Developments in subcellular fractionation strategies have provided the means to analyze the protein and lipid composition of organelles by proteomics. Here, we developed ultrasmall magnetic–plasmonic hybrid nanobeads and applied them to the isolation of autophagosomes by applying a magnetic field. The beads were chemically synthesized and comprised an Ag/FeCo/Ag core/shell/shell structure with a mean diameter of 15 nm. The Ag core and the FeCo shell conferred imaging and magnetic separation capabilities, respectively. The nanobeads were transfected into mammalian cells by lipofection. Thirty minutes after lipofection, the nanobeads colocalized with Vps26 and subsequently with LC3. Cell lysates were prepared at the appropriate time points and were subjected to magnetic separation. The separated fraction contained LC3-II, transferrin receptor, and LAMP2, but not LC3-I, suggesting that autophagosomes engulfing endosomal origin had been isolated. The magnetic separation process was completed in less than 30 min, providing a rapid method for isolation of autophagosomes. The present organelle isolation technique using the hybrid nanobeads with imaging and magnetic separation capabilities is highly promising for isolation of other types of organelles such as endosomes and endosome-related organelles.Topics: Biocompatible materials; Biocompatible materials; Biological imaging; Cell and Molecular biology; Distribution function; Hydrogen; Hydrogen; Magnetic processes; Molecular structure; Nanofabrication; Nanostructures; Surface structure; Surface treatment;

Nanoparticles with nominal structures of Au@Ag (core@shell) and Au@Ag@Au (core@shell@shell) were prepared using the sequential citrate reduction technique and characterized using routine characterization techniques, including transmission electron microscopy. X-ray absorption spectroscopy was then carried out on the samples, and extended X-ray absorption fine structure (EXAFS) analysis was used to determine the structure of the systems. The results of the routine techniques and the X-ray absorption spectroscopy were then compared. EXAFS analysis of the nanoparticles with the Au@Ag structure revealed very limited bimetallic interactions, supporting the assignment of a core@shell structure. EXAFS analysis of the nanoparticles with Au@Ag@Au structure showed an increased proportion of bimetallic interactions. Based on the colloid composition, the other characterization techniques and the chemistry of the system, these nanoparticles were interpreted as having an Au@Au/Ag-alloy structure. The EXAFS analyses corroborated the other characterization techniques and enabled the determination of the average-structure of the entire sample.

A heterostructured copper sulfide–zinc sulfide nanocomposite is explored as a new class of low temperature and sustainable thermoelectric materials. The nanoparticles are created through a wet chemical synthetic technique and display a remarkable Janus structure. These nanoparticles are processed as building blocks by molecular linking with short alkyl chain ligands to enhance their electrical conductivity. The nanomaterials are pressed into a pellet and subjected to subsequent thermal annealing to remove volatiles and enhance particle contacts through sintering. The resulting nanocomposite materials were characterized to assess the thermoelectric characteristics, revealing P-type conductivity.

Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-l-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

This report describes findings of an investigation of harvesting nanocatalytic heat localized in a nanoalloy catalyst layer as a heat source in a nanocomposite thin film thermoelectric device for thermoelectric energy conversion. This device couples a heterostructured copper–zinc sulfide nanocomposite for thermoelectrics and low-temperature combustion of methanol fuels over a platinum–cobalt nanoalloy catalyst for producing heat localized in the nanocatalyst layer. The possibility of tuning nanocatalytic heat in the nanocatalyst and thin film thermoelectric properties by compositions points to a promising pathway in thermoelectric energy conversion.

We report a new ligand directed chemical synthesis of hexagonal shaped zinc nanoplates. The produced nano-hexagons (NHexs) display a thickness of about 20–40 nm and diameter ranging from about 200–350 nm, exhibiting a high aspect ratio. While zinc is traditionally highly susceptible to oxidation, these high surface area NHexs possess a remarkable resistance to atmospheric oxidation, owing to their unique surface crystalline faces and the fact that these particles are protected by organic surface ligands. The zinc NHexs size, morphology and chemical properties were characterized using transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy, among other techniques. Photoluminescence spectroscopy analysis revealed blue photoluminescence emission, making these NHexs potentially ideal for optics, optoelectronics or security printing.

