An integrated approach for trace detection of pollutants in water using polyelectrolyte functionalized magneto-plasmonic nanosorbents.

Resistance of pathogenic micro-organisms to conventional antibiotics is an essential issue for public health. The presence of such pharmaceuticals in aquatic ecosystems has been of major concern for which remediation and ultra-sensitive monitoring methods have been proposed. A less explored strategy involves the application of multifunctional nanosorbents for the uptake and subsequent detection of vestigial contaminants.

Magnetite-Supported Gold Nanostars for the Uptake and SERS Detection of Tetracycline.

Magnetite nanoparticles (MNPs) decorated with gold nanostars (AuNSs) have been prepared by using a seed growth method without the addition of surfactants or colloidal stabilizers. The hybrid nanomaterials were investigated as adsorbents for the uptake of tetracycline (TC) from aqueous solutions and subsequent detection using surface-enhanced Raman scattering (SERS). Several parameters were investigated in order to optimize the performance of these hybrid platforms on the uptake and SERS detection of TC, including variable pH values and the effect of contact time on the removal of TC.

Ferromagnetic sorbents based on nickel nanowires for efficient uptake of mercury from water.

This work reports the preparation of ferro-magnetic nickel nanowires (NiNW) coated with dithiocarbamate-functionalized siliceous shells and its application for the uptake of aqueous Hg(II) ions by magnetic separation. NiNW with an average diameter and length of 35 nm and 5 μm, respectively, were firstly prepared by Ni electrodeposition in an anodic aluminum oxide template. The NiNW surfaces were then coated with siliceous shells containing dithiocarbamate groups via a one-step procedure consisting in the alkaline hydrolytic co-condensation of tetraethoxysilane (TEOS) and a siloxydithiocarbamate precursor (SiDTC).

Functionalization of nickel nanowires with a fluorophore aiming at new probes for multimodal bioanalysis.

This work reports research on the development of bimodal magnetic and fluorescent 1D nanoprobes. First, ferromagnetic nickel nanowires (NiNW) have been prepared by Ni electrodeposition in an anodic aluminum oxide (AAO) template. The highly ordered self-assembled AAO nanoporous templates were fabricated using a two-step anodization method of aluminum foil.

Fluorescent Magnetic Bioprobes by Surface Modification of Magnetite Nanoparticles.

Bimodal nanoprobes comprising both magnetic and optical functionalities have been prepared via a sequential two-step process. Firstly, magnetite nanoparticles (MNPs) with well-defined cubic shape and an average dimension of 80 nm were produced by hydrolysis of iron sulfate and were then surface modified with silica shells by using the sol-gel method. The Fe₃O₄@SiO₂ particles were then functionalized with the fluorophore, fluorescein isothiocyanate (FITC), mediated by assembled shells of the cationic polyelectrolyte, polyethyleneimine (PEI).

Composite blends of gold nanorods and poly(t-butylacrylate) beads as new substrates for SERS.

Polymer based composites containing metal nanoparticles are shown to provide new substrates for SERS detection and simultaneously enable the development of new tools for molecular sensing. A very important aspect on the use of hybrid materials relates to the observation of synergistic effects that result from the use of distinct components such as a polymer and metal nanoparticles. We report here the preparation of new SERS substrates made from blends of colloidal Au (nanospheres and nanorods) and PtBA (poly(t-butylacrylate)).

SERS study on adenine using a Ag/poly(t-butylacrylate) nanocomposite.

Enhancement of Raman signals of the nucleobase adenine on an Ag based composite was studied using the 1064 nm laser line. The composite comprise emulsions of Ag nanoparticles encapsulated in poly(t-butylacrylate) (PtBA) beads that act as substrate for the Surface-Enhanced Raman Scattering (SERS) of adenine. For this system, Raman enhancement was observed for the ring-stretching vibrational mode of adenine after aggregation of the Ag/poly(t-butylacrylate) emulsion and isolation of the solid composite.