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The arsMgene is a critical biomarker for the potential risk of arsenic exposure in paddy soil. However, on-site screening of arsMis limited by the lack of high-throughput point-of-use (POU) methods. Here, a multiplex CRISPR/Cas12a microfluidic paper-based analytical device (μPAD) was constructed for the high-throughput POU analysis of arsM, with cascade amplification driven by coupling crRNA-enhanced Cas12a and horseradish peroxidase (HRP)-modified probes. First, seven crRNAs were designed to recognize arsM, and their LODs and background signal intensities were evaluated. Next, a step-by-step iterative approach was utilized to develop and optimize coupling systems, which improved the sensitivity 32 times and eliminated background signal interference. Then, ssDNA reporters modified with HRP were introduced to further lower the LOD to 16 fM, and the assay results were visible to the naked eye. A multiplex channel microfluidic paper-based chip was developed for the reaction integration and simultaneous detection of 32 samples and generated a recovery rate between 87.70 and 114.05%, simplifying the pretreatment procedures and achieving high-throughput POU analysis. Finally, arsMin Wanshan paddy soil was screened on site, and the arsMabundance ranged from 1.05 × 106to 6.49 × 107copies/g; this result was not affected by the environmental indicators detected in the study. Thus, a coupling crRNA-based cascade amplification method for analyzing arsMwas constructed, and a microfluidic device was developed that contains many more channels than previous paper chips, greatly improving the analytical performance in paddy soil samples and providing a promising tool for the on-site screening of arsMat large scales.

• Oxy-sulfide inclusions with complex structure of two parts were studied. • Traditional mechanism was not suitable for inclusion-induced localized corrosion. • High dislocation density in matrix around inclusions triggered initiation of pits. • Inclusion-induced localized corrosion would be overwhelmed after longer immersion. The surface properties of weathering steel (WS) is very important for its service performance and safety, and the localized corrosion induced by inclusions is closely related to the surface properties of WS and its application. In the current work, a common spherical (Al, Mg, Ca, Mn)-oxy-sulfide inclusion was selected to investigate the corrosion evolution of complex inclusion and its effect on localized corrosion on WS surface. The results indicate the inclusion in WS consists of (Ca, Mn) sulfides part and (Ca, Al, Mg) oxides part with complex core-shell structure. Locally preferential dissolution occurs in (Ca, Mn) sulfides part as well as metal matrix around the inclusions. Furthermore, both parts of the inclusions with poor conductivity and high-density dislocation at metal matrix around the inclusions was found, which suggests that traditional micro-galvanic corrosion cell may not be the cause of inclusion-induced localized corrosion on WS surface at initial stage of corrosion. The variation in maximum and average depth around the inclusion or selected region with immersion time indicates that localized corrosion induced by inclusions is overwhelmed by uniform corrosion of WS in the latter stage of immersion, then the rust formed on WS surface consists of two layers. [ABSTRACT FROM AUTHOR]

The microstructure and corrosion behavior of Al-Zn-Mg alloy (namely 7×××) after natural aging treatment (NAT) and artificial aging treatment (AAT) in aqueous NaCl solutions containing different aggressive ions have been investigated in current work. Results of microstructure characterization demonstrate that the aging treatment has a great influence on the grain size and precipitates. The grain size is relatively sizeable and no evident precipitates are observed in alloy after NAT comparable with that after AAT. The electrochemical corrosion behavior of alloy was studied by polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion potential (E corr) of the aluminum alloy is more negative in 3.5 wt.% NaCl containing 0.052 wt.% NaHSO 3 solution than that in 3.5 wt.% NaCl solutions with or without 0.907 wt.% NaHCO 3. Charge transfer resistance (R ct) results reveal that alloy after AAT has an enhancement of corrosion resistance compare with that after NAT. With the immersion time increasing, mostly pitting spreads over the surface of the alloy only in NaCl solution, whereas exfoliation corrosion mainly occurs in NaCl solutions containing NaHSO 3 or NaHCO 3. [ABSTRACT FROM AUTHOR]

