June 15, 2020 – Biopolymer-based Nanofiber Seed Coatings: A Novel Approach to Enhance Agrichemical Delivery and Seedling Development



The inefficient delivery of agrichemicals (fertilizers and pesticides) in agri-food systems is linked to serious negative environmental health impacts. More specifically, it has been reported that 60-90% of applied fertilizers and pesticides are lost due to evaporation, degradation, and environmental run-off. Much of this inefficiency results from an inability to deliver the active ingredient at the right place (target), right time, and right dose. Furthermore, current estimates by Food and Agriculture Organization of the United Nations report that food production will need to increase by 70-100% by 2050 to sustain the current population growth. Achieving this level of productivity becomes more challenging given the negative pressure from increased environmental stresses such as drought, climate change, and net loss of arable soil. Consequently, novel strategies and innovative technologies for more efficient, targeted and precision agrichemical delivery are urgently needed across the “farm to fork” to sustainably solve the grand challenge of global food quality and security while minimizing environmental health impact.

An emerging research area in agrichemical delivery is the development of novel nano-enabled seed coating platforms for precise and targeted delivery of agrichemicals. Such seed coating approaches can be used to limit seed infection from microorganisms/pathogens during storage and germination, as well as to biofortify the seeds to enhance germination, seedling development and overall crop productivity. Currently, synthetic polymers such as polyvinyl alcohol and polyethylene glycol are employed as film coatings by industry using various approaches. However, such current film coating approaches can result in the formation of dense nonporous films which may limit the gas and water exchange, confounding seed germination and seedling development. In addition, most of the coating materials used in conventional approaches are typically dissolved in water and the active ingredients (e.g., pesticides, antimicrobial agents, fertilizer, micronutrients) are quickly released in an uncontrolled fashion. As a result, much of the active ingredients run off to the field, leading to low delivery efficiency and potentially significant negative environmental impacts.

Researchers at the Center for Nanotechnology and Nanotoxicology at the Harvard T.H. Chan School of Public Health (HCNN) led by Professor Philip Demokritou have recently been working on developing biopolymer-based nanoplatforms for targeted and precision agrichemical delivery as part of the Harvard-Nanyang Technological University/Singapore Sustainable Nanotechnology Initiative (https://healthtech.ntu.edu.sg/Research/CollaborationProgrammes/NTU-HSPH%20Initiative%20for%20Sustainable%20Nanotechnology/Pages/Home.aspx).

In this study just published at ACS Sustainable Chemistry and Engineering journal, researchers from HCNN and Connecticut Agriculture Experiment Station (CAES) developed a biodegradable, tunable, biopolymer-based nanofiber platform as seed coating to enhance agrichemical delivery and seedling development. The germination and subsequent growth of different nanofiber-coated seeds (tomato and lettuce) as a function of agrichemical release kinetics were investigated in greenhouse studies, in the presence or absence of a fungal pathogen (Fusarium species). Results from the greenhouse studies indicated the efficacy of such nano-enabled seed coating approach due to the precise delivery of agrichemical at the right place while utilizing a miniscule amount of agrichemical. The various Cu-release nanofiber coatings appeared to promote seed germination, particularly in the diseased media conditions. This more rapid germination led to increased seedling biomass for both plants (12-29%).

Tao Xu, a post-doctoral fellow and the lead author of the study remarked, “We synthesized these nanofiber coatings by using biopolymer blends without any toxic chemicals or post-treatment, and we can fine-tune the agrichemical release kinetics by modulating the polymer composition and hydrophilicity of nanofibers”.

Dr. Philip Demokritou, the center director concluded that “The developed nanofiber seed coating approach brings precision to agrichemical delivery and improves germination and seedling biomass for model seeds. Importantly, this platform can readily be exploited to deliver a whole range of micro- and macronutrients, as well as other analytes such as growth promoters or antimicrobial agents. Such seed nano-coating approach might also be used in pathogen infested soil conditions to increase production yields”.

The ACS Sustainable Chemistry and Engineering publication can be accessed here (https://pubs.acs.org/doi/abs/10.1021/acssuschemeng.0c02696). For more information on this and other nano-related research at the Harvard T.H. Chan School of Public Health, please visit our website at www.hsph.harvard.edu/nano.