Green synthesis of Copper oxide nanoparticles decorated with graphene oxide for anticancer activity and catalytic applications

Nanotechnology is an embryonic field that grips countless impacts on the drug delivery system. Nanoparticles as haulers increase the capability of target-specific drug delivery to many folds hence are used in the treatment of dreadful diseases such as cancer, diabetes, etc. This boom has aimed at, to synthesize Copper oxide nanoparticles (CuO-NPs) using Acalypha Indica leaf extract and then incorporated with graphene oxide (GO) to form GO-CuO nanocomposites. Secondly, to sightsee the photocatalytic activity of CuO-NPs and GO-CuO nanocomposites towards the decolorization of methylene blue-dye and to test its activity against HCT-116 Human colon cancer cell lines. Synthesized nanocomposites were characterized using FTIR, UV–vis, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray Photoelectron Spectroscopy (XPS) and transmission electron microscopy (TEM) analysis. The photocatalytic studies revealed that synthesized nanocomposites have the efficiency to degrade methylene blue dye by 83.20% and cytotoxic activity was found to be 70% against HCT-116 Human colon cancer cell lines at 100 μg/ml. GO-CuO nanocomposites have appreciable activity towards cancer cell lines and photocatalytic activity when compared to nanoparticles as such.     

Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles

The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol–gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol–gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. Furthermore, obviously even the crystal structure can differ from the corresponding bulk material like in the case of MnO nanoparticles. In the second part of the paper we present original results regarding the synthesis of dilute magnetic semiconductor TiO₂ nanoparticles doped with cobalt and iron. The structural characterization as well as the magnetic properties with special attention to the doping efficiency is discussed.     

Synthesis and characterization of thermo-responsive copolymeric nanoparticles of poly(methyl methacrylate-co-N-vinylcaprolactam)

Copolymeric nanoparticles of methyl methacrylate (MMA) and N-vinylcaprolactam (VCL) were prepared through free radical polymerization using hydrogen peroxide and l-ascorbic acid as a redox initiator in o/w microemulsion containing sodium dodecyl sulphate (SDS). The copolymers were characterized by FTIR and gel permeation chromatography (GPC) and composition of copolymer was determined by ¹H NMR spectroscopy. Reactivity ratio was determined by linear least square and non-linear least square methods. The morphology and particle size distribution of copolymer latexes was determined through transmission electron microscopy (TEM) and dynamic light scattering (DLS). Copolymers were of less than 50 nm size with spherical morphology and latexes were stable for more than 6 months. Phase transition temperature measured through UV-vis spectrometry, for the synthesized copolymer indicates their potential use in biosensors and targeted drug delivery system. Cytotoxicity of nanoparticles was determined by MTT assay on B16F10 melanoma cell lines. Cell viability data shows the IC₅₀ values of copolymeric nanoparticles to be in the range of 0.01-0.1 mg/mL.     

Surfactant-free synthesis of sub-stoichiometry tungsten oxide nanoparticles and their use as anode buffer layers in organic solar cells

A surfactant-free synthesis of small-sized tungsten trioxide is presented. Nanoparticles with an average size of 4.6 ± 1.5 nm are prepared via hot-injection techniques in ethanol. Due to the reducing properties of ethanol, a sub-stoichiometry composition WO_3-x (x∼0.4) is obtained. The partial reduction of W^+VI to W^+V becomes visible in the bluish color of suspensions and powder samples and in optical spectroscopy (UV-Vis). The nanoparticles are further characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDXS) and infrared spectroscopy (FT-IR). Due to their small size, their high colloidal stability and the absence of surfactants, layers from the as-prepared WO_3-x nanoparticles are ideally suited to form anode buffer layers in organic solar cells. Exemplary solar cells show good power conversion efficiency of 6.3%.     

Green synthesis of silver nanoparticles by using eugenol and evaluation of antimicrobial potential

The importance of green synthesis was revealed with advantages such as: eliminating the use of expensive chemicals; consume less energy; and generate environmentally benign products. With this aim, silver nanoparticles (AgNPs) were synthesized by using isolated eugenol from clove extract. Its antimicrobial potential was determined on three different microorganisms. Clove was extracted and eugenol was isolated from this extract. Green synthesis was performed and an anti‐microbial study was performed. All extraction and isolation analyses were performed by high‐performance liquid chromatography (HPLC); identification and confirmation were achieved using liquid chromatography–mass spectrometry (LC–MS); and scanning electron microscopy was used for characterization. Both HPLC and LC–MS analyses showed that eugenol obtained purely synthesized AgNPs and 20‐25‐nm‐sized and homogeneous shaped particles seen in images. The antimicrobial effects of AgNPs at eight concentrations were determinated against Staphylococcus aureus, Escherichia coli and Candida albicans, and maximum inhibition zone diameters were found as 2.6 cm, 2.4 cm and 1.5 cm, respectively. The results of the antimicrobial study showed that eugenol as a biological material brought higher antimicrobial effect to AgNPs in comparison to the other materials found in the literature.     

