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The fabrication of highly luminescent, chemically stable and biocompatible small optical probes is of key interest in bioimaging. Herein we develop a multistep synthesis of hybrid superstructures that comprise quantum dot cores and dense layers of gold nanoparticles separated by a silica shell. This architecture allows for the versatile control of the QD–metal interactions by controlling the thickness of the dielectric spacer. The shell thickness is optimized at the nanometer scale in order to increase the enhanced photoluminescence. Further characterization of the emission in the single particle regime shows that our brighter particles require smaller acquisition times to yield better imaging results.

Coupling of localized surface plasmon resonances results in singular effects at the void space between noble metal nanoparticles. However, implementation of practical applications based on plasmon coupling calls for the high yield production of metal nanoparticle clusters (dimers, trimers, tetramers, …) with small gaps. Therefore, controlled assembly using colloid chemistry methods is an emerging and promising field. We present a brief overview over the controlled assembly of plasmonic nanoparticle clusters by colloid chemistry methods, together with a description of their plasmonic properties and some applications, with an emphasis in sensing through surface-enhanced Raman scattering spectroscopy for bio-detection purposes. We point out the important role of separation methods to obtain colloidal clusters in high yield. A special encouragement to explore assembly of anisotropic building blocks is pursued.

Gold nanostars can easily undergo reshaping into spherical particles by simply adding a small amount of CTAB. Such reshaping can be understood in terms of Ostwald ripening involving dissolution of weakly bound surface atoms at areas with high convex curvature and re-deposition at concave areas. This process can be stopped at any time by adding silver ions, which block bromide and stabilize the surface. Because the localized surface plasmon resonance (LSPR) band of the nanostars colloid gradually changes during etching, stabilization of intermediate morphologies allows fine LSPR tuning, which can be exploited for plasmonic applications.

We present in this review article an overview of the capabilities of surface enhanced Raman scattering (SERS) spectroscopy as a technique for applications related to environmental analysis and monitoring, ranging from the structural characterization of soils, through ultrasensitive detection of pollutants and heavy metal ions, to the analysis of plants, tissues and microorganisms, with a critical approach in which the drawbacks and difficulties associated to the various experimental configurations and enhancing substrates are introduced, as well as perspectives in the different fields.

SERS substrates were fabricated through self-assembly of gold nanoparticles upon solution-drying in a periodic confining structure. The technique leads to uniform, parallel linear nanoparticle arrays with the precise arrangement defined through the dimensions of the particles and the grooves, which provide high and uniform SERS enhancement over extended areas.

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Novel stable crystalline bimetallic silver–gold nanostructures homogeneously dispersed on Nafion were prepared by galvanic substitution of a vacuum evaporated silver island film with gold. The method allows control of the composition of the bimetallic nanostructures and tuning of optical properties. Formation of the nanoalloy was monitored by UV-Vis absorption, SEM-EDX, XRD, AFM, ATR-FTIR, and Raman scattering. Bimetallic nanostructure growth was monitored by UV-Vis absorption and surface-enhanced Raman scattering (SERS), by casting an aliquot from a dilute solution of 2-naphthalenethiol (2-NAT) on the composite surface. SERS intensity increases with galvanic substitution, reaching a maximum, and providing a material that delivers SERS enhancement several times higher than those obtained with regular silver and gold island films. Optical enhancement is also fairly homogeneous throughout the treated Nafion surface; this is demonstrated by mapping the average SERS intensity of a mixed Langmuir–Blodgett monolayer bis(benzimidazo)perylene and stearic acid excited with 514 and 633 nm laser lines.

The size and shape of nanoparticles can be controlled by varying the pH and concentration of the fulvic acid (FA) colloidal solution. FA thin solid films with embedded Au nanoparticles have been fabricated, and their optical field enhancing properties tested in surface-enhanced Raman scattering (SERS). High-resolution transmission electron microscopy data indicated that the size of nanoparticles ranges from 4 to 15 nm for films obtained at pH 11 and 8. At pH 5, however, hexagonal and triangular particles of ∼50 nm and truncated triangles of ∼200 nm are produced with a high concentration of fulvic acid (250 mg L−1). The number and size of truncated triangles can be diminished by decreasing the concentration of FA in the colloidal solution. This unprecedented control of size and shape was preserved in thin solid FA films embedding the gold nanoparticles. The plasmon-assisted enhancing optical properties are demonstrated by SERS of 2-naphthalenethiol, an analyte with a well defined SERS spectrum.

