Development of abamectin loaded plant virus nanoparticles for efficacious plant parasitic nematode control

Towards realizing nano-enabled precision delivery in plants

Nanocarriers (NCs) that can precisely deliver active agents, nutrients and genetic materials into plants will make crop agriculture more resilient to climate change and sustainable. As a research field, nano-agriculture is still developing, with significant scientific and societal barriers to overcome. In this Review, we argue that lessons can be learned from mammalian nanomedicine. In particular, it may be possible to enhance efficiency and efficacy by improving our understanding of how NC properties affect their interactions with plant surfaces and biomolecules, and their ability to carry and deliver cargo to specific locations. New tools are required to rapidly assess NC-plant interactions and to explore and verify the range of viable targeting approaches in plants. Elucidating these interactions can lead to the creation of computer-generated in silico models (digital twins) to predict the impact of different NC and plant properties, biological responses, and environmental conditions on the efficiency and efficacy of nanotechnology approaches. Finally, we highlight the need for nano-agriculture researchers and social scientists to converge in order to develop sustainable, safe and socially acceptable NCs.

Biochemical and nanotechnological approaches to combat phytoparasitic nematodes

The foundation of most food production systems underpinning global food security is the careful management of soil resources. Embedded in the concept of soil health is the impact of diverse soil-borne pests and pathogens, and phytoparasitic nematodes represent a particular challenge. Root-knot nematodes and cyst nematodes are severe threats to agriculture, accounting for annual yield losses of US$157 billion. The control of soil-borne phytoparasitic nematodes conventionally relies on the use of chemical nematicides, which can have adverse effects on the environment and human health due to their persistence in soil, plants, and water. Nematode-resistant plants offer a promising alternative, but genetic resistance is species-dependent, limited to a few crops, and breeding and deploying resistant cultivars often takes years. Novel approaches for the control of phytoparasitic nematodes are therefore required, those that specifically target these parasites in the ground whilst minimizing the impact on the environment, agricultural ecosystems, and human health. In addition to the development of next-generation, environmentally safer nematicides, promising biochemical strategies include the combination of RNA interference (RNAi) with nanomaterials that ensure the targeted delivery and controlled release of double-stranded RNA. Genome sequencing has identified more than 75 genes in root knot and cyst nematodes that have been targeted with RNAi so far. But despite encouraging results, the delivery of dsRNA to nematodes in the soil remains inefficient. In this review article, we describe the state-of-the-art RNAi approaches targeting phytoparasitic nematodes and consider the potential benefits of nanotechnology to improve dsRNA delivery.

Inter-coat protein loading of active ingredients into Tobacco mild green mosaic virus through partial dissociation and reassembly of the virion

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.

Pesticide Nanoformulations Based on Sunlight-Activated Controlled Release of Abamectin

A controlled release system that enables the sunlight-triggered release of a model agrochemical, abamectin (abm), is presented. The release system consists of polydopamine functionalized halloysite nanotubes (HNT-PDA) utilized as photothermal nanocarriers to encapsulate 25 wt % abm and 37 wt % lauric acid (LA), a phase change material, that acts as a heat-activable gatekeeper stopping or facilitating the abm release. When exposed to sunlight for 20 min at 1 and 3 sun light density, the temperature of the photothermal nanocarriers reaches 51 and 122 °C, respectively, which triggers the melting of LA and the consequent release of abm from the nanocarriers. Abm was shown to be released gradually over a period of 10 days when nanohybrids were exposed to sunlight for 6 h per day and to remain stable and kill Myzus persicae (Sulzer) (Hemiptera: Aphididae), green peach aphids, at a mortality rate of over 70% for at least 10 days. Aqueous dispersions of the LA/abm@HNT-PDA nanohybrids were studied in terms of their potential as aqueous sprayable pesticide nanoformulations and presented over 30% suspensibility, 36 mg/cm2 foliar retention, strong rainwater resistance, and a 50% mortality rate for M. persicae at a concentration of 9 mg/mL. The proposed sunlight-activated controlled release system based on photothermal, LA-functionalized HNT-PDA nanocarriers holds great potential as controlled release pesticide nanoformulations.

Tiny but Mighty: Nanoscale Materials in Plant Disease Management

Nanoscale materials are promising tools for managing plant diseases and are becoming important players in the current agritech revolution. However, adopting modern methodologies requires a broad understanding of their effectiveness in solving target problems and their effects on the environment and food chain. Furthermore, it is paramount that such technologies are mechanistically and economically feasible for growers to adopt in order to be sustainable in the long run. This Feature Article summarizes the latest findings on the role of nanoscale materials in managing agricultural plant pathogens. Herein, we discussed the benefits and limitations of using nanoscale materials in plant disease management and their potential impacts on the environment and global food security.

