Effects of a butterfly scale microstructure on the iridescent color observed at different angles

Multilayer thin-film structures in butterfly wing scales produce a colorful iridescence from reflected sunlight. Because of optical phenomena, changes in the angle of incidence of light and the viewing angle of an observer result in shifts in the color of butterfly wings. Colors ranging from green to purple, which are due to nonplanar specular reflection, can be observed on Papilio blumei iridescent scales. This refers to a phenomenon in which the curved surface patterns in the thin-film structure cause the specular component of the reflected light to be directed at various angles while affecting the spectral reflectivity at the same time by changing the optical path length through the structure. We determined the spectral reflectivities of P. blumei iridescent scales numerically by using models of a butterfly scale microstructure and experimentally by using a microscale-reflectance spectrometer. The numerical models accurately predict the shifts in spectral reflectivity observed experimentally.     

Investigation of the morphological cell structures and their optical significances of Aeshna cyanea

The transparent wing of the dragonfly Aeshna cyanea has been investigated using scanning electron microscopy (SEM), optical microscopy (OPM), energy‐dispersive X‐ray spectroscopy (EDS) and reflectance spectroscopy. Four cells (D1–D4) were studied and classified according to their general morphology. The OPM depicted the vein‐joint characterised by the distribution of resilin. EDS technique showed common elements such as carbon, oxygen, and chlorine. SEM analysis revealed thin membranes reinforced with a network of hallow veins. Spikes and round shape of microstructures were identified. The roughness of the pruinosity was estimated, which indicates the shape and curvature of the microstructures that essentially play a significant role in the optical response observed. The study can be essential to design and improve micro‐air vehicles.Inspec keywords: bio‐optics, optical microscopy, biomembranes, light reflection, X‐ray chemical analysis, scanning electron microscopy, crystal microstructureOther keywords: transparent wing, EDS technique, SEM analysis, morphological cell structures, optical microscopy, dragonfly Aeshna cyanea, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, reflectance spectroscopy, vein‐joint characterization, resilin distribution, carbon, oxygen, chlorine, thin membrane reinforced hallow vein network, microstructure spikes, microstructure round shape, micro‐air vehicles     

Facile synthesis of anisotropic gold nanoparticles and its synergistic effect on breast cancer cell lines

Gold nanoparticles (AuNPs) possess colourful light‐scattering properties due to different composition, size and shape. Their unique physical, optical and chemical properties coupled with advantages, have increased the scope of anisotropic AuNPs in various fields. This study reports a green methodology developed for the synthesis of anisotropic AuNPs. The aqueous extracts of Alternanthera sessilis (PGK), Portulaca oleracea (PAK) and Sterculia foetida (SF) with gold ions produced violet, purple and pink coloured AuNPs, respectively, under sonication and room temperature methods revealing the formation of different shapes of AuNPs. The results of TEM analysis of AuNPs confirmed the formation of triangular plate AuNPs of the size 35 nm for PAK extract. Spherical‐shaped AuNPs (10–20 nm) were obtained using an extract of PGK. SF extract produced rod, hexagon, pentagon‐shaped AuNPs and nanorice gold particles. The cell viability studies of the PGK, PAK and SF‐mediated AuNPs on MCF‐7 cell lines by MTT assay revealed the cytotoxic activity of AuNPs to depend on the size, shape and the nature of capping agents. The synthesised AuNPs significantly inhibited the growth of cancer cells (MCF‐7) in a concentration‐dependent manner. The size and shape of these anisotropic AuNPs also reveal its potency to be used as sensors, catalysis, photothermal and therapeutic agents.Inspec keywords: toxicology, gold, transmission electron microscopy, catalysis, nanofabrication, biomedical materials, nanomedicine, particle size, cellular biophysics, nanoparticles, cancer, biological organsOther keywords: Au, size 10.0 nm to 20.0 nm, temperature 293.0 K to 298.0 K, size 35.0 nm, TEM analysis, Sterculia foetida, Portulaca oleracea, Alternanthera sessilis, chemical properties, colourful light‐scattering properties, anisotropic AuNP, triangular plate AuNP, spherical‐shaped AuNP, SF‐mediated AuNP, cancer cells, MCF‐7 cell lines, cell viability, nanorice gold particles, gold ions, optical properties, breast cancer cell lines, anisotropic gold nanoparticles     

