Cellulose nanofibers coated with silver nanoparticles as a SERS platform for detection of pesticides in apples

A nanocomposite based on cellulose nanofibers (CNFs) coated with silver nanoparticles (AgNPs) was developed in this study as a flexible and effective substrate for use in surface-enhanced Raman spectroscopy (SERS) analysis. An effective Raman indicator molecule, 4-aminothiophenol (pATP), was used to characterize AgNPs impregnated on CNFs. The CNF-AgNP films were used in SERS analysis to detect thiabendazole (TBZ) pesticides in apples. The influence of pH on the SERS spectra of TBZ was investigated because TBZ is a neutral molecule that has a low affinity for AgNPs. The pH of TBZ solution was decreased to below the TBZ's pK_a, thus enabling the electrostatic attraction between TBZ and AgNPs. CNFs can prevent the uncontrolled aggregation of AgNPs in low pH environment and serve as an effective AgNP/nanocellulose platform for SERS analysis. Results of this study demonstrate that CNF-AgNP nanocomposites can be used to rapidly detect TBZ pesticides in various food products.