Water/Oil Interfacial Self-Assembled Gold Nanoarrays Modified on Transparent Tape for In Situ Surface-Enhanced Raman Scattering

Herein, a novel in situ surface-enhanced Raman scattering (SERS) method was proposed based on the prepared SERS substrate with good flexibility, excellent optical transparency, and high SERS activity. The SERS substrate was fabricated through the Au colloids injected with an ethanol and hexane mixture to form Au monolayer film (Au MLF) on the water/oil interface and followed by transferred to the sticky side of transparent tape after hexane volatilization. Transmission electron microscopy and scanning electron microscopy revealed that Au NPs with particle sizes of 25 nm were densely assembled and evenly distributed on the flexible and transparent tape. This Au MLF/tape was directly covered on the irregular shape samples and the detection signal was collected by the laser transmitting into the tape and interacting with the analytes. The optimal SERS signal intensity was obtained by tuning the concentration of Au colloid and addition volume of the mixture of ethanol and hexane to regulate the numbers of Au NPs on water/oil interface. The SERS intensity of six sample points selected randomly show a good repeatability with RSD = 4.92% (n = 6 × 8) and satisfying uniformity with RSD of 8.6% within an area of 4.0 × 4.0 μm. Also, the obtained Au MLF/tape SERS substrate showed good detection accuracy and recovery when used to detect residual malachite green (MG) residue on the surfaces of real fish samples with detection limit of 0.04 μmol/L (S/N = 3). Therefore, the developed Au MLF/tape SERS substrate has potential applications in the in situ SERS detection.