Extracellular biosynthesis of biocompatible CdSe quantum dots

An extracellular biosynthesis method has been developed to prepare cadmium selenide (CdSe) quantum dots (QDs) with strong fluorescence emission by incubating cheap Cd and Se inorganic salts with Escherichia coli (E.coli) bacteria. Ultraviolet–visible absorption spectra, photoluminescence (PL) spectra, and high‐resolution transmission electron microscopy analysis showed that the biosynthesised CdSe QDs have an average size of 3.1 nm, the excellent optical properties with fluorescence emission around 494 nm, and the good crystallinity. It was found that addition of 80 mg of mercaptosuccinic acid resulted in the formation of CdSe QDs with highest PL intensity. Furthermore, Fourier‐transform infrared spectra of as‐synthesised CdSe QDs confirmed the presence of a surface protein capping layer. The biosynthesised CdSe QDs were incorporated into the yeast cells as illustrated by laser confocal scanning microscopy images, showing a great potential in bio‐imaging and bio‐labelling application.Inspec keywords: microorganisms, molecular biophysics, fluorescence, visible spectra, nanofabrication, nanobiotechnology, proteins, cellular biophysics, nanostructured materials, wide band gap semiconductors, cadmium compounds, semiconductor quantum dots, II‐VI semiconductors, transmission electron microscopy, photoluminescence, optical microscopy, ultraviolet spectra, Fourier transform infrared spectra, biological techniques, semiconductor growthOther keywords: biocompatible CdSe quantum dots, extracellular biosynthesis method, cadmium selenide quantum dots, high‐resolution transmission electron microscopy analysis, biosynthesised CdSe QDs, Fourier‐transform infrared spectra, Escherichia coli, ultraviolet‐visible absorption spectra, PL intensity, fluorescence emission, photoluminescence spectra, optical properties, surface protein capping layer, laser confocal scanning microscopy images, bioimaging, biolabelling application, yeast cells, f mercaptosuccinic acid, CdSe     

Relative larvicidal property of common oxide nanostructures against Culex quinquefasciatus

Common oxide nanostructures such as silicon‐di‐oxide, magnesium‐oxide, zinc‐oxide, and copper‐oxide (CuO) having useful functional and bioactive properties have been synthesised and characterised. All these nanostructures have been found to be larvicidal towards Culex quinquefasciatus mosquito especially against lower instars in comparison with higher instars in 48 h. Only, CuO is larvicidal against late instar stages after 48 h. Moreover, CuO is larvicidal against first instar stages after 24 h (LC₅₀ 157 mg/l). However, none of these nanostructures are pupicidal. Post mortality larval morphology was found to be distorted under bright field microscopy and scanning electron microscopy images of affected larval surface appeared to be rough and uneven. Fluorescent images showed that nanostructures infiltrated inside visceral organs of larvae. Nanostructures also caused tissue oxidative stress in larvae. These results indicate that above stated oxide nanostructures are effective larvicidal agents against early instar stages of Culex larvae.Inspec keywords: biodegradable materials, oxidation, optical microscopy, fluorescence, cellular biophysics, biological tissues, diseases, scanning electron microscopy, toxicology, biological techniquesOther keywords: late instar stages, bright field microscopy, scanning electron microscopy images, tissue oxidative stress, oxide nanostructures, silicon‐dioxide, magnesium‐oxide, zinc‐oxide, copper‐oxide, functional properties, bioactive properties, larvicidal property, larvicidal agents, Culex quinquefasciatus mosquito, Culex larvae     

Function of blue iridescence in tropical understorey plants

The blue colouration seen in the leaves of Selaginella willdenowii is shown to be iridescent. Transmission electron microscopy studies confirm the presence of a layered lamellar structure of the upper cuticle of iridescent leaves. Modelling of these multi-layer structures suggests that they are responsible for the blue iridescence, confirming the link between the observed lamellae and the recorded optical properties. Comparison of blue and green leaves from the same plant indicates that the loss of the blue iridescence corresponds to a loss of the multi-layer structure. The results reported here do not support the idea that iridescence in plants acts to enhance light capture of photosynthetically important wavelengths. The reflectance of light in the range 600–700 nm is very similar for both iridescent and non-iridescent leaves. However, owing to the occurrence of blue colouration in a wide variety of shade dwelling plants it is probable that this iridescence has some adaptive benefit. Possible adaptive advantages of the blue iridescence in these plants are discussed.     

