Biosynthesis of antibacterial gold nanoparticles using brown alga, Stoechospermum marginatum (kützing)

Toxicity of silver and gold nanoparticles on marine microalgae

The increased use of nanomaterials in several novel industrial applications during the last decade has led to a rise in concerns about the potential toxic effects of released engineered nanoparticles (NPs) into the environment, as their potential toxicity to aquatic organisms is just beginning to be recognised. Toxicity of metallic nanoparticles to aquatic organisms, including microalgae, seems to be related to their physical and chemical properties, as well as their behaviour in the aquatic media where processes of dissolution, aggregation and agglomeration can occur. Although the production of these particles has increased considerably in recent years, data on their toxicity on microalgae, especially those belonging to marine or estuarine environments remain scarce and scattered. The literature shows a wide variation of results on toxicity, mainly due to the different methodology used in bioassays involving microalgae. These can range for up to EC50 data, in the case of AgNPs, representing five orders of magnitude. The importance of initial cellular density is also addressed in the text, as well as the need for keeping test conditions as close as possible to environmental conditions, in order to increase their environmental relevance. This review focuses on the fate and toxicity of silver, gold, and gold-silver alloy nanoparticles on microalgae, as key organisms in aquatic ecosystems. It is prompted by their increased production and use, and taking into account that oceans and estuaries are the final sink for those NPs. The design of bioassays and further research in the field of microalgae nanoecotoxicology is discussed, with a brief survey on newly developed technology of green (algae mediated) production of Ag, Au and Ag-Au bimetallic NPs, as well as some final considerations about future research on this field.

Organic-inorganic hybrid nanoparticles for bacterial inhibition: synthesis and characterization of doped and undoped ONPs with Ag/Au NPs

Organic nanoparticles (ONPs) of lipoic acid and its doped derivatives ONPs/Ag and ONPs/Au were prepared and characterized by UV-Visible, EDS, and TEM analysis. The antibacterial properties of the ONPs ONPs/Ag and ONPs/Au were tested against bacterial strains (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Salmonella typhi). Minimal Inhibitory Concentration (MIC) and bacterial growth inhibition tests show that ONPs/Ag are more effective in limiting bacterial growth than other NPs, particularly, for Gram positive than for Gram-negative ones. The order of bacterial cell growth inhibition was ONPs/Ag > ONPs > ONPs/Au. The morphology of the cell membrane for the treated bacteria was analyzed by SEM. The nature of bond formation of LA with Ag or Au was analyzed by molecular orbital and density of state (DOS) using DFT.

Molecular characterization of a Xylanase-producing fungus isolated from fouled soil

Xylanase (EC 3. 2. 1. 8), hydrolyzes xylo-oligosaccharides into D-xylose and required for complete hydrolysis of native cellulose and biomass conversion. It has broad range of applications in the pulp and paper, pharmaceutical and Agri-food industries. Fifty fungal species were isolated from the fouled soil around an oil refinery and screened for the production of xylanase enzyme by enrichment culture techniques. The isolated fungal strain was identified as Hypocrea lixii SS1 based on the results of biochemical tests and 18s rRNA sequencing. The phylogenetic tree was constructed using the MEGA 5 software. Further, Hypocrea lixii SS1 was tested for the ability to utilize the sunflower oil sludge (waste from the oil industry) as the sole carbon source for xylanase production. The growth characteristics of Hypocrea lixii SS1 were also studied and maximum growth was found on the 7^th day of incubation. The fungus showed a remarkable xylanase production of 38.9 U/mL. Xylanase was purified using a combination of 0–50% NH₄SO₂ precipitation, DEAE-sepharose and Sephacryl S-200 chromatography. Single peak obtained in RP-HPLC confirms the purity of xylanase. Further the enzyme produced was affirmed as xylanase with its molecular weight (29 kDa) using SDS-PAGE.

Biosynthesis of gold nanoparticles using Sargassum swartzii and its cytotoxicity effect on HeLa cells

In this investigation, biological synthesis of gold nanoparticles (AuNPs) using Sargassum swartzii and its cytotoxicity against human cervical carcinoma (HeLa) cells is reported. The biological synthesis involved the reduction of chloroauric acid led to the formation of AuNPs within 5min at 60°C and the formation of AuNPs was confirmed using UV-vis spectrophotometer. The AuNPs were stable; spherical in shape with well-defined dimensions, and the average size of the particle is 35nm. A zeta potential value of -27.6mV revealed synthesized AuNPs were highly stable. The synthesized AuNPs exhibited a dose-dependent cytotoxicity against human cervical carcinoma (HeLa) cells. Furthermore, induction of apoptosis was measured by DAPI (4',6-Diamidino-2-phenylindole dihydrochloride) staining.

