Infantile Internal and External Exposure to Neonicotinoid Insecticides: A Comparison of Levels across Various Sources.

Little is known about exposure of infants to neonicotinoid insecticides (NEOs). In this study, concentrations of six parent NEOs (p-NEOs) and N-desmethyl-acetamiprid (N-dm-ACE) were measured in urine and whole blood samples from infants, in addition to breast milk, infant formula, and tap water collected in South China. The p-NEO with the highest median concentration in urine (0.25 ng/mL) and blood (1.30) samples was dinotefuran (DIN), while imidacloprid (IMI) was abundant in breast milk (median: 0.27 ng/mL), infant formula (0.22), and tap water (0.028). The older infants (181-360 days) might face higher NEO and N-dm-ACE exposure than younger infants (0-180 days). Blood samples contained a significantly (p < 0.01) higher median concentration of ∑6p-NEOs (2.03 ng/mL) than that of urine samples (0.41), similar to acetamiprid (ACE), IMI, thiacloprid (THD), DIN, and N-dm-ACE, suggesting that NEOs readily partition into blood. Furthermore, breast-fed infants tend to have higher exposure levels than formula-fed infants. Infant formula prepared with tap water augmented the daily intake of ∑NEOs. The external sources contributed 80% of the total dose to IMI and clothianidin (CLO) exposure, while other unknown sources contributed to ACE, THD, and DIN exposure in infants. To the best of our knowledge, this is the first study to assess levels and sources of infantile exposure to NEOs through internal and external exposure assessment.

Neonicotinoid Insecticides and Their Metabolites Can Pass through the Human Placenta Unimpeded.

Studies on neonicotinoid (NEO) exposure in pregnant women and fetuses are scarce, and transplacental transfer of these insecticides is unknown. In this study, parent NEOs (p-NEOs) and their metabolites (m-NEOs) were determined in 95 paired maternal (MS) and cord serum (CS) samples collected in southern China. Imidacloprid was the predominant p-NEO in both CS and MS samples, found at median concentrations of 1.84 and 0.79 ng/mL, respectively, whereas N-desmethyl-acetamiprid was the most abundant m-NEO in CS (median: 0.083 ng/mL) and MS (0.13 ng/mL). The median transplacental transfer efficiencies (TTEs) of p-NEOs and m-NEOs were high, ranging from 0.81 (thiamethoxam, THM) to 1.61 (olefin-imidacloprid, of-IMI), indicating efficient placental transfer of these insecticides. Moreover, transplacental transport of NEOs appears to be passive and structure-dependent: cyanoamidine NEOs such as acetamiprid and thiacloprid had higher TTE values than the nitroguanidine NEOs, namely, clothianidin and THM. Multilinear regression analysis revealed that the concentrations of several NEOs in MS were associated significantly with hematological parameters related to hepatotoxicity and renal toxicity. To our knowledge, this is the first analysis of the occurrence and distribution of NEOs in paired maternal-fetal serum samples.

Antibacterial properties and mechanism of selenium nanoparticles synthesized by Providencia sp. DCX.

Selenium nanoparticles (SeNPs) have attracted great interest as a potential antimicrobial agent. However, there is limited research on the antibacterial activity and possible mechanisms of biosynthesized SeNPs. In this study, spherical bio-SeNPs with an average size of 120 nm were synthesized by strain Providencia sp. DCX. The SeNPs were further applied to investigate the antibacterial properties of model bacteria, including Gram-positive (Staphylococcus aureus, Bacillus cereus and Bacillus subtilis) and Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Vibrio parahemolyticus). The biosynthesized SeNPs demonstrated strong inhibition activity against the growth of these pathogens. When treated with 500 mg/L SeNPs, most of the tested bacteria were destructed within 12 h, among which the mortality rates of Gram-negative bacteria were much better. The leakage tests illustrated that there existed more proteins and polysaccharides outside the cells after reacted with bio-SeNPs. It was indicated that the leakages of proteins and polysaccharides were caused by permeability changes of membranes and the disruption of cell walls. And the change of reactive oxygen species (ROS) intensity indicated that oxidative damage may play the significant role in the antibacterial processes. The results showed that several bacteria could be effectively inhibited and destructed, suggesting the potential of using the biosynthesized SeNPs as antibacterial agents for bacterial infectious diseases.

