A rational design of metal doped C20 fullerene based sensor for the selective detection of ethyl butyrate as COVID-19 biomarker

The detection of ethyl butyrate as a COVID-19 biomarker in exhaled breath could be a novel, rapid, less expensive, painless and non-invasive technique compared to a costly, painful and time-consuming PCR test. The potential of alkaline earth metals doped C 20 fullerenes (M@C20) 20 ) was explored as sensing materials to detect ethyl butyrate selectively. The ethyl butyrate (EB) exhibited the physisorption on pristine C 20 fullerene with adsorption energy of-4.16 kcal/mol, while chemisorption was observed with M@C20 20 fullerenes. The frontier molecular orbital analysis demonstrates enhanced stability of complexes, attributed to widened Eg g gaps during EB adsorption onto M@C20 20 fullerenes. The notable shift in lambda max values in the visible region suggests using M@C20 20 fullerenes as UV-visible-based naked-eye sensors. The infrared analysis showed a red shift in the carbonyl bond stretching frequency of ethyl butyrate upon adsorption onto M@C20 20 fullerenes. The red shift resulted from charge transfer from ethyl butyrate to M@C20. 20 . These findings establish the foundation for utilizing M@C20 20 fullerenes in IR-based handheld sensing devices. The minimum recovery time (6.8 s) demonstrates Ca@C20 20 fullerene as a promising, reusable sensor for detecting ethyl butyrate at human body temperature. Our results pave the way to design rapid, reusable sensors for detecting ethyl butyrate.