A reliable and sensitive sensing of multiple foodborne pathogens is critical for timely diagnosis and human health. To meet this need, herein, we designed a sandwich immunoassay platform, using functionalized SERS probes and magnetic beads, for the interference-free simultaneous detection of Escherichia coli(E. coli) and Staphylococcus aureus(S. aureus) in food samples by surface-enhanced Raman scattering (SERS) technology. The signal of two SERS probes coded by triple bonds (CC and CN) located at 2105 and 2227 cm−1, respectively, could perfectly avoid the spectral overlap with coexisting materials in the Raman fingerprint region, which ensured the accuracy of the immunoassay platform. The application of functional magnetic beads, integrating enrichment and separation, greatly improved the sensitivity of the detection system. Under magnetic force, due to the mature interaction between the antigen and antibody, the sandwich immunoassay platform could be fabricated. Its limit of detection (LOD) for the simultaneous detection of E. coliand S. aureuswas as low as 10 and 25 cfu mL−1, respectively, and the sandwich immunoassay platform was successfully applied for the detection of E. coliand S. aureusin bottled water and milk. As a sensitive and highly selective analytical technique for the simultaneous multiple detection of pathogens, this SERS-based method has great potential to be applied in the field of food safety.

Materials with surface wrinkles at a micro/nanoscale possess extraordinary fascinating properties, and various techniques have been employed to create controllable wrinkles. Herein, natural polysaccharide was used to construct the surface wrinkled microsphere with controllable wrinkling patterns. A robust microsphere with an average size of about 55 μm fabricated from chitosan in alkali/urea aqueous solution was swelled and then coated orderly by introducing rigid silver nanoparticles (Ag NPs) with an average size of about 5 nm as the shell onto the surface through electrostatic layer-by-layer (LBL) self-assembly followed by deswelling, resulting in a surface wrinkled microsphere. The significant difference in the swelling behaviors between the stiff Ag shell and swelled chitosan microsphere could generate enough driving forces to form 3D micro- and nanoscale wrinkling surface topography. The surface wrinkled microspheres exhibited the hierarchically porous structure and hydrophobicity, and the topographical patterns could be adjusted by controlling the thickness of the Ag NP layer to achieve the sizes of wrinkling ranging from 60 to 300 nm. It was demonstrated that the wrinkled microspheres were superior as 3D surface-enhanced Raman spectroscopy (SERS) substrates, in which the wrinkled structure with spatial periodicity was proved to be effective for enhancing the SERS signal. The microsphere with controllable wrinkled surface topography could be applied to be a miniature 3D device, which promises potential technological applications in various areas.

Surface-enhanced Raman scattering (SERS) is an important, highly sensitive technique for chemical and biological analysis, which is critically dependent upon high-performance metallic substrates. Anisotropic gold (Au)–silver (Ag) alloy nanoboxes are attractive SERS substrates because of the greatly enhanced Raman signals from the strong electromagnetic fields on the sharp corners. Yet, the routine approach of Au–Ag alloy nanobox synthesis is still challenging because of the complicated procedures and use of biologically/environmentally unfriendly reagents. To facilitate the usage of Au–Ag alloy nanoboxes for broad SERS applications, we propose a facile green strategy to synthesize Au–Ag alloy nanoboxes with superior single-particle SERS sensitivity. Our novel straightforward strategy involves HAuCl4and AgNO3reduction by ascorbic acid, which is achieved in an aqueous one-pot reaction at ambient temperature. Significantly, the surfaces of the prepared Au–Ag alloy nanoboxes are judiciously designed to introduce nanodots, generating numerous “hot spots” for high Raman signal enhancement as indicated by rigorous numerical simulations. By combining scanning electron microscopy and Raman mapping images, we demonstrate the application of Au–Ag alloy nanoboxes for single-particle sensing SERS activity. The as-prepared Au–Ag alloy nanoboxes are expected to facilitate their further applications in quantitative and ultrasensitive SERS detection.

Tips of noble metal nanostructures and the gaps between closely packed noble metal nanostructures are widely claimed as hot-spots for SERS sensing. A significant amount of effort and expertise has been devoted to the reformation and maximum utilization of the “tips” and “gaps”. However, most studies focus on the “tips” or the “gaps” separately. Here we report a novel SERS substrate that contains a particular mesh structure of curved-edge gold nanocubes (CENCs) and Au nanospheres (Au NSs), one of the tips of CENCs inserted into the gaps between three closely packed Au NSs. Meanwhile, a facile and time-saving novel protocol has been proposed to fabricate this mesh structure in the form of a bilayer SERS substrate. The as-fabricated substrate exhibited extraordinary SERS sensitivity for malachite green (MG) and melamine, which could be attributed to the tip–gap mesh structure. The detection limit is as low as 10−12M and 10−9M, respectively.

