Membrane Surface-Enhanced Raman Spectroscopy for Cholesterol-Modified Lipid Systems: Effect of Gold Nanoparticle Size.

A gold nanoparticle (AuNP) has a localized surface plasmon resonance peak depending on its size, which is often utilized for surface-enhanced Raman scattering (SERS). To obtain information on the cholesterol (Chol)-incorporated lipid membranes by SERS, AuNPs (5, 100 nm) were first functionalized by 1-octanethiol and then modified by lipids (AuNP@lipid). In membrane surface-enhanced Raman spectroscopy (MSERS), both signals from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and Chol molecules were enhanced, depending on preparation conditions (size of AuNPs and lipid/AuNP ratio). The enhancement factors (EFs) were calculated to estimate the efficiency of AuNPs on Raman enhancement. The size of AuNP100nm@lipid was 152.0 ± 12.8 nm, which showed an surface enhancement Raman spectrum with an EF2850 value of 111 ± 9. The size of AuNP5nm@lipid prepared with a lipid/AuNP ratio of 1.38 × 104 (lipid molecule/particle) was 275.3 ± 20.2 nm, which showed the highest enhancement with an EF2850 value of 131 ± 21. On the basis of fluorescent probe analyses, the membrane fluidity and polarity of AuNP@lipid were almost similar to DOPC/Chol liposome, indicating an intact membrane of DOPC/Chol after modification with AuNPs. Finally, the membrane properties of AuNP@lipid systems were also discussed on the basis of the obtained MSERS signals.

Green fabrication of biologically active magnetic core-shell Fe3O4/Au nanoparticles and their potential anticancer effect.

Core-shell Fe3O4/Au nanostructures were constructed using an advanced method of two-step synthesis from Juglans regia (walnut) green husk extract. Several complementary methods were applied to investigate structural and magnetic properties of the samples. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), electron diffraction, optical, thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) were used for nanoparticle characterizations. As shown by HR-TEM, the mean diameter of core-shell Fe3O4/Au nanoparticles synthesized using co-precipitation method was 6.08 ±â€¯1.06 nm. This study shows that the physical and structural properties of core-shell Fe3O4/Au nanoparticles possess intrinsic properties of gold and magnetite. VSM revealed that the core-shell Fe3O4/Au have high saturation magnetization and low coercivity due to the magnetic properties. The core-shell nanoparticles show the inhibitory concentration (IC)50 of 235 µg/ml against a colorectal cancer cell line, HT-29. When tested against non-cancer cells, IC50 was not achieved even up to 500 µg/ml. This study highlights the magnetic properties and anticancer action of core-shell Fe3O4/Au nanoparticles. This compound can be ideal candidate for cancer treatment and other biomedical applications.

Self-assembled heteropolyacid on nitrogen-enriched carbon nanofiber for vanadium flow batteries.

A novel polyoxometalate-based electrode was developed by incorporating phosphotungstic acid (PWA) in nylon-6,6 nanofiber, followed by carbonization. The developed PWA-carbon nanofiber (PWA-CNF) showed the characteristics of the dual-scale porosity of micro- and mesoporous substrate with surface area of around 684 m2 g-1. The compound exhibited excellent stability in vanadium electrolyte and battery cycling. Evaluation of electrocatalytic properties toward V2+/V3+ and VO2+/VO2+ redox couples indicated promising advantages in electron transfer kinetics and increasing energy efficiency, particularly for the VO2+/VO2+ couple. Moreover, the developed electrode exhibited substantially improved energy efficiency (14% higher than that of pristine carbon felt) in the single cell vanadium redox flow battery. This outstanding performance was attributed to high surface area and abundant oxygen-containing linkages in the developed electrode.

Evaluation of Alkylamine Modified Pt Nanoparticles as Oxygen Reduction Reaction Electrocatalyst for Fuel Cells via Electrochemical Impedance Spectroscopy.

Organically (octyl amine, OA) surface modified electrocatalyst (OA-Pt/CB) was studied for its oxygen reduction reaction (ORR) activity via dc methods and its charge and mass transfer properties were studied via electrochemical impedance spectroscopy (EIS). Comparison with a commercial catalyst (TEC10V30E) with similar Pt content was also carried out. In EIS, both the catalysts showed a single time-constant with an emerging high-frequency semicircle of very small diameter which was fitted using suitable equivalent circuits. The organically modified catalyst showed lower charge-transfer resistance and hence, low polarization resistance in high potential region as compared to the commercial catalyst. The dominance of kinetic processes was observed at 0.925-1.000 V, whereas domination of diffusion based processes was observed at lower potential region for the organic catalyst. No effect due to the presence of carbon was observed in the EIS spectra. Using the hydrodynamic method, higher current penetration depth was obtained for the organically modified catalyst at 1600 rpm. Exchange current density and Tafel slopes for both the electrocatalysts were calculated from the polarization resistance obtained from EIS which was in correlation with the results obtained from dc methods.