Interaction of graphene-family nanomaterials with microbial communities in sequential batch reactors revealed by high-throughput sequencing.

The accelerated development and application of graphene-family nanomaterials (GFNs) have increased their release to various environments and converged in wastewater treatment plants (WWTPs). However, little is known about the interactions between GFNs and microbes in WWTPs. In this study, the interaction of graphene oxide (GO) or graphene (G) at different concentrations with microbial communities in sequential batch reactors was investigated. Transmission electron microscopy and Raman spectroscopy analyses showed that the structures of GFNs were obviously changed, which suggested GFNs could be degraded by some microbes. Significantly higher DNA concentration and lower cell number in high-concentration GO group were detected by DNA leakage test and qPCR analysis, which confirmed the microbial toxicity of GO. The chemical oxygen demand and ammonia nitrogen removals were significantly affected by G and GO with high concentrations. Further, high-throughput sequencing confirmed the composition and dynamic changes of microbial communities under GFNs exposure. Saccharibacteria genera incertae sedis (12.55-28.05%) and Nakamurella (20.45-29.30%) were the predominant genera at two stages, respectively. FAPROTAX suggested 12 functional groups with obvious changes related to the biogeochemical cycle of C, N and S. Molecular ecological network analysis showed that the networks were more complex in the presence of GFNs, and the increased negative interactions reflected more competition relationships in microbial communities. This study is the first to report the effect of GFNs on network of microbial communities, which provides in-depth insights into the complex and highlights concerns regarding the risk of GFNs to WWTPs.

Colorimetric detection of Hg2+ using gold nanoparticles synthesized by Trichosporon montevideense WIN.

OBJECTIVE: To investigate a simple, cost-effective and eco-friendly method for colorimetric detection of Hg2+ using gold nanoparticles (AuNPs) synthesized by Trichosporon montevideense WIN. RESULTS: Hg2+ induced more visible blue shift of SPR band of the AuNPs than other heavy metal ions including Pb2+, Cd2+, Fe3+, Mn2+, Co2+ and Cu2+. The λmax of SPR band exhibited a gradual blue shift from 548 to 537 nm with concentration of Hg2+ increasing (0-200 µM), and the absorbance ratio (A537/A548) showed a positive linear correlation with Hg2+ concentration (R2 = 0.96). AuNPs synthesized at pH 6 showed more obvious blue shift than at pH 5 and pH 7. Through Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) analysis, biomolecules coated on the AuNPs were speculated to dominate the formation of a core (Au)-shell (Hg) structure, which resulted in the colorimetric response. CONCLUSION: A sensitive and selective approach to detect Hg2+ using AuNPs synthesized by Trichosporon montevideense WIN is reported for the first time, which can provide a new potential candidate for detecting Hg2+ in the future.

Rod-shaped gold nanoparticles biosynthesized using Pb2+-induced fungus Aspergillus sp. WL-Au.

Gold nanoparticles (AuNPs) attracted much attention owing to their distinguished characteristics and applications. In this study, rod-shaped AuNPs were biosynthesized using Pb2+-induced fungus Aspergillus sp. The synthesized AuNPs showed a UV-vis absorption peak at 534 nm. Scanning electron microscopy and transmission electron microscopy analyses showed that rod-shaped AuNPs were biosynthesized and attached on the mycelia surfaces. Energy-dispersive spectrometer analysis identified gold as the unique metallic composition of synthesized nanoparticles. X-ray powder diffraction analysis showed that the AuNPs were face-centered cubic crystalline structure. Furthermore, Fourier transform infrared spectroscopy analysis detected functional groups, including C = O, C-O-C, amine I and II which played active roles in AuNPs formation. In addition, the main shape of synthesized AuNPs changed from sphere to rod-shape with the increase of biomass and Pb2+ concentration. This study reports quite uniform rod-shaped AuNPs biosynthesized using Pb2+-induced fungus Aspergillus sp. WL-Au for the first time. This will provide a valid alternative for oriented biosynthesis of AuNPs.