Electrochemical assessment of the interaction of microbial living cells and carbon nanomaterials

This work considers the effects of various carbon nanomaterials and fibres on bioelectrocatalytic and respiratory activity of bacterial cells during the oxidation of ethanol in the presence of an electron transport mediator. Gluconobacter oxydans sbsp. industrius VKM B‐1280 cells were immobilised on the surfaces of graphite electrodes and had an adsorption contact with a nanomaterial (multi‐walled carbon nanotubes, thermally expanded graphite, highly oriented pyrolytic graphite, graphene oxide, reduced graphene oxide). The electrochemical parameters of the electrodes (the polarisation curves, the value of generated current at the introduction of substrate, the impedance characteristics) were measured in two‐electrode configuration. Modification by multi‐walled carbon nanotubes led to the increase of microbial fuel cell (MFC) electric power by 26%. The charge transfer resistance of modified electrodes was 47% lower than unmodified ones. Thermally expanded and pyrolytic graphites had a slight negative effect on the electrochemical properties of modified electrodes. The respiratory activity of bacterial cells did not change in the presence of nanomaterials. The data can be used in the development of microbial biosensors and MFC electrodes based on Gluconobacter cells.Inspec keywords: nanofabrication, catalysis, microorganisms, adsorption, charge exchange, microbial fuel cells, electrochemical electrodes, graphite, graphene, oxidation, multi‐wall carbon nanotubes, cellular biophysicsOther keywords: reduced graphene oxide, electrochemical parameters, two‐electrode configuration, multiwalled carbon nanotubes, microbial fuel cell, respiratory activity, bacterial cells, microbial biosensors, MFC electrodes, microbial living cells, electron transport mediator, graphite electrodes, adsorption contact, highly oriented pyrolytic graphite, Gluconobacter oxydans sbsp. industrius VKM B‐1280 cells, polarisation curves, bioelectrocatalytic activity, ethanol, thermally expanded graphite, charge transfer resistance, C     

Optical properties of the scales of Morpho rhetenor butterflies: theoretical and experimental investigation of the back-scattering of light in the visible spectrum.

A study of the optical properties of the largely periodic microstructure occurring on the wings of the iridescent tropical butterfly Morpho rhetenor and responsible for its structural colouration is reported. An extensive measurement of the back-scattering of visible light from butterfly scales was performed for various angles of incidence. Efficient low-pass filter behaviour was observed for all angles of incidence and polarizations, with near-complete transmission at wavelengths above the threshold of 550 nm. The angular spread of the back-scattered light was found to be organized in lobes with total extinction of the specular reflection for all conditions of incidence. Retro-reflector behaviour was also observed for angles of incidence of 30 degrees and above. Additionally, the role of periodic geometrical features found in the microstructure for the generation of its spectral response was analysed theoretically. Using finite-difference time-domain and near-field to far-field transformation techniques, the back-scattering of visible light by models was computed numerically and the relevance of geometrical features for the production of structural colour and diffraction was demonstrated.     

Multifaceted activities of plant gum synthesised platinum nanoparticles: catalytic,peroxidase, PCR enhancing and antioxidant activities

