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This paper presents a review in gold nanoparticles focusing on chemical reduction synthesis mechanisms. We hope to aid students and researchers starting in the nanotechnology field by compiling the most used synthesis methods, so ...
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This paper presents a review in gold nanoparticles focusing on chemical reduction synthesis mechanisms. We hope to aid students and researchers starting in the nanotechnology field by compiling the most used synthesis methods, so they can select the ones that best suit them. The compiled information in this paper approached the following methods: Turkevich Method; Synthesis with NaBH4 with/without citrate; Seeding- Growth; Synthesis by Ascorbic Acid; Green Synthesis; Brust-Schiffrin; and synthesis using other reducing agents. Papers that had clear synthesis information were selected for this work, but that doesn't mean they were synthesis focused. Over 150 papers were analyzed. After compiling the information for these papers, we can conclude that nanoscience is revolutionizing all the areas that are applied to. (C) 2019 Elsevier B.V. All rights reserved.
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Branched gold nanoparticles with sharp tips are considered excellent candidates for sensing and field enhancement applications. Here, a rapid and simple synthesis strategy is presented that generates highly branched gold nanoparti...
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Branched gold nanoparticles with sharp tips are considered excellent candidates for sensing and field enhancement applications. Here, a rapid and simple synthesis strategy is presented that generates highly branched gold nanoparticles with hollow cores and a ca.100% yield through a simple one-pot seedless reaction at room temperature in the presence of Triton X-100. It is shown that multibranched hollow gold nanoparticles of tunable dimensions, branch density and branch length can be obtained by adjusting the concentrations of the reactants. Insights into the formation mechanism point toward an aggregative type of growth involving hollow core formation first, and branching thereafter. The pronounced near-infrared (NIR) plasmon band of the nanoparticles is due to the combined contribution from hollowness and branching, and can be tuned over a wide range (approximate to 700-2000 nm). It is also demonstrated that the high environmental sensitivity of colloidal dispersions based on multibranched hollow gold nanoparticles can be boosted even further by separating the nanoparticles into fractions of given sizes and improved monodispersity by means of a glycerol density gradient. The possibility to obtain highly monodisperse multibranched hollow gold nanoparticles with predictable dimensions (50-300 nm) and branching and, therefore, tailored NIR plasmonic properties, highlights their potential for theranostic applications.
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This article reports that ganciclovir-loaded gold nanoparticles were developed via glutathione surface modification. Citrate-reduced gold nanoparticles were prepared first from chloroauric acid. Further the surface of gold nanopar...
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This article reports that ganciclovir-loaded gold nanoparticles were developed via glutathione surface modification. Citrate-reduced gold nanoparticles were prepared first from chloroauric acid. Further the surface of gold nanoparticles was modified with glutathione. Then ganciclovir was loaded onto the glutathione-modified gold nanoparticles through the reaction between carboxyl group of glutathione and amino group of ganciclovir. Gold nanoparticles were characterized by photon correlation spectroscopy, transmission electron microscopy and infrared spectroscopy. Drug loading of 87.27+/-2.52% was observed for ganciclovir-loaded gold nanoparticles. The particle size distribution of gold nanoparticles ranged from 26.3 to 31 nm. Thus ganciclovir-loaded gold nanoparticles were successfully prepared, which might further improve the oral bioavailability of ganciclovir.
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Cationic polyethyleneimine (PEI)-conjugated gold nanoparticles (AuNPs) that are chemically and physically stable under physiological conditions are an ideal candidate for certain bio-medical applications, in particular DNA transfe...