Field and pretreatment-free detection of heavy-metal ions in organic polluted water is important but still challenging in current water pollution emergency response systems. Here we report a polyadenine–DNA-mediated approach for a rationally designed alkyne-coded surface-enhanced Raman scattering (SERS) test kit, enabling rapid and simultaneous detection of Hg2+and Ag+by a portable spectrometer, impervious to organic interferences. Because of the formation of thymine (T)–Hg2+–T and cytosine (C)–Ag+–C, highly recognizable SERS signals are rapidly detected when two different alkyne-labeled gold nanoparticles (AuNPs) are induced to undergo controllable bridging upon the addition of low-volume targets. For multiplex detection through a portable spectrometer, the limits of detection reach 0.77 and 0.86 nM for Hg2+and Ag+, respectively. Of particular significance, the proposed CC-containing Raman reporters provide an extremely effective solution for multiplex sensing in a spectral silent region, when the hyperspectral and fairly intense optical noises originating from lower wavenumber region (<1800 cm–1) are inevitable under complex ambient conditions.

We herein present a simple and surfactant-free synthetic strategy for the preparation of core–shell Fructus Broussonetia-like Au@Ag@Pt nanoparticles (FBNPs) viaa combination of galvanic replacement and reagent reduction, in which a chitosan (CS)-mediated epitaxial growth of Pt multi-branches occurs on cresyl violet labeled Au core–Ag shell nanoparticles (NPs) at room temperature. The as-prepared novel nanostructures exhibit an enzyme mimetic activity due to the formation of a Fructus Broussonetia-shaped Pt shell, the absence of surfactants and the positively charged CS molecules intertwined within the outermost Pt NPs. Relying on the high sensitivity of resonance-enhanced Raman scattering and the highly efficient intrinsic peroxidase-like activity of FBNPs, H2O2was detected with a wide detection window from 10 pM to 100 μM when utilizing 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate. Based on the H2O2–TMB catalytic oxidation system a simple, sensitive, selective and universal platform has been extended for the detection of all peroxidase-related analytes. For example, glucose at a concentration range of 1 nM to 200 μM was detected in the presence of glucose oxidase with a limit of detection of 1 nM.

Herein, we developed a sensing strategy for the label-free detection of Zn2+based on G-quadruplex. In the absence of Zn2+, there was a fluorescence enhancement of thioflavin T by interaction with human telomere sequence. On the addition of Zn2+, Zn2+induced a more compact G-quadruplex structure to release thioflavin T, resulting in a fluorescence decrease. This simple “mix-then-detect” method gave the detection limit of 0.91 μM with linear dynamic ranges from 0 to 10 μM. Because it does not require the use of expensive and unstable DNAzyme systems, or need synthesis and modification of nanomaterials, this label-free biosensor is simple, fast, cost-effective and applicable for real samples taken from lake water.

By employing two-dimensional and water-soluble graphene oxide (GO), a turn-on sensor was developed for the label-free detection of Zn2+based on Zn2+-induced G-quadruplex (G4) formation. Indicated using the G4-binding ligand thiazole orange (TO), the enhanced fluorescent signal could be generated only when the guanine-rich DNA was excluded from the surface of GO due to the formation of a G4 induced by Zn2+. The results have shown that the method can be utilized for the detection of Zn2+in a linear range from 0–30 μM with a detection limit of 0.71 μM. The real sample testing conducted in serum samples demonstrated its practical potential in biological analysis.

