(447g) Density Functional Theory Investigation of Mxenes: Amino Acid Adsorption and Mechanical Properties

MXenes, an emerging family of 2D transition metal carbides and nitrides, are of considerable interest in the biomedical community due to their exceptional physiochemical properties. Their unique surface functional groups and larger surface area make MXenes (formula: M_n+1X_nT_x, here “M” denotes the transition metals, “X” denotes C and/or N elements, “T_x” denotes the surface termination groups -O, -OH or -F; n=1-3) potential candidates to be used for biosensors, drug-loading and antibacterial coating applications. While preliminary experimental findings show high biocompatibility of MXenes, there are not many studies on the biocompatibility of MXenes at a molecular level and the exact mechanisms and forces controlling biomolecule-surface interactions for MXenes systems are relatively unknown.[1], [2] As a first step towards exploring these interactions, we have investigated the adsorption of amino acids, the building blocks of proteins, to mono and bilayer Ti₃CN with -O, -OH and -F surface termination using a first principle-based approach.

Specifically, the Adsorption Locator module within Biovia Materials Studio was used to sample adsorption configurational space through Monte Carlo simulation, using the COMPASS and Universal classical force fields.[3]–[5]After identifying the most energetically stable physisorption configurations, these same configurations were used as starting structures for subsequent density functional theory (DFT) quantum chemical calculations. DFT calculations are conducted using the DMOL3 module within Materials Studio.[6] The generalized gradient approximation with PBE functional, Grimme’s DFT-D dispersion correction, and a DNP basis set are used for all calculations.[7]–[9] In addition to vacuum calculations, we have also studied the effect of liquid water solvent on adsorption by implementing the COSMO continuum solvation model.[10]

DFT methods are also widely implemented to theoretically predict the structural and mechanical properties of new materials due to their accuracy (within 10% of experimental).[11], [12] As such, we have also investigated the structural and mechanical properties for our functionalized Ti₃CN systems using DFT to report the archetypal surfaces for biomedical application. A comparative analysis between the binding and structural/mechanical properties of Ti₃CN and graphene will also be presented.

[1] J. Huang, Z. Li, Y. Mao, and Z. Li, “Progress and biomedical applications of MXenes,” Nano Select, vol. 2, no. 8, pp. 1480–1508, Aug. 2021, doi: 10.1002/NANO.202000309.

[2] L. Chen, X. Dai, W. Feng, and Y. Chen, “Biomedical Applications of MXenes: From Nanomedicine to Biomaterials,” Acc Mater Res, vol. 3, no. 8, pp. 785–798, Aug. 2022, doi: 10.1021/ACCOUNTSMR.2C00025/SUPPL_FILE/MR2C00025_SI_001.PDF.

[3] H. Sun, “COMPASS: An ab Initio Force-Field Optimized for Condensed-Phase ApplicationsOverview with Details on Alkane and Benzene Compounds,” Journal of Physical Chemistry B, vol. 102, no. 38, pp. 7338–7364, Sep. 1998, doi: 10.1021/JP980939V.

[4] A. K. Rappé, C. J. Casewit, K. S. Colwell, W. A. Goddard, and W. M. Skiff, “UFF, a Full Periodic Table Force Field for Molecular Mechanics and Molecular Dynamics Simulations,” J Am Chem Soc, vol. 114, no. 25, pp. 10024–10035, Dec. 1992, doi: 10.1021/JA00051A040/SUPPL_FILE/JA00051A040_SI_001.PDF.

[5] https://www.3dsbiovia.com/products/datasheets/adsorption-locator.pdf

[6] B. Delley, “From molecules to solids with the DMol3 approach,” J Chem Phys, vol. 113, no. 18, p. 7756, Oct. 2000, doi: 10.1063/1.1316015.

[7] B. Delley, “An all‐electron numerical method for solving the local density functional for polyatomic molecules,” J Chem Phys, vol. 92, no. 1, p. 508, Aug. 1998, doi: 10.1063/1.458452.

[8] S. Grimme, J. Antony, S. Ehrlich, and H. Krieg, “A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu,” J Chem Phys, vol. 132, no. 15, p. 154104, Apr. 2010, doi: 10.1063/1.3382344.

[9] J. P. Perdew, K. Burke, and M. Ernzerhof, “Generalized Gradient Approximation Made Simple,” Phys Rev Lett, vol. 77, no. 18, p. 3865, Oct. 1996, doi: 10.1103/PhysRevLett.77.3865.

[10] F. Eckert and A. Klamt, “Fast solvent screening via quantum chemistry: COSMO-RS approach,” AIChE Journal, vol. 48, no. 2, pp. 369–385, Feb. 2002, doi: 10.1002/AIC.690480220.

[11] B. Winkler, M. Hytha, M. C. Warren, V. Milman, J. D. Gale, and J. Schreuer, “Calculation of the elastic constants of the Al2SiO5 polymorphs andalusite, sillimanite and kyanite,” Zeitschrift fur Kristallographie, vol. 216, no. 2, pp. 67–70, Feb. 2001, doi: 10.1524/ZKRI.216.2.67.20336/MACHINEREADABLECITATION/RIS.

[12] V. Milman and M. C. Warren, “Elastic properties of TiB2 and MgB2,” Journal of Physics: Condensed Matter, vol. 13, no. 24, pp. 5585–5595, Jun. 2001, doi: 10.1088/0953-8984/13/24/304.