As a critical topic of international concern, food safety has received great attention in recent years. The hazardous substances (such as antibiotics, heavy metal ions, food additives, and foodborne ...bacteria) in foodstuffs would cause threat to human health and economic losses in food industry. Despite of high sensitivity, accuracy, and reliability of conventional techniques for analysis of food contaminants, they often require complicated apparatus, well-trained personalized operation, and laborious and time-consuming procedure. In this regard, new sensing strategies for convenient, fast, and sensitive detection of food contaminants should be developed for food safety.
Metal–organic frameworks (MOFs), as a large category of porous crystalline materials, could be used as efficient platforms for constructing diverse chemosensors and biosensors, for their high porosity, adjustable compositions or structures, and good stability. A variety of MOFs, MOFs-based composites, and MOFs-based derivatives show excellent fluorescence (FL), chemical functionality, and strong bioaffinity toward probes (DNA, aptamers, or antibodies), exhibiting great potentials as FL emitters, electrode materials, or platforms of biosensors for selective and sensitive detection of hazard analytes in foodstuffs. By coupling with different determination techniques such as FL, electrochemical (EC), photoelectrochemical (PEC) or surface-enhanced Raman spectroscopy methods, MOFs-based materials have shown promising applications for detecting diverse analytes. Furthermore, the current challenges and future developments of MOFs-based materials for analysis of food contaminants have been discussed.
Although some reviews on the applications of MOFs in food packing and food safety have been documented, this comprehensive review will provide new insights to the construction of chemosensors and biosensors with MOFs-based materials for determination of food contaminants toward food safety monitoring.
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•A comprehensive review on MOFs-based chemosensors/biosensors for food safety.•Discussion on the determination platforms and techniques for food contaminants.•Development of MOFs-based chemosensors/biosensors for various food contaminants.
Plant disease resistance genes (R genes) encode proteins that function to monitor signals indicating pathogenic infection, thus playing a critical role in the plant's defense system. Although many ...studies have been performed to explore the functional details of these important genes, their origin and evolutionary history remain unclear.
In this study, focusing on the largest group of R genes, the nucleotide-binding site–leucinerich repeat (NBS-LRR) genes, we conducted an extensive genome-wide survey of 38 representative model organisms and obtained insights into the evolutionary stage and timing of NBS-LRR genes.
Our data show that the two major domains, NBS and LRR, existed before the split of prokaryotes and eukaryotes but their fusion was observed only in land plant lineages. The Toll/interleukin-1 receptor (TIR) class of NBS-LRR genes probably had an earlier origin than its nonTIR counterpart. The similarities of the innate immune systems of plants and animals are likely to have been shaped by convergent evolution after their independent origins.
Our findings start to unravel the evolutionary history of these important genes from the perspective of comparative genomics and also highlight the important role of reorganizing pre-existing building blocks in generating evolutionary novelties.
The identifiable target effect refers to the preference for helping identified victims and punishing identifiable perpetrators compared with equivalent but unidentifiable counterparts. The ...identifiable target effect is often attributed to the heightened moral emotions evoked by identified targets. However, the specific neurocognitive processes that mediate and/or modulate this effect remain largely unknown. Here, we combined a third-party punishment game with brain imaging and computational modeling to unravel the neurocomputational underpinnings of the identifiable transgressor effect. Human participants (males and females) acted as bystanders and punished identified or anonymous wrongdoers. Participants were more punitive toward identified wrongdoers than anonymous wrongdoers because they took a vicarious perspective of victims and adopted lower reference points of inequity (i.e., more stringent norms) in the identified context than in the unidentified context. Accordingly, there were larger activity of the ventral anterior insula, more distinct multivariate neural patterns in the dorsal anterior insula and dorsal anterior cingulate cortex, and lower strength between ventral anterior insula and dorsolateral PFC and between dorsal anterior insula and ventral striatum connectivity in response to identified transgressors than anonymous transgressors. These findings implicate the interplay of expectancy violations, emotions, and self-interest in the identifiability effect. Last, individual differences in the identifiability effect were associated with empathic concern/social dominance orientation, activity in the precuneus/cuneus and temporo-parietal junction, and intrinsic functional connectivity of the dorsolateral PFC. Together, our work is the first to uncover the neurocomputational processes mediating identifiable transgressor effect and to characterize psychophysiological profiles modulating the effect.
