Synthesis of AuAg@Ag core@shell hollow cubic nanostructures as SERS substrates for attomolar chemical sensing

Multilayer Gold-Silver Bimetallic Nanostructures to Enhance SERS Detection of Drugs

“…Bimetallic silver and gold nanorods were prepared by synthesizing gold nanorods (AuNRs) through a chemical reduction method and then by growing consecutive silver (Au@AgNRs) and gold (Au@Ag@AuNRs) coating layers around the core structure. The combination of different metals in the same nanostructure allows to improve the properties of the single metals and originates a hybrid material with new enhanced characteristics, such as tunable plasmonic resonance and improved SERS efficiency [5,25]. Since gold allows an excellent size/shape control and provides high stability, this metal is an optimal candidate for the core structure and the final coating layer.…”

“…Surface-enhanced Raman scattering (SERS) is a non-destructive and ultra-sensitive analytical technique, which allows rapid molecular-specific detection of a wide range of targets [1,2]. Since its discovery in 1974, SERS has been applied for the analytical sensing of many molecules of biological interest ranging from small organic molecules [3][4][5], pesticides [6,7] and drugs [8,9] to larger structures such as proteins, nucleic acids and cells [10][11][12][13]. Due to its promptness, high sensitivity and molecular specificity, SERS is particularly useful for drug detection.…”

“…Traditionally, silver-based nanomaterials are used in SERS applications, since this metal demonstrated to induce strong enhancement effects [8,9]; however, it has been already reported that silver nanostructures can easily oxidase at room temperature conditions [3] and show a strong tendency to growth and/or reshape upon prolonged irradiation [21,22]. For this reason, in recent years, the attention was focused on hybrid nanomaterials, in which the properties of two or more elements are combined in a single platform [5,7,[23][24][25][26]. Hybrid materials proved to be much more effective than the separated components, showing emerging properties with respect to the sum of the properties derived from the starting elements [5,25].…”

“…For this reason, in recent years, the attention was focused on hybrid nanomaterials, in which the properties of two or more elements are combined in a single platform [5,7,[23][24][25][26]. Hybrid materials proved to be much more effective than the separated components, showing emerging properties with respect to the sum of the properties derived from the starting elements [5,25]. Thus, SERS effect has been improved by combining different metals in alloys or core-shell structures [23,25,27] or by blending metals with metal oxides or polymers [24,26], in order to obtain multi-use nanoplatforms in which plasmonic effects are enhanced [4,23,24].…”

“…Gold and silver can be combined in hybrid bimetallic structures and the formation of core-shell structures composed by these two metals already proved to be a good strategy to improve SERS efficiency [5,25,27]. In this work, we have prepared bimetallic core-shell colloidal nanorods to be used as SERS platforms; while gold provides excellent morphological control and stability for the structure, the combination with silver strongly increases SERS efficiency.…”