Semisynthesis and antitumor activity of endertiin B and related triterpenoids from Ganoderma lucidum.

Ganoderma lucidum, a fungus used in traditional Chinese medicine, is known for its medicinal value attributed to its active components called Ganoderma triterpenoids (GTs). However, the limited isolation rate of these GTs has hindered their potential as promising drug candidates. Therefore, it is imperative to achieve large-scale preparation of GTs. In this study, four GTs were effectively synthesised from lanosterol. The antitumor activity of these GTs was evaluated in vivo. Endertiin B exhibited potent inhibitory activity against breast cancer cells (9.85 ± 0.91 µM and 12.12 ± 0.95 µM). Further investigations demonstrated that endertiin B significantly upregulated p21 and p27 and downregulated cyclinD1 expression, arresting the cell cycle at the G0/G1 phase and inducing apoptosis by decreasing BCL-2 and increasing BAX and BAK levels. Additionally, endertiin B was found to reduce the expression of proteins associated with the PI3K-AKT signaling pathway. To summarize, endertiin B effectively inhibited cell proliferation by blocking the cell cycle and inducing apoptosis through the PI3K-AKT pathway.

Redox Properties of TiO2 Thin Films Grown on Mesoporous Silica by Atomic Layer Deposition.

The redox properties of titania films grown by ALD on SBA-15, a silica-based mesoporous material, were characterized as a function of thickness (that is, the number of ALD cycles used). 29Si CP/MAS NMR helped to identify the nature of the surface species that form in the initial stages of deposition, and infrared absorption spectroscopy was used to follow the transition from silica to titania surfaces. The reducibility of the titania sites by CO and H2 was studied ex situ using EPR and in situ with ambient-pressure XPS. It was determined that the titania ALD films are amorphous and easier to reduce than crystalline titania and that the reduction is reversible. A transition in the nature of the surface was also observed, with unique mixed Si-O-Ti sites forming during the first few ALD cycles and a more typical titania surface progressively developing as the film grows in thickness.

ATP supplementation suppresses UVB-induced photoaging in HaCaT cells via upregulation of expression of SIRT3 and SOD2.

BACKGROUND: Skin photoaging is the damage caused by excessive exposure to ultraviolet (UV) irradiation. We investigated the effect of adenosine triphosphate (ATP) supplementation on UVB-induced photoaging in HaCaT cells and its potential molecular mechanism. MATERIALS AND METHODS: The toxicity of ATP on HaCaT cells was examined by the MTT assay. The effects of ATP supplementation on the viability and apoptosis of HaCaT cells were determined by crystal-violet staining and flow cytometry, respectively. Cellular and mitochondrial ROS were stained using fluorescent dyes. Expression of Bax, B-cell lymphoma (Bcl)-2, sirtuin (SIRT)3, and superoxide dismutase (SOD)2 was measured via western blotting. RESULTS: ATP (1, 2 mM) exerted no toxic effect on the normal growth of HaCaT cells. UVB irradiation caused the apoptosis of HaCaT cells, and ATP supplementation inhibited the apoptosis induced by UVB significantly, as verified by expression of Bax and Bcl-2. UVB exposure resulted in accumulation of cellular and mitochondrial reactive oxygen species (ROS), but ATP supplementation suppressed these increases. Expression of SIRT3 and SOD2 was decreased upon exposure to UVB irradiation but, under ATP supplementation, expression of SIRT3 and SOD2 was reversed, which was consistent with the reduction in ROS level observed in ATP-treated HaCaT cells after exposure to UVB irradiation. CONCLUSIONS: ATP supplementation can suppress UVB irradiation-induced photoaging in HaCaT cells via upregulation of expression of SIRT3 and SOD2.

Targeting the TNF-α-TNFR interaction with EGCG to block NF-κB signaling in human synovial fibroblasts.

The tumor necrosis factor alpha (TNF-α)-TNF-α receptor (TNFR) interaction plays a central role in the pathogenesis of various autoimmune diseases, particularly rheumatoid arthritis, and is therefore considered a key target for drug discovery. However, natural compounds that can specifically block the TNF-α-TNFR interaction are rarely reported. (-)-Epigallocatechin-3-gallate (EGCG) is the most active, abundant, and thoroughly investigated polyphenolic compound in green tea. However, the molecular mechanism by which EGCG ameliorates autoimmune arthritis remains to be elucidated. In the present study, we found that EGCG can directly bind to TNF-α, TNFR1, and TNFR2 with similar µM affinity and disrupt the interactions between TNF-α and TNFR1 and TNFR2, which inhibits TNF-α-induced L929 cell death, blocks TNF-α-induced NF-κB activation in 293-TNF-α response cell line, and eventually leads to inhibition of TNF-α-induced NF-κB signaling pathway in HFLS and MH7A cells. Thus, regular consumption of EGCG in green tea may represent a potential therapeutic agent for the treatment of TNF-α-associated diseases.

