Active Plasmonics with Responsive, Binary Assemblies of Gold Nanorods and Nanospheres.
Ontology highlight
ABSTRACT:
SUBMITTER: Szustakiewicz P
PROVIDER: S-EPMC8465109 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Vitrimers represent a new class of smart materials. They are covalently crosslinked like thermosets, yet they can be reprocessed like thermoplastics. The underlying mechanism is the rapid exchange reactions which form new bonds while breaking the old ones. So far, heating is the most widely used stimulus to activate the exchange reaction. Compared to heating, light not only is much more convenient to achieve remote and regional control, but can also offer fast healing. Gold nanospheres are excellent photothermal agents, but they are difficult to disperse into vitrimers as they easily aggregate. In this paper, we use polydopamine to prepare gold nanospheres. The resultant polydopamine-coated gold nanospheres (GNS) can be well dispersed into epoxy vitrimers, endowing epoxy vitrimers with light responsivity. The composites can be reshaped permanently and temporarily with light at different intensity. Efficient surface patterning and healing are also demonstrated.
| S-EPMC6414927 | biostudies-literature
Project description:Environmentally responsive nanoassemblies based on polypeptides and nanoparticles can have a number of promising biological/biomedical applications. We report the generation of gold nanorod (GNR)-elastin-like polypeptide (ELP) nanoassemblies whose optical response can be manipulated based on exposure to near-infrared (NIR) light. Cysteine-containing ELPs were self-assembled on GNRs mediated by gold-thiol bonds, leading to the generation of GNR-ELP nanoassemblies. Exposure of GNR-ELP assemblies to NIR light resulted in the heating of GNRs due to surface plasmon resonance. Heat transfer from the GNRs resulted in an increase in temperature of the self-assembled ELP above its transition temperature (Tt), which led to a phase transition and aggregation of the GNR-ELP assemblies. This phase transition was detected using an optical readout (increase in optical density); no change in optical behavior was observed in the case of either ELP alone or GNR alone. The optical response was reproducibele and reversible across a number of cycles following exposure to or removal of the laser excitation. Our results indicate that polypeptides may be interfaced with GNRs resulting in optically responsive nanoasssemblies for sensing and drug delivery applications.
| S-EPMC2888953 | biostudies-literature
Project description:Gold nanoparticles (GNPs) are widely used for biomedical applications due to unique optical properties, established synthesis methods, and biological compatibility. Despite important applications of plasmonic heating in thermal therapy, imaging, and diagnostics, the lack of quantification in heat generation leads to difficulties in comparing the heating capability for new plasmonic nanostructures and predicting the therapeutic and diagnostic outcome. This study quantifies GNP heat generation by experimental measurements and theoretical predictions for gold nanospheres (GNS) and nanorods (GNR). Interestingly, the results show a GNP-type dependent agreement between experiment and theory. The measured heat generation of GNS matches well with theory, while the measured heat generation of GNR is only 30% of that predicted theoretically at peak absorption. This then leads to a surprising finding that the polydispersity, the deviation of nanoparticle size and shape from nominal value, significantly influences GNR heat generation (>70% reduction), while having a limited effect for GNS (<10% change). This work demonstrates that polydispersity is an important metric in quantitatively predicting plasmonic heat generation and provides a validated framework to quantitatively compare the heating capabilities between gold and other plasmonic nanostructures.
| S-EPMC4956767 | biostudies-literature
Project description:Solution-phase self-assembly of anisotropic nanoparticles into complex 2D and 3D assemblies is one of the most promising strategies toward obtaining nanoparticle-based materials and devices with unique optical properties at the macroscale. However, controlling this process with single-particle precision is highly demanding, mostly due to insufficient understanding of the self-assembly process at the nanoscale. We report the use of in situ environmental scanning transmission electron microscopy (WetSTEM), combined with UV/vis spectroscopy, small-angle X-ray diffraction (SAXRD) and multiscale modeling, to draw a detailed picture of the dynamics of vertically aligned assemblies of gold nanorods. Detailed understanding of the self-assembly/disassembly mechanisms is obtained from real-time observations, which provide direct evidence of the colloidal stability of side-to-side nanorod clusters. Structural details and the forces governing the disassembly process are revealed with single particle resolution as well as in bulk samples, by combined experimental and theoretical modeling. In particular, this study provides unique information on the evolution of the orientational order of nanorods within side-to-side 2D assemblies and shows that both electrostatic (at the nanoscale) and thermal (in bulk) stimuli can be used to drive the process. These results not only give insight into the interactions between nanorods and the stability of their assemblies, thereby assisting the design of ordered, anisotropic nanomaterials but also broaden the available toolbox for in situ tracking of nanoparticle behavior at the single-particle level.