Phase diagrams of non-ionic microemulsions containing reducing agents and metal salts as bases for the synthesis of bimetallic nanoparticles

Phase diagrams of microemulsions containing metal salt(s) and reducing agent, respectively, were studied in detail. The microemulsions were based on non-ionic surfactants, namely pure tetraethyleneglycol monododecylether, C₁₂E₄, and technical grade Brij30. We studied the influence of the metal salts H₂PtCl₆, Pb(NO₃)₂, Bi(NO₃)₃, H₂PtCl₆ + Pb(NO₃)₂ (1:1 mixture), and H₂PtCl₆ + Bi(NO₃)₃ (1:1 mixture) as well as of the reducing agent NaBH₄ on the location of the phase boundaries. The focus was on the water emulsification failure boundary (wefb) where the aqueous phase forms spherical droplets. The temperature shifts of the wefb, which were caused by the presence of the salt(s), are directly related with the shift of the clouding points of the corresponding oil-free systems. The location of the wefb is affected in a complex manner by the pH (the lower the pH the higher the temperature at which the wefb occurred), the ionic strength and by specific salting-in or salting-out effects of the electrolyte ions. The desired overlap of the wefb of the microemulsions containing the metal salt(s) and the reducing agent, respectively, could be achieved by adding NaOH to the C₁₂E₄-based microemulsions and by titrating 1-octanol to the Brij30-based microemulsions, respectively.     

Nonaqueous synthesis of metal oxide nanoparticles:Review and indium oxide as case study for the dependence of particle morphology on precursors and solvents

Nonaqueous solution routes to metal oxide nanoparticles are a valuable alternative to the well-known aqueous sol-gel processes, offering advantages such as high crystallinity at low temperatures, robust synthesis parameters and ability to control the crystal growth without the use of surfactants. In the first part of the review, we give an overview of the various nonaqueous routes to metal oxides, their surface functionalization and their assembly into well-defined nanostructures. However, we will strongly focus on surfactant-free processes developed in our group. Within the various reaction systems such as metal halides—benzyl alcohol, metal alkoxides—benzyl alcohol, metal alkoxides—ketones, metal acetylacetonates—benzyl alcohol and metal acetylacetonates—benzylamine we will discuss representative examples in order to show the versatility of this approach. The careful characterization of the organic species in the final reaction mixtures provides information about possible condensation mechanisms. Depending on the system several reaction pathways have been postulated: (i) elimination of organic ethers as result of condensation between two metal alkoxide precursors; (ii) C–C bond formation between the alkoxy ligand of the metal alkoxide precursor and the solvent benzyl alcohol under formation of a metal hydroxyl species, which can undergo further condensation; (iii) ketimine and aldol-like condensation steps, which in the metal acetylacetonate systems are preceded by a solvolysis of the precursor, involving C–C bond cleavage. In the second part of the paper we will focus on the synthesis of indium oxide nanoparticles using different precursors and solvents. Indium oxide represents an instructive example how the oxide precursors and the solvents influence the particle morphology. These findings make it possible to tailor particle size and shape of a particular metal oxide by the appropriate choice of the reaction system.     

Green synthesis,characterization and photocatalytic application of silver nanoparticles synthesized by various plant extracts

Recently, the discharge of effluent containing dyes and other chemicals into river, lakes, and land has become a serious problem which increases the pollution level drastically. The dyes in the effluent are very difficult to be removed by conventional water treatment methods. Thus, there is a great need for more advanced methods that are cost-effective and more efficient. In this study, silver nano particles (AgNps) were synthesized by green method using extracts of onion (O), tomato (T), acacia catechu (C) alone, and mixed COT extracts. The reduction and formation of AgNps and its ions have been characterized by using several techniques, Ultra visible spectroscopy (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM)-energy dispersive X-ray spectrometer (EDX), Fourier transmission infrared spectroscopy (FTIR), and dynamic light scattering (DLS). These techniques revealed that the particle sizes of synthesized AgNps in all the extracts were ranged in between 5 and 100 nm with a crystalline nature. The synthesized AgNps were used as catalysts for the degradation of three different types of dyes, methyl orange (MO), methyl red (MR), and congo red (CR) in the liquid state. The excellent catalytic application of all the synthesized AgNps on the degradation of the studied dyes was confirmed via UV–visible results by studying the reduction in the absorbance maxima value within a very short interval of time. COT synthesized products were found to achieve the best performance for all dyes degradation among all products.     

