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• Survivin as an effective diagnostic marker of bladder cancer was confirmed. • Sensitivity of survivin mRNA was higher than that of survivin protein. • Immunohistochemical detection of survivin is more effective for diagnosis. Early detection, diagnosis, and treatment take on critical significance in preventing and treating bladder cancer. As indicated by numerous studies, survivin can serve as a biomarker of bladder cancer, whereas the results of a wide variety of studies have been controversial. This paper is to assess the accuracy of survivin in the diagnosis of bladder cancer by a meta-analysis. The studies regarding the diagnosis of bladder cancer using survivin were systematically retrieved from the CNKI, WanFang, CBM, VIP, Web of science, cochrane library and pubmed were extracted, and the literature quality was assessed. Meta-analysis was conducted using STATA 16.0 MP. 2,082 relevant studies were searched, and 40 studies were finally covered for meta-analysis. The pooled specificity and pooled sensitivity of survivin mRNA was 0.95 (95% CI : 0.91, 0.97) and 0.94 (95% CI : 0.88, 0.97). The pooled specificity and pooled sensitivity of survivin protein reached 0.95 (95% CI : 0.90, 0.97) and 0.87 (95% CI : 0.78, 0.92). The pooled positive likelihood ratio, pooled negative likelihood ratio, the area under the curve, and diagnostic odds ratio for survivin mRNA reached 17.7 (95% CI : 10.3, 30.6), 0.07 (95% CI : 0.04, 0.12), 0.98 (95% CI : 0.97, 0.99) and 266 (95% CI : 114, 621), respectively. For survivin protein was 16.4 (95% CI : 7.9, 33.9), 0.14 (95% CI : 0.08, 0.24), 0.97 (95% CI : 0.95, 0.98) and 117 (95% CI : 38, 357), respectively. Survivin takes on great significance in diagnosing bladder cancer. However, due to some limitations in the number and quality of covered studies, this conclusion should be validated through additional higher quality clinical studies. [ABSTRACT FROM AUTHOR]

Root exudate is a major source of soil organic matter and can significantly affect arsenic (As) migration and transformation in paddy soils. Citric acid is the main component of rice root exudate, however, the impacts and rules of citric acid on As bioavailability and rhizobacteria in different soils remains unclear. This study investigated the effects of citric acid on As transformation and microbial community in ten different paddy soils by flooded soil culture experiments. The results showed that citric acid addition increased total As and arsenate (As(V)) in the soil porewater by up to 41-fold and 65-fold, respectively, after 2-h incubation. As(V) was the main As species in soil porewater within 10 days with the addition of citric acid. Non-specifically sorbed As of soils, total Fe and total As were the main environmental factors affecting the soil microbial communities. High-throughput sequencing analysis demonstrated that citric acid addition significantly altered the soil microbial community structure, shifting the Proteobacteria-related reducing bacteria to Firmicutes-related reducing bacteria in different paddy soils. The relative abundance of Firmicutes was promoted by 174–196%. Clostridium -related bacteria belonging to Firmicutes became the dominant genera, which is believed to regulate As release through the reductive dissolution of iron oxides or the direct reduction of As(V) to arsenite (As(III)). However, citric acid addition significantly decreased the relative abundance of Geobacter and Anaeromyxobacter , which are also typical active As(V)- and ferric-reducing bacteria. Real-time quantitative polymerase chain reaction (qPCR) also revealed that the addition of citric acid significantly decreased the relative abundances of Geobacter in the different soils by 8–28 times while the relative abundances of Clostridium increased by 2–5 times. These results provide significant insight on As transformation in different types of rice rhizospheric soils and guidance for the application of rice varieties with low citric acid exuding to restrict As accumulation. [Display omitted] • Citric acid addition increased As(V) and total As in soil porewater in ten soils. • Different soil microbial communities were mainly affected by F1/Fe/As. • Citric acid shifted the main Fe(III)/As(V) reducing bacteria in different soils. • Citric acid decreased gene expression of Geobacter while increased Clostridium. • Citric acid addition increased the gene expression of arsC. [ABSTRACT FROM AUTHOR]

In this work, we first conjugated a short peptide to thrombin binding aptamer (TBA) and bond hemin to the hybrid, effectively rendering hemin/G4-peptide more active over the original hemin/G4, so that a highly sensitive electrochemical thrombin (TB) aptasensor was developed based on it and PtNTs@rGO nanocomposite. It was the first report on the application of hemin/G4-peptide in electrochemical aptasensor. PtNTs@rGO with large surface area served as excellent nanocarrier for high loading of hemin/G4-peptide hybrids, resulting in the formation of hemin/G4-peptide–PtNTs@rGO bioconjugate as the secondary aptamer and further signal enhancement. The specific affinity of aptamer for target TB made the secondary aptamer go into the sensing interface, and then a noticeable current signal was obtained from hemin without additional redox mediators. Due to the collaborative electrocatalysis of hemin/G4-peptide and PtNTs toward H 2 O 2 , which was formed in situ during the process of hemin/G4-peptide-catalyzed oxidation of NADH with dissolved O 2 , the current intensity increased dramatically. Such an electrochemical aptasensing system could be used to detect TB with a linear range of 0.05 pM–60 nM and very lower detection limit of 15 fM. Notably, this method exhibited a higher sensitivity than that of many hemin/G4-based electrochemical strategies for TB detection due to the improvement of the catalytic activity of hemin/G4-peptide. The present works opened a new way for expanding the application of hemin/G4 in biological detection. With the mediator-free, proteinous enzyme-free yet high-sensitivity advantages, this electrochemical aptasensor held great promise for other biomarker detections in clinical diagnostics. [ABSTRACT FROM AUTHOR]

This work establishes a highly sensitive and simple stripping voltammetric method for the direct determination of trace iodide. In the presence of abounding bromide and appropriate amount of cetylpyridine bromide (CPB), the iodine was accumulated on the glassy carbon electrode surface as ion association complex (CPBI 2 Br). After accumulation for a period of time, a linear sweep potential with negative scanning was applied and the I 2 in CPBI 2 Br was reduced again into the solution. Under the optimization conditions, the stripping signals (peak current) were linear relationship with iodide concentration in range of 3.81×10 −3 µg/mL to 0.114 μg/mL and 0.127 μg/mL to 2.54 μg/mL, with a detection limit of 1.02 ng/mL ( S / N =3) for a accumulation time of 180 s. Determination of trace iodine in pharmaceutical sample, kelp and table salt were performed with high accuracy and satisfactory recovery results. [ABSTRACT FROM AUTHOR]

A Cr(VI)-reducing bacteria ( Pseudochrobactrum saccharolyticum LY10) was selected to simulate the biofilm grown in unsaturated habitats containing Cr(VI) and the X-ray fluorescence and absorption methods were used to characterize the temporal and spatial distributions of metal elements in the unsaturated biofilms in the present study. The results indicated that Cr and other elements (Fe, Mn, Ca, K, and Zn) were selectively accumulated in the unsaturated biofilms. Synchrotron radiation micro X-ray fluorescence microscopy (SR-μXRF) analysis revealed that Cr mainly existed in the 10–45 μm layer near the bottom biofilm–membrane interface after 24 h of Cr exposure. The analysis of Cr speciation by X-ray absorption near-edge structure (XANES) spectroscopy analysis further confirmed the bioreduction of Cr(VI) to Cr(III), and the precipitate formed in the biofilms after reduction were most similar to CrPO 4 . This systematic understanding of the accumulation, distribution and reduction process of Cr in the unsaturated biofilms will elaborate to enhance the bioremediation efficiencies for Cr pollution in soil and other environment. [ABSTRACT FROM AUTHOR]

Determination of adenine, hypoxanthine, guanine and xanthine in different parts of pork and beef using high performance liquid chromatography was described. Chromatographic separation was carried out on Waters Atlantis T 3 column (4.6 mm × 250 mm × 5 μm) with column temperature at 30 °C. The mobile phase contained 99% 10.0 mmol/L ammonium formate solution at pH 3.6 and 1.0% methanol. Chromatography was achieved at a flow rate of 1.0 mL/min and detection wavelength at 254 nm. The results indicated that total purine amounts in pork rump and beef sirloin were higher than those in other parts ( P < 0.05). The principal purine bases were hypoxanthine and adenine, and hypoxanthine content was the most highest in all samples ( P < 0.05). As pork rump and beef sirloin contain considerable amounts of total purine and uricogenic purine base, we suggest that excess consumption of them be avoid, whereas pork loin chop and beef rib eye are more suitable for a low-purine diet. [ABSTRACT FROM AUTHOR]

