Kinetic Regulation of the Synthesis of Pentatwinned Gold Nanorods below Room Temperature
Ontology highlight
ABSTRACT:
SUBMITTER: Sanchez-Iglesias A
PROVIDER: S-EPMC8573768 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Metallic alloy nanoparticles (NPs) exhibit interesting optical, electrical and catalytic properties, dependent on their size, shape and composition. In particular, silver-gold alloy NPs are widely applied as model systems to better understand the syntheses and formation (kinetics) of alloy NPs, as the two elements are fully miscible. Our study targets product design via environmentally friendly synthesis conditions. We use dextran as the reducing and stabilizing agent for the synthesis of homogeneous silver-gold alloy NPs at room temperature. Our approach is a one-pot, low temperature, reaction-controlled, green and scalable synthesis route of well-controlled composition and narrow particle size distribution. The composition over a broad range of molar gold contents is confirmed by scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy (STEM-EDX) measurements and auxiliary inductively coupled plasma-optical emission spectroscopy measurements (ICP-OES). The distributions of the resulting particles in size and composition are obtained from multi-wavelength analytical ultracentrifugation using the optical back coupling method and further confirmed by high-pressure liquid chromatography. Finally, we provide insight into the reaction kinetics during the synthesis, discuss the reaction mechanism and demonstrate possibilities for scale-up by a factor of more than 250 by increasing the reactor volume and NP concentration.
| S-EPMC9972530 | biostudies-literature
Project description:Nobel metal nanoparticles with tunable morphologies are highly desirable due to their unique electronic, magnetic, optical, and/or catalytic features. Here we report the use of multilayered graphdyine (GD) as a substrate for the reductant-free, room-temperature synthesis of single-crystal Au nanostructures with tunable morphology. We find that the GD template rich in sp-carbon atoms possesses high affinity with Au atoms on the {111} facets, and that the intrinsic reductivity of GD facilitates the rapid growth of Au nanoplates. The introduction of single-stranded DNA strands further results in the synthesis of Au nanostructures with decreased anisotropy, i.e., polygons and flower-like nanoparticles. The DNA-guided tunable Au growth arises from the strong adsorption of DNA on the GD template that alters the uniformity of the interface, which provides a direct route to synthesize Au nanostructures with tailorable morphology and photonic properties.
| S-EPMC7256954 | biostudies-literature
Project description:Asymmetric carbon-hydrogen (C-H) activation reactions often rely on desymmetrization of prochiral C-H bonds on the same achiral molecule, using a chiral catalyst. Here, we report a kinetic resolution via palladium-catalyzed enantioselective C-H iodination in which one of the enantiomers of a racemic benzylic amine substrates undergoes faster aryl C-H insertion with the chiral catalysts than the other. The resulting enantioenriched C-H functionalization products would not be accessible through desymmetrization of prochiral C-H bonds. The exceedingly high relative rate ratio (k(fast)/k(slow) up to 244), coupled with the subsequent iodination of the remaining enantiomerically enriched starting material using a chiral ligand with the opposite configuration, enables conversion of both substrate enantiomers into enantiomerically pure iodinated products.
| S-EPMC4382011 | biostudies-literature
Project description:Asymmetric gold-catalyzed hydrocarboxylations are reported that show broad substrate scope. The hydrophobic effect associated with in situ-formed aqueous nanomicelles gives good to excellent ee's of product lactones. In-flask product isolation, along with the recycling of the catalyst and the reaction medium, are combined to arrive at an especially environmentally friendly process.
| S-EPMC4193796 | biostudies-literature
Project description:The immune system may respond to engineered nanomaterials (ENM) through inflammatory reactions. The NLRP3 inflammasome responds to a wide range of ENM, and its activation is associated with various inflammatory diseases. The objective of the study was to compare the effects of gold ENM of different shapes on NLRP3 inflammasome activation and related signalling pathways. Differentiated THP-1 cells (wildtype, ASC- or NLRP3-deficient), were exposed to PEGylated gold nanorods, nanostars, and nanospheres. Exposed cells were subjected to gene expression analysis. Nanorods, but not nanostars or nanospheres, showed NLRP3 inflammasome activation. ASC- or NLRP3-deficient cells did not show this effect. Gold nanorod-induced NLRP3 inflammasome activation was accompanied by downregulated sterol/cholesterol biosynthesis, oxidative phosphorylation, and purinergic receptor signalling. In conclusion, the shape and surface chemistry of gold nanoparticles determine NLRP3 inflammasome activation.
