Seasonal drought promotes citrate accumulation in citrus fruit through the CsABF3-activated CsAN1-CsPH8 pathway.

Plenty of rainfall but unevenly seasonal distribution happens regularly in southern China. Seasonal drought from summer to early autumn leads to citrus fruit acidification, but how seasonal drought regulates citrate accumulation remains unknown. Herein, we employed a set of physiological, biochemical, and molecular approaches to reveal that CsABF3 responds to seasonal drought stress and modulates citrate accumulation in citrus fruits by directly regulating CsAN1 and CsPH8. Here, we demonstrated that irreversible acidification of citrus fruits is caused by drought lasting for > 30 d during the fruit enlargement stage. We investigated the transcriptome characteristics of fruits affected by drought and corroborated the pivotal roles of a bHLH transcription factor (CsAN1) and a P3A-ATPase gene (CsPH8) in regulating citrate accumulation in response to drought. Abscisic acid (ABA)-responsive element binding factor 3 (CsABF3) was upregulated by drought in an ABA-dependent manner. CsABF3 activated CsAN1 and CsPH8 expression by directly and specifically binding to the ABA-responsive elements (ABREs) in the promoters and positively regulated citrate accumulation. Taken together, this study sheds new light on the regulatory module ABA-CsABF3-CsAN1-CsPH8 responsible for citrate accumulation under drought stress, which advances our understanding of quality formation of citrus fruit.

Identification of novel benzothiazole derivatives as inhibitors of NEDDylation pathway to inhibit the progression of gastric cancer.

The overexpression of neddylation modification is frequently observed in human tumor cells. Targeting the neddylation pathway has been recognized as a promising anticancer therapeutic strategy, thus discovering potent and selective neddylation inhibitors is of great importance. In this study, we designed and synthesized a series of novel neddylation inhibitors bearing benzothiazole scaffolds by molecular hybridization strategy and all compounds were evaluated for antiproliferative activity against MGC-803, MCF-7, A549 and KYSE-30 cell lines. In vitro anti-tumor studies showed that the most promising compound X-10, effectively suppressed MGC-803 cells growth and migration, induced apoptosis and arrested cell cycle at G2/M phase. Importantly, by directly interacting with NAE1, X-10 blocked NAE1 activity, specifically preventing neddylation of Cullin 3 and Cullin 1, and produced a dose-response decline in the level of UBC12-NEDD8 complex. Overall, our data indicate that X-10 inhibits the process of neddylation, making it a potentially agent for both cancer prevention and therapy purposes.

Embedding Te4+ into Sn4+-Based Metal Halide To Passivate Structure Defects for High-Performance Light-Emitting Application.

Low-dimensional lead-halide hybrids are an emerging class of optical functional material but suffer the problems of toxicity and poor air stability. Among lead-free metal halides, tin(IV)-based metal halides are promising optoelectronic materials due to their robust structure and environmental friendliness. However, their photoluminescence (PL) properties are poor, and the underlying mechanisms are still elusive. Herein, a stable Sn4+-based halide hybrid, (C4H7N2)2SnCl6, was developed, which however exhibits poor PL properties at room temperature (RT) due to the lattice defects and the robust crystal structure. To enhance its PL efficiency, the Te4+ ion with a stereoactive 5s2 lone pair has been introduced into the lattice. As a result, Te4+-doped (C4H7N2)2SnCl6 displays broadband orange emission (∼640 nm) with a PL efficiency of ∼46% at RT. Interestingly, Te4+-doped (C4H7N2)2SnCl6 shows triple emission bands at 80 K, which could be due to the synergistic effect of the organic cations and the self-trapped state induced by Te4+. Additionally, high-performance white light-emitting diodes were prepared using Te4+-doped (C4H7N2)2SnCl6, revealing the potential of this material for lighting applications. This study provides new insight into the PL mechanism of Sn4+-based metal-halide hybrids and thus facilitates the design and development of eco-friendly light-emitting metal halides.

Discovery of the 2,4-disubstituted quinazoline derivative as a novel neddylation inhibitor for tumor therapy.