Can nanotechnology improve the application of bioherbicides?

Bioherbicides are composed of microorganisms or natural compounds and are used for weed control; however, they have specific weaknesses and constraints that hinder their development and success under field conditions. Nanotechnology can help to overcome these limitations by providing a good starting point for the design of specific formulations and carriers that minimize the deficiencies of natural compounds and microorganisms, such as low solubility, short shelf life or a loss of viability. In addition, nanoformulations can help to improve the efficacy of bioherbicides by increasing their effectiveness and bioavailability, reducing the amount required for a treatment, and enhancing their ability to target specific weeds while preserving the crop. However, it is important to choose the right materials and nanodevices depending on specific needs and considering several factors inherent to nanomaterials such as production cost, safety or possible toxic effects. © 2023 Society of Chemical Industry.

Green Biologics: Harnessing the Power of Plants to Produce Pharmaceuticals

Plants are increasingly used for the production of high-quality biological molecules for use as pharmaceuticals and biomaterials in industry. Plants have proved that they can produce life-saving therapeutic proteins (Elelyso™-Gaucher's disease treatment, ZMapp™-anti-Ebola monoclonal antibodies, seasonal flu vaccine, Covifenz™-SARS-CoV-2 virus-like particle vaccine); however, some of these therapeutic proteins are difficult to bring to market, which leads to serious difficulties for the manufacturing companies. The closure of one of the leading companies in the sector (the Canadian biotech company Medicago Inc., producer of Covifenz) as a result of the withdrawal of investments from the parent company has led to the serious question: What is hindering the exploitation of plant-made biologics to improve health outcomes? Exploring the vast potential of plants as biological factories, this review provides an updated perspective on plant-derived biologics (PDB). A key focus is placed on the advancements in plant-based expression systems and highlighting cutting-edge technologies that streamline the production of complex protein-based biologics. The versatility of plant-derived biologics across diverse fields, such as human and animal health, industry, and agriculture, is emphasized. This review also meticulously examines regulatory considerations specific to plant-derived biologics, shedding light on the disparities faced compared to biologics produced in other systems.

Nanobiosensors and nanoformulations in agriculture: new advances and challenges for sustainable agriculture

In the current scenario of climate change, global agricultural systems are facing remarkable challenges in order to increase production, while reducing the negative environmental impact. Nano-enabled technologies have the potential to revolutionise farming practices by increasing the efficiency of inputs and minimising losses, as well as contributing to sustainable agriculture. Two promising applications of nanotechnology in agriculture are nanobiosensors and nanoformulations (NFs). Nanobiosensors can help detect biotic and abiotic stresses in plants before they affect plant production, while NFs can make agrochemicals, more efficient and less polluting. NFs are becoming new-age materials with a wide variety of nanoparticle-based formulations such as fertilisers, herbicides, insecticides, and fungicides. They facilitate the site-targeted controlled delivery of agrochemicals enhancing their efficiency and reducing dosages. Smart farming aims to monitor and detect parameters related to plant health and environmental conditions in order to help sustainable agriculture. Nanobiosensors can provide real-time analytical data, including detection of nutrient levels, metabolites, pesticides, presence of pathogens, soil moisture, and temperature, aiding in precision farming practices, and optimising resource usage. In this review, we summarise recent innovative uses of NFs and nanobiosensors in agriculture that may boost crop protection and production, as well as reducing the negative environmental impact of agricultural activities. However, successful implementation of these smart technologies would require two special considerations: (i) educating farmers about appropriate use of nanotechnology, (ii) conducting field trials to ensure effectiveness under real conditions.

Multifunctional plant virus nanoparticles: An emerging strategy for therapy of cancer

Cancer therapy requires sophisticated treatment strategies to obtain the highest success. Nanotechnology is enabling, revolutionizing, and multidisciplinary concepts to improve conventional cancer treatment modalities. Nanomaterials have a central role in this scenario, explaining why various nanomaterials are currently being developed for cancer therapy. Viral nanoparticles (VNPs) have shown promising performance in cancer therapy due to their unique features. VNPs possess morphological homogeneity, ease of functionalization, biocompatibility, biodegradability, water solubility, and high absorption efficiency that are beneficial for cancer therapy applications. In the current review paper, we highlight state-of-the-art properties and potentials of plant viruses, strategies for multifunctional plant VNPs formulations, potential applications and challenges in VNPs-based cancer therapy, and finally practical solutions to bring potential cancer therapy one step closer to real applications. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Biocontrol Efficacy of Bacillus methylotrophicus TA-1 Against Meloidogyne incognita in Tomato

