Transparent and flexible AuNSs/PDMS-based SERS substrates for in-situ detection of pesticide residues

Herein, we developed a PDMS-based flexible SERS substrate modified with gold nanostars (AuNSs) for insitu detection of pesticide residues on fruit surfaces. AuNSs with sharp branches were assembled on aminated PDMS membrane by chemical bonding effect. The AuNSs/PDMS substrate showed good signal uniformity, stability and sensitivity using the Raman signal molecule 4-MBA and the detection concentration of 4-MBA was as low as 10(-8) mol/L. Then the AuNSs/PDMS substrate was used to detect methyl parathion (MP) standard solution. A good linear relationship between SERS intensity at 1342 cm(-1) and MP concentration was established in the range of 4 mu g/mL-100 mu g/mL, and the limit of detection was down to 1.946 mu g/mL. Moreover, the AuNSs/PDMS substrate was directly covered on the surface of MP contaminated apple, and the Raman laser was incident from the back of substrate to achieve in-situ detection of pesticide residues. The recovery ratio indicated that the fabricated SERS substrate was realized successfully in real sample detection. AuNSs/PDMS substrate eliminates the requirement for sample preprocessing steps before testing, which can be used as a method for rapid inspection of pesticide in agricultural products on site. (C) 2021 Elsevier B.V. All rights reserved.