Overactivation of neddylation has been found in a number of common human tumor-related diseases. In recent years, targeting the neddylation pathway has become an appealing anti-cancer strategy, and it is critical to find neddylation inhibitors with novel structures and higher efficacy. Here, we present the discovery of novel inhibitors of the NEDD8-activating enzyme (NAE) and their antitumor activity in vitro. All synthesized 1,4-disubstituted piperidine compounds were evaluated for antiproliferative activity against MGC-803, MCF-7, A549, and KYSE-30 cells. Among five representative compounds, III-26 bearing a quinazoline motif was identified as the lead one due to the fact that it significantly hindered the neddylation of Cullin1. Cellular mechanisms elucidated that III-26 inhibited the proliferation, migration, and invasion of UBC12-overexpressed MGC-803 cell lines, as well as induced apoptosis and arrested the cell cycle at G2/M phase. Importantly, III-26 reduced NAE activity, thus selectively preventing neddylation of Cullin3 and Cullin1 over other Cullin members. At a dose of 4 µM, III-26 virtually entirely blocked UBC12-NEDD8 conjugation in MGC-803 cells. Our molecular modeling and kinetic investigation suggested that this compound may function as a non-covalent inhibitor of NAE.

[Analysis of ARID1B gene variant in a patient with mental retardation and ejaculatory dysfunction].

OBJECTIVE: To explore the clinical characteristics and genetic etiology of a patient with mental retardation and ejaculatory dysfunction. METHODS: A patient with mental retardation and ejaculatory dysfunction who was admitted to the First Affiliated Hospital of Air Force Military Medical University on November 18, 2021 was selected as the study subject. Clinical data of the patient were collected. Peripheral venous blood samples were collected from the patient and his parents. Whole exome sequencing (WES) was carried out for the patient, and the candidate variant was verified by Sanger sequencing and bioinformatic analysis. RESULTS: The patient, a 26-year-old male, had manifested atypical mental retardation and ejaculatory dysfunction. WES revealed that he has harbored a heterozygous variant of the ARID1B gene, namely c.5776C>T (p.Arg1926X). Sanger sequencing verified that neither of his parents has carried the same variant. The variant has been recorded in the 1000 Genomes, ExAC, gnomAD and ClinVar databases. A search of the dbSNP database suggested that the variant has a population frequency of 0.000 4%. The variant was predicted as deleterious by online software including Mutation Taster, CADD, and MutPred. Analysis with Cluster Omega online software suggested that the amino acid encoded by the variant site was highly conserved among various species. Analysis with PyMOL software suggested that the variant may affect the function of the encoded protein. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG) and ClinGen, the variant was predicted to be pathogenic. CONCLUSION: The c.5776C>T (p.Arg1926X) variant of the ARID1B gene probably underlay the mental retardation and ejaculatory dysfunction in this patient. Above finding has broadened the spectrum of the ARID1B gene variants and provided reference for the diagnosis and treatment of the patient.

Tetrahedral DNA Nanostructure with Multiple Target-Recognition Domains for Ultrasensitive Electrochemical Detection of Mucin 1.

In this work, a tetrahedral DNA nanostructure (TDN) designed with multiple biomolecular recognition domains (m-TDN) was assembled to construct an ultrasensitive electrochemical biosensor for the quantitative detection of tumor-associated mucin 1 (MUC-1) protein. This new nanostructure not only effectively increased the capture efficiency of target proteins compared to the traditional TDN with a single recognition domain but also enhanced the sensitivity of the constructed electrochemical biosensors. Once the target MUC-1 was captured by the protein aptamers, the ferrocene-marked DNA strands as electrochemical signal probes at the vertices of m-TDN would be released away from the electrode surface, causing significant reduction of the electrochemical signal, thereby enhancing significantly the detection sensitivity. As a result, this well-designed biosensor achieved ultrasensitive detection of the biomolecule at a linear range from 1 fg mL-1 to 1 ng mL-1, with the limit of detection down to 0.31 fg mL-1. This strategy provides a new approach to enhance the detection sensitivity for the diagnosis of diseases.

mTOR pathway gene mutations predict response to immune checkpoint inhibitors in multiple cancers.

