Gold nanorod production by cyanobacteria—a green chemistry approach
TL;DR: In this paper, the first intracellular bioconversion of auric ion (Au3+) to gold nanorod by the cyanobacterium Nostoc ellipsosporum has been observed for the first time in laboratory condition.
Abstract: Intracellular bioconversion of auric ion (Au3+) to gold nanorod (Au0) by the cyanobacterium Nostoc ellipsosporum has been observed for the first time in laboratory condition. The nanorods were produced within the cell after exposing the healthy growing filaments to 15 mg L−1 gold (III) solution (pH 4.5) for 48 h at 20°C. The gold nanoparticles were extracted with sodium citrate solution and were subjected to UV–Visible spectroscopy. The characteristic surface-multiple plasmon bands at 560, 610, and 670 nm were observed. The nature and size of the particles were determined by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and zeta potential studies. The nanorod size ranged from 137 to 209 nm in length and 33 to 69 nm in diameter. DLS study revealed the average hydrodynamic size as 435 nm and XRD study indicated the reduction of Au3+ to Au0. Methods of extraction and preservation of gold nanorod particles have also been studied.
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TL;DR: The present paper reviews the information available on algae-mediated biosynthesis of various NPs, their characterization and applications in different domains and concludes that algae are an appealing platform for the production of diverse NMs.
247 citations
TL;DR: Recent advances in the adaptation of noble metal nanomaterials and their biomedical applications in therapeutics, diagnostics and sensing are highlighted.
217 citations
TL;DR: Two well-known wet chemical techniques, namely chemical reduction and sol-gel methods, used to produce various types of nanocrystalline powders, metal oxides, and hybrid organic-inorganic nanomaterials have presented.
179 citations
TL;DR: In this paper, the authors present a review of the role of algae in the production of nanomaterials, focusing on the diversity of algal strains exploited in the booming field of nanobiotechnology and green chemistry, the various methodologies through which these diverse organisms are used, and the variety of fabricated materials composed of noble metals, oxides and chalcogenides.
154 citations
TL;DR: This review article is focused on recent progress on the utilization of algae of various classes, viz., Cyanophyceae, ChlorophyCEae, Phaeophyceiae, RhodophyceAE, etc. for the synthesis of nanoparticles, their characterization and the possible mechanisms involved.
Abstract: As nanotechnology is expanding to several commercial fields, there is a need of ecofriendly and energy-efficient methods for the synthesis of nanoparticles. Algae have been discovered to reduce metal ions and subsequently for the biosynthesis of nanoparticles. Since algae-mediated biosynthesis of nanoparticles is an ecofriendly, economical, high-yielding, expeditious and energy-efficient method, a large number of studies have been published in the last few years. This review article therefore is focused on recent progress on the utilization of algae of various classes, viz., Cyanophyceae, Chlorophyceae, Phaeophyceae, Rhodophyceae, etc. for the synthesis of nanoparticles, their characterization and the possible mechanisms involved.
153 citations
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TL;DR: It is found that, after exposure to continuous red laser at 800 nm, malignant cells require about half the laser energy to be photothermally destroyed than the nonmalignant cells, so both efficient cancer cell diagnostics and selective photothermal therapy are realized at the same time.
Abstract: Due to strong electric fields at the surface, the absorption and scattering of electromagnetic radiation by noble metal nanoparticles are strongly enhanced. These unique properties provide the potential of designing novel optically active reagents for simultaneous molecular imaging and photothermal cancer therapy. It is desirable to use agents that are active in the near-infrared (NIR) region of the radiation spectrum to minimize the light extinction by intrinsic chromophores in native tissue. Gold nanorods with suitable aspect ratios (length divided by width) can absorb and scatter strongly in the NIR region (650−900 nm). In the present work, we provide an in vitro demonstration of gold nanorods as novel contrast agents for both molecular imaging and photothermal cancer therapy. Nanorods are synthesized and conjugated to anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies and incubated in cell cultures with a nonmalignant epithelial cell line (HaCat) and two malignant oral epithelial ...
5,047 citations
"Gold nanorod production by cyanobac..." refers background in this paper
...They also act as hyperthermia agents and destroy tumors and cancer cells (Huang et al. 2006; Hauck et al. 2008)....
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TL;DR: PEG-modified gold nanoparticles showed a nearly neutral surface, and had little cytotoxicity in vitro, following intravenous injection into mice, whereas most of gold was detected in the liver in the case of original gold nanorods stabilized with CTAB.
1,133 citations
"Gold nanorod production by cyanobac..." refers background in this paper
...As a result, chemically synthesized gold nanorods may develop undesirable functional aberration in a target cell and several attempts have been made to minimize the use of CTAB in gold nanorod synthesis (Niidome et al. 2006)....
