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Abstract Delivery of agrochemicals into soil presents a challenge, as the active ingredients are often hydrophobic and do not possess adequate soil mobility to reach their target pest. Previously, plant virus nanoparticles have been shown to penetrate soil and deliver agrochemicals for the treatment of plant parasitic nematodes. For example, tobacco mild green mosaic virus (TMGMV) can be functionalized with agrochemicals through bioconjugation, infusion at the coat protein interface, or encapsulation through thermal shapeshifting (rod-to-sphere). There continues to be a need to expand approaches for agrochemical display and delivery with a need for plug-and-play technology to be applicable for multiple nanoparticle platforms and agrochemicals. Toward this goal, we turned toward a bio-specific coupling strategy making use of the biotin-(strept)avidin system. Herein, we conjugated TMGMV with either avidin or biotin using azide-alkyne cycloaddition. The avidin/biotin-functionalized TMGMV nanoparticles were then characterized by gel electrophoresis and electron microscopy to confirm cargo loading and the nanoparticle’s structural integrity. Soil column assays confirmed that soil mobility was maintained upon chemical modification. Ivermectin modified with biotin or streptavidin linkers was then introduced to the TMGMV-avidin/biotin nanoparticles and binding propensity and loading were validated by QCM-D and a competitive ELISA. Finally, the ivermectin-loaded TMGMV nanoparticles were used to treatC. elegansin a gel burrowing assay, demonstrating that either pesticide loading strategy resulted in active TMGMV nanoparticle formulation that significantly reduced the mobility of nematodes, even after passing through soil. In stark contrast, free ivermectin only exhibited efficacy when applied directly to nematodes; the free pesticide was lost in the soil column—highlighting the need for a delivery system. The presented approach provides a facile plug-and-play approach for pesticide loading onto TMGMV nanoparticles. In particular, biotinylated TMGMV with streptavidin-conjugated ivermectin served as the most effective formulation. Importantly this method does not require heat, which contrasts our previous method of thermal reshaping that requires sample and pesticide exposure to temperatures > 96 °C. We envision the bio-specific loading strategy could be extended to other protein or inorganic nanoparticles to advance soil treatment strategies.
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Inter-coat protein loading of active ingredients into Tobacco mild green mosaic virus through partial dissociation and reassembly of the virion
Abstract Chemical pesticide delivery is a fundamental aspect of agriculture. However, the extensive use of pesticides severely endangers the ecosystem because they accumulate on crops, in soil, as well as in drinking and groundwater. New frontiers in nano-engineering have opened the door for precision agriculture. We introduced Tobacco mild green mosaic virus (TMGMV) as a viable delivery platform with a high aspect ratio and favorable soil mobility. In this work, we assess the use of TMGMV as a chemical nanocarrier for agriculturally relevant cargo. While plant viruses are usually portrayed as rigid/solid structures, these are “dynamic materials,” and they “breathe” in solution in response to careful adjustment of pH or bathing media [e.g., addition of solvent such as dimethyl sulfoxide (DMSO)]. Through this process, coat proteins (CPs) partially dissociate leading to swelling of the nucleoprotein complexes—allowing for the infusion of active ingredients (AI), such as pesticides [e.g., fluopyram (FLP), clothianidin (CTD), rifampicin (RIF), and ivermectin (IVM)] into the macromolecular structure. We developed a “breathing” method that facilitates inter-coat protein cargo loading, resulting in up to ~ 1000 AIs per virion. This is of significance since in the agricultural setting, there is a need to develop nanoparticle delivery strategies where the AI is not chemically altered, consequently avoiding the need for regulatory and registration processes of new compounds. This work highlights the potential of TMGMV as a pesticide nanocarrier in precision farming applications; the developed methods likely would be applicable to other protein-based nanoparticle systems.
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- PAR ID:
- 10497045
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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