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Colorectal carcinoma (CRC) is a malignant tumor of the digestive system. Cancer-associated fibroblasts (CAFs) are important cellular elements in the tumor microenvironment of CRC, which contribute to CRC progression and immune escape. To predict the survival outcome and therapeutic responses of CRC patients, we identified genes connected with stromal CAF and generated a risk model. In this study, we used multiple algorithms to reveal CAF-related genes in the Gene Expression Omnibus and The Cancer Genome Atlas datasets and construct a risk model composed by prognostic CAF-associated genes. Then, we evaluated whether the risk score could predict CAF infiltrations and immunotherapy in CRC and confirmed the expression of the risk model in CAFs. Our results showed that CRC patients with high CAF infiltrations and stromal score had worse prognosis than those with low-CAF infiltrations and stromal score. We obtained 88 stromal CAF-associated hub-genes and generated a CAF risk model consisting of ZNF532 and COLEC12. Compared with low-risk group, the overall survival in high-risk group was shorter. The relationship between risk score, ZNF532 and COLEC12, and stromal CAF infiltrations and CAF markers was positive. In addition, the effect of immunotherapy in the high-risk group was not as good as that in the low-risk group. Patients with the high-risk group were enriched in chemokine signaling pathway, cytokine-cytokine receptor interaction, and focal adhesion. Finally, we confirmed that the expressions of ZNF532 and COLEC12 in risk model were widely distributed in fibroblasts of CRC, and the expression levels were higher in fibroblasts than CRC cells. In conclusion, the prognostic CAF signature of ZNF532 and COLEC12 can be applied not only to predict the prognosis of CRC patients but also to evaluate the immunotherapy response in CRC patients, and these findings provide the possibility for further development of individualized treatment for CRC. [ABSTRACT FROM AUTHOR]

Matrix multiplication is widely used in a variety of application domains. When the input matrices and the product differ in the memory format, matrix transpose is required. The efficiency of matrix transpose has a non-negligible impact on performance. However, the state-of-the-art software solution and its optimizations suffer from low efficiency due to frequent interference to main pipeline and their inability to achieve parallel matrix transpose and multiplication. To address this issue, we propose AMT, an asynchronous and in-place matrix transpose mechanism based on C2R algorithm, to efficiently perform matrix transpose. AMT performs matrix transpose in an asynchronous processing module and uses two customized asynchronous matrix transpose instructions to facilitate processing. We implement the logic design of AMT using RTL and verify its correctness. Simulation results show that AMT achieves an average of 1.27x (up to 1.48x) speedup over a state-of-the-art software baseline, and is within 95.4% of an ideal method. Overhead analysis shows that AMT only incurs small area overhead and power consumption. [ABSTRACT FROM AUTHOR]

• We present an electrochemical sensor for detecting DNA based on triblock DNA. • PolyA fragment has high affinity to the surface of Au electrode. • A wide linear range (10 pM-10 μM) was obtained with a detection limit of 2.9 pM. • The electrochemical sensor can detect DNA in human serum samples. Electrochemical aptasensor has been broadly advanced for nucleic acid detection. However, it is a long-term goal to design an aptasensor with high specificity, flexibility, and simplicity. In this work, we develop a strategy of triblock DNA probe, which consists of two DNA probes at both ends and ployA fragments in the middle as probe-polyA-probe. PolyA fragment has high affinity to the surface of gold electrode, so it can be assembled on the electrode surface via polyA instead of traditional Au-S bonds. When the target DNA is simultaneously hybridized with the two capture probes, the hybridization stability can be improved due to the strong base stacking effect. [Ru(NH 3) 6 ]3+, as signal probe, can be electrostatically adsorbed on the negatively charged DNA skeleton. A wide linear range (10 pM-10 μM) is obtained with a detection limit of 2.9 pM. Our electrochemical aptasensor has good repeatability, stability, and specificity. More importantly, the electrochemical sensor can successfully detect DNA in human serum samples, which proves its practical value and extensive applicability in complex environment. [ABSTRACT FROM AUTHOR]

Five new phenolic polyketides, namely 3- O -methylwailupemycin G ( 1 ), wailupemycin J ( 2 ), R - and S -wailupemycin K ( 3 and 4 ) and wailupemycin L ( 5 ), as well as the known enterocin ( 6 ) and 5-deoxyenterocin ( 7 ) were isolated and identified from the fermentation broth of Streptomyces sp. OUCMDZ-3434 associated with the marine green algae, Enteromorpha prolifera . Their structures including absolute configurations were elucidated according to the spectroscopic analysis, X-ray single crystal diffraction and the Mosher's experiments. Compound 1 showed comparable α -glucosidase inhibition with an IC 50 value of 0.86 mM to acarbose (IC 50 1.12 mM), and compound 4 was cytotoxic on the HeLa cell with an IC 50 value of 8.2 μM. Compounds 2 , 3 and 7 showed anti-H1N1 virus activity with 47.8%, 42.5% and 60.6% inhibitions, respectively at 50 μg/mL (ribavirin, 45.3% inhibition). [ABSTRACT FROM AUTHOR]

A series of single-strand oligonucleotides functionalized catalytically active gold nanoparticle (AuNPs) as nonspecific receptors have been designed to build a protein sensing array. We take advantage of the correlation between the catalytic activity and the exposed surface area of AuNPs, i.e., DNA-proteins interactions mask the surface area of AuNPs, leading to poor catalytic performance of AuNPs. As the number of DNA-bound proteins increases, the surfaces of AuNPs become more masked; thus, the time of 4- nitrophenol/NaBH4 reaction for color change (yellow ? colorless) of the solution increases. Taking advantage of three nonspecific SH-labeled DNA sequences (A15, C15, and T15) as array sensing elements and the color-change time (CCT) of the solution as signal readout, colorimetric response patterns can be obtained on the array and identified via linear discriminant analysis (LDA). Eleven proteins have been completely distinguished with 100% accuracy with the naked eye at the 30 nM level. Remarkably, two similar proteins (bovine serum albumin and human serum albumin), two different proteins (bovine serum albumin and concanavalin) at the same concentration, and the mixtures of the two proteins with different molar ratios have been discriminated with 100%. The practicability of this sensor array is further validated by high accuracy (100%) identification of 11 proteins in human serum samples. [ABSTRACT FROM AUTHOR]

