Surface-enhanced
Raman scattering (SERS) substrates capable of
working under laser excitation in a broad wavelength range are highly
desirable in diverse application fields. Here, we demonstrate that
the bioinspired Ag brochosomes, hollow microscale particles with submicroscale
pits, have broadband and omnidirectional SERS performance. The SERS
performance of the Ag brochosomes under near-infrared laser excitation
makes them promising for applications in biosensing fields, such as
the sensitive detection of Staphylococcus aureus bacteria and bovine hemoglobin protein. Additionally, the SERS intensity
was insensitive to the incident angle of the laser beam, resulting
from the spherical structure of the Ag brochosomes. The omnidirectional
SERS performance makes the Ag brochosomes have application potential
for in-the-field analysis using a hand-held Raman spectrometer for
which it is difficult to accurately control the laser beam normal
to the SERS substrates. Overall, the broadband and omnidirectional
brochosome SERS substrates will find applications in diverse fields,
particularly in biomedicine and in-the-field analysis.
Surface-enhanced Raman scattering (SERS) substrates were prepared by depositing Ag atoms on liquid surfaces via thermal evaporation at room temperature. These free-sustained substrates result in the formation of uniform Ag films, in which ramified Ag aggregates consist of substantial Ag nanoclusters with narrow gaps of several nanometers in between. SERS spectra of rhodamine 6G were investigated for this substrate to evaluate the SERS performance of this characteristic film morphology, and the results indicated that the SERS intensity from the closely-packed Ag nanostructures and small intervals were significantly enhanced. The dependence of SERS enhancement on the film thickness, nanoparticle size, and gap width was studied. An analytical model was proposed to simulate the electric field distribution during SERS detection, and the results validated the experimental observations.
We present an effective surface-enhancement Raman scattering (SERS) substrate enabled by depositing metallic film on a liquid surface at room temperature. Thermal evaporation is used to deposit Au atoms on silicone oil surface and then form quasi-continuous films. Due to the isotropic characteristics of the liquid surface, this film consists of substantial nanoparticles with uniform diameter, which is different from films fabricated on solid substrates and can be served as an applicable substrate for SERS detection. With the assistance of this substrate, SERS signals of rhodamine 6G were significantly enhanced, the dependence between SERS spectra and film thickness was investigated. Analytical simulation results confirm the experimental observations and the superiorities of our proposed method for preparation of SERS substrate. This work provides a potential application of metallic film deposition on free-sustained surface and holds promise as an efficient sensor in rapid trace detection of small molecule analytes.
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