The Interaction of Amines with Gold Nanoparticles.

Understanding the interactions between amines and the surface of gold nanoparticles is important because of their role in the stabilization of the nanosystems, in the formation of the protein corona, and in the preparation of semisynthetic nanozymes. By using fluorescence spectroscopy, electrochemistry, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and molecular simulation, a detailed picture of these interactions is obtained. Herein, it is shown that amines interact with surface Au(0) atoms of the nanoparticles with their lone electron pair with a strength linearly correlating with their basicity corrected for steric hindrance.

Exploiting multivalency and cooperativity of gold nanoparticles for binding phosphatidylinositol (3,4,5)-trisphosphate at sub-nanomolar concentrations.

Cationic, monolayer-protected gold nanoparticles provide a multivalent charged surface and a hydrophobic monolayer that synergistically contribute to the binding of phosphatidylinositol (3,4,5)-trisphosphate, a relevant biomarker. The observed dissociation constant is in the picomolar region, providing the possibility of using these gold nanoparticles for the selective extraction of this molecule from biological fluids.

Formation of Catalytic Hotspots in ATP-Templated Assemblies.

The self-assembly of surfactant-based structures that rely for their formation on the combination of a thermodynamically controlled and a dissipative pathway is described. Adenosine triphosphate (ATP) acts as a high-affinity template and triggers assembly formation at low surfactant concentrations. The presence of these assemblies creates the conditions for the activation of a dissipative self-assembly process by a weak-affinity substrate.

On the Metal-Aided Catalytic Mechanism for Phosphodiester Bond Cleavage Performed by Nanozymes.

Recent studies have shown that gold nanoparticles (AuNPs) functionalized with Zn(II) complexes can cleave phosphate esters and nucleic acids. Remarkably, such synthetic nanonucleases appear to catalyze metal (Zn)-aided hydrolytic reactions of nucleic acids similar to metallonuclease enzymes. To clarify the reaction mechanism of these nanocatalysts, here we have comparatively analyzed two nanonucleases with a >10-fold difference in the catalytic efficiency for the hydrolysis of the 2-hydroxypropyl-4-nitrophenylphosphate (HPNP, a typical RNA model substrate).

The Biotin-Avidin Interaction in Biotinylated Gold Nanoparticles and the Modulation of Their Aggregation.

The biotin-avidin interaction is used as a binding tool for the conjugation of biomolecules for more diverse applications; these include nanoparticle conjugation. Despite this, a thorough investigation on the different aggregates that may result from the interaction of biotinylated nanoparticles (gold nanoparticles, AuNPs, in this work) with avidin has not been carried out so far. In this paper, we address this problem and show the type of aggregates formed under thermodynamic and kinetic control by varying the biotinylated AuNP/avidin ratio and the order of addition of the two partners.