We have presented an extensible, facile and sensitive multidimensional sensor based on DNA-gold nanoparticle (DNA-AuNP) conjugates for heavy metal ions (Ag + , Hg 2+ , Cr 3+ , Sn 4+ , Cd 2+ , Cu 2+ , Pb 2+ , Zn 2+ , and Mn 2+ ) discrimination. In the presence of metal ions, the excluded effect of DNA and AuNPs with the same negative charges is disrupted, and the amount of FAM-labeled DNA adsorbed on AuNP surfaces increases, resulting in a more obvious fluorescence quenching effect. With the addition of NH 2 OH and HAuCl 4 , AuNPs grow into morphologically varied nanostructures (spherical to branched) depending on the resulting aptamer coverage, which gives rise to different colored solutions (reddish blush, purple and blue) observed by naked eyes. By simply changing the DNA sequences, three sensing elements can be easily obtained and added into this dual-channel multidimensional sensor. 9 heavy metal ions are distinguished by linear discriminant analysis (LDA) and primary component analysis (PCA). A highly sensitive discrimination of metal ion targets with the detection limit as low as 50 nM with 100% identification accuracy is obtained. Remarkably, Cu 2+ and Hg 2+ ions with similar catalytic performance at various concentrations (300 nM, 400 nM, 500 nM, respectively) and the mixture of the two metal ions with different volume ratios (total metal ion concentration: 500 nM) can be successfully discriminated. In addition, nine heavy metal ions are also well-distinguished in river samples, and the accuracy of discrimination of these metal ions samples reaches 100%. Therefore, it will broaden the application field of DNA-AuNP conjugates-based multidimensional sensors. [ABSTRACT FROM AUTHOR]

In this work, we report a simple, ultrasensitive, and feasible colorimetric assay for metal ion (K + , used as a model) via inherent peroxidase-like enzymatic amplification strategy of gold nanoparticles (AuNPs). It is shown that peroxidase-like activity of AuNPs can be improved dramatically by its surface activation with target-specific aptamer molecules. Whereas when the target exists, the aptamers leave the surface of AuNPs in a target concentration-dependent manner, resulting in a decrease of the nanoenzymatic catalytic ability of AuNPs. Thus, K + can be quantified in the presence of AuNPs by using a colorimetric sensing probe (3,3′,5,5′-tetramethylbenzidine). The color change of the solution is relevant to the dose of the target, and this can be achieved with the naked eyes and monitored by UV–vis spectrometry. A linear dependence between the absorbance and target K + concentration is obtained under optimal conditions in the range from 0. 1 nM to 1 μM with a detection limit (LOD) of 0.06 nM estimated at the 3S blank level . The sensitivity displays to be 2–9 orders of magnitude better than those of other K + detection methods. This sensing strategy may in principle be universally applicable for the detection of a range of environmental or biomedical molecules of interest. [ABSTRACT FROM AUTHOR]

In this contribution, we have developed a rapid method for the highly selective detection of mercury ions (Hg 2+ ) using citrate-stabilized triangular silver nanoplates (AgNPs). The colorimetric sensor strategy is based on the aggregation of Hg 2+ -coated AgNPs with the assistance of two amino groups of lysine, resulting in a color change of AgNP solution from blue to mauve or gray. The sensor enables the analysis of Hg 2+ with a minimum detectable concentration that corresponds to 50 nM. Meanwhile, the strategy offers excellent selectivity toward Hg 2+ against other cations. The validation of this method is carried out by analysis of Hg 2+ in tap water with satisfying recoveries over 91.35–106%. [ABSTRACT FROM AUTHOR]

In this study, a simple and highly sensitive colorimetric assay of H 2 O 2 using triangular Ag nanoplates has been carried out. In the presence of H 2 O 2 , the Ag nanoplates are etched from triangle to round, which leads to the vanishment of the surface plasmon resonance (SPR) absorption at 400 nm and significant decrease the absorbance of the band at 670 nm. The color change of the reaction system from the initial blue to mauve can be observed. This proposed method can determine H 2 O 2 with a dynamic range of 50 nM to 1 μM and a low detection limit of 1.36 nM. The high sensitivity of the triangular nanoplates can be ascribed to highly reactive edges/tips, and strongly tip sharpness and aspect ratio dependent SPR absorption of the triangular nanostructure. This sensing system is further extended to the detection of glucose by H 2 O 2 generated from the enzymatic oxidation of glucose, and thus holds great promises in clinical applications. [ABSTRACT FROM AUTHOR]

Here, a simple, and highly sensitive fluorescent assay is designed to monitor K + . The versatile, robust biosensing strategy is based on the specific recognition utility of label-free aptamers with their targets and PicoGreen dye as the signal probe. The aptamers undergo a conformational change to a secondary structure such as G-quadruplex in the presence of targets. In addition to a conformational change with its targets, the remaining single-stranded DNA (ssDNA) aptamer form a duplex structure with its complete complementary sequence. Conformational changes of aptamers as well as fluorescence amplification produce clear signal-off in the presence of targets. Fluorescent assay employing this mechanism for the detection of K + is highly sensitive, and selective. The detection limit of the K + assay is determined to be 2.37 pM. The sensing strategy is low-cost and simple in its operation without requirement for complex labeling of probe DNA or sophisticated synthesis of the fluorescent compound. Also, the method has less structural requirement of complexes of aptamers with their targets, thus rending its wilder applications for various targets. [ABSTRACT FROM AUTHOR]