Root-knot nematodes (RKNs) are harmful plant-parasitic nematodes of tomatoes which can cause significant yield losses. Therefore, there is increasing interest in exploring the application of bacterial nematicides. The bacterium Bacillus methylotrophicus TA-1 is a broad-spectrum biological control agent; however, its effect on RKNs control remains largely unclear. In this study, the toxicity of B. methylotrophicus TA-1 against Meloidogyne incognita was investigated in vitro, and the potential of B. methylotrophicus TA-1 to decrease infection of RKNs in tomato were evaluated in pot and field trials. Results showed that B. methylotrophicus TA-1 exhibited high nematicidal activity against second-stage juveniles (J2s) and eggs of M. incognita with 50% lethal concentration (LC50) values of 5.80 and 7.00 × 108 colony forming units (CFU)/ml, respectively. In the pot experiments and field trials conducted in 2020 and 2021, tomato plants treated with B. methylotrophicus TA-1 soil drench applied once at 3, 6, and 9 × 108 CFU/plant had significantly higher plant height and greater yield compared with the untreated control. Tomato yields of the treated plots with B. methylotrophicus TA-1 in 2 consecutive years' field trials were between 53.4 to 66.1 and 52.8 to 61.5 t/ha, while they were 49.7 and 48.2 t/ha in the untreated control for each year, respectively. The lowest population densities of M. incognita at 30 and 60 days after treatment were 119 and 135 J2s per 100 g soil in 2020 and 43 and 118 J2s in 2021 in TA-1-treated plots. The lowest gall index of 4.7 and 3.3 in 2020 and 2021, respectively, and the highest yield were all observed in the TA-1 at 9 × 108 CFU/plant treated plants, with no significant differences with the commercial control abamectin. These results provided a basis for further studies of B. methylotrophicus TA-1 formulations, application doses, frequencies, and mechanisms of action, which are necessary before it could be used as a component of integrated management programs to manage RKNs in tomato production.

The effect of abamectin application in combination with agronomic measures on the control efficacy of cucumber root-knot nematodes and the cucumber yield

BACKGROUND

As a registered non-fumigant nematicide, abamectin has been widely used as a soil treatment against many cash crop nematode diseases. In a previous study, we found that soil adsorption hindered the stable performance of abamectin against root-knot nematodes in the field.

RESULTS

In this study, an efficient and labor-saving application method of soil blending abamectin combined with rotary tillage, a common agronomic measure, was developed to improve the efficacy of abamectin against root-knot nematode disease. We revealed the role of four parameters in this application method. At an abamectin dose of 750 g a.i. ha-1 , spray water volume of 675 L ha-1 and rotation depth of 20 cm, abamectin was well distributed in the 0-20 cm soil layer at a concentration of 0.41-0.46 mg kg-1 , the efficacy against root-knot nematode disease was 72.12%, and the cucumber yield was 51.93 t ha-1 . At the same dosage, root irrigation and flood irrigation measures resulted in only 29.28% and 33.43% control, with cucumber yields of 42.96 and 44.73 t ha-1 , respectively.

CONCLUSION

To control root-knot nematode disease with abamectin, a soil blending application combined with rotary tilling is superior to leaching application combined with the agronomic measure of irrigation. The former application method can improve the dispersion of abamectin in the soil, enhance the efficacy of abamectin against root-knot nematodes and maintain a stable cucumber yield. In addition, the increased labor required for application combined with agronomic measures is negligible and has excellent application prospects. © 2023 Society of Chemical Industry.

One-pot construction of epoxy resin nanocarrier delivering abamectin and its efficacy on plant root-knot nematodes

BACKGROUND

The complex preparation process and storage instability of nanoformulations hinders their development and commercialization. In this study, nanocapsules loaded with abamectin were prepared by interfacial polymerization at room temperature and ordinary pressure using the monomers of epoxy resin (ER) and diamine. The potential mechanisms of primary amine and tertiary amine in influencing the shell strength of the nanocapsules and the dynamic stability of abamectin nanocapsules (Aba@ER) in the suspension system were systematically researched.

RESULTS

The tertiary amine catalyzed the self-polymerization of epoxy resin into linear macromolecules with unstable structures. The structural stability of the diamine curing agent with a primary amine group played a key role in enhancing the structural stability of the polymers. The intramolecular structure of the nanocapsule shell formed by isophorondiamine (IPDA) crosslinked epoxy resin has multiple spatial conformations and a rigid saturated six-membered ring. Its structure was stable, and the shell strength was strong. The formulation had stable dynamic changes during storage and maintained excellent biological activity. Compared with emulsifiable concentrate (EC), Aba@ER/IPDA had superior biological activity, and the field efficacy on tomato root-knot nematode was enhanced by approximately 31.28% at 150 days after transplanting.

CONCLUSION

Aba@ER/IPDA, which has excellent storage stability and simple preparation technology, can provide a nanoplatform with industrial prospects for efficient pesticide delivery. © 2023 Society of Chemical Industry.