Nucleation and Initial Stages of Growth during the Atomic Layer Deposition of Titanium Oxide on Mesoporous Silica.

A chemical approach to the deposition of thin films on solid surfaces is highly desirable but prone to affect the final properties of the film. To better understand the origin of these complications, the initial stages of the atomic layer deposition of titania films on silica mesoporous materials were characterized. Adsorption-desorption measurements indicated that the films grow in a layer-by-layer fashion, as desired, but initially exhibit surprisingly low densities, about one-quarter of that of bulk titanium oxide. Electron microscopy, X-ray diffraction, UV/visible, and X-ray absorption spectroscopy data pointed to the amorphous nature of the first monolayers, and EXAFS and 29Si CP/MAS NMR results to an initial growth via the formation of individual tetrahedral Ti-oxide units on isolated Si-OH surface groups with unusually long Ti-O bonds. Density functional theory calculations were used to propose a mechanism where the film growth starts at the nucleation centers to form an open 2D structure.

A dual-signal output ratiometric electrochemiluminescent sensor for NADH detection.

Ratiometric electrochemiluminescence (ECL) has attracted great attention in the field of electrochemical analysis. In this study, a dual-signal-output ratiometric ECL sensor was developed for the detection of nicotinamide adenine dinucleotide (NADH). Nitrogen-doped graphene quantum dots (NGQDs) exhibit double ECL signal output capability, without the requirement of additional coreactants. NADH can amplify the anodic ECL response of NGQDs, while it can diminish the cathodic ECL response of NGQDs. Based on the principle between relative enhancing ECL intensity ratio and NADH concentrations, the constructed ratiometric ECL sensor was applied to NADH assays, with a wide concentration range of 10-400 µM and a low limit of detection (LOD) of 2.5 µM (S/N = 3). Furthermore, the proposed method was applied for the determination of spiked NADH, which was proved to be feasible in the biological sample matrix. The proposed strategy of modulating multiple-ECL signals of the single NGQD emitter not only provides a new ECL system for the accurate detection of NADH but also broadens the design pathway for ratiometric sensing fabrication.

Chemical Treatment of Low-k Dielectric Surfaces for Patterning of Thin Solid Films in Microelectronic Applications.

A protocol has been developed to selectively process low-k SiCOH dielectric substrates in order to activate or deactivate them toward the deposition of thin solid films by chemical (CVD or ALD) means. The original SiCOH surfaces are hydrophobic, an indication that they are alkyl- rather than silanol-terminated and that, consequently, they are fairly unreactive. However, the chemical-mechanical polishing (CMP) sometimes done during microelectronics fabrication renders them hydrophilic and reactive. It was shown here that silylation of the CMP-treated surfaces with any of a number of well-known silylation agents such as HMDS, ODTS, or OTS caps the reactive silanol surface groups and turns them back to being hydrophilic and unreactive. Further exposure of any of the passivated surfaces to a combination of ozone and UV radiation reinstates their hydrophilicity and chemical activity. Importantly, it was also demonstrated that all these changes could be induced without altering the original mechanical, optical, or electrical properties of the samples: atomic force microscopy (AFM) images show no increase in roughness, ellipsometry measurements yield the same values for the index of refraction and dielectric constant, and infrared absorption spectroscopy attests to the preservation of the organic fragments present in the original SiCOH samples. The chemical selectivity of the resulting surfaces was tested for the atomic layer deposition (ALD) of HfO2 films, which could be grown only on the UV/O3 treated substrates.

Interface of on line coupling capillary electrophoresis with hydride generation electrothermal atomic absorption spectrometry and its application to arsenic speciation in sediment.

A novel interface for on line coupling capillary electrophoresis with hydride generation electrothermal atomic absorption spectrometry (CE-HG-ETAAS) has been developed. The interface performance was examined in detail. The technique could be used to convert arsenic compounds from CE separation to corresponding volatile hydrides determined by HG-ETAAS. This paper aims to explore the best condition in the speciation analysis of inorganic arsenic by using CE-HG-ETAAS. The application of the developed CE-HG-ETAAS to inorganic arsenic speciation in sediment was investigated. The detection limits of As(III) and As(V) were 135 ng/g and 160 ng/g, respectively. Relative standard deviations of arsenic speciation were better than 2%. The recoveries of As(III) and As(V) in the sample with spiking concentration of 2500 ng/g As(III) and 5000 ng/g As(V) were 97.6% and 96.7%, respectively.