BACKGROUND: mTOR pathway is known to promote cancer malignancy and influence cancer immunity but is unknown for its role in immune checkpoint inhibitors (ICI) therapy. METHODS: Using Memorial Sloan-Kettering Cancer Center dataset (MSKCC), we extracted mTOR pathway gene mutations for stepwise Cox regression in 1661 cancer patients received ICI. We associated the mutation of the gene signature resulted from the stepwise Cox regression with the 1661 patients' survival. Other 553 ICI-treated patients were collected from 6 cohorts for validation. We also performed this survival association in patients without ICI treatment from MSKCC as discovery (n = 2244) and The Cancer Genome Atlas (TCGA) as validation (n = 763). Pathway enrichment analysis were performed using transcriptome profiles from TCGA and IMvigor210 trial to investigate the potential mechanism. RESULTS: We identified 8 genes involved in mTOR pathway, including FGFR2, PIK3C3, FGFR4, FGFR1, FGF3, AKT1, mTOR, and RPTOR, resulted from stepwise Cox regression in discovery (n = 1661). In both discovery (n = 1661) and validation (n = 553), the mutation of the 8-gene signature was associated with better survival of the patients treated with ICI, which was independent of tumor mutation burden (TMB) and mainly attributed to the missense mutations. This survival association was not observed in patients without ICI therapy. Intriguingly, the mutation of the 8-gene signature was associated with increased TMB and PD1/PD-L1 expression. Immunologically, pathways involved in anti-tumor immune response were enriched in presence of this mutational signature in mTOR pathway, leading to increased infiltration of immune effector cells (e.g., CD8 + T cells, NK cells, and M1 macrophages), but decreased infiltration of immune inhibitory M2 macrophages. CONCLUSIONS: These results suggested that mTOR pathway gene mutations were predictive of better survival upon ICI treatment in multiple cancers, likely by its association with enhanced anti-tumor immunity. Larger studies are warranted to validate our findings.

Diagnosis and genotype-phenotype correlation in patients with PKD1/TSC2 contiguous gene deletion syndrome.

Deletions involving the TSC2 and PKD1 genes lead to tuberous sclerosis complex (TSC) and autosomal dominant polycystic kidney disease (ADPKD), which is known as TSC2-PKD1 contiguous gene deletion syndrome (PKDTS). PKDTS leads to severe symptoms and death. There are few reported cases of PKDTS, the phenotypic descriptions are poor, and detailed statistics and descriptions of the time of onset and prognosis of PKDTS are lacking. This is the first study to report on the clinical data of PKDTS patients in China. We analyzed all cases including Chinese individuals and summarized the clinical manifestations and genetic characteristics. Our study was the first to use a combination of exome sequencing and multiplex ligation-dependent probe amplification (MLPA) to screen and diagnose PKDTS. We found that many PKDTS patients have the following: multiple renal cysts; angiofibromas (≥ 3) or fibrous cephalic plaque; subependymal nodules; seizures; intellectual disability. PKDTS develops into polycystic kidney disease from before birth to 17 years old and the time of occurrence of end-stage renal disease or dialysis was 21.62 ± 12.87 years of age, which was significantly earlier than in ADPKD caused by PKD1 mutation. Compared with non-Chinese individuals of diverse ancestry, Chinese people have significant differences in the clinical characteristics, including ungual fibromas (≥ 2), and shagreen patch. Five novel large deletions were identified in Chinese. We found no relationship between the clinical phenotype and the genotype. We combined exome sequencing with MLPA to develop a diagnostic method for PKDTS.

DNA Three-Way Junction with Multiple Recognition Regions Mediated an Unconfined DNA Walker for Electrochemical Ultrasensitive Detection of miRNA-182-5p.

In this work, a DNA three-way junction (TWJ) with multiple recognition regions was intelligently engineered, which could be applied as an unconfined DNA walker with a rapid walking speed and high sensitivity for electrochemical detection of microRNA (miRNA-182-5p). Once the target miRNA was presented, the hairpins on TWJ could be successively opened to form an annular DNA walker, which could walk on the entire scope of the electrode surface without the confine for the length of DNA walker legs compared with the traditional DNA walker, greatly improving the walking efficiency. In addition, this DNA walker with multirecognition segments could obviously increase the local concentration of recognition sites, which significantly enhanced the detection speed and sensitivity. As a result, this proposed biosensor with annular DNA as a walker could dexterously achieve the ultrasensitive and fast detection of miRNA-182-5p from 0.1 fM to 1 nM with a detection limit of 31.13 aM. Meaningfully, this strategy explored an innovative path in the design of a new DNA walker nanostructure for accomplishing speedy and sensitive detection of biomarkers.