Abstract: A new and sensitive sensor for morphine, based on electrochemically reduced MWNTs-doped graphene oxide (ER-MWNTs-doped-GO) composite film modified glassy carbon electrode, was reported. Electrochemical impedance spectroscopy and scanning electron microscopy were employed to study the characteristic of the ER-MWNTs-doped-GO film. The electrochemical behaviour of morphine on this sensor was investigated in pH 4.5 phosphate buffer solution by cyclic voltammetry and linear sweep voltammetry. Significant advantages were achieved by combining the excellent conductivity of MWNTs and ER-GO with the film forming properties of GO. And some merits for response towards morphine from this sensor were showed such as wide linear range, fine selectivity and sensitivity, low detect limit and easy surface renewing. The application of the proposed method in analysis of real sample was also evaluated with good performance. [Copyright &y& Elsevier]

Cancer is one of the main diseases threatening human health in the world. Doxorubicin (DOX) is a common anti-cancer drug that can be used for chemotherapy to extend a cancer patient's life. It is our common wish that treatment process of cancer is efficient and secure. Therefore, it is of great significance to develop sensitive, rapid and accurate techniques for anti-cancer drug doxorubicin (DOX) detection. Herein, in our work, a ratiometric electrochemical sensor for DOX detection was designed, which based on MB@MWCNTs/UiO-66-NH 2 composites. The porous materials UiO-66-NH 2 magically shoulder double function in our ratiometric electrochemical strategy, which can reduce the interior error caused by the various complex materials. Specifically, on the one hand, it can be used to catalyze DOX, which can provide a great current signal to be detected, on the other hand, its special property of absorbing molecules was utilized to load materials as internal reference. Consequently, we chose methylene blue (MB) as the substance that can generate an internal reference signal, because it is a specific and stable electroactive substance. Then, we added MWCNTs as a part of the material modified on the ratiometric electrochemical platform to enhance the signal of the target due to its feature of good electrical conductivity. Under the optimized conditions, the ratiometric electrochemical sensor displayed a wide linear detection with the range from 0.1 μM to 75 μM and the limit of detection (LOD) of 0.051 μM. The applicability of this method in the analysis of actual human saliva samples has been confirmed by the results of selectivity, stability, and reproducibility tests, which was prospective in clinical application. [Display omitted] • Multiple function MOF was designed for ratiometric electrochemical detection of DOX. • The UiO-66-NH 2 /MWCNTs can bring catalytic reaction towards target to amplify the detection signal. • The multiple function MOF platform can be extended for analysis of other target. [ABSTRACT FROM AUTHOR]

A composite LangmuirBlodgett film prepared from DNA and polyaniline was deposited on the surface of a glassy carbon electrode (GCE) to give a new voltammetric sensor for the β2-agonist salbutamol (SAL). Cyclic voltammetry and electrochemical impedance spectroscopy were employed to study the characteristic of the modified electrode. The electrochemistry of SAL at the modified electrode was investigated at pH 6.8 by cyclic voltammetry and differential pulse anodic voltammetry. The oxidation of SAL at this electrode is an adsorption-controlled irreversible process. A sensitive electroanalytical method for determination of SAL was worked out that displays high precision and good reproducibility. The method was applied to quantify SAL in tablets with satisfactory results. [ABSTRACT FROM AUTHOR]

Abstract: Gold nanoparticles/polyaniline nanocomposite thin film was deposited onto the surface of glassy carbon electrode(GCE) by Langmuir–Blodgett(LB) technology to fabricate a new voltammetric sensor (GNPs/PAn-LB GCE) for epinephrine(EP) and uric acid(UA) detection. Cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy were employed to study the characteristic of the GNPs/PAn-LB film. Electrochemical behaviors of EP and UA at the modified electrode were investigated in pH 6.6 phosphate buffer solutions. A sensitive electroanalytical method for simultaneous determination of EP and UA was proposed with high precision and good reproducibility. [Copyright &y& Elsevier]

The electro-polymerization of l-Theanine was investigated for the first time on glassy carbon electrode and the polymeric conditions and mechanism were discussed in detail. Hereafter, a simple and sensitive electrochemical sensor based on the poly(l-Theanine) film was established for sophoridine sensing. The electrode process of sophoridine was then studied by cyclic voltammetry and its determination was achieved by amperometry. The results revealed that the poly(l-Theanine) membrane effectively decreased the oxidation potential of sophoridine and greatly increased its response current. And this sensor, fabricated easily and simply as well as very easy surface update, showed good response for sophoridine with a wide linear range from 1.0×10−6 to 1.4×10−4 molL−1 and a low detection limit of 5×10−7 molL−1. The application of proposed method in analysis of real sample was also evaluated with good performance. This work promoted the potential applications of amino acid materials in electrochemical sensors. [ABSTRACT FROM AUTHOR]

In the present work, a new voltammetric sensor, Langmuir-Blodgett (LB) film of tetraoxocalix[2]arene[2]triazine (TOCT) modified glassy carbon electrode (LB-GCE), for trace analysis of copper ion in water samples, was prepared. The morphology of LB-GCE was characterized by cyclic voltammetric method, electrochemical impedance spectroscopy, and atomic force microscope. The recognizing mechanism of LB-GCE for copper ion in aqueous solution was discussed. Under the optimum experimental conditions, using square wave stripping voltammetry and accumulation time of 300 s, the peak currents were linear relationship with Cu concentrations in the range of 2 × 10 to 1 × 10 mol L, with detection limit of 1 × 10 mol L. By this method, real samples (lake water, drinking water, and city wastewater) were analyzed with satisfactory results. In addition, the fabricated electrode exhibited a distinct advantage of simple preparation, non-toxicity, good reproducibility, and stability. [ABSTRACT FROM AUTHOR]

We have prepared a new voltammetric sensor for guanine and adenine. It is based on a glassy carbon electrode modified with a Langmuir-Blodgett film made from tetraoxocalix[2]arene[2]triazine. The direct electro-oxidation of adenine and guanine was investigated and the results indicat that in contrast to a bare glassy carbon electrode both guanine and adenine cause an increase in the oxidation peak currents along with a negative shift of the oxidation potentials. The electrode enables the simultaneous determination of guanine and adenine using square wave voltammetry. Analysis of acid denatured calf thymus DNA was carried out and the value of (G + C)/(A + T) was correctly found to be 0.75. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A new composite adsorbent, iron oxide coated zeolite (IOCZ), was characterized and employed for the removal of Cu(II) from aqueous solution using fixed bed column. Scanning electron microscope (SEM), FTIR, X-ray diffraction spectrum (XRD) and BET analyses were used to study the surface properties of the coated layer. The effects of various experimental conditions, such as the flow rate, initial metal concentration and bed depth, were studied. The dynamics of the adsorption process were fitted by Adams–Bohart model and Thomas model. The Thomas model was found suitable for the description of breakthrough curve at all experimental conditions, while Adams–Bohart model was only for an initial part of dynamic behavior of the IOCZ column. The bed depth service time (BDST) model was applied to predict the service times with other flow rate and initial concentration. The theoretical breakthrough curve was compared with experimental breakthrough curve profile in the dynamic process. The saturated column was regenerated by 1moll−1 hydrogen chloride solution and IOCZ could be reused in Cu(II) removal. [Copyright &y& Elsevier]

[Display omitted] • OMC@AuNPs combined with AuPt-MB were firstly applied to immunosensor fabrication. • A facile method was firstly used to prepare OMC@AuNPs composites. • A disposable sandwich-configuration immunosensor was presented for AFP detection. • This immunosensor exhibited good selectivity and sensitivity towards AFP. • Results in detecting human serum samples indicated potential clinical application. Early finding and diagnosis are critical for prevention and treatment of hepatocellular carcinoma (HCC). Alpha-fetoprotein (AFP) is a typical biomarker of HCC. Since AFP level can reflect the severity of HCC, it is essential to ensure the accurate detection of AFP. In this study, through a combination of the advantages exhibited by ordered mesoporous carbon (OMC)@gold nanoparticles (AuNPs) composites and AuPt-methylene blue (AuPt-MB), a disposable ultrasensitive sandwich-configuration electrochemical immunosensor for determination of AFP was designed. Characterized by excellent conductivity, highly ordered pore distribution and great surface area, OMC can be effective in promoting electron transfer and loading a large number of AuNPs. In the meantime, AuNPs can also immobilize AFP-Ab 1 through Au-N bonds. As a new redox-active species, rod-like AuPt-MB demonstrates high conductivity, uniform morphology and excellent biocompatibility, which makes it capable not only to fix AFP-Ab 2 , but also to release electrochemical signals. A wide linearity of 10 fg mL−1-100 ng mL−1 and a low detection limit of 3.33 fg mL−1 (S/N = 3) were obtained. Moreover, the proposed immunosensor exhibited acceptable selectivity, high stability and reproducibility. The excellent performance in detecting serum samples endows the proposed immunosensor with broad prospects of extensive application in the detection of disease biomarkers. [ABSTRACT FROM AUTHOR]

