Aggregation and dispersion of silver nanoparticles in exposure media for aquatic toxicity tests

Silver nanoparticles (AgNPs) are currently being very widely used in industry, mainly because of their anti-bacterial properties, with applications in many areas. Once released into the environment, the mobility, bioavailability, and toxicity of AgNPs in any ecosystem are dominated by colloidal stability. There have been studies on the stability or the aggregation of various nanoparticles (NPs) under a range of environmental conditions, but there is little information on fully characterised AgNPs in media used in (eco)toxicity studies. In this study, monodisperse 7, 10 and 20 nm citrate-stabilised AgNPs were synthesised, characterised and then fractionated and sized by flow field-flow fractionation (FFF) and measured with dynamic light scattering (DLS) in different dilutions of the media recommended by OECD for Daphnia magna (water flea) toxicity testing. Stability of NPs was assessed over 24 h, and less so over 21 days, similar time periods to the OECD acute and chronic toxicity tests for D. magna. All particles aggregated quickly in the media with high ionic strength (media1), resulting in a loss of colour from the solution. The size of particles could be measured by DLS in most cases after 24h, although a fractogram by FFF could not be obtained due to aggregation and polydispersity of the sample. After diluting the media by a factor of 2, 5 or 10, aggregation was reduced, although the smallest NPs were unstable under all media conditions. Media diluted up to 10-fold in the absence of AgNPs did not induce any loss of mobility or fecundity in D. magna. These results confirm that standard OECD media causes aggregation of AgNPs, which result in changes in organism exposure levels and the nature of the exposed particles compared to exposure to fully dispersed particles. Setting aside questions of dose metrics, significant and substantial reduction in concentration over exposure period suggests that literature data are in the main improperly interpreted and nanoparticles are likely to have far greater biological effects than suggested thus far by poorly controlled exposures. We recommend that the standard OECD media is diluted by a factor of ca. 10 for use with these NPs and this test media, which reduces AgNP aggregation without affecting the viability of the text organism.     

Toxicity evaluation of single and mixed antifouling biocides measured with acute toxicity bioassays

Antifouling biocides used in boat paints were analyzed with a battery of toxicity bioassays to evaluate the toxic effects of these compounds on Vibrio fischeri, Daphnia magna and Selenastrum capricornotum. The antifoulants tested were Irgarol 1051, Kathon 5287, chlorothalonil, diuron, dichlofluanid, 2-thiocyanomethylthiobenzothiazole (TCMTB) and tributyltin (TBT). In most cases, the sensitivity of the organisms towards the toxicants followed the order: S. capricornotum > D. magna > V. fischeri. Toxicity by concentration level had the following order: TBT=Kathon 5287>chlorothalonil>Irgarol 1051>diuron>dichlofluanid>TCMTB for S. capricornotum. For D. magna (48 h test), the toxicity order of compounds was TBT>Kathon 5287>chlorothalonil>TCMTB>dichlofluanid>Irgarol 1051>diuron. For V. fischeri (30 min test), the compound toxicity had the following order: Kathon 5287>TBT>TCMTB>dichlofluanid>Irgarol 1051>chlorothalonil.Degradation products of Irgarol 1051 and diuron were also tested. Degradation product of Irgarol 1051 was found to be less toxic to the crustacean and the microalga but more toxic to the bacterium. Degradation products of diuron were less toxic to the microalga in comparison with the bacterium. For mixtures of compound, toxicities were additive in only 33% of the cases and 21% of mixtures were less toxic than expected based on the sum of concentrations of toxicants (antagonistic effect). Synergistic enhancements of toxicity were observed for a majority (46%) of the mixtures.The average reproducibility of the EC₅₀ and LOEC measurements was 27, 24 and 28%, respectively, in the V. fischeri, S. capricornotum and D. magna bioassays. For single compound, the reproducibility of EC₅₀ was better than ±20% for a vast majority of the measurements with the V. fischeri system, thus agreeing closely with the reported reproducibility values for this relatively well-known assay.     

