Multiphoton imaging of melanoma 3D models with plasmonic nanocapsules.

We report the synthesis of plasmonic nanocapsules and the cellular responses they induce in 3D melanoma models for their perspective use as a photothermal therapeutic agent. The wall of the nanocapsules is composed of polyelectrolytes. The inner part is functionalized with discrete gold nanoislands. The cavity of the nanocapsules contains a fluorescent payload to show their ability for loading a cargo. The nanocapsules exhibit simultaneous two-photon luminescent, fluorescent properties and X-ray contrasting ability. The average fluorescence lifetime (τ) of the nanocapsules measured with FLIM (0.3 ns) is maintained regardless of the intracellular environment, thus proving their abilities for bioimaging of models such as 3D spheroids with a complex architecture. Their multimodal imaging properties are exploited for the first time to study tumorspheres cellular responses exposed to the nanocapsules. Specifically, we studied cellular uptake, toxicity, intracellular fate, generation of reactive oxygen species, and effect on the levels of hypoxia by using multi-photon and confocal laser scanning microscopy. Because of the high X-ray attenuation and atomic number of the gold nanostructure, we imaged the nanocapsule-cell interactions without processing the sample. We confirmed maintenance of the nanocapsules' geometry in the intracellular milieu with no impairment of the cellular ultrastructure. Furthermore, we observed the lack of cellular toxicity and no alteration in oxygen or reactive oxygen species levels. These results in 3D melanoma models contribute to the development of these nanocapsules for their exploitation in future applications as agents for imaging-guided photothermal therapy. STATEMENT OF SIGNIFICANCE: The novelty of the work is that our plasmonic nanocapsules are multimodal. They are responsive to X-ray and to multiphoton and single-photon excitation. This allowed us to study their interaction with 2D and 3D cellular structures and specifically to obtain information on tumor cell parameters such as hypoxia, reactive oxygen species, and toxicity. These nanocapsules will be further validated as imaging-guided photothermal probes.

In Vitro Analysis of the Effects of ITER-Like Tungsten Nanoparticles: Cytotoxicity and Epigenotoxicity in BEAS-2B Cells.

Tungsten was chosen as a wall component to interact with the plasma generated by the International Thermonuclear Experimental fusion Reactor (ITER). Nevertheless, during plasma operation tritiated tungsten nanoparticles (W-NPs) will be formed and potentially released into the environment following a Loss-Of-Vacuum-Accident, causing occupational or accidental exposure. We therefore investigated, in the bronchial human-derived BEAS-2B cell line, the cytotoxic and epigenotoxic effects of two types of ITER-like W-NPs (plasma sputtering or laser ablation), in their pristine, hydrogenated, and tritiated forms. Long exposures (24 h) induced significant cytotoxicity, especially for the hydrogenated ones. Plasma W-NPs impaired cytostasis more severely than the laser ones and both types and forms of W-NPs induced significant micronuclei formation, as shown by cytokinesis-block micronucleus assay. Single DNA strand breaks, potentially triggered by oxidative stress, occurred upon exposure to W-NPs and independently of their form, as observed by alkaline comet assay. After 24 h it was shown that more than 50% of W was dissolved via oxidative dissolution. Overall, our results indicate that W-NPs can affect the in vitro viability of BEAS-2B cells and induce epigenotoxic alterations. We could not observe significant differences between plasma and laser W-NPs so their toxicity might not be triggered by the synthesis method.

Common Aspects Influencing the Translocation of SERS to Biomedicine.

This review overviews the impact in biomedicine of surface enhanced. Raman scattering motivated by the great potential we believe this technique has. We present the advantages and limitations of this technique relevant to bioanalysis in vitro and in vivo and how this technique goes beyond the state of the art of traditional analytical, labelling and healthcare diagnostic technologies.

Highly active nanoreactors: nanomaterial encapsulation based on confined catalysis.

It happens inside: highly active nanoreactors are prepared by encapsulating dendritic Pt nanoparticles (NPs) grown on a polystyrene template inside hollow porous silica capsules. The catalytic activity of these Pt NPs is preserved after encapsulation and template removal. Different metals, such as Ni, can thus be reduced inside the capsules, thereby leading to the formation of composites with tunable magnetic properties.

Design of SERS-encoded, submicron, hollow particles through confined growth of encapsulated metal nanoparticles.

The synthetic architectures of complex inorganic nanostructures, including multifunctional hollow capsules, are expected to play key roles in many different applications, such as drug delivery, photonic crystals, nanoreactors, and sensing. Implementation of novel strategies for the fabrication of such materials is needed because of the infancy of this knowledge, which still limits progress in certain areas. Herein we report a straightforward synthetic approach for the development of multifunctional submicron reactors comprising catalytic gold nanoparticles (2-3 nm) confined inside hollow silica capsules. Additionally, the confined growth of encapsulated metal nanoparticles was carried out to evidence the usefulness and functionality of these reactors in catalytic applications and as an approach for the development of novel complex nanostructures. Their potential and multifunctionality have been pointed out by fabrication of SERS-encoded submicrometer particles with shape and size uniformity for use in antigen biosensing; this was accomplished via codification of gold nanoparticle islands grown onto their inner surfaces.

Label-free SERS detection of relevant bioanalytes on silver-coated carbon nanotubes: The case of cocaine.

Surface-enhanced Raman scattering (SERS) spectroscopy can be used for the label-free determination and quantification of relevant small biometabolites that are hard to identify by conventional immunological methods, in the absence of labelling. In this work, detection is based on monitoring the vibrational changes occurring at a specific biointerface (a monoclonal antibody, mAb) supported on silver-coated carbon nanotubes (CNT@Ag). Engineered CNT@Ag play a key role, as they offer a stable substrate to support the biointerface, with a high density of hot spots. Proof of concept is demonstrated through the analysis and quantification of the main cocaine metabolite benzoylecgonine. These results open a new avenue toward the generation of portable sensors for fast ultradetection and quantification of relevant metabolites. The use of discrete particles (CNT@Ag@mAb) rather than rough films, or other conventional SERS supports, will also enable a safe remote interrogation of highly toxic sources in environmental problems or in biological fluids.

SERS study of the controllable release of nitric oxide from aromatic nitrosothiols on bimetallic, bifunctional nanoparticles supported on carbon nanotubes.

A hybrid system comprising bimetallic nanoparticles supported on carbon nanotubes (CNTs) was engineered to maximize the surface-enhanced Raman scattering signal from solution by generating a high density of hot spots with reproducible enhancing activity and long-term colloidal and optical stability. CNT@AgAu was employed as a bifunctional material to catalyze and monitor the controlled release of nitric oxide from aromatic nitrosothiols, as a function of the gold content.