FU drug delivery enhancement by Ti or C vacancy defects of Ti3C2 MXene nanosheets carriers.

The effect of vacancy defects in Ti₃C₂ MXene as a carrier nanosheet for fluorouracil (in its different forms (Diketo, Ketoenol, and Dienol) in drug delivery systems was studied using Density Functional Theory (DFT). The defects considered in the structure were vacancies of titanium or carbon atoms. Since the electrical and magnetic properties of titanium atoms in the top and bottom layers of Ti₃C₂ differ from those in the middle row, we modeled three carrier nanosheets: two with Ti vacancies and one with C vacancies, to carry each form of the fluorouracil (FU) drug. Compared to the pristine Ti₃C₂ nanocarrier, the adsorption energy of the complexes was enhanced, facilitating drug release. The adsorption energies for complexes containing nanosheets with Ti1 and Ti2 atom vacancies were obtained as -3.99, -2.97, and -1.12 eV for Ti1 vacancies, and -0.24, -0.37, and -0.67 eV for Ti2 vacancies, respectively. For complexes with carbon vacancies, the adsorption energies were -0.27 and -0.49 eV. Furthermore, the results showed that for almost all complexes, the drug began to move away from the carrier nanosheet during the release process in the slightly acidic tumor environment. Only one complex remained stable, consisting of Dienol and nanosheet with Ti1 vacancy with an adsorption energy -0.42 eV in acidic environment and required simultaneous Near-Infrared laser-assisted radiation for drug release. Similar to the pristine Ti₃C₂ carrier, for the nanosheets with vacancies, FU acts as the electron acceptor while the carrier serves as the electron donor. Spin-polarized calculations revealed that the magnetization of the C-vacant nanosheets and one of the Ti-vacant nanosheets remained almost unchanged after FU adsorption, which is advantageous for drug delivery via magnetic hyperthermia. Our findings suggest that Ti₃C₂ MXene nanosheets with vacancy defects, which are more realistic, are promising carriers for fluorouracil and could potentially provide an improved drug delivery system compared to pristine Ti₃C₂ for targeted therapy.