Exposure to nitrogenous based flame retardants in Chinese population: Evidence from a national-scale study.

Extensive use of nitrogen-based flame retardants (NFRs) has resulted in their widespread environmental occurrence. To investigate human exposure to NFRs on a national scale, the abundance and spatial distribution of NFRs were assessed in urine specimens collected from 13 cities in China. Six out of eight target NFRs were detectable in more than half of the urine samples, and the total concentrations of NFRs ranged from 3.22 to 880 ng/mL with a median of 46.7 ng/mL. Cyanuric acid was the most abundant chemical, accounting for 66.2%, followed by melamine (16.3%), ammelide (10.8%), and ammeline (6.11%). Regional differences in concentrations and composition profiles of NFRs were observed within China as a result of different production and application profiles. In addition, we found that urinary NFRs levels were much higher than but statistically correlated with that of organophosphates (r2 = 0.69, p < 0.05), another class of phosphorus-based flame retardant, implying similar emission sources and/or human exposure pathways. Furthermore, the estimated daily intakes and hazard quotients revealed that the Chinese population's exposure to NFRs is within safe limits. To the best of our knowledge, this is the first study to document the ubiquitous occurrence and region-specific variations of human exposure to NFRs in China.

Placental transfer of bisphenol diglycidyl ethers (BDGEs) and its association with maternal health in a population in South of China.

Despite high production and usage, little is known about exposure to bisphenol diglycidyl ethers (BDGEs) and their derivatives in pregnant women and fetuses. In this study, we determined nine BDGEs in 106 paired maternal and cord serum samples collected from e-waste dismantling sites in South of China. Bisphenol A bis (2,3-dihydroxypropyl) glycidyl ether (BADGE·2H2O), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether (BADGE·HCl·H2O), and bisphenol F diglycidyl ether (BFDGE) were the major BDGEs, with median concentrations of 0.57, 4.07, and 1.60 ng/mL, respectively, in maternal serum, and of 3.58, 5.61, and 0.61 ng/mL, respectively, in cord serum. The transplacental transfer efficiencies (TTEs) were estimated for BDGEs found in samples, and median values were in the range of 0.98 (BFDGE) to 5.91 (BADGE·2H2O). Our results suggested that passive diffusion plays a role in the placental transfer of BADGE·HCl·H2O and BFDGE, whereas several mechanisms contribute to the high accumulation of BADGE·2H2O in cord serum. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of BDGEs and blood clinical biomarkers, especially those related to liver injuries, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and adenosine deaminase (ADA) (P < 0.05). To our knowledge, this is the first study to report the occurrence of BDGEs in paired maternal-fetal serum samples and provide new insights into prenatal and fetal exposures. The newly discovered TTEs in maternal-fetal pairs contribute to a fuller inventory of the transmission activity of pollutants in the human body, ultimately adding to a more significant comprehensive risk evaluation.

[Characteristics of selenium nanoparticles synthesized by cell-free supernatant Cupriavidus sp. SHE].