A single pot, green method for platinum nanoparticles (Pt NP) production was devised with gum ghatti (Anogeissus latifolia). Analytical tools: ultraviolet–visible (UV‐vis), dynamic light scattering, zeta potential, transmission electron microscope, X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy were employed. Wide continuous UV‐vis absorption and black solution colouration proved Pt NP formation. Face‐centred cubic crystalline structure of NP was evidenced from XRD. NPs formed were nearly spherical with a mean particle size of 3 nm. NP demonstrated a myriad of properties including catalytic, peroxidase, polymerase chain reaction (PCR) enhancing and antioxidant activities. Catalytic action of NP was probed via NaBH₄ reduction of arsenazo‐III dye. NP displayed considerable peroxidase activity via catalysis of 3, 3′, 5, 5′‐tetramethylbenzidine oxidation by H₂ O₂. NP showed exceptional stability towards varying pH (3–11), temperature (25–100°C), salt concentration (0–100 mM) and storage time duration (0–12 months). In comparison with horse radish peroxidase, its applicability as an artificial peroxidase is advantageous. NP caused a two‐fold enhancement in PCR yield at 0.4 nM. Also showed significant 1′, 1′ diphenyl picryl‐hydrazyle scavenging (80.1%) at 15 µg/mL. Author envisages that the biogenic Pt NP can be used in a range of biological and environmental applications.Inspec keywords: nanofabrication, ultraviolet spectra, catalysis, molecular biophysics, enzymes, dyes, platinum, electrokinetic effects, transmission electron microscopy, particle size, X‐ray diffraction, visible spectra, pH, nanomedicine, nanoparticles, biochemistry, light scattering, scanning electron microscopy, Fourier transform infrared spectra, reduction (chemical), oxidationOther keywords: antioxidant activities, catalytic action, salt concentration, artificial peroxidase, two‐fold enhancement, PCR yield, multifaceted activities, plant gum synthesised platinum nanoparticles, gum ghatti, anogeissus latifolia, analytical characterisation tools, dynamic light scattering, zeta potential, X‐ray diffraction, XRD, black solution colouration, Pt NP formation, face‐centred cubic crystalline structure, peroxidase activity, ultraviolet‐visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, particle size, catalytic activity, PCR enhancing activity, single pot green method, wide continuous UV‐visible absorption, polymerase chain reaction enhancing activity, arsenazo‐III, azo dye decolourisation, 3, 3′, 5, 5′‐tetramethylbenzidine oxidation, pH, environmental conditions, 1′,1′ diphenyl picryl‐hydrazyle scavenging, time 0.0 month to 12.0 month, temperature 25.0 degC to 100.0 degC, Pt     

Lobelia trigona Roxb ‐based nanomedicine with enhanced biological applications: in vitro and in vivo approach

This is the first study to report the green synthesis of Lobelia trigona Roxb‐ mediated silver nanoparticles (LTAgNPs). The optical and structural properties of the synthesised LTAgNPs were analysed using ultraviolet–visible spectroscopy, scanning electron microscopy, Fourier transform infrared, dynamic light scattering and energy dispersive X‐ray. LTAgNps were evaluated for their anti‐bacterial and anti‐fungal properties against 18 pathogens and exhibited significant inhibition against all the strains tested. LTAgNPs had potential scavenging effects on the DPPH, ^• OH, O₂ ^•− free radical scavenging assays and reducing power assay. LTAgNps possess strong anti‐cancer activity against five human cancer cell lines (A549, MCF‐7, MDA‐MB‐231, HeLa and KB) in a dose‐dependent manner. The antiproliferative, anti‐inflammatory and genotoxicity effects of LTAgNPs were further confirmed by the lactate dehydrogenase release assay, nitric oxide inhibitory assay and comet assay. Furthermore, the incision, excision and burn wound‐healing activity of formulated LTAgNPs ointment was assessed in rats. All the wounds had significant healing in groups treated with LTAgNPs ointment compared to the groups treated with the commonly prescribed ointment (Silverex^TM). This study shows and suggests that the previously unreported LTAgNPs could be used as a nanomedicine with significant biological applications.Inspec keywords: molecular biophysics, biomedical materials, scanning electron microscopy, biochemistry, cancer, microorganisms, silver, cellular biophysics, nanofabrication, wounds, nanomedicine, ultraviolet spectra, toxicology, antibacterial activity, light scattering, nanoparticles, enzymes, visible spectra, Fourier transform infrared spectraOther keywords: Lobelia trigona Roxb‐based nanomedicine, biological applications, Lobelia trigona Roxb‐mediated silver nanoparticles, optical properties, structural properties, ultraviolet‐visible spectroscopy, dynamic light scattering, antibacterial properties, antifungal properties, scavenging effects, free radical scavenging, power assay, anticancer activity, antiinflammatory effects, genotoxicity effects, lactate dehydrogenase release assay, nitric oxide inhibitory assay, excision, burn wound‐healing activity, formulated LTAgNPs ointment, in vivo approach, in vitro approach, scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X‐ray analysis, pathogens, strains, A549 human cancer cell lines, MCF‐7 human cancer cell lines, MDA‐MB‐231 human cancer cell lines, HeLa human cancer cell lines, antiproliferative effects, comet assay, Ag     

Exaggeration and suppression of iridescence: the evolution of two-dimensional butterfly structural colours.