• 2D/3D material amplification strategy was explored. • RGO-TEPA@Cu-MOFs@SiO 2 @AgNPs composites were firstly used as substrate matrix. • A disposable label-free electrochemical immunosensor was presented for NMP22 detection. • This electrochemical immunosensor exhibited good selectivity and sensitivity towards NMP22. • Results in detecting human urine samples indicated potential clinical application. Nuclear matrix protein 22 (NMP22) is a crucial bladder cancer marker, the accurate detection of which is conductive to improving the effectiveness of tumor prevention and treatment. However, due to low sensitivity, it is impossible for conventional immunoassay to detect the trace of NMP22 at the early stages of tumor progression. It is crucial to develop a simple, sensitive and accurate detection method of NMP22. As a variety of two-dimensional (2D) material, reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) demonstrates excellent conductivity and contains abundant amino groups. As a sort of 3D material, silica-modified Cu-based metalorganic frameworks deposited silver nanoparticles (Cu-MOFs@SiO 2 @AgNPs) composites are characterized by large surface area, excellent biocompatibility and water stability, which allows the immobilization of anti-NMP22 in large amounts via Ag-N bonds. Through a combination of the advantages exhibited by 2D material, 3D material, AgNPs and disposable screen-printed electrode, a disposable and sensitive label-free electrochemical immunosensor has been successfully assembled for NMP22 detection. In addition to exhibiting a wide linear range (0.1 pg∙mL−1-1000 ng∙mL−1) and a low detection limit (33.33 fg∙mL−1, S/N = 3), the proposed immunosensor also demonstrated satisfactory selectivity, strong reproducibility and high stability. Moreover, the excellent performance in detecting human urine samples makes it applicable in practice. [ABSTRACT FROM AUTHOR]

A photoelectrochemical platform for thrombin determination was developed based on Au-rGO-CuS as multiple signal amplification elements. CuInS2 QDs was used to sensitize burr-shape TiO2 (b-TiO2) to obtain a strong photocurrent. Under the specific recognition between aptamer and thrombin, a sandwichlike structure was formed and the Au-rGO-CuS-labeled aptamer (S2@Au-rGO-CuS) was immobilized on the electrode surface. This induced a sharp decrease in photocurrent. The phenomenon is mainly due to the fact that CuS NPs can competitively consume the light energy and electron donor with CuInS2/b-TiO2. The rGO can increase the amount of CuS NPs and the Au NPs can accelerate charge transferring which depress the recombination of photogenerated electrons and holes in CuS to further enhance the competitive capacity of CuS. The sandwichlike structure has a steric hindrance effect. Therefore, the S2@Au-rGO-CuS has a multiple signal amplification function for thrombin determination. Under optimal conditions, the PEC aptasensor exhibited a wide linear concentration range from 0.1 pM to 10 nM with a low detection limit of 30 fM (S/N = 3) for thrombin. Besides, the designed aptasensor performed well in the assay of human serum sample, indicating good potential for the determination of thrombin in real samples. [ABSTRACT FROM AUTHOR]

Hydroxypropyl methylcellulose (HPMC) was employed as an intermediate layer to enhance interfacial interaction between chitosan (CS) coating and tangerine fruits, thereby improving the preservation effect. Owing to the low surface tension of tangerine fruit (26.04 mN/m), CS coating solutions showed poor wetting properties on fruit peels (contact angle > 100°). However, by applying a 1.0 % (w / v) HPMC coating on fruits, the contact angle of CS solutions with concentrations of 0.5 %, 1.0 %, and 1.5 % (w/v) decreased to 47.0°, 47.4°, and 48.5°, respectively, whereas the spreading coefficient increased to −16.0 mN/m, −17.6 mN/m and −19.8 mN/m, respectively. Subsequently, the effects of the coatings on fruit quality were investigated. The results demonstrated the promising performance of HPMC-CS two-layer coating in inhibiting fruit respiration, reducing decay rate, and maintaining nutrient content. Notably, HPMC-1.5%CS coating not only reduced the decay rate of tangerine fruit by 45 % and 31 %, in comparison to the uncoated group (CK) and pure CS coating respectively, but also maintained a high content of ascorbic acid. Therefore, this study confirmed that the use of amphiphilic polymers for improving the surface properties of fruits can effectively facilitate the wetting of hydrophilic coatings on fruits, and significantly improve the fresh-keeping performance of edible coatings. [Display omitted] • Tangerine fruits showed a low surface roughness and a low surface energy. • A two-layer coating of hydroxypropyl methylcellulose (HPMC) and chitosan (CS) was applied on tangerine fruits. • Amphiphilic HPMC coating effectively improved the wettability of chitosan coating solution on tangerine fruits. • HPMC-1.5%CS coating reduced the decay rate of tangerine fruits by 45 %. [ABSTRACT FROM AUTHOR]

Brassinazole-resistant (BZR) transcription factor plays an important role in plant growth and stress resistance through brassinosteroid (BR) signal transduction. However, systematic analysis of the BZR family in dicots remains limited. In this study, we conducted a genome-wide study of four typical dicots: Arabidopsis thaliana , Carica papaya , Vitis vinifera and Populus trichocarpa. Thirty-four BZR gene family members were identified and classified them into three subfamilies. Analysis of promoter and expression patterns revealed crucial role of a pair of homologous BZR genes, PtBZR9 and PtBZR12 , in poplar may play a critical role under abiotic stress. PtBZR9 and PtBZR12 were localised in the nucleus and exhibited mutual interactions. Moreover, transient overexpression (OE) of PtBZR9 and PtBZR12 in poplar enhanced tolerance to drought stress. The phenotypic and physiological characteristics of PtBZR9 and PtBZR12 OE in Arabidopsis mirrored those of transient OE in the poplar. Additionally, PtBZR9 and PtBZR12 can bind to the E-box element. Under exogenous BR treatment, transgenic lines displayed a greater decrease in root length than the wild type. Thus, these findings provide a solid foundation for future research on the complex regulatory mechanisms of BZR genes. • Thirty-four BZR genes were identified, revealing a highly conserved and structurally similar evolution of BZR family. • Homologous genes PtBZR9 and PtBZR12 exhibited mutual interaction and binding to the E-box elements. • Transgenic plants of PtBZR9 and PtBZR12 plants exhibited strong drought tolerance. • PtBZR9 and PtBZR12 may be involved in the BR signaling pathway for regulate drought stress. [ABSTRACT FROM AUTHOR]

Introduction: Takotsubo cardiomyopathy (TTC), also known as stress‐induced cardiomyopathy, resembles acute heart failure syndrome but lacks disease‐specific diagnosis and treatment strategies. TTC accounts for approximately 5–6% of all suspected cases of acute coronary syndrome in women. At present, animal models of TTC are often created by large amounts of exogenous catecholamines such as isoproterenol. However, isoproterenol injection cannot fully simulate the onset of stress‐induced cardiomyopathy in humans since stress is not an instantaneous event. Methods: Rats were immobilized for 6 h per day for 1–14 days. To examine whether the TTC model was successful, echocardiography was employed; Elisa detected serum sympathetic activation markers; and the Open‐Field test (OFT) was used to analyze behavioral changes in rats after stress. Western blot and histology were used to assess sympathetic remodeling, inflammation levels, and fibrosis; qRT‐PCR was used to explore the levels of fibrosis and myocardial hypertrophy. The electrical stability of ventricular was determined by electrophysiological testing. Results: The rats showed severe stress behavior and local sympathetic remodeling of the heart after only 1 day of stress. After 3 days of stress, the induction of ventricular tachyarrhythmia increased prominently. The highest incidence of TTC in rats was at 5 days of immobilization stress. The pathological left ventricular remodeling caused by immobilization (IMO) stress includes inflammatory infiltration, fibrosis, and myocardial hypertrophy. Conclusions: Our study confirms the hypothesis that IMO stress can mimic Takotsubo cardiomyopathy, and the various effects on the heart depending on the duration of IMO stress. We observed the highest incidence of TTC occurred after 5 days of stress. Furthermore, there is a gradual occurrence of electrical and structural remodeling as the stress duration prolongs. [ABSTRACT FROM AUTHOR]

