Effects of silver nanoparticles with different dosing regimens and exposure media on artificial ecosystem.

Due to the wide use of silver nanoparticles (AgNPs) in various fields, it is crucial to explore the potential negative impacts on the aquatic environment of AgNPs entering into the environment in different ways. In this study, comparative experiments were conducted to investigate the toxicological impacts of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) with two kinds of dosing regimens, continuous and one-time pulsed dosing, in different exposure media (deionized water and XiangJiang River water). There were a number of quite different experimental results (including 100% mortality of zebrafish, decline in the activity of enzymes, and lowest number and length of adventitious roots) in the one-time pulsed dosing regimen at high PVP-AgNP concentration exposure (HOE) compared to the three other treatments. Meanwhile, we determined that the concentration of leached silver ions from PVP-AgNPs was too low to play a role in zebrafish death. Those results showed that HOE led to a range of dramatic ecosystem impacts which were more destructive than those of other treatments. Moreover, compared with the continuous dosing regimen, despite the fact that higher toxicity was observed for HOE, there was little difference in the removal of total silver from the aquatic environment for the different dosing regimens. No obvious differences in ecological impacts were observed between different water columns under low concentration exposure. Overall, this work highlighted the fact that the toxicity of AgNPs was impacted by different dosing regimens in different exposure media, which may be helpful for assessments of ecological impacts on aquatic environments.

Advancement of Ag-Graphene Based Nanocomposites: An Overview of Synthesis and Its Applications.

Graphene has been employed as an excellent support for metal nanomaterials because of its unique structural and physicochemical properties. Silver nanoparticles (AgNPs) with exceptional properties have received considerable attention in various fields; however, particle aggregation limits its application. Therefore, the combination of AgNPs and graphene based nanocomposites (Ag-graphene based nanocomposites) has been widely explored to improve their properties and applications. Excitingly, enhanced antimicrobial, catalytic, and surface enhanced Raman scattering properties are obtained after their combination. In order to have a comprehensive knowledge of these nanocomposites, this Review highlights the chemical and biological synthesis of Ag-graphene nanocomposites. In particular, their applications as antimicrobial agents, catalysts, and sensors in biomedicine, agricultural protection, and environmental remediation and detection are covered. Meanwhile, the factors that influence the synthesis and applications are also briefly discussed. Furthermore, several important issues on the challenges and new directions are also provided for further development of these nanocomposites.

Applications of white rot fungi in bioremediation with nanoparticles and biosynthesis of metallic nanoparticles.

White rot fungi (WRF) are important environmental microorganisms that have been widely applied in many fields. To our knowledge, the application performance of WRF in bioremediation can be greatly improved by the combination with nanotechnology. And the preparation of metallic nanoparticles using WRF is an emerging biosynthesis approach. Understanding the interrelation of WRF and nanoparticles is important to further expand their applications. Thus, this mini-review summarizes the currently related reports mainly from the two different point of views. We highlight that nanoparticles as supports or synergistic agents can enhance the stability and bioremediation performance of WRF in wastewater treatment and the biosynthesis process and conditions of several important metallic nanoparticles by WRF. Furthermore, the potential toxicity of nanoparticles on WRF and challenges encountered are also discussed. Herein, we deem that this mini-review will strengthen the basic knowledge and provide valuable insight for the applications of WRF and nanoparticles.

Cadmium-containing quantum dots: properties, applications, and toxicity.

The marriage of biology with nanomaterials has significantly accelerated advancement of biological techniques, profoundly facilitating practical applications in biomedical fields. With unique optical properties (e.g., tunable broad excitation, narrow emission spectra, robust photostability, and high quantum yield), fluorescent quantum dots (QDs) have been reasonably functionalized with controllable interfaces and extensively used as a new class of optical probe in biological researches. In this review, we summarize the recent progress in synthesis and properties of QDs. Moreover, we provide an overview of the outstanding potential of QDs for biomedical research and innovative methods of drug delivery. Specifically, the applications of QDs as novel fluorescent nanomaterials for biomedical sensing and imaging have been detailedly highlighted and discussed. In addition, recent concerns on potential toxicity of QDs are also introduced, ranging from cell researches to animal models.

Fluorescent and colorimetric sensors for environmental mercury detection.

Exposure to mercury ions can damage the human brain, the nervous system, the endocrine system, and other biological systems. Much effort has therefore been made to develop real-time monitoring of mercury variations, and many mercury-ion sensors have been reported recently. In this review, mercury-ion sensors reported since 2008 are described and discussed. The sensors are classified as molecular, nanomaterial based, and others. Molecular sensors are based on chemical and hydrogen bond formation, and the other types are based on changes in the materials used.

