A marine coating: Self-healing, stable release of Cu2+, anti-biofouling.

We developed a marine coating consisting of Cu-MOF-74, multi-walled carbon nanotube containing carboxyl groups (MWCNT-COOH) and self-healing polymers, which simultaneously possesses self-healing and anti-biofouling properties. Cu-MOF-74 can stably release Cu2+ by virtue of the coordination dissociative mechanism. Studies have proved that MWCNT can inhibit the growth of bacteria, so adding the MWCNT can help to reduce the amount of the copper ions and ensure the antibacterial effect of the coating. In addition, the cross-linked network and abundant -COOH provided by the polymers and MWCNT-COOH further prevent the loss of copper ions. Moreover, the coating we prepared has good performance of self-healing at room temperature or slightly heated because the polymers possess abundant non-covalent hydrogen bonds. Finally, the coating not only has superior antibacterial property, but also effectively prevents the adhesion of macrofouling organism. Therefore, the coating has a longer service life and its environmental friendliness has also been improved.

Self-Enhanced Antibacterial and Antifouling Behavior of Three-Dimensional Porous Cu2O Nanoparticles Functionalized by an Organic-Inorganic Hybrid Matrix.

Cu2O is currently an important protective material for domestic engineering and equipment used to exploit marine resources. Cu+ is considered to have more effective antibacterial and antifouling activities than Cu2+. However, disproportionation of Cu+ in the natural environment leads to its reduced bioavailability and weakened reactivity. Novel and functionalized Cu2O composites could enable efficient and environmentally friendly applications of Cu+. To this end, a series of three-dimensional porous Cu2O nanoparticles (3DNP-Cu2O) functionalized by organic (redox gel, R-Gel)-inorganic (reduced graphene oxide, rGO) hybrids─3DNP-Cu2O/rGOx@R-Gel─at room temperature by immobilization-reduction method was prepared and applied for protection against marine biofouling. 3DNP-Cu2O/rGO1.76@R-Gel includes rGO and R-Gel shape 3D porous Cu2O nanoparticles with diameters ∼177 nm and strong dispersion and antioxidant stability. Compared with commercial Cu2O (Cu2O-0), 3DNP-Cu2O/rGO1.76@R-Gel exhibited an ∼50% higher bactericidal rate, ∼96.22% higher water content, and ∼75% lower adhesion of mussels and barnacles. Moreover, 3DNP-Cu2O/rGOx@R-Gel maintains the same excellent, stable, and long-lasting bactericidal performance as Cu2O-0@R-Gel while reducing the average copper ion release concentration by ∼56 to 76%. This was also confirmed by X-ray diffraction, X-ray photoelectric spectroscopy (XPS), atomic absorption spectroscopy, and antifouling tests. In addition, XPS tests of rGO-Cu2+ and R-Gel-Cu2+, photocurrent tests of 3DNP-Cu2O/rGO1.76@R-Gel, and energy-dispersive spectrometry pictures of bacteria confirm that R-Gel and rGO act as electron donors and transfer substrates driving the reduction of Cu2+ (Cu2+ → Cu+) and the diffusion of Cu+. Thus, a self-growing antibacterial and antifouling system of 3DNP-Cu2O/rGO1.76@R-Gel was achieved. The mechanism of accelerated bacterial inactivation and resistance to mussel and barnacle adhesion by 3DNP-Cu2O/rGO1.76@R-Gel was interpreted. It is shown that rGO and R-Gel are important players in the antibacterial and antifouling system of 3DNP-Cu2O/rGO1.76@R-Gel.

Dynamic QTL mapping revealed primarily the genetic structure of photosynthetic traits in castor (Ricinus communis L.).