Analysis of complex biological functions usually requires tissue-specific genetic manipulations in multicellular organisms. The C. elegans germline plays regulatory roles not only in reproduction, but also in metabolism, stress response and ageing. Previous studies have used mutants of rrf-1, which encodes an RNA-directed RNA polymerase, as a germline-specific RNAi tool. However, the rrf-1 mutants showed RNAi activities in somatic tissues. Here we constructed a germline-specific RNAi strain by combining an indel mutation of rde-1, which encodes an Argonaute protein that functions cell autonomously to ensure RNAi efficiency, and a single copy rde-1 transgene driven by the sun-1 germline-specific promoter. The germline RNAi efficiency and specificity are confirmed by RNAi phenocopy of known mutations, knockdown of GFP reporter expression, as well as quantitative RT-PCR measurement of tissue-specific mRNAs upon RNAi knockdown. The germline-specific RNAi strain shows no obvious deficiencies in reproduction, lipid accumulation, thermo-tolerance and life span compared to wild-type animals. By screening an RNAi sub-library of phosphatase genes, we identified novel regulators of thermo-tolerance. Together, we have created a useful tool that can facilitate the genetic analysis of germline-specific functions in C. elegans. [ABSTRACT FROM AUTHOR]

In this work, a facile ratiometric fluorescence sensor for GSH measurement was designed based on MnO 2 nanosheet (NS), carbon dots (CDs), as well as a simple substrate o-phenylenediamine (OPD). Herein, MnO 2 NS played triple essential roles in the sensing system. First, it could be reduced by GSH through a special reaction, and therefore served as GSH recognizer. Second, it played as a fluorescence nanoquencher to strongly quench the fluorescence of CDs. Third, it could directly oxidize OPD to yield a luminescent product 2, 3-diaminophenazine (DAP) via the intrinsic oxidase-like activity. It revealed that MnO 2 NS could be reduced to Mn2+ in the presence of GSH. Thus its oxidase-like activity and fluorescence quenching abilities were inhibited, which then restricted the generation of DAP and recovered the fluorescence of CDs. Based on this phenomenon, a novel ratiometric fluorescence sensor for GSH determination was fabricated by measuring the ratio of fluorescent intensity of DAP to that of CDs. Besides, the constructed ratiometric fluorescent sensor, which could be facilely operated with single-wavelength excitation, exhibited high sensitivity and selectivity with a wider linear range and a lower detection limit. Image 1 • A facile single-wavelength excitation ratiometric fluorescence sensor was constructed for GSH. • MnO 2 nanosheets can not only effectively quench the fluorescence of CDs but also oxidize OPD into luminescent DAP due to its intrinsic oxidase-like activity. • DAP could also quench the fluorescence of CDs through the inner filter effect. [ABSTRACT FROM AUTHOR]

In the natural environment, complex and changeable meteorological factors can influence changes in the internal physiology and phenotype of crops. It is important to learn how to convert complex meteorological factor stimuli into plant perception phenotypes when analyzing the biological data obtained under the natural field condition. We restored the true gradation distribution of leaf color, which is also known as the skewed distribution of color scale, and obtained 20 multi-dimensional color gradation skewness-distribution (CGSD) parameters based on the leaf color skewness parameter system. Furthermore, we analyzed the correlation between the five corresponding meteorological factors and canopy CGSD parameters of peppers growing in a greenhouse and cabbages growing in an open air environment, built response model and inversion mode of leaf color to meteorological factors. Based on the analysis, we find a new method for correlating complex environmental problems with multi-dimensional parameters. This study provides a new idea for building a correlation model that uses leaf color as a bridge between meteorological factors and plants internal physiological state. [ABSTRACT FROM AUTHOR]

• An HPLC for detection of purines in prepackaged food was developed. • Physical and chemical methods are simultaneously employed to extract purine. • Purine contents of various prepackaged food were detected. • Data will be helpful to guide the diet and develop hypopurine prepackaged food. A high performance liquid chromatography was established to determine purine content of prepackaged food. Chromatographic separation was performed on Agilent5 TC-C18 column. Ammonium formate (10 mmol/L, pH = 3.385) and methanol (99:1) were used as mobile phase. Purine concentration and peak area showed good linear relationships in the range from 1 to 40 mg/L (guanine, hypoxanthine, adenine) and xanthine exhibited a good linear relationship ranged from 0.1 to 4.0 mg/L. Recoveries of four purines ranged from 93.03% to 107.42%. Purine content in prepackaged food was following: animal derived prepackaged food: 16.13–90.18 mg/100 g; beans and bean products: 66.36–157.11 mg/100 g; fruits and fruit products: 5.64–21.79 mg/100 g; instant rice and flour products: 5.68–30.83 mg/100 g; fungi, algae, fungi and algae products: 32.57–70.59 mg/100 g. This proposed method had good precision and accuracy with a wide linear range for detection of purine. Animal derived prepackaged food was purine-rich food, purine content of plant derived prepackaged food varied greatly. [ABSTRACT FROM AUTHOR]

Abstract Herein, a label-free and double recognition–amplification (LDRA) strategy for carcinoembryonic antigen (CEA) detection was developed, based on a new designed dual-function messenger probe (DMP) coalescing with DNA tetrahedron probes (DTPs) and hybridization chain reaction (HCR). The DMP possess dual-function to replace CEA for specific interface hybridization and initiate hybridization chain reaction. The interfacial hybridization event was quantitatively converted to an electrochemical signal by using hemin/G-quadruplex (h-Gx) formed after the hybridization chain reaction. Self-assembled DNA tetrahedron probes, which were readily decorated on an electrode surface as a scaffold with rigid support and ordered orientation, enabled the highly efficient strands hybridization and greatly increased target accessibility as well as significantly decreased noise. The proposed assay integrated dual recognition processes and HCR signal amplification processes, achieving the identification of low concentration of CEA as detection limit of 18.2 fg mL−1 (S/N = 3) and wider linearity range of 0.0001 ng mL−1–50 ng mL−1. A new electrochemical sensing method was proposed for CEA detection and used in real clinical samples. The obtained results were good consistency with those of clinical diagnosis. Highlights • A new dual-function messenger probe (DMP) was designed for specific interface hybridization and initiate HCR. • The employment of DNA tetrahedron probes increased the probability of hybridization and reduced the background signal. • The synergetic combination of DMP and hybridization chain reaction (HCR) improved the sensitivity of the detection. • The proposed strategy was used to analysis CEA in real sample and achieved a detection limit as low as 18.2 fg/mL. [ABSTRACT FROM AUTHOR]

A novel electrochemically activated nanocomposite, CoS 2 Nanoparticles and MoS 2 Nanosheets decorated poly(diallyldimethylammonium chloride)-functionalized graphene (CoS 2 -MoS 2 -PDDA-GR), was successfully synthesized through a simple and low-cost method. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Electrochemical impedance spectroscopy (EIS) and Cyclic voltammetry (CV) techniques were used to characterize the nanocomposites. Based on the CoS 2 -MoS 2 -PDDA-GR nanocomposite modified glassy carbon electrode, the electrochemical properties of eriocitrin were investigated in detail and a sensitive determinative method was established synchronously. Compared with others, this sensor exhibited larger effective surface area, more reactive site and excellent voltammetric response for eriocitrin. Under optimum conditions by DPV, the oxidation peak currents responded to eriocitrin linearly over a concentration range from 2.0 × 10 −9 to 1.0 × 10 −6 mol L −1 with a detection limit of 6.7 × 10 −10 mol L −1 (S/N = 3). In addition, this fabricated sensor was successfully applied to detect eriocitrin in real samples with satisfactory results. [ABSTRACT FROM AUTHOR]