We report on a probe for the colorimetric and bare-eye detection of dopamine (DA). The optical effect is based on the finding that DA inhibits the melamine-induced aggregation of red gold nanoparticles (AuNPs) to form blue AuNP clusters. We presume that the aggregation induced by melamine is due to its strong hydrogen-bonding interactions with DA. The color changes can be monitored by spectrophotometry or the bare eye. The probes works over the 33 nM to 3.33 mM DA concentration range, and levels down to 33 nM can be quantified. The nanoprobe was successfully applied to the determination of DA in spiked serum. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Herein, a label-free and highly sensitive electrochemical aptasensor for the detection of angiogenin was proposed based on a conformational change of aptamer and amplification by poly(diallyldimethyl ammonium chloride) (PDDA)-functionalized graphene/gold nanoparticles (AuNPs) composites-modified electrode. PDDA-functionalized graphene (P-GR) nanosheets as the building block in the self-assembly of GR nanosheets/AuNPs heterostructure enhanced the electrochemical detection performance. The electrochemical aptasensor has an extraordinarily sensitive response to angiogenin in a linear range from 0.1 pM to 5 nM with a detection limit of 0.064 pM. The developed sensor provides a promising strategy for the cancer diagnosis in medical application in the future. [ABSTRACT FROM AUTHOR]

We provide a highly sensitive and selective colorimetric assay to detect mercury ions (Hg 2+ ) in aqueous environment using thiocyanuric acid (TCA) molecule-functionalized gold nanoparticles (AuNPs). This method is based on the thiophilicity of Hg 2+ and AuNPs as well as the unique optical properties of TCA-functionalized AuNPs. In the presence of TCA, AuNPs aggregate due to the strong attraction between thiol groups of TCA and surface-bounded AuCl 4 - /AuCl 2 - ions, which induces the visible color change from red to blue. With the addition of Hg 2+ , Hg 2+ is more apt to interact with thiols than AuNPs. Thus, Hg 2+ can remove the AuNPs of the TCA-functionalized AuNPs and trigger AuNP aggregation redisperse again. This assay can selectively detect Hg 2+ with the detection limits as low as 0.5 nM in aqueous solution. [ABSTRACT FROM AUTHOR]

We are presenting a colorimetric assay for mercury (II) ions. It is based on citosan-functionalized gold nanoparticles (AuNPs) that act as a signaling probe. Hg (II) induces the aggregation of the chitosan-AuNPs through a chelation reaction that occurs between chitosan and Hg (II). This results in a strong decrease of the absorbance of the modified AuNPs and a color change from red to blue. This sensing system displays excellent selectivity over other metal ions and a detection limit as low as 1.35 μM which is lower than the allowed level of Hg (II) in drinking water (30 μM) as defined by World Health Organization. The method is inexpensive, facile, sensitive, and does not require the addition of other reagents in order to improving sensitivity. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A colorimetric assay for the ultrasensitive determination of thrombin based on cationic polymer and gold nanoparticles was presented, in which unmodified gold nanoparticles (AuNPs) was used as probes and 21-mer thrombin-binding aptamer (TBA) as sensing elements. Upon the addition of thrombin, TBA interacted specifically with thrombin to form a G-quadruplex structure. As a result, the conformation change facilitated the cationic polymer, poly(diallyldimethylammonium chloride) (PDDA)-induced AuNP aggregation. Thus, the visible change in color from wine-red to blue–purple was readily seen by the naked eye. The colorimetric sensor could detect thrombin down to 1pM with high selectivity in the presence of other interferring proteins. Furthermore, the assay was successfully employed to determine thrombin in human serum sample, which suggested its great potential for diagnostic purposes. [Copyright &y& Elsevier]

Highlights: [•] Hourglass-like Ni(OH)2 was prepared via a simple and facile route in solution. [•] The sensor has a detection limit of 80nM. [•] The sensor shows much better catalytic performance compared with bulk material. [•] The sensor shows a great potential for practicable applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] A signal-off architecture for lysozyme detection was designed. [•] The sensor has a linear range (7–30nM) with a detection limit of 1nM. [•] The sensor shows a high sensitivity, good selectivity and satisfactory stability. [•] The sensor shows a great potential for practicable applications. [Copyright &y& Elsevier]

Highlights: [•] The preparation method of flower-shaped Ni/Al layered double hydroxide (LDH) is quite simple. [•] The Ni/Al-LDH has great adsorption capacity owing to its flower-shaped nature. [•] The very good linear relationship toward glucose can be obtained in two regions: 1–100μM and 0.5–21mM. [•] The sensor has a detection limit of 0.11μM. [•] The sensor possesses high sensitivity, good stability and excellent repeatability. [•] The sensor shows a great potential for practicable applications. [ABSTRACT FROM AUTHOR]

Abstract: Herein, a label-free and highly sensitive electrochemical impedance spectroscopy (EIS) aptasensor for the detection of potassium ion (K+) was developed based on a conformational change in which a K+-stabilized single stranded DNA (ssDNA) with G-rich sequence was used as the recognition element. In the measurement of K+ ions, the change in interfacial electron transfer resistance (R ct) of the sensor using a redox couple of [Fe(CN)6]3−/4− as the probe was monitored. In the presence of K+, the G-rich DNA folded into the G-quadruplex structure, and then K+ can bind to the G-quadruplex structure, leading to an increase in the R ct. The R ct increased with K+ concentration, and the plot of R ct against the logarithm of K+ concentration is linear over the range from 0.1nM to 1mM with a detection limit of 0.1nM. Other metal ions, such as Ca2+, Mg2+, Na+, Li+, Al3+, Zn2+, Cu2+, and Ni2+ caused no notable interference on the detection of K+. The scheme reported herein is applicable to the detection of other kinds of G-rich aptamer-binding chemicals and biomolecules. [Copyright &y& Elsevier]

Highlights: [•] A simple and novel colorimetric method for detection of K+ was developed. [•] The aptasensor exhibited low detection limit and wide linear range to K+. [•] This method was able to detect K+ with high selectivity. [•] This colorimetric method exhibited excellent applicability. [ABSTRACT FROM AUTHOR]

