Inhibition-type SERS strategy based on silver nanowires@ZrO2 composite substrate: Achieving high-sensitivity and specific detection of methyl parathion

Surface-enhanced Raman scattering (SERS) technology is limited in the direct detection of molecules with weak Raman scattering such as methyl parathion (MP). Development of an indirect detection strategy for weakly Raman active substances is essential. Herein, a novel SERS detection method was developed for the inhibition-type indirect detection of MP with ZrO 2 -coated silver nanowires (AgNWs@ZrO 2 ) as substrate. The mechanism relies on specific MP adsorption through Zr 4+ Lewis acid sites and P/S-ZrO 2 interactions, which spatially and electronically suppresses 4-MBA probe signals, and then the quantitative relationship between the measured object and the decline value of Raman intensity can be established. With the gradual increase of MP concentration in the range of 0.5 ng/mL ∼ 1 μg/mL, the SERS intensity of 4-MBA decreased accordingly, showing a good linear relationship (R 2  = 0.996), and the analytical enhancement factor (AEF) reached 1.6 × 10 6 , overcoming traditional SERS limitations for the molecules with weak Raman scattering. The ZrO 2 layer maintains electromagnetic coupling while preventing oxidation, thereby enhancing the reproducibility, uniformity and stability of the substrate during the analysis process. The prepared AgNWs@ZrO 2 was successfully applied for trace detection of MP residues in pear peel and apple juice. This study is expected to provide a simple and feasible method for trace detection of the molecules with weak SERS activity.