Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 488
Filter
Add more filters

Country/Region as subject
Publication year range
1.
Anal Chem ; 96(1): 514-521, 2024 01 09.
Article in English | MEDLINE | ID: mdl-38145394

ABSTRACT

Modulating the photon emission of the luminophore for boosting chemiluminescence (CL) response is very crucial for the construction of highly sensitive sensors via the introduction of functionalized materials. Herein, the integration of the emitter and coreactant accelerator into one entity is realized by simply assembling cucurbit[7]uril (CB[7]) on the surface of gold nanoparticles (AuNPs) through simple assembly via a Au-O bond. The loaded CB[7] on the AuNPs improves their catalytic capacity for the generation of hydroxyl radicals(•OH). Moreover, the host-guest recognition interaction between luminol and CB[7] enables the capture of luminol on AuNPs efficiently. Also, the intramolecular electron-transfer reaction between the luminol and •OH enables the CL response more effectively in the entity, which greatly boosts photon emission ca 100 folds compared with the individual luminol/H2O2. The host-guest recognition between luminol and CB[7] is revealed by Fourier transform infrared spectroscopy, electrochemical, and thermogravimetric characterization. Moreover, the proposed CL system is successfully used for the sensitive and selective determination of dopamine (DA) based on a synergistic quenching mechanism including the competition quenching and radical-scavenging effect from DA. The present amplified strategy by integrating recognized and amplified elements within one entity simplifies the sensing process and holds great potential for sensitive analysis based on the self-enhanced strategies.


Subject(s)
Luminol , Metal Nanoparticles , Luminol/chemistry , Metal Nanoparticles/chemistry , Gold/chemistry , Dopamine , Luminescence , Hydrogen Peroxide/chemistry , Luminescent Measurements/methods
2.
PLoS Comput Biol ; 19(12): e1011738, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38117849

ABSTRACT

Elevated CO2 concentrations have been observed to accelerate flowering time in Arabidopsis through the action of a highly conserved regulatory network controlled by miR156 and miR172. However, the network's robustness to the impact of increasing CO2 concentrations on flowering time remains poorly understood. In this study, we investigate this question by conducting a comprehensive analysis of the global landscape of network dynamics, including quantifying the probabilities associated with juvenile and flowering states and assessing the speed of the transition between them. Our findings reveal that a CO2 concentration range of 400-800ppm only mildly advances flowering time, contrasting with the dramatic changes from 200 to 300ppm. Notably, the feedback regulation of miR156 by squamosal promoter binding protein-like proteins (SPLs) plays a substantial role in mitigating the effects of increasing CO2 on flowering time. Intriguingly, we consistently observe a correlation between delayed flowering time and increased variance in flowering time, and vice versa, suggesting that this might be an intrinsic adaptation mechanism embedded within the network. To gain a deeper understanding of this network's dynamics, we identified the sensitive features within the feedback loops of miR156 SPLs and miR172-APETALA2 family proteins (AP2s), with the latter proving to be the most sensitive. Strikingly, our study underscores the indispensability of all feedback regulations in maintaining both juvenile and adult states as well as the transition time between them. Together, our research provides the first physical basis in plant species, aiding in the elucidation of novel regulatory mechanisms and the robustness of the miRNAs-regulated network in response to increasing CO2, therefore influencing the control of flowering time. Moreover, this study provides a promising strategy for engineering plant flowering time to enhance their adaptation and resilience.