As the properties of nanomaterials are strongly dependent on their size, shape and nanostructures, probing the relations between macro-properties and nanostructures is challenging for nanoscientists. Herein, we deliberately chose three types of Ni(OH)2 with hexagonal, truncated trigonal, and trigonal hourglass-like nanostructures, respectively, as the electrode modifier to demonstrate the correlation between the nanostructures and their electrocatalytic performance towards L-histidine. It was found that the hexagonal hourglass-like Ni(OH)2 sample had the best electrocatalytic activity, which can be understood by a cooperative mechanism: on one hand, the hexagonal sample possesses the largest specific surface area and the tidiest nanostructure, resulting in the most orderly packing on the electrode surface; on the other hand, its internal structure with the most stacking faults would generate a lot of unstable protons, leading to an enhanced electronic conductivity. The findings are important because they provide a clue for materials design and engineering to meet a specific requirement for electrocatalysis of L-histidine, possibly even for other biomolecules. In addition, the hexagonal Ni(OH)2-based biosensor shows excellent sensitivity and selectivity in the determination of L-histidine and offers a promising feature for the analytical application in real biological samples. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we described signal amplification architecture for electronic aptamer-based sensor (E-AB), which is applicable to a wide range of aptamers. Herein, we only take lysozyme as the representative sensing target. The amplification method was based on the network of thiocyanuric acid (TCA)/gold nanoparticles (AuNPs) modified with ssDNA. The binding event can be detected by a decrease in the integrated charge of the surface-bound [Ru(NH3)6]3+ which electrostatically absorbed onto the negatively charged phosphate backbones of DNA. In the presence of target molecules, a large amount of TCA/AuNP/ssDNA network associated with [Ru(NH3)6]3+ would be removed from the electrode surface, leading to a significant decrease of redox current. Cyclic voltammetry (CV) signals of [Ru(NH3)6]3+ provides quantitative measures of the concentrations of lysozyme, with a linear calibration ranging from 5pM to 1nM and a detection limit is 0.1pM. The detection limit of the proposed sensor is one order of magnitude and three orders of magnitude more sensitive than the detection limits in the absence of TCA (5pM) and in the absence of TCA/AuNP/ssDNA network (0.5nM). This amplification method is promising for broad potential application in clinic assay and various protein analysis. [Copyright &y& Elsevier]

Abstract: A highly sensitive and specific electrochemical aptasensor for Cu2+ detection based on gold nanoparticles (AuNPs) is presented. In this work, AuNPs offered a big surface area to immobilize a large number of aptamers and excellent electrochemical signal transduction. Its high sensitivity, low detection limit, and wide detection range are the main advantages over our former copper aptasensor. The peak current increased proportionally to the Cu2+ concentration over the range from 0.1nM to 10μM with a detection limit of 0.1pM. The presence of other divalent metal ions did not affect the detection of Cu2+, which indicates a high specificity of Cu2+ detection could be detected. Rapidity, simplicity, and excellent selectivity make it suitable for practical use in determination of Cu2+ from lake samples. [Copyright &y& Elsevier]

Abstract: A simple, highly sensitive, and label-free electrochemical impedance spectroscopy (EIS) aptasensor based on an anti-lysozyme-aptamer as a molecular recognition element, was developed for the detection of lysozyme. Improvement in sensitivity was achieved by utilizing gold nanoparticles (AuNPs), which were electrodeposited onto the surface of a gold electrode, as a platform for immobilization of the aptamer. To quantify the amount of lysozyme, changes in the interfacial electron transfer resistance (R et) of the aptasensor were monitored using the redox couple of an [Fe(CN)6]3−/4− probe. The R et increased with lysozyme concentration. The plot of R et against the logarithm of lysozyme concentration is linear over the range from 0.1pM to 500pM with a detection limit of 0.01pM. The aptasensor also showed good selectivity for lysozyme without being affected by the presence of other proteins. [ABSTRACT FROM AUTHOR]

Abstract: A one-step electrochemical sensor for sensing of potassium ion (K+) based on the conformational change of a single stranded DNA (ssDNA) with G-rich sequence was presented. The introduction of K+ induced folding of the aptamer, and the Fc moiety approached the electrode surface to produce measurable electrochemical signals. The aptasensor had a lower detection limit at 0.1nM, which was an excellent sensitivity compared with other methods for K+ detection. The proposed approach showed high selectivity and minimized the nonspecific adsorption, so that it was used for the detection of target K+ in the human serum sample. [Copyright &y& Elsevier]

A sensitive aptasensor for detection of l-histidine based on the switching structure of aptamer and gold nanoparticles–graphene nanosheets (GNPs–GNSs) composite was reported for the first time. The fabricated biosensor shows an expanded linear range, excellent sensitivity and selectivity against other amino acids. [ABSTRACT FROM AUTHOR]

This paper presents two economic criteria for guiding the energy storage system (ESS) sizing in grid-connected microgrids. The internal power output model and the economic operation model of ESS are firstly established. Then, the combination of heuristic adjustment strategy and hybrid particle swarm optimization algorithm are introduced to solve the optimal operation model of ESS. Then according to the ESS life model and cost-benefit analysis, a static investment economic criterion which is easy and simple to be calculated is proposed to demonstrate the economic feasibility of ESS investment programs in the short term. Considering the time value of currency, a dynamic investment economic criterion is proposed later for long-term investment projects. Furthermore, the ESS sizing boundary of achieving profits could be also obtained according to the criteria which can indicate the economic attractiveness or resistance to ESS investors in the microgrid. A case study has verified its effectiveness. At the same time, sensitivity analysis is given to show the impact on key parameters, such as investment unit price and electricity purchase price on ESS investment. [ABSTRACT FROM AUTHOR]

A new type of ZnSn(OH)6 / SrSn(OH)6 composite photocatalyst was prepared by a simple co-precipitation method. The structure, morphology and light absorption properties of the samples were characterized by XRD, XPS, UV-Vis, N2 adsorption and desorption, scanning electron microscope(SEM), transmission electron microscope(TEM). Its photocatalytic performance was evaluated by toluene target pollutant. The results show that compared with the pure phase SrSn(OH)6 and ZnSn(OH)6, the composite material ZnSn(OH)6 / SrSn(OH)6 has significantly enhanced ultraviolet light absorption capacity, and the recombination efficiency of photogenerated carriers reduce. Furthermore, the efficiency of photocatalytic degradation of toluene is enhanced. The degradation rate of toluene in the composite sample ZSH/SSH-10(molar ratio is 10%) is more than 58%, which is 1. 35 times that of SrSn(OH)6 monomer. The degradation of toluene for ZSH/SSH-10 catalyst is still 51% after recycling 5 times, indicating that the catalyst has good recycling stability. [ABSTRACT FROM AUTHOR]

