Simultaneous Local Heating/Thermometry Based on Plasmonic Magnetochromic Nanoheaters.

A crucial challenge in nanotherapies is achieving accurate and real-time control of the therapeutic action, which is particularly relevant in local thermal therapies to minimize healthy tissue damage and necrotic cell deaths. Here, a nanoheater/thermometry concept is presented based on magnetoplasmonic (Co/Au or Fe/Au) nanodomes that merge exceptionally efficient plasmonic heating and simultaneous highly sensitive detection of the temperature variations. The temperature detection is based on precise optical monitoring of the magnetic-induced rotation of the nanodomes in solution. It is shown that the phase lag between the optical signal and the driving magnetic field can be used to detect viscosity variations around the nanodomes with unprecedented accuracy (detection limit 0.0016 mPa s, i.e., 60-fold smaller than state-of-the-art plasmonic nanorheometers). This feature is exploited to monitor the viscosity reduction induced by optical heating in real-time, even in highly inhomogeneous cell dispersions. The magnetochromic nanoheater/thermometers show higher optical stability, much higher heating efficiency and similar temperature detection limits (0.05 °C) compared to state-of-the art luminescent nanothermometers. The technological interest is also boosted by the simpler and lower cost temperature detection system, and the cost effectiveness and scalability of the nanofabrication process, thereby highlighting the biomedical potential of this nanotechnology.

Simple Synthesis of Biocompatible Stable CeO2 Nanoparticles as Antioxidant Agents.

Cerium oxide (IV) nanoparticles offer a high redox ability, while maintaining nontoxicity and high stability. Thus, dispersed nanoceria is a promising candidate as antioxidant material for human cells. In this work, we report on a fast and simple one-pot process that yield a final nanoparticle size of 2-4 nm in polar solvents such as water and alcohols. High boiling point solvents, namely, benzyl alcohol and triethylene glycol, are used to obtain high crystalline nanoparticles by thermal and microwave activation. Transmission electron microscopy investigations prove the narrow size distribution of the CeO2 nanoparticles and show that the shape can be tuned from spherical to cubic using an appropriate precursor. The main objective of this work is to produce nanoparticles, which are well-defined, biocompatible, and stable in highly concentrated colloidal solutions (up to 90 mM) for a long period of time to study their behavior as antioxidant agents in human cells under oxidative stress.

Annexin-V/quantum dot probes for multimodal apoptosis monitoring in living cells: improving bioanalysis using electrochemistry.

There is a great demand to develop novel techniques that allow useful and complete monitoring of apoptosis, which is a key factor of several diseases and a target for drug development. Here, we present the use of a novel dual electrochemical/optical label for the detection and study of apoptosis. We combined the specificity of Annexin-V for phosphatidylserine, a phospholipid expressed in the outer membrane of apoptotic cells, with the optical and electrochemical properties of quantum dots to create a more efficient label. Using this conjugate we addressed three important issues: (i) we made the labeling of apoptotic cells faster (30 min) and easier; (ii) we fully characterized the samples by common cell biological techniques (confocal laser scanning microscopy, scanning electron microscopy and flow cytometry); and (iii) we developed a fast, cheap and quantitative electrochemical detection method for apoptotic cells with results in full agreement with those obtained by flow cytometry.