A fluorescent biosensor was developed for Cd2+ detection based on a Cd2+-fueled wheel DNAzyme walker. Cd2+ can activate the wheel to roll along the DNA walking tracks through DNAzyme cleavage and ...toehold-mediated strand displacement. The substrate strand was modified with BHQ and Cy5. Through continuous cleavage reactions toward the substrate strands, a high fluorescence signal can be obtained. The biosensor is ultrasensitive, and the detection limit is 0.2 pM (S/N = 3). The fluorescent assay is robust and has been applied to the determination of Cd2+ in real water samples with good accuracy and reliability. Using Cd2+, Pb2+, and Hg2+ as the three inputs, we also construct a concatenated AND logic gate. The input combination of (111) can produce an output of 1. Other input combinations produce an output of 0. Our proposed detection platform and logic system hold great promise for the ultrasensitive and intelligent sensing of different heavy metal ions in water samples.
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•An ultrasensitive biosensor was built for Cd2+ detection in water samples.•Cd2+-fueled wheel DNAzyme walker was used to realize the signal amplification.•The detection limit of the biosensor is 0.2 pM.•Using Cd2+, Pb2+, and Hg2+ as the three inputs, we also construct a concatenated AND logic gate.
•The BPA-aptamer binding activates a DNA circuit for signal amplification.•The assay is sensitive, with a detection limit of 50 fM.•The assay is selective and robust.•The biosensor can work in milk ...samples with satisfactory recovery and accuracy.
As bisphenol A (BPA) is harmful to human health, it is of great significance to develop a new method for BPA detection. Herein, we designed a BPA biosensor by integrating an amplifying DNA circuit with Mg2+-dependent DNAzyme into the sensing system. The BPA-aptamer binding activated a DNA circuit for signal amplification based on toehold-mediated strand displacement. A catalytic Mg2+-dependent DNAzyme was formed through synergistically DNA hybridization, which can cleave the dual-labeled substrate DNA into two segments. The separation of the fluorophore and quencher produces a high fluorescence response for BPA detection. This biosensor exhibited a superior sensitivity with a detection limit of 50 fM. The method is selective and robust, which can work even in milk samples with satisfactory accuracy. The biosensor analytical results were also verified by liquid chromatography coupled with mass spectrometry (LC–MS) and no obvious difference existed between the two methods.
Organic–inorganic metal halide perovskites (most notably CH3NH3PbI3) have demonstrated remarkable physical attributes for photovoltaic and diverse optoelectronic applications, whereas concerns about ...toxicity owing to the use of lead in the chemical composition still motivate further exploration of new, nontoxic candidates. Lead‐free halide double perovskites (HDPs), designed by the rational chemical substitution of Pb2+ with other nontoxic candidate elements, have recently attracted interest as a fascinating alternative to their Pb‐based counterparts. Herein, recent advances in crystal structures, physical properties, and versatile optoelectronic applications of lead‐free HDPs, such as solar cells, photodetectors, X‐ray detectors, and light‐emitting diodes, are reviewed. Perspectives to improve the physical and photoelectric properties of existing HDP materials are also discussed and will favor future development of new, lead‐free HDP candidates.
Safety first! Halide double perovskites (HDPs) are a fascinating class of candidates for diverse optoelectronic applications. The physical and photoelectric properties of HDPs, including crystal structures, theoretical calculations, and synthetic methods are summarized. The device applications, current challenges, and perspectives are also discussed.
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•1. Single-atom Co modified g-C3N4 prepared by one-step thermal-polymerization of cobalt phthalocyanine (CoPc) and urea.•2. Strong interaction between Co 3d electrons and C 2p ...electrons of CO2 activate C = O bonds in CO2 molecule.•3. Optimal 1%Co-CN sample exhibits higher CO yield of 94.9 umol/g/h than pure g-C3N4 0.25 umol/g/h.
Using solar energy to realize photoreduction of CO2 into valuable chemicals is a potential way to solve energy crisis and carbon cycle. Due to the extremely stable molecular configuration of CO2, activating CO2 molecule is the key and difficult step in the whole CO2 conversation process. In this work, we used density functional theory (DFT) to calculate the reaction pathways of CO2 to CO on pure g-C3N4 and single-atom cobalt (Co) modified g-C3N4. Theoretical calculation predicts that single-atom Co sites modified g-C3N4 (Co-CN) possess stronger CO2 adsorption ability and lower barrier of CO2 hydrogenation activation than pure g-C3N4. The strong interaction between Co 3d electrons and C 2p electrons of CO2 is the crucial factor to activate C = O bonds of CO2 molecule. Better CO2 adsorption and activation abilities also are proved in Co-CN by CO2 adsorption, temperature programmed desorption (TPD), and sensor tests. As a result, the optimal 1%Co-CN exhibits higher CO yield of 94.9 umol/g/h than pure g-C3N4 (0.25 umol/g/h). This work provides a new insight of the role of single-atom sites in CO2 reduction reactions.
A complete set of binary basic logic gates (OR, AND, NOR, NAND, INHIBT, IMPLICATION, XOR and XNOR) is realized on a label-free and enzyme-free sensing platform using caged G-quadruplex as the signal ...transducer. In the presence of an appropriate input, the temporarily blocked G-rich sequence in the hairpin DNA is released through cleavage by the synergetically-stabilized Mg
-dependent DNAzyme which can be made to function
the input-guided cooperative conjunction of the DNAzyme subunits. In the presence of hemin, the unblocked G-quadruplex DNAzyme catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H
O
to generate a colored readout signal which can be readily distinguished by the naked eye. This strategy is quite versatile and straightforward for logic operations. Two combinatorial gates (XOR + AND and XOR + NOR) are also successfully fabricated to demonstrate the modularity and scalability of the computing elements. The distinctive advantage of this logic system is that molecular events in aqueous solution could be translated into a color change which can be directly observed by the naked eye without resorting to any analytical instrumentation. Moreover, this work reveals a new route for the design of molecular logic gates that can be executed without any labeling and immobilization procedure or separation and washing step, which holds great promise for intelligent point-of-care diagnostics and in-field applications.