A colorimetric method is described for the determination of uric acid (UA). The assay is based on oxidative etching of silver nanoparticles (AgNPs) by chloroauric acid (HAuCl4). The presence of UA suppresses the redox reaction between AgNPs and HAuCl4 because a competitive reaction occurs between HAuCl4 and UA. This results in a color change of the solution from brown to yellow. In parallel, the absorbance is blue shifted from 477 to 428 nm. The method has a detection limit as low as 30 pM (at S/N = 3) and a linear response range that covers the 0.1 nM to 0.1 mM UA concentration range. The reliability of the method was successfully demonstrated by analyzing spiked serum samples. [ABSTRACT FROM AUTHOR]

A colorimetric array for metal ions is described that is based on the de-aggregation of papain-capped gold nanoparticles (AuNPs) for discrimination of metal ions. The functionalized AuNPs were used as colorimetric probes, and three chelating agents (tripolyphosphate, citrate, and ethylenediamine tetraacetate were employed as the recognition receptors. In the absence of metal ions (Fe3+, Cr3+, Co2+, Mg2+, Pb2+, Ca2+, Zn2+, Ti4+, and Sn4+ were studied), the capped AuNPs are well dispersed in solution. In the presence of these ions, the metal ions bind papain and cause the AuNPs to aggregate. This causes a color change from red to purple. Different chelating agents induce different affinities between metal ions and papain. This results in distinct colorimetric response patterns. Linear discriminant analysis is used to discriminate the various metal ions on a three-dimensional spatial dispersion graph. [ABSTRACT FROM AUTHOR]

There is growing interest in developing a high-performance sensor array for detection and discrimination of antioxidants owing to their widespread use and essential role in the human body. The present work unveils a novel colorimetric sensor array for colorimetric discrimination of antioxidants based on the red, green, and blue alteration (ΔRGB) pattern recognition. In this sensor array, three concentrations of AgNO3 were used as sensing elements, and gold nanoparticles (AuNPs) were employed as a colorimetric probe. In the presence of antioxidants, the sensor array produces unique colorimetric response patterns for the discrimination of these antioxidants due to different reactivities between three different concentrations of AgNO3 and each antioxidant, leading to deposition of different quantities of Ag nanoshells on the surface of AuNPs, enabling an excellent discrimination of six antioxidants (catechin, epigallocatechin 3-gallate, epicatechin, epigallocatechin, epicatechin 3-gallate, and gallocatechin) at a 20 nM level, when linear discriminant analysis (LDA), hierarchical cluster analysis (HCA), centroid diagram, spidergram, and color contour profiles were smartly combined. Furthermore, different concentrations of antioxidants and binary antioxidant mixtures, even ternary mixtures, could also be discriminated with this sensor array. Finally, the sensor array was successfully used for the discrimination of antioxidants in serum samples, demonstrating its potential applications in the diagnosis of antioxidant-related diseases. [ABSTRACT FROM AUTHOR]

Recently, nanozyme-based sensing platforms have attracted widespread attention due to their excellent performance in practical applications. In this paper, phosphorus-doped porous materials were synthesized by a one-step method and metal-doped with different metal salts. The results show that the iron-containing porous nitrogen-phosphorus material (FeNPC) has the best peroxidase activity. FeNPC catalyzes hydrogen peroxide to generate hydroxyl radical (•OH) which oxidizes colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB. When the above system encounters ferulic acid, the blue product will be inhibited, and the color of the reaction solution will change, so ferulic acid can be detected by the colorimetric method. Ferulic acid is an antioxidant used in humans as an antibacterial and antiviral drug. The detection limit of this colorimetric sensor is as low as 1.3 nM. Compared with other detection methods, the colorimetric method is simple, fast, and cheap and has a good development prospect. [ABSTRACT FROM AUTHOR]

Abstract We develop a glucose oxidase (GOx)-mediated strategy for detecting glucose based on oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB), which is generated from Cu2+-catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB)-H 2 O 2 reaction, as colorimetric readout. The sensing system involves two processes: generation of H 2 O 2 from GOx-catalyzed oxidation of glucose, and H 2 O 2 -induced the oxidization of TMB via the catalysis of Cu2+. The H 2 O 2 formed by GOx-catalyzed oxidation of glucose oxidizes colorless TMB to blue oxTMB, thus enhancing the absorbance intensity at 670 nm. Therefore, we draw a conclusion that the enhancement in colorimetric signal relies directly on H 2 O 2 concentration, which, in turn, depends on glucose concentration. This color change can be used not only for visual detection of glucose by naked eyes but for reliable glucose quantification in the range from 1 to 100 nM with a detection limit of 0.21 nM. The method possesses the following advantages: simple design, low experimental cost, and no any additional experimental equipment for heating, illuminating, or bubbling. Graphical Abstract Unlabelled Image Highlights • A GOx-mediated strategy for detecting glucose based on oxTMB, which is generated from Cu2+-catalyzed TMB-H 2 O 2 reaction. • The enhancement in colorimetric signal relies directly on H 2 O 2 concentration. • The method exhibits an ultrasensitive detection of glucose with the detection limit down to 0.21 nM. • The method is universally applicable for detection of other H 2 O 2 -mediated substrates and enzymes. [ABSTRACT FROM AUTHOR]

Breaking the restrictions of a lock-and-key sensing strategy which relies only on the most dominant interactions between the sensing element and target, here, we develop a colorimetric sensor array with three kinds of cationic polymers (polydiallyl dimethylammonium chloride (PDDA), chitosan (CTS), and cetyltrimethylammonium bromide (CTAB)) as nonspecific receptors. Diverse interactions between cationic polymers and proteins make gold nanoparticles (Au NPs) exhibit different aggregation behaviors, resulting in changes in color and absorbance of Au NPs. Based on the diverse colorimetric response patterns, seven proteins were successfully discriminated visually at the 20 nM level by linear discrimination analysis (LDA). Furthermore, the practicability of the sensor array was validated by the successful identification of proteins without any overlap in human serum samples. [ABSTRACT FROM AUTHOR]

