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Various isothermal amplification methods have been developed for point-of-care testing (POCT) of various infectious diseases. Here, we proposed a novel isothermal amplification method, named as 5'-half complementary primers mediated isothermal amplification (HCPA). Because of the similarity of our method to the previous method competitive annealing mediated isothermal amplification (CAMP) in primer design, we also use the name CAMP for our method. We demonstrated that CAMP is mediated by both a linear isothermal amplification pattern and a loop-mediated isothermal amplification pattern. To improve the specificity and enable multiplex detection, we further developed HiFi-CAMP method that uses a small amount of high-fidelity DNA polymerase to cut HFman probe to release fluorescent signal. The HiFi-CAMP method was demonstrated to have a good specificity and sensitivity, and fast amplification speed in detection of three human respiratory viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus A (RSV-A) and influenza A viruses (IAV). When compared with gold standard RT-qPCR assays, the HiFi-CAMP assays showed sensitivities of 90.0 %, 71.4 % and 78.1 %, specificities of 100 %, 100 % and 95.5 %, and consistencies of 93.0 %, 93.3 % and 88.2 % for SARS-CoV-2, RSV-A and IAV, respectively. Furthermore, a duplex HiFi-CAMP assay was also developed to simultaneously detect RSV-A and SARS-CoV-2. The HiFi-CAMP will provide a promising candidate for POCT diagnosis in resource-limited settings.
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The electrochemical detection of biosensors is largely governed by the changes in physical properties of redox probes, which are susceptible to electrode substrate effects, inhibiting sensor sensitivity. In this work, a light-driven electrochemical biosensor based on a hybrid nanoantenna was developed for the sensitive detection of fumonisin B1 (FB1). The hybrid nanoantenna sensing interface was constructed by coupling CdSe quantum dots (QDs)-DNA nanowire and graphdiyne oxide composites loaded with methylene blue and gold nanorods (GDYO-MB-Au NRs) using a tetrahedral DNA nanostructure, which acted as a light-driven unit and an amplification unit, respectively. The hybrid nanoantenna with light-driven properties facilitated the alteration in the chemical properties of MB at the sensing interface; that is, MB was degraded under light illumination. The stripping of the CdSe QDs-DNA nanowire triggered by the binding of FB1 could degrade the light-driven capability, thereby improving the electrochemical signal through depressing MB degradation. Taking advantage of the photodegradation of MB by the hybrid nanoantenna, the developed biosensor reduced the background signal and increased the detection sensitivity. The developed biosensor exhibited a linear detection range from 0.5 fg mL-1 to 10 pg mL-1 and a detection limit down to 0.45 fg mL-1. This strategy shows great promise for the fabrication of highly sensitive electrochemical biosensors.
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Técnicas Biossensoriais , DNA , Técnicas Eletroquímicas , Fumonisinas , Pontos Quânticos , Fumonisinas/análise , DNA/química , Pontos Quânticos/química , Luz , Compostos de Cádmio/química , Ouro/química , Compostos de Selênio/química , Nanotubos/química , Limite de Detecção , Nanofios/químicaAssuntos
Dexametasona , Células Matadoras Naturais , Resultado da Gravidez , Útero , Humanos , Feminino , Gravidez , Dexametasona/uso terapêutico , Dexametasona/administração & dosagem , Células Matadoras Naturais/imunologia , Útero/imunologia , Estudos Retrospectivos , Perfusão , Aborto Habitual/imunologia , Aborto Habitual/tratamento farmacológicoRESUMO
Comprehending the charge transfer mechanism at the semiconductor interfaces is crucial for enhancing the electronic and optical performance of sensing devices. Yet, relying solely on single signal acquisition methods at the interface hinders a comprehensive understanding of the charge transfer under optical excitation. Herein, we present an integrated photoelectrochemical surface-enhanced Raman spectroscopy (PEC-SERS) platform based on quantum dots/metal-organic framework (CdTe/Yb-TCPP) nanocomposites for investigating the charge transfer mechanism under photoexcitation in multiple dimensions. This integrated platform allows simultaneous PEC and SERS measurements with a 532 nm laser. The obtained photocurrent and Raman spectra of the CdTe/Yb-TCPP nanocomposites are simultaneously influenced by variable bias voltages, and the correlation between them enables us to predict the charge transfer pathway. Moreover, we integrate gold nanorods (Au NRs) into the PEC-SERS system by using magnetic separation and DNA biometrics to construct a biosensor for patulin detection. This biosensor demonstrates the voltage-driven ON/OFF switching of PEC and SERS signals, a phenomenon attributed to the plasmon resonance effect of Au NRs at different voltages, thereby influencing charge transfer. The detection of patulin in apples verified the applicability of the biosensor. The study offers an efficient approach to understanding semiconductor-metal interfaces and presents a new avenue for designing high-performance biosensors.
