title: Three-dimensionally assembled gold nanostructures for plasmonic biosensors.
abstract: Three-dimensional gold nanoarchitecture was fabricated by layer-by-layer (LbL) deposition of gold nanoparticles (AuNPs) and multiwalled carbon nanotubes (MWCNTs) on a glass substrate for a highly sensitive plasmonic biosensor using a conventional UV-vis instrument. Carboxyl-functionalized MWCNTs were reacted with 3-mercaptopropyltriethoxysilane (MPTES) to introduce multiple thiol groups onto MWCNTs. A self-assembled monolayer (SAM) of AuNPs on a glass chip was sequentially dipped into MPTES-functionalized MWCNTs (MWCNT-Si-SH) and AuNPs to form multilayers of AuNPs on MWCNTs. Such three-dimensionally assembled AuNPs provided a large surface area and multiple binding sites within a few steps of modification and microporous structures of multilayered MWCNTs to allow a high accessibility of target molecules. It was shown that the bulk refractive index (RI) sensitivity of these multilayered AuNPs (three-dimensional chip) appeared to be 5.6 times better than that of a monolayer of AuNPs on a glass chip (two-dimensional chip). The three-dimensional chips were further used for a biomolecular binding study, showing a detection limit as low as 0.5 nM for streptavidin and 3.33 nM for anti-human serum albumin (HSA), both of which were approximately 20 times higher than the sensitivity of the two-dimensional chips.
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457, Singapore.
authors.forename: Longhua
authors.initials: L
authors.lastname: Guo
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.forename: Dong-Hwan
authors.initials: DH
authors.lastname: Kim
mesh_terms: D000906:Antibodies / Q000276:immunology; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D012709:Serum Albumin / Q000032:analysis / Q000276:immunology; D019809:Streptavidin / Q000032:analysis / Q000378:metabolism; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods
chemical_list: D000906:Antibodies; D037742:Nanotubes, Carbon; D011506:Proteins; D012709:Serum Albumin; D006046:Gold; D019809:Streptavidin