In recent years, considerable efforts have been devoted to the construction of efficient enzyme mimetics, which have significant advantages of simple synthesis and good stability. In this paper, we prepared novel graphene oxide–gold (GO–AuNP) nanohybrids that exhibited fascinating peroxidase-like activity and could catalyze the oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H2O2, while simultaneously developing a blue color in an aqueous solution. Furthermore, single-stranded DNA (ssDNA) were able to resist the salt-induced aggregation of GO–AuNP nanohybrids, whereas double-stranded DNA (dsDNA) did not inhibit salt-induced GO–AuNP nanohybrids aggregation. Based on these unique properties, we developed a label-free colorimetric method for the detection of Hg2+and Pb2+. In the presence of Hg2+or Pb2+, ssDNA formed a hairpin-like or a quadruplex structure, and these conformational changes facilitated the salt-induced aggregation of GO–AuNP nanohybrids, leaving behind a transparent supernatant after centrifugation. After incubation with TMB and H2O2, the colorimetric signal of the centrifugal supernatant was significantly decreased compared to that in the absence of Hg2+or Pb2+. The response to Hg2+and Pb2+were in the range of 0–50 μM. Finally, this simple and sensitive sensor could be successfully applied for the detection of Hg2+and Pb2+in river water.

In this report, we developed an additive-free synthesis of In2O3cubes embedded into graphene networks with InN nanowires (InN-NWs) and graphene oxide (GO) as precursors by a facile one-step microwave-assisted hydrothermal method. In absence of GO, the InN-NWs maintained their chemical composition and original morphology upon the same treatment. At varying mass ratios of InN-NWs and GO, the different morphologies and distributions of In2O3could be obtained on graphene sheets. The uniform distribution, which is usually considered favorable for enhanced sensing performance, was observed in In2O3cubes/reduced graphene oxide (rGO) composites. The room-temperature NO2sensing properties of the In2O3cubes/rGO composites-based sensor were systematically investigated. The results revealed that the sensor exhibited a significant response to NO2gas with a concentration lower to 1 ppm, and an excellent selectivity, even though the concentrations of interferential gases were 1000 times that of NO2. The enhanced NO2sensing performances were attributed to the synergistic effect of uniformly distributed In2O3cubes and graphene sheets in the unique hybrid architectures without the interfering of extra additives.

For the first time, gold nanoclusters were found to exhibit high fluorescence enhancement ability based on the metal-enhanced fluorescence (MEF) effect, which can effectively enhance the fluorescence of fluorescein isothiocyanate (FITC). By means of this phenomenon, Au nanoclusters have been successfully used in the construction of a fluorescence-enhanced sensing platform for the detection of protooncogene.

A recent study reported by Higuchi's group has shown that Pt–DNA complexes possess peroxidase enzymatic activity similar to natural peroxidases. In this study, we prepared Pt–DNA complexes and demonstrated their use in catalyzing the oxidation of a peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2to the oxidized product which provided a colorimetric detection of H2O2. As low as 3.92 × 10−4mol L−1H2O2could be detected with a linear range from 9.79 × 10−4to 1.76 × 10−2mol L−1viaour method. Furthermore, PVDF membranes were employed to increase sensitivity and decrease the detection limit of H2O2, enabling a two-fold improvement in the detection sensitivity as compared with the above counterparts. More importantly, a sensitive and selective method for glucose detection was developed using glucose oxidase (GOx) and the as-prepared Pt–DNA complexes. We realized the test of glucose as low as 10−7mol L−1by the color change, which was comparable to or even better than the existing methods, and identified the concentration of glucose in Sprite with the naked eye without referring to any sophisticated apparatus. The detection platforms for H2O2and glucose developed in the present work showed great potential for applications in the future.

Novel functional oligonucleotides, especially DNAzymes with RNA-cleavage activity, evoke current research interest increasingly due to their potential applications in therapeutics and sensors. One of the most attention-attracting is the lead-specific DNAzyme, which is composed of an enzyme strand 17E and a substrate strand 17S, addition of Pb2+enables the DNAzyme to cleave its substrate. In this study, we took advantage of the unique optical properties of a water-soluble cationic polythiophene (PT) and designed a fluorometric sensing assay for the detection of Pb2+. A simple “mix-and-detect” approach enabled the detection of Pb2+within 20 minutes due to the distinguishable optical properties of PT–dsDNA and PT–ssDNA. As low as 10 nM Pb2+could be detected with a detection range from 10 nM to 100 μM viathis method. Furthermore, this method was highly selective and only minimally perturbed by nonspecific metal ions. Since common steps such as modification and separation could be successfully avoided, this simple, sensitive, specific, and cost-effective approach showed great potential applications in environmental monitoring, waste management and clinical toxicology.