A dual-signal sensor array for highly sensitive identification of biothiols is reported based on different optical responses of MnO2/curcumin (CUR) system to different biothiols. The addition of MnO2 nanosheets (MnO2 NSs) quenches the fluorescence of CUR, and the color of the mixture changes from yellow to brown. In the presence of reductive biothiols, MnO2 NSs are etched and lose their fluorescence quenching ability, resulting in an increase in the fluorescence intensity of CUR at 540 nm and a decrease in the absorbance at 430 nm. The sensor array generates specific response modes based on the varying reduction abilities of different biothiols, which can be distinguished by linear discriminant analysis (LDA). The sensor array successfully distinguished five biothiols (glutathione (GSH), dithiothreitol (DTT), cysteine (Cys), mercaptoethanol (ME), and homocysteine (Hcy)) across a wide concentration range (1 μM-100 μM) and biothiol mixtures with varing molar ratios. [ABSTRACT FROM AUTHOR]

Hourglass‐like Ni(OH)2nanostructures were selected to serve as electrode modifiers to demonstrate the correlation between the structure of nanomaterials and their electrocatalytic activity on L‐histidine. All three types of Ni(OH)2 nanostructure‐modified electrodes have a lower detection limit and wider linear range than the commercial materials. The electrocatalytic activity of these unique nanostructures was found to not only depend on their external architecture, but also on their relevant internal degree of crystallinity. These findings may enable the design of new and better electrocatalytic materials by using shape‐controlled nanoparticles. For more details see the Full Paper by Li and Guo et al. on page 501 ff. [ABSTRACT FROM AUTHOR]

We have proposed a colorimetric sensing assay exploiting the formation of gold amalgamation, combining with Hg 2+ mediated the growth of gold nanoparticles (AuNPs) for rapid detecting Hg 2+ ions with highly sensitivity and selectivity. In our developed approach, Hg 2+ is reduced to elemental mercury by citrate-capped AuNPs, forming gold amalgamation on the surface of AuNPs. AuNP-Hg 2+ interaction modulates the growth of AuNPs which is formed in the HAuCl 4 /NH 2 OH reaction. The rate of AuNP growth is highly dependent on the target concentration. AuNPs with low Hg coverage grow into spherical AuNPs with slow growth rate, which generates red-colored solutions. Whereas, AuNPs with high Hg coverage accelerate the growth of spherical AuNPs with a larger particle size, which generates blue colored solutions. At higher concentration, however, the growth rate of AuNPs begins to decrease. As the concentration of Hg 2+ increases till the saturation of Hg onto the surface of AuNPs, the growth of the AuNPs is inhibited due to full coverage of Hg on the AuNP surface. On the basis of this principle, Hg 2+ can be well determined ranging from 0.5 to 10 nM with a 0.26 nM of the detection limit. [ABSTRACT FROM AUTHOR]

A growing body of evidence indicates that lysozyme plays a significant role as an indicator for many diseases and a drug for treatment of infections, ulcers and to study the spatial conformation, enzyme kinetics, and molecular immunology. Therefore, highly sensitive determination of lysozyme is necessary and vital in a wide variety of fields. In this work, we put forward a simple but effective strategy for colorimetric visualization of lysozyme based on iodide-responsive Cu@Au nanoparticles (Cu@Au NPs) as well as the iodide-catalyzed H 2 O 2 -TMB (3,3,5,5-tetramethylbenzidine) reaction system. Colorimetric detection is applied because of its simplicity, fast response for analysis, high detection limit, low costs and practicality. In our strategy, iodide is applied for the reason that it can induce an obvious color change of the Cu@Au nanoparticles solution from gray to red, along with the change of morphologies of the Cu@Au nanoparticles from irregular to spherical. Consequently, this phenomenon results in colorimetric signal variation of the iodide-catalytic H 2 O 2 -TMB system. What's more, by quite simple biomolecule modification on the Cu@Au nanoparticles surface, an all-purpose colorimetric platform is established for the accurate detection of lysozyme, which could lead to the change of Cu@Au NP concentration through molecular recognition. The results show that modified Cu-Au NPs successfully achieved a simple, selective, visualized, and ultrasensitive detection of lysozyme with a linear range from 10 −7 to 10 −3 M and a detection limit of 60 nM. [ABSTRACT FROM AUTHOR]

We report on a method for highly sensitive and selective colorimetric determination of Hg(II) via a signal amplification strategy. Cu@Au nanoparticles (NPs) are found to exhibit intrinsic peroxidase-like activity and can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine by HO. This is accompanied by a solution color change from colorless to green (with an absorption peak at 655 nm). The catalytic capability of the Cu@Au NPs (pale green) is strongly enhanced by a Cu@Au-Hg trimetallic amalgam (bluish), and this effect can be applied directly to the determination of Hg(II). The limit of detection as observed with the unaided eye is 10 nM, which is at least one order of magnitude lower than that of the known AuNP-based colorimetric assay. Due to excellent specificity of the amalgamation process, the assay is highly selective for Hg(II) and is not interfered by other metal ions in up to 0.5 μM concentrations. This assay was successfully applied to the determination of Hg(II) in tap water. In view of these advantages, we expect this colorimetric method to become an attractive tool for the quantitation of Hg(II) in biological, environmental, and food samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • We design a visual sensor array based on PtNi NWs-TMB-H 2 O 2 system at three pH values. • PtNi NWs show good peroxidase-like activity due to synergistic catalytic effect of Pt and Ni. • The adsorption of S from different thiophenes on PtNi NWs led to varying peroxidase-like activities. • The color variances serve as array's "fingerprints" to recognize six thiophenes at 1 µM. Electronic tongue capable of identifying thiophene compounds can promote early-stage environmental pollution monitoring and assist in environmental governance. Herein, a pH-modulated colorimetric sensor array based on PtNi nanowires (NWs) with peroxidase-like activity is designed for discrimination of thiophene compounds. The simplicity of the construction of this sensor array lies in the fact that it is composed of only one nanomaterial-3,3′,5,5′-tetramethylbenzidine (TMB)-H 2 O 2 system at three different pH values, which largely simplifies the programmatic design of the sensor array. Besides, in terms of sensing principle, the adsorption of sulfur from thiophene compounds on PtNi NWs alters the electronic state of their active centers, resulting in different peroxidase-like activities at different pH values. The color variances brought by the changes serve as "fingerprints" to successfully recognize six thiophene compounds as low as 1 µM level. Notably, PtNi NWs show splendid peroxidase-like activity (12.66 U/mg), far outweighing that of Pt NWs (2.62 U/mg), thanks to synergistic catalytic effect of Pt and Ni. [ABSTRACT FROM AUTHOR]