2023-05-29 | GSE233641 | GEO
Project description:Protein X-ray structures are determined with ionizing radiation that damages the protein at high X-ray doses. As a result, diffraction patterns deteriorate with the increased absorbed dose. Several strategies such as sample freezing or scavenging of X-ray-generated free radicals are currently employed to minimize this damage. However, little is known about how the absorbed X-ray dose affects time-resolved Laue data collected at physiological temperatures where the protein is fully functional in the crystal, and how the kinetic analysis of such data depends on the absorbed dose. Here, direct evidence for the impact of radiation damage on the function of a protein is presented using time-resolved macromolecular crystallography. The effect of radiation damage on the kinetic analysis of time-resolved X-ray data is also explored.
| S-EPMC3284346 | biostudies-literature
Project description:Achieving organic room-temperature phosphorescence (RTP) in a solvent-free liquid state is a challenging task because the liquid state provides a less rigid environment than the crystal. Here, we report that an unsymmetrical heteroaromatic 1,2-diketone forms an organic RTP liquid. This diketone exists as a kinetically stable supercooled liquid, which resists crystallisation even under pricking or shearing stresses, and remains as a liquid for several months. The unsymmetrical diketone core is flexible, with eight distinct conformers possible, which prevents nucleation and growth for the liquid-solid transition. Interestingly, the thermodynamically stable crystalline solid-state was non-emissive. Thus, the RTP of the diketone was found to be liquiefaction-induced. Single-crystal X-ray structure analysis revealed that the diminished RTP of the crystal is due to insufficient intermolecular interactions and restricted access to an emissive conformer. Our work demonstrates that flexible unsymmetrical skeletons are promising motifs for bistable liquid-solid molecular systems, which are useful for the further development of stimuli-responsive materials that use phase transitions.
| S-EPMC8580009 | biostudies-literature
Project description:Gold nanorods (GNRs) exhibit a tunable longitudinal surface plasmon resonance (LSPR) that depends on the GNR aspect ratio (AR). Independently controlling the AR and size of GNRs remains challenging but is important because the scattering intensity strongly depends on the GNR size. Here, we report a secondary (seeded) growth procedure, wherein continuous addition of ascorbic acid (AA) to a stirring solution of GNRs, stabilized by cetyltrimethylammonium bromide (CTAB) and synthesized by a common GNR growth procedure, deposits the remaining (~70%) of the Au precursor onto the GNRs. The growth phase of GNR synthesis is often performed without stirring, since stirring has been believed to reduce the yield of rod-shaped nanoparticles, but we report that stirring coupled with continuous addition of AA during secondary growth allows improved control over the AR and size of GNRs. After a common primary GNR growth procedure, the LSPR of GNRs is ~820 nm, which can be tuned between ~700-880 nm during secondary growth by adjusting the rate of AA addition or adding benzyldimethylhexadecylammonium chloride hydrate (BDAC). This approach for secondary growth can also be used with primary GNRs of different ARs to achieve different LSPRs and can likely be extended to nanoparticles of different shapes and other metals.
| S-EPMC3883054 | biostudies-literature
Project description:The synthesis of two new phosphane-gold(I)-napthalimide complexes has been performed and characterized. The compounds present luminescent properties with denoted room temperature phosphorescence (RTP) induced by the proximity of the gold(I) heavy atom that favors intersystem crossing and triplet state population. The emissive properties of the compounds together with the planarity of their chromophore were used to investigate their potential as hosts in the molecular recognition of different polycyclic aromatic hydrocarbons (PAHs). Naphthalene, anthracene, phenanthrene, and pyrene were chosen to evaluate how the size and electronic properties can affect the host:guest interactions. Stronger affinity has been detected through emission titrations for the PAHs with extended aromaticity (anthracene and pyrene) and the results have been supported by DFT calculation studies.
| S-EPMC8122727 | biostudies-literature
Project description:Metal patterning via additive manufacturing has been phasing-in to broad applications in many medical, electronics, aerospace, and automotive industries. While previous efforts have produced various promising metal-patterning strategies, their complexity and high cost have limited their practical application in rapid production and prototyping. Herein, a one-step gold printing technique based on anion-assisted photochemical deposition (APD), which can directly print highly conductive gold patterns (1.08 × 107 S m-1 ) under ambient conditions without post-annealing treatment, is introduced. Uniquely, the APD uses specific ion effects with projection lithography to pattern Au nanoparticles and simultaneously sinter them into tunable porous gold structures. The significant influence of kosmotropic or chaotropic anions in the precursor ink on tuning the morphologies and conductivities of the printed patterns by employing a series of different ions, including Cl- ions, in the printing process is presented. Additionally, the resistance stabilities and the electrochemical properties of the APD-printed gold patterns are carefully investigated. The high conductivity and excellent conformability of the printed Au electrodes are demonstrated with reliable performance in electrophysiological signal delivery and acquisition for biomedical applications. This work exploits the potential of photochemical-deposition-based metal patterning in flexible electronic manufacturing.
| S-EPMC9884391 | biostudies-literature