Delivery of Nematicides Using TMGMV-Derived Spherical Nanoparticles

Spherical nanoparticles (SNPs) from tobacco mild green mosaic virus (TMGMV) were developed and characterized, and their application for agrochemical delivery was demonstrated. Specifically, we set out to develop a platform for pesticide delivery targeting nematodes in the rhizosphere. SNPs were obtained by thermal shape-switching of the TMGMV. We demonstrated that cargo can be loaded into the SNPs during thermal shape-switching, enabling the one-pot synthesis of functionalized nanocarriers. Cyanine 5 and ivermectin were encapsulated into SNPs to achieve 10% mass loading. SNPs demonstrated good mobility and soil retention slightly higher than that of TMGMV rods. Ivermectin delivery to Caenorhabditis elegans using SNPs was determined after passing the formulations through soil. Using a gel burrowing assay, we demonstrate the potent efficacy of SNP-delivered ivermectin against nematodes. Like many pesticides, free ivermectin is adsorbed in the soil and did not show efficacy. The SNP nanotechnology offers good soil mobility and a platform technology for pesticide delivery to the rhizosphere.

Preparation of enzyme-responsive composite nanocapsules with sodium carboxymethyl cellulose to improve the control effect of root-knot nematode disease

Developing an efficient drug delivery system to mitigate the harm caused by root-knot nematodes is crucial. In this study, enzyme-responsive release abamectin nanocapsules (AVB1a NCs) were prepared using 4, 4-diphenylmethane diisocyanate (MDI) and sodium carboxymethyl cellulose as response release factors. The results showed that the average size (D₅₀₎ of the AVB1a NCs was 352 nm, and the encapsulation efficiency was 92 %. The median lethal concentration (LC₅₀) of AVB1a NCs for Meloidogyne incognita activity was 0.82 mg L^-1. Moreover, AVB1a NCs improved the permeability of AVB1a to root-knot nematodes and plant roots and the horizontal and vertical soil mobility. Furthermore, AVB1a NCs greatly reduced the adsorption of AVB1a by the soil compared to AVB1a emulsifiable concentrate (EC), and the effect of the AVB1a NCs on controlling root-knot nematode disease was increased by 36 %. Compared to the AVB1a EC, the pesticide delivery system significantly reduced the acute toxicity to the soil biological earthworms by approximately 16 times that of the AVB1a and had a lower overall impact on the soil microbial communities. This enzyme-responsive pesticide delivery system had a simple preparation method, excellent performance, and high level of safety, and thus has great application potential for plant diseases and insect pests control.

Multifunctional Metal-Organic Framework (MOF)-Based Nanoplatforms for Crop Protection and Growth Promotion

Phytopathogen, pest, weed, and nutrient deficiency cause severe losses to global crop yields every year. As the core engine, agrochemicals drive the continuous development of modern agriculture to meet the demand for agricultural productivity and increase the environmental burden due to inefficient use. With new advances in nanotechnology, introducing nanomaterials into agriculture to realize agrochemical accurate and targeted delivery has brought new opportunities to support the sustainable development of green agriculture. Metal-Organic frameworks (MOFs), which weave metal ions/clusters and organic ligands into porous frameworks, have exhibited significant advantages in constructing biotic/abiotic stimuli-responsive nanoplatforms for controlled agrochemical delivery. This review emphasizes the recent developments of MOF-based nanoplatforms for crop protection, including phytopathogen, pest, and weed control, and crop growth promotion, including fertilizer/plant hormone delivery. Finally, forward-looking perspectives and challenges on MOF-based nanoplatforms for future applications in crop protection and growth promotion are also discussed.

Harnessing plant viruses in the metagenomics era: from the development of infectious clones to applications

Recent metagenomic studies which focused on virus characterization in the entire plant environment have revealed a remarkable viral diversity in plants. The exponential discovery of viruses also requires the concomitant implementation of high-throughput methods to perform their functional characterization. Despite several limitations, the development of viral infectious clones remains a method of choice to understand virus biology, their role in the phytobiome, and plant resilience. Here, we review the latest approaches for efficient characterization of plant viruses and technical advances built on high-throughput sequencing and synthetic biology to streamline assembly of viral infectious clones. We then discuss the applications of plant viral vectors in fundamental and applied plant research as well as their technical and regulatory limitations, and we propose strategies for their safer field applications.

