Identification of Lung Cancer Biomarkers by Nanosensors Based on Titanium Carbide (Ti₃C₂T _x ) MXenes

Inspired by the importance of early diagnosis of lung cancer, which is responsible for the most cancer-related deaths worldwide, we propose a nanosensor based on titanium carbide MXenes (Ti3C2Tx; T-x = O, S, F, and OH) capable of detecting selected volatile organic compounds (VOCs) from human breath. A set of representative VOCs, such as 2,3,4-trimethylhexane (C9H20), aniline (C6H7N), ethylbenzene (C8H10), isoprene (C5H8), and o-toluidine (C7H9N), are selected and their adsorption mechanism with Ti3C2Tx has been studied comprehensively by means of first-principles density functional theory calculations. Van der Waals-induced simulations reveal the range of adsorption energies of C9H20 (-0.766 to -0.878) C6H7N (-0.663 to -1.02), C8H10 (-0.653 to -0.877), C5H8 (-0.505 to -3.49), and C7H9N (-0.691 to -1.15 eV) on Ti3C2F2, Ti3C2O2, Ti3C2(OH)(2), and Ti3C2S2, respectively. Intrinsic mechanisms of VOCs adsorption and the corresponding changes in the electronic properties of Ti3C2Tx are studied through charge analysis, density of states, electrostatic potentials, and work function calculations. Further, the sensing behavior of the VOCs with Ti3C2Tx has been explored through statistical thermodynamic analysis for practical applications. Our results clearly show that Ti3C2Tx MXenes hold great potential as efficient nanosensors for the detection of VOCs related to lung cancer diagnosis at an early stage.