Unrestricted Chiral Patterning by Laser Writing in Liquid Crystalline and Plasmonic Nanocomposite Thin Films.

Obtaining hierarchical structures with arbitrarily controlled chirality remains a challenge. Here, thin films featuring chiroptically bipolar patterns are produced by a device utilizing microscale photothermal re-melting of materials exhibiting chirality synchronization. This device operates autonomously, guided by an algorithm that facilitates the homochiral growth of supramolecular organic helices through controlling their re-melting.

Active Plasmonics with Responsive, Binary Assemblies of Gold Nanorods and Nanospheres.

Self-assembly of metal nanoparticles has applications in the fabrication of optically active materials. Here, we introduce a facile strategy for the fabrication of films of binary nanoparticle assemblies. Dynamic control over the configuration of gold nanorods and nanospheres is achieved via the melting of bound and unbound fractions of liquid-crystal-like nanoparticle ligands.

In Situ Tracking of Colloidally Stable and Ordered Assemblies of Gold Nanorods.

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.

Supramolecular Chirality Synchronization in Thin Films of Plasmonic Nanocomposites.

Mirror symmetry breaking in materials is a fascinating phenomenon that has practical implications for various optoelectronic technologies. Chiral plasmonic materials are particularly appealing due to their strong and specific interactions with light. In this work we broaden the portfolio of available strategies toward the preparation of chiral plasmonic assemblies, by applying the principles of chirality synchronization-a phenomenon known for small molecules, which results in the formation of chiral domains from transiently chiral molecules.

Robust Synthesis of Gold Nanotriangles and their Self-Assembly into Vertical Arrays.

We report an efficient, seed-mediated method for the synthesis of gold nanotriangles (NTs) which can be used for controlled self-assembly. The main advantage of the proposed synthetic protocol is that it relies on using stable (over the course of several days) intermediate seeds. This stability translates into increasing time efficiency of the synthesis and makes the protocol experimentally less demanding ('fast addition' not required, tap water can be used in the final steps) as compared to previously reported procedures, without compromising the size and shape monodispersity of the product.

Universal Method for Producing Reduced Graphene Oxide/Gold Nanoparticles Composites with Controlled Density of Grafting and Long-Term Stability.

In this study, we report a universal approach allowing the non-covalent deposition of gold nanoparticles on reduced graphene oxide surface in a controlled fashion. We used a modified Hummers method to obtain graphene oxide, which then underwent surficial functionalization with carboxyl moieties coupled with simultaneous reduction. Nanoparticles were synthesized ex-situ and capped with a thiolated poly-ethylene glycol (PEG) ligand.

Energy Transfer from Photosystem I to Thermally Reduced Graphene Oxide.

The energy transfer from photosynthetic complex photosystem I to thermally reduced graphene oxide was studied using fluorescence microscopy and spectroscopy, and compared against the structure in which monolayer epitaxial graphene was used as the energy acceptor. We find that the properties of reduced graphene oxide (rGO) as an energy acceptor is qualitatively similar to that of epitaxial graphene. Fluorescence quenching, which in addition to shortening of fluorescence decay, is a signature of energy transfer varies across rGO substrates and correlates with the transmission pattern.