Colorimetric detection of paraquat in aqueous and fruit juice samples based on functionalized gold nanoparticles

Paraquat (PQ) is a kind of herbicide, which is highly toxic to human body. In this work, we proposed a fast and simple detection method for PQ in aqueous samples based on electrostatic interactions between modified gold nanoparticles (Au NPs) and PQ. Au NPs were first modified with sodium 3-mercapto-1-propanesulfonate (Au NPs-3MPS). 3MPS with negative charge can interact with nitrogen atoms of PQ with positive charge via electrostatic force. As a result, Au NPs-3MPS aggregated together. Accordingly, the color of Au NPs-3MPS colloid changed from red to blue-gray, and the UV–vis absorption spectrum changed accordingly. The detection limit of PQ is 0.1 mg/L by naked eyes, and 0.001 mg/L by UV–vis spectroscopy. Moreover, this detection method has good specific selectivity and anti-interference performance, and it has been successfully used for detecting PQ in real environmental samples and fruit juice samples.     

A Monte Carlo study on tissue dose enhancement in brachytherapy: a comparison between gadolinium and gold nanoparticles

The aim of this study was to quantify the dose enhancement by gadolinium and gold nanoparticles in brachytherapy. MCNPX Monte Carlo code was used to simulate four brachytherapy sources: (60)Co, (198)Au, (192)Ir, (169)Yb. To verify the accuracy of our simulations, the obtained values of dose rate constants and radial dose functions were compared with corresponding published values for these sources. To study dose enhancements, a spherical soft tissue phantom with 15 cm in radius was simulated. Gadolinium and gold nanoparticles at 10, 20 and 30 mg/ml concentrations were separately assumed in a 1 × 1 × 1 cm(3) volume simulating tumour. The simulated dose to the tumour with the impurity was compared to the dose without impurity, as a function of radial distance and concentration of the impurity, to determine the enhancement of dose due to the presence of the impurity. Dose enhancements in the tumour obtained in the presence of gadolinium and gold nanoparticles with concentration of 30 mg/ml, were found to be in the range of -0.5-106.1 and 0.4-153.1 % respectively. In addition, at higher radial distances from the source center, higher dose enhancements were observed. GdNPs can be used as a high atomic number material to enhance dose in tumour volume with dose enhancements up to 106.1 % when used in brachytherapy. Regardless considering the clinical limitations of the here-in presented model, for a similar source and concentration of nanoparticles, gold nanoparticles show higher dose enhancement than gadolinium nanoparticles and can have more clinical usefulness as dose enhancer material.     

The toxic effects of heavy metals on rat bone marrow in vitro erythropoiesis: protective role of hemin and zinc

The effects of gold (Au), lead (Pb), and cadmium (Cd) on rat bone marrow in vitro erythropoiesis (CFUE) were studied. Au was found to be significantly toxic to CFUE growth at concentrations as low as 10(-9) M whereas Pb and Cd displayed toxicity at 10(-7) M. Addition of Pb plus Cd in combination had a greater toxic effect on CFUE growth than when the metals were added singly, and the toxic effect of Cd was reduced when Zinc (Zn) was added in combination to the cultures. When hemin (10(-6) M) was added to cultures containing 10(-6) M Au, Pb, or Cd, CFUE numbers were obtained that were equivalent to control cultures without hemin. Thus, hemin exerted a protective effect on erythropoiesis in the presence of otherwise toxic amounts of Au, Pb, and Cd. It is concluded that Au, Pb, and Cd have toxic effects on in vitro erythropoiesis and that this toxicity may be overcome in part by Zn or hemin. The possible involvement of the heme biosynthetic and degradative pathways is discussed with respect to these results.     

Preparation and characterization of doxorubicin functionalized gold nanoparticles

In this paper, we have presented the demonstration of gold nanoparticles (Au NPs) functionalized with an anticancer drug, doxorubicin. Doxorubicin was assembled on gold via amino group. The reaction proceeded under mild acidic conditions. Au NPs could not be adsorbed on doxorubicin in alkaline solution because amino group was not protonated. However, under acidic conditions, protonation created a positively charged amino group thus adsorption was easier. The interaction between Au colloids and doxorubicin is believed to be electrostatic. High-resolution TEM was used for visualization of nanoparticles, which were found to retain their average size and shape. The method, demonstrated that doxorubicin could be attached to Au NPs in a controlled manner. Our research laid the foundation of a linking methodology through which hybrid multi drug and receptor labeled NPs could be created, which might serve as an alternative design for nanosized drug-delivery systems.     

