pH-Responsive Polymeric Nanoparticles for Controlled Delivery and Release in Agriculture

Release Encapsulated Pesticides Only Upon Contact with Increased Concentrations of Sugars or Elevated pH Levels

These nanoparticles release pesticides into the plant only upon contact with elevated concentrations of sugars or elevated pH levels found in the phloem. Citrus greening disease is one of the most serious citrus plant diseases in the world. There is no cure once a tree is infected, and the disease has put the future of America’s citrus crops at risk. Plants naturally have significantly elevated concentrations of sugar and pH in their phloem tissue, which is the main channel for moving sucralose and other metabolic products, as well as pesticides, from the leaves to the rest of the plant. Although pH-responsive materials have been extensively studied in the realm of medicine, few studies have applied such delivery methods within agriculture, despite the urgent need for specific delivery of pesticides and nutrients. Because only a small portion of their active compounds ever reach their targeted sites, pesticides frequently fail to kill harmful pathogens. Researchers at the University of Florida have created polymer nanoparticles that encapsulate pesticides and nutrients needed to combat plant disease, including citrus greening, and will only release these active compounds when elevated concentrations of sugar and pH are present in phloem tissue. This will enhance efficiency of agricultural fertilizers, nutrients, pesticides, antibiotics, and more.

Application

Nanoparticles that release pesticides only upon contact with elevated concentrations of sugars or elevated pH levels in phloem tissue.

Advantages

• Phloem-specific delivery releases active contents at the site where they are needed most, increasing the efficiency of pesticides, fertilizers, nutrients, and more
• Made with naturally occurring amino acids, creating polymers that are eco-friendly and degrade into harmless amino acid byproducts in soil
• Are amphiphilic in the presence of low concentrations of sugar and/or pH, ensuring an active payload isn’t released until it’s safely in the phloem tissue

Technology

Polymer nanoparticles will include a monomer with water-solubility that is dependent on the presence or absence of sugars and/or pH. The nanoparticles comprise both the responsive monomers units and additional hydrophilic units. Their sugar-responsive nature derives from boronic acid-containing polymers. Upon binding sugars to hydrophobic boronic acid units, the units become hydrophilic, thereby disrupting the amphiphilicity that allowed nanoparticle formation to originally occur and leading to release of hydrophobic compounds. The application method can be via injection or spraying.