title: A highly tunable and fully biocompatible silk nanoplasmonic optical sensor.
abstract: Novel concepts for manipulating plasmonic resonances and the biocompatibility of plasmonic devices offer great potential in versatile applications involving real-time and in vivo monitoring of analytes with high sensitivity in biomedical and biological research. Here we report a biocompatible and highly tunable plasmonic bio/chemical sensor consisting of a natural silk protein and a gold nanostructure. Our silk plasmonic absorber sensor (SPAS) takes advantage of the strong local field enhancement in the metal-insulator-metal resonator in which silk protein is used as an insulating spacer and substrate. The silk insulating spacer has hydrogel properties and therefore exhibits a controllable swelling when exposed to water-alcohol mixtures. We experimentally and numerically show that drastic spectral shifts in reflectance minima arise from the changing physical volume and refractive index of the silk spacer during swelling. Furthermore, we apply this SPAS device as a glucose sensor with a very high sensitivity of 1200 nm/RIU (refractive index units) and high relative intensity change.
authors.affiliation: †Department of Physics and Astronomy and Inter-University Semiconductor Research Center and ‡Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea.|§Department of Physics and ∥Department of Energy Systems Research, Ajou University, Suwon 443-749, Republic of Korea.
authors.forename: Myungjae
authors.initials: M
authors.lastname: Lee
authors.affiliation: †Department of Physics and Astronomy and Inter-University Semiconductor Research Center and ‡Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea.|§Department of Physics and ∥Department of Energy Systems Research, Ajou University, Suwon 443-749, Republic of Korea.
authors.forename: Heonsu
authors.initials: H
authors.lastname: Jeon
authors.affiliation: †Department of Physics and Astronomy and Inter-University Semiconductor Research Center and ‡Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea.|§Department of Physics and ∥Department of Energy Systems Research, Ajou University, Suwon 443-749, Republic of Korea.
authors.forename: Sunghwan
authors.initials: S
authors.lastname: Kim
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry; D008670:Metals / Q000737:chemistry* / Q000302:isolation & purification; D047011:Silk / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D001672:Biocompatible Materials; D008670:Metals; D047011:Silk; D006046:Gold
keywords: Silk fibroin hydrogel; biocompatible device; metal−insulator−metal resonators; plasmonic sensor; surface plasmon