Green synthesis of pullulan stabilized gold nanoparticles for cancer targeted drug delivery

The aim of this study was to synthesize green chemistry based gold nanoparticles using liver specific biopolymer and to develop a liver cancer targeted drug delivery system with enhanced efficacy and minimal side effects. Pullulan stabilized gold nanoparticles (PAuNPs) were coupled with 5-Fluorouracil (5-Fu) and folic acid (Fa) which could be used as a tool for targeted drug delivery and imaging of cancer. The toxicity of 5-Fu, 5-Fu adsorbed gold nanoparticles (5-Fu@AuNPs), Fa-coupled 5-Fu adsorbed gold nanoparticles (5-Fu@AuNPs-Fa), was studied using zebrafish embryo as an in vivo model. The in vitro cytotoxicity of free 5-Fu, 5-Fu@AuNPs, 5-Fu@AuNPs-Fa against HepG2 cells was studied and found that the amount of 5-Fu required to achieve 50% of growth of inhibition (Ic50) was much lower in 5-Fu@AuNP-Fa than in free 5-Fu, 5-Fu@AuNPs. The in vivo biodistribution of PAuNPs showed that higher amount of gold had been accumulated in liver (54.42±5.96 μg) than in other organs.

Spectroscopic investigations, antimicrobial, and cytotoxic activity of green synthesized gold nanoparticles

The gold nanoparticles (AuNPs) were synthesized by using naturally available Punica Granatum fruit extract as reducing and stabilizing agent. The biosynthesized AuNPs was characterized by using UV-Vis, fluorescence, high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric (TGA) analysis. The surface plasmon resonance (SPR) band at 585nm confirmed the reduction of auric chloride to AuNPs. The crystalline nature of the biosynthesized AuNPs was confirmed from the HRTEM images, XRD and selected area electron diffraction (SAED) pattern. The HRTEM images showed the mixture of triangular and spherical-like AuNPs having size between 5 and 20nm. The weight loss of the AuNPs was measured by TGA as a function of temperature under a controlled atmosphere. The biomolecules are responsible for the reduction of AuCl4(-) ions and the formation of stable AuNPs which was confirmed by FTIR measurement. The synthesized AuNPs showed an excellent antibacterial activity against Candida albicans (ATCC 90028), Aspergillus flavus (ATCC 10124), Staphylococcus aureus (ATCC 25175), Salmonella typhi (ATCC 14028) and Vibrio cholerae (ATCC 14033). The minimum inhibitory concentration (MIC) of AuNPs was recorded against various microorganisms. Further, the synthesized AuNPs shows an excellent cytotoxic result against HeLa cancer cell lines at different concentrations.

Marine algae-mediated synthesis of gold nanoparticles using a novel Ecklonia cava

In the present study, we report rapid biological synthesis of gold nanoparticles (Au NPs) using a novel marine brown alga Ecklonia cava (Family: Lessoniaceae) by the reduction of chloroauric acid. The formation of Au NPs reaction was complete within 1 min at 80 °C and physiochemically characterized with different analytical techniques. FTIR spectroscopy revealed that Au NPs were functionalized with biomolecules that have primary amine group, hydroxyl group and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face-centered cubic structure of Au NPs. Microscopy results showed that these Au NPs are formed with shapes like spherical and triangular with an average size of 30 ± 0.25 nm. Synthesized Au NPs showed good antimicrobial and biocompatibility with human keratinocyte cell line. Thus, physiochemical characteristic results suggest that Au NPs will have promising biomedical applications in different area such as drug delivery, tissue engineering, biosensor, etc.

Effect of biologically synthesized gold nanoparticles on alloxan-induced diabetic rats-an in vivo approach

Development of novel antidiabetic agents using various organic compounds and biomolecules has been in practice for a long time. Recently, nanomaterials are also being used in antidiabetic studies for their unique properties such as small size, biocompatibility and ability to penetrate cell membrane for carrying drugs. Herein, in vivo antidiabetic activity of gold nanoparticles (AuNPs) synthesized using the antidiabetic potent plant Gymnema sylvestre R. Br on wistar albino rats has been evaluated. The formation of AuNPs and their morphology were confirmed using spectroscopic and microscopic analyses, respectively. The treatment of AuNPs has shown significant reduction in blood glucose level on diabetic rats. AuNPs were also tested for its anti-inflammatory effect by estimating the serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and high-sensitive C-reactive protein (CRP).

