The Application of Carotenoid-Coated Chitosan Nanoparticles to Reduce the PAHs Stress on Spinach Growth

Polycyclic aromatic hydrocarbons (PAHs) pose risks to human and animal health, and their accumulation in crops is a concern for the food chain in the environment. Nanoparticles (NPs) have shown potential for chemical delivery and can be used to enhance plant resistance to PAHs. In this study, carotenoid-coated chitosan nanoparticles (CCNPs) loaded with b-carotene were prepared and applied to spinach grown in PAH-contaminated soil. The size of the CCNPs varied based on reaction conditions with temperature, TPP, and pH, with sizes ranging from 260 to 682 nm. After four weeks of treatment, the spinach showed varying growth responses depending on the specific CCNP treatment. The treatment with CCNPs prepared at 20 degrees C, pH 6, and 10 mg/mL TPP resulted in the best spinach growth, while the treatment at 40 degrees C, pH 6, and a TPP concentration of 20 mg/mL hindered growth; and the growth ration increased by over 47.4% compared to the normal growing spinach, the final biomass reached 2.53 g per plant. In addition, phenanthrene (PHE) and pyrene (PYR) predominantly accumulated more in the spinach roots, with variations depending on the specific CCNP treatment. The exogenous application of CCNPs can reduce the PAH transfer to the shoots. The bioconcentration factors and transfer factors of PYR and PHE reduced differential movement within the spinach plants, and the spinach prefers PYR to PHE in biological accumulation. This study offers a new understanding of the mechanisms underlying NPs and PAHs interactions and NP's implications for crop protection and food safety.