Tuning electron transport in graphene-based field-effect devices using block co-polymers.

Graphene possesses many remarkable properties and shows promise as the future material for building nanoelectronic devices. For many applications such as graphene-based field-effect transistors (GFET), it is essential to control or modulate the electronic properties by means of doping. Using spatially controlled plasma-assisted CF(4) doping, the Dirac point shift of a GFET covered with a polycrystalline PS-P4VP block co-polymer (BCP) [poly(styrene-b-4-vinylpyridine)] having a cylindrical morphology can be controlled. By changing the chemical component of the microdomain (P4VP) and the major domain (PS) with the CF(4) plasma technique, the doping effect is demonstrated. This work provides a methodology where the Dirac point can be controlled via the different sensitivities of the PS and P4VP components of the BCP subjected to plasma processing.

Activation of Metal-Organic Precursors by Electron Bombardment in the Gas Phase for Enhanced Deposition of Solid Films.

The incorporation of gas-phase electron-impact ionization and activation of metal-organic compounds into atomic layer deposition (ALD) processes is reported as a way to enhance film growth with stable precursors. Specifically, it is shown here that gas-phase activation of methylcyclopentadienylmanganese tricarbonyl, MeCpMn(CO)3, which was accomplished by using a typical nude ion gauge employed in many ultrahigh-vacuum (UHV) studies, enhances its dissociative adsorption on silicon surfaces, affording the design of ALD cycles with more extensive Mn deposition and at lower temperatures. Significantly higher Mn uptakes were demonstrated by X-ray photoelectron spectroscopy (XPS) on both silicon dioxide films and on Si(100) wafers Ar(+)-sputtered to remove their native oxide layer. The effectiveness of this electron-impact activation approach in ALD is explained in terms of the cracking patterns seen in mass spectrometry for the metal-organic precursor used.

Chemoselective fabrication of high density peptide microarray by hetero-bifunctional tetra(ethylene glycol) linker for click chemistry conjugation.

A hetero-bifunctional tetra(ethylene glycol) molecule with silane and azide termini was synthesized, and this molecule was used to prepare azide-derivatized glass surface in one step. The resulting glass surface was available for fabricating peptide microarray by the conjugation with alkyne-containing peptide using click chemistry, which proceeded to the completion at low temperature and in aqueous solution. A high density of peptide on the surface was achieved due to concise overall procedure and highly efficient conjugation reaction. Immobilized peptides were highly bio-functional on the surface, as demonstrated by the ability to detect protease activity. Due to the biologically orthogonal manner of conjugation, peptide conjugated by site-specific immobilization was more accessible by protease than that conjugated by random amide conjugation. This site-specific and high efficient immobilization technique could be expanded to large scale development of biocompatible peptide and protein arrays for use in various applications.

A new picrotoxane-type sesquiterpene from Dendrobium findlayanum.

A new picrotoxane-type sesquiterpene, findlayanin (1), was isolated from Dendrobium findlayanum with crystallinin (2). The structure of compound 1 was established to be (1R,2S,3R,4S,5R,6S,9R)-2,3,11,12-tetrahydroxypicrotoxan-12(15)-lactone by spectroscopic methods.

Gas-surface chemical reactions at high collision energies?

Most gas-surface chemical reactions occur via reaction of adsorbed species to form a thermal-energy ( approximately kT) product; however, some instances exist where an energetic projectile directly reacts with an adsorbate in a single-collision event to form a hyperthermal product (with a kinetic energy of a few eV). Here we show for the first time that 30-300 eV F(+) bombardment of fluorinated Ag and Si surfaces produces "ultrafast" F(2)(-) products with exit energies of up to 90 eV via a multistep direct-reaction mechanism. Experiments conclusively show that the projectile F atom ends up in the fast molecular product despite the fact that the impact energy is far greater than typical bond energies.

[Effects of PBD on the luminescence properties of PVK: Ir(ppy)3].

