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Programming ultrasensitive and stimuli-responsive DNAzyme-based probes holds great potential for on-demand biomarker detection. Here, an optically triggered DNAzyme platform was reported for on-demand activation-sensitive electrochemiluminescence (ECL) c-myc mRNA analysis. In this design, the sensing and recognition function of the split DNAzyme (SDz) probe was silent by engineering a blocking sequence containing a photocleavable linker (PC-linker) group at a defined site that could be indirectly cleaved by 302 nm ultraviolet (UV) light. When the SDz probes were assembled on the Au nanoparticles and potassium (K) element doped graphitic carbon nitride nanosheet (K-doped g-C3N4) covered electrode, UV light activation induces the configurational switching and consequently the formation of an active DNAzyme probe with the help of target c-myc mRNA, allowing the cleavage of the substrate strand by magnesium ions (Mg2+). Thus, the release of a ferrocene (Fc)-labeled DNAzyme 2 strand contributed to an extreme ECL signal recovery. In the meantime, the released target c-myc mRNA combined another inactive SDz motif to form active DNAzyme and repeat the cyclic cleavage reaction, resulting in the signal amplification. Furthermore, according to the responses toward two other designed nPC-SDz and m-SDz probes, we demonstrated that controlled UV light mediated photoactivation of the DNAzyme biosensor "on demand" effectively constrained the ECL signal to the mRNA of interest. Moreover, false positive signals could also be avoided due to such a photoactivation design with UV light. Therefore, this study provided a simple methodology that may be broadly applicable for investigating the mRNA-associated physiological events that were difficult to access using traditional DNAzyme probes.
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ADN Catalítico , Técnicas Electroquímicas , Mediciones Luminiscentes , ARN Mensajero , ADN Catalítico/metabolismo , ADN Catalítico/química , Técnicas Electroquímicas/métodos , ARN Mensajero/análisis , Humanos , Rayos Ultravioleta , Técnicas Biosensibles/métodos , Oro/química , Nanopartículas del Metal/química , Nanopartículas del Metal/efectos de la radiación , Procesos Fotoquímicos , Proteínas Proto-Oncogénicas c-myc/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , Grafito/química , Límite de Detección , Compuestos de NitrógenoRESUMEN
The release of radioactive iodine into the environment poses a significant threat, as it can contaminate soil, water, and food chains, leading to detrimental effects on ecosystems and biodiversity. Hence, employing the adsorption method proves to be a simple yet effective approach for treating radioactive waste. N/O-codoped ultrathin porous biochar, synthesized from casein using NaHCO3 activation, emerges as a potential candidate for adsorption materials. The saturation level of I2 adsorption in 100 mg L-1 iodine-cyclohexane solution is 73 mg·g-1 at 20 min. The density functional theory (DFT) calculations and experiments attribute this phenomenon to the presence of graphite nitrogen (NG) and C-OH groups on the biochar surface. Furthermore, the pseudo-first-order model fits better with the experimental values, suggesting that the adsorption of iodine by the adsorbent is primarily physisorption-based. The Freundlich isotherm is suitable for iodine adsorption of biochar, owing to the abundance of adsorption sites within the porous structure, particularly at the edges, which enhance the adsorption activity. Significantly, the study highlights that NG adsorptive sites exhibit 1.5 times higher adsorption activity compared to C-OH adsorptive sites, underscoring the essential role of NG in iodine adsorption for electron transfer. Overall, these findings underscore the potential of N/O-codoped ultrathin porous biochar in effectively mitigating the presence of radioactive I2, showcasing its promise in addressing environmental challenges associated with radioactive contamination.
