(274h) Co-Encapsulation of a Metalloporphyrin in Agrochemical-Loaded Organic Nanocarriers for Tracking Translocation and Studying Nanocarrier-Plant Interactions

The use of organic nanocarriers (NCs) for efficient, targeted agrochemical delivery is a growing area of interest in precision agriculture. NC-mediated delivery enhances agrochemical internalization, translocation, tissue-specific targeting, and controlled release, while advances in nanoformulation processes like Flash NanoPrecipitation (FNP) streamline scalable production. However, a critical challenge in understanding NC–plant interactions is the lack of robust and reliable methods to track the transport and fate of organic NCs in planta. In this study, we propose a method to label NCs with a metal tracer for detection using inductively coupled plasma-mass spectrometry (ICP-MS), enabling tracking of NC movement in plants.

FNP was used to co-encapsulate a palladium-porphyrin complex (Pd(II) meso-tetraphenyl-tetrabenzoporphine) with a hydrophobic (esfenvalerate) or hydrophilic (streptomycin) active ingredient (AI). Core-shell NCs were formulated with three different shell materials (soy lecithin, polyethylene glycol, and hydroxypropyl methylcellulose acetate succinate), each designed to exhibit a distinct translocation profile. The resulting NCs ranged in hydrodynamic diameter from 75 to 100 nm with surface zeta potentials from -45 to 0 mV. After foliar application of the co-loaded NCs to tomato plants, translocation rates of palladium and AI were measured separately using ICP-MS and either GC-MS or LC-MS, depending on the analyte. Translocation behaviors between the two core components were compared and supported by in vitro release studies of AIs in simulated apoplastic fluid (SAF). Incubation of the NCs in SAF showed no leakage of the palladium tracer over weeks. This work demonstrates that metalloporphyrins can serve as proxies for NC distribution in planta, integrating seamlessly with current nanoformulation systems like FNP. This method enables simultaneous tracking of both NC and AI fate, providing valuable insights into particle biotransformation and AI release in planta.