Bicontinuous microemulsion as confined reaction media for the synthesis of plasmonic silver self-assembled hierarchical superstructures

• Published in: Nanotechnology Vol. 31; no. 42; p. 425601
• Main Authors: Adesuji, Elijah T, Torres-Guerrero, Verónica O, Arizpe-Zapata, J Alejandro, Videa, Marcelo, Sánchez-Domínguez, Margarita, Fuentes, Keyla M
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 16.10.2020
• Subjects: bicontinuous microemulsion; hierarchical silver; plasmonic superstructures; SERS
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/ab9f75

Plasmonic superstructures may concentrate hot spots both on the external surface and within the inner gaps of the assembly. However, these materials are usually obtained by two-steps procedures from synthesis of plasmonic nanoparticles to their 3D assembly. The interconnected nano-network of water and oil channels in a bicontinuous microemulsion (BμE) may act as a preorganized reaction system giving reticulated materials. In this work, a silver hierarchical superstructure (HSS-AgCt) was obtained in the water channels of a BµE in a one-pot procedure. The characterization of the morphology and crystalline structure revealed that this superstructure is composed of silver nanoparticles embedded in polymeric silver citrate forming a 3D mesh of interconnected fibers with mean width of 30 nm. The aging of HSS-AgCt in the BμE allowed the degradation of the citrate fibers giving rise to interconnected spherical silver nanoparticles (HSS-Ag) of 8 nm as measured from TEM images. Rhodamine 6-G was detected by SERS up to 10-12 M with an analytical enhancement factor of 109 for both materials using a 633 nm laser operating at 0.85 mW (5% of the nominal power). These results introduce a novel route to obtain highly sensitive SERS substrates in one-pot procedures by using BμE as a nanoreactor and template.