Abstract: Dendritic gold nanoparticles (Au NPs) were synthesized by reducing chloroauric acid (HAuCl4) with ascorbic acid in an aqueous solution of N-methyl-N-dodecylpiperidinium bromide (C12PDB). Transmission electron microscopic (TEM) images showed that the dendritic Au NPs, with good symmetry and multilevel branches, had a diameter of 3.5–4 μm. When surface-enhanced Raman substrates (SERS) were used to detect rhodamine 6G (R6G), these Au NPs showed excellent enhancement effect with an enhancement factor of about 105. These SERS substrates showed high sensitivity with a minimum detectable concentration of R6G as low as 3 × 10-9 mol/L. The SERS substrates based on these dendritic Au NPs also showed good signal repeatability with relative standard deviation (RSD) lower than 10% (n = 10). The dendritic Au NPs substrates afforded limits of detection (LOD) around 1 × 10-8 mol/L for aqueous malachite green (MG) solutions. These Au NPs were successfully applied to rapidly detect MG in Carassius auratus samples. The recoveries of MG were 81.6%–102.1% in the spiked samples.

Key words: N-methyl-N-dodecylpiperidinium bromide; dendritic gold nanoparticles; surface-enhanced Raman spectroscopy; malachite green