title: Detecting explosive molecules from nanoliter solution: A new paradigm of SERS sensing on hydrophilic photonic crystal biosilica.
abstract: We demonstrate a photonic crystal biosilica surface-enhanced Raman scattering (SERS) substrate based on a diatom frustule with in-situ synthesized silver nanoparticles (Ag NPs) to detect explosive molecules from nanoliter (nL) solution. By integrating high density Ag NPs inside the nanopores of diatom biosilica, which is not achievable by traditional self-assembly techniques, we obtained ultra-high SERS sensitivity due to dual enhancement mechanisms. First, the hybrid plasmonic-photonic crystal biosilica with three dimensional morphologies was obtained by electroless-deposited Ag seeds at nanometer sized diatom frustule surface, which provides high density hot spots as well as strongly coupled optical resonances with the photonic crystal structure of diatom frustules. Second, we discovered that the evaporation-driven microscopic flow combined with the strong hydrophilic surface of diatom frustules is capable of concentrating the analyte molecules, which offers a simple yet effective mechanism to accelerate the mass transport into the SERS substrate. Using the inkjet printing technology, we are able to deliver multiple 100pico-liter (pL) volume droplets with pinpoint accuracy into a single diatom frustule with dimension around 30µm×7µm×5µm, which allows for label-free detection of explosive molecules such as trinitrotoluene (TNT) down to 10-10M in concentration and 2.7×10-15g in mass from 120nL solution. Our research illustrates a new paradigm of SERS sensing to detect trace level of chemical compounds from minimum volume of analyte using nature created photonic crystal biosilica materials.
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Xianming
authors.initials: X
authors.lastname: Kong
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Xi
authors.affiliation: School of Chemical, Biological & Environmental Engineering, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Le Duff
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Xinyuan
authors.initials: X
authors.lastname: Chong
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Erwen
authors.initials: E
authors.lastname: Li
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Fanghui
authors.initials: F
authors.lastname: Ren
authors.affiliation: School of Chemical, Biological & Environmental Engineering, Oregon State University, Corvallis, OR, 97331 USA.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Rorrer
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR, 97331 USA. Electronic address: wang@eecs.oregonstate.edu.
authors.forename: Alan X
authors.initials: AX
authors.lastname: Wang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D017377:Diatoms / Q000737:chemistry*; D053834:Explosive Agents / Q000032:analysis*; D057927:Hydrophobic and Hydrophilic Interactions; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D012822:Silicon Dioxide / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014303:Trinitrotoluene / Q000032:analysis*
chemical_list: D053834:Explosive Agents; D014303:Trinitrotoluene; D012834:Silver; D012822:Silicon Dioxide
keywords: Diatom biosilica; Hydrophilic surface; Inkjet printing; Photonic crystal; Surface-enhanced Raman scattering