A general one-pot, solvent-free solid-state synthesis of biocompatible metal nanoparticles using dextran as a tool: Evaluation of their catalytic and anti-cancer activities.

We propose a general green method coupled with a solid-state vibration ball milling strategy for the synthesis of various metal nanoparticles (MNPs), employing a polymeric carbohydrate dextran (Dx) as a reducing and stabilizing molecule. The synthesis of size-controlled Dx-based MNPs (Dx@MNPs), featuring comparatively narrow size distributions, was achieved by controlling the mass ratio of the reactants, reaction time, frequency of the vibration ball mill, and molecular weight of Dx. Notably, this process was conducted at ambient temperatures, without the aid of solvents and accelerating agents, such as NaOH, and conventional reductants as well as stabilizers. Thermal properties of the resulting Dx@MNPs nanocomposites were extensively investigated, highlighting the influence of metal precursors and reaction conditions. Furthermore, the catalytic activity of synthesized nanocomposites was evaluated through the reduction reaction of 4-nitrophenol, exhibiting great catalytic performance. In addition, we demonstrated the excellent biocompatibility of the as-prepared Dx@MNPs toward human embryonic kidney (HEK-293) cells, revealing their potential for anticancer activities. This novel green method for synthesizing biocompatible MNPs with Dx expands the horizons of carbohydrate-based materials as well as MNP nanocomposites for large-scale synthesis and controlled size distribution for various industrial and biomedical applications.

Aqueous lubrication and wear properties of nonionic bottle-brush polymers.

The usage of aqueous lubricants in eco-friendly bio-medical friction systems has attracted significant attention. Several bottle-brush polymers with generally ionic functional groups have been developed based on the structure of biological lubricant lubricin. However, hydrophilic nonionic brush polymers have attracted less attention, especially in terms of wear properties. We developed bottle-brush polymers (BP) using hydrophilic 2-hydroxyethyl methacrylate (HEMA), a highly biocompatible yet nonionic molecule. The lubrication properties of polymer films were analyzed in an aqueous state using a ball-on-disk, which revealed that BPHEMA showed a lower aqueous friction coefficient than linear poly(HEMA), even lower than hyaluronic acid (HA) and polyvinyl alcohol (PVA), which are widely used as lubricating polymers. Significantly, we discovered that the combination of HA, PVA, and BPHEMA is demonstrated to be essential in influencing the surface wear properties; the ratio of 1 : 2 (HA : BPHEMA) had the maximum wear resistance, despite a slight increase in the aqueous friction coefficient.

Crystal structure and thermal properties of bis-[µ-2-(meth-oxy-carbonyl-hydrazinyl-idene)acetato-κ3 N 1,O:O]bis-[di-aqua-(thio-cyanato-κN)manganese(II)] tetra-hydrate.

The title compound, [Mn2(C4H5N2O4)2(NCS)2(H2O)4]·4H2O (I), exists as a centrosymmetric dimer. Each dimeric unit consists of tridentate (O,O,N)-chelating Schiff bases with symmetry-maintained µ-O-bridged carboxyl-ate anions, terminally bound thio-cyanate anions, and ligated and solvated water mol-ecules. The complex exhibits a distorted octa-hedron geometry and the centrosymmetric µ-O-bridged carboxyl-ate anions connect the two manganese atoms to form an M 2O2 ring. In the crystal, the mol-ecules are inter-linked via strong N-H⋯O and O-H⋯O hydrogen-bonding contacts and weak O-H⋯S inter-molecular inter-actions, forming a three-dimensional mol-ecular network.

Carbon nanotubes in the liquid phase: addressing the issue of dispersion.

The inherent size and hollow geometry with extraordinary electronic and optical properties make carbon nanotubes (CNTs) promising building blocks for molecular or nanoscale devices. Unfortunately, their hydrophobic nature and their existence in the form of agglomerated and parallel bundles make this interesting material inadequately soluble or dispersible in most of the common solvents, which is crucial to their processing. Therefore, various ingenious techniques have been reported to disperse the CNTs in various solvents with different experimental conditions. However, by analyzing the published scientific research articles, it is evident that there is an important issue or misunderstanding between the term "dispersion" and "solubilization". As a result many researchers use the terms interchangeably, particularly when stating the interaction of CNTs with liquids, which causes confusion among the readers, students, and researchers. In this article, this fundamental issue is addressed in order to give basic insight to the researchers who are working with CNTs, as well as to the scientists who deal with nano-related research domains.

Shape-tailoring and catalytic function of anisotropic gold nanostructures.

