Kinetically Controlled Seeded Growth Synthesis of Citrate-Stabilized Gold Nanoparticles of up to 200 nm: Size Focusing versus Ostwald Ripening

Abstract

Monodisperse citrate-stabilized gold nanoparticles with a uniform quasi-spherical shape of up to ∼200 nm and a narrow size distribution were synthesized following a kinetically controlled seeded growth strategy via the reduction of HAuCl(4) by sodium citrate. The inhibition of any secondary nucleation during homogeneous growth was controlled by adjusting the reaction conditions: temperature, gold precursor to seed particle concentration, and pH. This method presents improved results regarding the traditional Frens method in several aspects: (i) it produces particles of higher monodispersity; (ii) it allows better control of the gold nanoparticle size and size distribution; and (iii) it leads to higher concentrations. Gold nanoparticles synthesized following this method can be further functionalized with a wide variety of molecules, hence this method appears to be a promising candidate for application in the fields of biomedicine, photonics, and electronics, among others.

New Surface-Enhanced Raman Sensing Chip Designed for On-Site Detection of Active Ricin in Complex Matrices Based on Specific Depurination

“…Different sizes of citratestabilized AuNPs (∼60, ∼75, ∼90, and ∼100 nm) were prepared according to the kinetically controlled seeded growth method. 24 Their morphologies were characterized using transmission electron microscopy (TEM, JEOL model 1200EX) operated at an accelerating voltage of 100 kV. The extinction spectra of AuNPs was collected by a Shimadzu 3600 ultraviolet−visible−near infrared (UV−vis−NIR) spectrometer.…”

A Metal Chelator as a Plasmonic Signal‐Generation Superregulator for Ultrasensitive Colorimetric Bioassays of Disease Biomarkers

“…The majority of the available evidence in the literature suggests that currently used AuNPs as signal reporters or quenchers for assays are mostly fabricated by reduction of Au 3+ in the present of trisodium citrate at boiling temperature and with heating reflux equipment for several hours 13. This rigorous process obviously does not meet the requirement in an in situ signal‐generation mechanism.…”

The role of PEG conformation in mixed layers: from protein corona substrate to steric stabilization avoiding protein adsorption

“…Competing biconjugation of MUA and SH-PEG About 14.6 ± 1.5 nm AuNPs were synthesized in sodium citrate following a seeding growth approach as described in the literature [27] (Figure 1). This approach is based on a kinetically controlled growth of sodium citrate AuNPs, avoiding new NP nucleation, NP coalescence and instability (pH drop) during the growth process.…”

“…MUA-capped AuNPs were prepared and concentrated up to 2.4 Â 10 14 NP/mL (0.39 µM) in order to assay their stability in physiologic conditions at significant doses. Note that an AuNP concentration in common synthesis is 0.5-10 nM [27,41]. However, higher concentration of AuNPs is often required for in vivo and in vitro applications.…”