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Herein we propose a hybridization chain reaction based kinetics competition strategy able to recognize the combination/sequence of input signals. Further, a DNA priority encoder and a keypad lock were constructed. This strategy allowed us to develop a one-pot assay that can automatically and smartly respond to multiple inputs. [ABSTRACT FROM AUTHOR]

We report the design of a high-performance asymmetric supercapacitor (ASC) based on manganese monoxide/carbon aerogel (MnO/NCA) composites as the positive electrode and iron oxide/carbon aerogel (Fe2O3/NCA) composites as the negative electrode. The prepared MnO/NCA hybrid composites display a highly interconnected network structure with ultrathin MnO nanoparticles uniformly embedded into the 3D nitrogen-doped carbon matrix. Because of the synergistic effects of the highly conductive carbon aerogel and highly pseudocapacitive metal oxides, the hybrid MnO/NCA electrode exhibits highly effective surface area, greatly enhanced ion transportation, and excellent electrochemical performance, in comparison with other MnOx-based electrode materials. Matching it with the Fe2O3/NCA cathode, the novel ASC devices can achieve a high voltage window of 2.0 V, delivering a remarkable energy density of 48.67 W h kg−1 at a power density of 1000 W kg−1 and still retains 27.39 W h kg−1 at a high power density of 10 kW kg−1, consequently giving rise to stable cycling performance. These encouraging results will provide a fresh route for the design and fabrication of metal oxide@carbon aerogel materials for application in next-generation storage systems. [ABSTRACT FROM AUTHOR]

Nitrites (NO2− ions) in food and drink play an important role in human health but require complicated operations before detection. Herein, we present a rationally designed SERS-enabled micro-chamber that comprised a drawn glass capillary with a tiny orifice (∼50 μm) at the distal tip, wherein the gold nanoparticles (Au NPs) are compactly coated on the inner wall surface. In this chamber, nitrites specifically trigger a pH and laser irradiance-dependent diazotization starting from p-aminothiophenol (PATP) absorbed onto the surface of Au NPs to form p,p′-dimercaptoazobenzene (DMAB) molecules, in which the presence of NO2− ions above 30.7 μM (1.38 ppm) in the siphoned liquid sample can be identified relying on SERS peak (1141 cm−1) intensity of the emerging azo moiety. Except for pH conditions, laser irradiance is more important but easily neglected in previous studies, which is capable of preventing generation of errors when the detection sensitivity was pursued through increasing the laser power. In this case, several real samples (rather than simple water samples), including honey, pickled vegetable and fermented bean curd, had been successfully detected accurately through such a convenient sampling micro-chamber. The SERS-enabled device could potentially be facilely incorporated with portable Raman instruments for a special application of food inspection in rapid and field analysis of NO2− ions. [ABSTRACT FROM AUTHOR]

We report on a continuous and non-invasive approach in vivo to monitor arterial blood pH based on the laser trapping and Raman detection of single live erythrocytes. A home-built confocal laser tweezers Raman system (LTRS) is applied to trace the live erythrocytes at different pH values of the extracellular environment to record their corresponding Raman changes in vitro and in vivo. The analysis results in vitro show that when the extracellular environment pH changes from 6.5 to 9.0, the Raman intensity ratio (R1603, 1616 = I1603/I1616) of single erythrocytes decrease regularly; what is more, there is a good linear relationship between these two variables, and the linearity is 0.985, which is also verified successfully via in vivo Raman measurements. These results demonstrate that the Raman signal of single live erythrocytes is possible as a marker of the extracellular pH value. This in vivo and quantitative Raman-pH sensor of arterial blood will be an important candidate for monitoring the acid–base status during the treatment of ill patients and in some major surgeries because of its continuous and non-invasive characters. [ABSTRACT FROM AUTHOR]

Anisotropic metallic nanoparticles (NPs) possess unique optical properties, which lend them to applications such as surface-enhanced Raman scattering (SERS). However, their preparation by an efficient, biocompatible and high yield synthetic method is still challenging. In this work, we demonstrate a simple and reproducible way to produce chitosan (CS) encapsulated gold–silver nanoflowers by sequentially adding chitosan, chloroauric acid, silver nitrate, and ascorbic acid to water at room temperature. This is a one-pot, seed- and surfactant-free synthetic method, which is simple and credible. CS is used to modulate the size of NPs, while AgNO3 is introduced to improve the monodispersity and homogeneity of NPs. Highly sensitive, spectrally and physically stable SERS tags are developed in virtue of the cooperative effect of CS and Ag+. Cresyl violet (CV) is applied as a Raman reporter to test the SERS property of NPs, and the results demonstrated that the nanoflowers exhibited stronger and more stable SERS signals than those of spherical gold nanoparticles. Importantly, after being modified by tumor cell-specific targeting ligands (folic acid), the sensitive and stable labeled nanoflowers are applied for cancer cell targeting and SERS imaging. [ABSTRACT FROM AUTHOR]