Enzyme-Responsive Lignin Nanocarriers for Triggered Delivery of Abamectin to Control Plant Root-Knot Nematodes (Meloidogyne incognita)

Intelligently responsive nanoparticles can improve insecticidal activity against target organisms and reduce the use of pesticides in agriculture. In this study, enzymatic hydrolysis lignin (EHL) nanocarriers with enzyme responsiveness were successfully prepared by electrostatic interaction, and abamectin (Abm)-loaded EHL-based nanoparticles (Abm@L-CL) were investigated. The release behavior of Abm@L-CL nanoparticles showed that Abm was released rapidly in the presence of cellulase and pectinase but slowly under natural conditions. The insecticidal activity of Abm@L-CL treatment (LC₅₀ = 0.68 μg/mL) against nematodes (Meloidogyne incognita) was significantly more effective than that of original Abm treatment (LC₅₀ = 1.32 μg/mL). The mortality rate of Abm@L-CL was more than 90% by applying the same dose of Abm after 12 h. The bioactivity of Abm@L-CL against root-knot nematodes was 1.7-fold greater than that of Abm. The result of fluorescence indicated that nanoparticles could enter the intestinal tract through the oral cavity of nematodes and achieve obvious gastric toxicity. Furthermore, the enzyme-controlled lignin-based Abm nanocarriers could penetrate the tomato root near the elongation zone. This study provided intelligent enzyme-responsive nanocarriers for efficient management of soil-borne diseases and pests in green agricultural inputs.

Hemicelluloses-based sprayable and biodegradable pesticide mulch films for Chinese cabbage growth

In this study, one high-performance hemicelluloses (HC)-based sprayable and biodegradable pesticide mulch film was developed. Firstly, HC was transesterified with vinyl acetate (VA) to improve its solubility and film-forming ability. Then abamectin (ABA) was encapsulated by β-cyclodextrin (β-CD) to endow mulch film persistent anti-pesticide activity. After that, sodium alginate (SA) and gelatin were added to develop the mechanical performances of the mulch film. As a result, the obtained mulch film showed good characteristics, with optimum mechanical strength, elongation at break, water vapor permeability (WVP), swelling ratio (SR), and weight loss (biodegradability) of 7.9 ± 0.3 MPa, 43.6 ± 2.0 %, 2.1 ± 0.1 × 10^-11 g mm m^-2 s^-1 kPa^-1, 73.8 ± 2.0 %, and 69.3 %, respectively. After covering with mulch film, the soil moisture and temperature were developed to 90.8 % and 19.3 ± 0.2 °C, respectively, which could facilitate Chinese cabbage growth, with optimum germination rate of 98.6 ± 6.4 %.

Production of cytoplasmic type citrus leprosis virus-like particles by plant molecular farming

Many plant virus-like particles (VLPs) utilized in nanotechnology are 30-nm icosahedrons. To expand the VLP platforms, we produced VLPs of Cytoplasmic type citrus leprosis virus (CiLV-C) in Nicotiana benthamiana. We were interested in CiLV-C because of its unique bacilliform shape (60-70 nm × 110-120 nm). The CiLV-C capsid protein (p29) gene was transferred to the pTRBO expression vector transiently expressed in leaves. Stable VLPs were formed, as confirmed by agarose gel electrophoresis, transmission electron microscopy and size exclusion chromatography. Interestingly, the morphology of the VLPs (15.8 ± 1.3 nm icosahedral particles) differed from that of the native bacilliform particles indicating that the assembly of native virions is influenced by other viral proteins and/or the packaged viral genome. The smaller CiLV-C VLPs will also be useful for structure-function studies to compare with the 30-nm icosahedrons of other VLPs.

Bioconjugation Strategies for Tobacco Mild Green Mosaic Virus

Tobacco mild green mosaic virus (TMGMV) is a plant virus closely related to Tobacco mosaic virus (TMV), sharing many of its structural and chemical features. These rod-shaped viruses, comprised of 2130 identical coat protein subunits, have been utilized as nanotechnological platforms for a myriad of applications, ranging from drug delivery to precision agriculture. This versatility for functionalization is due to their chemically active external and internal surfaces. While both viruses are similar, they do exhibit some key differences in their surface chemistry, suggesting the reactive residue distribution on TMGMV should not overlap with TMV. In this work, we focused on the establishment and refinement of chemical bioconjugation strategies to load molecules into or onto TMGMV for targeted delivery. A combination of NHS, EDC, and diazo coupling reactions in combination with click chemistry were used to modify the N-terminus, glutamic/aspartic acid residues, and tyrosines in TMGMV. We report loading with over 600 moieties per TMGMV via diazo-coupling, which is a >3-fold increase compared to previous studies. We also report that cargo can be loaded to the solvent-exposed N-terminus and carboxylates on the exterior/interior surfaces. Mass spectrometry revealed the most reactive sites to be Y12 and Y72, both tyrosine side chains are located on the exterior surface. For the carboxylates, interior E106 (66.53 %) was the most reactive for EDC-propargylamine coupled reactions, with the exterior E145 accounting for >15 % reactivity, overturning previous assumptions that only interior glutamic acid residues are accessible. A deeper understanding of the chemical properties of TMGMV further enables its functionalization and use as a multifunctional nanocarrier platform for applications in medicine and precision farming.

