Dragonfly wing decorated by gold nanoislands as flexible and stable substrates for surface-enhanced Raman scattering...

A flexible and stable biomimetic SERS substrate was successfully fabricated by depositing gold (Au) nanoislands on the dragonfly wings (DW) via a simple DC magnetron sputtering system. Characterizations of the Au/DW nanostructure indicated that the optimum Au/DW-45 (sputtering time was 45 min) substrate owns high sensitivity, good stability and outstanding reproducibility. The limit of detection (LOD) for Rhodamine 6 G (R6G) was as low as 10^-7 M and enhancement factor (EF) was calculated to be 2.8 × 10⁶. 70-day-duration stability tests showed that Raman intensity of R6G reduced only by 12.9% after aging for 70 days. The maximum relative standard deviations (RSD) of SERS intensities from 100 positions of Au/DW-45 substrate were less than 8.3%, revealing outstanding uniformity and reproducibility. Moreover, the flexible Au/DW-45 bioscaffold arrays were employed to solve the vital problem of pesticide residues. By directly sampling from tomato peels via a "press and peel off" approach, cypermethrin has been rapidly and reliably determined with a LOD centered at 10^-3 ng/cm² and a correlation coefficient (R²) of 0.987. The positive results demonstrated that the Au-based DW biomimetic arrays may offer an efficient SERS platform for the identification of various pesticide residues on real samples.