Centrifuge tube-based SERS sensor on heterogenous dimers of plasmonic coupling as a microreactor for ultrasensitive SERS sensing pesticide residues in environmental water

Abstract

In situ fast detection of contaminants in solution is the most mature commercial SERS detection protocol and serves as an effective workflow solution for protecting the public from unexpected exposure to harmful pollutants. However, it is frequently hindered by weakly adsorbed species, trace content, and complicated organic compounds. Surface-enhanced Raman spectroscopy (SERS) nanoprobes, constructed through a simple and cost-effective fabrication method, are widely employed in sensing trace substances across various research fields. They excel in providing fingerprinting identification of individual molecules, making them a valuable tool for the detection and quantification of harmful components. Herein, we introduce a novel centrifuge tube-based SERS chip designed as an analytical tool for achieving field-deployable solution detection. This chip is created through a consecutive process involving the unique assembly of heterogeneous plasmonic materials. We achieve this by the co-coupling of Au nanospheres (NSs) and Ag nanocubes (NCs) to form AgNCs/AuNSs films based on a centrifugation process. This approach offers remarkable advantages, including simplicity of operation, straightforward integration, and mass production capabilities. Concurrently, the co-assembly of AgNCs and AuNSs efficiently generates plasmonic metasurfaces and reduces interparticle distance inside the centrifuge tube, ensuring ultrasensitive and reproducible SERS measurements. The optimized SERS sensor demonstrates ultrahigh sensitivity at trace concentrations of 10−10 M, a high enhancement factor (EF) of 4.69×108, and strong reproducibility with a relative standard deviation (RSD) of approximately 7.5% at 10−6 M. To assess its practical feasibility, experimental results show that the sensor can directly identify thiram pesticide residues at a low concentration of 10−8 M with an EF of 1.38 × 107. This proposed sensor not only offers a sensitive, portable, and cost-effective tube-based SERS platform but also has the potential to serve as a versatile SERS sensor for field-deployable identification in ultra-trace molecular detection in solution.