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Compostos de Cádmio , Técnicas Eletroquímicas , Ouro , Patulina , Pontos Quânticos , Semicondutores , Análise Espectral Raman , Telúrio , Análise Espectral Raman/métodos , Telúrio/química , Compostos de Cádmio/química , Técnicas Eletroquímicas/métodos , Pontos Quânticos/química , Patulina/análise , Ouro/química , Estruturas Metalorgânicas/química , Técnicas Biossensoriais/métodos , Nanotubos/química , Itérbio/química , Malus/química , Nanocompostos/químicaRESUMO
Apart from mediating viral entry, the function of the free HIV-1 envelope protein (gp120) has yet to be elucidated. Our group previously showed that EP2 derived from one ß-strand in gp120 can form amyloid fibrils that increase HIV-1 infectivity. Importantly, gp120 contains ~30 ß-strands. We examined whether gp120 might serve as a precursor protein for the proteolytic release of amyloidogenic fragments that form amyloid fibrils, thereby promoting viral infection. Peptide array scanning, enzyme degradation assays, and viral infection experiments in vitro confirmed that many ß-stranded peptides derived from gp120 can indeed form amyloid fibrils that increase HIV-1 infectivity. These gp120-derived amyloidogenic peptides, or GAPs, which were confirmed to form amyloid fibrils, were termed gp120-derived enhancers of viral infection (GEVIs). GEVIs specifically capture HIV-1 virions and promote their attachment to target cells, thereby increasing HIV-1 infectivity. Different GAPs can cross-interact to form heterogeneous fibrils that retain the ability to increase HIV-1 infectivity. GEVIs even suppressed the antiviral activity of a panel of antiretroviral agents. Notably, endogenous GAPs and GEVIs were found in the lymphatic fluid, lymph nodes, and cerebrospinal fluid (CSF) of AIDS patients in vivo. Overall, gp120-derived amyloid fibrils might play a crucial role in the process of HIV-1 infectivity and thus represent novel targets for anti-HIV therapeutics.
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Amiloide , Proteína gp120 do Envelope de HIV , Infecções por HIV , HIV-1 , Proteína gp120 do Envelope de HIV/metabolismo , HIV-1/fisiologia , Humanos , Amiloide/metabolismo , Infecções por HIV/virologia , Infecções por HIV/metabolismo , Proteínas Amiloidogênicas/metabolismo , Vírion/metabolismo , Peptídeos/metabolismo , Peptídeos/química , Peptídeos/farmacologiaRESUMO
RESEARCH QUESTION: Do endometrial preparation protocols have an effect on pregnancy outcomes in patients with cured chronic endometritis? DESIGN: A retrospective study was conducted on 3721 infertile patients from December 2018 to August 2020. Endometrial tissues obtained during the proliferative phase were immunostained for CD138. The presence of CD138-positive cells within the stromal cells indicated chronic endometritis. All patients diagnosed with chronic endometritis received oral antibiotics. Patients underwent endometrial preparation and frozen embryo transfer once chronic endometritis was cured. This study compared various endometrial preparation protocols to assess their effects on pregnancy outcomes. Additionally, it aimed to investigate differences in pregnancy outcomes between patients without chronic endometritis and patients with cured chronic endometritis while following the same endometrial preparation protocol. RESULTS: Almost no differences in pregnancy outcomes were observed between natural cycle, hormone replacement therapy (HRT) and gonadotrophin-releasing hormone agonist-HRT (GnRH agonist-HRT) protocols in patients without chronic endometritis and patients with cured chronic endometritis. The only notable difference was that, among women without chronic endometritis, the early miscarriage rate was higher for the GnRH agonist-HRT protocol (25.8%) compared with the natural cycle (17.4%) and HRT (17.7%) protocols (Pâ¯=â¯0.025). However, this difference was not significant after adjusting for confounders (adjusted OR 1.383, 95% CI 0.931-2.055). The live birth rate, clinical pregnancy rate, early miscarriage rate, ectopic pregnancy rate and ongoing pregnancy rate did not differ significantly (P > 0.05) between patients without chronic endometritis and patients with cured chronic endometritis who underwent natural cycle, HRT and GnRH agonist-HRT protocols. CONCLUSION: Endometrial preparation protocols had no impact on pregnancy outcomes in patients with cured chronic endometritis.
