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Simple and accurate monitoring of urinary dopamine (DA) concentration is significant, which is helpful for the assessment or exclusion of catecholamine-producing tumors, such as pheochromocytoma and paraganglioma. Herein, a fluorescence/colorimetry/smartphone triple-mode sensing platform for DA determination was constructed using copper ion (Cusup2+/sup)-modified hydrazone-linked covalent organic frameworks (Cu-BTA-COF). Cu-BTA-COF with 21.67 wt % copper content exhibited peroxidase-mimic activity. After adding Hsub2/subOsub2/suband 1,3-dihydroxynaphthalene, the Cu-BTA-COF platform can sensitively and selectively detect DA in three modes with consistent results. In fluorescence/colorimetry/smartphone modes, the linear ranges of DA were 1-10, 0.2-40, and 1-10 μM, with related detection limits of 7.2, 8.6, and 23 nM, respectively. Moreover, the Cu-BTA-COF platform can be explored for DA determination in human urine samples with satisfactory recoveries (97.6-100.4%) in all the three modes, suggesting the potential practical application of the Cu-BTA-COF platform for DA detection in urine.

Context Salt stress harms plant growth and limits crop productivity. Autophagy is a material decomposition and metabolism pathway that is central to regulating plant responses to environmental stimuli and may be employed in plant breeding for stress tolerance. The autophagy-related gene ATG8 has become an essential tool for monitoring autophagic activity. Aims We aimed to determine the effects of increased autophagic activity via overexpression of ATG8 on tolerance of wheat (Triticum aestivum L.) seedlings to NaCl stress. Methods Salt-tolerant wheat cv. Jimai22 was used to produce TaATG8a-overexpressing wheat seedlings using Foxtail mosaic virus based virus-mediated overexpression technology. TaATG8a-overexpressing seedlings were exposed to NaCl stress for 6 days. Key results Overexpression of TaATG8a enhanced autophagic activity and improved salt stress tolerance of wheat seedlings. Overexpression of TaATG8a also reduced damage to photosystem II, reduced excess accumulation of reactive oxygen species, increased the activities of superoxide dismutase, peroxidase and catalase, and suppressed programmed cell death in wheat seedling leaves during NaCl treatment. Conclusions Overexpression of TaATG8a conferred higher tolerance of wheat seedlings to NaCl stress and suppressed salt-induced programmed cell death, accompanied by increased autophagic activity. Implications This study provides genetic resources and a theoretical basis for stress tolerance breeding in wheat.

Hexavalent chromium (Cr(vi)) is hazardous and harmful to human health and the ecological environment.

Ratiometric detection of pH is always significant in environmental regulation, medical diagnosis, synthetic chemistry, and beyond. The construction of practical ratiometric pH sensors with reusability is still challenging. Herein, by exploiting a multivariate strategy, we first synthesized and reported a series of novel three-component covalent organic frameworks (COF-COOH

As essential calcium ion (Ca2+) sensors in plants, calcium-dependent protein kinases (CDPKs) function in regulating the environmental adaptation of plants. However, the response mechanism of CDPKs to salt stress is not well understood. In the current study, the wheat salt-responsive gene TaCDPK27 was identified. The open reading frame (ORF) of TaCDPK27 was 1875 bp, coding 624 amino acids. The predicted molecular weight and isoelectric point were 68.905 kDa and 5.6, respectively. TaCDPK27 has the closest relationship with subgroup III members of the CDPK family of rice. Increased expression of TaCDPK27 in wheat seedling roots and leaves was triggered by 150 mM NaCl treatment. TaCDPK27 was mainly located in the cytoplasm. After NaCl treatment, some of this protein was transferred to the membrane. The inhibitory effect of TaCDPK27 silencing on the growth of wheat seedlings was slight. After exposure to 150 mM NaCl for 6 days, the NaCl stress tolerance of TaCDPK27-silenced wheat seedlings was reduced, with shorter lengths of both roots and leaves compared with those of the control seedlings. Moreover, silencing of TaCDPK27 further promoted the generation of reactive oxygen species (ROS); reduced the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); aggravated the injury to photosystem II (PS II); and increased programmed cell death (PCD) in wheat leaves under NaCl treatment, confirming that the TaCDPK27-silenced seedlings exhibited more NaCl injury than control seedlings. Taken together, the decrease in NaCl tolerance in TaCDPK27-silenced seedlings was due to excessive ROS accumulation and subsequent aggravation of the NaCl-induced PCD. TaCDPK27 may be essential for positively regulating salt tolerance in wheat seedlings.

