Magneto-Plasmonic Colloidal Nanoparticles Obtained by Laser Ablation of Nickel and Silver Targets in Water

Abstract

Stable magneto-plasmonic nanoparticles in colloidal suspensions are fabricated by two-step nanosecondpulsed laser ablation of nickel and silver targets in pure water and characterized by UV−visible absorption, Raman, X-ray photoelectron spectroscopic, and magnetic measurements, along with high-resolution electron microscopy analysis. These systems are constituted by a low-crystallinity matrix of ferromagnetic nickel hydroxide, where nickel oxide nanocrystals are embedded, with silver nanoparticles intimately linked to them. The surface enhanced Raman scattering activity is assessed by adsorption of adenine as probe ligand. Spectroscopic investigation and density functional theory calculations revealed that adenine is linked to nickel oxide, while nanosilver essentially plays the role of ensuring the Raman enhancement for the adsorbed organic ligand. Both magnetic and plasmonic properties allow using these nanostructured bimetallic platforms as catalysts in chemical reactions or nanosensors in biomedicine as well as in environmental research.

Pulsed laser ablation and incubation of nickel, iron and tungsten in liquids and air

“…Laser ablation of metals in liquids enables the insitu study of corrosion and repassivation processes [3,4] as well as the production of biocompatible nanoparticles for medical and catalytic applications [5][6][7]. The pulsed laser generation of colloidal metal nanoparticles (e.g., Ag, Au, Pt, Pd, Cu, Fe, Ni, W) in distilled water and organic solvents attracted much attention in the past two decades [7][8][9][10][11][12][13][14][15][16][17]. The complex mechanism of laser ablation in liquids involves a series of steps extended over many orders of magnitude in time and involving ablation, plasma expansion inside a cavitation bubble, the penetration of condensed nano-sized phases into the liquid, as well as secondary beam-colloid interaction [18][19][20].…”

Spectroscopic and Microscopic Analyses of Fe3O4/Au Nanoparticles Obtained by Laser Ablation in Water

“…Unlike the mixed Ag/Fe 3 O 4 and Ag/NiO colloids previously prepared by two-step laser ablation [23,24], the present magneto-plasmonic nanoparticles are more biocompatible and are therefore potentially useful not only in the field of sensors, but also for biomedical applications. Our bimetallic colloidal suspensions are expected to have very low toxicity.…”

“…A scaling factor of 0.98 for the calculated harmonic wavenumbers was employed, as usually performed in calculations at this level of theory [34][35][36][37][38]. The calculated Raman intensities were obtained by following the indications of reference [24].…”

“…The presence of iron oxide gives the bimetallic colloid new possibilities of adsorption in addition to those inherent to gold nanoparticles, especially regarding organic pollutants and heavy metals, allowing to remove them from the aqueous environment by applying a magnetic field. Moreover, these nanoparticles, thanks to their low toxicity, are potentially useful not only in the field of sensors, but also for biomedical applications.Nanomaterials 2020, 10, 132 2 of 13 of iron and silver [23] and of nickel and silver [24] were employed to obtain magneto-plasmonic colloidal nanoparticles.Here, we propose the fabrication of bifunctional Fe 3 O 4 /Au nanoparticles obtained by the two-step laser ablation of iron and gold targets in water, along with microscopic and spectroscopic characterization. To this end, high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) analyses have been performed, and visible absorption, XPS, Raman, and SERS spectra have been obtained.…”

“…Nanomaterials 2020, 10, 132 2 of 13 of iron and silver [23] and of nickel and silver [24] were employed to obtain magneto-plasmonic colloidal nanoparticles.…”