Characterizing nitrogen deposited on urban road surfaces: Implication for stormwater runoff pollution control.

Nitrogen (N) is one of the most important pollutants on urban road surfaces. Understanding the N deposition forms, load characteristics, and influential factors can help to provide management and control strategies for road stormwater runoff pollution. This study focuses on a highly urbanized area in Guangzhou, China, and presents the characteristics of both dissolved and particulate N deposition forms as well as their correlations with land-use types and traffic factors. In addition, an artificial neural network (ANN) based classification model is utilized to estimate N pollution hotspot area and total nitrogen (TN) flux from road to receiving water bodies. The results showed that N on urban road surfaces mainly existed in the form of particulate organic nitrogen. Land use types dominated by residential area (RA) and urban village (UV) have higher TN build-up loads. Geodetector analysis indicated that land use has a greater impact on nitrogen build-up loads than traffic factors. Through classification and estimation using the ANN model, RA, and UV were classified as hotspot areas, and the TN flux from roads in the study area was calculated to be 3.35 × 105 g. Furthermore, it was estimated that the annual TN flux from roads in Guangzhou accounts for 19 % of the city's total urban domestic discharge. These findings are expected to contribute to the pollution control of stormwater runoff from urban road surfaces and provide valuable guidance for enhancing the ecological health of urban water environments.

Clinical efficacy and safety of erlotinib combined with chemotherapy in the treatment of advanced pancreatic cancer: A meta-analysis.

BACKGROUND: Advanced pancreatic cancer is resistant to chemotherapeutic drugs, resulting in limited treatment efficacy and poor prognosis. Combined administration of the chemotherapeutic gemcitabine and erlotinib is considered a potential first-line treatment for advanced pancreatic cancer. However, their comparative benefits and potential risks remain unclear. AIM: To assess the clinical efficacy and safety of erlotinib combined with other chemotherapy regimens for the treatment of advanced pancreatic cancer. METHODS: Literature on the clinical efficacy and safety of erlotinib combined with chemotherapy for advanced pancreatic cancer was retrieved through an online search. The retrieved literature was subjected to a methodological qualitative assessment and was analyzed using the RevMan 5.3 software. Ten randomized controlled trials involving 2444 patients with advanced pancreatic cancer were included in the meta-analysis. RESULTS: Compared with chemotherapeutic treatment, erlotinib combined with chemotherapy significantly prolonged the progression-free survival time of pancreatic cancer patients [hazard ratio (HR) = 0.78, 95%CI: 0.66-0.92, P = 0.003]. Meanwhile, the overall survival (HR= 0.99, 95%CI: 0.72-1.37, and P = 0.95) and disease control rate (OR = 0.93, 95%CI: 0.45-0.91, P = 0.84) were not significantly favorable. In terms of safety, the erlotinib and chemotherapy combination was associated with a significantly higher risk of diarrhea (OR = 3.59, 95%CI: 1.63-7.90, P < 0.05) and rash (OR = 3.63, 95%CI: 1.64-8.01, P < 0.05) compared with single-agent chemotherapy. Moreover, the risk of vomiting (OR = 1.27, 95%CI: 0.62-2.59, P = 0.51), regurgitation/anorexia (OR = 1.61, 95%CI: 0.25-10.31, P = 0.62), and infection (OR = 0.72, 95%CI: 0.28-1.87, P = 0.50) were not significant in either group. CONCLUSION: Compared with a single chemotherapeutic modality, erlotinib combined with gemcitabine can prolong progression-free survival in pancreatic cancer, but does not improve survival benefit or disease control rate, and can increase the risk of diarrhea and rash.

Understanding phosphorus fractions and influential factors on urban road deposited sediments.

Phosphorus (P) is a primary pollutant that builds-up on urban road surfaces. Understanding the fraction and load characteristics of P, as well as their relationship with urban factors, is helpful for assessing the ecological risk of urban receiving water bodies. This study presents the characteristics of build-up loads of P fractions in road-deposited sediments (RDS) in Guangzhou, China, analyzes their correlation with three urban factors (road, traffic, and land-use area), and then estimates the exceedance probability of P in stormwater runoff over the past 10 years. The results showed that detrital apatite phosphorus (De-P) performed the highest build-up load on urban road surfaces, followed by apatite phosphorus (Ca-P), iron-bound phosphorus (Fe-P), exchangeable phosphorus (Ex-P), aluminum-bound phosphorus (Al-P), organophosphorus (POP), dissolved inorganic phosphorus (DIP), occluded phosphorus (Oc-P), and dissolved organic phosphorus (DOP). Depression depth, road materials, and land-use fractions affected the P fractions. The P in the RDS may have originated from three distinct sources: road background, domestic waste, and untreated wastewater discharge. In the most recent 10 years, the event mean concentrations of total P in the RDS have had a 30 % probability of exceeding 0.4 mg L-1, which indicates a serious threat of P to receiving water bodies. The outcomes of this study are expected to provide valuable guidance for elucidating the principal categories of urban non-point source P pollution and enhancing the ecological health of urban water environments.