In recent years, selenium nanoparticles (SeNPs) have been widely used in many fields such as nanotechnology, biomedicine and environmental remediation due to their good electrical conductivity, photothermal properties and anticancer properties. In this study, the cell-free supernatant, whole cell and the cell-free extracts of the strain Cupriavidus sp. SHE were used to synthesize SeNPs, and several methods were applied to analyze the crystal structure and surface functional groups of the nanoparticles. Finally, Pseudomonas sp. PI1 (G⁺) and Escherichia coli BL21 (G⁻) were selected to investigate the antibacterial properties of SeNPs. Cell-free supernatant, whole cell and cell-free extracts of the strain could synthesize SeNPs. As for the cell-free supernatant, selenite concentration of 5 mmol/L and pH=7 were favorable for the synthesis of SeNPs. TEM images show that the average size of nanospheres synthesized by the supernatant was 196 nm. XRD analysis indicates the hexagonal crystals structure of SeNPs. FTIR and SDS-PAGE confirmed the proteins bound to the surfaces of SeNPs. SeNPs synthesized by cell-free supernatant showed no antimicrobial activities against Pseudomonas sp. PI1 and Escherichia coli BL21 (DE3). These results suggest that proteins played an important role in biotransformation of SeNPs in an eco-friendly process, and SeNPs synthesized in this study were non-toxic and biologically compatible, which might be applied in other fields in the future.

Bacteria mediated Fenton-like reaction drives the biotransformation of carbon nanomaterials.

Carbon nanomaterials (CNs), which gain heightened attention as novel materials, are increasingly incorporated into daily products and thus are released into the environment. Limited research on CNs environmental fates lags their industry growth, only few bacteria have been confirmed to biotransform CNs and the mechanism behind has not been revealed yet. In this study, four types of commercial CNs, i.e. graphene oxide (GO), reduced graphene oxide (RGO), single walled carbon nanotubes (SWCNTs), and oxidized (carboxylated) SWCNTs, were selected for investigation. The biotransformation of CNs by Labrys sp. WJW, which could grow with these CNs as the sole carbon source, was investigated. The bacterial transformation was proved by qPCR, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, liquid chromatography/time-of-flight/mass spectrometry, and gas chromatograph-mass spectrometry analyses. The biotransformation resulted in morphology change, defect increase and functional group change of these CNs. Furthermore, the underlying mechanism of CNs biodegradation mediated by extracellular Fenton-like reaction was demonstrated. In this reaction, the OH production was mediated by reduction of H2O2 involved a continuous cycle of Fe(II)/Fe(III). These findings reveal a novel degradation mechanism of microorganism towards high molecular weight substrate, which will provide a new insight into the environmental fate of CNs and the guidance for their safer use.

Characterization of biogenic selenium nanoparticles derived from cell-free extracts of a novel yeast Magnusiomyces ingens.

A facile one-pot and effective green process for biogenic selenium nanoparticles (SeNPs) was obtained using the cell-free extracts of a novel yeast Magnusiomyces ingens LH-F1. The corresponding absorption peak of SeNPs was observed at ~ 560 nm by UV-vis spectrophotometer. In the present study, SeO2 2 mM, protein 500 mg L-1 and pH 7 were preferable to the biosynthesis of SeNPs. The effects of pH, SeO2 concentration and protein concentration on the synthesis process were different. Transmission electron microscopy image exhibited that all the SeNPs were spherical and quasi-spherical with the diameters mainly distributed in 70-90 nm (average particles size was 87.82 ± 2.71 nm). X-ray diffraction suggested that the nanoparticles were composed of standard hexagonal crystalline Se with high purity. Fourier transform infrared spectroscopy indicated that some biomolecules such as hydroxyl, carboxyl and amino groups in the yeast cell-free extracts might be involved in the formation of SeNPs. Analyses of sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that two proteins with low molecular weight approximately ~ 16 and ~ 21 kDa were detected on the surface of SeNPs and in the extracts, which could play the role of natural stabilizers and confer stability to synthesized SeNPs; whereas, unbound proteins on the SeNPs surface could act as reducing agents. Antibacterial analysis showed that the SeNPs could inhibit Arthrobacter sp. W1 (Gram positive) but not E. coli BL21 (Gram negative), which could provide reference for antimicrobial application of biogenic SeNPs.