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TL;DR: In this paper, the authors showed that symmetry breaking in fcc metallic structures to produce anisotropic nanoparticles is based on an intrinsic structural mechanism (twinning) that is subsequently modulated extrinsically during growth in solution by specific adsorption of AuI-surfactant complexes on the side faces/edges of the isometric penta-twinned crystals and which is responsible for the preferential growth along the common [110] axis.
Abstract: Gold nanorods were prepared via a seed-mediated sequential growth process involving the use of citrate-stabilised seed crystals and their subsequent growth in a series of reaction solutions containing [AuCl4]−, ascorbic acid and the cationic surfactant cetyltrimethylammonuim bromide (CTAB). Electron diffraction analysis and HRTEM images of mature nanorods showed superpositions of two specific pairs of crystallographic zones, either and or and , which were consistent with a cyclic penta-twinned crystal with five {111} twin boundaries arranged radially to the [110] direction of elongation. The nanorods have an idealised 3-D prismatic morphology with ten {111} end faces and five {100} or {110} side faces, or both. TEM studies of crystals at various stages of growth indicated that the seed crystals are initially transformed by growth and aggregation into decahedral penta-twinned
crystals, 4% of which become elongated when a fresh reaction solution is added, whilst the remaining twins grow isometrically. Reiteration of this procedure increases the length of the existing nanorods, induces further transformation of isometric particles to produce a second (and third) population of shorter, wider nanorods, and increases the size of the isometric crystals. The data indicate that symmetry breaking in fcc metallic structures to produce anisotropic nanoparticles is based on an intrinsic structural mechanism (twinning) that is subsequently modulated extrinsically during growth in solution by specific adsorption of AuI–surfactant complexes on the side faces/edges of the isometric penta-twinned crystals and which is responsible for the preferential growth along the common [110] axis. We propose that the coupling of multiple twinning and habit modification is a general mechanism that applies to other experimental
procedures (electrochemical, inverse micellar media) currently used to prepare metallic nanoparticles with a high aspect ratio.
921 citations
"Gold nanorod production by cyanobac..." refers background in this paper
...CTAB (cetyl trimethylammonium bromide) is required in most of the conventional chemical synthesis methods of nanorods (Johnson et al. 2002), but is toxic in photothermal therapy and drug delivery systems....
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TL;DR: The use of geranium leaves and its endophytic fungus in the extra-cellular synthesis of gold nanoparticles and the possibility of achieving nanoparticle shape control in a host leaf–fungus system is potentially exciting.
Abstract: Development of biologically inspired experimental processes for the synthesis of nanoparticles is an important branch of nanotechnology. In this paper, we report on the use of geranium leaves (Pelargonium graveolens) and its endophytic fungus in the extra-cellular synthesis of gold nanoparticles. Sterilized geranium leaves and an endophytic fungus (Colletotrichum sp.) growing in the leaves were separately exposed to aqueous chloroaurate ions. In both cases, rapid reduction of the metal ions was observed resulting in the formation of stable gold nanoparticles of variable size. In the case of gold nanoparticles synthesized using geranium leaves, the reducing and capping agents appear to be terpenoids while they are identified to be polypeptides/enzymes in the Colletotrichum sp. case. The biogenic gold nanoparticles synthesized using the fungus were essentially spherical in shape while the particles grown using the leaves exhibited a variety of shapes that included rods, flat sheets and triangles. While the exact reasons for shape variability are not clear at this stage, the possibility of achieving nanoparticle shape control in a host leaf–fungus system is potentially exciting.
858 citations
"Gold nanorod production by cyanobac..." refers background in this paper
...An earlier study with Geranium leaf extract reported the formation of a mixture of gold nanorods along with flat sheets and triangles (Shankar et al. 2003)....
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TL;DR: In this paper, the authors used live plants for the fabrication of nanoparticles and found that the Au nanoparticles are in a crystalline state and showed defects such as twins in the crystal structure and icosahedral nanoparticles were found.
Abstract: In modern nanotechnology one of the most exciting areas is the interaction between inorganic quantum dots and biological structures. For instance gold clusters surrounded by a shell of organic ligands covalently attach to proteins or other biological substances and can be used for labeling in structural biology. In the present report we show the possibility of using live plants for the fabrication of nanoparticles. Alfalfa plants were grown in an AuCl4 rich environment. The absorption of Au metal by the plants was confirmed by X-ray absorption studies (XAS), and transmission electron microscopy (TEM). Atomic resolution analysis confirmed the nucleation and growth of Au nanoparticles inside the plant and that the Au nanoparticles are in a crystalline state. Images also showed defects such as twins in the crystal structure, and in some cases icosahedral nanoparticles were found. X-ray EDS studies corroborated that the nanoparticles are pure gold. This is the first report on the formation of gold nanoparticl...
845 citations