We describe the peculiar conditions under which optically driven gold nanoparticles (NPs) can significantly increase temperature or even melt a surrounding matrix. The heating and melting processes occur under light illumination and involve the plasmon resonance. For the matrix, we consider water, ice, and polymer. Melting and heating the matrix becomes possible if a nanoparticle size is large enough. Significant enhancement of the heating effect can appear in ensembles of NPs due to an increase of a volume of metal and electric-field amplification. Keywords Metal nanoparticles AE Heat generation AE PlasmonsThere has been a great deal of interest in recent years in the development of biosensors and actuators based on metal and semiconductor nanoparticles (NPs). Metal NPs can efficiently quench [1] or enhance [2] photoluminescence from attached quantum emitters. The latter has been demonstrated for bio-conjugates composed of Au NPs, linker molecules, and semiconductor nanocrystals. Metal (gold) NPs have useful thermal properties. Under optical illumination, Au NPs efficiently create heat [3][4][5][6][7][8]. The heating effect becomes especially strong under the plasmon resonance conditions when the energy of incident photons is close to the plasmon frequency of an Au NP. In recent papers, the heating effect in Au NPs was used for several purposes. The paper [3] reports imaging of proteins labeled with Au NPs in cells, using an all-optical method based on photo-thermal interference contrast. In the paper [4] the heating effect from gold NPs is used for biomedical applications. Another publication [5] described remote release of materials (drugs) from a capsule containing Au NPs excited with intense light. In the paper [7], the authors assembled a superstructure Au-NP-polymer-CdTe-NP with interesting thermal properties. Due to the exciton-plasmon interaction, the optical emission of such a superstructure is strongly temperature-dependent [7]. The study [8] characterized heat generation due to gold NPs at the nanoscale level through the observation of the melting process in the ice matrix. In particular, it was found in Ref. [8] that the heating process has a mesoscopic character and strongly depends on the geometry of a NP ensemble.Here we study theoretically the processes of heating and melting due to single Au NPs and NP complexes. We find the conditions and estimate the typical times to significantly increase the temperature of the surrounding material. Our estimations show that using accessible light intensities one can melt ice or polymer matrixes around a single Au NP. The polymer is very common in modern nanotechnology and has properties analogous to the biological matter. Therefore, our results can be useful to understand and design heating effects of Au NPs embedded into biological and living systems. The ice is a very convenient model system which can be easily prepared and controlled. This system can be used

Constructing ultralong organic phosphorescent materials possessing a high quantum yield is challenging. Herein, assemblies of purely organic supramolecular pins composed of alkyl‐bridged phenylpyridinium salts and cucurbit[8]uril (CB[8]) are reported. Different from “one host with two guests” and “head‐to‐tail” binding, the binding formation of supramolecular pins is “one host with one guest” and “head‐to‐head,” which overcomes electrostatic repulsion and promotes intramolecular charge transfer. The supramolecular pin 1/CB[8] displays afterglow with high phosphorescence quantum yield (99.38%) after incorporation into a rigid matrix, which is the highest yield reported to date for phosphorescent materials. Moreover, multicolor photoluminescence can be obtained by different excitation wavelengths and ratios of host to guest. Owing to the redshift of the absorption, the supramolecular pins are applied for targeted phosphorescence imaging of mitochondria. This work will provide a reasonable supramolecular strategy to achieve redshifted and efficient phosphorescence both in the solid state and in aqueous solution.

We report a novel strategy for the controlled synthesis of gold nanoparticles (AuNPs) with narrow size distribution (1.9 ± 0.4 nm) through NP nucleation and growth inside the cavity of a well-defined three-dimensional, shape-persistent organic molecular cage. Our results show that both a well-defined cage structure and pendant thioether groups pointing inside the cavity are essential for the AuNP synthesis.

The synthesis of discrete nanostructures with a strong, persistent, stable plasmonic circular dichroism (PCD) signal is challenging. We report a seed‐mediated growth approach to obtain discrete Au nanorods with high and stable chiroptical responses (c‐Au NRs) in the visible to near‐IR region. The morphology of the c‐Au NRs was governed by the concentration of l‐ or d‐cysteine used. The amino acids encapsulated within the discrete gold nanostructure enhance their PCD signal, attributed to coupling of dipoles of chiral molecules with the near‐field induced optical activity at the hot spots inside the c‐Au NRs. The stability of the PCD signal and biocompatibility of c‐Au NRs was improved by coating with silica or protein corona. Discrete c‐Au NR@SiO2 with Janus or core–shell configurations retained their PCD signal even in organic solvents. A side‐by‐side assembly of c‐Au NRs induced by l‐glutathione led to further PCD signal enhancement, with anisotropic g factors as high as 0.048.

Plasmonic motifs with precise surface recognition sites are crucial for assembling defined nanostructures with novel functionalities and properties. In this work, a unique and effective strategy is successfully developed to pattern DNA recognition sites in a helical arrangement around a gold nanorod (AuNR), and a new set of heterogeneous AuNR@AuNP plasmonic helices is fabricated by attaching complementary-DNA-modified gold nanoparticles (AuNPs) to the predesigned sites on the AuNR surface. AuNR is first assembled to one side of a bifacial rectangular DNA origami, where eight groups of capture strands are selectively patterned on the other side. The subsequently added link strands make the rectangular DNA origami roll up around the AuNR into a tubular shape, therefore giving birth to a chiral patterning of DNA recognition sites on the surface of AuNR. Following the hybridization with the AuNPs capped with the complementary strands to the capture strands on the DNA origami, left-handed and right-handed AuNR@AuNP helical superstructures are precisely formed by tuning the pattern of the recognition sites on the AuNR surface. Our strategy of nanoparticle surface patterning innovatively realizes hierarchical self-assembly of plasmonic superstructures with tunable chiroptical responses, and will certainly broaden the horizon of bottom-up construction of other functional nanoarchitectures with growing complexity.