Metacaspases (MCAs), a family of caspase-like proteins, are important regulators of programmed cell death (PCD) in plant defense response. Autophagy is an important regulator of PCD. This study explored the underlying mechanism of the interaction among PCD, MCAs, and autophagy and their impact on wheat response to salt stress. In this study, the wheat salt-responsive gene

The hierarchical organization of building blocks is an important characteristic of self-assembly. Herein, we report a series of triangular hierarchical assemblies formed by C3-symmetric 5,10,15-triethyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole-2,7,12-tricarbaldehyde (M1) on the graphite surface. The molecule assembles into a hexagonal array on the graphite surface at room temperature with a trimeric assembly motif as the basic building block of the hierarchical assembly. With the increase of annealing temperature, the sizes of triangles in hierarchical assemblies vary from large to small with the presence of antiparallelly arranged molecular dimers as building blocks at the triangular boundaries. The hierarchical-order-level-dependent intermolecular interaction and molecule–substrate interaction were modeled, and the entropy contributions of alkyl substitution at different temperatures were proposed to account for the observed structural evolution process. This work provides a new example of hier...

The on-surface coupling reactions of terminal alkynes catalyzed by exogenous cupric ions on chemically inert highly oriented pyrolytic graphite (HOPG) surface have been investigated by scanning tunnelling microscopy. In the presence of exogenous cupric ions, diyne-linked nanostructures generated via homocoupling of terminal alkynes are the exclusive products, whereas no coupling reaction occurs for the terminal alkynes on the surface in the absence of the cupric ions, suggesting that exogenous cupric ions are efficient to catalyze the highly chemoselective on-surface reaction of terminal alkynes. The HOPG surface displays a template effect to the growth and alignment of the products on the surface. As a result, 2D arrays of diyne-linked zigzag polymers and 2D diyne-linked porous polymers are fabricated from ditopic monomer 3,6-diethynylcarbazole and tritopic monomer 1,3,5-tris-(4-ethynylphenyl) benzene, respectively. This synthetic strategy combining the high selectivity of cupric ion catalyst as well as the template effect of on-surface synthesis approach could be a general strategy to fabricate diyne-linked nanostructures and nanomaterials on solid surfaces.

The on-surface synthesis of single-layered covalent organic frameworks (sCOFs) has been investigated by employing a 3-fold symmetric monomer 1 carrying aldehyde groups and the ditopic diamine building block 2 on a highly oriented pyrolytic graphite surface. The self-assembly of molecule 1 is persistently observed at the stoichiometric ratio of the reactive groups. The growth of sCOF network is observed, however, only at the excess of diamine monomers. By investigating the growth process of the sCOF network, the role of excessive diamine monomers can be understood by two aspects. Increasing the molar ratio of diamine monomer provides the driving force for the structural transition from the monomer self-assembly to the formation of the sCOF network. On the other hand, the excess diamine monomers provide basic environment for the transimination reaction and promote the formation of highly ordered sCOFs. The present work provides molecular understanding of the role of transimination reaction in imine-based COF synthesis.

Correction for ‘Novel enzyme-functionalized covalent organic frameworks for the colorimetric sensing of glucose in body fluids and drinks’ by Jie-Yu Yue et al., Mater. Chem. Front., 2021, 5, 3859–3866, DOI: 10.1039/D1QM00314C.

We have studied the self-assembly structure of meso-diphenyltetrathia [22]-annulene [2,1,2,1] (DPTTA) on highly oriented pyrolytic graphite (HOPG), Au(111), and single-layer graphene (SLG) modified Au(111) substrates. High resolution scanning tunneling microscopy (STM) reveals that DPTTA molecules pack into one dimensionally ordered row structure on graphene and HOPG surfaces, while assemble into two dimensional close-packed structure on Au(111) surface. We ascribe this difference to the effect of the substrate. The addition of C60 molecules on these DPTTA modified substrates further reveals that the structural difference in DPTTA adlayer can affect its ability to form donor-acceptor (D-A) hierarchical structure with C60 molecules. The results provide an example of substrate effect in self-assemblies of functional molecules, which is significant for the design of molecular based devices.

The design and construction of stable porous networks featuring tunable cavities for selective guest inclusion remains a great challenge in construction of functional miniature devices. Herein we report on construction and guest inclusion of stable 2D porphyrin-based molecular square grids connected by imine bonds showing crystalline pattern with periodic square cavities. Diperylene diimides molecules can be decorated into the square pores of the porphyrin-based molecular template on HOPG surfaces. The periodicity control over the covalent molecular grid and thus that of guest molecules is demonstrated by changing the building block. The preparation of robust host–guest systems may facilitate the fabrication of molecular miniature devices with designable properties.

A bilayer covalent organic framework (COF) of TTF-based building blocks was obtained by imine reaction between tetrathiafulvalene tetraaldehyde (4ATTF) and p-phenylenediamine (PPDA). Direct evidence for the eclipsed stacking of bilayer structure via π-π interaction between TTF units is provided by high resolution scanning tunneling microscopy.

We combine chiral amplification and host–guest chemistry to demonstrate an approach to achieve a switchable chiral assembly. After the addition of the guest coronene, homochiral honeycomb patterns transform into host–guest sunflower structures, in which supramolecular chirality is modulated dramatically.

