Efficiency of Biodegradable and pH-Responsive Nanoparticles As Smart Nano-Delivery Systems in Plants: In Vitro Cellular Investigation.

Using polymeric nanocarriers for the controlled release and site-specific delivery of various molecules, such as pesticides and nutrients, is potentially useful for agricultural applications. Characterizing the delivery efficiency of smart nano-delivery systems in plants is required to apply these systems to crop-specific problems.

In this work, the effects of polysuccinimide (PSI)-based nanoparticles (NPs) on cellular uptake efficiency of chemicals and microbial activity of soils were determined. PSI-NPs were synthesized and then their size measured by dynamic light scattering. NPs had an average size of 20.6 ± 0.6 nm with negative charges on the surface.

Particle loading capacity and pH-responsive release efficiency were determined with the fluorescent probe coumarine-6 and fluorescent spectroscopy. The loading capacity of the PSI-based NPs for coumarin-6 could be up to 30%. Release of the loaded chemical increased with increasing pH from 5.5 to 8.5 and reached 85% at pH~8.5.

Cellular uptake of the NPs into plant cells was determined using a grapefruit cell line. Uptake of coumarine-6-loaded NPs by grapefruit cells occurred within 10-30 min, indicating that the loaded NPs are able to enter plant cells.

Soil microbial toxicity of NPs was determined by counting colonies of microorganisms on culture plates after treating the soil with 200 ppm NPs for one week and by measuring soil respiration rates immediately after the spiking. No significant effects of NPs were observed on soil microbial activity.

These results suggest a potential feasibility of using nano-delivery systems for enhancing crop production systems. In addition, the PSI-based NPs are environmentally friendly, as evidenced by minimal effects on soil microbial activity.