Easy colorimetric detection of gadolinium ions based on gold nanoparticles: key role of phosphine-sulfonate ligands

Abstract

The possibility to easily and rapidly assess the presence of Gd3+ ions in solution is of paramount importance in many domains like magnetic resonance imaging. In that context, the use...

A Charge‐Switchable Zwitterionic Peptide for Rapid Detection of SARS‐CoV‐2 Main Protease

“…Second, the nanoparticles are colloidally stable in various media due to the effective phosphorus-togold coordination, large steric hindrance from the bulky aromatic rings, and strong electrostatic double layer repulsions. [22] BSPP-capped AuNPs have a compact ligand layer and thus favor tight interparticle interactions, e.g., the hydrodynamic diameter (D H ) is 19.1 nm with a PDI of 0.10 (Figure S1). [23] More characterizations of the ligand exchange and the resulting particles such as TEM, DLS, UV/ Vis, and 1 H NMR are given in Figure S1.…”

“…First, the BSPP ligand is rich in terminal sulfonate groups and thus gives the nanoparticle strong negative charges, i.e., the zeta potentials ( ζ ) are −26.5±1.5 mV. Second, the nanoparticles are colloidally stable in various media due to the effective phosphorus‐to‐gold coordination, large steric hindrance from the bulky aromatic rings, and strong electrostatic double layer repulsions [22] . BSPP‐capped AuNPs have a compact ligand layer and thus favor tight interparticle interactions, e.g., the hydrodynamic diameter ( D H ) is 19.1 nm with a PDI of 0.10 (Figure S1) [23] .…”

Key Features of Bolaamphiphile Structures for the Synthesis, Stabilization, and Catalytic Properties of Gold Nanoparticles

“…where FP max represents the plateau value and τ F is a characteristic time describing the kinetics of the absorption changes. 20 For each family of bolaamphiphiles comprising a C 12 alkyl chain, different solutions were prepared for the range of pH from 2 to 12 while keeping the concentration of gold and For each solution, the FP max was determined as previously described. Figure 2B depicts the evolution of the FP max as a function of pH for bolaamphiphiles used as a coating agent comprising 12 atoms of carbon (C 12 ) with different polar heads but a constant bolaamphiphile concentration.…”

“…In order to analyze quantitatively these results, a semiempirical flocculation parameter (FP) was calculated . The latter was measured from normalized spectra by calculating the integration between 600 and 800 nm from which the integrated absorption for pristine AuNPs was subtracted (see Section IV.2 and Figure S6 in the SI). − The normalization step enables us to get rid of the decantation phenomenon. For a given solution, the FP increases through time to reach a plateau.…”

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“…Commercial samples as well as self-grown unpurified AuNP samples contain unwanted impurities and salts, which would impede the electrospray injection and not giving consistent size distributions with different flow rates. Citrate-capped AuNPs were ligand exchanged with bis(p-sulfonatophenyl)phenylphosphine dihydrate dipotassium salt (BSPP) (Sigma-Aldrich), to avoid aggregation at high concentration and different conditions like repeated centrifugation during the purification [5]. Phosphine coating increases the overall negative charge of the particles and thus increases the stability of particles at a range of buffer conditions.…”