Subject(s)
Arabidopsis Proteins , Arabidopsis , MicroRNAs , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Carbon Dioxide/metabolism , Arabidopsis/metabolism , Transcription Factors/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Gene Expression Regulation, Plant , Flowers/genetics
3.
J Am Chem Soc ; 145(47): 25695-25704, 2023 Nov 29.
Article in English | MEDLINE | ID: mdl-37943722

ABSTRACT

In the energy conversion context, the design and synthesis of high-performance metal-free carbon nanomaterials with topological defects for the oxygen reduction reaction (ORR) are essential. Herein, we first report a template-assisted strategy to fabricate carbon defect electrocatalysts with rich vacancy coupling pentagons (VP) as active sites in two-dimensional (2D) carbon nanosheets (VP/CNs). Experimental characterizations verify the presence of abundant VP active sites in the VP/CNs electrocatalyst, and the ORR activity is linearly related to the amounts of VP active sites. In situ spectroscopic results identify that the VP/CNs can catalyze direct O-O bond cleavage, bypassing the formation of traditional *OOH intermediates, resulting in the fast kinetics of ORR via a dissociative pathway. The as-prepared VP/CNs show outstanding intrinsic activity for alkaline ORR (half-wave potential of 0.86 V vs reversible hydrogen electrode) with an almost 99% efficiency for four-electron selectivity, outperforming that using the benchmark of Pt/C. Density functional theory calculations further reveal that the cooperative effect between carbon vacancy and adjacent pentagons significantly increases the charge transfer and achieves a lower ORR reaction energy barrier compared with the counterpart of adjacent pentagons or single pentagon. The well-designed carbon defects pave a new avenue for the rational design of metal-free electrocatalysts with high efficiency.

4.
Anal Chem ; 95(44): 16234-16242, 2023 11 07.
Article in English | MEDLINE | ID: mdl-37889218

ABSTRACT

As one of the most widely distributed microRNAs, microRNA-21 (miRNA-21) significantly regulates target genes' expression levels and participates in many cellular and intercellular activities, and its abnormal expression is always related to some diseases, especially cancer. Hence, detecting miRNA-21, as a biomarker, at the single-cell level helps us to reveal cell heterogeneity and expression level variation during the state change of cells. In this study, we constructed a gold nanoparticles nanomembrane (AuNPs-NM)-modified plasmonic glass nanopipette (P-nanopipette) surface-enhanced Raman scattering (SERS) sensing platform to sensitively detect content variation of the intracellular miRNA-21 during the electrostimulus (ES)-induced apoptosis process. The cytoplasm-located miRNA-21 was first extracted by using the extraction DNA (HP1)-modified P-nanopipette through a hybridization chain reaction (HCR). The nanopipette was then incubated with a labeling DNA (HP2) and reporter 4-MBA-modified Raman tag. The Raman signal (collected from the tip area near the orifice within 1 µm) showed a good response to the content variation of intracellular miRNA-21 under ES, and the proposed single-cell SERS detection platform provides a simple way to study intracellular substance change and evaluate cancer treatment outcomes.


Subject(s)
Biosensing Techniques , Metal Nanoparticles , MicroRNAs , Gold , DNA , Spectrum Analysis, Raman , Apoptosis
5.
Exp Cell Res ; 420(1): 113339, 2022 11 01.
Article in English | MEDLINE | ID: mdl-36075448

ABSTRACT

Lysine demethylase 1B (Kdm1b) is known as an epigenetic modifier with demethylase activity against H3K4 and H3K9 histones and plays an important role in tumor progression and tumor stem cell enrichment. In this study, we attempted to elucidate the role of Kdm1b in somatic cell reprogramming. We found that exogenous expression of Kdm1b in human dermal fibroblasts (HDFs) can influence the epigenetic modifications of histones. Subsequent analysis further suggests that the overexpression of Kdm1b can promote cell proliferation, reprogram metabolism and inhibit cell apoptosis. In addition, a series of multipotent factors including Sox2 and Nanog, and several epigenetic factors that may reduce epigenetic barriers were upregulated to varying degrees. More importantly, HDFs transfected with the combination of Oct4 (POU5F1), Sox2, Klf4 and c-Myc and Kdm1b (OSKMK) achieved higher reprogramming efficiency. Therefore, we suggest that Kdm1b is an important epigenetic factor associated with pluripotency.