Dose enhancement by various nanoparticles in prostate brachytherapy

The aim of this Monte Carlo study is to calculate dose enhancement in tumours by various nanoparticles in prostate brachytherapy using ¹²⁵I interstitial implants. ProstaSeed ¹²⁵I brachytherapy source was simulated using MCNPX Monte Carlo code. Dose rate constant, radial dose function and anisotropy function values were calculated and compared with previously published data. Dose enhancement factors (DEFs) were calculated for Fe₂O₃, Ag, Gd, Pt and Au nanoparticles with concentrations of 7, 18 and 30 mg/ml. Our source simulation was validated by comparing our results with previously published data. Maximum DEF values on the central transverse line, within the tumour, for Fe₂O₃, Ag, Gd, Pt and Au nanoparticles with 30 mg/ml concentration were 1.27, 1.15, 1.14, 1.32, 1.79, respectively. No general trend in DEF with increasing atomic number, or concentration of nanoparticles was observed. However, DEF was the highest for 30 mg/ml concentration of Au. The 50 % isodose line tightened toward the central point of the spherical tumour and the central 100 % isodose line expanded outward. The presence of nanoparticles in a prostate tumour increases the dose inside tumour and decreases the dose outside it, thus the treatment time and source activity can be decreased due to dose enhancement in the tumour. While more preclinical studies on other aspects are necessary, using nanoparticles can be proposed as a useful tool in prostate brachytherapy. Au nanoparticles with higher concentrations can be more useful for this purpose when compared to other nanoparticles.     

Size, concentration and incubation time dependence of gold nanoparticle uptake into pancreas cancer cells and its future application to X-Ray Drug Delivery System

One of the restrictions in the potential use of gold markers for medical imaging/tracking of harder tumors is its size. We propose to use gold nanoparticles which, due to its small size, can be administered conveniently via intravenous injection. One of the factors that determine the clinical utility of nanoparticles is the ability to enter cells. In this report, the stability of gold nanoparticles mixed with different media was determined by UV-vis spectroscopy. Gold nanoparticle size was confirmed by TEM. Intracellular uptake using different gold nanoparticle sizes, incubation times and concentrations were analyzed using Atomic Absorption Spectrometry (AAS). Temperature dependence uptake was also measured using AAS. The results showed that pancreas cancer cells uptake 20 nm gold nanoparticles preferentially compared to other gold nanoparticle sizes. Efficient accumulation of gold nanoparticles into pancreas cancer cells can be achieved at longer incubation time and higher concentration. The findings of this study will help in the design and optimization of the gold nanoparticle-based agents for therapeutic and diagnostic applications of X-ray Drug Delivery System.     

Melatonin prevents damage elicited by the organophosphorous pesticide diazinon on the mouse testis

Organophosphates like O,O-diethyl O-2-isopropyl-6-methyl pyrimidinyl-4-g-1-phosphorothioate (diazinon) are pesticides used worldwide, which can affect both animals and man even after a single exposure. Whereas their toxicity is due to acetylcholinesterase inhibition, their secondary toxic effects have been related to free oxygen radicals. This study evaluates the effects of a single dose of diazinon and melatonin-a powerful antioxidant-on plasmatic acetylcholinesterase activity and testis histopathology in adult mice 1 and 32 days post-treatment. Diazinon diminished the plasma acetylcholinesterase activity on day 1 post-treatment, although testosterone levels remained unaffected. Morphometrical analysis showed a decrease in seminiferous epithelium height (days 1 and 32), whereas an increase in testicular superoxide dismutase (SOD) activity was detected (day 32). Melatonin pretreatment prevented every alteration induced by diazinon, except the diminution of acetylcholinesterase plasmatic activity. Testicular damage might be due to elevated concentrations of free oxygen radicals released upon diazinon exposure, inducing alterations in the DNA and promoting local apoptosis; however, antioxidant pretreatment with melatonin prevents or diminishes this damage.     

