Adsorption of Folic Acid on the Single-walled Carbon Nanotubes: AIM and NBO Analyses via DFT

In the present work, the behavior of folic acid （FA） molecule adsorbed onto single-walled carbon nanotube （SWCNT） was examined using the DFT-B3LYP/6-31G＊ level. In order to obtain information about the binding features of SWCNT as adsorbent with FA molecule, several studies, including the structural and electronic parameters and also the Atoms in Molecules （AIM） analysis, were performed. It was observed that the FA molecule via hydrogen bond prefers to adsorb on SWCNT with adsorption energy of about -18.70 kcal/mol. The molecular orbitals （HOMO and LUMO）, natural bond orbital （NBO）,analysis, and density of states （DOS） plot indicated that a charge about 0.032 [ e [ is transferred from the FA molecule to the nanotube. After solvation energy calculations, it was found that the presence of a polar solvent causes an increase in FA adsorption on the single-walled carbon nanotube. Topological features such as electron energy density （Hc） and Laplacian of the electron density （V2p~） demonstrate partial covalent nature for H（ll6）...O（10） interaction in the FA/SWCNT complex. According to the calculated results, the single-walled carbon nanotubes are expected to be a potential efficient adsorbent for the adsorption of folic acid drug and also can be used as a suitable drug delivery vehicle within biological systems.

Boron Nitride Nanotubes as Novel Vectors for Drug Delivery of Amino Acids：A First Principles Simulation

The first principles calculations based on density functional theory（DFT） were performed for investigating the interaction of amino acids with（5, 5） armchair and（8, 0） zigzag boron nitride nanotubes（BNNTs）. Findings showed that the adsorption and solvation energies were negative for（5, 5）/（8,0） BNNTs-amino acid complexes, implying the thermodynamic favorability and spontaneous interactions of amino acids with BNNTs sidewall. Based on calculated results, the BNNTs are expected to be a potential efficient adsorbent as well as a suitable drug delivery vehicle for the adsorption of amino acids within biological systems.

Molecular Structure and Theoretical Thermodynamic Study of Folic Acid Based on the Computational Approach

In our previous work, we studied the interaction of folic acid, FA, molecule with single- walled carbon nanotube and the related binding energies with other related parameters. Now, in order to extend our study with respect to the other structural properties of folic acid molecule and its thermodynamic properties, we optimized the structures of both neutral and zwitteronic forms of this molecule by using the DFT/B3LYP method in the gas phase and then in different solvents. In addition, the electronic properties, such as the molecular orbital study （HOMO, LUMO, PDOS, and TDOS） and geometrical structure, were investigated by the above-mentioned method with 6-3 l G（d） basis set. The thermodynamic properties of both neutral and zwitterionic forms of the FA molecule at different temperature have been calculated. Natural bond orbital （NBO） analysis has been done to study the stability of the molecule arising from charge delocalization.

Adsorption Properties and Quantum Molecular Descriptors of the Folic Acid Drug Adsorbed onto Zigzag and Armchair Single Walled Carbon Nanotubes:DFT Simulations

The adsorption behavior of folic acid onto（5,0） zigzag and（5,5） armchair carbon nanotube（SWCNT） has been investigated using B3 LYP density functional at the 6-31G＊ level. The adsorption energies,molecular orbital analysis and structural changes at the adsorption site are indicative of covalent adsorption on the zigzag SWCNT surface,while the adsorption is physical on the armchair SWCNT surface. The density of states（DOS） Plot and the quantum molecular descriptors（QMD） are witness to the significant changes in the electronic properties of SWCNT systems after the attachment of adsorbed species to the tube surface. According to the calculated results,the single-walled carbon nanotubes are expected to be a potential efficient adsorbent for the adsorption of folic acid drug and also can be used as a suitable drug delivery vehicle within biological systems.

Fullerene(C60) as a Potential Chemical Sensor for Hydrogen Cyanide Detection

To find a novel sensor for the detection and control of toxic hydrogen cyanide(HCN), the geometrical and electronic parameters of HCN adsorption on fullerene C60 were investigated using density functional theory(DFT) calculations by means of B3 LYP functional with 6-31 G* basis set. The calculated density of states(DOSs) shows that the electronic properties of fullerene C60 were very sensitive to the presence of HCN molecule, so that the Eg of C60 was significantly decreased from 2.76 eV in pristine form to 1.81 eV(34.4% change) after the HCN adsorption which would result in electrical conductance increment. The results demonstrated that the C60 may convert the presence of a HCN molecule to an electrical signal for using in HCN-sensor devices through doping, chemical functionalization. Also, based on calculated results, the C60 is expected to be a potential efficient adsorbent as well as a sensor for detecting the presence of toxic HCN.