Here, a bifunctional DNAzyme nanodevice (BFDN) with two detection paths toward the same target was intelligently designed and applied to construct a ratiometric electrochemical biosensor for highly ...reliable and sensitive mercury ion (Hg2+) detection. In the presence of the target Hg2+, the T-Hg2+-T pair could actuate the preassembled DNA four-branched nanostructure (DNA-4B) without cleavage capability transform to the BFDN with strong cleavage capability for triggering two synchronous Hg2+ detection paths, including a “signal-off” path (1) that consisted of a cascade DNAzyme cleavage reaction to dramatically decrease the ferrocene (Fc) response and a “signal-on” path (2) that accomplished the capture of significant amounts of methylene blue (MB) on the electrode surface under the assistant of DNAzyme2 (D2) in BFDN. This strategy not only effectively avoided the false positive signal compared with traditional single paths, but also proposed a new ratiometric method to successfully circumvent the deficiency that existed in previous ratiometric electrochemical biosensors. As a result, the reliable and sensitive Hg2+ detection was achieved in the range from 0.1 pM to 200 nM with a detection limit of 23 fM. Above all, here, the assembly of the BFDN is ingeniously coupled with amplification strategy, paving a promising avenue to promote the performances of simple multifunctional DNA nanomachines and facilitate the corresponding development of DNA nanomachines in biosensor platform.
Radiative cooling is a zero-energy technology that enables subambient cooling by emitting heat into outer space (~3 K) through the atmospheric transparent windows. However, existing designs typically ...focus only on the main atmospheric transparent window (8-13 μm) and ignore another window (16-25 μm), under-exploiting their cooling potential. Here, we show a dual-selective radiative cooling design based on a scalable thermal emitter, which exhibits selective emission in both atmospheric transparent windows and reflection in the remaining mid-infrared and solar wavebands. As a result, the dual-selective thermal emitter exhibits an ultrahigh subambient cooling capacity (~9 °C) under strong sunlight, surpassing existing typical thermal emitters (≥3 °C cooler) and commercial counterparts (as building materials). Furthermore, the dual-selective sample also exhibits high weather resistance and color compatibility, indicating a high practicality. This work provides a scalable and practical radiative cooling design for sustainable thermal management.
Due to the specificity, high efficiency, and gentleness of enzyme catalysis, the industrial utilization of enzymes has attracted more and more attention. Immobilized enzymes can be recovered/recycled ...easily compared to their free forms. The primary benefit of immobilization is protection of the enzymes from harsh environmental conditions (e.g., elevated temperatures, extreme pH values, etc.). In this paper, catalase was successfully immobilized in a poly(aryl ether sulfone) carrier (PAES-C) with tunable pore structure as well as carboxylic acid side chains. Moreover, immobilization factors like temperature, time, and free-enzyme dosage were optimized to maximize the value of the carrier and enzyme. Compared with free enzyme, the immobilized-enzyme exhibited higher enzymatic activity (188.75 U g−1, at 30 °C and pH 7) and better thermal stability (at 60 °C). The adsorption capacity of enzyme protein per unit mass carrier was 4.685 mg. Hydrogen peroxide decomposition carried out in a continuous-flow reactor was selected as a model reaction to investigate the performance of immobilized catalase. Immobilized-enzymes showed a higher conversion rate (90% at 8 mL/min, 1 h and 0.2 g) compared to intermittent operation. In addition, PAES-C has been synthesized using dichlorodiphenyl sulfone and the renewable resource bisphenolic acid, which meets the requirements of green chemistry. These results suggest that PAES-C as a carrier for immobilized catalase could improve the catalytic activity and stability of catalase, simplify the separation of enzymes, and exhibit good stability and reusability.
