Hyperbranched Au Nanocorals for SERS Detection of Dye Pollutants

Abstract

Gold (Au) nanomaterials having branched morphologies are recently attracting interest as surface-enhanced Raman scattering (SERS) substrates due to the abundance of hot spot regions in their structures. However, they are typically prepared through laborious experimental protocols that often make use of hazardous and expensive chemical reagents. In this study, we explored the use of environmentally compatible and low-cost organic acids that are known to occur naturally in plants (e.g., ascorbic acid, oxalic acid, tartaric acid) as alternative reagents to render the process greener. Aside from being environmentally friendly, the methodology presented here is convenient, direct, rapid, and inexpensive. The synthesis can be carried out in aqueous media at ambient conditions, does not require complicated setups, and the entire experimental procedure can be completed in less than an hour. Different organic acid combinations were tested, and it was found that the combination of ascorbic acid and oxalic acid can lead to the formation of hyperbranched Au nanocorals with distinct and extensive branching. Investigation of the formation mechanism revealed that the nanocorals are formed through a series of aggregation stages that begins with a one-dimensional (1D) assembly of branched Au nanoparticles, followed by aggregative growth into more expanded branched structures, which further merge to produce a densely packed three-dimensional (3D) network of nanocorals. The numerous tips and junctions in these hyperbranched nanocorals are plasmonic hot spots that allow for the SERSbased detection of rhodamine 6G, a toxic organic dye pollutant.

Design, Fabrication, and Applications of SERS Substrates for Food Safety Detection: Review

“…For instance, after Kneipp first used colloidal silver nanoparticle solution to detect a single R6G molecule in 1997 [ 101 ], subsequent studies have demonstrated the achievement of single-molecule detection using nanometal colloids. As a result, ongoing efforts focus on the development of metal nanoparticles, including different shapes of MNPs [ 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 ], composite materials of MNPs [ 111 , 112 , 113 , 114 , 115 ], and the modified MNPs [ 116 , 117 , 118 ].…”

“…Currently, various shapes of metal MNPs have been proposed, including the nanorods [ 111 , 116 ], nanostars [ 109 ], nanocubes [ 110 ], hyperbranched Au nanocorals [ 102 ], flower-like Au NPs [ 103 ], Pt-Au triangular nanoprisms [ 104 ], Au popcorns [ 105 ], decahedral Ag NPs [ 106 ], Au nanofoams [ 107 ], and dual-gap Au nanodumbbells [ 108 ]. These different shapes are aimed at creating more branches, pores, or tips on the MNPs, which are believed to generate high-intensity electromagnetic regions, also known as anisotropic hot spots.…”

Polyacrylonitrile as a versatile matrix for gold nanoparticle-based SERS substrates

“…[9][10][11][12][13][14][15][16] Gold nanoparticles (AuNPs) have been widely employed in SERS substrates because of their exceptional plasmonic properties, high chemical stability, and ease of functionalization. [17][18][19][20][21][22][23] LSPR is one of their unique optical properties that can considerably amplify the Raman signals of surrounding analyte molecules. By carefully controlling their size, shape, and interparticle spacing, AuNPs may be made to exhibit LSPR, making them ideal candidates for boosting SERS signals.…”

Morphological Effects of Au Nanoparticles on Electrochemical Sensing Platforms for Nitrite Detection

“…Gold nanoflowers (AuNFs) have attracted more attention because of the large specific surface area and the resultant high catalytic or SERS activities [ 25 , 26 ]. Researchers used to synthesize the AuNFs by seed-mediated growth and template protection [ 27 , 28 ].…”