Hydrophobic Teflon films as concentrators for single-molecule SERS detection

Lu, Liqiang; Yin, Zheng; Qu, Wen-Gang; Yu, Han‐Qing; Xu, An‐Wu

doi:10.1039/c2jm33955b

Cited by 77 publications

(52 citation statements)

References 37 publications

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“…Further dilution of analyte concentrations to eventually 0.1 fmol gives a relatively constant SERS intensity of ∼10 counts, which we attribute to the submonolayer Langmuir adsorption of Sudan I on our SERS platform (SI, Figure S10). 19,35 Thus, the detection limit of Sudan I is determined as 0.1 fmol (SI, Figure S11), and we again exclude any potential background interferences from our SHP-OP SERS platform (control in SI, Figure S11A). Consequently, an analytical enhancement factor of (1.87 × 10 8 ) is determined (SI, Figure S11), which is ∼10 3 -fold less compared to the analytical enhancement factor calculated using water-soluble melamine due to the difference in analyte concentration factor for both liquids, and also the Raman cross sections of the respective analytes.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Superhydrophobic-Oleophobic Ag Nanowire Platform: An Analyte-Concentrating and Quantitative Aqueous and Organic Toxin Surface-Enhanced Raman Scattering Sensor

Lee

Phang

et al. 2014

Anal. Chem.

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The ultratrace detection and quantification of toxins in both water and organic liquids remains a challenge due to the random spreading and dilution of liquids on substrate-based sensors, especially for organic liquids with low surface tension. Herein, we fabricate a superhydrophobic-oleophobic (SHP-OP) 3D Ag nanowire mesh-like surface-enhanced Raman scattering (SERS) platform to overcome the random spreading issue, demonstrating ultratrace toxin sensing in both water and organic liquid. Our SHP-OP SERS platform is able to concentrate analyte solutions in water and toluene to 100-fold and 8-fold smaller areas, respectively, as compared to its omniphilic counterparts. The synergy of analyte-concentrating ability and intense SERS-enhancing properties on our SHP-OP SERS platform enables quantitative and ultratrace detection of melamine and Sudan I down to 0.1 fmol in water and toluene, respectively, using just 1 μL of analyte solution. These detection limits are 10(3)-fold lower than the regulatory limits, clearly indicating our SHP-OP SERS platform as an appealing universal ultratrace toxin sensor. The ultratrace detection of spiked melamine in liquid milk down to 100 fmol also highlights the suitability of our SHP-OP SERS platform for the sensing of food toxins in real samples.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Superhydrophobic-Oleophobic Ag Nanowire Platform: An Analyte-Concentrating and Quantitative Aqueous and Organic Toxin Surface-Enhanced Raman Scattering Sensor

Lee

Phang

et al. 2014

Anal. Chem.

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“…For example, Xie et al described a method that allows reproducibly obtaining self‐assembled monolayers of Au nanorods by controlling humidity and temperature of the drying environment . Furthermore, it has been determined that wettability and temperature of the substrate on which the colloid drop is casted has great influence on how the NPs settle . All of these factors should be considered when preparing SERS substrates by drying the metal NPs colloids.…”

Section: Introductionmentioning

confidence: 99%

Uric acid detection by means of SERS spectroscopy on dried Ag colloidal drops

Pučetaitė

Velička

Pilipavičius

et al. 2016

J. Raman Spectrosc.

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Uric acid concentration in human bodily fluids is an important marker for disorders such as gout, pre‐eclamsia or cardiovascular disease. However, currently used methods for its detection either lack sensitivity or require sophisticated, bulky and expensive equipment. In this work, we show that by using surface‐enhanced Raman scattering spectroscopy (SERS) on dried Ag colloidal drops and with 1064 nm excitation, concentrations of uric acid in aqueous solutions down to 10−6 M can be detected. Such sensitivity is sufficient for medical applications as concentration of uric acid in various bodily fluids are in the range of 10−3–10−4 M. Drying of the colloidal drops is known to result in the formation of ‘coffee‐ring’ structures that allow obtaining high enhancements but poor reproducibility. Here, the formation of the structures was avoided by choosing aluminum oxide as a base substrate and by controlling environment conditions. Despite the fact that variations of signal enhancement from sample to sample prevent quantitative analysis from being performed, the results of this work imply that strict control of sample preparation conditions could lead to obtaining reproducible SERS enhancements. Results of density functional theory calculations of uric acid tautomer – five‐atom silver cluster complexes performed for the first time show that the differences between Raman and SERS spectra of uric acid can be mainly explained by tautomerization of the molecule and its bonding to the silver surface. Assignment of spectral bands is important for correct SERS signal interpretation and detection of uric acid in biological fluids in the future studies. Copyright © 2016 John Wiley & Sons, Ltd.

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“…3. 3d, 18 In comparison, the spectral curves achieved from the hydrophilic substrates showed significant deviation (Fig. The strongest peaks at wavenumbers of 1509 cm −1 , 1359 cm −1 and 611 cm −1 in Raman spectroscopy were selected to characterize the quantity of R6G molecules.…”

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confidence: 99%