Subject(s)
Cellular Reprogramming , Induced Pluripotent Stem Cells , Oxidoreductases, N-Demethylating , Humans , Cell Differentiation/genetics , Cell Proliferation/genetics , Cellular Reprogramming/genetics , Fibroblasts/metabolism , Gene Expression , Histones/metabolism , Induced Pluripotent Stem Cells/metabolism , Lysine/metabolism , Octamer Transcription Factor-3/genetics , Octamer Transcription Factor-3/metabolism , Oxidoreductases, N-Demethylating/metabolism
6.
Nano Lett ; 22(1): 501-507, 2022 Jan 12.
Article in English | MEDLINE | ID: mdl-34962821

ABSTRACT

A fundamental understanding of the reaction process is essential to predict and enhance the performance of electrochemical devices. As a central reaction in aprotic lithium-oxygen (Li-O2) batteries, the oxygen reduction reaction (ORR) has been confronted with the "sudden-death" phenomenon caused by the cathode passivation from discharge product Li2O2. The soluble catalyst (e.g., reduction mediator) promoted solution-mediated ORR represents an elegant solution. However, no direct molecular evidence is available so far, and its link to Li-O2 batteries performance remains hypothetical. Here, we present in situ surface-enhanced Raman spectroscopy and obtain direct spectroscopic evidence (i.e., LiAQ and LiAQO2) of the solution-mediated ORR on a model anthraquinone (AQ, a typical reduction mediator)-immobilized Au electrode. With the assistance of density functional theory calculations and differential electrochemical mass spectrometry, the related elementary reaction steps of the solution-mediated ORR are proposed. This work provides intuitive insights into the AQ-catalyzed solution-mediated ORR mechanism that is helpful in the optimization and tailor-design of soluble catalysts for excellent next-generation Li-O2 batteries.

7.
J Am Chem Soc ; 144(17): 7741-7749, 2022 05 04.
Article in English | MEDLINE | ID: mdl-35438986

ABSTRACT

Luminol-based electrochemiluminescence (ECL) can be readily excited by various reactive oxygen species (ROS) electrogenerated with an oxygen reduction reaction (ORR). However, the multiple active intermediates involved in the ORR catalyzed with complex nanomaterials lead to recognizing the role of ROS still elusive. Moreover, suffering from the absence of the direct electrochemical oxidation of luminol at the cathode and poor transformation efficiency of O2 to ROS, the weak cathodic ECL emission of luminol is often neglected. Herein, owing to the tunable coordination environment and structure-dependent catalytic feature, single-atom catalysts (SACs) are employed to uncover the relationship between the intrinsic ORR activity and ECL behavior. Interestingly, the traditionally negligible cathodic ECL of luminol is first boosted (ca. 70-fold) owing to the combination of electrochemical ORR catalyzed via SACs and chemical oxidation of luminol. The boosted cathodic ECL emission exhibits electron-transfer pathway-dependent response by adjusting the surrounding environment of the center metal atoms in a controlled way to selectively produce different active intermediates. This work bridges the relationship between ORR performance and ECL behavior, which will guide the development of an amplified sensing platform through rational tailoring of the ORR activity of SACs and potential-resolved ECL assays based on the high-efficiency cathodic ECL reported.


Subject(s)
Biosensing Techniques , Metal Nanoparticles , Catalysis , Electrochemical Techniques , Electrodes , Luminescent Measurements , Luminol , Oxygen , Reactive Oxygen Species
8.
Anal Chem ; 94(2): 1465-1473, 2022 01 18.
Article in English | MEDLINE | ID: mdl-34958552

