Exploring single-particle ICP-MS as an important tool for the characterization and quantification of silver nanoparticles in a soybean cell culture

The application of nanomaterials in the plant biotechnology field is widespread for many functions, such as the enhancement of callus induction and sterilizer agents. On the other hand, the use of in vitro plant techniques has provided nanotoxicology information at a cellular level. In this context, the use of emerging analytical techniques, such as single-particle inductively coupled plasma mass spectrometry (spICP-MS), can contribute to the development of this field. This work aims to explore the use of spICP-MS to characterize and quantify silver nanoparticles (40, 60, and 80 nm) in a plant cell medium culture (Murashige and Skoog medium, or MS medium). A preliminary study was carried out to investigate the non-spectral interference caused by the matrix, and signal suppression at a high plant cell medium culture concentration (440 mg L-1) was verified; consequently, the accuracy for the mass-based concentration was found to be below 70%. However, at a low medium concentration (4.4 mg L-1), the recovery found for size, mass, and number-based concentration was higher than 80% for all nanoparticle sizes. A matrix-matching calibration was performed to overcome these interferences, and the accuracy was significantly improved. Examples of the application of spICP-MS, such as the estimation of silver nanoparticle stability in a plant cell liquid medium and silver fractionation in soybean callus samples after in vitro plant culture, were demonstrated. In conclusion, spICP-MS is an interesting and valuable approach in this research field, providing information regarding the interaction of plant cells and nanoparticles.