生命体中的超氧化物歧化酶(综述)

超氧化物歧化酶(SOD)是生物体内清除超氧阴离子自由基的一种重要酶,它能有效地使机体抗御氧自由基的毒性.文章中综述了SOD的来源、分布、种类、结构性质制备、活性测定、化学修饰,以及在临床、食品、化妆品等方面的应用.     

Mercury in the Surface Soil and Cassava, Manihot esculenta (Flesh, Leaves and Peel) Near Goldmines at Bogoso and Prestea, Ghana

Mercury amalgamation is used indiscriminately in the recovery of gold by small-scale native gem winners in Ghana. Mercury is released into the environment in the form of wastewater, tailing and vapor from the roasting of amalgam to separate gold. The study looked at the levels of total mercury concentration in surface soil and cassava crop from farms located within the vicinities of Bogoso and Prestea Goldmines. The surface soil total mercury concentrations ranged between 125.29 and 352.52?μg/kg whiles cassava had between 66.60 and 195.47?μg/kg. The results showed proportionately more deposits at higher distances in 15?30?cm soil zone and less deposits at higher distances on leaves with relatively high uptake of the metal occurred at higher distances from the mines into the peels. These results suggest serious mercury pollution to the surface soil and the cassava crop but the speciation exercise showed that mercury is not in the free state, rather bound to hydroxides and organic compounds as complexes.     

Cytotoxic and Mutagenic Potential of Juglone: A Comparison of Free and Nano-encapsulated Form

Despite its evidenced beneficial herbicidal, antibacterial, antiviral, antifungal, and antioxidant effects, the application of juglone (5-hydroxy-1,4,-naphthoquinone) is limited due to its low water solubility and allelopathic and toxic effects. In recent years, research has aimed to overcome these limitations by increasing its solubility and controlling its release through nanoparticular systems. This is the first study to have synthesised and characterised juglone-loaded polymeric nanoparticles and compared them with free juglone for cytotoxicity in mouse (L929 fibroblasts) and alfalfa cells and for mutagenic potential in Salmonella typhimurium TA98/100. Mouse and plant cells treated with free and nano-encapsulated juglone showed a decrease in cell viability in a dose and time-dependent manner, but this effect was significantly lower with the nano-encapsulated form at lower doses. In the TA98 strain with S9, nano-encapsulated juglone did not exhibit mutagenic effects, unlike the free form. Since all results show that juglone encapsulation with polymeric nanoparticles reduced the toxic and mutagenic effects, it has a promising potential to be applied in medicine, food safety, and agriculture.Key words: alfalfa, L929 fibroblasts, nanoparticle, PLGA, S. typhimurium     

Physiological analysis of silver nanoparticles and AgNO3 toxicity to Spirodela polyrhiza

Silver nanoparticles (AgNPs) are commonly used in consumer products for their antibacterial activity. Silver nanoparticles may adversely influence organisms when released into the environment. The present study investigated the effect of AgNPs on the growth, morphology, and physiology of the aquatic plant duckweed (Spirodela polyrhiza). The toxicity of AgNPs and AgNO(3) was also compared. The results showed that silver content in plant tissue increased significantly with higher concentrations of AgNPs and AgNO(3) . Silver nanoparticles and AgNO(3) significantly decreased plant biomass, caused colonies of S. polyrhiza to disintegrate, and also resulted in root abscission. Physiological analysis showed that AgNPs and AgNO(3) significantly decreased plant tissue nitrate-nitrogen content, chlorophyll a (Chl a) content, chlorophyll a/b (Chl a/b), and chlorophyll fluorescence (Fv/Fm). Changes in soluble carbohydrate and proline content were also detected after both AgNO(3) and AgNPs treatment. However, after 192 h of recovery, total chlorophyll content increased, and Fv/Fm returned to control level. Median effective concentration (EC50) values for Chl a and phosphate content showed that AgNO(3) was more toxic than AgNPs (EC50 values: 16.10 ± 0.75 vs 7.96 ± 0.81 and 17.33 ± 4.47 vs 9.14 ± 2.89 mg?Ag?L(-1) , respectively), whereas dry-weight EC50 values showed that AgNPs were more toxic than AgNO(3) (13.39 ± 1.06 vs 17.67 ± 1.16 mg?Ag?L(-1) ).     