The precisely controlled synthesis of a specific morphology is proved to be highly effective for enhancing sensing performance of functional micro- and nano-materials. Thus, a comprehensive understanding of the effect of synthesis conditions on morphology evolution is of great importance. In this paper, by using In2O3 as an example, we demonstrate the great effect of supersaturation on the morphology evolution during the growth process. Under vapour-phase synthesis, by varying positions of product collection, the amount of the starting materials, and reaction temperatures, a continuous two-step route consisting of ammonolysis and re-oxidation processes was developed for the morphology evolution of several kinds of In2O3, including octahedron strings, nanowires, crystal chains, lollipop-like structures, and particles. The controlled supersaturation of the In2O3 vapour was eventually proved to be a decisive factor for the formation of various In2O3 morphologies. Furthermore, we evaluated the gas-sensing properties of the three kinds of one-pot synthesized In2O3, indicating a shape-dependent relationship with sensing performance. The present work not only offers a unique strategy to control supersaturation in vapour-phase synthesis, but also provides an opportunity to deeply understand the morphology-dependent sensing performance. [ABSTRACT FROM AUTHOR]

Novel three-dimensional (3D) nano-assemblies of noble metal nanoparticle (NP)–infinite coordination polymers (ICPs) are conveniently fabricated through the infiltration of HAuCl4 into hollow Au@Ag@ICPs core–shell nanostructures and its replacement reaction with Au@Ag NPs. The present 3D nano-assemblies exhibit highly efficient and specific intrinsic oxidase-like activity even without adding any cosubstrate. [ABSTRACT FROM AUTHOR]

We report a new and efficient protocol for rapid electrodeposition of a gold–Prussian blue ((Au–PB)REd) nanocomposite with ultrahigh electroactivity on an Au electrode by cyclic voltammetry in 0.1 M aqueous K2SO4 containing 1 mM K3Fe(CN)6, 1 mM HAuCl4, and 0.1 mM Fe2(SO4)3, and an electrochemical quartz crystal microbalance and scanning electron microscopy were utilized to investigate the electrodeposition. The (Au–PB)REd/Au electrode was then cast-coated with a urate oxidase (UOx)–poly(anilineboronic acid) (PABA)–Pt nanoparticle (PtNP) bionanocomposite and chitosan (CS) for high-performance amperometric biosensing of uric acid (UA) in the dual-potential mode. The UOx–PABA–PtNP bionanocomposite was prepared through chemical oxidation of anilineboronic acid (ABA) by sodium chloroplatinate in the presence of UOx. The thus-fabricated CS/UOx–PABA–PtNP/(Au–PB)REd/Au enzyme electrode worked well under optimized conditions through both oxidation and reduction determination of enzyme-generated H2O2, which responded linearly to UA concentrations from 0.3 μM to 0.65 mM with a sensitivity of 223 μA mM−1 cm−2 and a limit of detection (LOD) of 0.2 μM (0.7 V vs. SCE), and from 0.2 μM to 0.25 mM with a sensitivity of 247 μA mM−1 cm−2 and a LOD of 0.1 μM (−0.05 V vs. SCE), being superior to most analogues hitherto reported for biosensing of UA. [ABSTRACT FROM AUTHOR]

We describe a highly sensitive and spectrally stable surface-enhanced Raman scattering (SERS) tag for live cell imaging based on carbon-encapsulated gold nano-aggregates (CEGNAs). Our findings reveal that controlling the synthesis of the gold nano-aggregate core can be achieved under the mediation of cetyltrimethylammonium bromide (CTAB) through electrostatic forces and hydrophobic interactions, and as the number of particles in the aggregates increase, the relative SERS activity also increases hugely. [ABSTRACT FROM AUTHOR]

A simple method of fabricating shape-tunable Au nanopeanuts from Au–Ag core–shell nanoparticles based on both galvanic replacement and reagent reduction is described. [ABSTRACT FROM AUTHOR]

A label-free optical probe was developed for Ca(2+) detection based on the aggregation-induced emission property of Au(i)-thiolate complexes. Upon incubation with Ca(2+), the Au(I)-cysteine complexes rapidly aggregated through Cys-Ca(2+) interaction, resulting in a luminescent emission of the complexes. The label-free probe was low cost, simple in design and fast in response.

A simple, toehold-mediated two-way input DNA machine has been developed. Utilizing symmetric and asymmetric protector sequences, INH, XOR logic gates and a half-subtractor are designed based on this two-way structure.

A simple, rapid colorimetry for DNA detection based on non-aggregated gold nanoparticles and magnetic beads has been developed with high selectivity and sensitivity., (This journal is © The Royal Society of Chemistry 2012)

Laser-based refractive index detection, based upon refractive index changes in micro-channels, is a kind of laser-based optical determination for solutions. As it is capable of label-free determination, it has been regarded as a considerable growth prospect. The key aspect in related researches lay in the development of novel detection configurations, which would possibly result in better sensitivity. Over the past decade, micro-channel laser-based refractive index detection has been significantly improved, resulting in traversed, hologram-based, back-scattered, retro-reflected interference, optical ring resonant, etc., detection configurations. Moreover, laser-based refractive index detection has been combined with other laser-based detection strategies, in order to pursue a universal and sensitive detection. And last but not least, some utilizations of laser-based refractive index detection have been reported, while both advantages and drawbacks exist. In this paper, laser-based refractive index detection for micro-channels will be reviewed in proceeding sequence.