A bi-detection system integrated by laser-induced fluorescence (LIF) and retro-reflected beam interference (RBI) based refractive index was established and applied to simultaneously determine erythrosine and sucrose in candy floss. The system realized separation-free analysis of candy floss without prior concentration steps.

AbstractThe kernel principal component analysis (KPCA) algorithm has been extensively used in target detection and classification for hyperspectral imaging. Kernel parameters are a key component of KPCA, but no optimal method for selecting appropriate parameters has been proposed. We study the largest eigenvalue and sum of the eigenvalues of characteristic equation of kernel matrix, and then put forward a proposal for parameter selection. Experiments show that the proposal enables best parameter selection.

Biological rhythms, which regulate the biological cycles of life, are of great interest in biomedicine. The effect of biological rhythms on bone is controversial at the moment. Raman spectroscopy was applied to assess the bone compositional information of hamsters under different photoperiods, designed as long day photoperiod of 16 h light and 8 h dark (LD, 16L : 8D) and short day photoperiod of 8 h light and 16 h dark (SD, 8L : 16D). After three months under such well-defined conditions, the hamsters in the two groups exhibited differences in body weight, fur color and testis size. In addition, for the first time to our knowledge bone compositional variations were observed in both mineral constituents and collagen secondary structures in hamsters conditioned under the different photoperiods. The collagen secondary structure in the SD hamsters was characterized by a higher ratio of mature intra-fibril cross-links indicating a more stable form of collagen. It is hypothesized that increased bone turnover rate and resorption led to the alteration of collagen cross-links in the SD group.

In order to obtain a deeper insight into the interaction between cytosine and copper electrode, a surface-enhanced Raman scattering (SERS) study and density functional theory (DFT) simulation have been used. The experimental result shows that a decrease of relative intensity of the band at around 1315 cm−1is accompanied by a considerable increase of relative intensity of the bands in the 1490∼1600 cm−1region when the potential is below −0.7 V, and it is explained by the chemical effect (CE). Simultaneously, the geometry and Raman spectra of neutral and cationic Cu-cytosine complexes are calculated and simulated using the B3LYP/lanl2dz basis. The simulation shows that the relative intensities of Raman spectra depend strongly on the molecular active sites involved in the interaction between the copper electrode and the cytosine molecule. Combining the experimental results with theoretical calculations, we conclude that the adsorptive orientation of cytosine on the copper electrode occurs on the N3site and the carbonyl site when the potential is above and below −0.7 V, respectively. This study also indicates that a combination of SERS and DFT simulations is a valuable tool for studying interactions of biomolecules with metal.

With the technical progress in lasers, charge coupled device detectors, and fiber-optic probes, Raman spectroscopy (RS) is enjoying a strong resurgence in the field of biomedical science, especially in disease diagnosis. During this time we have witnessed more and more in vitroand in vivoapplications of RS, and increasingly frequent reports of its utility. RS enables the extraction of biochemical signatures from biological tissues, and in conjunction with different statistic algorithms, the spectral data with various pathologic attributions can be differentiated and classified depending on their spectral differences, e.g., peak area, peak height or peak shape. This makes RS a potential clinical analytical technique for rapid and non-destructive diagnosis of human diseases. This paper is a review of the biomedical applications of Raman spectroscopic techniques in diagnostics. First, a brief illumination of RS instrumentation and algorithms for data analysis is introduced. Then wide utilization of RS in disease diagnosis is reviewed categorized by different tissues and organs, including brain, eye, body surface organs (breast, skin), abdominal organs (stomach, esophagus, colon, liver), thoracic organs (arteries, lung), reproductive and urinary organs (prostate, cervix, bladder) and hard tissue (bone, teeth). Some other work from our group are also introduced.

For the first time, graphene materials have been conveniently covalently functionalized with polyacetylene through the nitrene chemistry reaction. The resultant functional polyacetylenes became soluble in different organic solvents and were well characterized, thus providing a new approach to prepare graphene‐polymer composite materials.