Fluorescence chemosensors for hydrogen sulfide detection in biological systems.

A comprehensive review of the development of H2S fluorescence-sensing strategies, including sensors based on chemical reactions and fluorescence resonance energy transfer (FRET), is presented. The advantages and disadvantages of fluorescence-sensing strategies are compared with those of traditional methods. Fluorescence chemosensors, especially those used in FRET sensing, are highly promising because of their low cost, technical simplicity, and their use in real-time sulfide imaging in living cells. Potential applications based on sulfate reduction to H2S, the relationship between sulfate-reducing bacteria activity and H2S yield, and real-time detection of sulfate-reducing bacteria activity using fluorescence sensors are described. The current challenges, such as low sensitivity and poor stability, are discussed.

Sclerosing Stromal Ovarian Tumor Combined with Early Onset Severe Preeclampsia. A Case Report.

BACKGROUND: Sclerosing stromal tumor (SST) of the ovary is an extremely rare, benign, sex cord-stromal tumor. The tumor consists of cells with the multilineage potential of undifferentiated mesenchymal cells and the ability to secrete estrogen or androgen. Current research suggests that the tumor originates in the ovarian cortex. SSTs of the ovary are predominantly found in young women aged 20-30 years; information describing SST during pregnancy is limited. CASE: We report a case of SST of the ovary combined with early onset severe preeclampsia. CONCLUSION: We document the clinical and pathological characteristics of the patient's disease, including the effects on the pregnancy and fetus.

Alteration of culture fluid proteins by cadmium induction in Phanerochaete chrysosporium.

Microorganisms need to resist the hazards posed by heavy metals during the process of metal adsorption. Phanerochaete chrysosporium is a fungus that is efficiently used for heavy-metal biosorption in wastewater treatment. Extraction and analysis of proteins induced by heavy metals can help to understand the regulatory mechanisms of P. chrysosporium in wastewater treatment. In this study, P. chrysosporium was exposed to 50 µM cadmium nitrate. A maximum cadmium adsorption capability of 77.1 mg/g dry biomass was found after 65 h, which was accompanied by a relatively higher protein concentration. After separation of the culture fluid proteins by two-dimensional difference gel electrophoresis (2D-DIGE), three differentially expressed proteins were detected from 17 spots. By using 2D-DIGE, followed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS), glutathione S-transferase, glyceraldehyde-3-phosphate dehydrogenase, and malate dehydrogenase were identified. All three enzymes play important roles in the oxidative stress caused by cadmium.

A tyrosinase biosensor based on ordered mesoporous carbon-Au/L-lysine/Au nanoparticles for simultaneous determination of hydroquinone and catechol.

A novel biosensor was developed based on tyrosinase immobilization with ordered mesoporous carbon-Au (OMC-Au), L-lysine membrane and Au nanoparticles on a glassy carbon electrode (GCE). It was applied for the simultaneous determination of dihydroxybenzene isomers using differential pulse voltammetry (DPV). The tyrosinase/OMC-Au/L-lysine/Au film was characterized by scanning electron microscopy (SEM) and impedance spectra. Under optimized conditions, the DPV study results for two isomers, hydroquinone (HQ, 1,4-dihydroxybenzene) and catechol (CC, 1,2-dihydroxybenzene) showed low peak potentials, and the peak-to-peak difference was about 135.85 mV, which ensured the anti-interference ability of the biosensor and made simultaneous detection of dihydroxybenzene isomers possible in real samples. DPV peak currents increased linearly with concentration over the range of 4.0 × 10(-7) to 8.0 × 10(-5) M, and the detection limits of hydroquinone and catechol were 5 × 10(-8) M and 2.5 × 10(-8) M (S/N = 3), respectively. The tyrosinase biosensor exhibited good repeatability and stability. In addition, the response mechanism of enzyme catalysed redox on the OMC-Au/L-lysine/Au film modified electrode based on electrochemical study was discussed. The proposed method could be extended for the development of other enzyme-based biosensors.

Cadmium removal and 2,4-dichlorophenol degradation by immobilized Phanerochaete chrysosporium loaded with nitrogen-doped TiO2 nanoparticles.

