Ultrafine Selective Metal-Complexing Nanoparticles:  Synthesis by Microemulsion Copolymerization, Binding Capacity, and Ligand Accessibility

Abstract

Stable translucent aqueous suspensions of ligand-functionalized nanoparticles, with average diameters ranging from 12 to 20 nm and containing from 0.25 to up to 0.75 mmol of ligand/g, are readily obtained by copolymerization in oil-in-water microemulsions of a polymerizable tetraaza macrocycle, vinylbenzylcyclam (cyclam: 1,4,8,11-tetraazacyclotetradecane). These nanoparticles exhibit a very high selectivity for cupric ions with binding capacities of up to 0.65 mmol of Cu/g as well as a remarkable ligand accessibility, deduced from spectrophotometric titration, with about 75% of the cyclam residues located near the surface for nanoparticles in the 12-13 nm range. Core-shell bimetallic nanoparticles are obtained by cation exchange. The cyclam-functionalized nanoparticles are comparable to highgeneration PAMAM dendrimers in their ability to complex metals.

Boronic acid-functionalized nanoparticles: synthesis by microemulsion polymerization and application as a re-usable optical nanosensor for carbohydrates

“…Remarkably, the color change occurs instantaneously under conditions close to stoichiometry thus demonstrating the accessibility of the boronic acid receptors grafted to nanoparticles. A similar solutionlike behavior has already been observed for metal-complexing nanoparticles [3,4]. As can be seen in Fig.…”

“…Copolymerization of vinylbenzylchloride (15 mol%, 1.22 mmol/g of monomers) with styrene and divinylbenzene as a cross-linking agent is performed in the presence of a radical photo-initiator DMPA (2,2-dimethoxy-2-phenylacetophenone) solubilized within the monomers oil phase [3,4,14,15]. Polymerization readily takes place at room temperature under white light irradiation and leads to a stable, translucent, slightly bluish, colloidal aqueous suspension of nanoparticles NL-CH 2 X (Fig.…”

“…In this context, aqueous suspensions of functionalized polymer nanoparticles, so called 'nanolatexes', hold most promise for the development of new polymer supports with improved reagent activity [2][3][4]. In life science, polymer nanoparticles have been found to provide valuable supports for the design of carriers, sensors or probes that are suitable for intracellular transport and local measurements [5][6][7][8][9].…”

“…with diameter smaller than 30 nm), nanolatexes, which exhibit very large specific areas (larger than 300 m 2 /g) and high surface functionality [2][3][4][10][11][12][13][14][15]. The colloidal stability is another outstanding feature of nanolatexes since, under appropriate conditions, microemulsion polymerization leads to very stable and transparent suspensions.…”

“…Nanolatexes are therefore valuable supports for the design of novel devices for optical sensing since qualitative and quantitative analyses can be readily achieved by classical spectroscopic methods [3][4][5]. Although the technique of polymerization in microemulsion is now well documented, a limited number of contributions have dealt with the synthesis of functionalized nanoparticles [2][3][4][12][13][14][15][16]. Consequently, there is a great demand for synthetic approaches that allow the preparation of welldefined nanoparticles that possess chemical or biological functionalities like specific ligands or receptors.…”