Dual-Mode Nanoprobes Based on Lanthanide Doped Fluoride Nanoparticles Functionalized by Aryl Diazonium Salts for Fluorescence and SERS Bioimaging

The design of dual-mode fluorescence and Raman tags stimulates a growing interest in biomedical imaging and sensing applications as they offer the possibility to synergistically combine the versatility and velocity of fluorescence imaging with the specificity of Raman spectroscopy. Although lanthanide-doped fluoride nanoparticles (NPs) are among the most studied fluorescent nanoprobes, their use for the development of bimodal fluorescent-Raman probes has never been reported yet, to the best of the authors knowledge, probably due to the difficulty to functionalize them with Raman reporter groups. This gap is filled herein by proposing a fast and straightforward approach based on aryl diazonium salt chemistry to functionalize Eu3+ or Tb3+ doped CaF2 and LaF3 NPs by Raman scatters. The resulting surface-enhanced Raman spectroscopy (SERS)-encoded lanthanide-doped fluoride NPs retain their fluorescence labeling capacity and display efficient SERS activity for cell bioimaging. The potential of this new generation of bimodal nanoprobes is assessed through cell viability assays and intracellular fluorescence and Raman imaging, opening up unprecedented opportunities for biomedical applications.

Experimental and theoretical evidence for oriented aggregate crystal growth of CoO in a polyol

CoO submicrometer-sized pseudo-single crystals were produced in polyol thanks to an oriented aggregation crystal growth driven by the polyol molecules themselves.

Correction: Haj-Khlifa, S., et al. Polyol Process Coupled to Cold Plasma as a New and Efficient Nanohydride Processing Method: Nano-Ni2H as a Case Study. Nanomaterials 2020, 10, 136

The authors wish to make the following corrections to this paper [1]: there are two mistakes inthis article [1] [...].

The polyol process: a unique method for easy access to metal nanoparticles with tailored sizes, shapes and compositions

After about three decades of development, the polyol process is now widely recognized and practised as a unique soft chemical method for the preparation of a large variety of nanoparticles which can be used in important technological fields. It offers many advantages: low cost, ease of use and, very importantly, already proven scalability for industrial applications. Among the different classes of inorganic nanoparticles which can be prepared in liquid polyols, metals were the first reported. This review aims to give a comprehensive account of the strategies used to prepare monometallic nanoparticles and multimetallic materials with tailored size and shape. As regards monometallic materials, while the preparation of noble as well as ferromagnetic metals is now clearly established, the scope of the polyol process has been extended to the preparation of more electropositive metals, such as post-transition metals and semi-metals. The potential of this method is also clearly displayed for the preparation of alloys, intermetallics and core-shell nanostructures with a very large diversity of compositions and architectures.

Electrode surface confinement of self-assembled enzyme aggregates using magnetic nanoparticles and its application in bioelectrocatalysis

Self-assembled enzyme aggregates, prepared from magnetic iron oxide nanoparticles, avidin, and a biotinylated redox enzyme, were shown particularly useful for the simple, fast, and efficient construction of highly enzyme-loaded electrodes with the help of a magnet. The approach was illustrated in the case of the bioelectrocatalytic oxidation of NADH by a diaphorase oxidoreductase in the presence of a ferrocene mediator. Two different self-assembling procedures were tested, taking advantage of the spontaneous aggregation of the nanoparticles in the presence of avidin and also of the multivalency binding of biotinylated diaphorase toward avidin. Activities of the bound and unbound diaphorase were systematically controlled allowing determination of the number of active biotinylated diaphorase per nanoparticle incorporated within each magnetic enzyme aggregate. An active enzyme loading capacity of up to 2.35 nmol mg-1 was found for the best nanostructured enzyme assembly, which is 200 times better than for commercialized magnetic micrometer-sized beads coated with streptavidin and saturated with diaphorase. With the help of a permanent magnet, the magnetic enzyme aggregates were finally magnetically collected as a film on the surface of a small screen-printed carbon electrode and the catalytic currents recorded by cyclic voltammetry. From the analysis of the steady-state catalytic current responses and the kinetic rate constants of biotinylated diaphorase, it was possible to determine the enzyme concentration within the magnetic films. Owing to the high enzyme loading in the aggregates of nanoparticles (i.e., 130 microM), the catalytic current responses were definitely higher than the ones measured at an electrode coated with a closed-packed monolayer of diaphorase or at an electrode covered with a film of magnetic micrometer-sized streptavidin beads saturated with diaphorase.