Phanerochaete chrysosporium has been identified as an effective bioremediation agent for its biosorption and degradation ability. However, the applications of P. chrysosporium are limited owing to its long degradation time and low resistance to pollutants. In this research, nitrogen-doped TiO2 nanoparticles were loaded on P. chrysosporium to improve the remediation capacity for pollutants. The removal efficiencies were maintained at a high level: 84.2% for Cd(II) and 78.9% for 2,4-dichlorophenol (2,4-DCP) in the wide pH range of 4.0 to 7.0 in 60 h. The removal capacity of immobilized P. chrysosporium loaded with nitrogen-doped TiO2 nanoparticles (PTNs) was strongly affected by the initial Cd(II) and 2,4-DCP concentrations. The hyphae of PTNs became tight, and a large amount of crystals adhered to them after the reaction. Fourier transform infrared spectroscopy showed that carboxyl, amino, and hydroxyl groups on the surface of PTNs were responsible for the biosorption. In the degradation process, 2,4-DCP was broken down into o-chlorotoluene and 4-hexene-1-ol. These results showed that PTNs is promising for simultaneous removal of Cd(II) and 2,4-DCP from wastewater.

Aggressive fibromatosis near the incision after cervical spinal cord ependymoma: A case report.

Aggressive fibromatosis (AF), also known as ligamentoid fibromatosis and desmoid tumor, is a fibroblast clonoproliferative lesion located in the deep soft tissue. The present study reports the case of a 36-year-old female with AF who underwent cervical spinal cord ependymoma surgery. AF developed in the soft tissue of the neck adjacent to the incision site. The size of the neck AF increased rapidly over 2 years, and due to discomfort, the patient underwent initial surgical resection without any other combined treatment methods. When the patient was routinely reviewed at 6 months post-surgery, a recurrence of AF of the neck was found. The patient was recommended surgical resection and radiotherapy. This case report should improve the understanding of clinicians with regard to AF, and help the diagnostic process and treatment plan.

Responses of Phanerochaete chrysosporium to toxic pollutants: physiological flux, oxidative stress, and detoxification.

The white-rot fungus Phanerochaete chrysosporium has been widely used for the treatment of waste streams containing heavy metals and toxic organic pollutants. The development of fungal-based treatment technologies requires detailed knowledge of the relationship between bulk water quality and the physiological responses of fungi. A noninvasive microtest technique was used to quantify real-time changes in proton, oxygen, and cadmium ion fluxes following the exposure of P. chrysosporium to environmental toxic (2,4-dichlorophenol and cadmium). Significant changes in H(+) and O(2) flux occurred after exposure to 10 mg/L 2,4-dichlorophenol and 0.1 mM cadmium. Cd(2+) flux decreased with time. Reactive oxygen species formation and antioxidant levels increased after cadmium treatment. Superoxide dismutase activity correlated well with malondialdehyde levels (r(2) = 0.964) at low cadmium concentrations. However, this correlation diminished and malondialdehyde levels significantly increased at the highest cadmium concentration tested. Real-time microscale signatures of H(+), O(2), and Cd(2+) fluxes coupled with oxidative stress analysis can improve our understanding of the physiological responses of P. chrysosporium to toxic pollutants and provide useful information for the development of fungal-based technologies to improve the treatment of wastes cocontaminated with heavy metals and organic pollutants.

Removal of Cd(II), Cu(II) and Zn(II) from aqueous solutions by live Phanerochaete chrysosporium.

Living Phanerochaete chrysosporium mycelia were used to remove heavy metals of Cd(II), Cu(II) and Zn(II) in auqeous solution. The uptake of heavy metal by the mycelia was dependent on the environmental conditions. The optimum biosorption conditions of Cd(II), Cu(II), and Zn(II) were pH 5.5-6.5 at 37 degrees C, and 6 h. Under these conditions, the fungal biosorbent removed Cd(II), Cu(II), and Zn(II) rapidly and efficiently with maximum metal removal capacities of 59.77 mg/g, 74.78 mg/g, and 54.12 mg/g, respectively. The pseudo second-order kinetic model was superior to the pseudo first-order kinetic model, which indicated that the change ofthe surface sorption sites number was proportional to the square ofthe remaining unoccupied surface sites number. Fourier transform infrared (FT-IR) spectra indicated that hydroxyl and carboxyl groups were relevant to biosorption. Some crystal particles were found on the surface of the P. chrysosporium under scanning electron microscopy. Energy dispersive X-ray analysis and FT-IR revealed that amino acids and proteins were involved in binding metal ions. The results demonstrated that P. chrysosporium was a good potential biosorbent for adsorbing heavy metals.

Simultaneous cadmium removal and 2,4-dichlorophenol degradation from aqueous solutions by Phanerochaete chrysosporium.