The identifiable target effect, more help to identified victims or stronger punishment to identifiable perpetrators, is common in daily life. We examined the neurocomputational mechanisms mediating/modulating the identifiability effect on third-party punishment by bridging literature from economics and cognitive neuroscience. Our findings reveal that identifiable transgressor effect is mediated by lower reference points of inequity (i.e., more stringent norms), which might be associated with a stronger involvement of the emotion processes and a weaker engagement of the analytic/deliberate processes. Furthermore, personality traits, altered brain activity, and intrinsic functional connectivity contribute to the individual variance in the identifiability effect. Overall, our study advances the understanding of the identifiability effect by shedding light on its component processes and modulating factors.
A new core–shell nanostructured composite composed of Fe(III)-based metal–organic framework (Fe-MOF) and mesoporous Fe3O4@C nanocapsules (denoted as Fe-MOF@mFe3O4@mC) was synthesized and developed as ...a platform for determining trace heavy metal ions in aqueous solution. Herein, the mFe3O4@mC nanocapsules were prepared by calcining the hollow Fe3O4@C that was obtained using the SiO2 nanoparticles as the template, followed by composing the Fe-MOF. The Fe-MOF@mFe3O4@mC nanocomposite demonstrated excellent electrochemical activity, water stability and high specific surface area, consequently resulting in the strong biobinding with heavy-metal-ion-targeted aptamer strands. Furthermore, by combining the conformational transition interaction, which is caused by the formation of the G-quadruplex between a single-stranded aptamer and high adsorbed amounts of heavy metal ions, the developed aptasensor exhibited a good linear relationship with the logarithm of heavy metal ion (Pb2+ and As3+) concentration over the broad range from 0.01 to 10.0nM. The detection limits were estimated to be 2.27 and 6.73 pM toward detecting Pb2+ and As3+, respectively. The proposed aptasensor showed good regenerability, excellent selectivity, and acceptable reproducibility, suggesting promising applications in environment monitoring and biomedical fields.
•A core–shell nanostructured Fe-MOF@mFe3O4@mC-based aptasensor was constructed.•High sensitivity, selectivity and low detection limit of the developed aptasensor.•Ultra-sensitively detecting trace heavy metal ions in river water and human serum.
Conductive polymers are recognized as ideal candidates for the development of noninvasive and wearable sensors for real‐time monitoring of potassium ions (K+) in sweat to ensure the health of life. ...However, the low ion‐to‐electron transduction efficiency and limited active surface area hamper the development of high‐performance sensors for low‐concentration K+ detection in the sweat. Herein, a wearable K+ sensor is developed by tailoring the nanostructure of polypyrrole (PPy), serving as an ion‐to‐electron transduction layer, for accurately and stably tracing the K+ fluctuation in human sweat. The PPy nanostructures can be tailored from nanospheres to nanofibers by controlling the supramolecular assembly process during PPy polymerization. Resultantly, the ion‐to‐electron transduction efficiency (17‐fold increase in conductivity) and active surface area (1.3‐fold enhancement) are significantly enhanced, accompanied by minimized water layer formation. The optimal PPy nanofibers‐based K+ sensor achieved a high sensitivity of 62 mV decade−1, good selectivity, and solid stability. After being integrated with a temperature sensor, the manufactured wearable sensor realized accurate monitoring of K+ fluctuation in the human sweat.
The polypyrrole (PPy) nanostructures are tailored from nanospheres to nanofibers via controlling the supramolecular assembly process, which is utilized as the ion‐to‐electron conductive layer. Resultantly, the ion‐to‐electron transduction efficiency and active surface area are significantly enhanced, accompanied by minimized water layer formation. The optimal PPy nanofiber‐based potassium ion (K+) sensor achieved a high sensitivity of 62 mV decade−1, good selectivity, and solid stability.