A study on different types of moral courage and coping styles of clinical nurses: based on potential profile analysis.

BACKGROUND: In professional ethics-related events, there are various unpleasant and complex ethical issues that require strong moral courage. Our aim is to identify and describe the potential categories of moral courage among nurses and to clarify the coping styles of nurses under different categories. METHOD: A cross-sectional study was conducted using three data collection tools: a self-designed general information questionnaire, a Chinese version of the Moral Courage Scale, and a Trait Coping Style Questionnaire. Three hundred fourteen nurses from a tertiary hospital in Heilongjiang Province, China, were analysed using potential profile analysis, descriptive analysis, and Mann-Whitney U test data. RESULT: The latent profile analysis (LPA) results indicate that the two-profile model is the most suitable and supports the existence of two different moral courage profiles: the low moral courage group (60.51%) and the high moral courage group (39.49%), with a high relative entropy value (0.922). The results point to a good profile solution, and there are significant differences between the two profiles. The Mann-Whitney U-test results showed that the positive coping scores of the high moral courage group were significantly higher than those of the low moral courage group, and the negative coping scores of the high moral courage group were significantly lower than those of the low moral courage group. CONCLUSION: Our results reveal the heterogeneity of moral courage in the nurse sample and indicate that nurses in the high moral courage group tend to choose positive coping styles, while nurses in the low moral courage group are more likely to develop negative coping emotions. This provides important significance and reference value for nursing managers, who can propose customised management plans based on the types of moral courage of the nursing community and the coping styles under different categories.

An autonomous driven DNA walker-based electrochemical aptasensor for on-site detection of Ochratoxin A.

Herein, an autonomous driven DNA walker-based aptasensor is proposed for the detection of Ochratoxin A (OTA). A nanoscale metal-organic framework (MOF) is synthesized and used to load Mn2+, a cofactor for DNAzyme. The DNA walker and Mn2+@MOF are assembled on the Au surface, integrating the DNA walker and metal auxiliary ions. The proposed sensor avoids the addition of metal auxiliary ions of DNAzyme from the external environment, which achieves the fully autonomous driving of DNA walker and facilitates the on-site detection of OTA. In addition, the substrate strands are modified with a newly synthesized tetraferrocene signal marker, further achieving signal amplification. The sensor demonstrates a sensitivity of 0.289 pg/mL and is successfully applied to real food sample analysis.

Phase retrieval for objects in rain based on a combination of variational image decomposition and variational mode decomposition in FPP.

As far as we know, there is no paper reported to retrieve the phase of an object in rain by the fringe projection profilometry (FPP) method. The fringe projection pattern taken in rain contains much rain noise, which makes it difficult to accurately retrieve the phase of the object. In this paper, we focus on the phase retrieval of the object in rain by the FPP method. We first decompose the original fringe projection pattern into a series of band-limited intrinsic mode functions by the two-dimensional variational mode decomposition (2D-VMD) method. Then we screen out fringe-associated modes adaptively based on mutual information and reconstruct the fringe projection pattern. Next, we decompose the reconstructed fringe projection pattern by the TGV-Hilbert-BM3D variational model to obtain the de-rained fringe component. Finally, we use the Fourier transform method, phase unwrapping method, and carrier-removal method to obtain the unwrapped phase. We test the proposed method on three fringe projection patterns taken in simulated rain weather, and we compare our proposed method with the phase-shifting method, windowed Fourier method, morphological operation-based bidimensional empirical mode decomposition method, 2D-VMD method, and the TGV-Hilbert-BM3D method. The experimental results demonstrate that, for the first time to our knowledge, our method can effectively retrieve the phase of an object in rain from a single fringe projection pattern.