Comparative evaluation of the effects of pesticides in acute toxicity luminescence bioassays

Acute toxicity of pesticides in water was assessed singly and in mixtures using the responses of the luminescent bacterium Vibrio fischeri (BioTox™), the aquatic invertebrate Daphnia magna (Daphtoxkit™), and the MitoScan™ assay. The latter utilized fragmented mitochondria to enzymatically convert β-nicotinamide adenine dinucleotide (NADH) to its oxidized form, NAD⁺. The rate of the conversion being sensitive to type and concentration of toxicants. The pesticides tested were Carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate), Cyromazine (N-cyclopropyl-1,3,5-triazine-2,4,6-triamine), Fenamiphos (ethyl 4-methylthio-m-tolyl isopropylphosphoramidate), and Formetanate (3-dimethylaminomethyleneiminophenyl methylcarbamate). The toxicity bioassays were characterized in terms of relative sensitivity, reproducibility, range of the linear response, and the ability to reveal synergistic/antagonistic interactions among toxicants. The D. magna assay was the most sensitive and best able to detect toxic interactions of mixtures. Also, unlike the other assays used, the response of the daphnid system was linear over a 10-fold change in pesticide concentration. Relative to the BioTox™, the MitoScan™ was 2- to 11-fold more sensitive for the compounds and mixtures tested. The EC₅₀ reproducibility of all tests was within ±20% coefficient of variation; however, the lowest observable effect concentration (LOEC) were only reproducible to ±35% on average. Cyromazine was the least toxic of the pesticides tested. To test the predictive value of the concept of concentration addition, toxicities of binary and quaternary mixtures of four different pesticides were analyzed. Synergistic/antagonistic responses were most frequently observed in testing with D. magna. Synergistic/antagonistic effects were seen only in 25 and 50% of the cases with the BioTox™ and the MitoScan™ assays, respectively.     

European ring exercise on water toxicity using different bioluminescence inhibition tests based on Vibrio fischeri, in support to the implementation of the water framework directive

An inter-laboratory comparison exercise was conducted under the European Union funded project entitled: Screening Methods for Water Data Information in Support of the Implementation of the Water Framework Directive (SWIFT-WFD) and coordinated by the Consejo Superior de Investigaciones Científicas (CSIC), in order to evaluate the reproducibility of different toxicity tests based on the bioluminescence inhibition of Vibrio fischeri, for the rapid water toxicity assessment.For the first time, this type of exercise has been organized in Europe, and using different tests based on the same principle. In this exercise, 10 laboratories from 8 countries (Austria, Cyprus, Germany, Greece, Italy, Portugal, Romania, and Spain) took place, and a total number of 360 samples were distributed.During the exercise, six series of six samples were analyzed along 5 months. Every batch of samples was composed by three real samples and three standard solutions. The real samples were: a raw influent and the effluent of a wastewater treatment plant (WWTP), and a sample from a first settlement of the WWTP spiked with a mixture of toxicant standards.A final number of 330 (91.7%) samples was analyzed, 3300 values in duplicate were collected, and the results for each sample were expressed as the 50% effective concentration (EC₅₀) values calculated through five points of dilution inhibition curves, after 5 and 15 min of incubation times.A statistical study was initiated using 660 results. The mean values, standard deviations (σ), variances (σ²), and upper and lower warning limits (UWL and LWL) were obtained, using the EC₅₀ values calculated with the result from the participating laboratories.The main objectives of this toxicity ring study were to evaluate the repeatability (r) and reproducibility (R) when different laboratories conduct the test, the influence of complex matrix samples, the variability between different tests based on the same principle, and to determine the rate at which participating laboratories successfully completed tests initiated.In this exercise, the 3.93% toxicity values were outliers according with the Z-score values and the Dixon test. The samples with the greater number of outliers were those with the smallest variability coefficient, corresponding to the greater and the smaller toxicity level.No relation was found through the cluster analysis, between the final results and the different commercial devices involved. Testing by multiple commercial devices did not appear to reduce the precision of the results, and the variability coefficient for the exercise was nearby to the average value for past editions carried out at national level, where the different participants used the same commercial device.Stability of samples was also followed during the exercise. While statistical significance differences were not found for the greater part of samples, for the sample from the WWTP influent, a significant decrease of the toxicity value was found along this study. Nevertheless, this was a type of sample with a high toxicity level during all the exercise.On the other hand, in order to obtain the chemical characterization of real samples, those were analyzed by chromatographic techniques, using different sequential solid phase extraction (SSPE) procedures, followed by liquid chromatography coupled with mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). Good agreement was found between the chemical analysis results and the toxicity level of the samples.     