Phytofabrication of gold nanoparticles assisted by leaves of Suaeda monoica and its free radical scavenging property

Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. An eco-friendly synthesis of inorganic nanoparticle is a fast growing research in the limb of nanotechnology. In the present study, it is reported that Suaeda monoica leaf mediated synthesis of gold nanoparticles by the reduction of gold ions. The formation of gold nanoparticle was confirmed by color changes from turbid brown to deep purple violet color and a characteristic peak at 535 nm. The morphology and structure of synthesized gold nanoparticles were characterized on Scanning Electron Microscopy (SEM) equipped with a Thermo EDAX attachment, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), (FT-IR), Dynamic Light Scattering (DLS) which reveals that the Au nanoparticles are spherical and the average particle size is 12.96 nm. Crystalline nature of the nanoparticles is confirmed from the XRD pattern. FTIR spectrum indicates that the biomolecules of carboxyl, amine and hydroxyl functional groups involved in the reduction of gold nanoparticles. The biosynthesized gold nanoparticles displayed considerable antioxidant capacity.

Synthesis and characterization of silver and gold nanoparticles using aqueous extract of seaweed, Turbinaria conoides, and their antimicrofouling activity

Silver and gold nanoparticles were synthesized using an aqueous extract of the seaweed Turbinaria conoides and their antibiofilm activity against marine biofilm forming bacteria is reported here. The UV-Vis spectra showed the characteristics SPR absorption band for Ag NPs at 421 and for Au NPs at 538 nm. Further, the synthesized nanoparticles were characterized using FT-IR, XRD, FESEM, EDX, and HRTEM analysis. Spherical and triangular nanostructures of the Ag and Au nanoparticles were observed between the size ranges of 2–17 nm and 2–19 nm, respectively. The synthesized Ag NPs are efficient in controlling the bacterial biofilm formation; however, Au NPs did not show any remarkable antibiofilm activity. The maximum zone of inhibition was recorded against E. coli (17.6 ± 0.42 mm), followed by Salmonella sp., S. liquefaciens, and A. hydrophila. The macrotube dilution method inferred the MIC (20–40 µL mL⁻¹) and MBC (40–60 µL mL⁻¹) of Ag NPs. The CLSM images clearly showed the weak adherence and disintegrating biofilm formation of marine biofilm bacterial strains treated with Ag NPs. The Artemia cytotoxicity assay recorded the LC₅₀ value of 88.914 ± 5.04 µL mL⁻¹. Thus the present study proved the efficiency of Ag NPs as a potent antimicrofouling agent and became the future perspective for the possible usage in the biofouling related issues in the aquaculture installations and other marine systems.

Algae Mediated Green Fabrication of Silver Nanoparticles and Examination of Its Antifungal Activity against Clinical Pathogens

Algae extract has the great efficiency to synthesize the silver nanoparticles as a green route. Brown seaweed mediates the synthesis of silver nanomaterials using extract of Sargassum longifolium. For the improved production of silver nanomaterials, some kinetic studies such as time incubation and pH were studied in this work. 10 mL of algal extract was added into the 1 mM AgNO3 aqueous solution. The pH and reaction time range were changed and the absorbance was taken for the characterization of the nanoparticles at various time intervals, and the high pH level shows the increased absorbance due to the increased nanoparticles synthesis. The synthesized silver nanoparticles were characterized by Scanning Electron Microscope (SEM) showing that the shape of the material is spherical, and X-Ray Diffraction value obtained from range of (1 1 1) confirmed synthesized silver nanoparticles in crystalline nature. TEM measurement shows spherical shape of nanoparticles. The Fourier Transmittance Infrared spectrum (FT-IR) confirms the presence of biocomponent in the algae extract which was responsible for the nanoparticles synthesis. The effect of the algal mediated silver nanoparticles against the pathogenic fungi Aspergillus fumigatus, Candida albicans, and Fusarium sp. S. longifolium mediated synthesized silver nanoparticles shows cheap and single step synthesis process and it has high activity against fungus. This green process gives the greater potential biomedical applications of silver nanoparticles.

Cardioprotective potential of biobased gold nanoparticles

In the present investigation, the cardioprotective nature of proanthocyanidin (PAC)-synthesized gold nanoparticles (AuNPs) is addressed in detail. There was a rapid reduction of gold metal ions by PAC and the new-genre AuNPs exhibited remarkable in vitro stability both in biological and chemical solutions. Transmission electron microscopy (TEM) indicated that the newly formed nanoparticles ranged in size from 17 to 29 nm (∼24 nm). MTT assay carried out with peripheral blood mononuclear cells demonstrated the non-toxic nature of AuNPs. PAC-synthesized AuNPs showed cardioprotective action in isoproterenol-induced myocardial injury at a lowest dosage (9 mg kg(-1)). Cardiac marker enzymes and antioxidant parameters in serum and heart tissue were also measured.

