ABSTRACT
Efficient and environment-friendly nanopesticide delivery systems are critical for the sustainable development of agriculture. In this study, a graphene oxide nanocomposite was developed for pesticide delivery and plant protection with pyraclostrobin as the model pesticide. First, graphene oxide-pyraclostrobin nanocomposite was prepared through fast adsorption of pyraclostrobin onto graphene oxide with a maximum loading of 87.04%. The as-prepared graphene oxide-pyraclostrobin nanocomposite exhibited high stability during two years of storage, suggesting its high potential in practical application. The graphene oxide-pyraclostrobin nanocomposite could achieve temperature (25 °C, 30 °C and 35 °C) and pH (5, 7 and 9) slow-release behavior, which overcomes the burst release of conventional pyraclostrobin formulation. Furthermore, graphene oxide-pyraclostrobin nanocomposite exhibited considerable antifungal activities against Fusarium graminearum and Sclerotinia sclerotiorum both in vitro and in vivo. The cotoxicity factor assay revealed that there was a synergistic interaction when graphene oxide and pyraclostrobin were combined at the ratio of 1:1 against the mycelial growth of Fusarium graminearum and Sclerotinia sclerotiorum with co-toxicity coefficient values exceeding 100 in vitro. The control efficacy of graphene oxide-pyraclostrobin nanocomposite was 71.35% and 62.32% against Fusarium graminearum and Sclerotinia sclerotiorum in greenhouse, respectively, which was higher than that of single graphene oxide and pyraclostrobin. In general, the present study provides a candidate nanoformulation for pathogenic fungal control in plants, and may also expand the application of graphene oxide materials in controlling plant fungal pathogens and sustainable agriculture.
ABSTRACT
BACKGROUND: 1,25(OH)2D3/vitamin D3 receptor (VD3/VDR) signaling pathway can inhibit the occurrence of breast cancer in many ways. We used vitamin D3 to interfere with Hyperplasia of mammary glands (HMG) model rats, and to explore the intervention effect of vitamin D3 on HMG. METHODS: We divided 42 female rats into six groups randomly: blank control group, hyperplasia model group, negative control group, and vitamin D3 (VD3) groups of low-dose (LVD, 5 µg/kg), medium-dose (MVD, 10 µg/kg), and high-dose (HVD, 20 µg/kg). We established HMG model in all groups except for the blank control group, then different dose of VD3 was intraperitoneal injected for VD3 groups and normal saline (NS) was given to the negative control group. After the experiment, the body weights, heights and diameters of nipples, and the thickness of the mammary gland of rats were measured. The serum content of sex hormone and VD3 were detected by enzyme-linked immunosorbent assay (ELISA). The tissues of mammary glands were analyzed by hematoxylin and eosin (HE) stain, and the expression of estrogen receptor α (ERα), progesterone receptor (PR), and VDR were detected by immunohistochemical (IHC) stain. Similarly, the total protein expression of ERα, PR, and VDR were measured by western blot. RESULTS: Compared with the hyperplasia group, rats in the VD3 groups displayed a marked decrease of the thickness of the mammary glands and the height and diameter of the nipples. The serum estrogen (E2), testosterone (T), luteinizing hormone (LH), and VD3 was markedly decreased in all VD3 groups (P<0.05). The IHC results showed that ERα and PR was decreased in all three VD3 groups; however, VDR was increased. Western blot demonstrated that both ERα and PR were reduced in VD3 groups, while the VDR level was significantly enhanced. Overall, the findings suggested that VD3 could be used in HMG treatment. CONCLUSIONS: Supplementation of VD3 could markedly decrease the mammary gland thickness, nipple diameter, and nipple height of rats, accompanied by the decrease of serum E2, T, and LH. Intervention with VD3 can lead to decreased expression of ERa and PR, in conjunction with the increase of VDR.