Programming a "Crab Claw"-like DNA Nanomachine as a Super Signal Amplifier for Ultrasensitive Electrochemical Assay of Hg2.

Herein, with skillfully engaging stable T-Hg2+-T bonding, a "Crab Claw"-like DNA nanomachine with concise and highly efficient assembly and enhanced recognition/conversion efficiency was engineered as a super signal amplifier, which was united with Pd@Cu@Pt multimetallic mesoporous nanomaterials (Pd@Cu@Pt MMNs) for ultrasensitive electrochemical assay of mercury ions (Hg2+). Specifically, the formed "Crab Claw"-like DNA nanomachine could simultaneously trigger four same cascade DNAzyme cleavage reactions with the help of Mg2+ DNAzyme for markedly converting target Hg2+ to enormous DNA segments labeled with ferrocene (Fc), improving the detection sensitivity. Subsequently, the prepared Pd@Cu@Pt MMNs could not only show commendable electrochemical catalysis to Fc but also act as an excellent immobilization matrix for capturing and accumulating abundant Fc around them to further strengthen the electrochemical signal. As a result, the well-designed electrochemical sensor could achieve a low limit of detection of 3.58 fM in the range from 10 fM to 100 nM for Hg2+detection. This strategy offers a simple and rapid avenue to detect heavy metal ions and shows promising application potential for environmental pollutant monitoring.

Engineering a Rolling-Circle Strand Displacement Amplification Mediated Label-Free Ultrasensitive Electrochemical Biosensing Platform.

In this work, an original rolling-circle strand displacement amplification (RC-SDA) was developed by introducing a circle DNA with two recognition domains as a template instead of the limited liner DNA template in traditional strand displacement amplification (SDA), which displayed much shorter reaction time down to 30 min and quite higher conversion efficiency of more than 1.77 × 108 compared with those of traditional strand displacement amplification (SDA) and could be applied to construct a label-free biosensor for ultrasensitive detection of an HIV DNA fragment. Once the target HIV DNA fragment interacts with the template circle DNA, the RC-SDA could be activated to dramatically output amounts of mimic target DNA with the assistance of the Phi29 DNA polymerase and Nb.BbvCI enzyme. In application, while the output products were captured by the DNA tetrahedral nanoprobe (DTNP) modified electrode, the electrochemical tag silver nanoclusters (AgNCs) on DTNP would be released from the electrode surface, accompanied with an obviously decreased electrochemical signal. This way, the developed signal-off biosensor was successfully applied to realize the rapid and ultrasensitive detection of target HIV DNA fragment with a detection limit down to 0.21 fM, which exploits the new generation of a universal strategy beyond the traditional ones for applications in biosensing assay, clinic diagnosis, and DNA nanobiotechnology.

Characterization of PtAOS1 Promoter and Three Novel Interacting Proteins Responding to Drought in Poncirus trifoliata.

Jasmonic acid (JA) plays a crucial role in various biological processes including development, signal transduction and stress response. Allene oxide synthase (AOS) catalyzing (13S)-hydroperoxyoctadecatrienoic acid (13-HPOT) to an unstable allene oxide is involved in the first step of JA biosynthesis. Here, we isolated the PtAOS1 gene and its promoter from trifoliate orange (Poncirus trifoliata). PtAOS1 contains a putative chloroplast targeting sequence in N-terminal and shows relative to pistachio (Pistacia vera) AOS. A number of stress-, light- and hormone-related cis-elements were found in the PtAOS1 promoter which may be responsible for the up-regulation of PtAOS1 under drought and JA treatments. Transient expression in tobacco (Nicotiana benthamiana) demonstrated that the P-532 (-532 to +1) fragment conferring drive activity was a core region in the PtAOS1 promoter. Using yeast one-hybrid, three novel proteins, PtDUF886, PtDUF1685 and PtRAP2.4, binding to P-532 were identified. The dual luciferase assay in tobacco illustrated that all three transcription factors could enhance PtAOS1 promoter activity. Genes PtDUF1685 and PtRAP2.4 shared an expression pattern which was induced significantly by drought stress. These findings should be available evidence for trifoliate orange responding to drought through JA modulation.