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•A novel LNG-LHS-ORC-DC system for cascade utilization of LNG cold energy is proposed.•Multi-objective optimization based on NSGA-II is performed.•The utilization of LNG cold energy ...by each subsystem is investigated.•Exergy destructions of all components are analyzed to find system improvement scheme.•Economic feasibility of the proposed system is studied based on net present value.
To effectively recover the cold energy released in the liquefied natural gas (LNG) regasification process, this paper constructs a novel LNG cold energy cascade integrated utilization system. In the system, the LNG cold energy in low temperature zone is used for light hydrocarbon separation (LHS), and the remaining cold energy is divided into two parts. One part is used for organic Rankine cycle (ORC) as well as data center cooling (DCC), and the other part is used for cold warehouse cooling (CWC). The thermodynamic and economic analysis of the system is carried out in detail, and the multi-objective optimization based on NSGA-II is implemented to investigate the optimal performance. The results show that the net power output of the system is 4259.72 kW, much larger than that of the LNG cold energy single utilization system for LHS in reference, and the cold energy for data center and cold warehouse is equivalent to saving 12685.87 kW electric energy. Furthermore, the revenue of the system in 20 years is 2.9982 × 109 $, more than that of the reference system. Through the net present value analysis, it is found that the system is more sensitive to the ethane price than to electric price.
An enzyme-free DNA circuit was designed for the amplified detection of Cd
2+
based on hairpin probe-mediated toehold binding and branch migration. A Cd
2+
-specific aptamer was used to recognize Cd
...2+
and a G-quadruplex was used to report the detection signal. The assay is sensitive, with a detection limit of 5 pM.
A sensitive Cd
2+
biosensor was fabricated on a DNA circuit using an aptamer as the recognition probe and a G-quadruplex as the reporter.
The molecular pathology of multi-organ injuries in COVID-19 patients remains unclear, preventing effective therapeutics development. Here, we report a proteomic analysis of 144 autopsy samples from ...seven organs in 19 COVID-19 patients. We quantified 11,394 proteins in these samples, in which 5,336 were perturbed in the COVID-19 patients compared to controls. Our data showed that cathepsin L1, rather than ACE2, was significantly upregulated in the lung from the COVID-19 patients. Systemic hyperinflammation and dysregulation of glucose and fatty acid metabolism were detected in multiple organs. We also observed dysregulation of key factors involved in hypoxia, angiogenesis, blood coagulation, and fibrosis in multiple organs from the COVID-19 patients. Evidence for testicular injuries includes reduced Leydig cells, suppressed cholesterol biosynthesis, and sperm mobility. In summary, this study depicts a multi-organ proteomic landscape of COVID-19 autopsies that furthers our understanding of the biological basis of COVID-19 pathology.
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•11,394 proteins are quantified in autopsy samples from 7 organs in 19 COVID-19 patients•Elevated expression of cathepsin L1 is detected in the COVID-19 lung tissue•Dysregulation of angiogenesis, coagulation, and fibrosis is detected in multiple organs•Systemic metabolic dysregulation is detected in multiple organs
A proteomics analysis of 144 autopsy samples from seven organs in 19 COVID-19 patients shows elevated expression of cathepsin L1, rather than ACE2, in the lung tissue and highlights dysregulation of angiogenesis, coagulation, and fibrosis in multiple organs, in addition to systemic hyperinflammation.
An enzyme-free DNA circuit was designed for the amplified detection of Cd2+ based on hairpin probe-mediated toehold binding and branch migration. A Cd2+-specific aptamer was used to recognize Cd2+ ...and a G-quadruplex was used to report the detection signal. The assay is sensitive, with a detection limit of 5 pM.
In this work, an enzyme-free biosensor is reported for mycotoxin detection based on a toehold-mediated catalytic hairpin assembly (CHA) and a DNAzyme-cascaded hydrolysis reaction. In the presence of ...a mycotoxin, the recognition between an aptamer and the mycotoxin releases the trigger DNA. The trigger DNA initiates the toehold-mediated CHA, generating large amounts of partial duplex B/C with four toeholds, which can be used to assemble the DNAzyme-cascaded hydrolysis reaction. Furthermore, through a collaborative autoassembly reaction among the B/C duplex, DNA1, and DNA2, supramolecular nanostructures corresponding to Mg2+-dependent DNAzymes can be formed. With the incubation of Mg2+, the dual-modified (TAMRA/BHQ2) substrate strand DNA2 will be cleaved into two fragments, yielding a high TAMRA fluorescence signal for mycotoxin testing. Under optimal conditions, the sensing system was ultrasensitive and showed low detection limits of 0.2 pM for ochratoxin A (OTA), 0.13 pM for aflatoxin B1 (AFB1), and 0.17 pM for zearalenone (ZEN). The mycotoxin aptasensor also exhibited high selectivity and was successfully applied for the quantitative analysis of OTA, AFB1, and ZEN in wine samples. Due to the advantages of flexibility and versatility, this mycotoxin platform was used to fabricate several concatenated logic gates including “AND–INHIBIT”, “INHIBIT–OR”, “OR–AND”, and “OR–INHIBIT” logic biocomputings. Such multiple functions of the logic system provided a universal sensing strategy for the intelligent detection of multiplex mycotoxins, demonstrating considerable potential in food safety and environmental monitoring.
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