Protein Cages: From Fundamentals to Advanced Applications

Proteins that self-assemble into polyhedral shell-like structures are useful molecular containers both in nature and in the laboratory. Here we review efforts to repurpose diverse protein cages, including viral capsids, ferritins, bacterial microcompartments, and designed capsules, as vaccines, drug delivery vehicles, targeted imaging agents, nanoreactors, templates for controlled materials synthesis, building blocks for higher-order architectures, and more. A deep understanding of the principles underlying the construction, function, and evolution of natural systems has been key to tailoring selective cargo encapsulation and interactions with both biological systems and synthetic materials through protein engineering and directed evolution. The ability to adapt and design increasingly sophisticated capsid structures and functions stands to benefit the fields of catalysis, materials science, and medicine.

Degradable Bactericide Constructed Using a Charge-Reversal Surfactant against Plant Pathogenic Bacteria

Plant bacterial diseases are serious problems in agriculture, posing threats to global food security and the agricultural economy. Here, a degradable agricultural bactericide AMC-10 constructed using a charge-reversal surfactant, from being positively charged to negatively charged, was designed and synthesized. AMC-10 possessed high bactericidal activity toward plant pathogenic bacteria, consequently being able to inhibit the corresponding plant bacterial diseases. After degradation by water, the hydrolyzed products were nontoxic to bacteria and human cells. Such a degradable bactericide provides new ideas for the design of environmentally friendly agricultural bactericides. It is anticipated that degradable bactericides such as AMC-10 can be applied in the prevention and control of plant bacterial diseases, being less likely to produce toxicity or drug resistance.

Wheat Root Protection From Cereal Cyst Nematode (Heterodera avenae) by Fluopyram Seed Treatment

Cereal cyst nematode (Heterodera avenae), an important plant-parasitic nematode causing yield losses of wheat, has been found in many provinces in China. It is urgent to develop an effective method of protecting wheat from H. avenae damage. Because of its novel mode of action, fluopyram has been registered for controlling root-knot nematodes on cucumber and tomato in China. However, the bioactivity of fluopyram against H. avenae and whether this seed treatment can effectively control H. avenae on wheat remains unknown. In this study, a bioactivity assay revealed that fluopyram increased the mortality of H. avenae second-stage juveniles (J2), with lethal concentrations (LC) required to kill 50% (LC50) and 90% (LC90) of 0.92 mg⋅liter^-1 and 2.92 mg⋅liter^-1_, respectively. Hatching tests showed that the H. avenae egg hatching percent was reduced by 35.2 to 69.2% with fluopyram at rates of 1.6 to 6.4 mg⋅liter^-1, and that the egg hatching period was delayed by 3 to 9 days compared with the control. During pot and field trials, fluopyram seed treatment significantly reduced the H. avenae population density and increased wheat yield by 3.0 to 13.7%. Therefore, fluopyram seed treatment is an effective approach for the management of H. avenae on wheat in China.

Nanotechnological Applications Based on Bacterial Encapsulins

Encapsulins are proteinaceous nanocontainers, constructed by a single species of shell protein that self-assemble into 20-40 nm icosahedral particles. Encapsulins are structurally similar to the capsids of viruses of the HK97-like lineage, to which they are evolutionarily related. Nearly all these nanocontainers encase a single oligomeric protein that defines the physiological role of the complex, although a few encapsulate several activities within a single particle. Encapsulins are abundant in bacteria and archaea, in which they participate in regulation of oxidative stress, detoxification, and homeostasis of key chemical elements. These nanocontainers are physically robust, contain numerous pores that permit metabolite flux through the shell, and are very tolerant of genetic manipulation. There are natural mechanisms for efficient functionalization of the outer and inner shell surfaces, and for the in vivo and in vitro internalization of heterologous proteins. These characteristics render encapsulin an excellent platform for the development of biotechnological applications. Here we provide an overview of current knowledge of encapsulin systems, summarize the remarkable toolbox developed by researchers in this field, and discuss recent advances in the biomedical and bioengineering applications of encapsulins.

