Assessing the transport potential of polymeric nanocapsules developed for crop protection

Nanotechnology is increasingly important in the agricultural sector, with novel products being developed to heighten crop yields and increase pesticide efficacy. Herein, the transport potential of different polymeric nanocapsules (nCAPs) developed as pesticide delivery vehicles was assessed in model soil systems. The nCAPs examined are (i) poly(acrylic acid)-based (nCAP1), (ii) poly(methacrylic acid)-ran-poly(ethyl acrylate) copolymer-based (nCAP2), (iii) poly(methacrylic acid-ran-styrene) copolymer-based (nCAP3), and (iv) poly(methacrylic acid-ran-butylmethacrylate)-based (nCAP4). nCAP mobility was examined in columns packed with agricultural loamy sand saturated with artificial porewater containing Ca²⁺ and Mg²⁺ cations (10 mM ionic strength, pH 6 and 8). Furthermore, the impact of (i) cation species, (ii) sand type, and (iii) ammonium polyphosphate fertilizer on the transport potential of a nanoformulation combining nCAP4 capsules and the pyrethroid bifenthrin (nCAP4-BIF) was examined and compared to a commercial bifenthrin formulation (Capture^® LFR). Although nCAP4-BIF and Capture^® LFR formulations were highly mobile in quartz sand saturated with 10 mM NaNO₃ (≥95% elution), they were virtually immobile in the presence of 10% ammonium polyphosphate fertilizer. The presence of Ca²⁺ and Mg²⁺ did not hinder nCAP4-BIF elution in quartz sand saturated with 10 mM standard CIPAC D synthetic porewater; however, limited Capture^® LFR transport (<10% elution) was observed under the same conditions. Capture^® LFR also exhibited limited mobility in the presence or absence of fertilizer in loamy sand saturated with divalent salt solutions, whereas nCAP4-BIF exhibited increased elution with time and enhanced transport upon the addition of fertilizer. Overall, nCAP4 is a promising delivery vehicle in pyrethroid nanoformulations such as nCAP4-BIF.