Chemical Functionalization of Silicon Carbide Nanotube (SiCNT): First Principles DFT Study

Abstract

In this study, a functionalized nano drug carrier design based on (5,5) silicon carbide nanotube and functional groups such as amine (−NH2), hydroxyl (−OH), and carboxylic acid (−COOH) were investigated using the first principles’ density functional theory. The critical need for a smart nanocarrier system aims to increase the concentration of medications to the particular tissues of interest with minimal toxicity to the patient. The simulations are carried out using Quantum ATK-Atomistic Simulation Software. The negative binding energy and the total energy difference obtained by optimization through random perturbation ensure the stability of the structures SiCNT and SiCNT-(X/2X) (X = −OH, −NH2, and −COOH). The energy bandgap obtained for the pristine structure is 1.99 eV indicating their indirect bandgap semiconducting characteristics. In comparison to SiCNT, the energy bandgap of SiCNT-(X/2X) structures decreases within a range of 0.06 eV to 1.95 eV, respectively. Partial charges and p-character were used to understand the nature of bonds between the nanotube and the functional moiety. The chemical potential analysis favors a blue shift of SiCNT-(X/2X) with respect to SiCNT. The higher values of ionic character and solvation energy predicts the solubility of nanostructures in the aqueous medium. In comparison to all analyzed systems, the findings of the ionic character, solvation, and sensing mechanism indicate SiCNT-(2NH2) system to be most favorable drug delivery nanocarrier. These findings suggest that increasing the concentration of −NH2 functional groups on the side wall of silicon carbide nanotubes helps to develop a promising and efficient targeted drug delivery system to deliver specific molecular cargo to the cells mitigating toxicity associated with nanotubes, thereby enhancing the outcomes of cancer treatment. Furthermore, surface functionalization of silicon carbide nanostructures could improve their potential solubility parameterized by higher values of dipole moment and solvation energy together with enhanced biocompatibility leading to the desired therapeutic effect.