Many butterfly species possess 'structural' colour, where colour is due to optical microstructures found in the wing scales. A number of such structures have been identified in butterfly scales, including three variations on a simple multi-layer structure. In this study, we optically characterize examples of all three types of multi-layer structure, as found in 10 species. The optical mechanism of the suppression and exaggeration of the angle-dependent optical properties (iridescence) of these structures is described. In addition, we consider the phylogeny of the butterflies, and are thus able to relate the optical properties of the structures to their evolutionary development. By applying two different types of analysis, the mechanism of adaptation is addressed. A simple parsimony analysis, in which all evolutionary changes are given an equal weighting, suggests convergent evolution of one structure. A Dollo parsimony analysis, in which the evolutionary 'cost' of losing a structure is less than that of gaining it, implies that 'latent' structures can be reused.     

Method development for optimised green synthesis of gold nanoparticles from Millettia pinnata and their activity in non‐small cell lung cancer cell lines

Green synthesis of gold nanoparticles (GNPs) has received substantial attention, because nanoparticles are produced in an eco‐friendly way using biomolecules present in plant extracts in a single step reaction. This research article highlights GNPs obtained using shade‐dried leaf extracts of Millettia pinnata (L.) with aqueous auric chloride (HAuCl₄) at ambient temperature. In the present study, GNPs with average particle size 37 nm in size were fabricated. Furthermore, the synthesis method to obtain stable and monodispersed GNPs was advanced by optimising enzyme concentration 100 μg/ml, pH 5.4, substrate concentration 0.45 mM and 12 h time of reaction. The confirmation of GNPs formation and characterisation was followed by UV‐vis‐absorption spectroscopy, dynamic light scattering (DLS), and zeta potential (ZP) for the analysis of shape, size, and stability, respectively. TEM images and powder XRD revealed the GNPs synthesis of spherical‐shaped nanoparticles in the face‐centred cubic arrangement. Cytotoxicity of GNPs was studied against A549 lung cancer cells with IC₅₀ 14.76 μg/ml and found lower as compared to doxorubicin IC₅₀ 11.23 μg/ml but significant enough to be used as a vehicle GNPs produced using green source can be used as significant therapeutic agents and drug delivery carriers.Inspec keywords: nanomedicine, molecular biophysics, cancer, electrokinetic effects, pH, transmission electron microscopy, toxicology, gold, cellular biophysics, X‐ray diffraction, lung, biomedical materials, nanofabrication, nanoparticles, particle size, enzymes, visible spectra, ultraviolet spectra, light scattering, biochemistryOther keywords: method development, optimised green synthesis, gold nanoparticles, millettia pinnata, nonsmall cell lung cancer cell lines, plant extracts, single step reaction, shade‐dried leaf extracts, aqueous auric chloride, synthesis method, stable GNPs, monodispersed GNPs, spherical‐shaped nanoparticles, A549 lung cancer cells, green source, particle size, enzyme concentration, substrate concentration, biomolecules, reaction time, UV‐visible‐absorption spectroscopy, dynamic light scattering, zeta potential, TEM images, powder XRD, face‐centred cubic arrangement, cytotoxicity, pH, therapeutic agents, drug delivery carriers, time 12.0 hour, Au     

Antibacterial activity of carbon nanoparticles isolated from chimney soot

Carbon nanoparticles (CNPs) are isolated from chimney soot and characterised by various tools such as X‐ray diffraction, scanning electron microscopy, transmission electron microscopy and ultraviolet–visible spectroscopy. The X‐ray diffraction studies confirm the presence of C₆₀ nanoparticles in the isolated sample. The thermal properties of the prepared CNPs are recorded using thermogravimetric analysis and differential thermal analysis. The analysis of the antibacterial activity of the synthesised CNPs against selected Gram‐positive and Gram‐negative bacterial strains is also investigated. The systematic study confirms that CNPs collected from chimney soot exhibit good antibacterial potency against Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, and Proteus mirabilis.Inspec keywords: ultraviolet spectra, scanning electron microscopy, visible spectra, differential thermal analysis, thermal analysis, antibacterial activity, nanoparticles, X‐ray diffraction, nanofabrication, transmission electron microscopy, carbonOther keywords: chimney soot, transmission electron microscopy, ultraviolet–visible spectroscopy, thermal properties, thermogravimetric analysis, differential thermal analysis, antibacterial activity, carbon nanoparticles, X‐ray diffraction study, gram‐positive bacterial strains, gram‐negative bacterial strains, antibacterial potency, scanning electron microscopy, C₆₀      

