Nanodiamond–Gold Nanocomposites with the Peroxidase-Like Oxidative Catalytic Activity

Novel nanodiamond–gold nanocomposites (NDAus) are prepared, and their oxidative catalytic activity is examined. Gold nanoparticles are deposited on carboxylated nanodiamonds (NDs) by in situ chemical reduction of gold precursor ions to produce NDAus, which exhibit catalytic activity for the oxidation of <i>o</i>-phenylenediamine in the presence of hydrogen peroxide similarly to a peroxidase. This remarkable catalytic activity is exhibited only by the gold nanoparticle-decorated NDs and is not observed for either Au nanoparticles or NDs separately. Kinetic oxidative catalysis studies show that NDAus exhibit a ping-pong mechanism with an activation energy of 93.3 kJ mol^–1, with the oxidation reaction rate being proportional to the substrate concentration. NDAus retain considerable activity even after several instances of reuse and are compatible with a natural enzyme, allowing the detection of xanthine using cascade catalysis. Association with gold nanoparticles makes NDs a good carbonic catalyst due to charge transfer at the metal–carbon interface and facilitated substrate adsorption. The results of this study suggest that diverse carbonic catalysts can be obtained by interfacial incorporation of various metal/inorganic substances

Paclitaxel–Nanodiamond Nanocomplexes Enhance Aqueous Dispersibility and Drug Retention in Cells

Nanodiamonds (NDs) with 5 nm crystalline structures have been recognized as emerging carbon delivery vehicles due to their biocompatible inertness, high surface-to-volume ratio, and energy absorbance properties. In this study, carboxylated nanodiamond (ND–COOH) was reduced to hydroxylated nanodiamond (ND–OH) for stable and pH-independent colloidal dispersity. The poorly water-soluble paclitaxel (PTX) was physically loaded into ND–OH clusters, forming amorphous PTX nanostructure on the interparticle nanocage of the ND substrate. Stable physical PTX loading onto the ND substrate with stable colloidal stability showed enhanced PTX release. ND–OH/PTX complexes retained the sustained release of PTX by up to 97.32% at 70 h, compared with the 47.33% release of bare crystalline PTX. Enhanced PTX release from ND substrate showed low cell viability in Hela, MCF-9, and A549 cancer cells due to sustained release and stable dispersity in a biological aqueous environment. Especially, the IC₅₀ values of ND–OH/PTX complexes and PTX in Hela cells were 0.037 μg/mL and 0.137 μg/mL, respectively. Well-dispersed cellular uptake of suprastructure ND–OH/PTX nanocomplexes was directly observed from the TEM images. ND–OH/PTX nanocomplexes assimilated into cells might provide convective diffusion with high PTX concentration, inducing initial necrosis. This study suggests that poorly water-soluble drugs can be formulated into a suprastructure with ND and acts as a highly concentrated drug reservoir directly within a cell

Energy-Absorbing and Local Plasmonic Nanodiamond/Gold Nanocomposites for Sustained and Enhanced Photoacoustic Imaging

Photoacoustic (PA) imaging is a laser-mediated optical ultrasound-based visualization that allows imaging of optical energy absorbers in deep tissue, offering higher spatial resolution, compared with that of NIR fluorescence. To enhance a gold nanoparticles-based PA agent, carbon crystalline nanodiamonds and gold nanocomposites (NDAuNPs) were synthesized by chemical reduction of a carboxylate nanodiamond and gold precursor. Reduced hydroxyl-terminated nanodiamonds have stable colloidal dispersion and provide a platform where AuNPs are localized on the ND surface with high density. NDAuNP agglutinates were 100 nm in size, and AuNPs with a size distribution of 5–20 nm were chemically conjugated on the ND surface. The surface-enhanced Raman scattering spectra showed enhanced intensity of NDAuNPs in a concentration-dependent manner. Energy-absorbing nanodiamonds facilitated energy transfer into AuNPs, inducing a local plasmonic effect. The PA signal of NDAuNPs was stronger than that of the AuNPs, as well as the signal maintenance during a prolonged period of laser irradiation. Tissue images of TEM showed that after 2 h irradiation NDAuNPs were maintained without gold degradation, while AuNPs were degraded. The local plasmonic and the energy-absorbing properties of NDAuNPs amplified the PA signal and impeded the degradation of gold without PA signal decay. The NDAuNP nanocomposites may serve as an imaging probe, providing high PA amplitudes

Polyamidoamine-Decorated Nanodiamonds as a Hybrid Gene Delivery Vector and siRNA Structural Characterization at the Charged Interfaces