Comparison of laser ablation-inductively coupled plasma-mass spectrometry and micro-X-ray fluorescence spectrometry for elemental imaging in Daphnia magna

Visualization of elemental distributions in thin sections of biological tissue is gaining importance in many disciplines of biological and medical research. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and scanning micro-X-ray fluorescence spectrometry (micro-XRF) are two widely used microanalytical techniques for elemental mapping. This article compares the capabilities of the two techniques for imaging the distribution of selected elements in the model organism Daphnia magna in terms of detection power and spatial resolution. Sections with a thickness of 10 and 20 μm of the fresh water crustacean Daphnia magna were subjected to LA-ICP-MS and micro-XRF analysis. The elemental distributions obtained for Ca, P, S and Zn allow element-to-tissue correlation. LA-ICP-MS and micro-XRF offer similar limits of detection for the elements Ca and P and thus, allow a cross-validation of the imaging results. LA-ICP-MS was particularly sensitive for determining Zn (LOD 20 μg g⁻¹, 15 μm spot size) in Daphnia magna, while the detection power of micro-XRF was insufficient in this context. However, LA-ICP-MS was inadequate for the measurement of the S distributions, which could be better visualized with micro-XRF (LOD 160 μg g⁻¹, 5 s live time). Both techniques are thus complementary in providing an exhaustive chemical profiling of tissue samples.     

Assessment of the acute toxicity of triclosan and methyl triclosan in wastewater based on the bioluminescence inhibition of Vibrio fischeri

In this work, the contributions of triclosan and its metabolite methyl triclosan to the overall acute toxicity of wastewater were studied using Vibrio fischeri. The protocol used in this paper involved various steps. First, the aquatic toxicities of triclosan and methyl triclosan were determined for standard substances, and the 50% effective concentrations (EC₅₀) were determined for these compounds. Second, the toxic responses to different mixtures of triclosan, methyl triclosan, and surfactants were studied in different water matrices, i.e., Milli-Q water, groundwater and wastewater, in order to evaluate (i) the antagonistic or synergistic effects, and (ii) the influence of the water matrices. Finally, chemical analysis was used in conjunction with the toxicity results in order to assess the aquatic toxicities of triclosan and its derivative in wastewaters. In this study, the toxicities of 45 real samples corresponding to the influents and effluents from eight wastewater treatment works (WWTW) were analyzed. Thirty-one samples were from a wastewater treatment plant (WWTP) equipped with two pilot-scale membrane bioreactors (MBR), and the influent and the effluent samples after various treatments were characterized via different chromatographic approaches, including solid-phase extraction (SPE), liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS), and SPE coupled to gas chromatography–mass spectrometry (GC–MS). The toxicity was determined by measuring the bioluminescence inhibition of Vibrio fischeri. In order to complete the study and to extrapolate the results to different WWTPs, the toxicity to V. fischeri of samples from seven more plants was analyzed, as were their triclosan and methyl triclosan concentrations. Good agreement was established between the overall toxicity values and concentrations of the biocides, indicating that triclosan is one of the major toxic organic pollutants currently found in domestic wastewaters.     

Employing a novel fiber optic detection system to monitor the dynamics of in situ lux bioreporter activity in porous media: system performance update

One of the major constraints to successful implementation of in situ bioremediation is our lack of understanding of how microbial activity is influenced by the physicochemical conditions in the subsurface environment. Our laboratory has successfully developed a novel fiber optic detection system that employs a lux bioreporter organism to non-invasively monitor real-time, in situ microbial activity in porous media. An evaluation of potential system limitations indicates that the system is not adversely affected by biofilm formation on the optical fiber tips or by bioluminescence attenuation in the porous medium employed. Additionally, the detection system effectively captures the dynamics of in situ bacterial gene expression during naphthalene catabolism under changing physicochemical conditions in saturated porous media. Therefore, this system enables laboratory-based studies of how physicochemical conditions in the subsurface influence microbial activity and will assist in improving: (1) our fundamental understanding of how transformation-related non-ideality, such as non-steady-state microbial activity, affects contaminant transport and fate; and (2) our ability to predict the efficacy of in situ bioremediation in dynamic, heterogeneous subsurface environments.     