Simultaneous determination of metal ions, amino acids, and other small biogenic molecules in human serum by capillary zone electrophoresis with transient isotachophoretic preconcentration

CE with indirect UV detection was used for the simultaneous determination of lithium, magnesium, calcium, creatinine, carnitine, and a number of amino acids in human serum. The target analytes, positively charged under acidic electrolyte conditions, were separated with positive separation voltage polarity using 10 mM 4-methylbenzylamine, 4.5 mM citric acid, 25% (v/v) methanol at pH 4.05 as background electrolyte providing optimal separation. When analyzing real samples, however, some peaks were broadened due to essentially destacking conditions. In order to maintain the separation efficiency and also enhance the detection sensitivity, transient isotachophoresis (tITP) sample stacking was applied and yielded theoretical plate numbers in the range from 160,000 (arginine) to 350,000 (creatinine). The limit of detection values with tITP preconcentration were 0.11-0.26 mg L(-1) for metal cations, 1.0 mg L(-1) for creatinine, and 1.3-3.9 mg L(-1) for histidine, lysine, arginine, and ornithine. The method precision for peak areas was from 0.4 to 5.0% relative standard deviation using the matrix sodium as internal standard. The accuracy of the developed tITP-CZE system was verified by consistent results for Li+, Mg2+, Ca2+, and creatinine obtained on analyzing two serum certified reference materials. The only sample preparation required was ultrafiltration and acidification (to release protein-bound alkaline earths), and working ranges for individual analytes corresponded well to clinical concentration ranges.     

Green synthesis of biologically active transition metal nanoparticles containing novel Schiff base via catalyst free hydrothermal reaction: Structural,biological and morphology study

Novel cobalt, nickel and copper complexes were synthesized by regular reflux method and nano sized Co(II), Ni(II) and Cu(II) metal complexes were synthesized by a facile hydrothermal method using green solvent at various temperatures without the addition of any capping agent. The structural characterization was done by magnetic susceptibility, molar conductance, elemental analysis, thermal analysis, FT‐IR, ¹H NMR, ¹³C NMR, ESI mass, UV–Visible analysis. The morphology and size of the nano metal complexes were determined using FE‐Scanning electron microscopy, powder X‐ray diffraction data and atomic force microscopic techniques. All the spectral and analytical results reveal 1:2 metal to ligand ratios having [ML₂(H₂O)₂] stoichiometry, here M=Co(II), Ni(II) and Cu(II), L=deprotonated ligand. The non‐electrolytic nature of the compound was confirmed by molar conductance experiment. The synthesized Schiff base and its metal complexes (7, 8 and 9) were tested for their biological activity. All the tested compounds exhibit decent anticancer and DNA cleavage activity and copper complex shows better activity results than other tested compounds.     

Green synthesis of copper oxide nanoparticles CuO NPs from Eucalyptus Globoulus leaf extract: Adsorption and design of experiments

The study is concerned with synthesizing copper oxide nanoparticles with leaf extract Eucalyptus Globoulus. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) revealed that the green synthesized copper oxide nanoparticles are spherical and have a mean particle size of 88 nm, with a negative zeta potential of ?16.9 mV. The XRD graph showed the crystalline and monoclinic phases of CuO nanoparticles. The average crystalline size around 85.80 nm was observed by the Debye–Scherrer formula. The adsorption characteristics of the nano-adsorbents were investigated using methyl orange, and the adsorption efficiency at room temperature attained 95 mg/g. Copper oxide nanoparticles (CuO NPs) adsorb methyl orange dye most effectively at pH 4.5 when the dye is applied in quantities of 0.04 g/50 mL. Box–Behnken design (BBD) in response surface methodology (RSM) was used to optimize various process parameters, such as pH solution (X₁: 2 – 11), adsorbing dose (X₂: 0.01 – 0.08 g/L), [MO] dye concentration (X₃: 10 – 80 mg/L). Overall, the adjusted coefficient of determination (R²) value of 0.99 demonstrated that the used model was quite appropriate, and the chosen RSM was effective in optimization the decolorization conditions of MO.     

Green synthesis of silver nanoparticles by bloom forming marine microalgae Trichodesmium erythraeum and its applications in antioxidant,drug-resistant bacteria,and cytotoxicity activity

In the present study, we developed an eco-friendly method of stable silver nanoparticles (AgNPs) production using the aqueous extract of Trichodesmium erythraeum. The biosynthesized AgNPs were characterized using UV–Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Energy-Dispersive X-ray (EDX), and X-ray diffraction (XRD). The results affirmed that synthesized AgNPs were crystalline in nature, cubical in shape, and the average size of T. erythraeum silver nanoparticles (TENPs) was 26.5 nm. The antioxidant potential of synthesized AgNPs (500 µg/ml) was 77.01 ± 0.17% in DPPH, 67.5 ± 0.22% in Deoxy-ribose, 52.77 ± 0.42% in ABTS and 88.12 ± 0.26% in nitric oxide radical scavenging assays. The antibacterial results showed excellent inhibition against the clinical strains (Staphylococcus aureus and Proteus mirabilis) and drug-resistant bacterial strains such as E. coli (Amikacin^R), S. aureus (Tetracycline^R) and S. pneumoniae (Penicillin^R). The maximum anti-proliferative effect of TENPs was seen using 50 µg concentration against He La and MCF-7 cell lines, and IC₅₀ values were 25.0 ± 0.50 µg/ml and 30.0 ± 0.50 µg/ml, respectively, at 24 h.