Context The interaction between phytochemicals and nanoparticles plays a crucial role in nanotechnology and biomedical applications. This study investigates the binding behavior and stability of six phytochemicals-Catechin, Limonene, Sabinene, Sinapic Acid, Vanillic Acid, and Luteolin 7-O-ss-glucuronide-with Er2O3 nanoparticles using Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations. The findings indicate that Luteolin, Catechin, and Sinapic Acid exhibit the strongest binding affinities and highest structural stability with Er2O3, attributed to their balanced hydrophilicity-lipophilicity and favorable electronic properties. These insights contribute to the design and functionalization of phytochemical-based nanomaterials, with potential applications in drug delivery, bioimaging, and photodynamic therapy. Methods DFT calculations were conducted using Gaussian 09 at the B3LYP/6-311 + + G(d,p) level to determine HOMO-LUMO energy gaps, dipole moments, and polarizability of the phytochemicals. MD simulations, performed using GROMACS 2019 with the CHARMM36 force field and TIP3P water model, analyzed the dynamics of phytochemical adsorption on a 5 nm Er2O3 nanoparticle over 50 ns. Key parameters such as interaction energies, root mean square deviations (RMSD), radial distribution functions (RDF), and water solubility (logS) were evaluated using ALOPGPS 2.1 software.