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Transferência Embrionária , Endometrite , Endométrio , Resultado da Gravidez , Humanos , Feminino , Gravidez , Endometrite/tratamento farmacológico , Adulto , Estudos Retrospectivos , Endométrio/efeitos dos fármacos , Endométrio/patologia , Doença Crônica , Transferência Embrionária/métodos , Taxa de Gravidez , Infertilidade Feminina/terapia , Infertilidade Feminina/tratamento farmacológico , Terapia de Reposição Hormonal/métodos , Hormônio Liberador de Gonadotropina/agonistasRESUMO
Cutaneous drug reactions (CDRs) are common drug-induced allergic reactions that cause severe consequences in HIV/AIDS patients. The CCL17/CCR4 axis is involved in the immune mechanism of allergic diseases, but its role in the CDRs has not been determined. Here, we aimed to determine the role of the CCL17/CCR4 axis and the underlying mechanism involved in CDRs. In this study, the serum cytokine levels in patients with CDR and healthy controls were measured. The CCL17-triggered allergic profile was screened via a PCR array. Apoptosis of keratinocytes cocultured with CCL17-stimulated Th2 cells was analyzed by flow cytometry. An NVP-induced rat CDR model was established, and dynamic inflammatory factor levels and Th2 cells in the peripheral blood of the rats were measured. Rat skin lesions and signaling pathways in Th2 cells were also analyzed. We showed that the serum CCL17 level was significantly upregulated in CDR patients (P = 0.0077), and the Th2 cell subgroup was also significantly elevated in the CDR rats. The CCL17/CCR4 axis induces Th2 cells to release IL-4 and IL-13 via the ERK/STAT3 pathway. The CCR4 antagonist compound 47 can alleviate rash symptoms resulting from NVP-induced drug eruption, Th2 cell subgroup, IL-4, and IL-13 and inhibit keratinocyte apoptosis. Taken together, these findings indicate that the CCL17/CCR4 axis mediates CDR via the ERK/STAT3 pathway in Th2 cells and type 2 cytokine-induced keratinocyte apoptosis.