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Herein, an electrochemiluminescence (ECL) and electrochemical (EC) dual-mode biosensor platform with a self-powered DNAzyme walking machine was established for accurate and sensitive detection of miRNA-21. By employing a magnesium ion (Mn2+)-dependent DNAzyme cleavage cycling reaction, the walking machine was built by assembling DNAzyme walking strands and ferrocene (Fc)-labeled substrate strands on the Au nanoparticles and graphitic carbon nitride nanosheet (g-C3N4 NS)-covered electrode. The DNAzyme walking strand was first prohibited by a blocker strand. After the addition of target miRNA-21 and Mn2+, the DNAzyme walker could be activated and produce autonomous movements along the electrode track fueled by Mn2+-dependent DNAzyme-catalyzed substrate cleavage without additional energy supply. Notably, each walking step resulted in the cleavage of a substrate strand and the release of a Fc-labeled DNA strand fragment, allowing us to acquire an extreme ECL signal recovery of g-C3N4 inhibited by Fc. Meanwhile, numerous Fc-labeled DNA fragments escaped from the surface of the electrode, directly producing an obvious decrease in the square wave voltammetry (SWV) signal from Fc on the same sensing platform. This work not only avoided difficultly assembling various signal indicators but also significantly improved the sensitivity through using self-powered DNAzyme-walker amplification. Moreover, the proposed design employed the same reaction to produce two signal output modes, which could eliminate the interference from diverse reactive pathways on the outcome to mutually improve the accuracy. Therefore, the dual-mode miRNA-21 biosensor exhibited wide detection ranges of 100 aM to 100 nM with low detection limits of 54.3 and 78.6 aM by ECL and SWV modes, respectively, which provided an efficient and universal biosensing approach with extensive applications in early disease diagnosis and bioanalysis.
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Técnicas Biosensibles , ADN Catalítico , Nanopartículas del Metal , MicroARNs , Técnicas Biosensibles/métodos , ADN/metabolismo , ADN Catalítico/metabolismo , Técnicas Electroquímicas/métodos , Oro , Límite de Detección , MicroARNs/análisis , Mediciones LuminiscentesRESUMEN
Förster resonance energy transfer (FRET) from fluorescent nanoparticles to fluorescent dyes is an attractive approach for bioanalysis in living cells. However, the luminescence of the nanoparticle donor/acceptor has not been effectively used to produce highly efficient FRET because the distance between the energy donor and energy acceptor is often larger than the effective FRET radius (about 10 nm) and the uncontrolled rotational and translational diffusion of luminophores. Here, we develop an aggregation-enhanced energy transfer strategy that can overcome the impedance for effective energy transfer. The functional nanoprobes, named TPP-CDs-FITC, are carbon dots (CDs) functionalized with triphenylphosphine (TPP) and â¼117 fluorescein 5-isothiocyanate (FITC) on the surface. In dispersed solution, the 3.8 nm TPP-CDs-FITC show weak FRET efficiency (15.4%). After TPP-instructed mitochondrial targeting, enhanced FRET efficiency (53.2%) is induced due to the aggregation of TPP-CDs-FITC selectively triggered by adenosine triphosphate (ATP) in the mitochondria. The enhanced FRET efficiency can be attributed to the joint effect of the augment of numbers of FITC acceptors within 10 nm from dispersed 117 to aggregated 5499 and the restricted rotational and translational motions of TPP-CDs donors and FITC acceptors. Ultimately, we successfully observe the fluctuations of ATP levels in the mitochondria using the aggregation-enhanced energy transfer strategy of the TPP-CDs-FITC nanodevice.
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Adenosina Trifosfato , Transferencia Resonante de Energía de Fluorescencia , Fluoresceína-5-Isotiocianato , Colorantes Fluorescentes , MitocondriasRESUMEN
Polycationic Pp-x@g-C3N4 composite was synthesized through an in situ polymerization process of N-alkylpyridinium acetylenic alcohol bromide (p-x) above the surface of g-C3N4. The structure of p-0 and the Pp-x@g-C3N4 properties were checked by modern technologies. Photocatalytic tests of Pp-x@g-C3N4 in water splitting unveiled much better Pp-x@g-C3N4 hydrogen evolution activities by comparison with both g-C3N4 and Pp-0. The hydrogen production by Pp-0@g-C3N4 was 1654.5 µmol h-1 g-1, which is â¼26- and 22-fold greater in relation to what g-C3N4 and Pp-0 produced (62.7 and 75.0 µmol h-1 g-1, respectively), suggesting strong bilateral and synergistic interactions of g-C3N4 with Pp-0. Although the lengthening methylene chain in the polymers weakened the hydrogen generation ability of Pp-x@g-C3N4, the conjugated double bonds, solubilization, and dispersion of Pp-x polycationic surfactants made Pp-x@g-C3N4 superior to g-C3N4 in water splitting. Due to the readily available raw materials, a simple way of preparation (starting chemicals to p-0 to Pp-0@g-C3N4), high photocatalysis efficiency, light irritation stability, recyclable ability, and low toxicity, Pp-0@g-C3N4 is a good candidate for water splitting.