ABSTRACT

The ever-increasing attention on the highly sensitive biosensors pushes people to explore functional nanomaterials for signal amplification. To endow inert metal-organic frameworks (MOFs) with enzyme mimicking activity, a simple strategy of introducing Cu2+ via coordination with 2,2'-bipyridine ligands of Zr-MOF, just like "Midas touch," is proposed. More details on the coordination environment of Cu active sites in Zr-MOF-Cu are disclosed via electron paramagnetic resonance and synchrotron-radiation-based X-ray absorption fine structure analyses. The as-prepared Zr-MOF-Cu exhibits unparalleled catalytic ability, which can catalyze ascorbic acid (AA) to dehydroascorbic acid and further stimulate the reaction with o-phenylenediamine to produce fluorescent signal probes with 8-fold signal amplification. On the basis of catalyzing the dephosphorylation process of l-ascorbic acid-2-phosphate to yield AA via alkaline phosphatase (ALP) and AA-dependent signal responses, a universal fluorescent system has been successfully constructed for quantitative measurement of the activity of ALP and the ALP-related enzyme-linked immunosorbent assay with carcinoembryonic antigen as a model. Moreover, the stable loading of Cu active sites endows the sensing platform with anti-inference capacity and enables its reuse without loss of catalytic activity after 6 months.


Subject(s)
Biosensing Techniques , Metal-Organic Frameworks , Alkaline Phosphatase/analysis , Catalysis , Humans , Metal-Organic Frameworks/chemistry
9.
Anal Chem ; 94(32): 11360-11367, 2022 Aug 16.
Article in English | MEDLINE | ID: mdl-35921170

ABSTRACT

All-inorganic halide perovskite nanocrystals with their fascinating optical properties have drawn increasing attention as promising nanoemitters. However, due to the intrinsic poor colloidal stability against the external environment, the practical applications are greatly limited. Herein, a facile and effective strategy for the in situ encapsulation of CsPbBr3 NCs into highly dense multichannel polyacrylonitrile (PAN) nanofibers via a uniaxial electrospinning strategy is presented. Such a facile uniaxial electrospinning strategy enables the in situ formation of CsPbBr3 NCs in PAN nanofibers without the introduction of stabilizers. Significantly, the obtained CsPbBr3 nanofibers not only display intense fluorescence with a high quantum yield (≈48%) but also present high stability when exposed to water and air owing to the peripheral protecting matrix of PAN. After immersing CsPbBr3@PAN nanofiber films in water for 100 days, the quantum yield of CsPbBr3@PAN nanofibers maintained 87.5% of the original value, which was much higher than that using CsPbBr3 NCs. Furthermore, based on the spectral overlap between the electrochromic material of ruthenium purple and fluorescence of CsPbBr3@PAN nanofiber films with excellent water stability, a reversible fluorescence switch is constructed with good fatigue resistance, suggesting their promising applications.

10.
Anal Chem ; 94(2): 600-605, 2022 01 18.
Article in English | MEDLINE | ID: mdl-34920663

ABSTRACT

The present detection method for hepatitis B virus (HBV) drug-resistant mutation has a high misdiagnosis rate and usually needs to meet stringent requirements for technology and equipment, leading to complex and time-consuming manipulation and drawback of high costs. Herein, with the purpose of developing cost-effective, highly efficient, and handy diagnosis for HBV drug-resistant mutants, we propose an electrochemical signal-on strategy through the three-way junction (3WJ) transduction and exonuclease III (Exo III)-assisted catalyzed hairpin assembly (CHA). To achieve single-copy gene detection, loop-mediated nucleic acid isothermal amplification (LAMP), one of the highly promising and compatible techniques to revolutionize point-of-care genetic detection, is first adopted for amplification. The rtN236T mutation, an error encoded by codon 236 of the reverse transcriptase region of HBV DNA, was employed as the model gene target. Under the optimized conditions, it allows end-point transduction from HBV drug-resistant mutants-genomic information to electrochemical signals with ultrahigh sensitivity, specificity, and signal-to-noise ratio, showing the lowest detection concentration down to 2 copies/µL. Such a method provides a possibly new principle for ideal in vitro diagnosis, supporting the construction of a clinic HBV diagnosis platform with high accuracy and generalization. Moreover, it is not restricted by specific nucleic acid sequences but can be applied to the detection of various disease genes, laying the foundation for multiple detection.