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Interleucina-13 , Células Th2 , Humanos , Ratos , Animais , Interleucina-13/metabolismo , Interleucina-4/metabolismo , Citocinas/metabolismo , Transdução de Sinais , Receptores CCR4/metabolismo , Quimiocina CCL17/metabolismo , Fator de Transcrição STAT3/metabolismoRESUMO
Condyloma acuminatum (CA) is a prevalent sexually transmitted disease caused by low-risk human papillomavirus infection, characterized by high transmission and recurrence rates. Long non-coding RNAs (lncRNAs) play a crucial role in regulating gene transcription and are involved in various biological processes. Although recent studies have demonstrated the involvement of lncRNAs in cervical cancer, their expression profile and function in CA remain poorly understood. In this study, we aimed to identify messenger RNA (mRNA) and lncRNA expression patterns in CA using high-throughput lncRNA sequencing. We found that 3033 differentially expressed genes (DEGs) and 1090 differentially expressed lncRNAs (DELs) were significantly altered in CA compared to healthy controls. The results from quantitative reverse transcription polymerase chain reaction and immunohistochemical staining are in accordance with the observed trends in the sequencing data. Functional enrichment analysis revealed that upregulated DEGs in CA were involved in biological processes such as virus response, immune response, cell cycle regulation, the tumor necrosis factor signaling pathway, and the P53 signaling pathway. Co-expression network analysis identified potential target genes of DELs, with enrichment in biological processes such as cell differentiation, the intrinsic apoptotic signaling pathway, and pathways such as virus infection, pathways in cancer, T helper 17 cell differentiation, the mitogen-activated protein kinase signaling pathway, and the Wnt signaling pathway. Collectively, our findings indicate significant changes in the transcriptome profile, including mRNAs and lncRNAs, in CA compared to healthy controls. Our study provides new insights into the potential functions of lncRNAs in the pathogenesis of CA and identifies potential therapeutic targets for this disease.
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Condiloma Acuminado , Perfilação da Expressão Gênica , RNA Longo não Codificante , RNA Mensageiro , Humanos , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , RNA Mensageiro/metabolismo , RNA Mensageiro/genética , Condiloma Acuminado/genética , Condiloma Acuminado/virologia , Feminino , Masculino , Adulto , Redes Reguladoras de Genes , Estudos de Casos e Controles , Pessoa de Meia-IdadeRESUMO
Bis(2-ethylhexyl)phthalate (DEHP), an endocrine disruptor, shows carcinogenic, teratogenic, mutagenic and estrogenic effects. It is easy to release from plastic materials and migrate to soil environment, causing serious pollution and posing a great threat to human health. In our work, a photoelectrochemical (PEC) sensing platform for DEHP detection was constructed using BiOI/ZnO nanoarrays (NRs) as the transducer species and the DEHP aptamers as the biological recognition elements. ZnO NRs with three-dimensional and large diameter area were prepared by hydrothermal method to increase the light absorption capacity. Coupling BiOI in a narrow band gap with ZnO NRs strengthened visible-light absorption, while promoting charge carrier separation and transportation. This was attributed to the generation of an internal electric field between BiOI and ZnO NRs, exhibiting obvious photocurrent response. The as-developed PEC sensing platform demonstrated great sensing performance for detection of DEHP. Furthermore, the photocurrent varied and the logarithm of DEHP concentration showed a linear relationship from 1.0 × 10-11 to 5.0 × 10-7 mol/L, and the limit of detection was estimated to be 3.8 × 10-12 mol/L. In the meantime, while evaluating its usage in real soil samples, satisfying outcomes were realized. Thus, the as-proposed PEC sensing platform provided a potential device to monitor DEHP in the environment.
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Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Dietilexilftalato , Óxido de Zinco , Humanos , Técnicas Biossensoriais/métodos , SoloRESUMO
Leprosy and psoriasis rarely coexist, the specific molecular mechanisms underlying their mutual exclusion have not been extensively investigated. This study aimed to reveal the underlying mechanism responsible for the mutual exclusion between psoriasis and leprosy. We obtained leprosy and psoriasis data from ArrayExpress and GEO database. Differential expression analysis was conducted separately on the leprosy and psoriasis using DEseq2. Differentially expressed genes (DEGs) with opposite expression patterns in psoriasis and leprosy were identified, which could potentially involve in their mutual exclusion. Enrichment analysis was performed on these candidate mutually exclusive genes, and a protein-protein interaction (PPI) network was constructed to identify hub genes. The expression of these hub genes was further validated in an external dataset to obtain the critical mutually exclusive genes. Additionally, immune cell infiltration in psoriasis and leprosy was analyzed using single-sample gene set enrichment analysis (ssGSEA), and the correlation between critical mutually exclusive genes and immune cells was also examined. Finally, the expression pattern of critical mutually exclusive genes was evaluated in a single-cell transcriptome dataset. We identified 1098 DEGs in the leprosy dataset and 3839 DEGs in the psoriasis dataset. 48 candidate mutually exclusive genes were identified by taking the intersection. Enrichment analysis revealed that these genes were involved in cholesterol metabolism pathways. Through PPI network analysis, we identified APOE, CYP27A1, FADS1, and SOAT1 as hub genes. APOE, CYP27A1, and SOAT1 were subsequently validated as critical mutually exclusive genes on both internal and external datasets. Analysis of immune cell infiltration indicated higher abundance of 16 immune cell types in psoriasis and leprosy compared to normal controls. The abundance of 6 immune cell types in psoriasis and leprosy positively correlated with the expression levels of APOE and CYP27A1. Single-cell data analysis demonstrated that critical mutually exclusive genes were predominantly expressed in Schwann cells and fibroblasts. This study identified APOE, CYP27A1, and SOAT1 as critical mutually exclusive genes. Cholesterol metabolism pathway illustrated the possible mechanism of the inverse association of psoriasis and leprosy. The findings of this study provide a basis for identifying mechanisms and therapeutic targets for psoriasis.