Kenaf is one of the most important natural cannabis plants. Molecular marker-assisted breeding is vital for accelerating the breeding process of kenaf. However, the number of kenaf markers is insufficient for molecular marker-assisted breeding. Using transcriptome sequencing data for salt-stressed kenaf plants, the number and distribution of simple sequence repeats (SSRs) and single nucleotide variations (SNVs) in the expressed sequences were determined. The objectives of this study were to elucidate the sequence variations in kenaf genes expressed in response to salt stress and to identify stable and dependable molecular markers. Primers were designed for SSR loci and then EST-SSR molecular markers were generated. The subsequent analyses revealed that 30.50% of the unigenes contained SSR motifs, most of which were single nucleotides followed by trinucleotides and dinucleotides. The unigenes containing SSRs were mostly associated with kenaf salt tolerance. Additionally, 10,483 SNVs were detected in contig sequences. Of the 3995 differentially expressed genes encoding interacting proteins, 1297 contained SSRs. Most of these genes were associated with metabolic pathways (e.g., 03000 transcription factors, B09132 signal transduction, and 04122 sulfur relay system). We designed 20 pairs of EST-SSR primers to genotype 30 kenaf varieties (lines), of which 9 primer pairs were ideal for genotyping (e.g., 1 highly polymorphic marker and 2 moderately polymorphic markers). The primer pairs designed for the EST-SSR markers in the kenaf genome may be useful SSR molecular markers for future research on kenaf. The verified polymorphic markers may be applicable to the molecular marker-assisted breeding of salt-tolerant kenaf varieties. [ABSTRACT FROM AUTHOR]

WRKY gene family is one of the largest transcription factor families involved in various physiological processes of plants. Flax (Linum usitatissimum) is an important stem fiber crop, and it is also an economically important crop in natural fiber and textile industries around the world. In this study, 105 WRKY genes were obtained by screening the whole genome of flax. There were 26 in group I, 68 in group II, 8 in group III and 3 in group UN. The characteristics of the WRKY motif and gene structure in each group are similar. The promoter sequence of WRKY genes includes photoresponsive elements, core regulatory elements and 12 cis-acting elements under abiotic stress. Similar to A. thaliana and Compositae plants, WRKY genes are evenly distributed on each chromosome, with segmental and tandem repeated events, which play a major role in the evolution of WRKY genes. The flax WRKY gene family is mainly concentrated in group I and group II. This study is mainly based on genome-wide information to classify and analyze the flax WRKY gene family, laying a foundation for further understanding the role of WRKY transcription factors in species evolution and functional analysis. [ABSTRACT FROM AUTHOR]

• Root exudates increased soil pH while decreased soil redox potential (Eh); • Root exudates increased arsenite (As(III)) and arsenate (As(V)) concentrations in soil porewater and had an obvious dose effect; • Root exudates enhance the relative abundance of Fe(III)-reducing bacteria Geobacter and Anaeromyxobacter. Root exudates are crucial for plants returning organic matter to soils, which is assumed to be a major source of carbon for the soil microbial community. This study investigated the influence of root exudates on the fate of arsenic (As) with a lab simulation experiment. Our findings suggested that root exudates had a dose effect on the soil physicochemical properties, As speciation transformation and the microbial community structure at different concentrations. The addition of root exudates increased the soil pH while decreased the soil redox potential (Eh). These changes in the soil pH and Eh increased As and ferrous (Fe(II)) concentrations in soil porewater. Results showed that 40 mg/L exudates addition significantly increased arsenite (As(III)) and arsenate (As(V)) by 541 and 10 times respectively within 30 days in soil porewater. The relative abundance of Fe(III)-reducing bacteria Geobacter and Anaeromyxobacter increased with the addition of root exudates, which enhanced microbial Fe reduction. Together these results suggest that investigating how root exudates affect the mobility and transformation of As in paddy soils is helpful to systematically understand the biogeochemical cycle of As in soil-rice system, which is of great significance for reducing the health risk of soil As contamination. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, we developed a high-performance electrochemical aptasensor for the detection of carcinoembryonic antigen (CEA) using highly active peptide-conjugated hemin/G-quadruplex (hGQ-peptide) and porous Pd nanoparticles (PdNPs). Of note, the hGQ-peptide showed an enhanced catalytic activity as compared to the unmodified hGQ, and thus served as efficient electrocatalyst in this biosensor. Porous PdNPs acted as supported matrixes for high immobilization of hGQ-peptide hybrids, aptamer, redox-active toluidine blue (Tb) and alcohol dehydrogenase (ADH), resulting in the formation of ADH/Tb/hGQ-peptide/aptamer/PdNPs as the proposed bioprobes. Upon the sandwich-type specific reaction between aptamer and CEA, the bioprobe was presented on the sensing interface. Highly effective signal amplification could be then achieved by the bioprobe catalyzed cascade enzymatic reaction. Compared with the original hGQ, the hGQ-peptide yielded more than 2-fold improvement in signal amplification because of the peptide-enhanced catalysis. Therefore, the designed aptasensor displayed a wide linear range from 0.0001 to 100 ng mL −1 with a lower detection limit of 20 fg mL −1 for CEA determination, presenting the better analytical performance as compared to the relevant prior biosensors. This work further expanded the application of hGQ DNAzyme in biosensor. With the good anti-interference ability and selectivity, the proposed electrochemical aptasensor held great promise for ultrasensitive detection of other proteins in clinical diagnosis. [ABSTRACT FROM AUTHOR]

Arctigenin was determinated by an electrochemical method for the first time based on a novel voltammetric sensor, which was prepared by simple dipping-drying of SWCNTs on glassy carbon electrode (GCE) initially and then electrochemical deposition of Iodide. The resulting Iodide/SWCNTs/GCE displayed a significant voltammetric response to arctigenin due to the electrocatalytic ability of Iodide for arctigenin and a large specific surface area, excellent electric conductivity of SWCNTs. Meanwhile, the redox mechanism of arctigenin on Iodide/SWCNTs/GCE was also studied. The wide linear range of 3 × 10 − 8 mol L − 1 to 5 × 10 − 6 mol L − 1 and low detection limit of 1 × 10 − 8 mol L − 1 for the determination of arctigenin were achieved together with high sensitivity, selectivity, good stability. To examine the practical analytical utility of the proposed electrode, the real sample Fructus Arctii was examined and the result was found satisfactory. [ABSTRACT FROM AUTHOR]

A novel voltammetric sensor was constructed by simple dripping single-walled carbon nanotubes (SWCNTs) on to the glass carbon electrode (GCE) firstly and electro-polymerizing l -Citrulline film subsequently. The resulting poly( l -Citrulline)/SWCNTs/GCE showed a significant voltammetric response to picroside II due to the synergistic effect of SWCNTs and poly( l -Citrulline) film. The first electroanalytical method of picroside II was proposed with detection linear range from 8.0×10 −8 to 5.0×10 −6 mol L −1 and a detection limit of 3×10 −8 mol L −1 .The high sensitivity, selectivity and long-term stability made the sensor suitable for the determination of picroside II. Moreover, based on the systematically investigation and some kinetics parameters calculated in the experimentation, the reaction mechanism of picroside II at the poly( l -Citrulline)/SWCNTs modified GCE was obtained reliably. Lastly, the proposed sensor was used for the determination of picroside II in real sample with satisfactory results. This work promoted the potential applications of amino acid materials and SWCNTs in electro-chemical sensors. [ABSTRACT FROM AUTHOR]

In this study, high-entropy spinel (FeCoNiMnAl) 3 O 4 catalyst with a three-dimensional(3D) layered microflower structure assembled by nanosheets grown on Ni foam (NF) is synthesized for stable seawater oxidation. Density functional theory (DFT) calculations indicate that it has a strong charge transfer capability, thereby reducing the energy barrier and boosting the reaction. As a result, a low oxygen evolution reaction (OER) overpotential of 274 mV@50 mA cm−2 is achieved with a small Tafel slope of 47.79 mV dec−1 in 1 M KOH solution. Notably, DFT calculations further verify that it shows stronger adsorption of OH than Cl. As expected, the required overpotentials are still as low as 284 and 295 mV@50 mA cm−2 in alkaline simulated seawater and natural seawater electrolytes. Also, it exhibits excellent stability and corrosion resistance, maintaining stable OER activity over 50 h at 500 mA cm−2 in alkaline natural seawater, which has the potential to realize industrial electrochemical seawater splitting. [Display omitted] • A high-entropy spinel (FeCoNiMnAl) 3 O 4 catalyst is obtained for seawater oxidation. • The catalyst exhibits low OER overpotential of 295 mV@ 50 mA cm−2 in seawater electrolyte. • The catalyst displays long-term stability in alkaline seawater electrolyte. • DFT calculations verify strong synergistic effect with stronger adsorption of OH than Cl. • The driven voltage of assembled electrolyzer by using the catalyst is 1.6 V at 80 °C. [ABSTRACT FROM AUTHOR]

