Molecular dynamics study of urea adsorption on nitrogen and phosphorus doped carbon nanotubes for artificial kidney devices

Patients with end-stage renal disease (ESRD) have limited treatment options, primarily dialysis and kidney transplantation. While dialysis effectively removes urea, it remains costly and inconvenient, whereas transplantation is feasible for only a small subset of patients. These challenges underscore the urgent need for innovative blood purification technologies. Wearable artificial kidney (WAK) devices represent a significant advancement, yet efficient urea adsorption remains a critical challenge for their functionality and compact design. In this study, molecular dynamics (MD) simulations were conducted to investigate urea adsorption on nitrogen-doped (N-doped) and phosphorus-doped (P-doped) carbon nanotubes (CNTs). Key analyses—including energy evaluation, radius of gyration ( \:Rg ), radial distribution function (RDF), root-mean-square deviation (RMSD), solvent accessible surface area (SASA) and hydrogen bond (H-bond) assessments—were performed to compare the adsorption capacities of these materials. The results indicate that CNTs with 15% nitrogen doping exhibit superior urea adsorption, attributed to enhanced H-bond formation, reduced \:Rg , increased adsorption energy, and a higher RDF peak. These findings suggest that N-doped CNTs are highly efficient adsorbents for WAK devices, offering promising advancements in blood purification technologies.