Phanerochaete chrysosporium has been recognised as an effective bioremediation agent due to its unique degradation to xenobiotic and biosorption ability to heavy metals. However, few studies have focused on the simultaneous removal of heavy metals and organic pollutants. The aim of this work was to study the feasibility of simultaneous cadmium removal and 2,4-dichlorophenol (2,4-DCP) degradation in P. chrysosporium liquid cultures. The removal efficiencies were pH dependent and the maximum removal efficiencies were observed at pH 6.5 under an initial cadmium concentration of 5 mg/L and an initial 2,4-DCP concentration of 20 mg/L. The removal efficiencies for cadmium and 2,4-DCP reached 63.62% and 83.90%, respectively, under the optimum conditions. The high production levels of lignin peroxidase (7.35 U/mL) and manganese peroxidase (8.30 U/mL) resulted in an increase in 2,4-DCP degradation. The protein content decreased with increasing cadmium concentration. The surface characteristics and functional groups of the biomass were studied by scanning electron microscopy and a Fourier-transformed infrared spectrometer. The results showed that the use of P. chrysosporium is promising for the simultaneous removal of cadmium and 2,4-DCP from liquid media.

Antimicrobial efficacy and mechanisms of silver nanoparticles against Phanerochaete chrysosporium in the presence of common electrolytes and humic acid.

In this study, influences of cations (Na+, K+, Ca2+, and Mg2+), anions (NO3-, Cl-, and SO42-), and humic acid (HA) on the antimicrobial efficacy of silver nanoparticles (AgNPs)/Ag+ against Phanerochaete chrysosporium were investigated by observing cell viability and total Ag uptake. K+ enhanced the antimicrobial toxicity of AgNPs on P. chrysosporium, while divalent cations decreased the toxicity considerably, with preference of Ca2+ over Mg2+. Impact caused by a combination of monovalent and divalent electrolytes was mainly controlled by divalent cations. Compared to AgNPs, however, Ag+ with the same total Ag content exhibited stronger antimicrobial efficacy towards P. chrysosporium, regardless of the type of electrolytes. Furthermore, HA addition induced greater microbial activity under AgNP stress, possibly originating from stronger affinity of AgNPs over Ag+ to organic matters. The obtained results suggested that antimicrobial efficacy of AgNPs was closely related to water chemistry: addition of divalent electrolytes and HA reduced the opportunities directly for AgNP contact and interaction with cells through formation of aggregates, complexes, and surface coatings, leading to significant toxicity reduction; however, in monovalent electrolytes, the dominating mode of action of AgNPs could be toxic effects of the released Ag+ on microorganisms due to nanoparticle dissolution.

Efficient removal of methylene blue from aqueous solutions using magnetic graphene oxide modified zeolite.

In this study, magnetic graphene oxide modified zeolite (Cu-Z-GO-M) composites with two different ratios of GO to zeolite (named Cu-Z-GO-M 1:2 and Cu-Z-GO-M 1:1) were synthesized by solid-state dispersion (SSD) method. The properties of zeolite-based composites were characterized by SEM, XRD, FTIR, XPS, and magnetization curves. In order to understand the pollutant removal performance of the as-prepared composites, methylene blue (MB) was used as the target pollutant in adsorption experiments. The removal efficiency of MB onto Cu-Z-GO-M composite was enhanced obviously with pH > 9. The adsorption capacities of MB onto Cu-Z-GO-M 1:1 were 82.147, 89.315, 97.346 mg/g at 298, 308, and 318 K, respectively. The removal ability of MB increased with the increase of GO content in modified composites. The adsorption behavior can be well described using a pseudo-second-order kinetic and Freundlich isotherm model. The thermodynamic analysis indicated the MB adsorption by Cu-Z-GO-M was a spontaneous and endothermic reaction. The results showed that the prepared Cu-Z-GO-M composite could be a promising adsorbent with good adsorption capacity and reusability for MB removal from wastewater.

Alleviation of heavy metal and silver nanoparticle toxicity and enhancement of their removal by hydrogen sulfide in Phanerochaete chrysosporium.

