Boron-doped Nanodiamond as an Electrode Material for Aqueous Electric Double-layer Capacitors.

Herein, a conductive boron-doped nanodiamond (BDND) particle is prepared as an electrode material for an aqueous electric double-layer capacitor with high power and energy densities. The BDND is obtained by depositing a boron-doped diamond (BDD) on a nanodiamond particle substrate with a primary particle size of 4.7 nm via microwave plasma-assisted chemical vapor deposition, followed by heat treatment in air. The BDND comprises BDD and sp2 carbon components, and exhibits a conductivity above 10-2 S cm-1 and a specific surface area of 650 m2 g-1. Cyclic voltammetry measurements recorded in 1 M H2SO4 at a BDND electrode in a two-electrode system shows a capacitance of 15.1 F g-1 and a wide potential window (cell voltage) of 1.8 V, which is much larger than that obtained at an activated carbon electrode, i.e., 0.8 V. Furthermore, the cell voltage of the BDND electrode reaches 2.8 V when using saturated NaClO4 as electrolyte. The energy and power densities per unit weight of the BDND for charging-discharging in 1 M H2SO4 at the BDND electrode cell are 10 Wh kg-1 and 104 W kg-1, respectively, and the energy and power densities per unit volume of the BDND layer are 3-4 mWh cm-3 and 10 W cm-3, respectively. Therefore, the BDND is a promising candidate for the development of a compact aqueous EDLC device with high energy and power densities.

Amphipathic Nanodiamond Supraparticles for Anticancer Drug Loading and Delivery.

Nanodiamonds (NDs) have been attracting considerable attention due to their outstanding chemical, physical, and physiological properties. Additional functionalization of NDs can be carried out by the self-assembly technique. This study reports a straightforward chemical route for self-assembled supraparticles (SPs) based on ND (ND-SPs) using alkyl carboxylic acids with different aliphatic alkyl chain lengths by carbodiimide chemistry and sonication. Poly(ethylene glycol) (PEG)-modified ND-SPs are synthesized successfully for effective nanodrug formulations with the hydrophobic anticancer drug paclitaxel (PTX). The properties of these ND-SP nanomedicines are investigated thoroughly by complementary analytical, spectroscopic, and microscopic techniques. This simple methodology permitted the application of PEG-modified ND-SP-encapsulating PTX as a potent drug carrier, achieving greater efficacy than commercial Abraxane. Results revealed that the morphology, particle size, and water dispersibility of the prepared ND-SP nanoclusters affect the drug efficacy. These PEG-modified ND-SP nanoclusters serve as novel nanomedicine for a passive drug delivery system as well as anticancer chemotherapy.

Multifunctional Cancer Phototherapy Using Fluorophore-Functionalized Nanodiamond Supraparticles.

In this study, the preparation and characterization of self-assembled supraparticles (SPs) comprising fluorophore-conjugated nanodiamond (ND) nanoclusters are described. The SPs are further used in photohyperthermic, photodynamic, and chemotherapeutic multifunctional tumor therapy systems that use bio-optical-window near-infrared lasers. NDs with surface amino groups are conjugated with various fluorophores via carbodiimide chemistry and are spontaneously transformed into self-assembled ND-based SP (ND-SP) nanoclusters. The fluorophore-functionalized ND-SPs exhibit a uniform particle size, high dispersity in water, and low cytotoxicity. In addition, the energy or electron transfer between fluorophores and NDs can enhance the photothermal conversion efficiency. Further, it is demonstrated that the synthesized ND-SPs strongly fluoresce and penetrate the cellular transmembrane, making them attractive for the targeted delivery of conventional nanomedicines such as albumin-bound paclitaxel (Abraxane) and simple drug-loaded ND conjugates. The near-infrared-light-driven efficiency of the fluorophore-functionalized ND-SPs encapsulating anticancer drugs is confirmed by the targeted eradication of cancer cells both in vitro and in vivo. Thus, the fluorophore-functionalized ND-SP nanoclusters may be proven to be a valuable new therapeutic agent for use in cancer treatment.

Anticancer drug delivery to cancer cells using alkyl amine-functionalized nanodiamond supraparticles.