Bio‐inspired synthesis of silver nanoparticles from leaf extracts of Cleistanthus collinus (Roxb.): its potential antibacterial and anticancer activities

In this investigation, the biological synthesis method was adopted to synthesise silver nanoparticles (AgNPs) by using the leaf extracts of Cleistanthus collinus (C. collinus). This plant has traditionally been used to remove the harmful pest from the agriculture field. Leaf extract of C. collinus was used as bioreductant on the precursor solvent of AgNO₃. The synthesised AgNPs were characterised by spectroscopic method such as UV–vis spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, dynamic light scattering and microscopic method by field‐emission scanning electron microscopy analysis. The AgNPs were studied for both antibacterial and antifungal activities and found to exhibit potential antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa. The anticancer activity of AgNPs was screened against A‐431 osteosarcoma cell line by [3‐(4, 5‐dimetheylthiazol‐2)‐2, 5 diphenyl tetrazolium bromide] assay and the IC₅₀ value was found to be 91.05 ± 1.53 μg/ml. This trend of eco‐friendly stable synthesis of AgNPs could prove a better substitute for the chemical methods and offer greater opportunity to use these nanosilvers in agricultural and biomedical sectors.Inspec keywords: bio‐inspired materials, silver, nanoparticles, nanomedicine, antibacterial activity, cancer, biomedical materials, microorganisms, nanofabrication, attenuated total reflection, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, light scattering, scanning electron microscopy, field emission electron microscopy, cellular biophysicsOther keywords: bio‐inspired synthesis, silver nanoparticles, Cleistanthus collinus, antibacterial activity, anticancer activity, leaf extracts, biological synthesis method, bioreductant, precursor solvent, UV‐visible spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, dynamic light scattering, field‐emission scanning electron microscopy, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, A‐431 osteosarcoma cell line, 3‐(4, 5‐dimetheylthiazol‐2)‐2,5 diphenyl tetrazolium bromide assay, eco‐friendly stable synthesis, Ag     

Fabrication of antibacterial sponge cleaner using gold nanoclusters

From the dinner table to the office, many surfaces contain bacteria and the threat to human health. In this work, cost‐effective antimicrobial foams were developed by the adsorption of lysozyme protected gold nanoclusters (AuNCs) in sponges. Antibacterial activities of the prepared antibacterial AuNCs were evaluated using typical Gram‐negative bacteria (Escherichia coli) and Gram‐positive bacteria (Staphylococcus aureus). The antibacterial foams were further fabricated by the absorption of the positively charged AuNCs in the negatively charged sponges. The inhibitions of bacteria on random surfaces, such as mobile phones, tables, doorknobs, and cabinet handles, were exhibited by cleaning them with the antibacterial foams.Inspec keywords: molecular biophysics, gold, microorganisms, nanomedicine, nanofabrication, adsorption, antibacterial activity, enzymes, metal clusters, nanostructured materials, porous materials, foamsOther keywords: antibacterial sponge cleaner, human health, cost‐effective antimicrobial foams, antibacterial activity, Gram‐negative bacteria, Escherichia coli, Gram‐positive bacteria, Staphylococcus aureus, random surfaces, antibacterial gold nanoclusters, adsorption, positively charged gold nanoclusters, negatively charged sponges, lysozyme protected gold nanoclusters, Au     

Sunlight induced biosynthesis of silver nanoparticle from the bark extract of Amentotaxus assamica D.K. Ferguson and its antibacterial activity against Escherichia coli and Staphylococcus aureus

