1：Experimental Design and Method Selection:

The study involved in situ synthesis of gold nanoparticles (AuNPs) on pseudo-paper films (PPFs) using an iterative seeding method to create SERS-active substrates. The rationale was to achieve uniform nanoparticle distribution and high SERS activity. Theoretical models included surface-enhanced Raman scattering principles.

2：Sample Selection and Data Sources:

Samples included microcrystalline cellulose (MCC), pesticides (thiram, parathion methyl, malachite green), and chemicals for synthesis. Data were acquired through SERS measurements on prepared substrates.

3：List of Experimental Equipment and Materials:

Equipment included transmission electron microscope (Hitachi H-7650), scanning electron microscope (Tescan MIRA 3 XMU), X-ray diffractometer (D-MAX 2200 VPC), UV-Vis spectrophotometer (Shimadzu UV-3600), FT-IR spectrophotometer (Nicolet 6700), and portable Raman instrument (i-Raman Plus). Materials included various chemicals from suppliers like Sun Chemical Technology, Aladdin Company, and Sinopharm Chemical Reagent.

4：Experimental Procedures and Operational Workflow:

Procedures involved preparation of MCC-MA and MCC-MA-PEI copolymers, synthesis of SiO2 nanoparticles, fabrication of PPFs by casting and etching, in situ synthesis of AuNPs on PPFs using iterative seeding with HAuCl4 and reductants, and SERS detection by swabbing samples onto substrates followed by Raman measurement.

5：Data Analysis Methods:

Data were analyzed using SERS spectra intensity measurements, calculation of enhancement factors, and statistical analysis of reproducibility (relative standard deviation).