Selective immobilization of Acinetobacter junii on the natural zeolitized tuff in municipal wastewater

The immobilization of desired bacteria onto material was usually performed in synthetic media. The aim of this study was to test the immobilization of phosphate (P)-accumulating bacteria Acinetobacter junii onto natural zeolitized tuff (NZ) in the raw or sterilized municipal wastewater containing the common bacteria Escherichia coli and Enterococcus faecalis and the performance of immobilized A. junii in the same type of wastewater. In the sterilized wastewater which contained the mixture of A. junii, E. coli and E. faecalis, the A. junii was selectively immobilized onto NZ in significantly higher numbers than E. coli and E. faecalis. The A. junii added in the form of bioparticles to the wastewater containing E. coli and E. faecalis, multiplied and removed P from wastewater. The P removal from wastewater was a function of biomass of P-accumulating bacteria and not the amount of NZ or bioparticles used. The performance of A. junii was significantly better in membrane filtered than in autoclaved wastewater. The experiments that were performed in raw non sterilized wastewater showed that A. junii can be successfully immobilized onto NZ in competition with natively present heterotrophic bacteria, retain its metabolic activity and successfully remove P from such water, which makes this technology feasible from biotechnological aspect.     

Synthesis, structural and larvicidal studies of some triorganotin 2-(p-chlorophenyl)-3-methylbutyrates

A series of triorganotin 2-(p-chlorophenyl)-3-methylbutyrates, (R₃SnO₂CCH(CH(CH₃)₂)C₆H₄Cl-4), where R = methyl, ethyl, n-propyl, n-butyl, phenyl and cyclo-hexyl, have been synthesized. Elemental analyses, Mössbauer, Infrared and NMR spectroscopies have been used to characterize their structures. Based on the spectroscopic results, all the complexes with the exception of the tricyclohexyl compound were found to be five-coordinated in the solid state while the tricyclohexyltin derivative was determined to be four-coordinated. Structural assignments based on spectroscopic data are supported by the crystallographic results of four of the triorganotin butyrates (trimethyl-, tri-n-propyl-, tri-n-butyl- and tricyclohexyltin 2-(p-chlorophenyl)-3-methylbutyrate). Multinuclear NMR spectroscopy studies indicated that all the complexes were tetrahedral in solution. Larvicidal activities of the complexes were evaluated against the 2nd instar stage of the Anopheles stephensi, Aedes aegypti and Culex pipiens quinquefasciatus mosquitoes. The toxicity data indicate that there does not appear to be any significant differences of the compounds towards the different mosquito species based on their averaged toxicity values. In addition, the toxicity of the triorganotin compounds towards the mosquito larvae was concluded to be dependent on both the compound and the species of mosquito larvae.     

Metal speciation of metallothionein in white sea catfish, Netuma barba, and pearl cichlid, Geophagus brasiliensis, by orthogonal liquid chromatography coupled to ICP-MS detection

Metal speciation analysis in MTs was carried out in two tropical fish species of Brazil, the freshwater fish pearl cichlid (Geophagus brasiliensis) and the marine fish white sea catfish (Netuma barba), that are presently used to monitor the effects of heavy metal pollution in aquatic ecosystems in Brazil. In order to obtain the MT fraction, liver cytosols from both fish species where subjected to size exclusion fractionation, monitoring on-line the metal signal (Cd, Cu and Zn) by ICP-MS while protein elution was followed by on-line UV detection. That MT fraction was then separated by anion-exchange (AE)-FPLC, whose optimal chromatographic conditions were optimized for the separation of the different hepatic MT isoforms existing in both fish species. Specific detection of separated metalloforms was carried out again by the hyphenation of the AE chromatographic system with the ICP-MS instrument. The analytical results showed that MTs of these fish species, unknown so far, exhibited unique characteristics in comparison with standard MTs and other fish liver MTs. In fact, MT isoforms of N. barba turned out to be very anionic, as indicated by their high retention in the Mono Q column and the strong ionic strength required to separate them. As for G. brasiliensis, cadmium was exclusively present in only one of the peaks of the MT isoforms showing a unique metal-binding behavior for MT in this fish species. The differences between the MTs among these species and the different association of metals in particular MT isoforms display the importance of the metal speciation analysis in these proteins prior to its use as bioindicators.     

Applications of particle-tracking analysis to the determination of size distributions and concentrations of nanoparticles in environmental, biological and food samples

The manufacture of nanoparticles (NPs) and nanomaterial-based products is rapidly increasing and their possible occurrence in environment, food or biological tissue is becoming of concern for ecological and human health. However, there is a lack of suitable methods to analyze and to characterize NPs in low concentrations in complex matrixes. We compare several particle-tracking methods using video microscopy and a new technique called nanoparticle-tracking analysis (NTA). Video microscopy has been widely applied to investigate particle movement in biological samples, micro-rheology, and velocity profiles in fluids, whilst NTA was devised for determination of size distributions and concentrations in liquid samples. We critically discuss the advantages and the limitations of NTA for such applications.     

