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Gold nanomaterials (GNMs) have unique optical properties with less antigenicity, and their physicochemical properties have strong relation with an immunological response at bio-interface including antigenicity. An interpretation of this correlation would significantly impact on the clinical and theranostic applications of GNMs. Herein, we studied the effect of GNMs morphology on the cytotoxicity (in-vitro), innate immune responses, hepatotoxicity, and nephrotoxicity (in-vivo studies) using gold nano-cups (GNCs), porous gold nanospheres (PGNSs) and solid gold nano particles (SGNPs) coated with the same ligand to ensure similar surface chemistry. The cytotoxicity was assessed via sulfo-rhodamine B (SRB) assay, and the cytotoxicity data showed that morphological features at nanoscale dimensions like surface roughness and hollowness etc. have a significant impact on cellular viability. The biochemical and histopathological study of liver and kidney tissues also showed that all GNMs did not show any toxicity even at high concentration (100 μL). The relative quantification of cytokine gene expression of TNF-α, IFN-γ, IL-4, 1L-6, and 1L-17 (against each morphology) was checked after in-vivo activation in mice. Among the different nanogold morphologies, PVP stabilized GNCs (PVP-GNCs) showed the highest release of pro-inflammatory cytokines, which might be due to their high surface energy and large surface area for exposure as compared to other nanogold morphologies studied. The pro-inflammatory cytokine release could be suppressed by coating with some anti-inflammatory polymer, i.e., inulin. The in-vitro results of pro-inflammatory (TNF-α, IL-1) cytokines also suggested that all GNMs may induce activation of macrophages and Th1 immune response. The in-vivo activation results showed a decrease in mRNA expression of the cytokines (TNF-α, IFN-γ, IL-4, 1L-6 and 1L-17). Based on these findings, we proposed that the shape and morphology of GNMs control their immune response at nano-bio interface, and it must be considered while designing their role for different biomedical applications like immuno-stimulation and bio-imaging., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

We report the synthesis and evaluation of lecithin-gold hybrid nanocarriers for the oral delivery of drugs with improved pharmacokinetics, Au-drug interactive bioactivity and controlled drug releasing behavior at physiological pH inside human body. For this purpose, diacerein, a hydrophobic anti-arthritic drug, was loaded in lecithin NPs (LD NPs), which were further coated by Au NPs either by in-situ production of Au NPs on LD NPs or by employing pre-synthesized Au NPs. All LDAu NPs were found to release drug selectively at the physiological pH of 7.4 and showed 2.5 times increase in the oral bioavailability of diacerein. Pharmacological efficacy was significantly improved i.e., greater than the additive effect of diacerein and Au NPs alone. LDAu NPs started suppressing inflammation at first phase, whereas LD NPs showed activity in the second phase of inflammation. These results indicate the interaction of Au NPs with prostaglandins and histaminic mediators of first phase of carrageenan induced inflammation. Acute toxicity study showed no hepatic damage but the renal toxicity parameters were close to the upper safety limits. Toxicity parameters were dependent on surface engineering of LDAu NPs. Apart from enhancing the oral bioavailability of hydrophobic drugs and improving their anti-inflammatory activity, these hybrid nanocarriers may have potential applications in gold-based photothermal therapy and the tracing of inflammation at atherosclerotic and arthritic site., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We report a versatile approach for the synthesis of porous gold nanocups, porous gold nanospheres and solid gold nanoparticles. Gold nanocups are formed by the slow reduction of gold salt (HAuCl4⋅3H2O) using aminoantipyrene (AAP) as a reducing agent. Adding polyvinylpyrrolidone (PVP) to the gold salt followed by reduction with AAP resulted in the formation of porous gold nanospheres. Microwave irradiation of both of these porous gold particles resulted in the formation of slightly smaller but solid gold particles. All these nanoparticles are thoroughly characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and bright-field tomography. Due to the larger size, porous nature, low density and higher surface area, these nanomaterials may have interesting applications in catalysis, drug delivery, phototherapy and sensing., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Water-soluble fluorescent copper, silver and gold nanoclusters with quantum yields of 2.2, 6.8 and 5.3%, respectively, are prepared by a robust photoreduction of their inorganic precursors in the presence of poly (methacrylic acid) functionalized with pentaerythritol tetrakis 3-mercaptopropionate., (This journal is © The Royal Society of Chemistry 2012)

At present, thiol ligands are generally used whenever the classical Brust-Schiffrin two-phase method is employed to prepare metal nanoparticles. In general, the previous research was mainly focused on utilizing small molecular thiol compounds or thiol polymers as the stabilizers in organic phase to obtain small sized and uniform gold nanoparticles (Au NPs). Such preparations are usually associated with the problems of ligand exchange on the nanoparticle's surface due to strong Au-thiol interaction. Herein, we report an approach to produce fairly uniform Au NPs with diameters about 2-6 nm using thioether end-functional polymer ligands (DDT-PVAc and PTMP-PVAc) as the capping agents. These nanoparticles are thoroughly characterized using DLS, TEM, UV-Vis spectroscopy and other complementary techniques. The results indicate that multidentate thioether polymeric ligands (PTMP-PVAc) lead to formation of smaller but special 'multimer' morphology in organic phase; whereas fairly uniform nanoparticles are produced using monodentate thioether functionalized ligands (DDT-PVAc). Further modification of such polymer ligands to introduce the hydrophilic functionalities realizes the phase transfer of Au NPs from organic to aqueous media.