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Cationic polyethyleneimine (PEI)-conjugated gold nanoparticles (AuNPs) that are chemically and physically stable under physiological conditions are an ideal candidate for certain bio-medical applications, in particular DNA transfection. However, the issue remains in reproducibly generating uniform stable species, which can cause the inadequate characterization of the resulting product under relevant conditions and timepoints. The principal objective of the present study was to develop an optimized and reproducible synthetic route for preparing stable PEI-conjugated AuNPs (Au-PEIs). To achieve this objective, a parallel multi-parametric approach involving a total of 96 reaction studies evaluated the importance of 6 key factors: PEI molar mass, PEI structure, molar ratio of PEI/Au, concentration of reaction mixtures, reaction temperature, and reaction time. Application of optimized conditions exhibited narrow size distributions with characteristic surface plasmon resonance absorption and positive surface charge. The optimized Au-PEI product generated by this study exhibits exceptional stability under a physiological isotonic medium (phosphate-buffered saline) over 48 h and shelf-life in ambient condition without any significant change or sedimentation for at least 6 months. Furthermore, the optimized Au-PEI product was highly reproducible. Contributions from individual factors were elucidated using a broad and orthogonal characterization suite examining size and size distribution, optical absorbance, morphological transformation (agglomeration/aggregation), surface functionalities, and stability. Overall, this comprehensive multi-parametric investigation, supported by thorough characterization and rigorous testing, provides a robust foundation for the nanomedicine research community to better synthesize nanomaterials for biomedical use.
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Mercury ions (Hg 2+ ) are widely found in the environment; it is considered a major pollutant.Therefore, the rapid and reliable detection of Hg 2+ is of great technical interest. In this study, a highly fluorescent, sensitive, and...
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Mercury ions (Hg 2+ ) are widely found in the environment; it is considered a major pollutant.Therefore, the rapid and reliable detection of Hg 2+ is of great technical interest. In this study, a highly fluorescent, sensitive, and selective fluorometric assay for detecting Hg 2+ ions was developed using vancomycin functionalized and polyethyleneimine stabilized gold nanoparticles (PEI-f-AuNPs@Van). The as-made gold nanoparticles were highly fluorescent, with excitation and emission maxima occurring at 320 nm and 418 nm, respectively. The size of nanoparticles was ?7 nm; a zeta potential of ?38.8 mV was determined. The XRD analysis confirmed that the nanoparticles possessed crystalline structure with face centerd cubic symmetry. Using the PEI-f-AuNP@Van probe, the detection limit of Hg 2+ ion was achieved up to 0.988 nM (within a linear range) by calculating the KSV. However, the detection limit in a natural environmental sample was shown to be 12.5 nM. Furthermore, the selectivity tests confirmed that the designed probe was highly selective to mercury (II) cations among tested other divalent cations. Owing to its sensitivity and selectivity, this approach for Hg 2+ ions detection can be utilized for the analysis of real water samples.
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We have found that the gold nanoparticles deposited on the ITO substrates show substantial acoustically induced circularly polarized light gyration (AILG). The effect exists only during simultaneous treatment by two coherent acous...
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We have found that the gold nanoparticles deposited on the ITO substrates show substantial acoustically induced circularly polarized light gyration (AILG). The effect exists only during simultaneous treatment by two coherent acoustical waves with frequencies 1 and 2 MHz. The maximally achieved value of the AILG susceptibility described by fourth-order axial tensor caused by probe circularly polarized acoustical field at power density about 3 W/cm(2) was equal to about 7.8 degrees/mm for circular acoustical wave polarization and was achieved at T = 4.2 K for samples possessing lower resistivity. We have discovered that maximal AILG coefficient is achieved for the samples possessing minimal resistivity. The investigated composites possess acoustically induced helicoidal grating which disappeared after 20 s after switching off the acoustical fields. (c) 2005 Elsevier B.V. All rights reserved.
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Gold nanoparticles are materials with unique optical properties that have made them very attractive for numerous biomedical applications. With the increasing discovery of techniques to synthesize novel nanoparticles such as star-s...