The effects of PBD on the luminescence properties of PVK : Ir(ppy)3 codoped with PBD with lower concentration were investigated. Two kinds of devices with the structures of ITO/PVK : Ir(ppy)3/PBD/Al and ITO/PVK : Ir(ppy)3 : PBD/ Al were fabricated. PVK emission appears in the electroluminescence (EL) spectra of ITO/PVK : Ir(ppy)3/PBD/Al. The reason is that the Forster energy transfer is not efficient enough in the emission layer, and then the emission layer was doped with PBD. A set of devices were fabricated with the configuration of ITO/PVK : Ir(ppy)3 : PBD/BCP/Al. The doping weight ratio of PVK : Ir(ppy)3 was fixed as 100 : 1, and the weight ratio of PBD changed from 100 : 0 (PVK : PBD) to 100 : 20. The photoluminescence (PL) spectra and electroluminescence (EL) spectra of these devices were measured. Through the analysis of their luminescence, it was found that the brightness of these devices codoped with PBD is improved. The brightness of these devices increases with increasing PBD doping ratio as the ratio does not exceed 100:10 (PVK : PBD). The PBD codoping enhances the injection and transportation of electron, resulting in the enhanced carrier recombination probability. If the doping ratio of PBD exceeds 100 : 10 (PVK : PBD), the brightness of the device decreases. There are two reasons. One is that the superfluous PBD causes the carriers to be imbalanced and induces a larger leakage current. The other is that the superfluous PBD may block the hoping of holes or electrons between the PVK chains. The brightness is the strongest when the weight ratio of PVK to PBD is 100 : 10.

Induced daldinin A, B, C with a new skeleton from cultures of the ascomycete Daldinia concentrica.

Daldinin A, B, C with a new skeleton, together with four known compounds, were induced and isolated from cultures of the ascomycete Daldinia concentrica. Their structures were elucidated by spectroscopic analysis, and that of daldinin A was confirmed by single-crystal X-ray diffraction.

Six new induced sesquiterpenes from the cultures of ascomycete Daldinia concentrica.

Six new sesquiterpenes having the botryane carbon skeleton (1-6), together with known compounds (7-10) were induced and isolated from the ascomycete Daldinia concentrica (strain S 0318). Structures elucidation was accomplished by NMR spectroscopic and X-ray crystallographic studies.

New phenyl-ethanediols from the culture broth of Boletus edulis.

A new phenyl-ethanediol, (1S)-(4-acetylphenyl)-1, 2-ethanediol (1), and a new natural product, (1S)-(3-ethenylphenyl)-1, 2-ethanediol (2), were isolated from the culture broth of the basidiomycete Boletus edulis together with three related known compounds, 1-(4-ethylphenyl)-1, 2-ethanediol (3), 1-(3-ethylphenyl)-1, 2-ethanediol (4) and 1-(3-formylphenyl)-ethanone (5). Their structures were elucidated by spectroscopic methods including extensive 2D-NMR techniques.

Reaction of 5-40 eV ions with self-assembled monolayers.

The reaction of 5-40 eV O(+) and Ne(+) ions with alkanethiolate and semifluorinated alkanethiolate self-assembled monolayers (SAMs) is studied under ultrahigh vacuum (UHV) conditions. Whereas Ne(+) simply sputters fragments from the surface, O(+) can also abstract surface atoms and break C-C bonds in both the hydrocarbon and fluorocarbon SAM chains. Isotopic labeling experiments reveal that O(+) initially abstracts hydrogen atoms from the outermost two carbon atoms on an alkanethiolate SAM chain. However, the position of the isotopic label quickly becomes scrambled along the chain as the SAM is damaged through continuous ion bombardment. Scanning tunneling microscopy (STM) monitors changes in the SAM conformational structure at various stages during 5 eV ion bombardment. STM images indicate that O(+) reacts less efficiently with dodecanethiolate molecules packed internally within a structural domain than it does with molecules adsorbed at domain boundaries or near defect sites. STM images recorded after Ne(+) bombardment suggest that Ne(+) attacks the SAM exclusively near the domain boundaries. Taken collectively, these experiments advance our understanding of the degradation pathways suffered by polymeric satellite materials in the low-earth orbit (LEO) space environment.

Natural aromatic steroids as potential molecular fossils from the fruiting bodies of the ascomycete Daldinia concentrica.

The identification of aromatic steroid hydrocarbons bearing a methyl group at positions 1, 2, 3, 4, or 6 in sediments and petroleum has been puzzling since possible steroidal precursors have not yet been reported in living organisms. Two new aromatic steroids, (17beta,20R,22E,24R)-19-norergosta-1,3,5,7,9,14,22-heptaene (1) and (17beta,20R,22E,24R)-1-methyl-19-norergosta-1,3,5,7,9,14,22-heptaene (2), were isolated from the ascomycete Daldinia concentrica, of which compound 2 bears an unusual methyl group at position 1. We propose that the origin of these compounds is derived from the transformation undergone by their precursor due to microbial action. Compounds 1 and 2 could be the long-sought, biological precursor steroids for organic matter in Earth's subsurface.

Site-selective abstraction in the reaction of 5-20 eV O+ with a self-assembled monolayer.

Site-specific reaction of hyperthermal O+ with a self-assembled monolayer is described. Isotopic labeling experiments reveal the percentage of abstraction products formed from hydrogen atoms bound originally to the top three carbon atoms in the chain.