Eco-Friendly Nanoplatforms for Crop Quality Control, Protection, and Nutrition

Agricultural chemicals have been widely utilized to manage pests, weeds, and plant pathogens for maximizing crop yields. However, the excessive use of these organic substances to compensate their instability in the environment has caused severe environmental consequences, threatened human health, and consumed enormous economic costs. In order to improve the utilization efficiency of these agricultural chemicals, one strategy that attracted researchers is to design novel eco-friendly nanoplatforms. To date, numerous advanced nanoplatforms with functional components have been applied in the agricultural field, such as silica-based materials for pesticides delivery, metal/metal oxide nanoparticles for pesticides/mycotoxins detection, and carbon nanoparticles for fertilizers delivery. In this review, the synthesis, applications, and mechanisms of recent eco-friendly nanoplatforms in the agricultural field, including pesticides and mycotoxins on-site detection, phytopathogen inactivation, pest control, and crops growth regulation for guaranteeing food security, enhancing the utilization efficiency of agricultural chemicals and increasing crop yields are highlighted. The review also stimulates new thinking for improving the existing agricultural technologies, protecting crops from biotic and abiotic stress, alleviating the global food crisis, and ensuring food security. In addition, the challenges to overcome the constrained applications of functional nanoplatforms in the agricultural field are also discussed.

Ecotoxicological and regulatory aspects of environmental sustainability of nanopesticides

Recent years have seen the development of various colloidal formulations of pesticides and other agrochemicals aimed at use in sustainable agriculture. These formulations include inorganic, organic or hybrid particulates, or nanocarriers composed of biodegradable polymers, that can provide a better control of the release of active ingredients. The very small particle sizes and high surface areas of nanopesticides may however also lead to some unintended (eco)toxicological effects due to the way in which they interact with the target and non-target species and the environment. The current level of knowledge on ecotoxicological effects of nanopesticides is scarce, especially in regard to the fate and behaviour of such formulations in the environment. Nanopesticides will however have to cross a stringent regulatory scrutiny before marketing in most countries for health and environmental risks under a range of regulatory frameworks that require pre-market notification, risk assessment and approval, followed by labelling, post-market monitoring and surveillance. This review provides an overview of the key regulatory and ecotoxicological aspects relating to nanopesticides that will need to be considered for environmentally-sustainable use in agriculture.

Lignin-Modified Electronegative Epoxy Resin Nanocarriers Effectively Deliver Pesticides against Plant Root-Knot Nematodes (Meloidogyne incognita)

It is highly desirable to fabricate a pesticide delivery system with excellent permeability to reduce the damage caused by root-knot nematodes in the soil. In this work, a novel electronegative pesticide nanocarrier was established by bonding anionic lignosulfonate with epoxy resin nanocarriers, which were loaded with abamectin (Aba). The results demonstrated that nanoparticles were negatively charged (-38.4 mV) spheres with an average size of 150 nm, and the encapsulation efficiency of nanocarriers for Aba was 93.4%. Polymer nanocarriers could prevent premature release of Aba and protect active ingredients from microbiological degradation. The adsorption strength of the soil to Aba loaded in nanocarriers was reduced by 6 to 10 times, so nanonematicides have remarkable soil mobility. Meanwhile, nanoparticles could easily penetrate the roots and nematodes. The application test confirmed that the control effect of this nanopesticide was 26-40% higher than that of the other agrochemicals. In consideration of its superior bioactivity and utilization rate, this pesticide delivery system has promising potential to control root-knot nematodes and improve the pesticide's utilization efficiency.

Viruses of protozoan parasites and viral therapy: Is the time now right?

Infections caused by protozoan parasites burden the world with huge costs in terms of human and animal health. Most parasitic diseases caused by protozoans are neglected, particularly those associated with poverty and tropical countries, but the paucity of drug treatments and vaccines combined with increasing problems of drug resistance are becoming major concerns for their control and eradication. In this climate, the discovery/repurposing of new drugs and increasing effort in vaccine development should be supplemented with an exploration of new alternative/synergic treatment strategies. Viruses, either native or engineered, have been employed successfully as highly effective and selective therapeutic approaches to treat cancer (oncolytic viruses) and antibiotic-resistant bacterial diseases (phage therapy). Increasing evidence is accumulating that many protozoan, but also helminth, parasites harbour a range of different classes of viruses that are mostly absent from humans. Although some of these viruses appear to have no effect on their parasite hosts, others either have a clear direct negative impact on the parasite or may, in fact, contribute to the virulence of parasites for humans. This review will focus mainly on the viruses identified in protozoan parasites that are of medical importance. Inspired and informed by the experience gained from the application of oncolytic virus- and phage-therapy, rationally-driven strategies to employ these viruses successfully against parasitic diseases will be presented and discussed in the light of the current knowledge of the virus biology and the complex interplay between the viruses, the parasite hosts and the human host. We also highlight knowledge gaps that should be addressed to advance the potential of virotherapy against parasitic diseases.