硫代硫酸硫转移酶参与植物体内的硫代谢、氰化物的清除以及活性氧的生成与清除，与植物抗病反应密切相关。小麦抗、感白粉病近等基因系材料在接种白粉菌后均诱导表达硫代硫酸硫转移酶基因 TaTST ，并在接种后0~48 h内呈现2次诱导峰值，分别与白粉菌初次接触识别和附着胞侵入、吸器形成时间相对应，也与2次氧突发时间对应。 TaTST 在感病材料上的诱导表达水平明显高于在抗病材料上，由此导致的活性氧过度清除可能是导致感病反应的原因之一。 TaTST 也参与抗病反应过程。利用病毒诱导的基因沉默技术(virus-induced gene silencing, VIGS)创造了 TaTST 基因沉默的抗病植株。尽管充分发病时间后沉默植株叶片上并未观察到肉眼可见的病斑，但侵染早期白粉菌成功侵入频率的增加和次级菌丝的有限伸长说明 TaTST 沉默植株抗病水平下降。 TaTST 沉默导致乳突致密度下降和H 2 O 2 在细胞内的扩散时间延迟。因此， TaTST 可能通过调节活性氧的积累和扩散、乳突的形成等小麦-白粉菌互作早期的寄主细胞反应而参与小麦对白粉菌的抗侵入过程。

We systematically studied the operation of coadsorber-induced surface chirality in a series of enantiomeric surface supramolecular assemblies. The correlation of chiral amplification degree with the proportion of enantiomeric interaction in the total intermolecular interaction is deduced.

The orthogonality between the Schiff base reaction and the boronic acid dehydration reaction is explored during the on-surface synthesis process., The orthogonality between the Schiff base reaction and the boronic acid dehydration reaction is explored during the on-surface synthesis process. By activating the above two reactions in one-step and employing asymmetrical substituted monomers and the 3-fold symmetric monomer 1,3,5-tris(4-aminophenyl)benzene (TAPB), highly ordered imine–boroxine hybrid single-layered covalent organic frameworks (sCOFs) have been successfully constructed on HOPG by a gas–solid interface reaction method and characterized by scanning tunnelling microscopy (STM). In particular, the reaction between the meta-substituted monomer and TAPB generates sCOFB with a windmill structure, which is the first sCOF with surface chirality so far reported. The demonstration of the one-step synthesis of multiple linkages to form sCOFs can further enlarge the sCOF family and expand the design routes for functional 2D organic nanomaterials.

On-surface synthesis has become a very promising bottom-up approach to obtain a functional surface with designable chemical structures. Dynamic covalent chemistry is an interesting reaction strategy to form thermodynamically controlled products utilizing the reversible covalent bond as linkage, which can be formed, broken, and reformed during the reaction and therefore provide an incidence of error-checking and self-healing. In this chapter, we focused on the surface-assisted synthesis of molecular nanostructures using dynamic covalent linkers. By proper tuning the on-surface dynamic covalent reaction processes, highly ordered covalent bond connected nanostructures can be obtained on surfaces.

A pair of isomeric imine-based covalent organic frameworks with non-aromatic linkage has been fabricated at the graphite surface, which extends the structural diversity of surface covalent organic frameworks.

With graphene-like topology and designable functional moieties, single-layered covalent organic frameworks (sCOFs) have attracted enormous interest for both fundamental research and application prospects. As the growth of sCOFs involves the assembly and reaction of precursors in a spatial defined manner, it is of great importance to understand the kinetics of sCOFs formation. Although several large families of sCOFs and bulk COF materials based on different coupling reactions have been reported, the synthesis of isomeric sCOFs by exchanging the coupling reaction moieties on precursors has been barely explored. Herein, a series of isomeric sCOFs based on Schiff-base reaction is designed to understand the effect of monomer structure on the growth kinetics of sCOFs. The distinctly different local packing motifs in the mixed assemblies for the two isomeric routes closely resemble to those in the assemblies of monomers, which affect the structural evolution process for highly ordered imine-linked sCOFs. In addition, surface diffusion of monomers and the molecule-substrate interaction, which is tunable by reaction temperature, also play an important role in structural evolutions. This study highlights the important roles of monomer structure and reaction temperature in the design and synthesis of covalent bond connected functional nanoporous networks.

Two-dimensional materials have drawn a wide variety of interest because of the excellent properties. Two-dimensional covalent organic frameworks (2D COFs) are a class of porous, crystalline organic materials, which are constructed from well-designed organic monomers via covalent bond linkages. The excellent porosity and crystallinity coupled with the brilliant 2D π-conjugated system and π-π stacking columns endow 2D COFs promising properties. With the predesignable topological structures and functionalized monomer units, 2D COFs can be constructed with the characteristics of lower mass density, highly ordered structures, larger surface area and tunable pore size and shapes. Various 2D COFs with versatile properties and specific functions can be also obtained by post-synthesizing, loading of guest molecules and ions, compositing with other carbon-based materials, etc. Additionally, oriented 2D COF monolayers and thin films are also prepared on the substrate surface. Based on the distinct ordered molecular structures and excellent properties, this review further discusses the extensively promising applications of 2D COFs in the fields of gas absorption and storage, catalysis, molecules delivery, energy capacitance and transform, electronics and optoelectronics.