title: Cost-Effective Plasmonic Platforms: Glass Capillaries Decorated with Ag@SiO2Nanoparticles on Inner Walls as SERS Substrates.
abstract: A cost-effective method for the fabrication of a glass capillary based plasmonic platform for the selective detection and identification of analytes of importance in health, environment, and safety is demonstrated. This was achieved by coating Ag@SiO2nanoparticles (Ag ∼ 60 nm) having silica shell of varying thickness (∼2 and ∼25 nm) on the inside walls of glass capillaries, over 2 cm in length, with uniform coverage. It was found that the particle density on the surface plays a decisive role on the enhancement of Raman signals. Multiple hot spots, which are essentially junctions of amplified electric field, were generated when ∼30 Ag@SiO2particles/μm2were bound onto the walls of glass capillaries. The pores of the silica shell allow the localization of analyte molecules to the vicinity of hot spots resulting in signal enhancements of the order of 1010(using pyrene as analyte; excitation wavelength, 632.8 nm). The applicability of Ag@SiO2coated capillaries for the detection of a wide range of molecules has been explored, by taking representative examples of polyaromatic hydrocarbons (pyrene), amino acids (tryptophan), proteins (bovine serum albumin), and explosives (trinitrotoluene). By increasing the thickness of the silica shell of Ag@SiO2nanoparticles, an effective filtration cum detection method has been developed for the selective identification of small molecules such as amino acids, without the interference of large proteins.
authors.affiliation: School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , CET Campus, Thiruvananthapuram 695 016, India.|Photosciences and Photonics, CSIR-National Institute for Interdisciplinary Science and Technology , Thiruvananthapuram 695 019, India.
authors.forename: M
authors.initials: M
authors.lastname: Shanthil
authors.affiliation: School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , CET Campus, Thiruvananthapuram 695 016, India.
authors.forename: Hemna
authors.initials: H
authors.lastname: Fathima
authors.affiliation: School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , CET Campus, Thiruvananthapuram 695 016, India.
authors.forename: K
authors.identifier: http://orcid.org/0000-0003-1279-308X
authors.initials: K
authors.lastname: George Thomas
keywords: Ag nanoparticle; SERS; capillary tube; hot spot; plasmonic platform; silica shell