Subject(s)
Biosensing Techniques , Hepatitis B virus , Biosensing Techniques/methods , Catalysis , DNA/genetics , Exodeoxyribonucleases , Hepatitis B virus/genetics , Nucleic Acid Amplification Techniques/methods
11.
Cell Biol Int ; 46(9): 1409-1422, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35842772

ABSTRACT

Somatic cell reprogramming was achieved by lentivirus mediated overexpression of four transcription factors called OSKM: OCT3/4, SOX2, KLF4, and c-MYC but it was not very efficient. Here, we reported that the transcription factor, LMCD1 (LIM and cysteine rich domains 1) together with OSKM can induce reprogramming of human dermal fibroblasts into induced pluripotent stem cells (iPSCs) more efficiently than OSKM alone. At the same time, the number of iPSCs clones were reduced when we knocked down LMCD1. Further study showed that LMCD1 can enhance the cell proliferation, the glycolytic capability, the epithelial-mesenchymal transition (EMT), and reduce the epigenetic barrier by upregulating epigenetic factors (EZH2, WDR5, BMI1, and KDM2B) in the early stage of reprogramming, making the cells more accessible to gain pluripotency. Additional research suggested that LMCD1 can not only inhibit the developmental gene GATA6, but also promote multiple signaling pathways, such as AKT and glycolysis, which are closely related to reprogramming efficiency. Therefore, we identified the novel function of the transcription factor LMCD1, which reduces the barriers of the reprogramming from somatic to pluripotent cells in several ways in the early stage of reprogramming.


Subject(s)
Cellular Reprogramming , Induced Pluripotent Stem Cells , Cell Proliferation , Co-Repressor Proteins/genetics , Epithelial-Mesenchymal Transition/genetics , Fibroblasts/metabolism , Humans , Induced Pluripotent Stem Cells/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , LIM Domain Proteins/genetics , Transcription Factors/genetics , Transcription Factors/metabolism
12.
J Chem Phys ; 156(22): 225101, 2022 Jun 14.
Article in English | MEDLINE | ID: mdl-35705404

ABSTRACT

We study the stochastic dynamics of the externally regulating gene circuit as an example of an eve-skipped gene stripe in the development of Drosophila. Three gene regulation regimes are considered: an adiabatic phase when the switching rate of the gene from the OFF to ON state is faster than the rate of mRNA degradation; a nonadiabatic phase when the switching rate from the OFF to ON state is slower than that of the mRNA degradation; and a bursting phase when the gene switching is fast and transcription is very fast, while the ON state probability is very low. We found that the rate of thermodynamic cost quantified by the entropy production rate can suppress the fluctuations of the gene circuit. A higher (lower) rate of thermodynamic cost leads to reduced (increased) fluctuations in the number of gene products in the adiabatic (nonadiabatic) regime. We also found that higher thermodynamic cost is often required to sustain the emergence of more gene states and, therefore, more heterogeneity coming from genetic mutations or epigenetics. We also study the stability of the gene state using the mean first passage time from one state to another. We found the monotonic decrease in time, i.e., in the stability of the state, in the transition from the nonadiabatic to adiabatic regimes. Therefore, as the higher rate of thermodynamic cost suppresses the fluctuations, higher stability requires higher thermodynamics cost to maintain.


Subject(s)
Drosophila Proteins , Gene Regulatory Networks , Animals , Drosophila/genetics , Drosophila Proteins/genetics , Epigenesis, Genetic , Gene Expression Regulation , Homeodomain Proteins/genetics , Thermodynamics , Transcription Factors
13.
J Nanobiotechnology ; 20(1): 94, 2022 Feb 23.
Article in English | MEDLINE | ID: mdl-35197099

