will give out a blue emission of NADH, which will turn the red carbon dots on the probe blue. Under optimum conditions, the probe can detect isopropanol levels as low as 4.45 nM. This lower detection limit allows for the early warning of human health.
The team had prepared the ratio probe with carbon dots that pose low toxicity, high luminous efficiency, and organic fluorescent materials with a wide luminous colour range, easy modification of structure, and good tunability.
Combined with the fluorescence sensing platform prepared by the smartphone, it can perform on-site, fast, semi-quantitative, and visual detection.
This method describes a convenient way for real-time detection of biomarkers in exhaled air and is likely to see its applications in potential volatile biomarker research for preliminary monitoring and clinical diagnosis. [APBN]
Source: Yang et al. (2021). Portable Smartphone Platform Based on a Single Dual-Emissive Ratiometric Fluorescent Probe for Visual Detection of Isopropanol in Exhaled Breath. Analytical chemistry.