A self-powered and reagent-less electrochemical aptasensor based on a DNA walker and tetraferrocene for the detection of aflatoxin B1.

We constructed a self-powered and reagent-less electrochemical aptamer sensor for sensitive detection of aflatoxin B1 (AFB1). Here, the metal ion Mn2+ required for the DNAzyme to drive a DNA walker is wrapped in UIO-66(Zr)-(COOH)2 and AFB1 triggers the DNAzyme walking strands to automatically and continuously cut the tetraferrocene-labeled substrate strands, which results in a significant decrease in the electrochemical signal. Under the optimal conditions, the concentration dependence of AFB1 is linear in the concentration range of 0.1 pg mL-1 to 0.195 µg mL-1, and the limit of detection is as low as 4.8 fg mL-1. The sensor displayed good performance even for samples with a complex matrix, such as a peanut sample. The recoveries of AFB1 obtained ranged from 95.5 to 106.8%. The developed sensing platform is reagent-less, self-powered, and highly sensitive. It holds great potential for detection of AFB1 in environmental and food samples.

An electrochemical DNA sensor based on an integrated and automated DNA walker.

As an artificial nanomachine, a DNA walker demonstrates the potential for biosensing. In this study, a highly integrated, biostable, and autonomous electrochemical DNA walker sensor was rationally designed by a simple assembly of a Mn2+-dependent DNAzyme-powered DNA walker with nanoscale Mn2+ @MOFs containing free carboxylic acid groups UiO-66(Zr)-(COOH)2. In this study, the release of Mn2+ from Mn2+@MOFs was exploited to drive the autonomous and progressive operation of the DNA walker, and the DNAzyme-driven DNA walker was constructed by the co-modification of walking strands and track strands onto the gold electrode (GE) surface. The walking strand was a single-stranded DNA containing a DNAzyme sequence, which was pre-silenced by the locking strand. The track strand was a specially designed DNA sequence that the target can hybridize with the locking strand; hence, the walking strand is unlocked, and the liberated DNAzyme catalyzes the cleavage of track strands to drive the DNA walker operation, shifting tetraferrocene away from the electrode and producing a significant signal change. A detection limit of 38 fM was obtained with our new system, exhibiting a wide linear range from 1.5625 × 10-9 M to 1 × 10-13 M. The proposed approach provided a novel means for constructing an highly integrated, automated, and DNAzyme-driven DNA walker for bioanalysis.

Hydrogen sulfide treatment increases the antioxidant capacity of fresh Lingwu Long Jujube (Ziziphus jujuba cv. Mill) fruit during storage.

Hydrogen sulfide (H2S) has been identified as an important gaseous signal molecule in plants. Here, we investigated the effects of H2S on postharvest senescence and antioxidant metabolism of Lingwu Long Jujube (Ziziphus jujuba cv. Mill) fruits (LLJF). Fumigation of Jujube fruits with H2S released from 0.4 mm NaHS could significantly prolong the postharvest shelf life of jujube fruits, reduce the decay rate of fruit, the weight loss of fruit, and inhibit the fruit loss, hardness, color, soluble solids, and titratable acidity. Compared with the control group, exogenous H2S fumigation significantly decreased the loss of chlorophyll, carotenoids, soluble protein, ascorbic acid, phenols, and flavonoids in jujube fruits during post-harvest storage. At the same time, H2S could significantly delay the accumulation of malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide anion (O2 ∙-) and promote catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) activity, and inhibit polyphenol oxidase (PPO) activity. To summarize, H2S can effectively alleviate postharvest senescence and decay of jujube fruits by regulating the ROS accumulation and antioxidant enzymes, and prolong the storage period of postharvest.

Variational image decomposition model TGV-Hilbert-BM3D for phase retrieval in FPP and its application for an on-site wall surface bulge.

Mass loss from wall surface bulge deformation can be used to estimate the strength loss of reinforcement, bond reduction, and ductility degradation, so it is very important to accurately measure the three-dimensional (3D) shape of on-site wall surface bulge. In this paper, we try to solve the problem by use of fringe projection profilometry. In the fringe projection patterns of wall surface bulge, the contrast of the fringes is very weak, and there are sometimes cracks in patterns. We first present a preprocessing method to inpaint fringes if there are damaged fringes caused by cracks. Then we propose a new, to the best of our knowledge, image decomposition model, total generalized variation (TGV)-Hilbert-block-matching (BM)3D, to effectively extract the fringe component. Finally, we use Fourier transform, phase unwrapping, and carrier-removal methods to obtain the unwrapped phase. We test the proposed method on a simulated fringe projection pattern and two real fringe projection patterns of wall surface bulge. We compare our method with the advanced total variation space-generalized functions space-BM3D, TV-Hilbert-L2, and Beppo-Levi-space-Hilbert-BM3D methods. In addition, we perform ablation experiments to prove that our preprocessing method is necessary. The experimental results demonstrate that our method can effectively measure the 3D shape of wall surface bulge from a single fringe projection pattern for the first time, to our knowledge.

