In situ fabrication of 3D Ag@ZnO nanostructures for microfluidic surface-enhanced Raman scattering systems.
In this work, we develop an in situ method to grow highly controllable, sensitive, three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrates via an optothermal effect within microfluidic devices. Implementing this approach, we fabricate SERS substrates composed of Ag@ZnO structures at prescribed locations inside microfluidic channels, sites within which current fabrication of SERS structures has been arduous. Conveniently, properties of the 3D Ag@ZnO nanostructures such as length, packing density, and coverage can also be adjusted by tuning laser irradiation parameters. After exploring the fabrication of the 3D nanostructures, we demonstrate a SERS enhancement factor of up to ∼2×10(6) and investigate the optical properties of the 3D Ag@ZnO structures through finite-difference time-domain simulations. To illustrate the potential value of our technique, low concentrations of biomolecules in the liquid state are detected. Moreover, an integrated cell-trapping function of the 3D Ag@ZnO structures records the surface chemical fingerprint of a living cell. Overall, our optothermal-effect-based fabrication technique offers an effective combination of microfluidics with SERS, resolving problems associated with the fabrication of SERS substrates in microfluidic channels. With its advantages in functionality, simplicity, and sensitivity, the microfluidic-SERS platform presented should be valuable in many biological, biochemical, and biomedical applications.
Department of Engineering Science and Mechanics and ‡Department of Chemical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Yuliang
Y
Xie
Shikuan
S
Yang
Zhangming
Z
Mao
Peng
P
Li
Chenglong
C
Zhao
Zane
Z
Cohick
Po-Hsun
PH
Huang
Tony Jun
TJ
Huang
D004560:Electricity; D006367:HeLa Cells; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry*; D055620:Optical Phenomena; D012834:Silver / Q000737:chemistry*; D059010:Single-Cell Analysis; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties; D013696:Temperature; D015034:Zinc Oxide / Q000737:chemistry*
D012834:Silver; D015034:Zinc Oxide
Ag@ZnO nanostructures; microfluidics; optothermal effect; surface-enhanced Raman scattering (SERS)