Fabrication of plasmonic absorbent cotton as a SERS substrate for adsorption and detection of harmful ingredients in food

We report on a simple method for fabricating plasmonic absorbent cotton fibers conformally dyeing with Ag NPs to be used as surface-enhanced Raman scattering (SERS) substrates. The Ag NPs were integrated on the surface of cotton by a process in which Ag-NP seeds were immobilized on cotton via electroless deposition. Scanning electron microscope, transmission electron microscopy imaging as well as elemental mapping analysis provided evidence that the Ag NPs were densely immobilized on the surface of cotton. By controlling the amount of AgNO3 in growth media, the optimal SERS absorbent cotton-Ag was obtained by using 20 mM of AgNO3. The high absorbency of cotton could enrich the analyte concentration within 3 min, which brings additional enhancement sensitivity in SERS sensing. In addition, the mechanical flexibility of plasmonic cotton-Ag SERS substrate makes it suitable for swiping the SERS substrate on the surface of apple, the limit of detection of thiram from apple was lower than 0.1 ppm. Finally, the multiplex sensing capability of the plasmonic cotton was demonstrated by identifying pesticides from their mixture.

Automated summary

A simple method for fabricating plasmonic absorbent cotton fibers dyeing with Ag NPs was reported. The Ag NPs were densely immobilized on the cotton surface, providing additional enhancement sensitivity in SERS sensing. The plasmonic cotton-Ag SERS substrate showed multiplex sensing capability for identifying pesticides from their mixture.