A novel method for simultaneous determination of sucrose and sunset yellow in retail soft drink without separation by combination of retro-reflected beam interference-based refractive index (RBI) and thermal lens (TL) detections was developed. The method proposed here successfully realized individual measurements of sucrose and sunset yellow in one single sample, while their concentrations were thousands of times different in the sample. Under optimized conditions, a separation-free process was carried out so that sucrose and sunset yellow were quantified at the same time. Limits of detection (LODs) of sucrose and sunset yellow were 0. 21 mg ml−1and 0.23 μg ml−1and the relative standard deviation (RSDs) were 3.9% and 3.07%. The developed method was successfully applied for the simultaneous analysis of sucrose and sunset yellow in retail soft drink. The soft drink containing 123.6 ± 2.6 mg ml−1sucrose and 46.6 ± 1.8 μg ml−1sunset yellow have been simultaneously measured without any separation procedure.

Traditional Chinese medicines (TCMs) are generally mixtures of herbal plants or extracts which comprise hundreds of different constituents with widely difference in the content and physiochemical properties. In order to analyze bioactive compounds in TCMs and control the quality, a large number of analytical tools have been developed, among which capillary electrophoresis (CE) has become a powerful technique with increasing importance. Some formats of CE, including capillary zone electrophoresis, micellar electrokinetic chromatography, non-aqueous CE and capillary electrochromatography have been widely employed for the analysis of TCMs. The general characteristics of these formats are briefly described, and their applications to the analysis of TCMs during the past five years are summarized.

Monodispersed, readily‐grafted, and biocompatible surface‐enhanced Raman spectroscopic (SERS) tagging materials are developed; they are composed of bimetallic Au@Ag nanoparticles (NPs) for optical enhancement, a reporter molecule for spectroscopic signature, and a carbon shell for protection and bioconjugation. A controllable and convenient hydrothermal synthetic route is presented to synthesize the layer‐by‐layer triplex Au–Ag–C core–shell NPs, which can incorporate the Raman‐active label 4‐mercapto benzoic acid (4‐MBA). The obtained gold seed–silver coated particles can be coated further with a thickness‐controlled carbon shell to form colloidal carbon‐encapsulated Aucore/Agshellspheres with a monodisperse size distribution. Furthermore, these SERS‐active spheres demonstrated interesting properties as a novel Raman tag for quantitative immunoassays. The results suggest such SERS tags can be used for multiplex and ultrasensitive detection of biomolecules as well as nontoxic, in vivo molecular imaging of animal or plant tissues.

Micro-Raman spectroscopy (MRS) is used for the first time to our knowledge to investigate brain hippocampus tissue from Alzheimer's disease (AD) infected rats. In situ Raman analysis of tissue sections provides distinct spectra useful for distinguishing AD from normal state. The biochemical changes of brain hippocampus tissue including the deposit of β-amyloid (Aβ) protein, the increase of cholesterol, and hyperphosphorylated tau are observed through MRS when AD occurs. A more convincing multi-Raman criterion based on single Raman peaks, and further in combination with statistical analysis of the entire Raman spectrum, is found capable of classifying brain hippocampus tissues with different pathological features. This study demonstrates the brain hippocampus is an important candidate for considering the early pathological state of AD, and Raman signatures from the brain hippocampus could aid AD diagnosis. In addition, Raman results undoubtedly confirm simultaneous changes of cholesterol and Aβ in the progression of AD.

A new amino silica monolithic column was developed for DNA extraction in a miniaturized format. The monolithic column was prepared in situ by polymerization of tetraethoxysilane (TEOS) and N‐(β‐aminoethyl)‐γ‐aminopropylmethyldimethoxysilane (AEAPMDMS). DNA was loaded in 50 mM tris(hydroxylmethyl)aminomethane–EDTA buffer at pH 7.0 and eluted with 300 mM potassium phosphate solution at pH 10.0. Under optimal condition, a 6.0‐cm monolithic column provided a capacity of 56 ng DNA with an extraction efficiency of 71 ± 5.2% (X± RSD). When the amino silica monolithic column was applied to extract genomic DNA from the whole blood of crucian carp, an extraction efficiency of 52 ± 5.6% (X± RSD) was obtained by three extractions. Since the chaotropic‐based sample loading and organic solvent wash steps were avoided in this procedure, the purified DNA was suitable for downstream processes such as PCR. This amino silica monolithic column was demonstrated to allow rapid and efficient DNA purification in microscale.

