title: Fabrication of SERS swab for direct detection of trace explosives in fingerprints.
abstract: Swab sampling is of great importance in surface contamination analysis. A cotton swab (cotton Q-tip) was successfully transformed into surface-enhanced Raman scattering (SERS) substrate (SERS Q-tip) through a bottom-up strategy, where Ag NPs were first self-assembled onto the Q-tip followed by in situ growing. The capability for direct swab detection of Raman probe Nile Blue A (NBA) and a primary explosive marker 2,4-dinitrotoluene (2,4-DNT) using the SERS Q-tip was explored. It was found that at optimum conditions, a femotogram of NBA on glass surface could be swab-detected. The lowest detectable amount for 2,4-DNT is only ∼1.2 ng/cm(2) (total amount of 5 ng) on glass surface, 2 orders of magnitude more sensitive than similar surface analysis achieved with infrared technique, and comparable even with that obtained by ion mobility spectrometry-mass spectrometry. Finally, 2,4-DNT left on fingerprints was also analyzed. It was found that SERS signal of 2,4-DNT from 27th fingerprint after touching 2,4-DNT powder can still be clearly identified by swabbing with the SERS Q-tip. We believe this is the first direct SERS swabbing test of explosives on fingerprint on glass. Considering its relative long shelf life (>30 d), the SERS Q-tip may find great potential in future homeland security applications when combined with portable Raman spectrometers.
authors.affiliation: Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University , Chengdu, 610031, China.
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Gong
authors.forename: Hongjie
authors.initials: H
authors.lastname: Du
authors.forename: Fansheng
authors.initials: F
authors.lastname: Cheng
authors.forename: Cong
authors.initials: C
authors.lastname: Wang
authors.forename: Canchen
authors.initials: C
authors.lastname: Wang
authors.forename: Meikun
authors.initials: M
authors.lastname: Fan
mesh_terms: D003878:Dermatoglyphics; D004136:Dinitrobenzenes / Q000032:analysis*; D053834:Explosive Agents / Q000032:analysis*; D005385:Fingers; D006801:Humans; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D013059:Spectrum Analysis, Raman
chemical_list: D004136:Dinitrobenzenes; D053834:Explosive Agents; C016403:2,4-dinitrotoluene