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The sheet-like adsorbent of the eggshell wastes was prepared by the thermal hydrolysis method. The structure of the adsorbent was characterized by scanning electron microscope, Brunauer-Emmett-Teller, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectrometer. The adsorption capacity was investigated in a Pb2+ solution. The effects of initial pH, salt concentration, contact time, and adsorbate concentration on the adsorption of lead ions were investigated in detail. The morphology of the adsorbent was sheet-like microspheres. Zinc selenide/zinc oxide could be uniformly loaded onto the eggshell waste surface, which could effectively enhance the specific surface area of the eggshell wastes. The adsorption kinetics and isotherm followed the pseudo-second-order and Langmuir-Freundlich isotherm model, respectively. The synthesized adsorbent showed a maximum lead adsorption capacity of 1,428.78 mg/g at room temperature. Ion-exchange was the main adsorption mechanism.
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Contaminantes Químicos del Agua , Óxido de Zinc , Adsorción , Animales , Concentración de Iones de Hidrógeno , Iones , Cinética , Plomo , SolucionesRESUMEN
A novel adsorbent consisting of polyethyleneimine-modified multi-wall carbon nanotubes (PEI-MWCNTs) was synthesized by grafting PEI on the carboxyl MWCNTs. The surface properties of the PEI-MWCNTs were measured by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, and zeta potential. The adsorption behavior of the PEI-MWCNTs was investigated using sunset yellow FCF as adsorbate. The effects of dosage of adsorbent, the initial pH of solution, contact time and temperature on the adsorption capacity were studied. Then, the kinetics and thermodynamics of the adsorption process were further investigated. Experimental results showed that the adsorption kinetics fitted a pseudo-second-order model and the adsorption isotherms agreed well with the Langmuir model. The adsorption process occurred very fast and the adsorption capacity of PEI-MWCNTs was much higher than that of many of the previously reported adsorbents. Additionally, the plausible adsorption mechanism was discussed.
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Compuestos Azo/química , Nanotubos de Carbono/química , Polietileneimina/química , Contaminantes Químicos del Agua/química , Adsorción , Cinética , Microscopía Electrónica de Rastreo , Estructura Molecular , Soluciones , Propiedades de Superficie , Temperatura , Termodinámica , Purificación del Agua/métodosRESUMEN
Lead-free piezoceramics of Bi0.5(Na0.825K0.175)0.5TiO3 with varying concentrations of x mol% Ag2O (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, denoted as BNKT-xA) were fabricated using the solid-state technique. An extensive investigation was undertaken to analyze the structural, piezoelectric, and dielectric properties of these piezoceramics in the presence of Ag ions. There is no evidence of any secondary solid solution in the BNKT-xA piezoceramics. The ceramics with x mol% Ag2O in BNKT still demonstrate the presence of both rhombohedral (R) and tetragonal (T) phases. The addition of Ag+ is helpful to increase the relative density of the BNKT-xA piezoceramics. It is noteworthy that the BNKT-0.3 mol% A piezoceramics show remarkable improvements in their properties (d33 = 147 pC/N, kp = 29.6%, ε = 1199, tanδ = 0.063). These improvements may be ascribed to the denser microstructure and the preservation of morphotropic phase boundaries between R and T phases caused by the appropriate addition of Ag cations. The addition of Ag+ results in the relaxor behavior of the BNKT-xA ceramics, characterized by disorder among A-site cations. With the increase in temperature, the d33 value of BNKT-xA ceramics does not vary significantly in the range of 25 to 125 °C, ranging from 127 to 147 pC/N (with a change of d33 ≤ 13.6%). This finding shows that piezoelectric ceramics have a reliable performance over a certain operating temperature range.