The content of amino acids in human body is closely related to human health and plays an important role in physiological regulation and medical function. In order to recognize a variety of amino acids, an electrochemical sensor array based on poly(3,4-ethylenedioxythiophene) (PEDOT) electrode was established by using two kinds of electropolymerizers, i.e., citrate and the mixture of citrate and potassium nitrate as sensing elements. Different electropolymerizers lead result in different amount of negative charge on PEDOT electrode, which leads to different adsorption capacity for positive charge amino acids and different repulsion capacity for negative charge amino acids, bringing about obvious changes in differential pulse voltammetry (DPV) current. The five amino acids were accurately identified by linear discriminant analysis (LDA), and the electrochemical sensor array was successfully applied in the differential detection of amino acids in milk. [Display omitted] • 1. An electrochemical sensor array based on poly(3,4-ethylenedioxythiophene) electrode was established. • Citrate and the mixture of citrate and potassium nitrate as sensing elements of the sensor array. • The five amino acids were accurately identified by linear discriminant analysis. • The sensor array was successfully applied in the discrimination of amino acids in human urine. [ABSTRACT FROM AUTHOR]

Nanozymes have both the high catalytic activity of natural enzymes and the stability and economy of mimetic enzymes. Research on nanozymes is rapidly emerging, and the continuous development of highly catalytic active nanozymes is of far-reaching significance. This work reports heteroatomic nitrogen (N) and phosphorus (P) double-doped mesoporous carbon structures and metallic Fe coordination generated sponge-like nanozymes (Fe/NPCs) with good peroxidase activity. On this basis, we constructed a highly sensitive colorimetric sensor with cysteine and phenol as simulated analytes using Fe/NPCs nanozymes, and the response limits reached 53.6 nM and 5.4 nM, respectively. Besides, the method has high accuracy in the detection of cysteine and phenol at low concentrations in serum and tap water, which lays a foundation for application in the fields of environmental protection and biosensors. [ABSTRACT FROM AUTHOR]

Although nanozyme engineering has made tremendous progress, there is a huge gap between them and natural enzymes due to the enormous challenge of precisely adjusting the geometric and electronic structure of active sites. Considering that intentionally adjusting the metal-carrier interactions may bring the promising catalytic activity, in this work, a novel Mo atom nanocluster is successfully synthesized using nitrogen-doped Mxene (Mo ACs /N-MXene) nanozymes as carriers. The constructed Mo ACs /N-MXene displays excellent peroxidase-like catalytic activity and kinetics, outweighing its N-MXene and Mo nanoparticles (NPs)-MXene references and natural horse radish peroxidase. This work not only reports a successful example of Mo ACs /N-MXene nanozyme as a guide for achieving peroxidase-mimic performance of nanozymes for colorimetric glutathione sensing at 0.29 μM, but also expands the application prospects of two-dimensional MXene nanosheets by reasonably introducing metal atomic clusters and nonmetal atom doping and exploring related nanozyme properties. [Display omitted] • We design Mo atom nanoclusters supported by N-doped Mxene peroxidase-like nanozyme. • We construct a colorimetric nanozyme sensor based on Mo ACs /N–Ti 3 C 2 T x for colorimetric GSH sensing. • DFT theoretical results reveal that N-doping enhances the peroxidase-like catalytic activity of Mo ACs /Ti 3 C 2 T x. • GSH levels in cell lysate of Hep-2 cells were analyzed with our Mo ACs /N-MXene nanozyme sensor. [ABSTRACT FROM AUTHOR]

In recent years, environmental pollution has attracted widespread global attention. Among them, environmental problems caused by heavy metal pollution pose a serious threat to human health and ecosystems. Mercury is a common heavy metal pollutant with high toxicity and wide distribution. Excessive intake of Hg2+ can cause permanent and severe damage to the nervous system, respiratory system, and kidneys in the human body. Therefore, developing both accurate and fast detection methods for Hg2+ is of great significance. A sensitive Hg2+ colorimetric sensor is designed based on PtNi nanowires (NWs) and Pt NWs with peroxidase-mimetic activity. PtNi NWs and Pt NWs catalyze the reaction of 3,3′, 5,5′-tetramethylbenzidine (TMB) with hydrogen peroxide (H 2 O 2) to produce blue oxidized TMB (oxTMB). The specific interaction of Pt–Hg significantly inhibits the peroxidase-mimetic activity of PtNi NW and Pt NW nanozymes, resulting in a lighter blue color. It is worth noting that compared with specific activity (SA) of Pt NWs (3.31 U/mg), PtNi NWs own superior SA (10.43 U/mg), which inevitably leads to a wider linear range of Hg2+ analysis (1 nM-200 μM) and a lower detection limit (0.6748 nM) for PtNi NWs-based colorimetric sensor, versus linear range (4 nM-5 μM) and LOD of 1.198 nM for Pt NWs-based colorimetric sensor, which are far below the Hg2+ threshold (10 nM) for drinking water set by the US Environmental Protection Agency. Significance : The two nanozyme colorimetric sensors have been successfully used for the evaluation of Hg2+ in complex river water and tap water. Due to the advantages of simple operation, fast response, and high sensitivity, colorimetric sensors have broad application prospects in environmental monitoring. [Display omitted] • We design colorimetric Hg2+ sensors based on PtNi and Pt NWs with peroxidase-like activity. • The specific interaction of Pt–Hg inhibits the peroxidase-like activity of PtNi and Pt nanozymes. • PtNi NWs own superior SA (10.43 U/mg) than that (3.31 U/mg) of Pt NWs. • The two nanozyme colorimetric sensors achieved Hg2+ detection in river water and tap water. [ABSTRACT FROM AUTHOR]