Biosynthesis of Silver Nanoparticles Using Brown Marine Macroalga, Sargassum Muticum Aqueous Extract

Biological synthesis of nanoparticles is a relatively new emerging field of nanotechnology which has economic and eco-friendly benefits over chemical and physical processes of synthesis. In the present work, for the first time, the brown marine algae Sargassum muticum (S. muticum) aqueous extract was used as a reducing agent for the synthesis of nanostructure silver particles (Ag-NPs). Structural, morphological and optical properties of the synthesized nanoparticles have been characterized systematically by using FTIR, XRD, TEM and UV-Vis spectroscopy. The formation of Ag-NPs was confirmed through the presence of an intense absorption peak at 420 nm using a UV-visible spectrophotometer. A TEM image showed that the particles are spherical in shape with size ranging from 5 to 15 nm. The nanoparticles were crystalline in nature. This was confirmed by the XRD pattern. From the FTIR results, it can be seen that the reduction has mostly been carried out by sulphated polysaccharides present in S. muticum.

Functionalization of gold nanoparticles as antidiabetic nanomaterial

In the present investigation, functionalization of gold nanoparticles synthesized using propanoic acid 2-(3-acetoxy-4,4,14-trimethylandrost-8-en-17-yl) (PAT) an active biocomponent isolated from Cassia auriculata is studied in detail. On reaction of PAT with aqueous HAuCl4, rapid formation of stable gold nanoparticles was achieved. Formation of gold nanoparticles was confirmed by UV-vis spectroscopy, XRD, GC-MS,FTIR, TEM and SEM with EDAX. Gold nanoparticles mostly were monodisperse, spherical in shape and ranged in size 12-41 nm. Gold nanoparticles synthesised using PAT was administered to alloxan (150 mg/kg body weight) induced diabetic male albino rats at different doses (0.25, 0.5, 0.75 and 1.0mg/kg body weight) for 28 days. Plasma glucose level, cholesterol and triglyceride were significantly (p<0.001) reduced in experimental animals treated with gold nanoparticles at dosage of 0.5mg/kg body weight and plasma insulin increased significantly. The newly genre green gold nanoparticles exhibit remarkable protein tyrosine phosphatase 1B inhibitory activity.

Stoichiometrically controlled production of bimetallic Gold-Silver alloy colloids using micro-alga cultures

This paper reports the production of well-defined, highly stable Ag-Au alloy nanoparticles (NPs) using living cells of Chlamydomonas reinhardtii, with the composition of the bimetallic alloys being solely determined by the stoichiometric ratio in which the metal salts were added to the cultures. The NPs exhibited a single, well-defined surface plasmon resonance (SPR) band confirming that they were made of a homogeneous population of bimetallic alloys. Particle creation by the cells occurred in three stages: (1) internalization of the noble metals by the cells and their reduction resulting in the formation of the NPs; (2) entrapment of the NPs in the extracellular matrix (ECM) surrounding the cells, where they are colloidally stabilized; and (3) release of the NPs from the ECM to the culture medium. We also investigated the effect of the addition of the metals salts on cell viability and the impact on characteristics of the NPs formed. When silver was added to the cultures, cell viability was decreased and this resulted in a ~30nm red shift on the SPR band due to changes in the surrounding environment into which the NPs were released. The same observations (in SPR and cell viability) was made when gold was added to a final concentration of 2 × 10(-4)M, but not when the concentration was equal to 10(-4)M, where cell viability was high and the red shift was negligible.

Facile synthesis of silver chloride nanoparticles using marine alga and its antibacterial efficacy

Exploitation of advancements in antimicrobial agent synthesis assisted by nanomaterials has received considerable attention in the recent years. Based on this, an eco-friendly approach for the synthesis of silver chloride nanoparticles (AgClNPs) using aqueous extract of Sargassum plagiophyllum is emphasized. UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FESEM) were used to characterize the formation of AgClNPs. X-ray diffraction (XRD) patterns clearly illustrate the presence of AgClNPs. The synthesized AgClNPs were tested for its antibacterial activity and it was found to cause considerable amount of deterioration to bacterial cells, when examined using electron microscope and cell viability analysis.

Protocol for development of various plants leaves extract in single-pot synthesis of metal nanoparticles

This article is aimed to extend a simple protocol for preparation of various plant leaves extract and their application to green synthesis of the metallic nanoparticles. Five plant leaves extract showed mild reduction and stabilization ability for silver and gold nanoparticles (AgNPs and AuNPs) at room temperature. The particle size range varied from 25 to 42 nm and 21 to 47 nm for AgNPs and AuNPs, respectively. Plant leaves extract-mediated nanoparticles were characterized to confirm the shape, size, crystallinity, and content using different spectroscopic investigations. Differences in stability of nanoparticles at different pH were also measured by zeta potential.