Bioavailability and translocation of platinum nanoparticles and platinum ions in rice (Oryza sativa L.): Nanoparticles biosynthesis and size- dependent transformation

Metal nanoparticles accumulation and bioavailability in plants raised much attention, specifically transformation and transportation of nanoparticles and their corresponding ions in plants are still unknown. In this work, rice seedlings were exposed to platinum nanoparticles (PtNPs) (with three sizes of 25, 50, and 70 nm) and Pt ions (with doses of 1, 2, and 5 mg/L) to investigate the influences of particle size and Pt form on bioavailability and translocation mech-anism of metal nanoparticles. Results based on single particle ICP-MS (SP-ICP-MS) demonstrated the biosynthesis of PtNPs in Pt ions treated rice seedlings. The particle size ranges at 75-79.3 nm were detected in Pt ions exposed rice roots, and further migrated up to rice shoots at 21.7-44.3 nm. After exposed to PtNP-25, the particles could transfer to shoots with the original size distribution detected in roots, even with the PtNPs dose change. PtNP-50 and PtNP-70 translocated to shoots with the particle size increase. For the rice exposure with three dose levels, PtNP-70 had the highest number-based bioconcentration factors (NBCFs) in all Pt species, while Pt ions had the highest bioconcentration factors (BCFs), a range of 1.43-2.04. All PtNPs and Pt ions could be accumulated in rice plants and further transferred to shoots, and particle biosynthesis was proved through SP-ICP-MS. The finding could help us better understand the influence of particle size and form on the transformations of PtNPs in environment.

Automated summary

Metal nanoparticles accumulation and bioavailability in plants, specifically the transformation and transportation of platinum nanoparticles and their ions in rice seedlings, were investigated in this study. Results showed that platinum ions can be biosynthesized into platinum nanoparticles in rice seedlings, and the particle size ranged from 75-79.3 nm in roots and 21.7-44.3 nm in shoots. Platinum nanoparticles could transfer to shoots while maintaining their original size distribution in roots, even with changes in dosage. Among all platinum species, PtNP-70 had the highest number-based bioconcentration factors (NBCFs), while Pt ions had the highest bioconcentration factors (BCFs). The findings provide insights into the influence of particle size and form on the transformations of platinum nanoparticles in the environment.