Green synthesis of nanoparticles has gained importance due to its eco‐friendly, low toxicity and cost effective nature. This study deals with the biosynthesis of silver nanoparticles (AgNPs) from the bark extract of Amentotaxus assamica. The AgNPs have been synthesised by reducing the silver ions into stable AgNPs using the bark extract of Amentotaxus assamica under the influence of sunlight irradiation. The characterisation of the biosynthesised AgNPs was carried out by UV–vis spectroscopy, X‐ray diffraction analysis (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and energy dispersive X‐ray analysis. The UV–vis spectrum showed a broad peak at 472 nm. Also, the XRD confirmed the crystalline structure of the AgNPs. Moreover, the SEM analysis revealed that the biosynthesised AgNPs were spherical in shape. Also, dynamic light scattering techniques were used to evaluate the size distribution profile of the biosynthesised AgNPs. Furthermore, the biosynthesised AgNPs showed a prominent inhibitory effect against both Escherichia coli (MTCC 111) and Staphylococcus aureus (MTCC 97). Thus the biosynthesis of AgNPs from the bark extract of Amentotaxus assamica is found to eco‐friendly way of producing AgNPs compared to chemical method.Inspec keywords: X‐ray chemical analysis, microorganisms, transmission electron microscopy, nanoparticles, toxicology, scanning electron microscopy, ultraviolet spectra, particle size, Fourier transform spectra, X‐ray diffraction, antibacterial activity, visible spectra, infrared spectra, nanomedicine, silverOther keywords: stable AgNP, biosynthesised AgNP, SEM analysis, sunlight irradiation, silver ions, silver nanoparticle, amentotaxus assamica, biosynthesis, escherichia coli     

Structural and optical investigation on the wings of Idea malabarica (Moore, 1877)

The nanostructures on the wings of Idea malabarica (Moore, 1877) were analysed using scanning electron microscopy, energy dispersive X‐ray spectroscopy, atomic force microscopy, Fourier transform‐infrared spectroscopy, and reflectance measurements. The chemical and morphological analyses revealed the chitin‐based intricate nanostructures. The influence of the nanostructures on the wetting characteristics of the wing was investigated using optical imaging. Applying the Maxwell‐Garnet approximation to the porosities within the nanostructures, the refractive indices, which relate the reflectance response, were estimated. It was concluded that the colour seen on the wings of the Idea malabarica originate from the nanostructural configurations of the chitin‐based structures and the embedded pigment.Inspec keywords: scanning electron microscopy, X‐ray chemical analysis, atomic force microscopy, Fourier transform infrared spectra, reflectivity, wetting, porosity, refractive index, nanostructured materials, nanobiotechnology, bio‐opticsOther keywords: Idea malabarica wings, scanning electron microscopy, energy dispersive X‐ray spectroscopy, atomic force microscopy, Fourier transform‐infrared spectroscopy, reflectance measurements, chitin‐based intricate nanostructures, wetting, Maxwell‐Garnet approximation, porosity, refractive indices     

Tree gum stabilised selenium nanoparticles: characterisation and antioxidant activity

Selenium nanoparticles (Se NPs) were synthesised using sodium borohydride as a reductant and gum kondagogu as a stabiliser. Plant gum serves as a renewable, non‐toxic, non‐immunogenic, biopolymer based feedstock. Role of gum on synthesis and mean particle size was studied using ultraviolet‐visible spectroscopy and dynamic light scattering. NP generation was visualised with orange red colouration and NPs exhibited a surface plasmon resonance peak at 250 nm. Formed NPs were amorphous, polydisperse and spherical. NPs showed a bimodal distribution, size varied from 44.4 to 200 nm and mean particle size was 105.6 nm. NP solution exhibited a zeta potential of −39.9 mV, confirming the superior stability. In comparison to ionic Se, the gum capped Se NPs exhibited superior 1, 1‐diphenyl‐2‐picrylhydrazyle and 2, 2‐azinobis‐(3‐ethylbenzthinzoline‐6‐sulphonic acid) radial scavenging activities of 73.2 and 92.2%, respectively, at 25 µg/ml. Antibacterial potential of NPs was checked with well diffusion assay. NPs exhibited growth inhibition activity against Gram‐positive bacteria only. Bacillus subtilis and Micrococcus luteus showed respective inhibition zones of 6.3 and 8.6 mm at 12 µg. Thus, the present study demonstrates the applicability of tree gum stabilised Se NPs as a potent antioxidant nutrition supplement at a much lower dose, in comparison with ionic Se.Inspec keywords: light scattering, microorganisms, particle size, nanoparticles, antibacterial activity, selenium, surface plasmon resonance, nanofabrication, visible spectra, organic compounds, reduction (chemical), electrokinetic effects, ultraviolet spectra, renewable materials, sodium compoundsOther keywords: mean particle size, selenium nanoparticles, sodium borohydride reductant, kondagogu gum stabiliser, biopolymer‐based feedstock, renewable material, ultraviolet–visible spectroscopy, orange red colouration, dynamic light scattering technique, zeta potential value, surface plasmon resonance method, antibacterial potential, well‐diffusion assay, Bacillus subtilis, Micrococcus luteus, antioxidant nutrition supplement, bacterial growth inhibition activity, 2,2‐azinobis‐(3‐ethylbenzthinzoline‐6‐sulphonic acid), 1,1 diphenyl picryl hydrazyle, size 105.6 nm, size 6.3 mm, size 8.6 mm, size 44.4 nm to 200.0 nm, Se, NaBH₄      

