Rapid Detection of Explicit Volatile Organic Compounds for Early Diagnosis of Lung Cancer Using MoSi2N4 Monolayer.

In this study, we investigate the adsorption and sensing capabilities of pristine (MoSi2N4) and nitrogen-vacancy induced (MoSi2N4-VN) monolayers towards five potential lung cancer volatile organic compounds (VOCs), such as 2,3,4-trimethylhexane (C9H20), 4-methyloctane (C9H20), o-toluidine (C7H9N), Aniline (C6H7N), and Ethylbenzene (C8H10). Spin-polarized density functional theory (DFT) calculations reveal that MoSi2N4 weakly adsorb the mentioned VOCs, whereas the introduction of nitrogen vacancies significantly enhances the adsorption energies ( E a d s ${{E}_{ads}}$ ), both in gas phase and aqueous medium. The MoSi2N4-VN monolayers exhibit a reduced bandgap and facilitate charge transfer upon VOCs adsorption, resulting in enhanced E a d s ${{E}_{ads}}$ values of -0.83, -0.76, -0.49, -0.61, and -0.50 eV for 2,3,4-trimethylhexane, 4-methyloctane, o-toluidine, Aniline, and Ethylbenzene, respectively. Bader charge analysis and spin-polarized density of states (SPDOS) elucidate the charge redistribution and hybridization between MoSi2N4-VN and the adsorbed VOCs. The work function of MoSi2N4-VN is significantly reduced upon VOCs adsorption due to induced dipole moments, enabling smooth charge transfer and selective VOCs sensing. Notably, MoSi2N4-VN monolayers exhibit sensor responses ranging from 16.2 % to 26.6 % towards the VOCs, with discernible selectivity. Importantly, the recovery times of the VOCs desorption is minimal, reinforcing the suitability of MoSi2N4-VN as a rapid, and reusable biosensor platform for efficient detection of lung cancer biomarkers. Thermodynamic analysis based on Langmuir adsorption model shows improved adsorption and detection capabilities MoSi2N4-VN under diverse operating conditions of temperatures and pressures.