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Artrogripose , Hanseníase , Psoríase , Humanos , Hanseníase/genética , Psoríase/genética , Colesterol , Apolipoproteínas E , Biologia ComputacionalRESUMO
The Janus interface, comprising multiple functional heterointerfaces with contrasting functionalities within a single interface, has recently garnered widespread research interest. Herein, a Janus biosensing interface is obtained via wavelength-resolved laser illumination. Deoxyribonucleic acid bridges the electrochemical probe of methylene blue (MB) and plasmonic gold nanoparticles (AuNPs), achieving a sensitive detection performance. MB shows differential electrochemical signals under front (I532front) and back (I650back) laser illumination at 532 and 650 nm, respectively, owing to the selective wavelength-resolved effect. Thus, the presence of a wavelength-resolved laser enabled the design of a biosensing interface with Janus properties. The change in the distance between MB and AuNPs induced by aflatoxin B1 (AFB1) indicates that a sensitive response of the Janus biosensing interface can be achieved. A ratiometric strategy is introduced to describe the electrochemical signals of the I532front and I650back for improved robustness. The obtained linear range is 0.0005-50 ng mL-1, with a detection limit of 0.175 pg mL-1. Our study demonstrated that the wavelength-resolved Janus interface enables an electrochemical biosensor with excellent sensitivity. This finding provides an efficient approach for improving biosensor performance.
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Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanopartículas Metálicas , Ouro/química , Técnicas Eletroquímicas , Nanopartículas Metálicas/química , Luz , Aflatoxina B1/análise , Azul de Metileno/química , Limite de Detecção , Aptâmeros de Nucleotídeos/químicaRESUMO
Here, we develop an all-in-one strategy for efficient assembly of an electrochemical aptasensor. A multifunctional structure based on a tetrahedral DNA nanostructure (TDN) was synthesized via a one-step annealing process, providing DNA fixation, target recognition, signal amplification and space regulation. Based on the integration of this multifunctional structure, the sensing interface was assembled in one step. A ratiometric aptasensor was constructed by anchoring methylene blue (MB) to the TDN and ferrocene (Fc) on the cDNA. Using the ratio of the currents obtained from Fc and MB as a measure, the developed aptasensor shows excellent analytical performance for fumonisin B1 detection. This strategy is universal and could simplify the fabrication of aptasensors.
