1
Priyanka Shaw 1 , Ronjini Dasgupta 1 , Saivi Singh 1 , Sabista Ahmad 1 , Arindam Kushagra 2*
Amity Institute of Biotechnology, Amity University Kolkata, West Bengal - 700135; 2 Amity Institute of Nanotechnology, Amity University Kolkata, West Bengal - 700135 *arindam.kushagra@gmail.com
WHAT?
WHY? Easy visual analysis
Porphyrins are substituted macrocyclic compounds which can be easily produced in the lab. Some of the most common examples found in nature are chlorophyll and haeme (in haemoglobin).
Inexpensive
Quicker results
User friendly
Non invasive
Elastomer layer
Volatile Organic Compounds (VOCs) are chemicals that have a high vapor pressure at room temperature.
Before reaction
Changes in hydrophobicity, ion content, acidity, etc., inclusion of various substituent groups and presence of other solutes in a given solvent can lead to changes in absorbance spectrum of the porphyrin.
3-D COLORIMETRIC NOSE FOR COVID-19 DETECTION
Most diseases involve generation of VOCs released by the body through breath and other body wastes. We can thus diagnose those diseases using non-invasive techniques like colorimetric analysis of the VOCs in breath.
[1]
Colour changed
αβ
senotek ro sedyhedla rof eyd enilinA sretse ro slohocla rof seyd cimorhcotavloS
srosnes Hp
sedyhedla detarutasnu- , rof srosnes RN/PN uA
[2]
After reaction [2]
(E)-2-hexanal (Z)-3-hexanal
Even isomers react with the porphyrin to yield a unique set of spectral changes or “fingerprint” making compound recognition possible.
1-hexanal E-2-hexenol Benzaldehyde
Before
4-ethylguaiacol
After
COVID-19 is the worst pandemic that the world has witnessed in the last century after the Spanish flu in 1918. It has paralysed the whole planet and all human activities have come to a standstill. There is a dire need for a rapid and non-invasive detection method. Current testing regimens usually require nasopharyngeal swabs performed by a trained person and a reverse transcription polymerase chain reaction (RT-PCR) test for pathogen identification. Other cellular ingredients also need to be analyzed to detect SARS-CoV- 2 infection. Earlier, dogs have been trained to detect COVID-19 with a relatively high degree of accuracy.[3] Respiratory viral infections in humans generate volatile organic [4] compounds (VOCs). We propose a faster, reliable, non-invasive, and versatile screening tool. Infection-related VOC can be measured in exhaled breath. The proposed device comprises of porous elastomer (hydrogel or PDMS) layers, each of which is impregnated with a particular type of porphyrin. Every VOC will have a unique porphyrin counterpart, thus resulting in unique color generation in different layers. The rationale for measuring VOC profiles in elastomer matrices is to identify unique VOC fingerprints which are associated with COVID-19 infection. In countries with limited access to diagnostic tests, the proposed device has the potential for effective and reliable large scale detection of infected people. The proposed device can not only give the result within minutes, but also the patient doesn't have to undergo the painful swab test. Breath tests are non-invasive and also suitable for identification of asymptomatic and pre-symptomatic individuals.
HOW?
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1
The first step is to blow into the breath analyzer when you want to check for a suspected infection. The exhaled air contains VOCs.
[1]
2
Each elastomer layer consists of a single type of porphyrin. The absorbance and fluorescence spectra of porphyrins are sensitive to binding of VOCs such as ethanol, acetone, etc. in the central ring position and addition of substituent groups to the macrocycle.
N.A. Rakow, K.S. Suslick, Nature 406, 710-713 (2000) [2]
1 2 3 4 5
Z. Li et al. Nat. Plants 5, 856-866 (2019)
I
REFERENCES
I
3
A VOC reacts only with a specific type of porphyrin. Upon reacting, colour of the layers change indicating a particular range of infections a person might be having. The sensitivity of the porphyrin molecules render them ideal for use as indicators in absorbance or fluorescence spectroscopy.
[3]
P. Jendrny et al. BMC Infect. Dis. 20, 536 (2020)
[4]
S. Traxler et al. Sci. Rep. 9, 18894 (2019)