Immobilization-free electrochemical DNA sensor based on signal cascade amplification strategy.

The development of convenient and efficient strategies without using complex nanomaterials or enzymes for signal amplification is very important for bioanalytical applications. Herein, a novel electrochemical DNA sensor was developed by harnessing the signal amplification efficiency of catalytic hairpin assembly (CHA) and a brand-new signal marker tetraferrocene. The prepared sensor had both ends of the probe H2 labeled with tetraferrocene; both ends have a large number of unhybridized T bases, which cause tetraferrocene to move closer to the electrode surface, generating a high-efficiency amplification signal. In the presence of target DNA, it induced strand exchange reactions promoting the formation of double-stranded DNA and recycling of target DNA. Under optimal conditions, the sensor showed a good linear correlation between the peak currents and logarithm of target DNA concentrations (ranging from 0.1 fM to 0.3125 pM) with a detection limit of 0.06 fM, which is obtained by a triple signal-to-noise ratio. Additionally, the prepared sensor possesses excellent selectivity, reproducibility, and stability, demonstrating efficient and stable DNA detection methodology.

Integrating Tank Model and adsorption/desorption characteristics of filter media to simulate outflow water quantity and quality of a bioretention basin: A case study of biochar-based bioretention basin.

Reliable approaches for accurately assessing the performance of stormwater treatment systems is essential for their effective design, including filter media selection which can be a significant constituent in stormwater treatment systems. This study presents an innovative modelling approach integrating the Tank Model with the adsorption-desorption characteristics of the filter media. The resulting modelling approach was applied to simulate a field-scale bioretention basin where biochar was used as filter media with over ten years of rainfall records. The resulting outflow and overflow volumes were compared with observed data for calibration. The Stormwater Treatment Tank Model (STTM) was validated using the Leave-One-Out-Cross-Validation (LOOCV) method. The simulation outcomes include water outflow and overflow (quantity) from the bioretention basin as well as outflow water quality represented by three heavy metals (Pb, Cu, and Zn). The modelling approach developed was found to be capable of accurately simulating outflow and overflow volumes, with outlet water quantity being significantly influenced by the total rainfall depth. The modeling results also suggested that a sole treatment system would not be adequate, particularly for large rainfall events (>100 mm) and a treatment train would be more effective. Simulating long-term (over ten years) pollutant removal performance in the bioretention basin indicated that heavy metals outflow event mean concentration (EMCs) values calculated using simulated results of 30% biochar application rate generated the best pollutant removal with consistent values (2.7 µg/L, 3.0 µg/L, 17.2 µg/L for Pb, Cu, and Zn, respectively). These results confirm that the modelling approach is reliable for assessing long-term treatment performance, as well as a robust tool able to contribute to more effective treatment system design, particularly filter media selection and evaluation.

Three-dimensional self-powered DNA walking machine based on catalyzed hairpin assembly energy transfer strategy.

Herein, catalyzed hairpin assembly is implemented as an automated strategy, which can respond in living cells to detect specific target DNA. Using the principle of catalyzed hairpin assembly (CHA), the auxiliary chain connects the fuel and starting chain to form a triple-stranded DNA to complete such a single system. Hundreds of single systems are modified on gold nanoparticles as DNA orbitals. Through the specific recognition of base complementation, the target DNA can realize the automatic walking of the three-dimensional fluorescence machine. This is a novel walking nanomachine that has a simple structure and can independently exist in cells to achieve automatic operation.

Pancreatic cancer with synchronous liver and colon metastases: A case report.