Solubility of nano-zinc oxide in environmentally and biologically important matrices

Increasing manufacture and use of engineered nanoparticles is leading to a greater probability for release of engineered nanoparticles into the environment and exposure to organisms. In particular, zinc oxide (ZnO) is toxic, although it is unclear whether this toxicity is due to the zinc oxide nanoparticles, dissolution to Zn(2+) , or some combination thereof. The goal of this study was to determine the relative solubilities of both commercially available and in-house synthesized ZnO in matrices used for environmental fate and transport or biological toxicity studies. Dissolution of ZnO was observed in nanopure water (7.18-7.40?mg/L dissolved Zn, as measured by filtration) and Roswell Park Memorial Institute medium (RPMI-1640) (～5?mg/L), but much more dissolution was observed in Dulbecco's modified Eagle's medium, in which the dissolved Zn concentration exceeded 34?mg/L. Moderately hard water exhibited low Zn solubility, likely because of precipitation of a Zn carbonate solid phase. Precipitation of a Zn-containing solid phase in RPMI also appeared to limit Zn solubility. Equilibrium conditions with respect to ZnO solubility were not apparent in these matrices, even after more than 1,000?h of dissolution. These results suggest that solution chemistry exerts a strong influence on ZnO dissolution and can result in limits on Zn solubility from precipitation of less soluble solid phases.     

Heavy metals and human spermatozoa. III. The toxicity of copper ions for spermatozoa

The dissolution of copper ions from copper metal into a saline medium was quantified using a colourimetric assay. The presence of spermatozoa enhanced this dissolution and increasing the protein content of the medium further increased the rate of dissolution. Approximately 17% of the copper released was either tightly bound to the spermatozoa or was within the cell and could not be removed by repeated washing. Once spermatozoa were immobilized, they could not be revived by washing and repeated changes of medium, by addition of copper specific-chelating agent or by extensive dialysis.

When the toxicity to spermatozoa of cuprous and cupric ions was compared with copper metal, it could be shown that the quantity of cupric ions required (0.2–0.4 mg/ml) was in excess of the total quantity of copper released into solution. The quantity of cuprous ion required (0.08–0.16 mg/ml) to exert similar toxic effects to copper, was within the range of copper released from the metal. Under the conditions of this study, it is possible that cuprous ion would be oxidised to the cupric form generating free radicals in the process. It is not known whether the toxic effect is due to the cuprous ion, per se, or to radicals generated in its oxidation.

Increasing the protein content of the medium to levels similar to low (8 mg/ml) and high (64 mg/ml) values reported in human uterine fluid increased the dissolution rate of copper but also offered some protection against the toxic effects of copper metal and cuprous and cupric ions.     

An Evaluation of the Toxicity of Contaminated Sediments from Waukegan Harbor, Illinois, Following Remediation

Waukegan Harbor in Illinois was designated as a Great Lakes Area of Concern due to high concentrations of sediment-associated polychlorinated biphenyls (PCBs). The objective of this study was to evaluate the toxicity of 20 sediment samples collected after remediation (primarily dredging) of Waukegan Harbor for PCBs. A 42-day whole sediment toxicity test with the amphipod Hyalella azteca (28-day sediment exposure followed by a 14-day reproductive phase) and sediment toxicity tests with Microtox(R) were conducted to evaluate sediments from Waukegan Harbor. Endpoints measured were survival, growth, and reproduction (amphipods) and luminescent light emission (bacteria). Survival of amphipods was significantly reduced in 6 of the 20 sediment samples relative to the control. Growth of amphipods (either length or weight) was significantly reduced relative to the control in all samples. However, reproduction of amphipods identified only two samples as toxic relative to the control. The Microtox basic test, conducted with organic extracts of sediments identified only one site as toxic. In contrast, the Microtox solid-phase test identified about 50% of the samples as toxic. A significant negative correlation was observed between reproduction and the concentration of three polynuclear aromatic hydrocarbons (PAHs) normalized to total organic carbon. Sediment chemistry and toxicity data were evaluated using sediment quality guidelines (consensus-based probable effect concentrations, PECs). Results of these analyses indicate that sediment samples from Waukegan Harbor were toxic to H. azteca contaminated at similar contaminant concentrations as sediment samples that were toxic to H. azteca from other areas of the United States. The relationship between PECs and the observed toxicity was not as strong for the Microtox test. The results of this study indicate that the first phase of sediment remediation in Waukegan Harbor successfully lowered concentrations of PCBs at the site. Though the sediments were generally not lethal, there were still sublethal effects of contaminants in sediments at this site observed on amphipods in long-term exposures (associated with elevated concentrations of metals, PCBs, and PAHs).     