ABSTRACT

Pancreatic cancer is characterized as the worst for diagnosis lacking symptoms at the early stage, which results in a low overall survival rate. The frequently used techniques for pancreatic cancer diagnosis rely on imaging and biopsy, which have limitations in requiring experienced personnel to operate the expensive instruments and analyze the results. Therefore, there is a high demand to develop alternative tools or methods to detect pancreatic cancer. Herein, we propose a new strategy to enhance the detection sensitivity of pancreatic cancer cells both in biofluids and on tissues by combining the unique property of dopamine coated Fe3O4 nanoparticles (Fe3O4@DOP NPs) to specifically quench and separate free 6-carboxyfluorescein (FAM) labeled DNA (H1-FAM/H2-FAM), and the key feature of hybridization chain reaction (HCR) amplification. We have determined the limit of detection (LOD) to be 21 ~ 41 cells/mL for three different pancreatic cancer cell lines. It was also discovered that the fluorescence intensity of pancreatic cancer cells was significantly higher than that of HPDE-C7 and HepG-2 cells (control cell lines), which express lower MUC1 protein. Moreover, the HCR amplification system was used to identify the cancer cells on pancreatic tissue, which indicated the versatility of our strategy in clinical application. Therefore, the presented detection strategy shows good sensitivity, specificity and has great potential for the diagnosis of pancreatic cancer.


Subject(s)
Biosensing Techniques , Nanocomposites , Pancreatic Neoplasms , Biosensing Techniques/methods , Humans , Indoles , Limit of Detection , Nucleic Acid Hybridization , Pancreatic Neoplasms/diagnosis , Polymers
14.
Anal Chem ; 93(27): 9628-9633, 2021 07 13.
Article in English | MEDLINE | ID: mdl-34213301

ABSTRACT

A chemical fixation strategy originating from single-atom-anchoring with metal-organic frameworks as a carrying matrix was proposed for solid-state electrochemiluminescence (ECL). Herein, UiO-67(N) with the exposure of 2,2'-bipyridine (bpy) ligands could coordinate with Ru2+ to form a local structure of [Ru(bpy)3]2+ (Ru-UiO). The influence of the steric effect induced with different Ru sources was discussed. The as-obtained Ru-UiO exhibits high ECL intensity and outstanding stability in the presence of a coreactant at low concentrations. The proposed synthesis strategy may hold great potential for the synthesis of solid-state ECL materials and their further utilization in ECL analysis.


Subject(s)
Biosensing Techniques , Metal-Organic Frameworks , Electrochemical Techniques , Luminescent Measurements , Photometry
15.
Anal Chem ; 93(17): 6873-6880, 2021 05 04.
Article in English | MEDLINE | ID: mdl-33899464

ABSTRACT

A highly fluorescent emission reaction between terephthalic acid (PTA) and ascorbic acid (AA) via simple control of the reaction temperature was first revealed with the detailed formation mechanism and various characterizations including electron paramagnetic resonance and mass spectrometry. Based on the AA-responsive emission, the alkaline phosphatase (ALP) triggered the transformation of l-ascorbic acid 2-phosphate trisodium salt to AA was integrated with the present system for developing a sensitive, selective, and universal platform. The monitoring of the activity of ALP and the fabrication of ALP-based enzyme-linked immunoassay (ELISA) with carcinoembryonic antigen (CEA) as the model target was performed. The fluorescence intensity correlated well to the CEA concentration in the ranges of 0.25-30 ng/mL, with a detection limit of 0.08 ng/mL. Such a facile protocol based on the fluorescent reaction between PTA and AA without the assistance of catalysis of nanomaterials avoided the laborious synthesis procedure and provided a direct strategy for the early clinical diagnosis coupled with ALP-related catalysis.


