OICC Press Journal of Nanostructure in Chemistry 2193-8865 3 1 (December 2013) 2013 04 25 The interaction between carbon nanotube and skin anti-cancer drugs: a DFT and NBO approach 10.1186/2193-8865-3-22 EN Maryam Hesabi Department of Chemistry, Faculty of Science, Islamic Azad University, Rasht Branch, Rasht, 41476, IR Masoumeh Hesabi Faculty of Nursing, Shahid Beheshti University of Medical Sciences, Rasht Branch, Rasht, 41625, IR Journal Article 2013 04 25 Abstract Nowadays, nanotubes are used widely as container agents to transport bioactive peptides, proteins, nucleic acids, and drugs, and used to deliver their cargos to cells and organs in human bodies. In this work, the possibility of the formation of stable composite between carbon nanotubes and skin anti-cancer drugs has been investigated. The nanotube used in this study includes 60 C atoms of (6,6) type. Density functional theory-based methods (B3LYP/6-31G) show that the composites between drugs (aminolevulinic acid and tretinoin) and nanotube are more stable than the single agents. The difference in the hybridization of C and O atoms can cause to a difference between bond lengths, angles, and charges. The natural bond orbital calculations indicate that some donor atoms (lone pair of oxygen or nitrogen atoms) can transfer electron to acceptor atoms ( σ * or π * in carbon nanotube) and the occupancy of the oxygen lone pair with increasing p orbital share of the lone pair electrons of oxygen decreases. Then, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), the HOMO-LUMO bandgap, and the electronic chemical potential ( μ ) for the lowest energy derived to estimate the structural stability of the composites have been investigated. Results show that nanotube-tretinoin is more stable than nanotube - aminolevulinic acid.