Multiscale Photonic Crystal Enhanced Core–Shell Plasmonic Nanomaterial for Rapid Vapor-Phase Detection of Explosives

Abstract

Surface-enhanced Raman scattering (SERS) has started to attract attention in vapor sensing; however, practical applications require shorter response time and better sensitivity. Herein, we report a facile multiscale SERS substrate for trace-level detection of vapors using a portable Raman spectrometer through the synergistic integration of biologically fabricated diatom photonic crystals and gold−silica core−shell nanoparticles. The multiscale substrate is composed of (1) a micrometer-scaled, 3dimensional, diatom biosilica frustule enabling efficient vapor− substrate interaction for rapid sensing, (2) periodic pores, on the order of 100 nm, inducing plasmonic-photonic coupled resonances for enhanced SERS signals, (3) gold nanoparticle cores, with a diameter on the order of 10 nm, contributing plasmonic field enhancements, and (4) porous 1 nm thick silica core−shells enabling analyte vapor adsorption and concentration. The combination of the hierarchal, multiscale features results in a SERS substrate capable of rapid and sensitive detection of target vapors in air. The multiscale substrate's functionality is characterized using the polycyclic aromatic hydrocarbon pyrene, and the contribution from each scale is verified by using a stagnant vapor chamber. The sensor equilibrates in only 3 min, and detection is achieved down to 1 ppm. The sensor is then applied to the detection of explosive 2,4-dinitrotoluene vapor below 100 ppb in an airflow chamber to replicate practical detection conditions, achieving detection in under 3 min at room temperature and under 1 min when heated. This work successfully demonstrates detection of explosive vapor and represents a significant advancement toward widespread vapor sensing via SERS.

Applications of surface‐enhanced Raman spectroscopy based on portable Raman spectrometers: A review of recent developments

“…The detection time was as low as 3 min and the detection sensitivity could be as low as 1 ppm (Figure 1d). [88] In addition to the earlier environmental pollutants, portable Raman spectrometers can also be used for rapid analysis of chemical warfare agents (CWAs) and pathogens in the environment. It remains a challenge for on-site SERS applications to detect gaseous chemicals with small cross-sections.…”

“…The detection time was as low as 3 min and the detection sensitivity could be as low as 1 ppm (Figure 1d). [ 88 ]…”

Enzyme-Assisted Metabolically Coated Bimetallic Thalassiosira pseudonana Nanosilica as a Surface-Enhanced Raman Scattering Substrate for Specific Screening of Prostate Cancer Individuals

“…Diatoms, single-cell algae, fabricate a nanoporous silica shell (frustules), representing an example of a biologically derived biomaterial Thalassiosira pseudonana, as the model diatom, produces frustules with hierarchical channels that resemble two-dimensional (2D) photonic crystals possessing photonic properties. , The in vivo incorporation of optically active materials onto nanosilica diatom frustules (DF) significantly imparts the optoelectronic properties of frustules. , Similarly, integrating photonic crystal structure (nanosilica) with plasmonic nanoparticles (NPs) holds significant promise for surface-enhanced Raman scattering (SERS) sensitivity. ,, Notably, the localized surface plasmon resonance (LSPR) by laser excitation remarkably enhances the Raman scattering of molecules when the diatomite nanosilica is coated with noble metal nanoparticles. , The pores array on the DF enhances LSPR via guided-mode resonance (GMRs) at visible wavelengths, thereby significantly increasing the SERS signals at plasmonic hotspots . For enhanced catalytic activity, the SERS substrate requires a high surface-to-volume ratio to generate abundant hotspots and the proximity of the analyte to the metallic core .…”

Fabrication, characterization and optical properties of Au-decorated Bi2Se3 nanoplatelets

“…Such a heterostructure can perform the functions of the different materials, including the absorption of light, charge transfer, quantum yielding, and enhancement of the near-field electromagnetic field. Therefore, the potential applications of heterostructures include (1) reduction of the signal-to-noise ratio of analytes 2 , (2) increasing the stability of colloidal particles 3 , (3) increasing the Raman intensity of analytes 4 , (4) detecting biomaterials 5 , (5) transporting drugs 6 , (6) use in high-efficiency photonic crystals 7 , and (7) high-efficiency photocatalysis 8 .…”