Increase in the active ingredients of traditional Chinese medicine Isatis indigotica through iron nanoparticles supplementation versus carbon nanotubes: a comparative study

Abstract

The low yield and active ingredient content of medicinal plants is always a challenge. However, nanotechnology offers new tools for enhancing the biomass and metabolism of medicinal plants. In the present study, the effects of two nanomaterials (NMs) on the growth, photosynthesis, antioxidant system, mineral homeostasis, C/N accumulation, and content of active ingredients of Isatis indigotica (BLG) were investigated. BLG was grown in soil supplemented with 10–250 mg kg⁻¹ of multi-walled carbon nanotubes (CNTs) or iron oxide nanoparticles (Fe₂O₃ NPs) for 60 days in a greenhouse. The results showed that a low concentration (10 mg kg⁻¹) of Fe₂O₃ NPs promoted the growth of BLG, while the opposite trend was observed in the CNT treatment. Fe₂O₃ NPs at 10 mg kg⁻¹ effectively increased the shoot length and biomass by 21% and 14%, respectively. Notably, the Fe₂O₃ NPs could also effectively enhance the officinal ingredient content of BLG by regulating the antioxidant system, mineral element homeostasis, and carbon and nitrogen synthesis. Fe₂O₃ NPs at 10 mg kg⁻¹ increased the flavonoids, soluble sugars, and total protein content of BLG roots by 55%, 124%, and 59%, respectively. In conclusion, our results suggest that the Fe₂O₃ NPs can be used as a bio-fortifier to enhance the yield and officinal quality of BLG.