Oxidative Stress Induced by Iron inHydrilla verticillata(l.f.) Royle: Response of Antioxidants

The effect of iron (FeCl₃) on chlorophyll content, lipid peroxidation product, potassium ion leakage (a measure of damage to the permeability barrier), and antioxidants was studied inHydrilla verticillata.The effect of iron-induced damage to the plant was compared with those ofN-ethyl maleimide (NEM), a sulfhydryl reagent, and cumene hydroperoxide (CHP), an organic peroxide known to induce lipid peroxidation by free radical formation. The level of lipid peroxidation product was increased in the plants treated with Fe, CHP, and CHP+NEM but not with NEM alone. A significant increase in potassium ion leakage to the external solution was observed by the addition of Fe, CHP, and CHP+NEM, while this did not increase significantly in NEM-treated plants. When NEM and CHP were added simultaneously, the results were the same as those obtained with high iron concentrations, suggesting a combined effect of thiol depletion and lipid peroxidation by Fe ions. In addition, the results indicated loss of glutathione (GSH) and increased oxidized glutathione (GSSG) under Fe stress, indicative of oxidative stress. The oxidative stress may increase the production of free radicals and subsequently resulted in peroxidation of lipids. Further, addition of iron increased the activity of superoxide dismutase (SOD) which may be due to enhanced production of oxygen free radical and related tissue damage. The results suggest that iron-induced damage in plants can be ascribed to a direct metal action on thiols and by toxic oxygen species. An increase in lipid peroxidation product and K⁺leakage are the primary responses of iron toxicity on membrane damage. However, the decrease in chlorophyll content is part of the overall expression of iron toxicity.     

Copper complexation and toxicity to freshwater zooplankton

The effect of copper on the growth rate of cyclopoid copepods and survival of rotifers was determined in natural water with and without addition of the complexing agent Tris. Free copper concentrations were estimated, both by cupric ion electrode and from the bioassay data, making use of the known complexing ability of Tris and the increase in total copper tolerated after Tris addition. Growth rates of copepods were directly related to free copper concentrations indicating that the copper-Tris complex was not toxic to these animals. Rotifer survival was similar at equivalent free copper concentrations in water with and without 1 mmole/L Tris, but addition of 3 mmole/L Tris resulted in slightly lower free copper at equivalently toxic total copper concentrations. Free copper concentrations calculated from bioassay data compared well with electrode measurements in all cases except when calculated using the 3 mmole/L Tris data for rotifers, when free copper concentrations were slightly overestimated.     

Astrocytes in health and disease

It is now known that astrocytes are not merely supporting cells but they also play an important role in neuronal functions. Astrocytes tightly ensheath neuronal synapses and regulate the excitation of neurons by the uptake of neurotransmitters; regulate the cerebral blood flow, cerebral fluid volume and extracellular concentrations of ions. They also supply fuel in the form of lactate and provide free radical scavengers such as glutathione for active neurons. These facts indicate that impaired function of astrocytes may lead to neuronal dysfunction. After brain injury (stroke, trauma or tumors) astrocytes are swollen and release active molecules such as glutamate or free radicals resulting in neuronal dysfunction. Thus, investigation of the molecular mechanisms of astrocyte function may reveal novel targets for the development of therapeutic tools in neuronal diseases.     

