Enhancing agrichemical delivery and plant development with biopolymer-based stimuli responsive nanoplatforms

J.C. White, Y. Wang, T. Xu, P. Demokritou
The Connecticut Agricultural Experiment Station,
United States

Keywords: agrichemical, nanoplatform, agri-food systems, food, nanospheres


The inefficient delivery of agrichemicals in agri-food systems is linked to serious negative planetary and public health impacts. Much of this inefficiency results from the inability to deliver the active ingredients at the right place (target), right time, and right dose. Consequently, novel strategies and innovative materials for efficient, targeted and precise agrichemical delivery are desperately needed across the “farm to fork” to sustainably solve the grand challenge of global food quality and security while minimizing environmental health impact. We are developing scalable, core-shell nanosphere platforms using electrospray of biopolymers based on green chemistry concepts. Such stimuli responsive nanospheres were then used for the smart delivery of model agrichemicals such as nitrogen, phosphorus, potassium and copper. A multi stimuli release strategy using both abiotic (pH) and biotic (enzymes secreted by plant pathogens) triggers was developed. Specifically, responsive core-shell nanospheres made from cellulose acetate/chitosan/zein/xtarch/PCL containing 25 mg NPK and 0.8 mg Cu were added to soils subsequently planted with soybean or wheat. Conventional fertilizer controls with NPK at 25 mg or 100 mg, either with or without Cu were included. During growth, the nanosphere with 25 mg NPK and Cu yielded significantly greater relative chlorophyll content in both species, which is an indirect measure of photosynthesis and productivity. The nanosphere values are equivalent to the conventional NPK at 100 mg (plus Cu), which has 4 times more NPK than our nanospheres. Similar results are evident in the activity of photosystem 1, which is another indicator of photosynthetic activity. Separately, LEF (linear electron flow) indicates the amount of energy that is being moved through the chloroplasts following exposure to light. In 5-week old wheat seedlings, nanospheres with 25 mg NPK and Cu exhibited a significantly greater LEF value than all other treatments, indicating enhanced electron flow and carbon fixation. Last, the Zn and Na content in the leaves of 5-week old soybean seedlings were significantly increased with nanosphere amendment, indicating that NPK and Cu in the this nanoscale form can potentially be used to modulate the accumulation of other important micronutrients through a potential biofortification strategy. Additional plant agronomic and molecular measurements are currently underway and will be presented. This interdisciplinary project represents a novel and significant advance in the development of precision sustainable agriculture.