In Silico and In Vitro Study of the Bromelain-Phytochemical Complex Inhibition of Phospholipase A2 (Pla2).

Phospholipase A2 (Pla2) is an enzyme that induces inflammation, making Pla2 activity an effective approach to reduce inflammation. Therefore, investigating natural compounds for this Pla2 inhibitory activity has important therapeutic potential. The objective of this study was to investigate the potential in bromelain-phytochemical complex inhibitors via a combination of in silico and in vitro methods. Bromelain-amenthoflavone displays antagonistic effects on Pla2. Bromelian-asiaticoside and bromelain-diosgenin displayed synergistic effects at high concentrations of the combined compounds, with inhibition percentages of more than 70% and 90%, respectively, and antagonistic effects at low concentrations. The synergistic effect of the bromelain-asiaticoside and bromelain-diosgenin combinations represents a new application in treating inflammation. These findings not only provide significant quantitative data, but also provide an insight on valuable implications for the combined use of bromelain with asiaticoside and diosgenin in treating inflammation, and may help researchers develop more natural bioactive compounds in daily foods as anti-inflammatory agent.

Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed (Kappaphycus alvarezii) Extract.

In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii (K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm(-1), which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm.

Platinum nanoparticles modified with alkylamine derivatives as an active and stable catalyst for oxygen reduction reaction.

Platinum nanoparticles (NPs) protected with octylamine (OA) as well as partially replaced by controlled ratios of alkylamine with pyrene group (PA) were successfully synthesized by a two-phase liquid reduction method of Pt(IV). The NPs without any pretreatment to remove the introduced organic-protected agents have been well-characterized and applied as supported catalysts on carbon black for oxygen reduction reaction (ORR). The modification of the Pt NP surface with OA and PA significantly improved the electrocatalytic activity such as area specific and mass specific activities, whose values increased by an increase in PA ratios. The potential cycle test demonstrates that the PA modification of Pt NPs enhances the stability of the catalyst and sustains high area and mass specific activities of ORR.

Oligomerization of cadmium chalcogenide nanocrystals into CdTe-containing superlattice chains.

Hierarchically-assembled binary cadmium chalcogenide (CdX, X = S, Se, Te) oligomers were engineered. CdTe precursor injections into a solution containing seeded nanocrystals provided longer oligomers possessing alternating and phase-separated CdX and CdTe constituents in the same wire, like an alternating copolymer.

Fabrication of a tubular FeCo bimetallic nanostructure using a cellulose-cobalt hexacyanoferrate composite as a precursor.

A tubular fibre structure with a ca. 9-11 microm outer diameter comprised of FeCo nanoparticle assemblies with an amorphous carbon core was fabricated via reductive thermal decomposition of a cellulose-cobalt hexacyanoferrate (Fe-CN-Co) composite material.

Control of stripelike and hexagonal self-assembly of gold nanoparticles by the tuning of interactions between triphenylene ligands.

We describe the self-assembly of gold nanoparticles (Au NPs) protected with newly synthesized discotic liquid crystalline molecules of hexaalkoxy-substituted triphenylene (TP) in mixed toluene/methanol solvent. The stripelike (i.e., 2D consisting of linear 1D in stripe) self-assembly is realized successfully by the aid of pi-pi stacking of TP ligand on Au NPs. The smaller Au NPs with TP (AuTP) or the longer alkyl chain between TP and the gold core provide more free spaces among TP moieties. These spaces allow easy insertion of TP on adjacent AuTPs to lead an interparticle pi-pi interaction to form the stripelike arrangement. The solvent hydrophilicity can also serve as a controlled index to tune arrangement among stripelike, hexagonal close packed (hcp), or disorder. We have changed the solvent hydrophilicity by changing the ratio of methanol to toluene, which affects the balance of solution of AuTP (in toluene) and deposition (in methanol). The larger space between TPs and appropriate solvent hydrophilicity realize stripelike self-assembly caused by a strong pi-pi interaction between TPs, which was characterized by TEM, as well as fluorescence, dynamic light scattering, and 1H NMR spectra.

Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles.

Nanometer-size metal coordination polymers are fascinating to explore, since their unique properties are controlled by a large ratio of surface atoms, which is an entirely different effect from that in a bulk crystal. In this report, we have demonstrated the reaction time-induced structural conversion of nanometer-sized metal coordination nano-polymers (MCNPs). The MCNP selected here was a Prussian blue analogue, cobalt hexacyanoferrate (Fe-CN-Co) with ca. 3 nm. When Fe-CN-Co MCNPs were synthesized in reverse micelles of cationic surfactants, cetyltrimethylammonium halides [CTAX, X=B (bromide), C (chloride)], their color dramatically changed from red to green with increasing the reaction time. We investigated the mechanism of this characteristic color change using XRD, FT-IR, UV-vis spectra, CHN elemental analyses, ICP, and TGA, which indicated that the coordination geometry of Co(II) ions was changed from a 6-coordinate octahedral (Oh) to a 4-coordinate tetrahedral (Td) with clear crystal distortion. The magnetic behavior of the prepared Fe-CN-Co MCNPs was also reaction-time dependent, as illustrated by SQUID and 57Fe Mössbauer spectra.

Preparation of single-crystalline platinum nanowires with small diameters under mild conditions.

We report a convenient method to synthesize single-crystalline platinum nanowires with high aspect ratio of ca. 2.0 nm diameter by sophisticated and precise control of Pt(0) nuclei and their growth.

Self-assembly of discotic liquid crystalline molecule-modified gold nanoparticles: control of 1D and hexagonal ordering induced by solvent polarity.

Gold nanoparticles fully coated with discotic liquid crystalline molecules of hexaalkoxy-substituted triphenylene (Au-TP) have been synthesised, the self-assembled structure of which could be controlled (hexagonal or 1D nanochain) just by altering the ratio of methanol to toluene in the solvent.

[A paclitaxel-resistant case of recurrent breast cancer responded to combination therapy of capecitabine and trastuzumab].

The patient was a 72-year-old female. Under the supervision of her former doctor, this patient had an operation and adjuvant chemotherapy for progressive breast cancer. During the following period, local recurrence of breast cancer and pulmonary lymphopathia developed. Although medication with paclitaxel was attempted, the focus was resistant to this treatment, and metastasis to the brain was also observed. Due to the dyscrasia above, the patient had difficulty breathing and became bedridden. Subsequently, combination treatment of capecitabine and trastuzumab was attempted. As a result,metastasis in the brain and pulmonary lymphopathia were improved. The patient recovered enough to be discharged at one time. However, his condition took a turn for the worse after the interruption of the combination treatment by a side effect. In conclusion, the combination treatment of capecitabine and trastuzumab is thought to be effective for non-responders to paclitaxel.

Novel synthetic approach to creating PtCo alloy nanoparticles by reduction of metal coordination nano-polymers.

PtCo alloy nanoparticles with different metal elemental ratios (Pt/Co = 0.9, 1.6, 2.9, and 3.6) were prepared by a novel synthetic approach, using the transformation reaction of platinum(IV)/cobalt tetracyanoplatinate metal coordination nano-polymers (Pt(II)-CN-Pt(IV)/Co)via a H2 gas-phase reduction.

Synthesis and isolation of cobalt hexacyanoferrate/chromate metal coordination nanopolymers stabilized by alkylamino ligand with metal elemental control.

This Communication describes the novel isolation with metal elemental control of cobalt hexacyanoferrate/chromate metal coordination polymers, stabilized by stearylamine (Co-Fe/Cr-SA) as a protecting coordination ligand in a reverse micelle technique. Each Co-Fe/Cr-SA can be isolated with high uniformity of particle size and elemental composition, and the ratio of the metal component depends on the fundamental characteristics of Co-Fe/Cr-SA: the nanopolymer's shape, color, and magnetism.

Planar array of 1D gold nanoparticles on ridge-and-valley structured carbon.

For fabrication of a planar array of 1D chains of gold nanoparticles prepared by a chemical process, the faceted (110) planes of sodium chloride crystals were used as templates to produce nanoscale ridge-and-valley structured carbon layers by a vacuum process. When these carbon layers loaded on copper grids were dipped in toluene solution of 3.4 nm gold nanoparticles followed by natural dry, a planar array of 1D chains of gold nanoparticles were formed on carbon layers, where the nanoparticles were immobilized predominantly in valleys and partly on ridges of carbon layers.