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Prussian blue (PB) is widely used for the selective removal of radioactive cesium ions (Cs+) from aqueous solutions. Due to its small size and easy dispersion in water, PB requires a carrier that is both inexpensive and easily separable. Magnetic porous biochar (MPBC) was formed by activating starch with FeCl3 through a one-step calcination method. MPBC can be used as a carrier for Prussian blue, which is easily separated from the solution. This composite material (PB/MPBC) has a rich pore structure and maintains effective surface area, which can facilitate the penetration of Cs+ into the adsorbent. Besides, PB/MPBC exhibits high selectivity and good adsorption capacity achieving a large removal capacity of 101.43 mg/g. Thus, this study provides a novel approach for preparing composites with efficient removal of Cs+.
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Cesio , Contaminantes Químicos del Agua , Cesio/química , Porosidad , Adsorción , Agua , Iones , Contaminantes Químicos del Agua/química , Fenómenos Magnéticos , CinéticaRESUMEN
The catalytic conversion of nitrogen to ammonia is one of the most significant processes in nature and the chemical industry. However, the traditional Haber-Bosch process of ammonia synthesis consumes substantial energy and emits a large amount of carbon dioxide. The efficiency of photocatalytic N2 activation is severely limited by the lack of N2 adsorption sites and poor carrier utilization. Herein, an efficient α-Bi2O3/Bi3O4Br heterojunction is proposed with a photocatalytic nitrogen fixation activity of 238.67 µmol·g-1·h-1. Compared with the BiOBr precursor, α-Bi2O3 and Bi3O4Br, the α-Bi2O3/Bi3O4Br heterojunction with oxygen vacancies can improve the adsorption and activation capacity of N2 and promote the separation efficiency of charge carrier pairs by accommodating photogenerated electrons under visible light through the mechanism of N-type semiconductors. Therefore, oxygen vacancies and heterojunction engineering of semiconductive nanomaterials provide a promising method for the rational design of photocatalysts to enhance the rate of ammonia synthesis under mild conditions.
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Excessive tetracycline in the water environment may lead to the harming of human and ecosystem health. Removing tetracycline antibiotics from aqueous solution is currently a most urgent issue. Porous graphitic biochar with an ultra-large surface area was successfully prepared by a one-step method. The effects of activation temperature, activation time, and activator dosage on the structural changes of biochar were investigated by scanning electron microscopy, Brunauer-Emmett-Teller, X-ray powder diffraction, and Raman spectroscopy. The effect of the structure change, adsorption time, temperature, initial pH, and co-existing ions on the tetracycline removal efficiency was also investigated. The results show that temperature had the most potent effect on the specific surface area, pore structure, and extent of graphitization. The ultra-large surface area and pore structure of biochar are critical to the removal of tetracycline. The q e of porous graphitic biochar could reach 1122.2 mg g-1 at room temperature. The calculations of density functional theory indicate that π-π stacking interaction and p-π stacking interaction can enhance the tetracycline adsorption on the ultra-large surface area of graphitic biochar.
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Electroreduction of nitrite (NO2 - ) to ammonia (NH3 ) provides a sustainable approach to yield NH3 , whilst eliminating NO2 - contaminants. In this study, Ni nanoparticles strutted 3D honeycomb-like porous carbon framework (Ni@HPCF) is fabricated as a high-efficiency electrocatalyst for selective reduction of NO2 - to NH3 . In 0.1â M NaOH with NO2 - , such Ni@HPCF electrode obtains a significant NH3 yield of 12.04â mg h-1 mgcat. -1 and a Faradaic efficiency of 95.1 %. Furthermore, it exhibits good long-term electrolysis stability.