•We study the SERS activity of FePt@Ag nanoparticles (NPs) under magnetic field.•The SERS activity linearly decreases with increasing the magnetic field strength.•The reduction of SERS activity is more pronounced for FePt@Ag than that for Ag NPs.•The more pronounced effect observed in FePt@Ag is due to the local magnetic field.The surface-enhanced Raman scattering (SERS) activities of Ag and FePt@Ag nanoparticle probes were examined using thiophenol as a Raman reporter molecule in the absence and presence of a magnetic field. Under external magnetic fields of different field strength, the SERS activities of both types of nanoparticles (NPs) were weakened as a function of magnetic field strength. The attenuation degree of SERS activity by the magnetic field in the case of FePt@Ag NPs is found to be two times higher than for Ag NPs, because the superparamagnetic FePt cores enhance the local magnetic field at the area of the Ag shells.

Charge transfer in heteromeric structures such as gold–silver core–shell (Au@Ag) nanoparticles (NPs) and gold–silver–gold double-shell (Au@Ag@Au) NPs was demonstrated using X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) techniques. XANES analyses confirmed that the d-orbital hole density of the Au atoms increases in the following order: Au foil ≅ Au NPs < Au@Ag NPs < Au@Ag@Au NPs. In conjunction with observed positive and negative shifts in the Au 4f and Ag 3d binding energies in XPS spectra of Au@Ag and Au@Ag@Au NPs, we conclude that d electrons are transferred from Au to Ag in the heteromeric NPs due to the charge compensation mechanism. By taking advantage of the charge transfer phenomenon, one can modify the electronic structure of heteromeric NPs with enhanced chemical stability and optical/electronic properties.

Nanocomposite films consisting of gold nanoparticles (Au NPs) and boehmite nanorods (NRs) were synthesized via simple wet chemical methods. The nanocomposite film exhibited an excellent optical sensing capability of humidity utilizing the refractive-index-dependent localized surface plasmon resonance (LSPR), which directly enables low-cost and easy-to-use remote humidity monitoring. It has been revealed that the superior performance of the Au-NP/boehmite nanocomposite film is owing to porousness, smoothness, and hydrophilicity of the boehmite matrix.

The formation mechanism of Ag nanoparticles (NPs) synthesized with a wet-chemical reduction method using sodium acrylate as a dual reducing and capping agent was investigated with various analytical techniques. The time course of the state of the reaction solution was investigated using UV-vis and XAFS spectroscopies which showed that the NP formation rate increased with increasing concentration of sodium hydroxide (NaOH). The detailed kinetic analyses reveal that both the reduction rate of Ag ions and the nucleation rate of Ag NPs are dramatically increased with increasing NaOH concentration. XANES analyses imply that another reaction pathway via alternative Ag+ species, such as Ag(OH)x, was developed in the presence of NaOH. Consequently, NaOH is found to play an important role not only in creating specific intermediates in the reduction of Ag+ to Ag0, but also in accelerating the reduction and nucleation rates by enhancing the oxidation of sodium acrylate, thereby increasing the rate of formation of the Ag NPs.

This paper reports a study on the formation mechanism of nanoparticles (NPs) composed of bismuth, antimony and tellurium for thermoelectric materials using a modified polyol synthetic route. Our one-pot synthesis technique has proven highly versatile in creating a wide range of different anisotropic NPs such as nanowires (NWs), nanodiscs (NDs), nanoribbons and nanospines (NDs studded on NWs) simply by modifying the capping species or elemental precursor feeding ratio used in the synthesis. However, an independent control of morphology and composition is still hugely challenging and the facile synthesis of (Bi,Sb)2Te3 solid solution NPs is not a trivial task, reflecting the complex nature of this multicomponent system. To achieve this goal, it is imperative to understand the formation mechanism based on a systematic investigation of mono- and binary elemental NP systems. Our study clearly shows the different actions of oleylamine (OAM) and decanethiol (DT) capping ligands in our synthesis reaction. In the case of DT capping system, Te NDs are first formed, and then, Bi and Sb are separately incorporated into the Te ND structure viacatalytic decomposition of Bi-DT and Sb-DT complexes on the Te ND surfaces. Therefore, the resulting NPs are phase segregated into Te, Bi2Te3 and Sb2Te3. On the other hand, in the case of the OAM capping system, Te NWs and Bi-Sb solid solution NPs are formed separately, and then, parts of Te NWs are transformed into (Bi,Sb)2Te3 phase via oriented attachment of Bi-Sb NPs and Te NWs. These findings are crucially important towards the one-pot synthesis of uniform (Bi,Sb)2Te3 nanobuilding blocks with controllable characteristics for highly efficient thermoelectric materials.