Subject(s)
Ascorbic Acid , Carcinoembryonic Antigen/analysis , Enzyme-Linked Immunosorbent Assay , Alkaline Phosphatase , Catalysis , Humans , Nanostructures
16.
Small ; 17(3): e2006553, 2021 01.
Article in English | MEDLINE | ID: mdl-33350148

ABSTRACT

This work reports exquisite engineering of catalytic activity of DNA-templated silver nanoclusters (DNA-AgNCs) based on unique adsorption phenomena of DNAs on DNA-AgNCs and reversible transition between double and triple-stranded DNAs. Four DNA homopolymers exhibit different inhibition effects on the catalytic activity of DNA-AgNCs, poly adenine (polyA) > poly guanine (polyG) > poly cytosine (polyC) > poly thymine (polyT), demonstrating that polyA strands have the strongest adsorption affinity on DNA-AgNCs. Through the formation of T-A•T triplex DNAs, catalytic activity of DNA-AgNCs is restored from the deactivated state by double or single-stranded DNAs, indicating the participation of N7 groups of adenine bases in binding to DNA-AgNCs and blocking active sites. Accordingly, reversibly regulating catalytic activity of DNA-AgNCs can be realized based on DNA input-stimulated transition between duplex and triplex structures. In the end, two low-cost and facile biosensing methods are presented, which are derived from the activity-switchable platform. It is worthy to anticipate that the DNA-AgNCs with controlled catalytic activity will inspire researchers to devise more functionalized nanocatalysts and contribute to the exploration of intelligent biomedicine in the future.


Subject(s)
Biosensing Techniques , Metal Nanoparticles , DNA , DNA Replication , Silver
17.
Small ; 17(26): e2100998, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34075692

ABSTRACT

Transition metal oxides (TMOs) and their heterostructure hybrids have emerged as promising candidates for hydrogen evolution reaction (HER) electrocatalysts based on the recent technological breakthroughs and significant advances. Herein, Ru-Co oxides/Co3 O4 double-shelled hollow polyhedrons (RCO/Co3 O4 -350 DSHPs) with Ru-Co oxides as an outer shell and Co3 O4 as an inner shell by pyrolysis of core-shelled structured RuCo(OH)x @zeolitic-imidazolate-framework-67 derivate at 350 °C are constructed. The unique double-shelled hollow structure provides the large active surface area with rich exposure spaces for the penetration/diffusion of active species and the heterogeneous interface in Ru-Co oxides benefits the electron transfer, simultaneously accelerating the surface electrochemical reactions during HER process. The theory computation further indicates that the existence of heterointerface in RCO/Co3 O4 -350 DSHPs optimize the electronic configuration and further weaken the energy barrier in the HER process, promoting the catalytic activity. As a result, the obtained RCO/Co3 O4 -350 DSHPs exhibit outstanding HER performance with a low overpotential of 21 mV at 10 mA cm-2 , small Tafel slope of 67 mV dec-1 , and robust stability in 1.0 m KOH. This strategy opens new avenues for designing TMOs with the special structure in electrochemical applications.

18.
Nucleic Acids Res ; 47(18): 9502-9510, 2019 10 10.
Article in English | MEDLINE | ID: mdl-31504779

ABSTRACT

Distinct from intermolecular split G-quadruplex (Inter-SG), intramolecular split G-quadruplex (Intra-SG) which could be generated in a DNA spacer-inserted G-quadruplex strand has not been systematically explored. Not only is it essential for the purpose of simplicity of DNA-based bioanalytical applications, but also it will give us hints how to design split G-quadruplex-based system. Herein, comprehensive information is provided about influences of spacer length and split mode on the formation of Intra-SG, how to adjust its thermodynamic stability, and selection of optimal Intra-SG for bioanalysis. For instances, non-classical Intra-SG (e.g. 2:10, 4:8 and 5:7) displays lower stability than classical split strands (3:9, 6:6 and 9:3), which is closely related to integrity of consecutive guanine tract; as compared to regular Intra-SG structures, single-thymine capped ones have reduced melting temperature, providing an effective approach to adjustment of stability. It is believed that the disclosed rules in this study will contribute to the effective application of split G-quadruplex in the field of DNA technology in the future.