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Gold nanoparticles are materials with unique optical properties that have made them very attractive for numerous biomedical applications. With the increasing discovery of techniques to synthesize novel nanoparticles such as star-shaped gold nanoparticles for biomedical applications, the safety and performance of these new nanomaterials must be systematically assessed before use. In this study, gold nanostars (AuNSTs) with multibranched surface structures were synthesized, and their influence on the cytotoxicity of human skin fibroblasts and rat fat pad endothelial cells (RFPECs) were assessed and compared with that of gold nanospheres (AuNSPs) with unbranched surfaces. Results showed that the AuNSPs with diameters of approximately 61.46 nm showed greater toxicity with fibroblast cells and RFPECs compared with the synthesized AuNSTs with diameters of approximately 33.69 nm. The AuNSPs were lethal at concentrations of 40 g/mL for both cell lines, whereas the AuNSTs were less toxic at higher concentrations (400 g/mL). The calculated IC50 (50% inhibitory concentration) values of the AuNSPs exposed to fibroblast cells were greater at 1 and 4 days of culture (26.4 and 27.7 g/mL, respectively) compared with the RFPECs (13.6 and 13.8 g/mL, respectively), indicating that the AuNSPs have a greater toxicity to endothelial cells. It was proposed that possible factors that could be promoting the reduced toxicity effects of the AuNSTs to fibroblast cells and RFPECs, compared with the AuNSPs may be size, surface chemistry, and shape of the gold nanoparticles. The reduced cell toxicity observed with the AuNSTs suggests that AuNSTs may be a promising material for use in biomedical applications. (c) 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3449-3462, 2015.
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Gold nanoparticles prepared by trisodium citrate reduction of HAuCl4 in poly(vinylpyrrolidone) (PVP) ethanol solution were dispersed into PVP nanofibers by electrospinning. The optical property of Au nanoparticles before and after...
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Gold nanoparticles prepared by trisodium citrate reduction of HAuCl4 in poly(vinylpyrrolidone) (PVP) ethanol solution were dispersed into PVP nanofibers by electrospinning. The optical property of Au nanoparticles before and after electrospinning was measured by UV-Vis. The morphology and distribution of gold nanoparticles in PVP nanofibers were observed by transmission electron microscopy (TEM). The influence of the amount of Au added to and the concentration of PVP in electrospinning solution over the morphology of Au/PVP nanofibers were studied. (c) 2007 Wiley Periodicals, Inc.
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The use of optically controlled vapor bubbles for controlled synthesis and deposition at interfaces is a promising emerging technique, which is intrinsically limited by the ability of the system to provide enough heat for bubble f...
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The use of optically controlled vapor bubbles for controlled synthesis and deposition at interfaces is a promising emerging technique, which is intrinsically limited by the ability of the system to provide enough heat for bubble formation that is typically addressed using a plasmonic substrate. Herein, a simple and fast method for laser-controlled printing of plasmonic nanoparticles onto nonplasmonic substrates is shown. The laser fluence needed to print the nanoparticle was lowest for nanoparticles in resonance with the laser wavelength, but the technique is also effective off-resonance. Hierarchical assemblies were obtained, where melting was observed up to a micron from the focal point of the laser beam. The assemblies show plasmonic properties in the unmelted region, as shown by surface-enhanced Raman scattering spectroscopy measurements. This work will lead to future studies on controlling the hierarchical structure of nanoparticle assemblies formed at the bubble interface toward applications in sensing and devices.
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Composite nanoparticles of Au, Pd and Pt, and nanoparticles of transition metal oxides, MnO_2, were prepared by the sonochemical reduction of corresponding ions (Au(III), Pd(II), Pt(II), Pt(IV) and Mn(VII)) in an aqueous system in...
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Composite nanoparticles of Au, Pd and Pt, and nanoparticles of transition metal oxides, MnO_2, were prepared by the sonochemical reduction of corresponding ions (Au(III), Pd(II), Pt(II), Pt(IV) and Mn(VII)) in an aqueous system in the presence of surfactants. The prepared noble metal particles were stable and the sizes were of the order of nanometer with narrow distribution. Surfactants were found to he stabilizers for the noble metal nanoparticles as well as important sources of reducing species for the metal ions. In binary metallic particles, which were prepared from aqueous mixed solutions of noble metal ions, three possible constitutional forms were obtained. MnO_2 particles were reduce to water soluble Mn(II) ions by further sonication.
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