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Mu L.,Agro Environmental Protection Institute | Gao Y.,Nankai University | Hu X.,Nankai University

Graphene oxide (GO) has been employed in various fields, and its ecological and health risks have attracted much attention. A small and inexpensive biomolecule, l-cysteine, was covalently immobilized onto GO to form l-cysteine-GO (CysGO) as a thio-functionalized nanosheet of 1.4nm in thickness. Both the d-spacing and crystallinity of CysGO were observed to be lower than those of GO, whereas the D and G peaks remained similar to those of GO. CysGO exhibited remarkable uptake invivo: no tissue defects, malformation, death or significant hatching delay were observed in zebrafish embryos. Significant DNA damage, decreased Na+/K+-ATPase activity and decreased mitochondrial membrane potential were not observed for CysGO. As a nonspecific activity linked to nanotoxicology, the unpaired electron spinning intensity of CysGO was approximately two orders of magnitude lower than that of GO. Oxygen microsensor analysis showed that the hypoxic and normoxic environments resulting from the presence of GO and CysGO envelopment, respectively, contributed to the difference in biocompatibility. CysGO also protected embryos from arsenic poisoning. Thus, CysGO has the advantageous properties of GO, exhibits excellent biocompatibility, acts as a breathable coating and antidote, and is suitable for various applications. © 2015 Elsevier Ltd. Source

Hu X.,Nankai University | Kang J.,Nankai University | Lu K.,Nankai University | Zhou R.,Nankai University | And 2 more authors.
Scientific Reports

Graphene oxide (GO) is widely used in various fields and is considered to be relatively biocompatible. Herein, "indirect" nanotoxicity is first defined as toxic amplification of toxicants or pollutants by nanomaterials. This work revealed that GO greatly amplifies the phytotoxicity of arsenic (As), a widespread contaminant, in wheat, for example, causing a decrease in biomass and root numbers and increasing oxidative stress, which are thought to be regulated by its metabolisms. Compared with As or GO alone, GO combined with As inhibited the metabolism of carbohydrates, enhanced amino acid and secondary metabolism and disrupted fatty acid metabolism and the urea cycle. GO also triggered damage to cellular structures and electrolyte leakage and enhanced the uptake of GO and As. Co-transport of GO-loading As and transformation of As(V) to high-toxicity As(III) by GO were observed. The generation of dimethylarsinate, produced from the detoxification of inorganic As, was inhibited by GO in plants. GO also regulated phosphate transporter gene expression and arsenate reductase activity to influence the uptake and transformation of As, respectively. Moreover, the above effects of GO were concentration dependent. Given the widespread exposure to As in agriculture, the indirect nanotoxicity of GO should be carefully considered in food safety. Source

Li H.,Shandong University | Liu J.,Shandong University | Liang X.,Agro Environmental Protection Institute | Hou W.,Shandong University | Tao X.,Shandong University
Journal of Materials Chemistry A

BiOBr lamellas were synthesized at different reaction pH values via a hydrothermal process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and N2 sorption measurements were used to characterize the BiOBr samples. BiOBr samples have the same lamella structures and band gaps but different lamella sizes and thicknesses. Adjusting the pH of the reaction system tunes the BiOBr lamella thickness from 42 to 21 nm. The photodegradation efficiencies of the BiOBr lamellas for rhodamine B (RhB) and methylene blue (MB) in aqueous solution were examined. The degradation efficiency for RhB is much higher than that for MB. The decrease in BiOBr lamella thickness significantly enhances the photocatalytic activity for dye degradation, despite the decrease in exposed photoactive (001) facet percentage. Decreasing the lamella thickness from 42 to 21 nm yields a more than fourfold enhancement in photodegradation efficiency of BiOBr samples for RhB. The most important factor influencing the photocatalytic activity of the BiOBr samples is their lamella thickness, rather than the exposed (001) facet percentage. Thus, even for flaky semiconductors with high exposed photoactive facet contents, the influence of lamella thickness on photocatalytic activity should be preferentially considered. This journal is © the Partner Organisations 2014. Source

Fourier transform infrared microscope and confocal Raman spectroscope were employed in this study to investigate four kinds of biodegradable plastics: poly(lactic acid),poly(butylenes adipate-co-terephthalate), poly(butylenes succinate) and poly(hydroxybutyrate-co-hydroxyvalerate), which are used more and more popularly in everyday life but can not be identified easily with other instruments. Infrared and Raman spectra of the plastics were tentatively interpreted. The indicative peaks to characterize the four polymers were also summarized. The result in this study can help the forensic scientists discriminate the plastics accurately when they occurred as trace evidences in cases, it also offers the producer and environment scientists an effective, non-invasive and fast method to characterize and identify these four polymers. © 2012 Springer Science+Business Media, LLC. Source

Sun S.,Nanjing Agricultural University | Gu M.,Nanjing Agricultural University | Cao Y.,Nanjing Agricultural University | Huang X.,Nanjing Agricultural University | And 5 more authors.
Plant Physiology

A number of phosphate (Pi) starvation- or mycorrhiza-regulated Pi transporters belonging to the Pht1 family have been functionally characterized in several plant species, whereas functions of the Pi transporters that are not regulated by changes in Pi supply are lacking. In this study, we show that rice (Oryza sativa) Pht1;1 (OsPT1), one of the 13 Pht1 Pi transporters in rice, was expressed abundantly and constitutively in various cell types of both roots and shoots. OsPT1 was able to complement the proton-coupled Pi transporter activities in a yeast mutant defective in Pi uptake. Transgenic plants of OsPT1 overexpression lines and RNA interference knockdown lines contained significantly higher and lower phosphorus concentrations, respectively, compared with the wild-type control in Pi-sufficient shoots. These responses of the transgenic plants to Pi supply were further confirmed by the changes in depolarization of root cell membrane potential, root hair occurrence, 33P uptake rate and transportation, as well as phosphorus accumulation in young leaves at Pi-sufficient levels. Furthermore, OsPT1 expression was strongly enhanced by the mutation of Phosphate Overaccumulator2 (OsPHO2) but not by Phosphate Starvation Response2, indicating that OsPT1 is involved in the OsPHO2-regulated Pi pathway. These results indicate that OsPT1 is a key member of the Pht1 family involved in Pi uptake and translocation in rice under Pi-replete conditions. © 2012 American Society of Plant Biologists. Source

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