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Developing plant adhesives opens opportunities for studying and optimizing plant growth through precision pesticide and nutrient delivery, plant health monitoring, and human-plant interaction. However, diverse and changing topologies and chemical compositions of plants during growth present challenges in designing effective and universal adhesives. In this study, we address this challenge by developing a gel composite consisting of a biopolymer that enables dynamic covalent bonding with plant surfaces and cross-linked polyacrylamide, which provides adaptability. This composite gel demonstrates strong yet reversible adhesion on both hairy and nonhairy plant surfaces. Its adhesion strength exceeds that of previously reported noninvasive plant adhesives by an order of magnitude. This achievement enables localized and sustained drug delivery to plant tissues and allows for stable plant actuation via electrical stimulation, opening pathways for modulating sensitive plant systems. 

The COVID-19 pandemic highlights the opportunity for mRNA vaccines and their nanotechnology carriers to make an impact as a countermeasure to infectious disease. As alternative to the synthetic lipid nanoparticles or mammalian viruses, we developed a tobacco mosaic virus (TMV)-based mRNA vaccine delivery platform. Specifically, purified coat protein from TMV was used to package a self-amplifying Nodamura replicon expressing the receptor binding domain (RBD) from the Omicron strain of SARS-CoV-2. The replicon construct contains the origin of assembly sequence from the tobacco mosaic virus (TMV) for encapsulation and mRNA stabilization. The nanoparticle vaccine was obtained through in vitro assembly using purified TMV coat proteins and in vitro transcribed mRNA cassettes. Cell assays confirmed delivery of self-amplifying mRNA vaccine, amplification of the transgene and expression of the target protein, RBD, in mammalian cells. Immunization of mice yielded RBDspecific IgG antibodies that demonstrated neutralization of SARS-CoV-2 using an in vitro neutralization assay. The TMV platform nanotechnology does not require ultralow freezers for storage or distribution; and the in vitro assembly method provide ‘plug-and-play’ to adapt the vaccine formulation rapidly as new strains or diseases emerge. Finally, opportunity exists to produce and self-assemble the vaccine candidate in plants through molecular farming techniques, which may allow production in the region-for the region and could make a contribution to less resourced areas of the world. 

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. 

Plant virus-like particles (VLPs) are biocompatible, non-infectious nanomaterials with promising applications as immunotherapeutics and vaccines. However, slow-release VLP formulations are needed to achieve long-term efficacy without repeated administration. VLP hydrogels allow the encapsulation and sustained delivery of VLPs, but the particles must covalently bind the hydrogel polymers to avoid premature loss. This has been achieved so far by in situ VLP polymerization, which requires high viral concentrations (5–10 mg/mL, 0.5–1 wt%) to form stable hybrid VLP–hydrogel networks and this complicates scalability and clinical translation. Here, we developed a novel swell-and-click method that led to successful VLP scaffold formation regardless of the viral load used. As a result, VLP-functionalized hydrogels were fabricated with viral concentrations as low as 0.1–1 mg/mL (0.01–0.1 % wt%) without compromising the scaffold stability on the process. The hydrogels incorporate VLPs during swelling, followed by copper-free click chemistry reactions that bind the particles covalently to the polymer. The swell-and-click method also resulted in more than a two-fold enhancement in VLP uptake into the hydrogels and it provides a means of combined burst release and prolonged sustained release, desired traits for cancer immunotherapy treatment. The present work introduces a novel methodology for the design of VLP-based hydrogels, which could facilitate the scalability of the fabrication process and move a significant step forward towards clinical translation of long-term VLP vaccination in cancer disease. 

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. 

In this work, we introduce a 3D-printable virus-like particle (VLP)-enhanced cross-linked biopolymer system.