Hemoglobin was entrapped in composite electrodeposited chitosan‐multiwall carbon nanotubes (MCNTs) film by assembling gold nanoparticles and hemoglobin step by step. In phosphate buffer solution (pH 7), a pair of well‐defined and quasireversible redox peaks appeared with formal potential at −0.289 V and peak separation of 100 mV. The redox peaks respected for the direct electrochemistry of hemoglobin at the surface of chitosan‐MCNTs‐gold nanoparticles modified electrode. The parameters of experiments have also been optimized. The composite electrode showed excellent electrocatalysis to peroxide hydrogen and oxygen, the peak current was linearly proportional to H2O2concentration in the range from 1×10−6mol/L to 4.7×10−4mol/L with a detection limit of 5.0×10−7mol/L, and this biosensor exhibited high stability, good reproducibility and better selectivity. The biosensor showed a Michaelis–Menten kinetic response as H2O2concentration is larger than 5.0×10−4mol/L, the apparent Michaelis–Menten constant for hydrogen peroxide was calculated to be 1.61 μmol/L.

Though the "RNA world" hypothesis has gained a central role in ideas concerning the origin of life, the scenario concerning its emergence remains uncertain. It has been speculated that the first scene may have been the emergence of a template-dependent RNA synthetase ribozyme, which catalyzed its own replication: thus, "RNA replicase." However, the speculation remains uncertain, primarily because of the large sequence length requirement of such a replicase and the lack of a convincing mechanism to ensure its self-favoring features. Instead, we propose a nucleotide synthetase ribozyme as an alternative candidate, especially considering recent experimental evidence suggesting the possibility of effective nonenzymatic template-directed synthesis of RNA. A computer simulation was conducted to support our proposal. The conditions for the emergence of the nucleotide synthetase ribozyme are discussed, based on dynamic analysis on a computer. We suggest the template-dependent RNA synthetase ribozyme emerged later, perhaps after the emergence of protocells.

Cuprous oxide nanowhisker was prepared by using cetyltrimethyl ammonium bromide (CATB) as soft template, and was characterized by XRD and TEM methods. The electrochemical properties of nano‐Cu2O and nano‐Cu2O‐methylene blue (MB) modified electrode were studied. The experimental results indicate that nano‐Cu2O shows a couple of redox peaks corresponding to the redox of Cu(II)/Cu(I), the peak currents are linear to the scan rates which demonstrate that the electrochemical response of Cu2O is surface‐controlled. The composite nano‐Cu2O‐Nafion‐MB modified electrode shows a trend of decrease of peak currents corresponding to the Cu (II)/Cu (I). However, the electrocatalytic ability of nano‐Cu2O‐MB composite film to dopamine increases dramatically. At this composite electrode, dopamine shows a couple of quasireversible redox peaks with a peak separation of 106 mV, the peak current increases about 8 times and the oxidation peak potential decreases about 200 mV as compared to that at bare glassy carbon electrode. The peak currents change linearly with concentration of dopamine from 1×10−7to 3.2×10−4mol/L, the detection limit is 4.6×10−8mol/L. The composite electrode can effectively eliminate the interference of ascorbic acid and has better stability and excellent reproducibility.

The Ni(II) complex with bis(2,4-dimethyldipyrrin-3-yl)methane, (NiL)2, has been synthesized and characterized by 1H-NMR, UV–Vis, FT-IR, FT-Raman, MS, and elemental analysis. X-ray diffraction analysis at room temperature indicates that the complex crystallizes in triclinic system, space group P−1 with a= 11.344(4), b= 12.703(4), c= 14.936(5) Å, α = 87.017(6)°, β = 75.379(5)°, γ = 75.318(5)°, Mr= 826.31, V= 2014.5(11) Å3, Z= 2. The crystal structure of the title complex reveals that it is a dinuclear double-stranded helical entity. The ligands perform as tetradentate ligands and the ratio of Ni(II) to ligand is 2:2. The central Ni(II) atom is tetracoordinated by four nitrogen donors of two ligands and the coordination geometry of Ni(II) can be considered as a distorted tetrahedron configuration. The IR and Raman spectral analysis, assignment, and discussion are presented.

The synergetic luminescence system of europium for time-resolved fluoroimmunoassay has been studied for the first time. The europium label is bound to the antibody with diethylenetriaminepentaacetic acid anhydride (DTPAA). Once the immunoreaction has been completed, the europium is preferentially dissociated from the antibody in the presence of terbium and measured by laser-induced time resolved fluorimetry. As an example, the determination of human IgG was performed. The detection limit for human immunoglobulin G was 0.25 ng/µl.