The conventional double cropping system of winter wheat and summer maize (WW-SUM) in the North China Plain (NCP) consumes a large amount of water and chemical fertilizer, threatening the sustainable ...development of agriculture in this region. This study was based on a three-year field experiment of different cropping systems (2H1Y-two harvests in one year; 3H2Y-three harvests in two years; and 1H1Y-one harvest in one year). The 2H1Y system had three irrigation-fertilization practices (FP-farmer's practice; RI-reduced input; and WQ-Wuqiao pattern in Wuqiao County, Hebei Province). A soil-crop system model (WHCNS-soil water heat carbon nitrogen simulator) was used to quantify the effects of different cropping systems on water and nitrogen use efficiencies (WUE and NUE, respectively), and to explore the trade-offs between crop yields and environmental impacts. The results showed that annual yield, water consumption, and the WUE of 2H1Y were higher than those of the 3H2Y and 1H1Y systems. However, local precipitation during the period of crop growth could only meet 65%, 76%, and 91% of total water consumption for the 2H1Y, 3H2Y and 1H1Y systems, respectively. Nearly 65% of irrigation water (groundwater) was used in the period of wheat growth that contributed to almost 40% of the annual yield. Among the three patterns of the 2H1Y system, the order of the WUE was 2H1Y_RI > 2H1Y_WQ > 2H1Y_FP. Compared to 2H1Y_FP, the total fertilizer N application rates in 2H1Y_WQ, 2H1Y_RI, and 3H2Y were reduced by 25%, 65%, and 74%, respectively. The 3H2Y system had the highest NUE of 34.3 kg kg
, 54% greater than the 2H1Y_FP system (22.2 kg kg
). Moreover, the 3H2Y system obviously reduced nitrate leaching and gaseous N loss when compared with the other two systems. The order of total N loss of different cropping systems was 2H1Y (261 kg N ha
) > 1H1Y (78 kg N ha
) > 3H2Y (70 kg N ha
). Considering the agronomic and environmental effects as well as economic benefits, the 3H2Y cropping system with optimal irrigation and fertilization would be a promising cropping system in the NCP that could achieve the balance between crop yield and the sustainable use of groundwater and N fertilizer.
The European Union (EU) emergency call (eCall) employs the GSM voice channel for vehicle emergency data transmission. However, fading statistics of the GSM voice channel after power control has not ...been discussed previously. This paper reports the power measurements for the end-to-end GSM voice channel with an in-vehicle system (IVS) transmitter in laboratory or on freeway. The data reveals that strong fading still exists in the GSMvoice channel after power control, which can cause severe packet loss and delay in the emergency call.
The S-doped PtMn concave cubes enclosed with high index facet and regulatable surface strain are successfully fabricated by two steps hydrothermal method. The PtMnS1.1 catalyst exhibits superior ...catalytic properties for ethanol electrooxidation reaction in acidic and alkaline media, which is ascribed to the optimal surface strain and unsaturated surface-active sites.
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Surface strain engineering has proven to be an efficient strategy to enhance catalytic properties of platinum (Pt)-based catalysts for electrooxidation reactions. Herein, the S-doped PtMn concave cubes (CNCs) enclosed with high index facets (HIFs) and regulatable surface strain are successfully fabricated by two steps hydrothermal method. The S element with electrophilic property can modify the near-surface of PtMn nanocrystals, altering the electronic structure of Pt to effectively regulate the adsorption/desorption of intermediates in the ethanol electrooxidation reaction (EOR). The PtMnS1.1 catalyst with optimal surface strain delivered extraordinary catalytic performance on EOR in acidic media, with a specific activity of 2.88 mA/cm2 and mass activity of 1.10 mA/μgPt, which is 4.1 and 2.2 times larger than that of state-of-the-art Pt/C catalyst, respectively. Additionally, the PtMnS1.1 catalyst also achieve excellent catalytic properties in alkaline electrolyte for EOR. The results of kinetic studies indicated that the surface strain and modified electronic structure can degrade the activation energy barrier during the process of EOR, which is beneficial for enhance the reaction rate. This work provides a promising approach to construct highly efficient electrocatalysts with tunable surface strain effects for clean energy electro-chemical reactions.