ABSTRACT
Plant pathogens constantly develop resistance to antimicrobial agents, and this poses great challenges to plant protection. Therefore, there is a pressing need to search for new antimicrobials. The combined use of antimicrobial agents with different antifungal mechanisms has been recognized as a promising approach to manage plant diseases. Graphene oxide (GO) is a newly emerging and highly promising antimicrobial agent against various plant pathogens in agricultural science. In this study, the inhibitory activity of GO combined with fungicides (Mancozeb, Cyproconazol and Difenoconazole) against Fusarium graminearum was investigated in vivo and in vitro. The results revealed that the combination of GO and fungicides has significant synergistic inhibitory effects on the mycelial growth, mycelial biomass and spore germination of F. graminearum relative to single fungicides. The magnitude of synergy was found to depend on the ratio of GO and fungicide in the composite. In field tests, GO-fungicides could significantly reduce the disease incidence and disease severity, exhibiting a significantly improved control efficacy on F. graminearum. The strong synergistic activity of GO with existing fungicides demonstrates the great application potential of GO in pest management.
ABSTRACT
Nanopesticides with controlled release can achieve more effective utilization of pesticides. Here, to enhance the adsorption of pesticides onto the target organisms, the formulation of pesticides with temperature-responsive release was proposed by combing graphene oxide (GO) and existing pyrethroid pesticides (cyhalothrin, bifenthrin and fenpropathrin). Pesticides were loaded onto GO nanosheets as a carrier via a simple physisorption process, and the GO-pesticide nanocomposites exhibited temperature-responsive release and excellent storage stability, which are of vital importance to the practical application. Furthermore, we assessed the bioactivity of the GO-pesticide nanocomposites against spider mites (Tetranychus urticae Koch) indoors and in the field. As a result, GO-pesticide nanocomposites had many folds higher bioactivity than individual pesticides, and could be adsorbed on the cuticle of T. urticae and surface of bean leaves with highly uniform dispersibility. The easy preparation and higher bioactivity of GO-pesticide nanocomposites indicate their promising application potential in pest control and green agriculture.
ABSTRACT
Chitosan (CS) stacking mats with excellent performance for adsorption of copper ions (Cu(II)) in wastewater were fabricated by alternating electrospinning/electrospraying. The hierarchical structure of the stacking membranes was designed by CS micro-hemispheres sandwiched between CS fibers. The CS stack membranes prepared by the electrospinning technology could effectively increase the specific surface area, and thus, facilitate the adsorption of copper ions. CS stacking membranes with three layers reached adsorption equilibrium within 60 min, and had a maximum absorbance of 276.2 mg/g. The absorbance performance was superior to most of the reported CS adsorbents. Compared with CS fiber mats which were dominated by CS chemical structure during adsorption, the stacking structure of CS membranes contributed to the high efficient capability, and exhibited the multilayer adsorption behavior. This study may develop a promising method for the design of environmentally-friendly natural polymer adsorbents to remove Cu(II) in wastewater.
ABSTRACT
Chitosan/cellulose acetate (CS/CA) used as a biopolymer systema, with the addition of TiO2 as photocatalyst (C-T/CA) were fabricated by alternating electrospinning/electrospraying technology. The uniform dispersion of TiO2 and its recovery after the removal of methyl orange (MO) was achieved by incorporating TiO2 in CS electrosprayed hemispheres. The effects of pH values, contact time, and the amount of TiO2 on adsorption and photocatalytic degradation for MO of the C-T/CA were investigated in detail. When TiO2 content was 3 wt %, the highest MO removal amount for fiber membranes (C-T-3/CA) reached 98% at pH value 4 and MO concentration of 40 mg/L. According to the data analysis, the pseudo-second-order kinetic and Freundlich isotherm model were well fitted to kinetic and equilibrium data of MO removal. Especially for C-T-3/CA, the fiber membrane exhibited multiple layers of adsorption. All these results indicated that adsorption caused by electrostatic interaction and photocatalytic degradation were involved in the MO removal process. This work provides a potential method for developing a novel photocatalyst with excellent catalytic activity, adsorbing capability and recycling use.
