Protein-docking strategy boosting Raman detection sensitivity for aristolochic acid I

As one of the most potent carcinogens, aristolochic acid I (AAI) can be founded in many plants, which are widely used as raw materials in traditional Chinese medicine. Surface enhanced Raman scattering (SERS) method would be developed to detect the AAI in rapid way. However, hydrophobic AAI molecule with small scattering section hardly approaches onto the surface of metal nanoparticles, resulting in poor Raman detection sensitivity. In this work, bovine serum albumin (BSA) decorated silver nanoparticles (Ag NPs) with core-shell structure (Ag@BSA NPs) are successfully synthesized. The molecular docking induced strong interaction between BSA and AAI is validated by molecular simulation and Ag@BSA NPs could actively capture AAI and anchor the target molecule into the hot spots of Ag NPs, which greatly improves SERS response of AAI. The dynamic linear range for SERS detection of AAI is from 0.5 to 50 μM (R 2  = 0.9910) and the lowest detectable concentration of 0.28 μM is reached, which meeting the strict limitation of national standard regulation for AAI in cosmetic products. In addition, the method is applied for AAI determination in skin care products and good results are achieved.