BACKGROUND: Metastasis of pancreatic cancer to the colon is rare and the features need to be further elucidated. Herein, we report a rare case of pancreatic cancer with simultaneous liver and colon metastases. CASE SUMMARY: A 48-year-old man with intrahepatic space-occupying lesions based on a computed tomography scan was admitted to our hospital for further treatment. Abdominal magnetic resonance imaging revealed a 6.4 cm × 4.2 cm mass in the tail of the pancreas and multiple low-density masses in the liver parenchyma. In addition, a mass of 2.2 cm × 1.6 cm with surface congestive erosions in the sigmoid colon was detected by colonoscopy. Histopathological examination of biopsies from both the liver and colon lesions revealed a moderately to poorly differentiated adenocarcinoma. Immunohistochemical staining of the colon tumor was positive for cytokeratin (CK) 7 and CK, but negative for colorectal adenocarcinoma-related markers CK 20, CDX2, and SATB2, thus indicating that the metastasis originated from the pancreas. Next-generation sequencing for genomic profiling of the liver and colon metastases both found mutations in KRAS (p.G12D) and TP53 (c.376-1delG), with microsatellite stable and low tumor mutational burden without actionable or cancer-predisposing gene mutations detected. The patient was subsequently treated with 12 cycles of FOLFIRINOX which led to a sustainable response, followed by ongoing maintenance treatment with irinotecan plus fluorouracil. CONCLUSION: For this rare case, careful evaluation of histopathological and immunohistochemical staining results are required. The genomic profiling of colon lesions was revealed for the first time, and FOLFIRINOX showed good treatment efficacy in this patient.

ULNet for the detection of coronavirus (COVID-19) from chest X-ray images.

Novel coronavirus disease 2019 (COVID-19) is an infectious disease that spreads very rapidly and threatens the health of billions of people worldwide. With the number of cases increasing rapidly, most countries are facing the problem of a shortage of testing kits and resources, and it is necessary to use other diagnostic methods as an alternative to these test kits. In this paper, we propose a convolutional neural network (CNN) model (ULNet) to detect COVID-19 using chest X-ray images. The proposed architecture is constructed by adding a new downsampling side, skip connections and fully connected layers on the basis of U-net. Because the shape of the network is similar to UL, it is named ULNet. This model is trained and tested on a publicly available Kaggle dataset (consisting of a combination of 219 COVID-19, 1314 normal and 1345 viral pneumonia chest X-ray images), including binary classification (COVID-19 vs. Normal) and multiclass classification (COVID-19 vs. Normal vs. Viral Pneumonia). The accuracy of the proposed model in the detection of COVID-19 in the binary-class and multiclass tasks is 99.53% and 95.35%, respectively. Based on these promising results, this method is expected to help doctors diagnose and detect COVID-19. Overall, our ULNet provides a quick method for identifying patients with COVID-19, which is conducive to the control of the COVID-19 pandemic.

A Sensitive Thrombin Aptasensor Based on Target Circulation Strategy.

A convenient homogeneous electrochemical thrombin sensor based on potential-assisted Au-S deposition and a dual signal amplification strategy was established in this study. Potential-assisted Au-S deposition does not require the modification of the gold electrode, thus eliminating the tedious pre-modification of the electrode. To better amplify the output signal, both ends of the signal hairpin probes were modified with a new electroactive substance, tetraferrocene, which was synthesized by the authors. Thrombin was immediately hybridized with a thiol-modified probe to open the stem-loop structure. After chain hybridization, thrombin was replaced and participated in the next round of the reaction; thus, the cascade amplification of the signal was realized. The hybrid chain formed an Au-S deposition under potential assistance, and the electrochemical signal of tetraferrocene could then be measured through differential pulse voltammetry (DPV) and consequently used for the quantitative detection of target thrombin. In addition, the detection limit of thrombin was as low as 0.06 pmol/L, and the detection of common interfering proteins was highly specific.

An electrochemical Hg2+ sensor based on signal amplification strategy of target recycling.

In this work, an unmodified homogeneous electrochemical sensor based on electrochemical bonding and catalytic hairpin assembly (CHA) was first constructed for the high sensitivity detection of Hg2+. Herein, tetraferrocene, a synthesized compound, was used as a signal marker that modified both ends of the hairpin probe to amplify the electrochemical signal. The interaction of T-Hg2+-T could induce the catalytic self-assembly of hairpins by means of auxiliary DNA. The rigid DNA triangle that was formed easily reaches the electrode and induced Au-S self-assembly assisted by potential, allowing tetraferrocene to reach the electrode surface and generate a sensitive electrochemical signal. CHA and tetraferrocene signal markers accomplished dual signal amplification, and the limit of detection was 0.12 pM. Differential pulse voltammetry experiments in the presence of tetraferrocene redox indicator show that the linear response range of electrochemical biosensors to mercury ions is 0.2-2000 pM, This technology offers good selectivity and high recognition efficiency for the detection of mercury ions and has broad application prospects in actual sample detection.