Entrapment of Lentinus sajor-caju into Ca-alginate gel beads for removal of Cd(II) ions from aqueous solution: preparation and biosorption kinetics analysis

A white rot fungus species Lentinus sajor-caju biomass was entrapped into alginate gel via a liquid curing method in the presence of Ca(II) ions. The biosorption of cadmium(II) by the entrapped live and dead fungal biomass has been studied in a batch system. The heat-treatment process enhanced the biosorption capacity of the immobilized fungal biomass. The effect of initial cadmium concentration, pH and temperature on cadmium removal has been investigated. The maximum experimental biosorption capacities for entrapped live and dead fungal mycelia of L. sajur-caju were found to be 104.8±2.7 mg Cd(II) g⁻¹ and 123.5±4.3 mg Cd(II) g⁻¹, respectively. The kinetics of cadmium biosorption was fast, approximately 85% of biosorption taking place within 30 min. The biosorption equilibrium was well described by Langmuir and Freundlich adsorption isotherms. The change in the biosorption capacity with time is found to fit pseudo-second-order equations. Cadmium binding properties of entrapped fungal preparations have been determined applying the Ruzic equations. Since the biosorption capacities are relatively high for both entrapped live and dead forms, they could be considered as suitable biosorbents for the removal of cadmium in wastewater treatment systems. The biosorbents were reused in three consecutive adsorption/desorption cycles without significant loss in the biosorption capacity.     

Strategies for quantifying C(60) fullerenes in environmental and biological samples and implications for studies in environmental health and ecotoxicology

Fullerenes are sphere-like molecules with unique physico-chemical properties, which render them of particular interest in biomedical research, consumer products and industrial applications. Human and environmental exposure to fullerenes is not a new phenomenon, due to a long history of hydrocarbon-combustion sources, and will only increase in the future, as incorporation of fullerenes into consumer products becomes more widespread for use as anti-aging, anti-bacterial or anti-apoptotic agents.An essential step in the determination of biological effects of fullerenes (and their surface-functionalized derivatives) is establishment of exposure-assessment techniques. However, in ecotoxicological studies, quantification of fullerenes is performed infrequently because robust, uniformly applicable analytical approaches have yet to be identified, due to the wide variety of sample types. Moreover, the unique physico-chemistry of fullerenes in aqueous matrices requires reassessment of conventional analytical approaches, especially in more complex biological matrices (e.g., urine, blood, plasma, milk, and tissue).Here, we present a review of current analytical approaches for the quantification of fullerenes and propose a consensus approach for determination of these nanomaterials in a variety of environmental and biological matrices.     

New dimeric phenanthrenoids from the rhizomes of Juncus acutus. Structure determination and antialgal activity

In a study of the allelochemical interactions between the wetland plant Juncus acutus and microalgae some dimeric dihydrophenanthrenoids have been isolated. The structures have been determined on the basis of their spectroscopic properties and their phytotoxicity was evaluated on Selenastrum capricornutum.     

Distribution and accumulation of antimony in plants in the super-large Sb deposit areas, China

Antimony (Sb) distribution and accumulation in plants in Xikuangshan Sb deposit area, the only one super-large Sb deposit in the world, Hunan, China were investigated. Results show that soils were severely polluted with the average Sb concentrations up to 5949.20 mg kg^− 1. Sb widely occurred in 34 plants with various concentrations ranging from 3.92 mg kg⁻¹ to 143.69 mg kg^− 1, Equisetaceae family has the highest concentration (98.23 mg kg^− 1) while Dryopteridacea family has the lowest one (6.43 mg kg^− 1). H. ramosissima species of Equisetaceae family had the highest Sb average concentration of 98.23 mg kg^− 1 and P. vittata species of Pteridaceae family showed advantage of accumulating Sb from the contaminated environment (Biological Accumulation Coefficient, BAC = 0.08). Almost all species enriched Sb in their upground part such as shoot, leaf and flower (Biological Transfer Coefficient, BTC > 1), which may attribute to the high acropetal coefficient and Sb transformation from the atmosphere to the plants. P. phaseoloides and D. indicum showed predominantly accumulation of Sb in the upground part with BTC of 6.65 and 5.47, respectively.From the low bioavailable fraction in soils and weak relationship between total soil concentrations in soils and plants, it seems that the Sb bioavailability was limited and varied with different soil sites as well as plant species. Those observations would be significant to the phytoaccumulation and phytoremediation of plants and ecological and environmental risk assessment in Sb contaminated areas.     