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By controlling the species of the organic sulfur source, CdS samples were produced with different photocatalytic performances by a low-temperature solvothermal method. Different species of the organic sulfur source were chosen as the coordination agent to control the interactions in the crystal growth process. Among them, thioacetamide was the best coordination agent. The hydrophobic chain could be good for reducing the resistance of charge transfer, and increasing the rate of surface charge transfer and the lifetime of the photoexcited electrons. Benefiting from the hydrophobic chain, CdS shows an excellent photocatalytic hydrogen evolution rate of 943.54 µmol h-1 g-1 and a rhodamine B photocatalytic degradation rate of 99.1% in 60 min, which is superior to the photocatalysis of pure CdS prepared by many other methods.
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In the present study, a magnetically separable adsorbent, manganese ferrite (MnFe2O4)/sugarcane bagasse biochar magnetic composites (MFSCBB-MCs), was fabricated through a one-step pyrolysis method. The characterization of the prepared adsorbents indicated that MnFe2O4 nanoparticles were successfully embedded into the biochar matrix, offering magnetic separability and increasing the negative charges on the surface relative to the pristine biochar. Batch adsorption tests indicated that the adsorption of lead on MFSCBB-MCs was pH- and dose-dependent. The experimental results were effectively fitted using the pseudo-second-order kinetic model (R 2 > 0.99) and the Langmuir isotherm equation (R 2 > 0.99), indicating the main chemisorption pathway and monolayer coverage process. Meanwhile, lead adsorption was found to be spontaneous and endothermic, as shown by the study of thermodynamic parameters. The maximum capacity, q m, calculated from the Langmuir model was 155.21 mg·g-1 at 25 °C, demonstrating excellent adsorption capability compared with several previously reported bagasse adsorbents. Based on adsorption mechanism analysis, physical adsorption, electrostatic attraction, and complexation were all involved in the lead(II) adsorption process on MFSCBB-MCs. Furthermore, the adsorbent was easily regenerated as indicated by the high magnetic separation and chemical desorption potential after five cycles, so it is a cost-effective and environmentally favorable adsorbent for wastewater lead removal.
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This is the first time to report a facile strategy to fabricate galactoglucomannan-based latex with highly transparent, hydrophobic and flexible characteristics by combining etherification with subsequent emulsion polymerization. The allylated galactoglucomannans (A-GGM) and galactoglucomannan-based latexes (GGM-L) were prepared and their chemical structure, substitution degree, molecular weight, conversion rate, particle size and zeta potential were characterized by ATR-FTIR, 1HNMR, quantitative 13CNMR, HP-SEC, HPLC and zeta-sizer nanometer analyzer, respectively. Furthermore, the effects of substitution degree on film surface roughness and homogeneity, water vapor permeability (WVP) and thermal stability were evaluated by AFM, SEM, WVP and TGA, respectively. The optimal GGM-L film exhibited 91.3% transmittance and 0.43% haze, 117° water contact angle, 31.2% elongation at break and 30.9 MPa ultimate tensile stress. The bio-based content of the GGM-L may reach about 99 wt%, which provides a promising avenue for polyolefin-based latex replacement for paper and paperboard applications.
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Látex , Mananos , Emulsiones , Látex/química , Mananos/química , PolimerizacionRESUMEN
A water-soluble, stable, simple and dual ligands (bovine serum albumin and L-histidine)-enhanced copper nanoclusters (BSA-CuNCs@L-His) was synthesized by one-step wet chemical method. Interestingly, the introduction of L-His ligand could improve evidently the quantum yields (QYs, 3.47%) and stability of BSA-CuNCs due to forming the stronger interaction of L-His and Cu and producing bigger diameter CuNCs by coordination-induced aggregation. Thus, a new ratiometric fluorescent probe (RF-probe) was successfully exploited for sensitively and selectively mensurating doxycycline (DOX) because DOX could simultaneously regulate the fluorescence (FL) intensities of BSA-CuNCs@L-His at 410 and 520 nm. The FL quenching of BSA-CuNCs@L-His at 410 nm by DOX was mainly originated from the static quenching process, while DOX could bind to Trp-212 in BSA from the skeleton of BSA-CuNCs@L-His by electrostatic interaction causing the appearance of new emission peak at 520 nm. The content of DOX was monitored by the RF-probe with a linear range of 0.05-14.0 µM and a LOD (limit of detection) and LOQ (limit of quantification) of 6.4 and 21.3 nM (at 3σ/slope and 10σ/slope). Moreover, compared to the standard HPLC method, the proposed RF-probe was extended to the detection of DOX in doxycycline hydrochloride (DOXH) tablets, DOXH injections and DOXH capsules with satisfactory results.