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Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanoestruturas , Técnicas Eletroquímicas , Aptâmeros de Nucleotídeos/química , Limite de Detecção , Ouro/química , DNA/química , Azul de MetilenoRESUMO
Reversible electrochromic supercapacitors (ESCs) have attracted considerable interest as visual display screens. The use of ESCs in combination with a photoelectrochemical (PEC) biosensor promises to improve the detection efficiency. Herein, a visual PEC biosensor is developed by introducing a circuit module between a PEC-sensing platform (PSP) and a reversible ESC for Cry1Ab protein detection. In PSP, a type II MgTi2O5/CdSe heterojunction effectively drives charge separation by their cross-matched band gap structures, generating an amplified photocurrent. Next, the circuit module is designed to connect the PSP and ESC, realizing the signal conversion from photocurrent to voltage. ESC, as a visual display screen, produces reversible color changes with different voltages. As the concentration of Cry1Ab increases, the photocurrent decreases due to the specific binding between the aptamer and Cry1Ab in PSP, while the color of the reversible ESC changes from green to blue. To improve the integrity of the device, a portable PEC biosensor is further constructed via three-dimensional printing for dual-modal Cry1Ab protein detection, thus collecting both PEC and visual signals. The linear ranges are 0.3-3000 ng mL-1 for PEC mode and 1-1000 ng mL-1 for visual mode. This work presents a portable, efficient, sensitive, and visualized detection system, providing an important reference for practical visualization applications.
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Técnicas Biossensoriais , Compostos de Cádmio , Pontos Quânticos , Compostos de Selênio , Compostos de Cádmio/química , Técnicas Eletroquímicas , Compostos de Selênio/química , Pontos Quânticos/química , Técnicas Biossensoriais/métodos , Limite de DetecçãoRESUMO
OBJECTIVE: To determine the effect of intrauterine perfusion of dexamethasone (DXM) on pregnancy outcomes in recurrent reproductive failure (RRF) patients with elevated uNK cells. METHODS: This retrospective cohort study included 132 RRF patients with elevated uNK cells: 56 patients received DXM treatment and 76 patients refused it in the frozen-thawed embryo transfer cycles. To determine the efficacy of intrauterine perfusion of DXM, multivariate logistic regression models and diagnosis-based subgroup analysis were performed. We also compared the pregnancy outcomes of patients with different responsiveness to DXM treatment. RESULTS: Intrauterine perfusion of DXM significantly improved clinical pregnancy rate (aOR: 3.188, 95% CI: 1.395-7.282, P = .006) and live birth rate (aOR: 3.176, 95% CI: 1.318-7.656, P = .010) in RRF patients with elevated uNK cells, but there was no significant association with miscarriage rate. Subgroup analysis revealed that intrauterine perfusion of DXM in patients with recurrent implantation failure (RIF) showed significant improvement in clinical pregnancy rate (aOR: 6.110, 95% CI: 1.511-24.713, P = .011) and live birth rate (aOR: 9.904, 95% CI: 1.963-49.968, P = .005), but there was insufficient evidence of benefit in recurrent pregnancy loss (RPL) patients. Additionally, uNK cell levels dropped to normal range was achieved in only 35.90% of RRF patients after DXM treatment, no significant difference was found in pregnancy outcomes among patients with different responsiveness to DXM treatment (all P > .05). CONCLUSION: Intrauterine perfusion of DXM was a promising and effective treatment to enhance clinical pregnancy rate and live birth rate in RRF women with abnormally elevated uNK cells, and RIF patients are more likely to benefit than RPL patients.
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Aborto Habitual , Resultado da Gravidez , Gravidez , Humanos , Feminino , Implantação do Embrião , Estudos Retrospectivos , Taxa de Gravidez , Aborto Habitual/tratamento farmacológico , Dexametasona/uso terapêutico , Dexametasona/farmacologia , Perfusão , Células Matadoras NaturaisRESUMO
To evaluate the endometrial immune microenvironment of patients with recurrent miscarriage (RM), a digital immunohistochemistry image analysis platform was developed and validated to quantitatively analyze endometrial immune cells during the mid-luteal phase. All endometrium samples were collected during the mid-luteal phase of the menstrual cycle. Paraffin-embedded endometrial tissues were sectioned into 4 µm thick slides, and immunohistochemistry (IHC)staining was carried out for detecting endometrial immune cells, including CD56+ uNK cells, Foxp3+ Tregs, CD163+ M2 macrophages, CD1a+ DCs, and CD8+ T cells. The panoramic slides were scanned using a digital slide scanner and a commercial image analysis system was used for quantitative analysis. The percentage of endometrial immune cells was calculated by dividing the number of immune cells in the total endometrial cells. Using the commercial image analysis system, quantitative evaluation of endometrial immune cells, which are difficult or impossible to analyze with conventional image analysis, could be easily, and accurately analyzed. This methodology can be applied to quantitatively characterize the endometrium microenvironment, including interaction between immune cells, and its heterogeneity for different reproductive failure patients. The platform for quantitative evaluation of endometrial immune cells may be of important clinical significance for the diagnosis and treatment of RM patients.