High photosynthetic efficiency is the basis of high biomass and high harvest index in castor (Ricinus communis L.). Understanding the genetic law of photosynthetic traits will facilitate the breeding for high photosynthetic efficiency. In this study, the dynamic QTL mapping was performed with the populations F2 and BC1 derived from 2 parents with significant difference in net photosynthetic rate (Pn) at 3 stages, in order to reveal the genetic structure of photosynthetic traits. In F2 population, 26 single-locus QTLs were identified, including 3/3/1 (the QTL number at stage I/II/III, the same below), 1/2/0, 1/2/2, 1/3/1, 0/1/1, and 1/1/2 QTLs conferring Pn, water use efficiency (Wue), transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and chlorophyll content (Cc), with a phenotypic variation explained (PVE) of 8.40%/8.91%/6.17%, 5.36%/31.74%/0, 7.31%/12.80%/15.15%, 1.60%/6.44%/0.02%, 0/1.10%/0.70% and 2.77%/3.96%/6.50% respectively. And 53 epistatic QTLs (31 pairs) were identified, including 2/2/5, 5/6/3, 4/4/2, 6/3/2, 3/2/0 and 4/0/0 ones conferring the above 6 traits, with a PVE of 6.52%/6.47%/19.04%, 16.72%/15.67%/14.12%, 18.57%/15.58%/7.34%, 21.72%/8.52%/7.13%, 13.33%/4.94%/0 and 7.84%/0/0 respectively. The QTL mapping results in BC1 population were consistent with those in F2 population, except fewer QTLs detected. Most QTLs identified were minor-effect ones, only a few were main-effect ones (PVE > 10%), focused on 2 traits, Wue and Tr, such as qWue1.1, qWue1.2, FqTr1.1, FqTr6, BqWue1.1 and BqTr3; The epistatic effects, especially those related to the dominance effects were the main genetic component of photosynthetic traits, and all the epistatic QTLs had no single-locus effects except qPn1.2, FqGs1.2, FqCi1.2 and qCc3.2; The detected QTLs underlying each trait varied at different stages except stable QTLs qGs1.1, detected at 3 stages, qWue2, qTr1.2 and qCc3.2, detected at 2 stages; 6 co-located QTLs were identified, each of which conferring 2-5 different traits, demonstrated the gene pleiotropy between photosynthetic traits; 2 QTL clusters, located within the marker intervals RCM1842-RCM1335 and RCM523-RCM83, contained 15/5 (F2/BC1) and 4/4 (F2/BC1) QTLs conferring multiple traits, including co-located QTLs and main-effect QTLs. The above results provided new insights into the genetic structure of photosynthetic traits and important references for the high photosynthetic efficiency breeding in castor plant.

Regulation of PIN-FORMED Protein Degradation.

Auxin action largely depends on the establishment of auxin concentration gradient within plant organs, where PIN-formed (PIN) auxin transporter-mediated directional auxin movement plays an important role. Accumulating studies have revealed the need of polar plasma membrane (PM) localization of PIN proteins as well as regulation of PIN polarity in response to developmental cues and environmental stimuli, amongst which a typical example is regulation of PIN phosphorylation by AGCVIII protein kinases and type A regulatory subunits of PP2A phosphatases. Recent findings, however, highlight the importance of PIN degradation in reestablishing auxin gradient. Although the underlying mechanism is poorly understood, these findings provide a novel aspect to broaden the current knowledge on regulation of polar auxin transport. In this review, we summarize the current understanding on controlling PIN degradation by endosome-mediated vacuolar targeting, autophagy, ubiquitin modification and the related E3 ubiquitin ligases, cytoskeletons, plant hormones, environmental stimuli, and other regulators, and discuss the possible mechanisms according to recent studies.

GhROP6 GTPase modulates auxin accumulation in cotton fibers by regulating cell-specific GhPIN3a localization.

PIN-FORMED- (PIN) mediated polar auxin transport plays a predominant role in most auxin-triggered organogenesis in plants. Global control of PIN polarity at the plasma membrane contributes to the essential establishment of auxin maxima in most multicellular tissues. However, establishment of auxin maxima in single cells is poorly understood. Cotton fibers, derived from ovule epidermal cells by auxin-triggered cell protrusion, provide an ideal model to explore the underlying mechanism. Here, we report that cell-specific degradation of GhPIN3a, which guides the establishment of the auxin gradient in cotton ovule epidermal cells, is associated with the preferential expression of GhROP6 GTPase in fiber cells. In turn, GhROP6 reduces GhPIN3a abundance at the plasma membrane and facilitates intracellular proteolysis of GhPIN3a. Overexpression and activation of GhROP6 promote cell elongation, resulting in a substantial improvement in cotton fiber length.

An Unexpected Regulatory Sequence from Rho-Related GTPase6 Confers Fiber-Specific Expression in Upland Cotton.

Cotton fibers, single seed trichomes derived from ovule epidermal cells, are the major source of global textile fibers. Fiber-specific promoters are desirable to study gene function and to modify fiber properties during fiber development. Here, we revealed that Rho-related GTPase6 (GhROP6) was expressed preferentially in developing fibers. A 1240 bp regulatory region of GhROP6, which contains a short upstream regulatory sequence, the first exon, and the partial first intron, was unexpectedly isolated and introduced into transgenic cotton for analyzing promoter activity. The promoter of GhROP6 (proChROP6) conferred a specific expression in ovule surface, but not in the other floral organs and vegetative tissues. Reverse transcription PCR analysis indicated that proGhROP6 directed full-length transcription of the fused ß-glucuronidase (GUS) gene. Further investigation of GUS staining showed that proChROP6 regulated gene expression in fibers and ovule epidermis from fiber initiation to cell elongation stages. The preferential activity was enriched in fiber cells after anthesis and reached to peak on flowering days. By comparison, proGhROP6 was a mild promoter with approximately one-twenty-fifth of the strength of the constitutive promoter CaMV35S. The promoter responded to high-dosage treatments of auxin, gibberellin and salicylic acid and slightly reduced GUS activity under the in vitro treatment. Collectively, our data suggest that the GhROP6 promoter has excellent activity in initiating fibers and has potential for bioengineering of cotton fibers.