We report a facile, one-pot, shape-selective synthesis of gold nanoparticles in high yield by the reaction of an aqueous potassium tetrachloroaurate(III) solution with a commercially available detergent. We prove that a commercial detergent can act as a reducing as well as stabilizing agent for the synthesis of differently shaped gold nanoparticles in an aqueous solution at an ambient condition. It is noteworthy that the gold nanoparticles with different shapes can be prepared by simply changing the reaction conditions. It is considered that a slow reduction of the gold ions along with shape-directed effects of the components of the detergent plays a vital function in the formation of the gold nanostructures. Further, the as-prepared gold nanoparticles showed the catalytic activity for the reduction reaction of 4-nitrophenol in the presence of sodium borohydride at room temperature.

Carbon nanotubes: are they dispersed or dissolved in liquids?

Carbon nanotubes (CNTs) constitute a novel class of nanomaterials with remarkable applications in diverse domains. However, the main intrincsic problem of CNTs is their insolubility or very poor solubility in most of the common solvents. The basic key question here is: are carbon nanotubes dissolved or dispersed in liquids, specifically in water? When analyzing the scientific research articles published in various leading journals, we found that many researchers confused between "dispersion" and "solubilization" and use the terms interchangeably, particularly when stating the interaction of CNTs with liquids. In this article, we address this fundamental issue to give basic insight specifically to the researchers who are working with CNTs as well asgenerally to scientists who deal with nano-related research domains.

Shape-tailoring of gold nanostructures: can a detergent act as the reducing or protecting agent?

A commercially available detergent was found to be an effective reducing as well as stabilizing agent for the synthesis of differently shaped gold nanoparticles in an aqueous solution at an ambient condition and the as-prepared gold nanoparticles behave as an efficient catalyst for the reduction reaction of 4-nitrophenol at room temperature.

Cucurbit[7]uril as a tool in the green synthesis of gold nanoparticles.

A simple, green, one-pot synthesis of gold nanoparticles was achieved through the reaction of an aqueous mixture of potassium tetrachloroaurate(III) and the macrocycle cucurbit[7]uril in the presence of sodium hydroxide at room temperature without introducing any kind of traditional reducing agents and/or external energy. The as-prepared gold nanoparticles showed catalytic activity for the reduction reaction of 4-nitrophenol in the presence of NaBH(4), which has been established by visual inspection and UV/Vis spectroscopy. This report is the first for the preparation of gold nanoparticles using cucurbit[7]uril in aqueous media through chemical reduction without employing conventional reducing agents and/or external energy.

Macrocycles as a tool: a facile and one-pot synthesis of silver nanoparticles using cucurbituril designed for cancer therapeutics.

Silver nanoparticles made easy: A simple, effective, and one-pot method toward the synthesis of a defined macrocycle-silver nanoparticle system in water has been described (see figure). Interestingly, cucurbituril (CB)[7]-protected AgNPs showed significantly increased cytotoxicity against MCF-7 and NCI-H358 cancer cells, as demonstrated by models in vitro.

Carbon nanotube and gold-based materials: a symbiosis.

Carbon nanotubes constitute a novel class of nanomaterials with potential applications in many areas. The attachment of metal nanoparticles to carbon nanotubes is new way to obtain novel hybrid materials with interesting properties for various applications such as catalysts and gas sensors as well as electronic and magnetic devices. Their unique properties such as excellent electronic properties, a good chemical stability, and a large surface area make carbon nanotubes very useful as a support for gold nanoparticles in many potential applications, ranging from advanced catalytic systems through very sensitive electrochemical sensors and biosensors to highly efficient fuel cells. Here we give an overview on the recent progress in this area by exploring the various synthesis approaches and types of assemblies, in which nanotubes can be decorated with gold nanoparticles and explore the diverse applications of the resulting composites.

Supramolecular nanoencapsulation as a tool: solubilization of the anticancer drug trans-dichloro(dipyridine)platinum(II) by complexation with beta-cyclodextrin.

A novel, water-soluble trans-platinum complex was synthesized by inclusion complexation with beta-cyclodextrin. The complexation was confirmed by (1)H NMR, FT-IR, TGA, and XRD as well as by SEM and EDX. As the precursor complex is not water-soluble, it is difficult to employ it for biological applications. Here, we report that the encapsulation with cyclodextrin allowed to solubilize the complex to a solubility value of 1.6 mg/mL. Moreover, the cytotoxicity in vitro of the novel inclusion complex indicated a much higher activity after encapsulation.

Thermal decomposition kinetics of hydrazinium cerium 2,3-Pyrazinedicarboxylate hydrate: a new precursor for CeO2.

The thermal decomposition kinetics of N(2)H(5)[Ce(pyrazine-2,3-dicarboxylate)(2)(H(2)O)] (Ce-P) have been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), for the first time; TGA analysis reveals an oxidative decomposition process yielding CeO(2) as the final product with an activation energy of approximately 160 kJ mol(-1). This complex may be used as a precursor to fine particle cerium oxides due to its low temperature of decomposition.