Gold nanostars loaded fabrics as flexible, low-cost SERS substrates and swab-based detection of thiram on fruits and vegetables

Abstract

Currently, flexible surface-enhanced Raman spectroscopy (SERS) substrates have gained tremendous interest because they enable sample collection from uneven surfaces in real sensing applications. Herein, two different flexible textiles (cotton and synthetic fabrics) loaded with star-shaped gold (Au) nanoparticles (NPs) were utilized for detailed studies and are demonstrated as SERS substrates. Both fabrics were soaked in Au NPs synthesized via a simple wet chemical method. The colloidal star-shaped Au NPs were characterized by UV-visible absorption and transmission electron microscopy techniques. The C- and S-fabrics loaded with Au NPs were characterized by FESEM, x-ray diffraction, and x-ray photoelectron spectroscopic techniques. Subsequently, the SERS efficiency of C- and S-fabrics was examined with thiram, methylene Blue (MB), and Nile Blue (NB) molecules. Furthermore, pesticide (thiram) residues on the surfaces of a banana, an apple, and a spinach leaf were investigated by a simple swabbing method. The utility of these substrates is demonstrated by performing the SERS measurements using a portable Raman spectrometer, which is expedient for real-time applications.