Water- and Acid-Sensitive Cu2O@Cu-MOF Nano Sustained-Release Capsules with Superior Antifouling Behaviors.

Marine biofouling is one of the technical bottlenecks restricting the development of the global marine economy. Among the commercial self-polishing antifouling coatings, cuprous oxide is an irreplaceable component because of its efficiency and broad-spectrum antibacterial activity. However, one of the biggest obstacles to achieving long-term antifouling is the "initial burst and final decay" of cuprous oxide in the coating. Here, we lock the copper ions by establishing an antifouling unit composed of Cu2O (core) and Cu-based metal-organic framework (Cu-MOF, shell). Cu-MOF is densely grown in situ on the periphery of Cu2O by acid proton etching. The shell structure of Cu-MOF can effectively improve the stability of the internal Cu2O and thus achieve the stable and slow release of copper ions. Furthermore, Cu2O@Cu-MOF nanocapsules can also achieve active defense by rapid and complete dissolution of Cu2O@Cu-MOF at local acidic microenvironment (pH ≤ 5) where the adhesion of fouling organisms occurs. Super-resolution fluorescence microscopy is used to explain the sterilization mechanism. Relying on the water- and acid-sensitive properties of Cu-MOF shell, the stable, controlled and efficient release of copper ions has been achieved for the Cu2O@Cu-MOF nanocapsules in the self-polishing antifouling coatings. Thus, these controlled-release nanocapsules make long-term antifouling promising.

Microporous Metal-Organic Framework Stabilized by Balanced Multiple Host-Couteranion Hydrogen-Bonding Interactions for High-Density CO2 Capture at Ambient Conditions.

Microporous metal organic frameworks (MOFs) show promising application in several fields, but they often suffer from the weak robustness and stability after the removal of guest molecules. Here, three isostructural cationic metal-organic frameworks {[(Cu4Cl)(cpt)4(H2O)4]·3X·4DMAc·CH3OH·5H2O} (FJU-14, X = NO3, ClO4, BF4; DMAc = N,N'-dimethylacetamide) containing two types of polyhedral nanocages, one octahedron, and another tetrahedron have been synthesized from bifunctional organic ligands 4-(4H-1,2,4-triazol-4-yl) benzoic acid (Hcpt) and various copper salts. The series of MOFs FJU-14 are demonstrated as the first examples of the isostructural MOFs whose robustness, thermal stability, and CO2 capacity can be greatly improved via rational modulation of counteranions in the tetrahedral cages. The activated FJU-14-BF4-a containing BF4(-) anion can take CO2 of 95.8 cm(3) cm(-3) at ambient conditions with an adsorption enthalpy only of 18.8 kJ mol(-1). The trapped CO2 density of 0.955 g cm(-3) is the highest value among the reported MOFs. Dynamic fixed bed breakthrough experiments indicate that the separation of CO2/N2 mixture gases through a column packed with FJU-14-BF4-a solid can be efficiently achieved. The improved robustness and thermal stability for FJU-14-BF4-a can be attributed to the balanced multiple hydrogen-bonding interactions (MHBIs) between the BF4(-) counteranion and the cationic skeleton, while the high-density and low-enthalpy CO2 capture on FJU-14-BF4-a can be assigned to the multiple-point interactions between the adsorbate molecules and the framework as well as with its counteranions, as proved by single-crystal structures of the guest-free and CO2-loaded FJU-14-BF4-a samples.

High anhydrous proton conductivity of imidazole-loaded mesoporous polyimides over a wide range from subzero to moderate temperature.

On-board fuel cell technology requires proton conducting materials with high conductivity not only at intermediate temperatures for work but also at room temperature and even at subzero temperature for startup when exposed to the colder climate. To develop such materials is still challenging because many promising candidates for the proton transport on the basis of extended microstructures of water molecules suffer from significant damage by heat at temperatures above 80 °C or by freeze below -5 °C. Here we show imidazole loaded tetrahedral polyimides with mesopores and good stability (Im@Td-PNDI 1 and Im@Td-PPI 2) exhibiting a high anhydrous proton conductivity over a wide temperature range from -40 to 90 °C. Among all anhydrous proton conductors, the conductivity of 2 is the highest at temperatures below 40 °C and comparable with the best materials, His@[Al(OH)(1,4-ndc)]n and [Zn3(H2PO4)6(H2O)3](Hbim), above 40 °C.