title: Surface-Enhanced Raman Spectroscopy on Liquid Interfacial Nanoparticle Arrays for Multiplex Detecting Drugs in Urine.
abstract: The design and application of liquid interfacial plasmonic platform is still in its infancy but is an exciting topic in tunable optical devices, sensors, and catalysis. Here, we developed an interfacial surface-enhanced Raman scattering (SERS) platform through the large-scale self-assembly of gold nanoparticle (GNP) arrays at the cyclohexane (CYH)/water interface for detecting trace drug molecules in the urine of humans. The molecules extracted by the CYH phase from a urine sample were directly localized into the self-organized plasmonic hotspots, yielded excellent Raman enhancement, and realized the substrate-free interfacial SERS detection. Synchrotron radiation small-angle X-ray scattering (SR-SAXS) experiments reveals a good uniformity of approximately 2-3 nm interparticle distance in the GNP arrays. SERS colocalization experiments demonstrated that amphetamine molecules of different concentration levels could be loaded into the interfacial GNP arrays and realized the coassembly together with nanoparticles at the liquid/liquid interface. Interfacial GNP arrays with dynamic nanogaps in liquid interfacial structure can make surrounding molecules easily diffuse into the nanogaps. In contrast, the fixed GNP arrays on Si wafer were more irregular, such as multilayer stack, random aggregates, and voids, during the drying process. When the drugs directly participate in the self-assembly process, it becomes easier for analytes diffusing into the nanogaps of GNP arrays, produces a concentration effect, and amplified the SERS sensitivity. This feature also enables molecules to be adsorbed evenly in the arrays and makes a more uniform distribution of both the analytes and GNPs in the liquid interface and realizes the significant increase in signal reproducibility. Interfacial SERS produced a standard deviation of 12.5% at 1001 cm(-1) peak of methamphetamine (MAMP) molecules under the concentration of 1 ppm, implying a good reproducibility. Moreover, dual-analyte detection at organic and aqueous phases was also realized and confirmed a good capability for analytes detection by liquid interfacial SERS platform, which promises nonengineering detection of analytes dissolved in often-inaccessible environments.
authors.affiliation: Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.|Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing 400714, China.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.|Molecular Sciences and Biomedicine Laboratory, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering and College of Biology, Collaborative Innovation Center for Molecular Engineering and Theranostics, Hunan University , Changsha 410082, China.
authors.forename: Honglin
authors.initials: H
authors.lastname: Liu
authors.affiliation: Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.|Department of Chemistry, University of Science and Technology of China , Hefei 230026, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Mao
authors.affiliation: Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Meng
authors.affiliation: Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.
authors.forename: Liangbao
authors.initials: L
authors.lastname: Yang
authors.affiliation: Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.
authors.forename: Jinhuai
authors.initials: J
authors.lastname: Liu
mesh_terms: D003510:Cyclohexanes / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D008694:Methamphetamine / Q000652:urine*; D046228:Microarray Analysis; D015203:Reproducibility of Results; D053838:Scattering, Small Angle; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D003510:Cyclohexanes; D014867:Water; D008694:Methamphetamine; C506365:Cyclohexane; D006046:Gold