A rhoptry protein, localizing in the bulb region of rhoptries, could induce protective immunity against Eimeria tenella infection.

Background: Rhoptry organelle proteins (ROPs) secreted by apicomplexan parasites play important roles during parasites invasion and survival in host cells, and are potential vaccine candidates against apicomplexan diseases. Eimeria tenella (E. tenella) is one of the most noteworthy apicomplexan species, which causes hemorrhagic pathologies. Although dozens of putative E. tenella ROP sequences are annotated, most ROP proteins are not well studied. Methods: In this study, an E. tenella ROP21 gene was identified and the recombinant EtROP21 protein (rEtROP21) was expressed in Escherichia coli. The developmental expression levels, localization, and protective efficacy against E. tenella infection in chickens were studied. Results: An EtROP21 gene fragment with an open reading frame (ORF) of 981 bp was obtained from the Beijing strain of E. tenella. The rEtROP21 has a molecular weight of approximately 50 kDa and was recognized by rEtROP21-immunized mouse serum. Two specific protein bands, about 43 KDa and 95 KDa in size, were detected in the whole sporozoite proteins using the rEtROP21-immunized chicken serum. RT-qPCR analysis of the E. tenella ROP21 gene (EtROP21) revealed that its mRNA levels were higher in merozoites and sporozoites than in sporulated and unsporulated oocysts. Immunofluorescence and immunoelectron analyses showed that the EtROP21 protein predominantly localizes in the bulb region of rhoptries distributed at anterior, posterior, and perinuclear regions of E. tenella sporozoites. Immunization and challenge experiments revealed that immunizing chickens with rEtROP21 significantly increased their average body weight gain while decreasing mean lesion score and oocyst output (P <0.05). When compared with the challenged control group, the rEtROP21-immunized group was associated with a significantly higher relative weight gain (90.2%) and a greater reduction in oocyst output (67%) (P <0.05). The anticoccidial index of the rEtROP21-immunized group was 163.2. Chicken serum ELISA revealed that the levels of the specific anti- rEtROP21 antibody, IFN-γ, and IL-4 were significantly higher in the rEtROP21-immunized group than in the challenged control group (P <0.05). Conclusion: These results indicate that rEtROP21 can induce a high level of specific immune response and it is a potential candidate for the development of vaccines against E. tenella infection in chickens.

Phase transition and ionic conduction enhancement induced by co-doping of LiI and MnI2 in a one-dimensional lead iodide perovskite.

Herein, we demonstrated the unique advantage of a mechanochemical reaction to prepare a salt with hard and soft acid and base ions concurrently by solution synthesis owing to the soft acid preferring to combine with the soft base and vice versa. We prepared Bu4N1-xLixMnxPb1-xI3 (x = 0.011-0.14) by mechanochemical synthesis. The doping induced a structural phase transition at ∼342 K and much enhancement of ionic conduction above 342 K for all co-doped hybrids regarding Bu4NPbI3 because of the voids around the Mn2+/Li+ ions by doping.

MOF-Polymer Mixed Matrix Membranes as Chemical Protective Layers for Solid-Phase Detoxification of Toxic Organophosphates.

Zirconium-based metal-organic frameworks (Zr-MOFs) have been demonstrated as potent catalysts for the hydrolytic detoxification of organophosphorus nerve agents and their simulants. However, the practical implementation of these Zr-MOFs is limited by the poor processability of their powdered form and the necessity of water media buffered by a volatile liquid base in the catalytic reaction. Herein, we demonstrate the efficient solid-state hydrolysis of a nerve agent simulant (dimethyl-4-nitrophenyl phosphate, DMNP) catalyzed by Zr-MOF-based mixed matrix membranes. The mixed matrix membranes were fabricated by incorporating MOF-808 into the blending matrix of poly(vinylidene fluoride) (PVDF), poly(vinylpyrrolidone) (PVP), and imidazole (Im), in which MOF-808 provides highly active catalytic sites, the hydrophilic PVP helps to retain water for promoting the hydrolytic reaction, and Im serves as a base for catalytic site regeneration. Impressively, the mixed matrix membranes displayed excellent catalytic performance for the solid-state hydrolysis of DMNP under high humidity, representing a significant step toward the practical application of Zr-MOFs in chemical protective layers against nerve agents.

Metal-Organic Framework-Derived N-Doped Porous Carbon for a Superprotonic Conductor at above 100 °C.

The development of proton conductors capable of working at above 100 °C is of great significance for proton exchange membrane electrolysis cells (PEMECs) and proton exchange membrane fuel cells (PEMFCs) but remains to be an enormous challenge to date. In this work, we demonstrate for the first time that the N-doped porous carbon derived from metal-organic frameworks (MOFs) with great superiority can be exploited for high-performing proton conductors at above 100 °C. Through the pyrolysis of ZIF-8, the N-doped porous carbon (ZIF-8-C) featuring high chemical resistance to Fenton's reagent was readily prepared and then served as a robust host to accommodate H3PO4 molecules for proton transport. Upon impregnation with H3PO4, the resulting PA@ZIF-8-C exhibits low water swelling and high proton conduction of over 10-2 S cm-1 at a temperature above 100 °C, which is superior to many reported proton conductors. This work provides a new approach for the design of high-performing proton conductors at above 100 °C.

Acidic Groups Functionalized Carbon Dots Capping Channels of a Proton Conductive Metal-Organic Framework by Coordination Bonds to Improve the Water-Retention Capacity and Boost Proton Conduction.

Crystalline porous materials, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been demonstrated to be versatile material platforms for the development of solid proton conductors. However, most crystalline porous proton conductors suffer from decreasing proton conductivity with increasing temperature due to releasing water molecules, and this disadvantage severely restricts their practical application in electrochemical devices. In this work, for the first time, hydrophilic carbon dots (CDs) were utilized to hybridize with high proton conductivity MOF-802, which is a model of MOF proton conductors, aiming to improve its water-retention capacity and thus enhance proton conduction. The resultant CDs@MOF-802 exhibits impregnable proton conduction with increasing temperature, and the proton conductivity reaches 10-1 S cm-1, much superior to that of MOF-802, making CDs@MOF-802 one of the most efficient MOF proton conductors reported so far. This study provides a new strategy to improve the water-retention capacity of porous proton conductors and further realize excellent proton conduction.

Efficiently Boosting Moisture Retention Capacity of Porous Superprotonic Conducting MOF-802 at Ambient Humidity via Forming a Hydrogel Composite Strategy.

Metal-organic frameworks (MOFs) provided a versatile platform for the development of new solid protonic electrolytes but faced great challenges regarding their low chemical stability and poor moisture retention capacity. Herein, we presented the proton-conducting study for zirconium-based MOF-802, revealing that MOF-802 possessed excellent features of extra aqueous and acidic stabilities and room-temperature superprotonic conduction with a proton conductivity of 1.05 × 10-2 S cm-1 at 288 K under 98% relative humidity (RH). Unfortunately, due to the liberation of water molecules from pores/channels, the proton conductivity of MOF-802 dropped significantly at the temperature above 318 K. To solve this issue, for the first time, MOF-802 was hybridized with poly(vinyl alcohol) (PVA) to form MOF-802@PVA hydrogel composites, where the moisture retention capacity of MOF-802 was greatly improved, giving the high room-temperature proton conductivity over 10-3 S cm-1 under ambient humidity. This work paves a new way to improve the moisture retention capacity and proton-conducting performances of porous proton conductors.