Subject(s)
DNA, Intergenic/genetics , DNA/genetics , G-Quadruplexes , Nucleic Acid Conformation , Circular Dichroism/methods , DNA/chemistry , DNA, Intergenic/chemistry , DNA, Intergenic/ultrastructure , Guanine/chemistry , Thermodynamics , Thymine/chemistry
19.
Anal Chem ; 92(24): 16066-16071, 2020 12 15.
Article in English | MEDLINE | ID: mdl-33211481

ABSTRACT

Integrating two kinds of fluorescent probes in one system to develop a ratiometric sensing platform is of prime importance for achieving an accurate assay. Inspired by the efficient overlapped spectrum of 2-aminoterephthalic acid (PTA-NH2) and 2,3-diaminophenazine (DAP), a new sensitive ratiometric fluorescent sensor has been developed for Cu2+ on the basis of in situ converting o-phenylenediamine (OPD) into DAP through the catalysis of Cu2+. Here, the presence of Cu2+ induced the emission of DAP, which acted as an energy acceptor to inhibit the emission of PTA-NH2. This dual-emission reverse change ratiometric profile based on the inner-filter effect improved sensitivity and accuracy, and the highly sensitive determination of Cu2+ with a detection limit of 1.7 nmol·L-1 was obtained. The proposed sensing platform displayed the wide range of detection of Cu2+ from 5 to 200 nmol·L-1 by modulating the reaction time between Cu2+ and OPD. Moreover, based on the specific interaction between glutathione (GSH) and Cu2+, this fluorescent sensor showed high response toward GSH in a range of 0.5-80 µmol·L-1 with a detection limit of 0.16 µmol·L-1. The successful construction of this simple ratiometric sensing platform without the participation of enzymes provides a new route for the detection of small biological molecules that are closely related to human health.

20.
Anal Chem ; 92(7): 5319-5328, 2020 04 07.
Article in English | MEDLINE | ID: mdl-32163269

ABSTRACT

Natural enzyme complex with the subunits cooperating with each other could catalyze cascade reactions in biological system but, just like the limitation of free-floating natural enzymes, usually suffer from deactivation in harsh environment such as high temperature. In this study, a purpose-driven design of amphiphilic aerogel working as the enzymes-immobilization substrate to form the multienzyme complex (MEC) was demonstrated. The aerogel was synthesized only by a single polymer poly(vinyl alcohol) (PVA) as well as a surface modulator maleic acid (MA), the incorporation of which tunes the surface wettability. The usage of the amphiphilic aerogel may do favor for multienzyme immobilization, conserving the enzyme conformation as well as stabilizing the enzymes in high temperature. As a typical example, glucose oxidase and hemin were firmly coimmobilized in the aerogel matrix and actively catalyze the cascade reactions of (i) glucose to gluconic acid and (ii) 3,3,5,5-tetramethylbenzidine (TMB) to its oxidized state. The enzymes could resist the degradation under high temperature (70-100 °C) which is witnessed by the rate of decrease in activity was progressively slackened. Taking the advantage of the chromogenic reaction of TMB, a glucose sensor based on aerogel-enzyme composite for glucose detection in whole blood and sweat was established, exhibiting reliable results and satisfactory recovery. The modified aerogel could also withstand multiple physical deformation meantime maintaining good adsorption capacity as well as catalytic performance. The enzymes-loading aerogel model may hopefully contribute to composing sensors based on other analytes.


Subject(s)
Enzymes, Immobilized/chemistry , Glucose/analysis , Hydrophobic and Hydrophilic Interactions , Limit of Detection , Biocatalysis , Blood Glucose/analysis , Enzyme Stability , Enzymes, Immobilized/metabolism , Gels , Glucose Oxidase/chemistry , Glucose Oxidase/metabolism , Hemin/chemistry , Hemin/metabolism , Humans , Hydrogen-Ion Concentration , Maleates/chemistry , Models, Molecular , Molecular Conformation , Polyvinyl Alcohol/chemistry , Sweat/chemistry , Temperature
SELECTION OF CITATIONS
SEARCH DETAIL