Ultrasensitive Electrochemiluminescence Biosensor for Speedy Detection of microRNA Based on a DNA Rolling Machine and Target Recycling.

Intelligent DNA walking machines have become a great hot spot in biosensing, but the walking efficiency of DNA walking machines was still limited due to the low local concentration of substance DNA and the derail of leg DNA. Herein, a Zn2+-driven DNA rolling machine was proposed to overcome the above shortages and applied as a electrochemiluminescence (ECL) biosensor for speedy ultrasensitive detection of microRNA-21. First, the original DNA rolling machine was synthesized by numbers of leg DNA modified on Au nanoparticle which matched with the high concentration of track DNA on the sensing platform and could roll efficiently through Zn2+ driving. By this way the DNA rolling machine not only increased the local concentration of leg DNA and track DNA to improve walking efficiency but also changed the motion mode from step-by-step walking to high-speed rolling, weakening the derailment of leg DNA and shortening the moving time. Second, target-induced recycling and acid dissolution could convert a finite amount of target microRNA into a large amount of Zn2+, which greatly improved the sensitivity of biosensor and overcame the drawbacks of enzyme cleavage or polymerization in common nucleic acid amplification methods. Lastly, the obtained Zn2+ was employed to drive the DNA rolling machine through specific sites recognizing and track DNA cutting to remove a quencher of ferrocene, recovering ECL emission of CdS:Mn QDs for microRNA-21 detection with a detection limit of 0.28 fM. Besides, the biosensor was successfully applied in microRNA-21 analysis from human cancer cell lysates, offered a controllable and ultrasensitive strategy for speedy detection of microRNA, and revealed a new avenue for clinical analyses.

Programming a Target-Initiated Bifunctional DNAzyme Nanodevice for Sensitive Ratiometric Electrochemical Biosensing.

Here, a bifunctional DNAzyme nanodevice (BFDN) with two detection paths toward the same target was intelligently designed and applied to construct a ratiometric electrochemical biosensor for highly reliable and sensitive mercury ion (Hg2+) detection. In the presence of the target Hg2+, the T-Hg2+-T pair could actuate the preassembled DNA four-branched nanostructure (DNA-4B) without cleavage capability transform to the BFDN with strong cleavage capability for triggering two synchronous Hg2+ detection paths, including a "signal-off" path (1) that consisted of a cascade DNAzyme cleavage reaction to dramatically decrease the ferrocene (Fc) response and a "signal-on" path (2) that accomplished the capture of significant amounts of methylene blue (MB) on the electrode surface under the assistant of DNAzyme2 (D2) in BFDN. This strategy not only effectively avoided the false positive signal compared with traditional single paths, but also proposed a new ratiometric method to successfully circumvent the deficiency that existed in previous ratiometric electrochemical biosensors. As a result, the reliable and sensitive Hg2+ detection was achieved in the range from 0.1 pM to 200 nM with a detection limit of 23 fM. Above all, here, the assembly of the BFDN is ingeniously coupled with amplification strategy, paving a promising avenue to promote the performances of simple multifunctional DNA nanomachines and facilitate the corresponding development of DNA nanomachines in biosensor platform.

Simply Constructed and Highly Efficient Classified Cargo-Discharge DNA Robot: A DNA Walking Nanomachine Platform for Ultrasensitive Multiplexed Sensing.