Latent fingerprints are made visible in a single step by in situ growth of gold nanoparticles on ridge patterns. The chemicals, among the essential components of human sweat, found responsible for the formation and assembly of gold nanoparticles are screened and used as ink to write invisible patterns, using common ball pen and inkjet printer, which are then developed by selectively growing gold nanoparticles by soaking them in gold salt solution.

Aggregation of gold nanoparticles into soluble spherical assemblies using bi-functional ligands i.e., dithiols has recently been demonstrated but with limited control over the size of such assemblies. Herein, we report a new approach to further control the size of water dispersible spherical assemblies by confining gold nanoparticles in tiny oil droplets in water (oil-in-water emulsions) followed by their cross-linking with alkanedithiols. By controlling the size of the oil droplets and the concentration of nanoparticles, the size of spherical aggregates can be controlled from 20 to 400 nm. Cryo-TEM micrographs confirm the formation of covalently-linked soluble spherical nanoparticle assemblies within the oil emulsions in water. Such size-controlled nanoparticle assemblies may have several potential applications including those in gas sensors, controlled delivery, and optical coatings., (Copyright 2010 Elsevier Inc. All rights reserved.)

Natural unmodified rhamnolipids are thermally self-assembled into soft microtubules, which can produce gold nanoparticles onto themselves due to the presence of rhamnose sugar moieties at their surface. The loading of gold nanoparticles on composite microtubules can be controlled by varying the concentration of gold salt to rhamnolipid and the reaction temperature. The composite rhamnolipid-gold nanoparticle microtubules are then heat treated to produce porous gold microwire-like structures with fairly controlled nanostructured features, which may have interesting applications in catalysis, biosensing and electronics., (Copyright 2010 Elsevier Inc. All rights reserved.)

A new methodology is described for the one-step aqueous preparation of highly monodisperse gold nanoparticles with diameters below 5 nm using thioether- and thiol-functionalized polymer ligands. The particle size and size distribution was controlled by subtle variation of the polymer structure. It was shown that poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) were the most effective stabilizing polymers in the group studied and that relatively low molar mass ligands (approximately 2500 g/mol) gave rise to the narrowest particle size distributions. Particle uniformity and colloidal stability to changes in ionic strength and pH were strongly affected by the hydrophobicity of the ligand end group. "Multidentate" thiol-terminated ligands were produced by employing dithiols and tetrathiols as chain-transfer agents, and these ligands gave rise to particles with unprecedented control over particle size and enhanced colloidal stability. It was found throughout that dynamic light scattering (DLS) is a very useful corroboratory technique for characterization of these gold nanoparticles in addition to optical spectroscopy and TEM.

Based on protein folding considerations, a pentapeptide ligand, CALNN, which converts citrate-stabilized gold nanoparticles into extremely stable, water-soluble gold nanoparticles with some chemical properties analogous to those of proteins, has been designed. These peptide-capped gold nanoparticles can be freeze-dried and stored as powders that can be subsequently redissolved to yield stable aqueous dispersions. Filtration, size-exclusion chromatography, ion-exchange chromatography, electrophoresis, and centrifugation can be applied to these particles. The effect of 58 different peptide sequences on the electrolyte-induced aggregation of the nanoparticles was studied. The stabilities conferred by these peptide ligands depended on their length, hydrophobicity, and charge and in some cases resulted in further improved stability compared with CALNN, yielding detailed design criteria for peptide capping ligands. A simple strategy for the introduction of recognition groups is proposed and demonstrated with biotin and Strep-tag II.

Gold nanoparticles (Au NPs) of different sizes were supported on fibrous silica nanospheres (KCC-1) by various methods. The size and the location of the Au NPs on the support were found to depend on the preparation method. The KCC-1-supported Au NPs were thoroughly characterized by using HR-TEM, XRD, X-ray photoelectron spectroscopy, UV, and Brunauer-Emmett-Teller surface area measurements and were applied in catalysis for the oxidation of CO. The catalytic performance is discussed in relation to the morphological properties of KCC-1. [ABSTRACT FROM AUTHOR]

A series of monolayer protected gold nanoparticle colloidal solutions have been prepared with average sizes in the 2-15nm range. If a drop of such a colloidal suspension is deposited onto a Si3N4 substrate and the solvent allowed to evaporate, the particles have a tendency to self-assemble into monolayer rafts with varying degrees of structural order depending on the initial mono-dispersity of the particles. The thermal stability of these selfassembled gold nanoparticle rafts as a function of particle size, heating method, heating rate and ligand identity have been assessed in this study. In-situ TEM studies show that sub-8nm Au nanoparticles on Si3N4 have a tendency to coarsen upon slow heating, whereas those comprised of larger particles exhibit densification. Increasing the heating rate for the smaller particles promoted densification, forcing them to form highly interconnected string-like structures. Finally, rafts of sub-4nm alkanethiol protected Au nanoparticles are shown to sinter spontaneously under ambient conditions at room temperature on the timescale of several months. This unexpected effect may have important implications for the long term structural stability of any device constructed from sub-4nm gold nanoparticles. [ABSTRACT FROM AUTHOR]

The article reports on a single-step synthesis of near- monodisperse gold nanoparticles in the 1-4 nm size range. It presents that the particle size is controlled by the ratio of Au to capping ligand, and the particles are readily obtainable in both aqueous and non aqueous solutions. To prepare the particles, an aqueous solution of hydrogen tetrachloroaurate (20 ml, 0.5 mM) was reduced by the addition of a freshly prepared solution of sodium borohydride (2 ml, 50 mM) in the presence of a water-soluble alkyl thioether end-functionalized poly(methacrylic acid) stabilizer.