Computational Evaluation of Metal Doped Phosphorene-Nanosheets for Cancer Treatment

Abstract

Cancer is known as one of the leading causes of human mortality. The cancer treatments also damage the healthy tissue. So effective theranostic treatments are required for efficient cancer therapy and safety of healthy tissue. Phosphorene is a great material of interest to develop efficient targeted drug delivery system and imaging guided thermal therapy for cancer curing. Metal doping in a material is offered to tune its properties. In this work, effect of group II A metals on targeted delivery of anti-cancer drug, photoimaging (image guided cancer treatment) and photothermal treatment (thermal killing of cells by employing near infrared (NIR) light of doped phosphorene are evaluated via DFT method. The adsorption energies, quantum molecular properties, Atoms in Molecules (AIM) analysis, and Natural Bond Orbital (NBO) analysis of drug loaded pristine and doped phosphorene complexes were explored to understand the type of events in their interactions. The thermodynamic data confirms the exothermic and spontaneous nature of adsorption. The doped complexes showed better adsorption than pristine complex. The polarity was found to increase in doped complexes which is essential for driving in biological systems. Drug adsorption and doping have decreased the chemical potential and electrophilicity index while increased the softness of pristine phosphorene and doped phosphorene. The NBO data indicated the flow of charge from drug to nanosheet. Doping has made suitable the charge transfer and associated interaction. This interaction is strong in neutral pH. At acidic pH, in cancerous tissue environment drug will be protonated and will lose this interaction. These interactions were further investigated by Quantum Theory of Atoms in Molecules (QTAIM) analysis, revealing strong covalent interactions in all doped complexes except for one Mg-O bond in Mg-doped complex which owns strong electrostatic interactions. TD-DFT study showed lowering of band gap and shifting of λmax towards NIR region which is very useful for photothermal and image guided therapy. The Surface-Enhanced Raman Scattering (SERS) analysis revealed that doped systems effectively enhanced the Raman signals. All these properties supported the potential use of doped phosphorene complexes for photoimaging and photothermal killing of cancer cells.