In this work, a classified cargo-discharge DNA robot with only two DNA strands was designed and driven by an analogous proximity ligation assay (aPLA)-based enzyme cleaving for fast walk to construct a novel electrochemical biosensor for simultaneously ultrasensitive detection of microRNA-155 (miRNA-155) and miRNA-21. Compared with traditional DNA nanomachines, the multifunctional DNA robot possessed simple structure, high self-assembling efficiency and walking efficiency. Once it interacted with target miRNAs, this DNA robot could walk fast on the electrode surface and realize the classified cargoes discharging including beacons methylene blue (MB) and ferrocene (Fc), respectively labeled in the double-stranded DNA (A1-A2) for ultrasensitive detection of multiple miRNAs simultaneously. As a result, the wide linearity ranging from 100 aM to 100 pM and low detection limits of 42.7 and 51.1 aM were obtained for miRNA-155 and miRNA-21 detection, respectively. As a proof of concept, the present strategy initiates a novel and highly efficient walking platform to realize the ultrasensitive detection of biomarkers and possesses potential applications in the clinical diagnosis of disease.

Prevalence of workplace violence against healthcare workers: a systematic review and meta-analysis.

We aim to quantitatively synthesise available epidemiological evidence on the prevalence rates of workplace violence (WPV) by patients and visitors against healthcare workers. We systematically searched PubMed, Embase and Web of Science from their inception to October 2018, as well as the reference lists of all included studies. Two authors independently assessed studies for inclusion. Data were double-extracted and discrepancies were resolved by discussion. The overall percentage of healthcare worker encounters resulting in the experience of WPV was estimated using random-effects meta-analysis. The heterogeneity was assessed using the I2 statistic. Differences by study-level characteristics were estimated using subgroup analysis and meta-regression. We included 253 eligible studies (with a total of 331 544 participants). Of these participants, 61.9% (95% CI 56.1% to 67.6%) reported exposure to any form of WPV, 42.5% (95% CI 38.9% to 46.0%) reported exposure to non-physical violence, and 24.4% (95% CI 22.4% to 26.4%) reported experiencing physical violence in the past year. Verbal abuse (57.6%; 95% CI 51.8% to 63.4%) was the most common form of non-physical violence, followed by threats (33.2%; 95% CI 27.5% to 38.9%) and sexual harassment (12.4%; 95% CI 10.6% to 14.2%). The proportion of WPV exposure differed greatly across countries, study location, practice settings, work schedules and occupation. In this systematic review, the prevalence of WPV against healthcare workers is high, especially in Asian and North American countries, psychiatric and emergency department settings, and among nurses and physicians. There is a need for governments, policymakers and health institutions to take actions to address WPV towards healthcare professionals globally.

Prevalence of burnout and associated factors among general practitioners in Hubei, China: a cross-sectional study.

BACKGROUND: High occupational burnout among general practitioners (GPs) is an important challenge to China's efforts to strengthen its primary healthcare delivery; however, data to help understand this issue are unavailable. This study aimed to investigate the prevalence of burnout and associated factors among GPs. METHODS: A cross-sectional design was used to collect data from December 12, 2014, to March 10, 2015, with a self-administered structured questionnaire from 1015 GPs (response rate, 85.6%) in Hubei Province, Central China. Burnout was measured using a 22-item Maslach Burnout Inventory-Human Services Survey (MBI-HSS). MBI-HSS scores and frequency were analyzed by the three dimensions of emotional exhaustion (EE), depersonalization (DP), and personal accomplishment (PA). Factors associated with burnout among GPs were estimated using a multiple linear regression model. RESULTS: Of the respondents, 2.46% had a high level of burnout in all three dimensions, 24.83% reported high levels of EE, 6.21% scored high on DP, and 33.99% were at high risk of PA. GPs who were unmarried, had lower levels of job satisfaction, and had been exposed to workplace violence experienced higher levels of burnout. Intriguingly, no statistically significant associations were found between burnout and the duration of GP practice, age, sex, income, practice setting, and professional level. CONCLUSION: This is the first study of occupational burnout in Chinese general practice. Burnout is prevalent among GPs in Hubei, China. Interventions aimed at increasing job satisfaction, improving doctor-patient relationships and providing safer workplace environments may be promising strategies to reduce burnout among GPs in Hubei, China.

Fluorometric microplate-based dimethoate assay using CdSe/ZnS quantum dots coated with a molecularly imprinted polymer.