Copper(II), nickel(II), cobalt(III) and iron(III) complexes of D-glucosamine, and their complexes with α-glycine were synthesized. The eight novel metal complexes were characterized by means of IR, electronic absorption and ¹H NMR spectroscopy. The surface-enhanced Raman scattering (SERS) spectra of these complexes were studied and by comparison of the spectra information on the SER active sites and adsorption orientation of these complexes was obtained. Copyright © 2001 John Wiley & Sons, Ltd.

A piezoelectric crystal immunosensor for the detection of bovine haemoglobin has been developed. The immobilizing process was monitored by determining the frequency shift of a quartz crystal microbalance (QCM). Bovine haemoglobin concentrations in the range of 0.001 to 0.1 mg/ml could be detected by the system. The influence of the liquid depth on the frequency of QCM was discussed. The interference of bovine serum albumin was also studied.

PbS quantum dots modified WO3 nanoflowers were synthesized on conductive glass through a low-temperature hydrothermal process and a dip coating method. The photoelectrochenical properties of the structure were intensively studied. The results indicated that the structures exhibited an excellent photoelectrochemical performance with a maximum photocurrent density of ~1.8 mA/cm2 and a maximum photoconversion efficiency of ~1.3% under solar light (AM 1.5, 100 mW/cm2) illumination, highlighting its enormous potential in hydrogen generation.

Pterygia, caused by fibrovascular growth of conjunctiva, are a common ophthalmic disease. However, the molecular composition of pterygium tissue has not been completely understood, and therefore the aim of this study is to investigate the spectroscopic differences between normal human bulbar conjunctiva and human pterygium tissue using a confocal Raman system. The high signal-to-noise ratio spectra from pterygium and conjunctiva tissue were obtained by this technique without any sample preparation and the time of detection required less than 3 min. Comparing Raman spectra of two types of tissue, there are obvious changes, including intensity decrease at ∼1585 cm−1 and intensity increase at ∼1748, 1156, and 1521 cm−1 with the lesion of conjunctiva. Additionally, the amide I vibrational mode of proteins in conjunctiva is significantly different than that in pterygium. The use of pathology, immunology, and the peroxidation of the lipids in conjunction with the Raman results indicate that the presence of additional elastic fibers, mast cells, and lymphocytes in pterygium, as compared with normal bulbar conjunctiva, have fewer unsaturated fat acids. The present study demonstrates that Raman spectroscopy can be potentially applied to diagnose pterygia clinically. © 2005 Society of Photo-Optical Instrumentation Engineers.

The current method to classify graphite morphology types of grey cast iron is based on traditional subjective observation, and it cannot be used for quantitative analysis. Since microstructures have a great effect on the mechanical properties of grey cast iron and different types have totally different characters, six types of grey cast iron are discussed and an image-processing software subsystem that performs the classification and quantitative analysis automatically based on a kind of composed feature vector and artificial neural network (ANN) is described. There are three kinds of texture features: fractal dimension, roughness and two-dimension autoregression, which are used as an extracted feature input vector of ANN classifier. Compared with using only one, the checkout correct precision increased greatly. On the other hand, to achieve the quantitative analysis and show the different types clearly, the region segmentation idea was applied to the system. The percentages of the regions with different type are reported correctly. Furthermore, this paper tentatively introduces a new empirical method to decide the number of ANN hidden nodes, which are usually considered as a difficulty in ANN structure decision. It was found that the optimum hidden node number of the experimental data was the same as that obtained using the new method.

The paper describes an energy-dispersive X-ray spectrometer for a scanning electron microscope (SEM-EDXS). It was constructed using the new architecture of a virtual instrument (VI), which is low-cost, space-saving, fast and flexible way to develop the instrument. Computer-aided teaching (CAT) was used to develop the instrument and operation rather than a traditional instrument technique. The VI was designed using the object-oriented program language C++ and compact programmable logical devices (CPLD). These include spectra collection and processing, quantitative analysis and X-ray-intensity distribution analysis. The procedure is described in detail. The VI system gives an e¡ective and user-friendly human interface for the whole analytical task. Some examples are described.