• P-type CuInS 2 microflower recombined rGO modified ITO was used as photocathode. • Target was recognized by triple helix DNA switch in homogeneous solution. • Ferrocene labeled single stranded DNA was released as signal probe. • Energy level matching between ferrocene and CuInS 2 leaded an enhanced photocurrent. A sensitive signal-on photoelectrochemical aptasensor for antibiotic determination was constructed based on the energy level matching between ferrocene and CuInS 2. P-type CuInS 2 microflower was complexed with reduced graphene oxide (CuInS 2 /rGO) to get photocathode current with good photoelectric conversion efficiency and stability. Then, hairpin DNA (HP) was covalently bonded to the electrode surface. A triple helix DNA (THMS) was used as a molecular switch. After the specific recognition between target and THMS in homogeneous solution, ferrocene labeled probe (Fc-T2) was released. Finally, Fc-T2 was captured by the HP, which leaded the obvious increase of photocurrent for the energy level matching between ferrocene and CuInS 2. The increase of the photocurrent signal was proportional to the concentration of target amoxicillin (AMOX), the linear range was 100 fM-100 nM with detection limit of 19.57 fM. Meanwhile, the method has been successfully applied for milk and lake water samples analysis with satisfactory results. [ABSTRACT FROM AUTHOR]

Various nucleic acid molecular machines have emerged in recent years. However, when the nucleic acid tracks are fully depleted, these walkers are highly susceptible to premature release or stalling in regions where the tracks are locally exhausted. In this work, a molecular walking machine with a cleat domain preventing dissociation from the track was explored for ultrasensitive detection of miRNA. It has been verified that the cleat design can enhance the signal amplification efficiency of molecular walking machines for electrochemical miRNA-141 detection. Notably, the single-step electrochemical biosensing platform utilizing the cleat-equipped molecular walking machine (CMWM) is exceptionally straightforward and rapid, concluding the reaction within 90 min and achieving a remarkable low detection limit of 0.26 fM. The proposed molecular walking machine with this specific cleat structure was utilized for the identification of miRNA-141 in cellular lysates, exhibiting remarkable selectivity and consistent reproducibility, showcasing its effective utility in bioanalysis. Therefore, the cleat walker developed in this study introduces an innovative method for constructing a miRNA electrochemical biosensing platform, offering new perspectives for its application in biomolecule detection and clinical disease diagnosis. A rapid one-step electrochemical method based on cleat-equipped molecular walking machine. [Display omitted] • The cleat DNA walker was successfully designed for miRNA-141 detection. • The cleat design was first applied in nuclease-powered DNA walker. • The cleat strategy can enhance the signal amplification efficiency of DNA walkers. • The proposed one-step method takes only 90 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probes were prepared by integrating the dual-enzyme catalytic activity of CuO NPs and luminescent of Ln ICPs via facile self-assembly. • The self-cascade nanoenzyme activity of CuO nanoparticles was significantly enhanced upon encapsulated into Ln ICPs. • A versatile ratiometric platform for ultrahigh selective and sensitive detection of GSH was established. Tandem enzyme can catalyze some cascade reactions with high efficiency, and some few tandem enzyme-like mimics have been discovered recently. Further improving the catalytic efficiency of tandem nanoenzymes with facile method may undoubtedly promote and broaden their applications in various fields. In this work, cupric oxide nanoparticles (CuO NPs) with dual-functional enzyme mimics were synthesized using the rapid deposition method in advance, which simultaneously combined with lanthanide infinite coordination polymers (Ln ICPs) during the self-assemble of Tb3+, guanine-5′-triphosphate (GTP) and auxiliary ligand terephthalic acid (TA). Excitingly, the obtained Tb-GTP/TA@CuO ICPs, not only displayed obviously enhanced tandem catalytic activity compared with pure CuO NPs, but also provided a versatile ratiometric platform for ultrahigh selective and sensitive detection of glutathione (GSH) under single-wavelength excitation. A good linear relationship between the ratio signal and the GSH concentration was spanning from 0.001 to 20 μM with an impressive detection limit of 0.50 nM. This study opens a new and universal avenue for preparing integrated multifunctional probes by coupling of nanoenzyme catalytic activity with superior luminescent Ln ICPs through facile method. [ABSTRACT FROM AUTHOR]

Sensitive and selective analysis of low content nucleic acid sequences plays an important role in pathogen analysis, disease diagnosis and biomedicine. The electrochemical biosensor based on toehold-mediated strand displacement reaction (TMSD) is highly attractive in nucleic acid detection due to their improved sensitivity and rapid response. But the traditional TMSD carried out on the electrode always with low displacement efficiency and complicated electrode operation, resulting in compromised sensing performance. There is a great need to construct a novel TMSD based electrochemical detection strategy to overcome such challenges in nucleic acid detecting. Herein, a triple signal amplification electrochemical aptasensor was developed for ultrasensitive detection of CYFRA21-1 DNA. The dual-output toehold mediated strand displacement reaction (dTMSD) can convert one input to two strands output within one strand displacement cycle. So that it possesses a higher efficiency for improving the sensitivity in comparison with the single-output TMSD. And the fuel strand was configured with a tail to realize successive DNA circuits through self-propelling as a DNA walker. All the above processes were carried out on magnetic beads, which is conducive to achieving effective sample purification and minimizing the background signals. Besides, Exonuclease III was further amplified signal. As a result, through the cascade use of above three technologies, the proposed biosensing strategy realized sensitive detection of target DNA with a low detection limit of 0.35 fM (S/N = 3) and wide linear range (0.5 fM-500 pM). The proposed novel dTMSD combining multiple signal amplification strategies for electrochemical detection of CYFRA21-1 DNA with easy operation not only possesses excellent sensitivity and selectivity, but also has potential application value for monitoring DNA in serum. Meanwhile, the development of highly sensitive and specific CYFRA21-1 DNA detection methods is very important for the prevention and treatment of lung cancer. Schematic illustration of the electrochemical aptasensor based on cascade signal amplification strategy. [Display omitted] • Dual-output toehold mediated strand displacement reaction (dTMSD) effectively increased the output of messenger probe. • Fuel strand-powered DNA walker further catalyzed target DNA circuits. • The dTMSD was undergone on magnetic beads can effectively purify the sample, reduce the background interference. • Exo III realized the recycling of the messenger probe and further enlarged the signal responds. • Ultrasensitive detection for target DNA was achieved by cascade signal amplification strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiCoMnS/rGO was synthesized by one-step hydrothermal method. • NiCoMnS/rGO nanocomposite showed good peroxidase-like activity. • NiCoMnS/rGO/GCE can catalyze H 2 O 2 reduction and glucose oxidation. It is attractive to develop non-noble-metal nanomaterials with large surface area and good conductivity as a high-active catalyst electrode for molecular detection in electrochemical sensors. In this work, we successfully fabricated NiCoMnS/rGO by one-step hydrothermal method, which showed good peroxidase-like activity in an acidic environment. The NiCoMnS/rGO modified electrode exhibited excellent enzyme-free electrochemical catalysis performance for hydrogen peroxide (H 2 O 2) reduction in acidic solutions and glucose oxidation in alkaline solutions. For the detection of H 2 O 2 , this electrochemical sensor displayed a wide linear range from 10.0 μM to 7.5 mM with a low limit of detection of 1.1 μM. As for glucose, it also showed a wide linear range from 50.0 μM to 1.3 mM with a low limit of detection of 1.0 μM. Moreover, it had good stability and reproducibility. It was also used for the determination of H 2 O 2 and glucose in real samples. This nanomaterial held great promise as an enzyme-free sensing platform toward H 2 O 2 and glucose detection. [ABSTRACT FROM AUTHOR]

Design and fabrication of integrated multifunctional probes with intrinsic catalytic and detection abilities is of great importance to simplify the operation in biosensing application with high sensitivity. Herein, dual-emitting lanthanide coordination polymers (Ln-CPs) were facilely prepared by self-assembly of guanine diphosphate (GDP), terephthalic acid (TA), Tb3+ and Cu2+ designated as Tb/Cu-GDP/TA CPs. The doped Cu2+ endowed CPs with obviously enhanced peroxidase mimicking activity compared with free Cu2+. In the presence of H2O2, the probe catalyzed the oxidation of TA generating a new blue fluorescent product, while the fluorescence of Tb3+ decreased simultaneously. Therefore, a new sensitive ratiometric fluorescent sensor for H2O2 has been developed with a good linear range from 0.01 to 300 μM and limit of 1.62 nM. Moreover, the proposed platform could be extended to GSH ratiometric assay in the presence of H2O2, and interestingly, the detection performance could be easily adjusted by adding different concentration of H2O2. This work will facilitate the development of luminescent nanoenzymes based on Ln-CPs to construct the simple ratiomatric sensing platform. [ABSTRACT FROM AUTHOR]