Monitoring ascorbic acid (AA) levels in human body can provide valuable clues for disease diagnosis. Anchoring noble metal single atoms on perovskite substrate is a promising strategy to design electrocatalysts with outstanding electrocatalytic performance. Herein, we design an electrochemical method for detecting AA by utilizing Pt single atoms-doped CsPbBr 3 nanocrystals (Pt SA/CsPbBr 3 NCs) fixed on a glassy carbon electrode as an electrochemical catalyst. The uncharged 3,5,3′,5′-tetramethylbenzidine (TMB) undergoes oxidation to form the positively charged oxidized TMB (oxTMB) owing to the exceptional electrochemical catalytic performance of Pt SA/CsPbBr 3 NCs. Subsequently, the target AA reduces oxTMB to TMB, which is then electrocatalytically oxidized to oxTMB, producing significant oxidation current. In this way, such characteristic provides a sensitive electrochemical strategy for AA detection, achieving a concentration range of 50-fold with the detection limit of 0.0369 μM. The developed electrochemical method also successfully generates accurate detection response of AA in complex sample media (urine). Overall, this approach is expected to offer a novel way for early disease diagnosis. • The Pt SA/CsPbBr 3 was prepared as an electrochemical catalyst for AA detection. • The Pt SA/CsPbBr 3 microstructure contains 3 Pt–O and 1 Pt–Br bonds. • The detection limit of the sensor for electrochemical AA detection is 0.0369 μM. • The sensor achieved accurate detection of AA in complex urine sample. [ABSTRACT FROM AUTHOR]

Adding preservatives to cosmetics have raised many concerns about health issues. Here, we propose a fluorescence sensor array for preservative discrimination based on two types of CsPbBr 3 nanocrystals (NCs) modified with two different thiol compounds (i.e., 6-mercapto-1-hexanol (6-MCH) and dithiothreitol (DTT)). The redox reaction between the sulphydryl of 6-MCH and DTT and the carbon oxygen double bonds of preservatives will enhance the fluorescence intensity, which is due to the depletion of superficially decorated DTT and 6-MCH at CsPbBr 3. By manipulating this mechanism, different preservatives generate unique fluorescence fingerprint responses through the diverse interactions between targets and two CsPbBr 3 NCs. Thus, two types of preservatives, including four formaldehyde releasers and three parabens, were well distinguished at low concentration using linear discriminant analysis (LDA) by this sensor array. Remarkably, preservative identification in hand cream further proves the array's practical applicability in complex environment. • We propose a fluorescence sensor array for preservative discrimination based on sulphydryl-functionalized CsPbBr 3 NCs. • The redox reaction between the sulphydryl and the C O of preservatives enhance the fluorescence intensity. • Unique fluorescence fingerprints can be differentiated using linear discriminant analysis • Two types of preservatives, including 4 formaldehyde releasers and 3 parabens, were distinguished at low concentration. [ABSTRACT FROM AUTHOR]

Peroxides in edible oils, whose amounts are measured using the peroxide value, are closely related to human health. Long-term consumption of edible oils with high peroxide values can lead to a variety of human diseases, which highlights the significance of examining oil types and their corresponding peroxide values. For identifying a wide range of edible oils, we established a colorimetric sensor array based on the halogen ion exchange between CsPbBr3 and two iodides (octadecylammonium iodide (ODAI) and ZnI2). Different kinds of edible oils contain distinct peroxidic substances that have the distinct ability to oxidize iodides. After specific types of edible oils react with excess iodides (ODAI and ZnI2), different amounts of residual iodides are left for further halogen exchange with CsPbBr3, resulting in various colorimetric responses, measured in RGB (red/green/blue) values, under fluorescent light. Based on RGB pattern analysis as fingerprints using two anion exchangers (ODAI and ZnI2), our proposed colorimetric sensor array was proved by linear discriminant analysis (LDA) to have an ability to accurately distinguish edible oils at a minimal volumetric concentration of 6.67% in seven real samples. [ABSTRACT FROM AUTHOR]

Abstract: Angiogenin (Ang), one of the most potent angiogenic factor, is related with the growth and metastasis of numerous tumors. This paper presents a very simple and label-free square-wave voltammetry (SWV) aptasensor to detect angiogenin, in which an anti-angiogenin-aptamer was used as a molecular recognition element, and the couple ferro/ferricyanide as a redox probe. At the bare gold electrode, the redox couple (K4[Fe(CN)6]/K3[Fe(CN)6]) can be very easily accessed to the electrode surface to give a very strong SWV signal. At the anti-angiogenin/Au electrode surface, when angiogenin was added to the electrochemical cell, the binding of the analyte results in less availability for a redox reaction, which led to smaller SWV current. To quantify the amount of angiogenin, current suppressions of SWV peak were monitored using the redox couple of an [Fe(CN)6]4−/3− probe. The plot of signal suppression against the logarithm of angiogenin concentration is linear with over the range from 0.01nM to 30nM with a detection limit of 1pM. The aptasensor also showed very good selectivity for angiogenin without being affected by the presence of other proteins in serum. It is the first time to use a very simple method to detect the cancer marker. Such an aptasensor opens a rapid, selective and sensitive route for angiogenin detection and provides a promising strategy for other protein detections. [Copyright &y& Elsevier]

A gold nanoparticle (AuNP)–based sensing strategy based on rapid reduction of Au(I→0) is proposed. As a proof-of-concept study, the proposed sensing principle is designed for simultaneous and colorimetric detection and discrimination of multiple proteins. In the presence of H2O2, the target proteins could reduce Au(I) (i.e. HAuCl2) to AuNPs with different sizes, shapes and dispersion/aggregation states, thus resulting in rapidly colorimetric identification of different proteins. The optical response (i.e. color) of AuNPs is found to be characteristic of a given protein. The color response patterns are characteristic for each protein and can be quantitatively differentiated by statistical techniques. The sensor array is capable of discriminating proteins at concentrations as low as 0.1 μg/mL with high accuracy. A linear relationship was observed between the total Euclidean distances and protein concentration, providing the potential for protein quantification using this sensor array. The limit of detection (LOD) for catalase (Cat) is 0.08 μg/mL. The good linear range (from 0 to 8 μg/mL) has been used for the quantitative assay of Cat. To show a potentially practical application, this method was used to detect and discriminate proteins in human urine and tear samples. [ABSTRACT FROM AUTHOR]