This is the peer reviewed version of the following article: C. Carrillo-Carrión, R. Martínez, M. F. Navarro Poupard, B. Pelaz, E. Polo, A. Arenas-Vivo, A. Olgiati, P. Taboada, M. G. Soliman, Ú. Catalán, S. Fernández-Castillejo, R. Solà, W. J. Parak, P. Horcajada, R. A. Alvarez-Puebla, P. del Pino, Angew. Chem. Int. Ed. 2019, 58, 7078, which has been published in final form at https:// doi.org/10.1002/anie.201902817. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions A plasmonic core–shell gold nanostar/zeolitic‐imidazolate‐framework‐8 (ZIF‐8) nanocomposite was developed for the thermoplasmonic‐driven release of encapsulated active molecules inside living cells. The nanocomposites were loaded, as a proof of concept, with bisbenzimide molecules as functional cargo and wrapped with an amphiphilic polymer that prevents ZIF‐8 degradation and bisbenzimide leaking in aqueous media or inside living cells. The demonstrated molecule‐release mechanism relies on the use of near‐IR light coupled to the plasmonic absorption of the core gold nanostars, which creates local temperature gradients and thus, bisbenzimide thermodiffusion. Confocal microscopy and surface‐enhanced Raman spectroscopy (SERS) were used to demonstrate bisbenzimide loading/leaking and near‐IR‐triggered cargo release inside cells, thereby leading to DNA staining This work has received financial support from the MINECO‐Spain (MAT2016‐80266‐R, MAT2015‐74381‐JIN, CTQ2017‐88648R, ENE2016‐79608‐C2‐1‐R, CTQ2017‐89588‐R, RYC‐2014‐15039, RYC‐2014‐16962), the Xunta de Galicia, Centro singular de investigación de Galicia accreditation 2016–2019 (ED431G/09), the Agrupación Estratégica de Materiales Action (ED431E 2018/08), the Generalitat de Cataluña (2017SGR522, 2017SGR883, SLT002/16/00239), the URV (2017PFR‐URV‐B2‐02), the German Research Society (DFG PA 794‐21‐1), and the European Union (European Regional Development Fund—ERDF, H2020‐MSCA‐IF‐2016, project 749667). M.F.N.P acknowledges the CONACYT PhD fellowship program SI

Metal nanoparticles are of great importance in the fabrication of new nanocomposite materials. One area of increasing interest is the application of metal nanoparticles (NP) as substrates for surface enhanced Raman scattering (SERS). In this regard, self-assembled monolayers (SAMs) of sulfur containing organic compounds are ideal target for SERS studies due to the strong affinity of sulfur for noble metals. Two types of molecules were synthesized for this study, an organic-soluble and a water-soluble styrene derivative. Self-assembling behaviors of these monomers on gold or silver nanostructured surfaces at room temperature were studied by UV-Vis spectroscopy, dynamic light scattering (DLS), SERS spectroscopy, and scanning electron microscopy (SEM). It was found that the interaction between sulfur compounds and metal NPs is strongly dependent on the NP size and the monomer environment. The hydrophilic NP surface switches to hydrophobic upon binding of sulfur-containing monomers, which leads to the formation of aggregates in aqueous solution for both water-soluble and oil-soluble monomers. The self-assembling behavior of these monomers on the metallic surface was compared with that of the corresponding homopolymers. Due to macromolecular and steric effects, the binding interaction between homopolymer and metal NP is weaker than that between NP and monomers. Surface polymerization of these monomers on metallic surfaces was observed as supported by SERS. Core-shell nanoparticles could also be obtained through seeded emulsion polymerization, but a decrease in SERS activity was observed.