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Aborto Habitual , Células Matadoras Naturais , Feminino , Humanos , Imuno-Histoquímica , Endométrio , Linfócitos T CD8-PositivosRESUMO
A recent experimental study showed that inhibitory autapses favor firing synchronization of parvalbumin interneurons in the neocortex during gamma oscillations. In the present paper, to provide a comprehensive and deep understanding to the experimental observation, the influence of inhibitory autapses on synchronization of interneuronal network gamma oscillations is theoretically investigated. Weak, middle, and strong synchronizations of a globally inhibitory coupled network composed of Wang-Buzsáki model without autapses appear at the bottom-left, middle, and top-right of the parameter plane with the conductance (gsyn) and the decay constant (τsyn) of inhibitory synapses taken as the x-axis and y-axis, respectively. After introducing inhibitory autapses, the border between the strong and middle synchronizations in the (gsyn, τsyn) plane moves to the top-right with increasing the conductance (gaut) and the decay constant (τaut) of autapses, due to that interspike interval of the single neuron becomes longer, leading to that larger τsyn is needed to ensure the strong synchronization. Then, the synchronization degree of middle and strong synchronizations around the border in the (gsyn, τsyn) plane decreases, while of strong synchronization in the remaining region remains unchanged. The synchronization degree of weak synchronization increases with increasing τaut and gaut, due to that the inhibitory autaptic current becomes strong and long to facilitate synchronization. The enhancement of weak synchronization modulated by inhibitory autapses is also simulated in the random, small-world, and scale-free networks, which may provide explanations to the experimental observation. These results present complex dynamics of synchronization modulated by inhibitory autapses, which needs future experimental demonstrations.
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The electronic contact between two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors and metal electrodes is a formidable challenge due to the undesired Schottky barrier, which severely limits the electrical performance of TMD devices and impedes the exploration of their unconventional physical properties and potential electronic applications. In this study, we report a two-step chemical vapor deposition (CVD) growth of 2D TaSe2-WSe2 metal-semiconductor heterostructures. Raman mapping confirms the precise spatial modulation of the as-grown 2D TaSe2-WSe2 heterostructures. Transmission electron microscopy (TEM) characterization reveals that this two-step method provides a high-quality and clean interface of the 2D TaSe2-WSe2 heterostructures. Meanwhile, the upper 1T-TaSe2 is formed heteroepitaxially on/around the pre-synthesized 2H-WSe2 monolayers, exhibiting an epitaxial relationship of (20-20)TaSe2//(20-20)WSe2 and [0001]TaSe2//[0001]WSe2. Furthermore, characterization studies using a Kelvin probe force microscope (KPFM) and electrical transport measurements present compelling evidence that the 2D metal-semiconductor heterostructures under investigation can improve the performance of electrical devices. These results bear substantial significance in augmenting the properties of field-effect transistors (FETs), leading to notable improvements in FET mobility and on/off ratio. Our study not only broadens the horizons of direct growth of high-quality 2D metal-semiconductor heterostructures but also sheds light on potential applications in future high-performance integrated circuits.
