Marangoni flow-guided molecular accumulation for sensitive and rapid SERS detection of phthalates

[Display omitted] •Sub-ppb sensitivity and reliability were achieved for plasticizer detection.•Five major plasticizers were discriminated by using a principal component analysis.•Delocalization of carboxylic groups was discussed on the basis of spectral shifts.•This strategy is highly suitable for the early screening of toxic substances. Public attention has been emerging for the prevention and assessment of healthcare risks from phthalate esters (PAEs) in daily life. For the effective detection of small environmentally hazardous materials, we suggest two major points: i) the formation of high-density hotspots and ii) the delivery of molecules to the activated plasmonic regions. In this study, we developed a method for laser-induced Marangoni flow in cotton fabric (CF) nanopillars (NPs) deposited with Au (Au/CFNPs) for the detection of PAEs by surface-enhanced Raman spectroscopy (SERS). We optimized the performance of the Au/CFNP platforms by adjusting both the maskless plasma etching time and the Au deposition thickness. Narrow (∼8 nm) and populated hotspots were achieved at an Ar plasma treatment time of 30 s and a Au thickness of 150 nm. The molecular behaviors were observed via real-time monitoring of SERS signals. Under continuous laser illumination, Marangoni radial convection flow became predominant over the outward capillary force, resulting in molecular accumulation in the detection areas. For small probe dyes and PAEs, the maximum intensities were achieved within 80 s after the injection of analytes and their signal fluctuations were estimated to have a relative standard deviation of