A microplate-based assay is described for the sensitive and selective fluorometric determination of the pesticide dimethoate. Molecularly imprinted polymer (MIP)-coated CdSe/ZnS quantum dots (QDs) are used as the molecular recognition probe. The MIP-coated QDs were synthesized using one-step reversed-phase microemulsion in the presence of hydrophobic CdSe/ZnS QDs. Copolymerization was performed by using 3-aminopropyltriethoxysilane as the functional monomer, tetraethoxysilane as the cross-linker, and dimethoate as the template. The fluorescence of the coated QDs is quenched by dimethoate when dimethoate becomes rebound on the imprinting sites of the MIP. Under the optimal conditions, fluorescence (best measured at excitation/emisison wavelengths of 380/620 nm) drops linearly in the 5.0-150 µg L-1 dimethoate concentration range, and the limit of detection is 2.1 µg L-1 (at S/N = 3). The assay was utilized for dimethoate determination in spiked real samples. Satisfactory recoveries (89.8%-98.0%) with relatively standard deviations of <4.9% are obtained. The method is rapid, cost-effective, sensitive, and selective. The use of microplate allows for the quantitation of a large number of samples simultaneously. Graphical abstract Schematic representation of sensitive and selective fluorometric microplate-based assay for the high-throughput determination of dimethoate (DM) based on recognition of molecularly imprinted polymer (MIP)-coated CdSe/ZnS quantum dots (QDs). DM exerts a quenching effect on the fluorescence of the QDs.

Novel 2D-DNA-Nanoprobe-Mediated Enzyme-Free-Target-Recycling Amplification for the Ultrasensitive Electrochemical Detection of MicroRNA.

In this work, on the basis of a new 2D DNA nanoprobe (DNP) and an enzyme-free-target-recycling amplification, an electrochemical biosensor is developed for the ultrasensitive detection of microRNA-21 (miRNA-21). Herein, two ferrocene-labeled bipedal DNPs, which show small steric hindrance and strong stability, are prepared on the basis of the mechanism of the proximity-ligation assay (PLA), improving the space utilization. In the presence of the target, miRNA-21, and a hairpin DNA strand, the DNP will collapse, and then two ferrocene-labeled DNA strands and the miRNA-21 will be simultaneously released from the electrode surface through toehold-mediated strand-displacement reactions (TSDRs), leading to a decrease in the electrochemical signal and realization of enzyme-free target recycling. As a result, the one input target, miRNA-21, could release 2 N ferrocene-labeled DNA strands, achieving a dramatic decrease in the electrochemical signal. Combining DNPs and enzyme-free target recycling, this proposed biosensor showed a linear dependence with miRNA-21 concentration, ranging from 1.0 fM to 10 nM with a detection limit of 0.31 fM. In addition, it is worth mentioning that this biosensor can be regenerated through incubating with three assistant-DNA strands, realizing the reuse of raw materials. Surprisingly, the elaborated biosensor provides a novel strategy for building controllable DNA nanoprobes for the sensitive detection of various biomarkers.

Homogeneous Entropy Catalytic-Driven DNA Hydrogel as Strong Signal Blocker for Highly Sensitive Electrochemical Detection of Platelet-Derived Growth Factor.

In this work, an elegantly designed electrochemical biosensor was constructed for platelet-derived growth factor (PDGF) detection based on homogeneous entropy catalytic-induced DNA hydrogel as a strong signal blocker to significantly inhibit the electrochemical signal of g-C3N4@Au@Fc-NH2 nanomaterials as signal tag. First, the good film-forming nanomaterials of g-C3N4@Au@Fc-NH2, containing large numbers of Fc-NH2 with low resistance and high electric conductivity, were directly immobilized on an electrode surface to provide a strong original electrochemical signal, then the DNA hydrogel blocker formed by target-induced homogeneous entropy catalytic amplification was captured onto the modified electrode surface for significantly reducing the electrochemical signal, in which both the efficient conversion of the single protein to large numbers of DNA strands and the amplification of cycling products could doubly improve the detection sensitivity. As a result, the detection limit could reach 3.5 fM at the range of 0.01 pM to 10 nM. The present strategy by integration of a strong signal blocker to sharply reduce the electrochemical signal of signal tag initiates a new thought to realize the highly sensitive detection of biomarkers and possesses potential applications in clinical diagnosis, sensing, and other related subjects.