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Aflatoxin B1 (AFB1) contamination has received considerable attention for the serious harm it causes and its wide distribution. Hence, its efficient monitoring is of great importance. Herein, a space-confined electrochemical aptasensor for AFB1 detection is developed using a conductive hydrogel. Plasmonic gold nanoparticles (AuNPs) and methylene blue-embedded double-stranded DNA (MB-dsDNA) were integrated into the conductive Au-hydrogel by ultraviolet (UV) polymerization. Specific recognition of AFB1 by the aptamer released MB from MB-dsDNA in the matrix. The free DNA migrated to the outer layer due to electrostatic repulsion during the Au-hydrogel formation. The electrochemical aptasensor based on this Au-hydrogel offered a twofold enlarged oxidation current of MB (IMB) compared with that recorded in the homogeneous solution for AFB1 detection. Upon light illumination, this IMB was further enlarged by the local surface plasmon resonance (LSPR) of the AuNPs. Ultimately, the Au-hydrogel-based electrochemical aptasensor provided a detection limit of 0.0008 ng mL-1 and a linear range of 0.001-1000 ng mL-1 under illumination for AFB1 detection. The Au-hydrogel allowed for space-confined aptasensing, favorable conductivity, and LSPR enhancement for better sensitivity. It significantly enhanced the applicability of the electrochemical aptasensor by avoiding complicated electrode fabrication and signal loss in a bulk homogeneous solution.
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Aptamers with strong affinity to heavy metal ions (HMIs) allow fabrication of electrochemical sensors with high selectivity and sensitivity, while controllable regulation of aptamer-HMI recognition at the sensing interface, which is vital for better analytical performance, remains challenging. Here, an electric field-based strategy for engineering an aptasensing interface was proposed to realize the specific preconcentration and accurate detection of mercury (Hg2+) and lead (Pb2+) ions with a ratiometric electrochemical sensor. The working principle is to apply an electric field to drive HMIs to approach the aptamer and retain the orientation of the DNA structure. Anthraquinone-2-carboxylic acid (AQ)-labeled complementary DNA was designed to simultaneously bind a ferrocene (Fc)-labeled aptamer for Hg2+ and a methylene blue (MB)-labeled aptamer for Pb2+, and the sensing interface was fabricated with this presynthesized DNA structure. For preconcentration, an electric field of 3.0 V pushed HMIs to approach the aptamer and retained the orientation of DNA to favor the following recognition; for detection, the oriented DNA in 2.5 V electric field offered a stable current of AQ as a reference. In this way, currents of AQ, Fc and MB were used to produce ratiometric signals of IAQ/IFc and IAQ/IMB for Hg2+ and Pb2+, respectively. Such a strategy allowed the simultaneous detection of Hg2+ and Pb2+ within 30 min with detection limits of 0.69 pM and 0.093 pM, respectively. The aptasensor was applied for soil, water, and crayfish analysis in paddy fields. The electric field-enabled strategy offers a new way to fabricate high-performance electrochemical aptasensor for HMIs detection.
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Mercúrio , Animais , Chumbo , Astacoidea , Íons , Azul de MetilenoRESUMO
The development of accurate and reliable sensor for on-site detection of microcystin-LR (MC-LR), one of hazardous environmental pollutants, is highly required. Herein, a laser induced graphene (LIG)-based electrochemical aptasensor for sensitive on-site detection of MC-LR was reported. LIG electrode, the substrate of aptasensor, was prepared via thermal transfer with ethylene-vinyl acetate copolymer, and LIG acted as quasi-reference electrode to replace conventional Ag/AgCl electrode for better operability and robustness. LIG electrode provided large surface area to assemble tetrahedral DNA to absorb methylene blue (MB) for the signal amplification. For detection, the specific recognition of MC-LR with aptamer led to the stripping of tetrahedral DNA complex and further the decreased redox current of MB (IMB). Consequently, the fabricated aptasensor offered high analytical performance for MC-LR detection with a linear range of 1 × 10-2-1 × 105 pM and a detection limit of 3 × 10-3 pM, which was successfully used for water sample analysis with comparable reliability and accuracy of standard method. Furthermore, a portable detection platform by coupling of LIG-based electrochemical aptasensor with electrochemical workstation was constructed for on-site detection of MC-LR. This work offers a novel method for the on-site monitoring of MC-LR, which promotes the investigation of LIG-based electrochemical biosensing in the field of environmental analysis.