Antibacterial and anticancer activity of biosynthesised CuO nanoparticles

The present investigation aims for the synthesis of copper oxide nanoparticles (CuO NPs) using Nilgirianthus ciliatus plant extract. The obtained CuO NPs were characterised by X‐ray diffraction, Fourier transform infrared spectrum, ultraviolet–visible spectroscopy, photoluminescence, scanning electron microscopy and transmission electron microscopy analysis. Significant bacterial activity was manifested by CuO nanoparticles against both Gram‐positive (Staphylococcus aureus and Staphylococcus mutans) and Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The synthesised CuO NPs have good cytotoxicity against both human breast cancer cell line (MCF‐7) and lung cancer cell line (A549) with minimum cytotoxic effect on normal L929 (fibroblast) cell lines.Inspec keywords: microorganisms, ultraviolet spectra, nanomedicine, transmission electron microscopy, visible spectra, cellular biophysics, antibacterial activity, nanoparticles, X‐ray diffraction, lung, copper compounds, cancer, toxicology, biomedical materials, scanning electron microscopy, photoluminescence, Fourier transform infrared spectraOther keywords: antibacterial activity, anticancer activity, biosynthesised CuO nanoparticles, copper oxide nanoparticles, Nilgirianthus ciliatus plant, X‐ray diffraction, infrared spectrum, ultraviolet–visible spectroscopy, transmission electron microscopy analysis, bacterial activity, Gram‐negative bacteria, synthesised CuO NPs, human breast cancer cell line, Staphylococcus aureus, Staphylococcus mutans, CuO     

Cytotoxicity properties of functionalised carbon nanotubes on pathogenic bacteria

Nanobiotechnology is a promising field concerned with the using of engineered nanomaterials, which leads to the improvement of new human remedial against pathogenic bacteria modalities. In this work, silver nanoparticles (AgNPs) were prepared by an easy, cheap and low‐cost electro‐chemical method. The AgNPs were then loaded successfully on to multi‐walled carbon nanotubes (MWCNTs) using a modified chemical reaction process. The AgNPs on the MWCNTs were well spread and evenly distributed on the surfaces of the long nanotubes with well‐graphitised walls as examined by high‐resolution transmission electron microscopy. X‐ray diffraction and transmission electron microscopy were used for sample characterisation. Good dispersion of AgNPs was obtained on the surface of MWCNTs, resulting in an efficient reactivity of the carbon nanotubes surfaces. Finally, the antibacterial activity of AgNPs/MWCNTs hybrid was evaluated against two pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus exhibited excellent activity.Inspec keywords: nanocomposites, X‐ray diffraction, nanofabrication, nanoparticles, transmission electron microscopy, toxicology, silver, antibacterial activity, microorganisms, nanomedicine, multi‐wall carbon nanotubes, electrochemistryOther keywords: engineered nanomaterials, human remedial, pathogenic bacteria modalities, silver nanoparticles, multiwalled carbon nanotubes, modified chemical reaction process, well‐graphitised walls, high‐resolution transmission electron microscopy, cytotoxicity properties, functionalised carbon nanotubes, carbon nanotube surfaces, nanobiotechnology, low‐cost electrochemical method, AgNP‐MWCNT hybrid, X‐ray diffraction, antibacterial activity, Pseudomonas aeruginosa, Staphylococcus aureus, Ag‐C