Silver-Coated Dye-Embedded Silica Beads: A Core Material of Dual Tagging Sensors Based on Fluorescence and Raman Scattering

• Published in: ACS applied materials & interfaces Vol. 3; no. 2; pp. 324 - 330
• Main Authors: Kim, Kwan, Lee, Hyang Bong, Choi, Jeong-Yong, Shin, Kuan Soo
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 23.02.2011
• Subjects: Animals; Antibodies - chemistry; Antibodies - metabolism; Antigen-Antibody Reactions; Humans; Immunoassay - methods; Mice; Microscopy, Electron, Scanning; Molecular Probe Techniques; Nanostructures - chemistry; Rhodamines - chemistry; Silicon Dioxide - chemistry; Silver - chemistry; Spectrometry, Fluorescence - methods; Spectrum Analysis, Raman - methods; silica bead; silver nanostructure; antigen−antibody binding; surface-enhanced Raman scattering; fluorescence; rhodamine B isothiocyanate
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am1009474

We have developed a new type of dual-tag sensor for immunoassays, operating via both fluorescence and surface-enhanced Raman scattering (SERS). A one-shot fluorescence image over the whole specimen allows us to save considerable time because any unnecessary time-consuming SERS measurements can be avoided from the signature of the fluorescence. Dye-embedded silica beads are prepared initially, and then SERS-active silver is coated onto them via a very simple electroless-plating method. The Raman markers are subsequently assembled onto the Ag-coated silica beads, after which they are stabilized by silanization via a biomimetic process in which a poly(allylamine hydrochloride) layer formed on the Raman markers by a layer-by-layer deposition method acting as a scaffold for guiding silicification. In the final stage, specific antibodies are attached to the silica surface in order to detect target antigens. The fluorescence signal of the embedded dye can be used as a fast readout system of molecular recognition, whereas the SERS signals are subsequently used as the signature of specific molecular interactions. In this way, the antibody-grafted particles were found to recognize antigens down to 1 × 10−10 g mL−1 solely by the SERS peaks of the Raman markers.