Coarse-grained modeling of polystyrene-modified CNTs and their interactions with lipid bilayers.

In the present work, we describe Martini3 coarse-grained models of polystyrene and carboxyl-terminated polystyrene functionalized carbon nanotubes (CNTs) and investigate their interactions with lipid bilayers with and without cholesterol (CHOL) using molecular dynamics simulations. By changing the polystyrene chain length and grafting density at the end ring of the CNTs at two different nanotube concentrations, we observe the translocation of nanoparticles as well as changes in the lipid bilayer properties. Our results show that all developed models passively diffuse into the membranes without causing any damage to the membrane integrity, although high concentrations of CNTs induce structural and elastic changes in lipid bilayers. In the presence of CHOL, increasing CNT concentration results in decreased rates of CHOL transmembrane motions. On the other hand, CNTs are prone to lipid and polystyrene blockage, which affects their equilibrated configurations, and tilting behavior within the membranes. Hence, we demonstrate that polystyrene-functionalized CNTs are promising drug-carrier agents. However, polystyrene chain length and grafting density are important factors to consider to enhance the efficiency of drug delivery.

Polystyrene-modified carbon nanotubes: Promising carriers in targeted drug delivery.

To design drug-delivery agents for therapeutic and diagnostic applications, understanding the mechanisms by which covalently functionalized carbon nanotubes penetrate and interact with cell membranes is of great importance. Here, we report all-atom molecular dynamics results from polystyrene and carboxyl-terminated polystyrene-modified carbon nanotubes and show their translocation behavior across a model lipid bilayer together with their potential to deliver a molecule of the drug ibuprofen into the cell. Our results indicate that functionalized carbon nanotubes are internalized by the membrane in hundreds of nanoseconds and that drug loading increases the internalization speed further. Both loaded and unloaded tubes cross the closest leaflet of the bilayer by nonendocytic pathways, and for the times studied, the drug molecule remains trapped inside the pristine tube while remaining attached at the end of polystyrene-modified tube. On the other hand, carboxyl-terminated polystyrene functionalization allows the drug to be completely released into the lower leaflet of the bilayer without imposing damage to the membrane. This study shows that polystyrene functionalization is a promising alternative and facilitates drug delivery as a benchmark case.

Fullerene translocation through peroxidized lipid membranes.

Recent cytotoxicity research suggests that fullerenes can enter the cell and cross the blood-brain barrier. However, the underlying toxicity mechanism behind the penetration of fullerenes through biological membranes is still not well understood. Here we perform coarse-grained molecular dynamics simulations to investigate the interactions of fullerenes and their polar derivatives (Janus) with model regular and peroxidized bilayers. We show that the translocation of fullerenes and their residence time in bulk water vary depending on the bilayer's peroxidation degree and fullerene polarity. The distribution of fullerenes inside the bilayer is mainly determined by the peroxidation degree and the saturation level of lipid acyl chains. The transport of pristine fullerenes through bilayers occurs at nano timescale while the complete diffusion may not be achieved for Janus fullerenes in micro timescale. As for the toxic response of fullerenes in terms of membrane damage, no mechanical disruption of model bilayers is observed throughout the studied simulation times.

In vitro effects of novel type M-V-O derivatives on Xanthine Oxidase.

Xanthine Oxidase (XO) is related with different diseases such as vascular, gout, nephropathy and renal stone diseases that are relevant to high uric acid levels and oxidative stress. Some common natural inhibitors of xanthine oxidase are known as rosmarinic acid and apigenin. With this study, we aimed to determine inhibitory effects of originally synthesized new generation transition metal vanadates on Xanthine Oxidase (XO) from bovine milk. Because, Xanthine oxidase inhibitors are typically used in the treatment of gout and nephropathy and renal stone diseases linked to hyperuricaemia. We found considerable IC50 constants for inhibition of XO. Among the synthesized compounds, Cu‒V‒O was found to be the most active (IC50 = 7.119 mM) for inhibition of XO.

4-(2,3-Dihydroxybenzyl-ideneamino)-3-methyl-1H-1,2,4-triazol-5(4H)-one.

All the non-H atoms of the title compound, C(10)H(10)N(4)O(3), are almost coplanar, the maximum deviation from planarity being 0.065 (3) Å. The dihedral angle between the aromatic rings is 1.66 (6)°. The mol-ecule adopts the enol-imine tautomeric form with an intra-molecular hydrogen-bonding inter-action between the Schiff base N atom and the hydr-oxy group. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.