Structural and Mechanistic Studies of γ-Fe2O3 Nanoparticle as Capecitabine Drug Nanocarrier

Using density functional theory,noncovalent interactions and four mechanisms of covalent functionalization of capecitabine anticancer drug onto γ-Fe2O3 nanoparticles have been investigated.Quantum molecular descriptors of noncovalent configurations were studied.It was specified that binding of capecitabine onto γ-Fe2O3 nanoparticles is thermodynamically suitable.Hardness and the gap of energy between LUMO and HOMO of capecitabine are higher than the noncovalent configurations,showing the reactivity of capecitabine increases in the presence of γ-Fe2O3 nanoparticles.Capecitabine can bond to γ-Fe2O3 nanoparticles through OH（k1 mechanism）,NH（k2 mechanism）,CO（k3 mechanism） and F（k4 mechanism） groups.The activation energies,activation enthalpies and activation Gibbs free energies of these reactions were calculated.It was specified that the k1 and k2 mechanisms are under thermodynamic control and k3 and k4 under kinetic control.These results could be generalized to other similar drugs.

Mechanistic, Energetic and Structural Aspects of the Adsorption of Carmustine on the Functionalized Carbon Nanotubes

Using density functional theory, noncovalent interactions and two mechanisms of covalent functionalization of drug carmustine with functionalized carbon nanotube（CNT） have been investigated. Quantum molecular descriptors of noncovalent configurations were studied. It was specified that binding of drug carmustine with functionalized CNT is thermodynamically suitable. NTCOOH and NTCOCl can bond to the NH group of carmustine through OH（COOH mechanism） and Cl（COCl mechanism） groups, respectively. The activation energies, activation enthalpies and activation Gibbs free energies of two pathways were calculated and compared with each other. The activation parameters related to COOH mechanism are higher than those related to COCl mechanism, and therefore COCl mechanism is suitable for covalent functionalization. COOH functionalized CNT（NTCOOH） has more binding energy than COCl functionalized CNT（NTCOCl） and can act as a favorable system for carmustine drug delivery within biological and chemical systems（noncovalent）. These results could be generalized to other similar drugs.

A Derivative of s-Triazine Modified Reduced Graphene Oxide with the Function of UV-absorbing

A new s-triazine derivative modified graphene composite, in which 2,4,6-tri（2,4-dihydroxyphenyl）-1,3,5- triazine （TDTA） was attached onto reduced graphene oxide （rGO） via the noncovalent functionalization approach, named TDTA/rGO, was reported. And the TDTA was synthesized via a Friedel-Crafts reaction. FTIR and NMR spectroscopic characterizations were carried out to confirm the synthesis of TDTA. UV-Vis, XPS and TEM revealed that TDTA molecules were successfully loaded onto graphene sheets by π-π stacking, and the composite is found to improve greatly the dispersity ofrGO in DMF and to be a good UV-absorber.

Patterning Functionalized Surfaces of 2D Materials by Nanoshaving

Atomic force microscopy(AFM)and scanning probe lithography can be used for the mechanical treatment of various surfaces,including polymers,metals,and semiconductors.The technique of nanoshaving,in which materials are removed using the AFM tip,is employed in this work to produce nanopatterns of self-assembled monolayers(SAMs)on two-dimensional(2D)materials.The materials used are monolayers of transition metal dichalcogenides(TMDs),namely,MoS_(2)and WS_(2),which are noncovalently functionalized with perylene diimide(PDI),a perylene derivative.The approach involves rastering an AFM probe across the surface at a controlled increased load in ambient conditions.As a result of the strong bond between PDI SAM and TMD,loads in excess of 1|1N are required to pattern the monolayer.Various predefined patterns,including a grating pattern with feature sizes below 250 nm,are demonstrated.Results indicate the high precision of nanoshaving as an accurate and nondestructive lithographic technique for 2D materials.The work functions of shaved heterostructures are also examined using Kelvin probe force microscopy.