Ceria nanoparticles are important catalysts and nanozymes, exhibiting a strong affinity for various harmful species. The fate of nanomaterials upon their entry into the biological environment raises growing concerns, making it essential to understand their interactions with proteins and other biological molecules, as this may influence the behaviour of the nanoparticles once inside the body. Therefore, the research presented in this thesis focusses on the adsorption of 20 amino acids in their dissociated forms on the three most stable {111}, {110}, and {100} surfaces of cerium oxide. All calculations were conducted using density functional theory as there is not an available potential model that works for the interaction of amino acids and ceria. The three surfaces behave very similarly when it comes to the adsorption configurations. However, the strength of the adsorption is generally stronger on the {100} surface compared to the {110} surface and followed by the {111} surface. The findings reveal that the dissociated amino acids exhibit stronger adsorption when the amino, the carboxyl and the side chain R-groups are all adsorbed on the surfaces of ceria. However, this is amino acid dependent as some amino acids also demonstrate significant strength in their adsorption on the surfaces when adsorbed via the carboxyl and amino groups. The amino acids display both monodentate and bidentate adsorption configurations, however it remains unclear to what extent they affect the adsorption as all configurations are complex. Finally, the hydrogen bond network originating from either the amino group or the R-group contribute additional stability to the adsorption of amino acids on ceria surfaces.