• Triplex DNA molecular switch recognize different targets and release the same probe molecular. • CuInS 2 /rGO was used to enhance the photocurrent signal. • A universal photoelectrochemical aptasensor was constructed for antibiotic highly selective and sensitive detection. In this work, a universal and convenient photoelectrochemical (PEC) biosensor was proposed to detect antibiotic on the basis of CuInS 2 /rGO and triplex DNA molecular switch. High performance photoactive structure was formed via p-type CuInS 2 nanosphere complexed with rGO, which was employed to enhance the cathode photocurrent. Capture probe (CP) was conjugated onto the photoactive interface through covalent bonding. In the absence of target, the triplex DNA (THMS) was in a closed state. After introducing a target, the interaction between the target and the specific ring part DNA fragment leaded to the dissociation of the THMS and thereby liberated the single strand DNA (SP). The above identification process was completed in the homogeneous solution. Then, SP was captured to the electrode by CP and hybridized to form dsDNA. The steric effect of dsDNA hindered the interfacial charge transfer, resulting in signal-off photocurrent output. By only altering the specific loop section sequence of THMS, different targets can release the same SP, and can be detected on the same sensing platform under the same testing conditions. As proof of principle, three kinds of antibiotics amoxicillin (AMOX), ampicillin (AMP) and tobramycin (TOB) was detected, achieving limit of detection values of 3.17 pM, 0.63 nM and 2.81 fM, respectively. This approach was also used to detect antibiotic residues in food and environmental samples, which provides a promising paradigm for developing universal, high-performance and convenient PEC biosensing platform. [ABSTRACT FROM AUTHOR]

Complexing with adenosine-5′-monophosphate (AMP) was proven to be a facile way to enhance the oxidase-mimicking activity of Ce4+, and enabled nanoenzyme recovery and reuse. Additionally, the oxidase-mimicking activity of AMP-Ce4+ infinite coordination polymers (ICPs) could be specifically inhibited by Fe2+. Based on this finding, we developed a simple and highly selective colorimetric assay to detect Fe2+. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuO NSs@Au NFs was used to provide strong cathode current and binding site for aptamer. • Specific binding effect of aptamer and target improved selectivity of the sensor. • The sensor with a wide linear range of 5 pM-300 nM and a low detection limit of 49.9 fM. A signal off type photoelectrochemical (PEC) aptasensor was constructed for the sensitive detection of chloramphenicol based on CuO nanosheets (CuO NSs) and gold nanoflowers (Au NFs) modified indium tin oxide (ITO) electrode. CuO NSs was p-type photoactive semiconductor materials, which had narrow band gap and high absorption rate of visible light. After combining with Au NFs, the composite CuO NSs@Au NFs produced a strong cathodic photocurrent for the excellent electron conductivity, large specific surface area and Surface Plasmon Resonance effect (SPR) of Au NFs. At the same time, Au NFs provided a binding site for aptamer, which greatly improved the sensitivity of the constructed sensing platform. After the target chloramphenicol (CAP) was specifically captured by the aptamers on the electrode, the formed bioconjugates seriously hindered the transfer of electrons and the absorption of light and caused a reduced photocurrent. For the detection of CAP, this signal off type PEC aptasensor had a linear range of 5 pM-300 nM and a limit of detection of 49.9 fM (S/N = 3) with good stability, selectivity and reproducibility. Meanwhile, the method had satisfactory recovery results in the detection of CAP in real-life samples such as milk, tap water, honey and chloramphenicol eye drops. [ABSTRACT FROM AUTHOR]

Rapid and effective diagnosis of communicable disease is one of the critical issues of the modern society, especially for detecting different targets at the same time. In this work, a grafting homogenous electrochemical biosensing strategy is proposed by integrating of reverse proximity ligation and exonuclease III (Exo III) assisted target circulation to analyze hepatitis B (HBV) and human immunodeficiency (HIV). Specially, a two-wing nanodevice (TWD) with two detection paths is elaborately designed based on analogous proximity ligation assay. The reverse proximity ligation process provides a new way of signal conversion and amplification, what accomplished by demolishing the TWD in the presence of targets. Meanwhile, a vast number of signal probes are released via Exo III assisted target circulation. Then the signal probes are grafted on the universal sensing interface, which is decorated with graftable tetrahedron DNA (GTD). These lead to a highly amplified electrochemical signal. Compared with the conventional strategies, the grafting homogenous electrochemical biosensing strategy not only achieves convenient sensitive detection of multiple communicable diseases DNA simultaneously, but also performs well in the detection of sole target. This strategy effectively decreases the background, homogenizes the distribution of probes, and avoids the complex and time-consuming modification process of the working electrode, which holds great potential application in early diagnosis for communicable disease in the future. • A two wing nanodevice is constructed by using the principle of analogous proximity ligation assay. • By using the principle of reverse proximity ligation assay, a new manner for conversing and amplifying the electrochemical signal is demonstrated for the first time. • The graftable tetrahedron DNA is immobilized on the electrode to construct a universal grafting sensing interface. • This strategy can be used to detect multiple targets simultaneously, and can also perform well in detection of sole target. [ABSTRACT FROM AUTHOR]

Herein, a robust and highly ordered three-dimensional electrochemical DNA (3D E-DNA) biosensor was proposed, and its orientation was controlled from top down by poly adenine oligonucleotides (polyA-ODNs)-mediated rolling motor (PRM) and graftable tetrahedron DNA (GTD). The GTD with a grafting domain was immobilized on the electrode surface to construct a well-organized sensing interface and controlled the orientation and distribution of the whole system at the "bottom" of this biosensor. The polyA-ODNs regulated the direction and density of the leg DNA attached on PRM at the "top" of the biosensor. The motion was achieved through the target induced cyclic cleaving, which triggered the motor rolling rather than walk. Impressively, the duplex strand DNA (dsDNA) formed after grafting, as a girder, provided a stable support to the soft long single strand (ssDNA), which facilitated the formation of the catalytic center, elevated the efficiency of the rolling cleavage. Under the optimal conditions, the designed biosensor exhibited a lower limit of 0.17 nM and wide linear range from 0.5 nM to 1.5 μM for adenosine rapid detection. Unique dual orientation regulated characteristics of the system increased the probability hybridization enormously and improved the motion efficiency significantly, which offered new avenue of DNA nanomachines development in biosensor platform. • The 3D electrochemical DNA biosensor is highly ordered with the density and orientation are well controlled from top down. • The rolling motor is well-designed and triggered rolling by target induced cyclic cleaving. • A distinctive graftable tetrahedron DNA is proposed to constructed 3D sensing surface regulated the density of the whole system. • The graftable tetrahedron can be used to simultaneously construct different sensing strategies without re-synthesizing according to the target. • Poly adenine prompts the substrate DNA of rolling motor to adopt an upright conformation and program the direction and density of substrate DNA precisely. [ABSTRACT FROM AUTHOR]

In this work, a dual amplified signal enhancement approach based on coupling deoxyribozyme (DNAzyme)-driven bipedal DNA walkers (BDW) and terminal deoxynucleotidyl transferase (TdT)-mediated DNA elongation signal amplifications has been developed for highly sensitive and label-free electrochemical detection of thrombin in human serums. In presence of thrombin, the BDW complex, which is comprised from the target thrombin and two DNAzyme-containing probes, can exhibit autonomous cleavage behavior on the surface of the substrate DNA (SD) modified electrode, and remove the cleaved DNA fragment from the electrode surface. Subsequently, the TdT can catalyze the elongation of the SD with free 3′-OH termini and formation of many G-quadruplex sequence replicates with the presence of 2′-deoxyaguanosine-5′-triphosphate (dGTP) and adenosine 5′-triphosphate (dATP) at a molar ratio of 6:4. These G-quadruplex sequences bind hemin and generate drastically amplified current response for sensitive detection of thrombin in a "signal-on" and completely label-free fashion. Under optimized conditions, the response peak current was linear with the concentration of thrombin in the range from 0.5 pM to 100000 pM with detection limit of 0.31 pM. This research provides us a sustainable idea for the hyphenated multiple amplification strategies and a stable and effective method for the detection of protein biomarkers. Image 1 • A new electrochemical biosensor was developed based on dual cascade amplification strategy of DNAzyme-driven bipedal DNA walkers. • The developed electrochemical biosensor was completely label-free in a "signal-on" fashion. • The work proves the possibility of the strategy based on DNA machine hyphenating diversified amplification methods. [ABSTRACT FROM AUTHOR]