| S-EPMC7645924 | biostudies-literature
Project description:Digital coding and digital modulation are the foundation of modern information science. The combination of digital technology with metamaterials provides a powerful scheme for spatial and temporal controls of electromagnetic waves. Such a technique, however, has thus far been limited to the control of free-space light. Its application to plasmonics to shape subwavelength fields still remains elusive. Here, we report the design and experimental realization of a tunable conformal plasmonic metasurface, which is capable of digitally coding and modulating designer surface plasmons at the deep-subwavelength scale. Based on dynamical switching between two discrete dispersion states in a controlled manner, we achieve digital modulations of both amplitude and phase of surface waves with nearly 100% modulation depth on a single device. Our study not only introduces a new approach for active dispersion engineering, but also constitutes an important step towards the realization of subwavelength integrated plasmonic circuits.
| S-EPMC8288847 | 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:The ability of localized surface plasmons to squeeze light and engineer nanoscale electromagnetic fields through electron-photon coupling at dimensions below the wavelength has turned plasmonics into a driving tool in a variety of technological applications, targeting novel and more efficient optoelectronic processes. In this context, the development of active control of plasmon excitations is a major fundamental and practical challenge. We propose a mechanism for fast and active control of the optical response of metallic nanostructures based on exploiting quantum effects in subnanometric plasmonic gaps. By applying an external dc bias across a narrow gap, a substantial change in the tunneling conductance across the junction can be induced at optical frequencies, which modifies the plasmonic resonances of the system in a reversible manner. We demonstrate the feasibility of the concept using time-dependent density functional theory calculations. Thus, along with two-dimensional structures, metal nanoparticle plasmonics can benefit from the reversibility, fast response time, and versatility of an active control strategy based on applied bias. The proposed electrical manipulation of light using quantum plasmonics establishes a new platform for many practical applications in optoelectronics.
| S-EPMC4730853 | biostudies-other
Project description:Cancer chemotherapy can be hindered by drug resistance which leads to lower drug efficiency. Here, we have developed a drug delivery system that tethers doxorubicin to the surface of gold nanorods via a pH-sensitive linkage (AuNRs@DOX), for a combined photothermal and chemical therapy for cancer. First, AuNRs@DOX is ingested by HepG2 liver cancer cells. After endocytosis, the acidic pH triggers the release of doxorubicin, which leads to chemotherapeutic effects. The gold nanorods are not only carriers of DOX, but also photothermal conversion agents. In the presence of an 808 nm near-infrared laser, AuNRs@DOX significantly enhance the cytotoxicity of doxorubicin via the photothermal effect, which induces elevated apoptosis of hepG2 cancer cells, leading to better therapeutic effects in vitro and in vivo.
| S-EPMC6035373 | biostudies-literature
Project description:Stable aqueous dispersions of citrate-stabilized gold nanorods (cit-GNRs) have been prepared in scalable fashion by surfactant exchange from cetyltrimethylammonium bromide (CTAB)-stabilized GNRs, using polystyrenesulfonate (PSS) as a detergent. The surfactant exchange process was monitored by infrared spectroscopy, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS). The latter established the quantitative displacement of CTAB (by PSS) and of PSS (by citrate). The Cit-GNRs are indefinitely stable at low ionic strength, and are conducive to further ligand exchange without loss of dispersion stability. The reliability of the surface exchange process supports the systematic analysis of ligand structure on the hydrodynamic size of GNRs, as described in a companion paper.
| S-EPMC4334258 | biostudies-literature
Project description:We propose a two-step ligand exchange for the selective end-functionalization of gold nanorods (AuNR) by thiolated cyclodextrin (CD) host molecules. As a result of the complete removal of the precursor capping agent cetyltrimethylammonium bromide (CTAB) by a tetraethylene glycol derivative, competitive binding to the host cavity was prevented, and reversible, light-responsive assembly and disassembly of the AuNR could be induced by host-guest interaction of CD on the nanorods and a photoswitchable arylazopyrazole cross-linker in aqueous solution. The end-to-end assembly of AuNR could be effectively controlled by irradiation with UV and visible light, respectively, over four cycles. By the introduction of AAP, previous disassembly limitations based on the photostationary states of azobenzenes could be solved. The combination photoresponsive interaction and selectively end-functionalized nanoparticles shows significant potential in the reversible self-assembly of inorganic-organic hybrid nanomaterials.
| S-EPMC6604721 | biostudies-literature