A high loading nanocarrier for the 5-fluorouracil anticancer drug based on chloromethylated graphene.

In the present work, we report a facile and simple strategy to functionalize graphene with the chloromethyl (CH2Cl) functional group as a nanoplatform for effectual loading of the 5-fluorouracil (5-FU) anticancer drug. To achieve the highest loading capacity, hydrochloric acid concentration, the quantity of paraformaldehyde, ultrasonic treatment time, and stirring duration were all carefully optimized. The results revealed that the optimum conditions for functionalizing graphene were obtained at 70 mL of hydrochloric acid, 700 mg of paraformaldehyde, and times of 35 min and 2 h of ultrasonication and stirring. Later, the drug (5-FU) was loaded onto CH2Cl-functionalized graphene through hydrogen bonding and π-π interactions. The chemical structure of the functionalized material and the loading of the 5-FU drug were confirmed by FTIR analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The 5-FU loading capacity of as-prepared materials was determined using the ion chromatography instrument. Our findings demonstrate that chloromethylated graphene is a very excellent nano-platform for high-efficiency drug loading, yielding a loading capacity of 52.3%, comparatively higher than pure graphene (36.54%).

Oxygen adsorption properties of small cobalt oxide clusters: application feasibility as oxygen gas sensors.

In this paper, a theoretical mechanism for oxygen adsorption on small-size cobalt oxide clusters is investigated. For this purpose, we employed dispersion-corrected density functional theory (DFT-D2). In this scheme, van der Waals interactions and the spin polarization mode are activated. Our calculations show the most stable oxygen adsorption configurations on the small-size thermodynamically stable cobalt oxide clusters, which are considered as (CoO)n (n = 2, 3, 4) and (Co3O4)n (n = 1, 2). The equilibrium geometries, adsorption energies, and electronic structures in terms of ionization potential, electron affinity, energy gap, spatial distribution of orbitals, partial density of states of the oxygen molecule, and charge transfer are calculated. Spin-distinct charge transfer is comprehensively studied employing schematic representations of energy levels along with the Lowdin charge analysis and visualization of charge density redistribution near the adsorption sites. Studies indicate that charge is totally transferred from cobalt oxide clusters to oxygen, which consists of spin-up charge transfer from oxygen to the clusters and spin-down charge transfer from the clusters to oxygen. It was seen that upon oxygen adsorption, the energy gap of the clusters increases and therefore conductivity decreases. Also, oxygen chemically adsorbs on the cobalt oxide clusters in an exothermic process. Therefore, oxygen molecules could be detected by pristine cobalt oxide clusters via conductometric and thermoelectric type sensors.