Role of vacancy and strain engineering in the adsorption of DNA/RNA nucleobases and amino-acid molecules on Ti2C MXene surfaces

Despite numerous theoretical studies on two-dimensional materials such as graphene, phosphorene, and MoS2 for the detection of deoxyribonucleic acid (DNA)/ribonucleic acid (RNA) nucleobases and amino-acid molecules, the potential of Ti2C MXene remains unexplored, particularly under vacancy-defect and strain engineering. Due to the metallic nature and chemically active and tunable surface of Ti2C MXene in comparison to other two-dimensional counterparts, efficient charge transfer occurs upon adsorption of biomolecules, making it a promising material for detection and sensing applications. Therefore, in this work, we have investigated the atomic and electronic structures, energetics, and adsorption behavior of DNA/RNA nucleobases and amino-acid molecules on pristine, vacancy-defective, and biaxially strained Ti2C MXene using first-principles density functional theory. Our results demonstrate that the creation of vacancy-defects significantly enhances the adsorption strength of adsorbed molecules, while the strain engineering has modulated the adsorption behavior differently under compressive and tensile strains. Specifically, compressive strain has strengthened the adsorption strength, whereas tensile strain has decreased it. Furthermore, electronic structure calculations reveal that the metallic nature of the system is preserved, despite vacancy-defect and strain engineering, which is important for sensing and detection applications. The charge density difference calculations reveal a significant amount of charge transfer between substrate and biomolecules, accompanied by variations in work function for pristine, defective, and strained systems. This theoretical study enhances the deep understanding and prediction of capture and detection of biomolecules on pristine, vacancy-defective, and strained Ti2C MXene surfaces, which would help experimentalists to develop more efficient MXene-based irreversible cumulative dosimeters in the future.