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Nanopartículas del Metal , Preparaciones Farmacéuticas , Cobre , Doxiciclina , Colorantes Fluorescentes , Ligandos , Límite de Detección , Espectrometría de FluorescenciaRESUMEN
Electrocatalytic nitrite (NO2-) reduction to ammonia (NH3) can not only synthesize value-added NH3, but also remove NO2- pollutants from the environment. However, the low efficiency of NO2--to-NH3 conversion hinders its applications. Here, Ni nanoparticle-decorated juncus-derived biomass carbon prepared at 800 °C (Ni@JBC-800) serves as an efficient catalyst for NH3 synthesis by selective electroreduction of NO2-. This catalyst shows a remarkable NH3 yield of 4117.3 µg h-1 mgcat.-1 and a large faradaic efficiency of 83.4% in an alkaline electrolyte. The catalytic mechanism is further investigated by theoretical calculations.
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A stable, water-soluble, heightened quantum yields (QYs) Au nanoclusters by the alliance between doping Ag and dual ligands (thiosalicylic acid and bovine serum albumin) (TSA/BSA-Au/AgNCs) was prepared using one-step wet chemical synthesis. The effect of different types of aromatic thiols and the molar ratio of Au-Ag on the photo-luminescence performance of AuNCs was discussed in detail. The alloy NCs is shown to be viable fluorescent method for vitamin B12 (VB12) and chlortetracycline hydrochloride (CCH) assays, and become an excellent temperature sensor in the range of 10-50 °C. The fluorescence (FL) of TSA/BSA-Au/AgNCs was quenched with the addition of VB12 or CCH coming from Förster resonance energy transfer (FRET) combined with inner filter effect (IFE). The method can detect VB12/CCH by fluorometry with a linear response in the range of 0.33-60.0/0.33-60.0 µmol·L-1 and a 71.0/64.0 nmol·L-1 detection limit (at 3σ/slope). Furthermore, the proposed method was extended to the assays of VB12 in mineral water or tablets and CCH in veterinary drug or ointment with satisfactory results.
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Clortetraciclina , Nanopartículas del Metal , Colorantes Fluorescentes , Oro , Ligandos , Albúmina Sérica Bovina , Espectrometría de Fluorescencia , Vitamina B 12RESUMEN
The safe and effective capture and storage of iodine from nuclear waste is of great significance in industry. This article reports the preparation of a series of millimeter-sized ZIF-8@polyacrylonitrile composite beads with high specific surface area and porosity by the phase inversion method for iodine capture. The composite beads showed a higher capture capacity (4150 mg g-1) under excess iodine vapor. The amount of iodine adsorbed in the organic solution is also as high as 643 mg g-1, and the adsorption conforms to the Freundlich isotherm and the pseudo-second-order kinetic model. Moreover, composite beads also exhibit higher thermal stability (310 °C). Therefore, ZIF-8@polyacrylonitrile composite beads show great potential as a material for capturing and temporarily storing radioactive iodine.
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Two novel pentanorcucurbitane triterpenes, 22-hydroxy-23,24,25,26,27-pentanorcucurbit-5-en-3-one (1) and 3,7-dioxo-23,24,25,26,27-pentanorcucurbit-5-en-22-oic acid (2) together with a new trinorcucurbitane triterpene, 25,26,27-trinorcucurbit-5-ene-3,7,23-trione (3) were isolated from the methyl alcohol extract of the stems of Momordica charantia. The structures of the new compounds were elucidated by spectroscopic methods. Compounds 2 and 3 showed potent cytoprotective activity in tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity of HepG2 cells.