Nanocarriers have attracted increasing interest due to their potential applications in anticancer drug delivery. In particular, the ability of nanodiamonds (NDs) to spontaneously self-assemble into unique nano-structured architectures has been exploited in the development of nanocarriers. In this context, we synthesized functional supraparticles (SPs) by the self-assembly of alkyl amine-modified NDs for use in anticancer chemotherapy. The structural, physical, and physiological properties of these ND-SPs as well as their high biocompatibility were assessed using microscopic techniques and various characterization experiments. Finally, a model anticancer drug (CPT; camptothecin) was loaded into the ND-SPs to investigate their anticancer efficacy in vitro and in vivo. After incubation of CPT-loaded ND-SPs with cancer cells, a dramatic anticancer effect of ND-SPs was expressed, compared to CPT-loaded ordinary nanocarriers of polyethylene glycol-modified polymer micelles and conventional Intralipid® 20% emulsions containing CPT. Our results demonstrated that ND-SPs may serve as a nanomedicine with significant therapeutic potential.

Self-assembled nanodiamond supraparticles for anticancer chemotherapy.

A nanodiamond (ND) is a promising material for drug delivery applications owing to its relatively low cost, amenability to large-scale synthesis, unique structure, and low toxicity. However, synthesizing drug-loaded ND conjugates with uniform and tunable sizes, high loading capacity, efficacy in drug delivery, and versatility in terms of surface functionalization has been challenging. Here, we show that perfluorooctanoic acid-functionalized NDs spontaneously transform into well-dispersed and biocompatible supraparticle (SP) nanoclusters. We demonstrate that the synthesized ND-based SPs (ND-SPs) exhibit high penetration through the cell membrane and are therefore superior as drug carriers for conventional nanomedicines such as polyethylene glycol and phospholipid-based nanocapsules and simple drug-loaded ND conjugates. We confirm the efficacy of ND-SPs in the eradication of cancer cells in vitro and in vivo. Our results demonstrate that the synthesized ND-SPs are useful for targeted drug delivery in a variety of biological applications.

Pestalotiopsin a. Enantioselective construction of potential building blocks derived from antipodal cyclobutanol intermediates.

D-Glyceraldehyde acetonide has been used as the starting point for accessing the enantiomeric cyclobutanols 11 in optically pure condition. The dextrorotatory enantiomer has been transformed in five steps into the [3.2.0] bicyclic lactone 22. While the deoxygenation of 22 proved to be problematical, the uncyclized variant 25 underwent the Barton process smoothly. These findings guided the related conversion of (-)-11 into 34. Use was also made of ring-closing metathesis to bring about the conversion of (+)-11 into [4.2.0] bicyclic lactone building blocks. In general, all three pathways are efficient and offer the prospect of practical side-chain appendage for the purpose of installing the nine-membered ring of pestalotiopsin A (1).

In pursuit of pestalotiopsin a via zirconocene-mediated ring contraction.

[reaction: see text] An asymmetric route from the epimeric beta-hydroxy esters 4 and 5 to the densely functionalized (+)-10 and (-)-10, respectively, is described. Either cyclobutanol can be made available as the predominant product. The levorotatory antipode has been transformed into the advanced intermediate 21 bearing side chains destined to become incorporated into the cyclononene ring of the title compound (1).

"Chiral perturbation factor" approach reveals importance of entropy term in stereocontrol of the 2,4-pentanediol-tethered reaction.

The stereocontrol mechanism of the 2,4-pentanediol (PD)-tethered reaction was studied in detail using a reaction system consisting of phenyl and rhodium carbenoid moieties. Different tethers were examined to analyze the effects of the methyl groups on the PD tether. Among the reactions with these tethers, the PD tether achieves an unmeasurably high stereoselectivity in a diastereomeric ratio of >500. Another tether showing a high but measurable stereoselectivity in a ratio of 41 is mostly controlled by the entropy term. To clarify the role of the methyl groups on the chiral tethers, which are the origin of the stereocontrol, the "chiral perturbation factor" is introduced. This parameter is defined as the rate of a chiral reaction relative to that of an achiral reference reaction. By analyzing the temperature dependence of the chiral perturbation factors for different chiral-tethered reactions, high potentials of the PD-tethered reaction in its stereocontrol are concluded to be due to the entropy term.