A cage-based anionic Na(i)-organic framework with a unique Na
cluster-based secondary building unit and a cage-in-cage structure was constructed. The selective separation of dyes with different ...charges and sizes was investigated. Furthermore, the Rh6G@MOF composite could be applied as a recyclable fluorescent sensor for detecting picric acid (PA) with high sensitivity and selectivity.
A terbium( iii ) lanthanide–organic framework (534-MOF-Tb) with a green-emission signal was successfully obtained by the solvothermal reaction of Tb 3+ ions with the organic ligand H 3 TBOT ...(2,4,6-tris1-(3-carboxylphenoxy)ylmethylmesitylene). 534-MOF-Tb contains microporous quadrangle channels with accessible Lewis-base sites and coordinated water molecules, which are feasible to anchor and recognise multifarious analytes. It can serve as a recyclable multi-responsive sensing material for detecting Fe 3+ , MnO 4 − , Cr 2 O 7 2− , and p -nitrotoluene (4-NT). Significantly, this is the first reported MOF-based sensor for detecting explosive 4-NT. Moreover, the mechanism of the selective luminescence quenching response for Fe 3+ , MnO 4 − , Cr 2 O 7 2− or 4-NT can be mainly explained in terms of the competition between the absorption of the light source energy and the electronic interaction between the analyte and the TBOT ligand.
Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amounts of DMSO residual are often seen on the surface of chemical product. It is difficult to ...quickly determine whether the residual DMSO is washed completely. This work reports a CdII metal–organic framework (MOF) SXU‐4 which can detect trace amounts of DMSO in various solvents. Fluorescence experiments reveal its turn‐on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU‐4 (DMSO@SXU‐4), in combination with computational results uncover that the enhanced DMSO–MOF conjugation through multiple DMSO–MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.
Cd‐based MOF SXU‐4 can selectively and sensitively detect trace amount of DMSO in various solvents through a turn‐on based luminescence mechanism. It can be used as luminescent probe for rapid DMSO residual detection.
We report a strategy for stereoselective O‐aryl‐glycoside synthesis by copper‐catalyzed cross‐coupling of a variety of anomeric sugars and (hetero)aromatic iodides. Stereocontrol of the α/β ...selectivity can be successfully realized by slight structural modifications of the oxalic diamide ligands. Mechanistic studies indicated a dynamic kinetic resolution (DKR) reaction mechanism controlled by the ligand structures. This reaction could be performed on gram scale, and has also been applied to the synthesis of some natural products.
A defect‐rich 2D p‐n heterojunction, CoxNi3‐x(HITP)2/BNSs‐P (HITP: 2,3,6,7,10,11‐hexaiminotriphenylene), is constructed using a semiconductive metal–organic framework (MOF) and boron nanosheets ...(BNSs) by in situ solution plasma modification. The heterojunction is an effective catalyst for the electrocatalytic nitrogen reduction reaction (eNRR) under ambient conditions. Interface engineering and plasma‐assisted defects on the p‐n CoxNi3‐x(HITP)2/BNSs‐P heterojunction led to the formation of both Co‐N3 and B…O dual‐active sites. As a result, CoxNi3‐x(HITP)2/BNSs‐P has a high NH3 yield of 128.26 ± 2.27 µg h−1 mgcat.−1 and a Faradaic efficiency of 52.92 ± 1.83% in 0.1 m HCl solution. The catalytic mechanism for the eNRR is also studied by in situ FTIR spectra and DFT calculations. A CoxNi3‐x(HITP)2/BNSs‐P‐based Zn‐N2 battery achieved an unprecedented power output with a peak power density of 5.40 mW cm−2 and an energy density of 240 mA h gzn−1 in 0.1 m HCl. This study establishes an efficient strategy for the rational design, using defect and interfacial engineering, of advanced eNRR catalysts for ammonia synthesis under ambient conditions.
A new type of p‐n type heterojunction is constructed using a semiconductive MOF and boron nanosheets (BNSs) through in situ solution plasma modification. Interface and plasma‐assisted defect engineering endow the heterojunction with multiple active sites, abundant defects, and modulated electronic structures, which show outstanding performance for electrocatalytic ammonia synthesis using a Zn‐N2 battery.