Hydrogen sulfide (H2S), an important cellular signaling molecule, plays vital roles in mediating responses to biotic/abiotic stresses. Influences of H2S on metal removal, cell viability, and antioxidant response of Phanerochaete chrysosporium upon exposure to heavy metals and silver nanoparticles (AgNPs) in the present study were investigated. An enhancement in Pb(ΙΙ) removal with an increase in concentration of the H2S donor sodium hydrosulfide (NaHS) was observed, and the maximum removal efficiencies increased by 31% and 17% under 100 and 200 mg/L Pb(ΙΙ) exposure, respectively, in the presence of 500 µM NaHS. Application of 500 µM NaHS increased the cell viability by 15%-39% under Pb(II) stress (10-200 mg/L) with relative to the untreated control. Increase in total Ag uptake and cell survival was also elicited by NaHS in a concentration-dependent manner under AgNP stress. Meanwhile, activities of superoxide dismutase and catalase were significantly enhanced with the introduction of NaHS under stresses of Pb(II), Cd(II), Cu(II), Zn(II), Ni(II), and AgNPs. The inhibition in lipid peroxidation and oxidative stress was observed in P. chrysosporium cells exposed to these toxicants following NaHS pretreatment, which could be attributed to the upregulation in antioxidant enzymes. The results obtained suggest that H2S can alleviate heavy metals and AgNP-induced toxicity to P. chrysosporium and improve the removal efficiency of these toxicants from wastewater.

Fabrication of ploydopamine-kaolin supported Ag nanoparticles as effective catalyst for rapid dye decoloration.

In this work, silver nanoparticles supported on polydopamine-kaolin composite (PDA-kaolin-Ag) was fabricated by an in-situ reduction method with PDA as both reductant and stabilizer. The morphology, composition, and structure of PDA-kaolin-Ag composite were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic reduction tests confirmed the importance of PDA modification and high catalytic activities of this as-prepared PDA-kaolin-Ag composite towards a model dye Rhodamine B. The catalytic reduction processes followed pseudo-first order kinetics. Meanwhile, this catalyst showed excellent stability and recyclability for dye decoloration. Furthermore, this composite also exhibited good catalytic performance on methylene blue, methyl orange, and Congo red. These results suggest that PDA-kaolin-Ag composites can be used as efficient and cost-effective catalyst for the decoloration of various organic dyes.

Preparation of silver-nanoparticle-loaded magnetic biochar/poly(dopamine) composite as catalyst for reduction of organic dyes.

In the present study, Ag nanoparticles loaded on polydopamine coated magnetic biochar (MC-PDA-Ag) catalyst was prepared by in-situ reduction approach. The morphology, composition, and structure of MC-PDA-Ag were characterized by the transmission electron microscopy (TEM), the scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). Catalytic reduction tests confirmed that MC-PDA-Ag catalyst showed excellent catalytic performance on the model dyes (MB, RhB, and MO) in the presence of NaBH4. The reduction efficiency of MB exceeded 90% by MC-PDA-Ag even under different initial pH (3-11) and different NaNO3 concentrations (0-0.5 M) within 5 min, indicating that the MC-PDA-Ag catalyst has potential strong universal adaptability in dye wastewater treatment. Furthermore, no significant decrease in catalytic ability was observed after 5 recycles, and the catalyst could be separated by an external magnet, indicating that this as-prepared catalyst exhibited high reusability and easy separability. These results suggest that MC-PDA-Ag composite catalyst can be used as an efficient catalyst for the reduction of organic dyes, and shows great potential application in wastewater treatment.

Influences of pH and metal ions on the interactions of oxytetracycline onto nano-hydroxyapatite and their co-adsorption behavior in aqueous solution.

In this study, interaction of oxytetracycline (OTC) onto nano-hydroxyapatite (nHAP) was evaluated as affected by pH and metal ions. Results showed that the adsorption process of OTC was highly pH- and metallic species-dependent. The amount of sorbed OTC at four pH were in the order of pH 8.0 > pH 10.0 > pH 5.5 > pH 3.0 and reached equilibrium around 120 min, indicating adsorption affinity of four species to nHAP followed the order of OTC- > OTC2- > OTC±â€¯> OTC+. Adding metal ions greatly increased the distribution coefficient (Kd) of OTC between adsorbents and aqueous phases, following the order of Fe3+ > Cu2+ > Pb2+ > Cd2+ = Ca2+ in the pH range of 3.0-10.0. Moreover, the co-adsorption behavior of OTC and heavy metals onto nHAP was also explored at pH 5.5 for the first time. OTC adsorption was significantly enhanced with the co-existence of 0.25 mmol/L Cu2+ or Pb2+. Inversely, the presence of 0.25 mmol/L OTC slightly led to the improvement of Cu2+ adsorption and depression of Pb2+ adsorption, yet Pb2+ adsorption was obviously promoted with the co-existence of 0.1 mmol/L OTC. Meanwhile, adsorption of OTC and Cd2+ showed unapparent variation in single or binary systems. The bridging effect involving metal ions, O- and N- containing groups in OTC molecules, and CaOH or POH sites of nHAP resulted in the formation of ternary complexes which were responsible for the promotion of their adsorption, while dissolution-precipitation was another key mechanism with the co-existence of Pb2+.