Nanodiamonds have been discovered as a new exogenous material source in biomedical applications. As a new potent form of nanodiamond (ND), polyamidoamine-decorated nanodiamonds (PAMAM-NDs) were prepared for E7 or E6 oncoprotein-suppressing siRNA gene delivery for high risk human papillomavirus-induced cervical cancer, such as types 16 and 18. It is critical to understand the physicochemical properties of siRNA complexes immobilized on cationic solid ND surfaces in the aspect of biomolecular structural and conformational changes, as the new inert carbon material can be extended into the application of a gene delivery vector. A spectral study of siRNA/PAMAM-ND complexes using differential scanning calorimetry and circular dichroism spectroscopy proved that the hydrogen bonding and electrostatic interactions between siRNA and PAMAM-NDs decreased endothermic heat capacity. Moreover, siRNA/PAMAM-ND complexes showed low cell cytotoxicity and significant suppressing effects for forward target E6 and E7 oncogenic genes, proving functional and therapeutic efficacy. The cellular uptake of siRNA/PAMAM-ND complexes at 8 h was visualized by macropinocytes and direct endosomal escape of the siRNA/PAMAM-ND complexes. It is presumed that PAMAM-NDs provided a buffering cushion to adjust the pH and hard mechanical stress to escape endosomes. siRNA/PAMAM-ND complexes provide a potential organic/inorganic hybrid material source for gene delivery carriers

LC/ESI MS/MS of trypsin/Glu-C digests of R27T and Rebif.

<p>(A) Extraction ion chromatogram at m/z 204 and 366 for product ion spectra at 21 min and 46 min, respectively. Amino acid sequencing of deglycosylated C3 and C13 peptides by LC/ESI MS/MS. (B) Deglycosylated C3 peptide MS spectrum and fragmentation information for R27T (Lot: 12104DS01 and 12103DS01) and Rebif. (C) MS spectrum of the deglycosylated C13 peptide and fragmentation information for R27T (Lot: 12104DS01 and 12103DS01) and Rebif.</p

Glycoengineering of Interferon-β 1a Improves Its Biophysical and Pharmacokinetic Properties

<div><p>The purpose of this study was to develop a biobetter version of recombinant human interferon-β 1a (rhIFN-β 1a) to improve its biophysical properties, such as aggregation, production and stability, and pharmacokinetic properties without jeopardizing its activity. To achieve this, we introduced additional glycosylation into rhIFN-β 1a via site-directed mutagenesis. Glycoengineering of rhIFN-β 1a resulted in a new molecular entity, termed R27T, which was defined as a rhIFN-β mutein with two N-glycosylation sites at 80^th (original site) and at an additional 25^th amino acid due to a mutation of Thr for Arg at position 27^th of rhIFN-β 1a. Glycoengineering had no effect on rhIFN-β ligand-receptor binding, as no loss of specific activity was observed. R27T showed improved stability and had a reduced propensity for aggregation and an increased half-life. Therefore, hyperglycosylated rhIFN-β could be a biobetter version of rhIFN-β 1a with a potential for use as a drug against multiple sclerosis.</p></div

Construction and testing of rhIFN-β glycosylation analogs.

<p>(A) A schematic of the rhIFN-β protein. Boxes represented the locations of the five α-helices. Each vertical line represented a position with potential for an additional N-linked glycosylation site, as predicted by NetNGlyc. Introduced N-linked glycosylation consensus sequence sites were showed by diamonds(?). Purified samples were separated by (B) SDS-PAGE and (C) western blot analysis. (D) Analogs were subjected to N-glycanase digestion for the indicated times. (E) IEF analysis was performed over a pH range of 3–10.</p

Model of the N-glycosylated R27T/IFNAR2 complex.

<p>(A) front view and (B) side view. The complex structure oligosaccharides, R27T, and IFNAR2 were shown as orange, magenta, and cyan color, respectively. New hydrogen bonds between the oligosaccharide and complex were presented as red bold line in C (with IFNAR2) and D (R27T). Also, 27T and 80N in R27T protein were colored by yellow (A,B) and hydrogen-bonded residues in R27T and IFNAR2 were colored by green (C,D).</p

<i>In vitro</i> activity.

<p>(A) Anti-viral, (B) anti-proliferative and (C) immunomodulatory activities of R27T (?), R27TΔGlyc (▪) and Rebif (▴).</p

Size distribution of rhIFN-β 1a and R27T.

<p>The analysis of (A) rhIFN-β 1a and (B) R27T was performed at a scattering angle of 90° and distributed sizes, PDI, and Zeta averages were shown. (r.nm: radius in nanometers). (C) rhIFN-βs were quantified by CPE at each time up to 72 hr.</p