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AgGaS2 (AGS) nanocrystals that exist in the orthorhombic phase were successfully prepared for the first time through a one-pot colloidal synthetic strategy using suitable coordinating solvents. These orthorhombic AGS nanocrystals were found to display great potential in visible-light-driven photocatalysis. [ABSTRACT FROM AUTHOR]

The ability of nanoscopic materials to self-organize into large-scale assembly structures that exhibit unique collective properties has opened up new and exciting opportunities in the field of nanotechnology. Although earlier work on nanoscale self-assembly has focused on colloidal spherical nanocrystals as building blocks, there has been significant interest in recent years in the self-assembly of colloidal nanocrystals having well-defined facets or anisotropic shapes. In this review, particular attention is drawn to anisotropic one-dimensional (1D) nanocrystals, notably nanorods and nanowires, which can be arranged into a multitude of higher-order assembly structures. Different strategies have been developed to realize self-assembly of colloidal 1D nanocrystals and these are highlighted in the first part of this review. Self-assembly can take place (1) on substrates through evaporation control, external field facilitation and template use; (2) at interfaces, such as the liquid--liquid and the gas--liquid interface; and (3) in solutions via chemical bonding, depletion attraction forces and linker-mediated interactions. The choice of a self-assembly approach is pivotal to achieving the desired assembly configuration with properties that can be exploited for functional device applications. In the subsequent sections, the various assembly structures that have been created through 1D nanocrystal self-assembly are presented. These organized structures are broadly categorized into non-close-packed and closepacked configurations, and are further classified based on the different types of 1D nanocrystal alignment (side-by-side and end-to-end), orientation (horizontal and vertical) and ordering (nematic and smectic), and depending on the dimensionality of the structure (2D and 3D). The conditions under which different types of arrangements are achieved are also discussed. [ABSTRACT FROM AUTHOR]

In this study, we employ a range of analytical tools to study the interactions between a mixed base peptide nucleic acid (PNA, 22-mer) probe and gold nanoparticles (AuNP). The binding of charge neutral PNA to citrate capped AuNP (50 nm) causes the particles to change size and/or aggregation/dispersion status in a PNA concentration-dependent manner. Under a UV-vis spectrophotometer, AuNP aggregation can be detected at PNA concentrations as high as 400 nm. Using dynamic light scattering measurement, the changing of particle sizes can be detected at a relatively low PNA concentration of 50 nm. Using a resistive pulse sensor, i.e. nanopore-based sensing platform, a particle-by-particle measurement technique, subtle changes of the AuNP size induced by PNA at very low concentrations of 5 nm can be identified. Transmission electron microscopy measurement confirmed that at very low PNA concentration, a small population of particles form a nano-assembly of NP clusters. Based on the fact that hybridization of PNA probe with target DNA is able to retard particle aggregation, we can quantify specific DNA sequences with a limit of detection ranging from 10 nm to 1 nm, depending on the characterization tools used. With this study, we show that as a complementary technique, the resistive pulse nanopore-based sensing platform provides significant resolution advantages for metal nanoparticle measurement as compared with light-based techniques. [ABSTRACT FROM AUTHOR]

A facile method for the fabrication of Quantum Dot/poly(N-isopropylacrylamide) (QD/PNIPAM) micropatterns on glass is presented. Water-soluble QDs functionalized with polymerizable methacrylic groups effectively copolymerize with N-isopropylacrylamide monomer resulting in stable hybrid organic–inorganic networks. The patterns display temperature and pH responsive luminescence behaviour. [ABSTRACT FROM AUTHOR]

A series of porous CaCO3/HA composites have been produced with an increased molar percentage of HA from 0, 10, 25, 50, 75 to 100%. The compression strength of the CaCO3/HA composites increases proportionally before reaching 50% and gradually levels off with a further increase up to 100%. The 50% CaCO3/HA composite, with a similar compression strength to natural bone, has been evaluated in vitroand in vivo, showing great potential for osteoregenerative applications. A three-step chemical process for preparing the CaCO3/HA composites has been revealed by time-dependent XRD analysis: (i) CaCO3→ CaO + CO2↑, (ii) 10CaO + 6(NH4)2HPO4→ Ca10(PO4)6(OH)2+ 12NH3↑ + 8H2O↑, and (iii) CaO + CO2→ CaCO3/Ca(OH)2+ CO2→ CaCO3+ H2O. The initial formation of porous CaO by a fast release of CO2at high temperature leads to the production of the porous CaCO3/HA composites. Such understanding may allow us to extend this solid-phase fabrication approach to various other porous composites with controlled compositions for promising applications. [ABSTRACT FROM AUTHOR]

Oxidation-induced constituent separation of ternary Fe/CoO nanocrystals has been investigated to evidence their exchange bias mechanism, which is important for conceptually new design, synthesis and utilization of magnetic nanostructures. [ABSTRACT FROM AUTHOR]

This paper demonstrates an optimized fabrication of amorphous Ru nanoparticles through annealing at various temperatures ranging from 150 to 700 °C, which are used as water oxidation catalyst for effective electrochemical water splitting under a low overpotential of less than 300 mV. The amorphous Ru nanoparticles with short-range ordered structure exhibit an optimal and stable electrocatalytic activity after annealing at 250 °C. Interestingly, a small quantity of such Ru nanoparticles in a thin film on fluorine-doped tin oxide glass is also effectively driven by a conventional crystalline silicon solar cell that has excellent capability for harvesting visible light. Remarkably, it achieves an overall solar-to-hydrogen efficiency of 11.3% in acidic electrolyte. [ABSTRACT FROM AUTHOR]