Flexible, high-performance and facile PVA/cellulose/Ag SERS chips for in-situ and rapid detection of thiram pesticide in apple juice

Flexible surface-enhanced Raman scattering (SERS) sensors have gained significant attention for their practical applications in detecting chemical and biological molecules. However, the fabrication of flexible SERS chips is often complex and requires advanced techniques. In this study, we present a simple and rapid method to design a flexible SERS chip based on polyvinyl alcohol (PVA), cellulose, and silver nanoparticles (AgNPs) using mechanical stirring and drying methods. Benefiting from the abundant hydroxide groups on cellulose, AgNPs easily adhere and distribute evenly on the cellulose surface. The combination of PVA and cellulose forms a bendable film-like SERS chip. This chip allows convenient immersion in liquid analyte samples. We demonstrate its effectiveness by using it to detect the thiram pesticide in apple juice using the "dip and dry" method, achieving an outstanding detection limit of 1.01 x 10-8 M. The Raman signals on the SERS chips exhibit high repeatability and reproducibility, with relative standard deviation values below 10%. These findings show that the flexible PVA/cellulose/Ag SERS chips is a strong candidate for real-world analysis.