Identification and quantification of 13 components in Angelica sinensis (Danggui) by gas chromatography-mass spectrometry coupled with pressurized liquid extraction

Angelica sinensis (Danggui in Chinese), a well-known traditional Chinese medicine, is also used as a health food product for women's care in Europe and America. Therefore, the demand for Danggui is enormous throughout the world. Due to the shortage of Angelica sinensis, Angelica acutiloba and Angelica gigas are commonly used as the substitutes of Danggui in the market of southeast Asia. However, the three common Angelica roots showed variation in their genetic and chemical composition. Up to date, it is thought that ferulic acid, ligustilide and other phthalides such as butylidenephthalide are the biologically active components of Danggui. In this paper, the contents of 13 compounds including ferulic acid, Z-ligustilide, E-ligustilide, Z-butylidenephthalide, E-butylidenephthalide, 3-butylphthalide, 3-butylidene-4-hydroxyphthalide, senkyunolide A, 6,7-epoxyligustilide, senkyunolide F, senkyunolide H, senkyunolide I, and 6,7-dihydroxyligustilide were determined or estimated by using gas chromatography-mass spectrometry (GC-MS) coupled with pressurized liquid extraction (PLE). The results showed that GC-MS coupled with PLE offered a simple, rapid and high sensitive method to analysis of components in Angelica root. And the contents of investigated compounds in Angelica sinensis, Angelica acutiloba and Angelica gigas, which are used as Danggui in China, Japan and Korea, respectively, were highly variant. It is thought that interaction of multiple chemical compounds contributes to the therapeutic effects of Chinese medicines. However, the overall clinical efficacy of these different Danggui has not been determined. Therefore, comparison of chemical components and pharmacological activities of different Angelica root is helpful to elucidate the mechanism of therapeutic effects of Danggui.     

Bacilosarcins A and B, novel bioactive isocoumarins with unusual heterocyclic cores from the marine-derived bacterium Bacillus subtilis

Two novel isocoumarins, bacilosarcins A (1) and B (2) were isolated from a culture broth of the marine-derived bacterium Bacillus subtilis TP-B0611. The structures and absolute configurations of 1 and 2 were determined on the basis of spectroscopic analyses and chemical conversions. Compound 1 possesses an unprecedented 3-oxa-6,9-diazabicyclo[3.3.1]nonane ring system while 2 has a 2-hydroxymorpholine moiety that is rare in nature. These compounds showed growth inhibition against barnyard millet.     

N,N′-Diisopropyl- and N,N′-dicyclohexylthiourea cadmium(II) complexes as precursors for the synthesis of CdS nanoparticles

Crystals of the cadmium(II) complexes of N,N-diisopropylthiourea and N,N-dicyclohexylthiourea were obtained and their X-ray single crystal structures determined. These complexes are air-stable, easy to prepare and inexpensive and decompose cleanly to give good quality crystalline CdS. The nanoparticles of CdS thus obtained showed quantum confinement effects in their optical spectra, with close to band-edge emission in luminescence experiments. The broad diffraction patterns observed are typical of nanodimensional particles. The variation of concentration of precursor-to-HDA ratio change the isolated materials from spheres to rod-shaped. TEM images showed agglomerates of needle-like plate of particles.     

Biosynthesis of anisotropic gold nanoparticles using Maduca longifolia extract and their potential in infrared absorption

Metal nanoparticles, in general, and gold nanoparticles, in particular, are very attractive because of their size- and shape-dependent properties. Biosynthesis of anisotropic gold nanoparticles using aqueous extract of Madhuca longifolia and their potential as IR blockers has been demonstrated. The tyrosine residue was identified as the active functional group for gold ion reduction. These gold nanoparticles were characterized by of UV-Vis spectrophotometer, FTIR, TEM and HrTEM. The presence of proteins was identified by FTIR, SDS-PAGE, UV-Vis and fluorescence spectroscopy. The micrograph revealed the formation of anisotropic gold nanoaprticles. The biologically synthesized gold nanotriangles can be easily coated in the glass windows which are highly efficient in absorbing IR radiations.