Controlled Release Chemistries

Nanofibrous polymeric seed coating for crop protection via electrospinning

Researchers: Tahira Pirzada, Barbara Vasconcelos de Ferias

Root knot nematodes are economically devastating parasites which are able to infect a wide variety of crops. Many commonly used nematicides suffer from poor target specificity and are often toxic and environmentally unsafe. Abamectin is a widely-used nematicide which has shown low toxicity to non-target organisms, with many studies supporting its safe agricultural use. Abamectin is typically applied to crops by spraying onto the soil surface; however, this route of application can tightly bind the Abamectin to the soil surface thereby making it unable to fully protect the root system beneath the surface. To address this issue, we have developed a method for more localized delivery of active components by coating soybean seeds with electrospun polymer nanofibers containing Abamectin. Electrospinning consists of applying an electrical field to a polymer solution to draw out fibers, which collect to form nonwoven mats. The fiber diameters are within the nanoscale range, causing the coatings to have a high surface-to-volume ratio that facilitates delivery applications.


Controlled release of pesticides for crop protection

Researchers: Tahira Pirzada, Barbara Vasconcelos de Ferias

We are also developing sustainable and affordable technology for crop protection from soil borne pathogens and pests for smallholder farmers in sub-Saharan Africa (SSA). Our work focuses on the management of plant-parasitic nematodes which are one of the major constraints on yield and production of food crops throughout the world. Our team is working on the development of a pulping process for manufacture of biodegradable matrix using locally available components to produce the seed wraps. In our ‘wrap and plant’ approach, we use pesticide loaded matrices as wraps for seeds to be planted in the soil. Initial experiments provide proof-of-concept for our ‘wrap and plant’ technology for seed treatment and demonstrate enhanced plant-parasitic nematode control in replicated trials both in USA and SSA.


Cyclodextrin for controlled drug release applications


The use of cyclodextrin-drug complexes in nanofibrous form offers a powerful method to enhance poorly water soluble molecules’ solubility while protecting the active material from degrading. However, cyclodextrin nanofibers dissolve instantly, limiting their use to sublingual delivery thus modification are needed extend the mat dissolution duration. We have shown that by blending cyclodextrin with different polymers and chemical crosslinking to extend the mat dissolution duration, we can allow the release of poorly water soluble drugs over an extended time period. In this case mat morphology and dissolution duration was altered by blending cyclodextrin with poly(vinyl alcohol) or chitosan and chemical crosslinking with glutaraldehyde. Both blending and crosslinking were found to alter the mat dissolution duration and affect the drug crystallinity and release profiles.