Scavenger effect of various cerebrovascular drugs

INTRODUCTION: Oxygen free radicals play an important role in several physiological and pathophysiological processes. In pathological circumstances they can modify and damage biological systems. As oxygen free radicals are involved in a wide range of diseases (cerebrovascular, cardiovascular, etc.), scavenging these radicals should be considered as an important therapeutic approach. AIM: In our in vitro study the antioxidant capacity of three cerebrovascular drugs (pentoxiphylline, piracetam and vinpocetine) was investigated. METHODS: Phenazine methosulphate (PMS) was applied to generate free radicals and thus increased red blood cell rigidity. Filtration technique and potassium leaking were used to detect the cellular damage and the scavenging effect of the examined drugs. RESULTS: At therapeutic serum concentration only vinpocetine had significant (p < 0.01) scavenging activity which protective effect was even better at higher concentrations. Pentoxiphylline and piracetam did not have significant antioxidant capacity at therapeutic concentrations, but increasing the concentrations (pentoxiphylline at hundred times, while piracetam at ten times higher concentrations) led to a significant (p < 0.01) scavenger effect. CONCLUSION: The authors' findings suggest that this pronounced antioxidant effect of vinpocetine and even the milder scavenging capacity of piracetam which tends to cumulate in the cerebral tissue may be of value in the treatment of patients with cerebrovascular disorders.     

Antioxidant status in children with protein-energy malnutrition (PEM) living in Cairo, Egypt.

OBJECTIVES: Free radicals are implicated in many diseases. The rise in free radicals associated with antioxidant deficiency results in tissue damage. The pathogenesis of oedema and anaemia commonly found in children with protein-energy malnutrition (PEM) has been suggested to be caused by an imbalance between the production of toxic radicals and their safe disposal. The aim of this study was to evaluate antioxidant status in children with PEM. DESIGN: A total of 68 children (age range: 3 months to 3 years) living in Cairo, Egypt were recruited. Forty-six of these subjects had different degrees of PEM; they were admitted at the Abo-Elrish Hospital, Cairo. Of these, 26 children had kwashiorkor (KWO) and twenty had marasmus (MAR). Twenty-two age and sex matched healthy well-nourished children were recruited from the local community, and used as controls. METHODS: The antioxidant status of the study population was determined by measuring copper-zinc superoxide dismutase (Cu-Zn, SOD) in red blood cells, glutathione peroxidase (GPX) in whole blood, and ceruloplasmin in plasma. In addition, the plasma levels of trace-elements involving antioxidant activities, such as copper (Cu), zinc (Zn), and selenium (Se) were determined, along with a select group of vitamins. The latter included vitamin A (retinol), vitamin E (alpha-tocopherol) and vitamin C (ascorbic acid). RESULTS: The mean whole blood GPX activity along with plasma levels of vitamins A, E and C as well as ceruloplasmin, Cu and Se were all lower in children with either KWO or MAR than their corresponding control subjects. The erythrocyte SOD activity, on the other hand, was increased while the plasma Zn concentrations were either increased or not changed in the malnourished children. It was of interest that while haemoglobin concentrations were decreased, the plasma free iron (Fe) levels were significantly increased in children with KWO. CONCLUSIONS: The significant increase in red cell SOD activity associated with the decrease in plasma ceruloplasmin, antioxidant vitamins and the whole blood GPX activity in PEM children suggest that these children are potentially susceptible to high oxidative stress. An elevated plasma Fe concentrations, especially with KWO may augment the harmful effect of free radicals with a clinical consequence of oedema.     

Polymer gels impregnated with gold nanoparticles implemented for measurements of radiation dose enhancement in synchrotron and conventional radiotherapy type beams

Normoxic type polyacrylamide gel (nPAG) dosimeters are established for dose quantification in three-dimensions for radiotherapy and hence represent an adequate dosimeter for quantification of the dose variation due to the existence of the gold nanoparticles (AuNPs) in the target during irradiation. This work compared the degree of polymerisation in gel doped with nanoparticles (nPAG-AuNP) with control gel samples when irradiated by various sources. Samples were irradiated with a synchrotron radiation source of mean energy 125?keV, 80?kV X-ray beams from superficial therapy machine (SXRT), 6?MV X-rays and 6?MeV electron beams from linear accelerator. Analysis of the dose-response relation was used to determine a dose enhancement factor (DEF) of 1.76?±?0.34 and 1.64?±?0.44 obtained for samples irradiated with kilovoltage X-rays energy from synchrotron source and SXRT respectively. Similarly, including AuNPs in gel results in a DEF of approximately 1.37?±?0.35 when irradiated by an electron beam and 1.14?±?0.28 for high energy X-ray beams. The results demonstrate the use of AuNPs embedded in polymer gels for measuring the enhancement of radiation caused by metallic nanoparticles.