One-Phase Synthesis of Surface Modified Gold Nanoparticles and Generation of SERS Substrate by Seed Growth Method

Abstract

In this study, we report a novel and facile single-phase synthesis of stable AuNP-CTAB(NA) conjugates with good dispersibility, bearing a bilayer of cationic surfactant, cetyltrimethylammonium bromide (CTAB) supported by N-nonylamine (NA) as a cosurfactant. We investigated AuNP-CTAB(NA) conjugates by (1)H NMR spectroscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). These studies suggest the presence of a CTAB bilayer on the nanoparticles surface forming an admicelle and NA embedded in the hydrophobic core of that bilayer. AuNP-CTAB(NA) conjugates remain dispersed in water even in the presence of high concentrations of salt and over a wide range of solution pHs. These conjugates further grow bigger when treated with additional AuCl(4)(-), CTAB, and NA in the presence of the mild reducing agent, hydroquinone (HQ). The larger AuNP-CTAB(NA)-1 conjugates serve as SERS (surface-enhanced Raman Scattering) substrate of Raman active dye even at nanomolar concentrations.

One-step Synthesis of Cetyltrimethylammonium Bromide Stabilized Spherical Gold Nanoparticles

“…More recently, a cationic surfactant CTAB has been used for the synthesis of Au NPs. The CTAB stabilized Au NPs are superior than their citrate capped counterparts for various applications [12][13][14][15]. For instance, the inter-particle repulsive interaction owing to the positively charged bilayer of CTAB on particle surface prevents random disordered aggregation of NPs during solvent evaporation [12].…”

“…Therefore, uniform interparticle spacing equal to the length of CTAB molecule (2 nm) can be achieved on substrates making CTAB coated Au NPs excellent candidate for surface enhanced Raman spectroscopy [12]. The CTAB stabilized Au NPs also show excellent stability even under large salt concentration and low pH, whereas citrate capped Au NPs tend to agglomerate [15]. Furthermore, the synthesis of CTAB coated Au NPs can be carried out near room temperature which makes them economically viable for large scale production.…”

Highly electrostatically-induced detection selectivity and sensitivity for a colloidal biosensor made of chitosan nanoparticle decorated with a few bare-surfaced gold nanorods

“…Gold nanoparticles possess distinct physical and chemical properties that make them excellent building blocks for sensor synthesis with outstanding chemical and/or biological attributes (Boisselier and Astruc, 2009;Daniel and Astruc, 2004;Zayats et al 2005). They possess unique optoelectronic properties, high surface-to-volume ratio and compatibility with numerous functional ligands which make them tunable in responsiveness, such as plasmonic resonance absorption, conductivity, emission spectrum, etc, toward subtle change in surrounding environment (Haick, 2007;Baruah et al 2012;Nikoobakht and El-Sayed, 2003).…”

Multi-shaped cationic gold nanoparticle-l-cysteine-ZnSeS quantum dots hybrid nanozyme as an intrinsic peroxidase mimic for the rapid colorimetric detection of cocaine

“…For CTAB-AuNPs, the bands at 2915 cm -1 and 2847 cm -1 is assigned to the -C-H stretch while the bands at 1464 cm -1 is assigned to the -C-H bend. For the QDs-CTAB-AuNP hybrid nanozyme, the band at 1617 cm -1 which is absent in CTAB-AuNPs and the L-cyst-ZnSeS QDs can be used as a proof of the electrostatic interaction [38]. In addition, the -C-H { PAGE } bending and stretching band at 1460 cm -1 and 2913 cm -1 for the QDs-CTAB-AuNP hybrid nanozyme are shifted to lower wavenumbers relative to CTAB-AuNPs, thus tentatively confirming the established electrostatic interaction.…”