Comparison of pollutant source tracking approaches: Heavy metals deposited on urban road surfaces as a case study.

A range of source tracking approaches have been developed to identify sources in the environmental pollution research field. A comparison of source tracking approaches is essential for a better understanding and practical applications of these approaches. This study compared the commonly used source tracking approaches, namely positive matrix factorization (PMF), Unmix, flag element ratio (FER), and chemical mass-balance based stochastic approach (SCMD). A case study was illustrated for tracing heavy metals (Pb, Zn, Cr, Cu, and Ni) attached to road deposited sediments, which can significantly influence urban road stormwater quality. The results indicated that the accuracy of PMF and Unmix are affected by the number of chemical species used and whether useful markers can be identified for particular sources. However, this does not have an essential influence on FER and SCMD. PMF and Unmix are easier on data preparation and calculation processes but more difficult for source identification process than FER and SCMD. This study also provided recommendations related to the selection of source tracking approach based on different study scenarios and result requirements. These study results are able to provide important guidance for undertaking effective source tracking and devising environmental pollution mitigations.

Toxicity variability of urban road stormwater during storage processes in Shenzhen, China: Identification of primary toxicity contributors and implications for reuse safety.

Urban road stormwater reuse is one of the most important ways to mitigate water resource shortage. Generally, stormwater is stored prior to reuse or further treatment. This study explored the stormwater toxicity variability during two types of storages, closed and open storages using Chinese hamster ovary cells (CHO), which are mammalian cells. The toxicity test by CHO cells can indirectly represent the risk related to human health. Both rainfall (without reaching ground surfaces) and urban road stormwater were collected to undertake laboratory-scaled storage experiments and basic water quality parameters (pH and dissolved oxygen), microorganisms (E.coli and total bacteria), total organic carbon and heavy metals (copper, Cu, zinc, Zn, nickel, Ni, chromium, Cr, cadmium, Cd and lead, Pb) were also investigated during storage processes. The outcomes showed that rainfall has a better water quality with lower toxicity than urban road stormwater (EC50 values of rainfall were generally twice higher than road stormwater). Additionally, it is found that storing road stormwater for a certain period would reduce the toxicity and hence improve their reuse safety (EC50 values in Day 1 were 10.30 mL and 8.46 mL for closed and open storage respectively while they were 14.3 mL and 13.0 mL in Day 7). Organic matters and Cu are important contributors of toxicity during both closed and open storages while bacteria is also essential in toxicity contribution in open storage. The research results implied that storing stormwater for a certain period has a benefit for reuse safety. This is related to cost-effectiveness in terms of treatment system design to avoid over engineering. Additionally, it is suggested that for reducing toxicity, the stormwater treatment designed before/after storage devices should focus on removal of organic matters and heavy metals (specially Cu) as well as restraining bacteria growth.

A homogeneous electrochemical DNA sensor on the basis of a self-assembled thiol layer on a gold support and by using tetraferrocene for signal amplification.

An unmodified electrochemical biosensor has been constructed, which can directly detect DNA in homogeneous solution. The synthesized new compound tetraferrocene was used for signal amplification. The dual-hairpin probe DNA was tagged with a tetraferrocene at the 3' terminal and a thiol at the 5' terminal. Without being hybridized with target DNA, the loop of probe prevented the thiol from contacting the exposed gold electrode surface with an applied potential. After hybridization with the target DNA, the loop-stem structure of the probe was opened, which led to the formation of the hairpin DNA structure. Afterwards, the thiol easily contacted the electrode and accomplished potential-assisted Au-S self-assembly. Its current signal depends on the concentration of target DNA in the 1.8 × 10-13 to 1.8 × 10-9 M concentration range, and the detection limit is 0.14 pM. The technique is a meaningful study because of its high selectivity and sensitivity. Graphical abstract Schematic diagram of the electrochemical DNA sensor operation. Target DNA and probe DNA hybridization, resulting in the disappearance of the steric hindrance of the probe stem ring. A higher signal was generated when tetraferrocene reached the electrode. The electrochemical signals were determined by differential voltammetric pulses (DPV).