A label-free electrochemical aptasensor was developed for the sensitive detection of interferon-gamma (IFN-γ). To do this, a diblock dual-aptamer allosteric hairpin (DDAH) was designed, followed by conjugation with gold nanoparticles (DDAH&AuNP). The presence of target destroyed the stable hairpin structure, and then the catalytic cleavage of DNAzymes removed the IFN-γ-binding molecules, triggering the allosteric switching from inactive hairpin to active streptavidin aptamer (A-DDAH&AuNP) in homogeneous system. Moreover, streptavidin-inorganic hybrid nanoflowers decorated with graphene composites (SFG) were synthesized and used as substrates to modify glassy carbon electrodes (SFG/GCE). SFG specifically bind to the A-DDAH&AuNP to realize high-efficient readout of signals. Under the optimal conditions and by using differential pulse stripping voltammetry (DPSV), the response peak currents increases linearly with the logarithm of the IFN-γ concentration in the range between 0.1 pg mL−1 and 500 ng/mL. The detection limit is as low as 19 fg mL−1. The aptasensor also has excellent electrochemical performances, which exhibits broad application prospects in biometric analysis. Image 1 • A new diblock dual-aptamer allosteric hairpin switch is designed and used to improve the sensitivity and selectivity of aptasensor. • SFG was used as substrate material to amplify the signal of sensor. • The electrochemical aptasensor showed a low detection limit of 19 fg mL−1 for IFN-γ. [ABSTRACT FROM AUTHOR]

Herein, a signal-on electrochemical aptasensor for highly sensitive detection of thrombin (TB) was constructed based on the DNAzyme-driven DNA walker strategy. We developed a new dual functional hairpin DNA (HP) containing a substrate sequence of the Mg2+-dependent DNAzyme (in the loop region) and the G-quadruplex forming segment (in the stem region). The DNA walker (TBA 2 -DWs), containing a TB aptamer and an enzymatic sequence, was introduced onto gold electrode (GE) by aptamers-target specific recognition, and thus initiated the enzymatic sequences to hybridize with the substrate sequence. Then, the DNA walker could repeatedly bind and cleave HP in the assistance of Mg2+, unlocking many active G-quadruplex forming sequences. Finally, hemin can further bind the G-quadruplex to form G-quadruplex/hemin complexes and generate enhanced current output. The aptasensor for TB assay showed a linear detection range from 1 pM to 60000 pM with a lower detection limit of 0.58 pM. And more, the proposed detection strategy was enzyme-free and label-free. Image 1 • A signal-on electrochemical aptasensor based on DNAzyme-driven DNA Walker strategy has been developed. • DNA walker is driven by DNAzyme and induced by dual recognition of target molecules. • A new dual functional hairpin DNA (HP) was developed and used in this electrochemical anpptsensor. • A signal-on electrochemical aptasensor is designed from enzyme-free and label-free. [ABSTRACT FROM AUTHOR]

Due to widespread application of chlorpyrifos for controlling pests in agriculture, the continuous accumulation of chlorpyrifos residue has caused serious environmental pollution.The detection of chlorpyrifos is of great significance for humans and environment because it can arise a series of diseases by inhibiting acetylcholinesterase (AChE) activity. Photoelectrochemical sensing, as an emerging sensing technology, has great potential in the detection of chlorpyrifos. It is urgent that find a suitable photoelectric sensing strategy to effectively monitor chlorpyrifos. Herein, an n-n heterojunction was constructed by uniformly immobilizing n-type 3DBiOI, which had loose porous structure composed of numerous small and thin nanosheets, on the surface of TiO 2 with anatase/rutile (AR-TiO 2) heterophase junction. Under light irradiation, the proposed BiOI/AR-TiO 2 n-n heterojunction exhibited excellent optical absorption characteristics and photoelectrochemical activity. Additionally, the photoelectrochemical sensing platform demonstrated excellent analytical performance in monitoring chlorpyrifos. Under optimized conditions, it showed a wide detection range of 1 pg mL−1- 200 ng mL−1 and a detection limit (S/N = 3) as low as 0.24 pg mL−1, with superior selectivity and stability. The ultra-sensitivity and great specificity for detection of chlorpyrifos can be ascribed to chelation between Bi (Ⅲ) and C=N and P=S bonds in chlorpyrifos, which had been confirmed in this work. Meanwhile, the PEC sensor also had potential application value for monitoring chlorpyrifos in water samples, lettuce and pitaya, which the recoveries of samples ranged from 96.9% to 104.7% with a relative standard deviation (RSD) of 1.11%–5.93%. This sensor provided a novel idea for constructing heterojunctions with high photoelectric conversion efficiency and had a high application prospect for the detection of chlorpyrifos and other structural analogues. [Display omitted] • A novel BiOI/AR-TiO 2 n-n heterojunction was proposed by two-step drop-coated method. • Both AR-TiO 2 and n-type 3DBiOI had superior photoelectric conversion efficiency. • Synergistic effect of AR-TiO 2 and BiOI ensured the excellent performance of sensor. • The chelation of Bi-chlorpyrifos complex gave the sensor excellent selectivity. • This PEC sensor had good recovery results in the analysis of real samples. [ABSTRACT FROM AUTHOR]

Abstract This work proposes a quenched photoelectrochemical sensing method for highly selective and sensitive detection of protein via Energy Transfer (ET) effect between the AuNPs and CdS:Mn quantum dots. This detection was performed on a sandwich-type aptamer sensing interface. Chitosan modified CdS:Mn/TiO 2 /ITO electrode was used to immobilize capture DNA (S1) via -CONH- bond. In the presence of target protein, AuNPs labeled DNA (AuNPs-S2) was further bonded to the protein to fabricate sandwich sensing platform, which forced the AuNPs away from the electrode surface. In this state, the photocurrent was greatly depressed, mainly due to two factors: (a) the ET effect produced by interparticle distance between CdS:Mn and AuNPs; (b) the steric hindrance of AuNPs-S2 partly obstructs the diffusion of the electron donor. The photocurrent decreased with the increasing concentration of the target protein. Using thrombin as a target, this sensitized method showed a detectable range of 0.1 pM to 8 nM and a detection limit of 30 fM. It possessed high selectivity and good stability for detection of thrombin. This method is extremely flexible and can be extended to varieties of protein targets. Graphical abstract This work proposes a quenched photoelectrochemical sensing method for highly selective and sensitive detection of protein via Energy Transfer (ET) effect between the AuNPs and CdS:Mn quantum dots. The photocurrent decreased with the increasing concentration of the target protein. Using thrombin as a target, It possessed high selectivity and good stability for detection of thrombin. fx1 Highlights • Energy transfer (ET) between CdS:Mn and AuNPs was used to construct Thrombin PEC aptasensor for the first time. • A common and simple Sandwich-type recognition mode was applied to realize the ET effect. • This strategy can be easily extended to develop PEC aptasensors for the sensitive detection of different targets. [ABSTRACT FROM AUTHOR]

Abstract A new nanocomposite, zirconium dioxide nanoparticles decorated poly(diallyldimethylammonium chloride)-functionalized graphene (ZrO 2 -PDDA-Gr), was successfully synthesized through a simple and green method. The simultaneous reduction of grapheme oxide (GO) and formation of ZrO 2 to produce the ZrO 2 -PDDA-Gr had been achieved under hydrothermal conditions. The ZrO 2 -PDDA-Gr showed excellent conductivity and strong adsorption ability toward Diosmin and thus was used to be an excellent probe for electrochemical sensing. The electrochemical characteristics of Diosmin were studied in detail and some dynamics parameters of electrode process were also calculated to discuss the reaction mechanism. Under the optimized conditions, a lower detection limit of 2 × 10−9 mol L−1 (S / N = 3) and a wide linear detection range from 5 × 10−9 to 2 × 10−6 mol L−1 were achieved by differential pulse voltammetry (DPV). Additionally, the proposed electroanalytical methodology was applied in fresh lemon leaves and tablets with satisfactory results, showing that fabricated sensor has potential in application. Highlights • ZrO 2 -PDDA-Gr composite was synthesized using a facile, green and effective one-pot hydrothermal route. • ZrO 2 -PDDA-Gr/GCE sensor has high highly sensitive and excellent selectivity for the determination of Diosmin. • This method can be applied in real sample detection with satisfactory result. [ABSTRACT FROM AUTHOR]