Magnetic fluorescent FePt@CdSe core–shell nanoparticles were directly synthesized by sequential addition of precursors and using tetraethylene glycol as a solvent and a reducing agent. The core–shell NPs were successfully formed over a wide range of temperature (240–300 °C). The size and composition of the FePt core were tuned by changing the ratio of surfactant (oleic acid and oleylamine) to metal precursors [Fe3(CO)12 and Pt(acac)2] and the feeding ratio of the precursors, respectively. The CdSe shell thickness also could be varied from 1 to 8.5 nm by rational control of the total amount of Cd and Se precursors. FePt@CdSe core–shell NPs with a core size of about 4.3 nm and shell thickness of about 2.5 nm displayed a fluorescence emission around 600 nm. They exhibited superparamagnetic behaviour at room temperature and the blocking temperature was about 55 K, which was almost the same as uncoated FePt NPs, while the coercivity decreased from 400 Oe for the FePt NPs to 200 Oe. Detailed characterization of intermediates and synthesized FePt@CdSe NPs revealed the fine structure and formation mechanism.

We present a new type of nanoparticle-based DNA sensor using surface-enhanced Raman scattering (SERS) on gold nanoparticle (Au NP) aggregates formed by DNA photoligation. The DNA sensor exploits the photoligation reaction between oligodeoxynucleotides (ODNs) attached to the surfaces of Au NPs in the presence of target DNA (T-DNA). When hybridization takes place between the ODNs and T-DNA, Au NPs are covalently crosslinked to form aggregates via photoligation. Once the NP aggregates are formed, the interspace between Au NPs in the aggregate act as a stable “hot spot”, and a SERS signal from the Raman-active molecules (sodium cacodylate) present in the hot spot is easily and sensitively detected. In contrast, a SERS signal is not detected if the hybridization is unsuccessful, because the stable hot spot does not form. This DNA sensor does not require an enzymatic reaction, fluorescent dye, precise temperature control, or complicated operating procedures.

The formation mechanism of copper nanoparticles (NPs) using poly(N-vinyl-2-pyrrolidone) (PVP) as a capping agent was investigated by measurements of X-ray diffraction (XRD), transmission electron microscopy (TEM), in situ time-resolved X-ray adsorption fine structure (XAFS) analysis, in situ UV−vis spectroscopy, and an indicator method. XAFS analyses, in combination with TEM observations and the indicator method, revealed that the stable intermediates such as Cu(OH)2 and Cu+−PVP intermediate were formed during an induction period of nucleation of Cu NPs, which play a critical role in the Cu NP formation. Our results suggest that the PVP capping agent is important not only to protect NPs from overgrowth and aggregation but also to control the reaction kinetics of NP formation.

The formation mechanism of Ag nanoparticles (NPs) synthesized with a wet-chemical reduction method using sodium acrylate as a dual reducing and capping agent was investigated with various analytical techniques. The time course of the state of the reaction solution was investigated using UV-vis and XAFS spectroscopies which showed that the NP formation rate increased with increasing concentration of sodium hydroxide (NaOH). The detailed kinetic analyses reveal that both the reduction rate of Ag ions and the nucleation rate of Ag NPs are dramatically increased with increasing NaOH concentration. XANES analyses imply that another reaction pathway via alternative Ag+ species, such as Ag(OH)x, was developed in the presence of NaOH. Consequently, NaOH is found to play an important role not only in creating specific intermediates in the reduction of Ag+ to Ag0, but also in accelerating the reduction and nucleation rates by enhancing the oxidation of sodium acrylate, thereby increasing the rate of formation of the Ag NPs.