In this work, a novel DNA circle capture probe with multiple target recognition domains was designed to develop an electrochemical biosensor for ultrasensitive detection of microRNA-21 (miRNA-21) and ...miRNA-155 simultaneously. The DNA circle capture probe was anchored at the top of the tetrahedron DNA nanostructure (TDN) to simultaneously recognize miRNA-21 and miRNA-155 through multiple target recognition domains under the assistance of Helper strands, which could trigger mimetic proximity ligation assay (mPLA) for capturing the beacons ferrocene (Fc)-A1 and methylene blue (MB)-A2 to achieve multiple miRNAs detection. In this way, the local reaction concentration could be enhanced and avoid the interference of various capture probes compared with the traditional multiplexed electrochemical biosensor with the use of different capture probes, resulting in the significantly improvement of detection sensitivity. As a result, this proposed biosensor showed wide linearity ranging from 0.1 fM to 10 nM with detection limits of miRNA-21 and miRNA-155 as 18.9 aM and 39.6 aM respectively, which also could be applied in the simultaneously detection of miRNA-21 and miRNA-155 from cancer cell lysates. The present strategy paved a new path in the design of capture probes for achieving more efficient and sensitive multiple biomarkers detections and possessed the potential applications in clinical diagnostic of diseases.
•The detection efficiency was improved due to different miRNAs could be monitored in one DNA circle capture probe.•The TDN enhanced the uniformity of capture probe distribution on the electrode for improving the detection sensitivity.•The electrochemical biosensor showed low detection limits of 18.9 aM and 39.6 aM for miRNA-21 and miRNA-155 respectively.
In this work, a DNA three-way junction (TWJ) with multiple recognition regions was intelligently engineered, which could be applied as an unconfined DNA walker with a rapid walking speed and high ...sensitivity for electrochemical detection of microRNA (miRNA-182-5p). Once the target miRNA was presented, the hairpins on TWJ could be successively opened to form an annular DNA walker, which could walk on the entire scope of the electrode surface without the confine for the length of DNA walker legs compared with the traditional DNA walker, greatly improving the walking efficiency. In addition, this DNA walker with multirecognition segments could obviously increase the local concentration of recognition sites, which significantly enhanced the detection speed and sensitivity. As a result, this proposed biosensor with annular DNA as a walker could dexterously achieve the ultrasensitive and fast detection of miRNA-182-5p from 0.1 fM to 1 nM with a detection limit of 31.13 aM. Meaningfully, this strategy explored an innovative path in the design of a new DNA walker nanostructure for accomplishing speedy and sensitive detection of biomarkers.
In this work, the highly efficient target recycling-based netlike Y-shaped DNA (Y-DNA), which regulated the electrocatalysis of Fe3O4@CeO2–Pt nanoparticles (Fe3O4@CeO2–PtNPs) toward methylene blue ...(MB) for signal amplification, was developed to prepare a sensitive DNA biosensor for detecting the DNA associated with oral cancer. Specifically, with the help of highly efficient enzyme-assisted target recycling (EATR) amplification strategy, one target DNA input was converted to corresponding plenty of DNA strands S1Fe3O4@CeO2–Pt and S2MB output, which could be employed to interact with HP2 immobilized on the electrode surface to form stable netlike Y-DNA without any waste of recycling products. Meanwhile, the formation of netlike Y-DNA could regulate electrocatalytic efficiency of Fe3O4@CeO2–PtNPs, inducing the proximity of Fe3O4@CeO2–PtNPs to MB and significantly enhancing electrochemical signal. Further, the signal could also be amplified by Fe3O4@CeO2–PtNPs modified on the electrode surface. By virtue of this ingenious design, a novel netlike Y-DNA structure based on highly efficient EATR was simply constructed and successfully applied to an electrochemical DNA biosensor along with electrocatalysis of Fe3O4@CeO2–PtNPs, achieving the sensitive detection of target DNA ranging from 10 fM to 50 nM with a detection limit of 3.5 fM. Impressively, the biosensor here demonstrates an admirable method for regulating the electrocatalysis of NPs toward substrates to enhance signal, and we believe that this biosensor is a potential candidate for the sensitive detection of target DNA or other disease-related nucleic acids.