Plant viral nanoparticles for packaging and in vivo delivery of bioactive cargos

Nanoparticles have unique capabilities and considerable promise for many different biological uses. One capability is delivering bioactive cargos to specific cells, tissues, or organisms. Depending on the task, there are multiple variables to consider including nanoparticle selection, targeting strategies, and incorporating cargo so it can be delivered in a biologically active form. One nanoparticle option, genetically controlled plant viral nanoparticles (PVNPs), is highly uniform within a given virus but quite variable between viruses with a broad range of useful properties. PVNPs are flexible and versatile tools for incorporating and delivering a wide range of small or large molecule cargos. Furthermore, PVNPs can be modified to create nanostructures that can solve problems in medical, environmental, and basic research. This review discusses the currently available techniques for delivering bioactive cargos with PVNPs and potential cargos that can be delivered with these strategies. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Tailored Lignocellulose-Based Biodegradable Matrices with Effective Cargo Delivery for Crop Protection

Controlled release and targeted delivery of agrochemicals are crucial for achieving effective crop protection with minimal damage to the environment. This work presents an innovative and cost-effective approach to fabricate lignocellulose-based biodegradable porous matrices capable of slow and sustained release of the loaded molecules for effective crop protection. The matrix exhibits tunable physicochemical properties which, when coupled with our unique "wrap-and-plant" concept, help to utilize it as a defense against soil-borne pests while providing controlled release of crop protection moieties. The tailored matrix is produced by mechanical treatment of the lignocellulosic fibers obtained from banana plants. The effect of different extents of mechanical treatments of the lignocellulosic fibers on the protective properties of the developed matrices is systematically investigated. While variation in mechanical treatment affects the morphology, strength, and porosity of the matrices, the specific composition and structure of the fibers are also capable of influencing their release profile. To corroborate this hypothesis, the effect of morphology and lignin content changes on the release of rhodamine B and abamectin as model cargos is investigated. These results, compared with those of the matrices developed from non-banana fibrous sources, reveal a unique release profile of the matrices developed from banana fibers, thereby making them strong candidates for crop protection applications.

The biomedical and bioengineering potential of protein nanocompartments

Protein nanocompartments (PNCs) are self-assembling biological nanocages that can be harnessed as platforms for a wide range of nanobiotechnology applications. The most widely studied examples of PNCs include virus-like particles, bacterial microcompartments, encapsulin nanocompartments, enzyme-derived nanocages (such as lumazine synthase and the E2 component of the pyruvate dehydrogenase complex), ferritins and ferritin homologues, small heat shock proteins, and vault ribonucleoproteins. Structural PNC shell proteins are stable, biocompatible, and tolerant of both interior and exterior chemical or genetic functionalization for use as vaccines, therapeutic delivery vehicles, medical imaging aids, bioreactors, biological control agents, emulsion stabilizers, or scaffolds for biomimetic materials synthesis. This review provides an overview of the recent biomedical and bioengineering advances achieved with PNCs with a particular focus on recombinant PNC derivatives.

Nanocarriers for the Delivery of Medical, Veterinary, and Agricultural Active Ingredients

Nanocarrier-based delivery systems can be used to increase the safety and efficacy of active ingredients in medical, veterinary, or agricultural applications, particularly when such ingredients are unstable, sparingly soluble, or cause off-target effects. In this review, we highlight the diversity of nanocarrier materials and their key advantages compared to free active ingredients. We discuss current trends based on peer-reviewed research articles, patent applications, clinical trials, and the nanocarrier formulations already approved by regulatory bodies. Although most nanocarriers have been engineered to combat cancer, the number of formulations developed for other purposes is growing rapidly, especially those for the treatment of infectious diseases and parasites affecting humans, livestock, and companion animals. The regulation and prohibition of many pesticides have also fueled research to develop targeted pesticide delivery systems based on nanocarriers, which maximize efficacy while minimizing the environmental impact of agrochemicals.

From stars to stripes: RNA-directed shaping of plant viral protein templates-structural synthetic virology for smart biohybrid nanostructures

The self-assembly of viral building blocks bears exciting prospects for fabricating new types of bionanoparticles with multivalent protein shells. These enable a spatially controlled immobilization of functionalities at highest surface densities-an increasing demand worldwide for applications from vaccination to tissue engineering, biocatalysis, and sensing. Certain plant viruses hold particular promise because they are sustainably available, biodegradable, nonpathogenic for mammals, and amenable to in vitro self-organization of virus-like particles. This offers great opportunities for their redesign into novel "green" carrier systems by spatial and structural synthetic biology approaches, as worked out here for the robust nanotubular tobacco mosaic virus (TMV) as prime example. Natural TMV of 300 x 18 nm is built from more than 2,100 identical coat proteins (CPs) helically arranged around a 6,395 nucleotides ssRNA. In vitro, TMV-like particles (TLPs) may self-assemble also from modified CPs and RNAs if the latter contain an Origin of Assembly structure, which initiates a bidirectional encapsidation. By way of tailored RNA, the process can be reprogrammed to yield uncommon shapes such as branched nanoobjects. The nonsymmetric mechanism also proceeds on 3'-terminally immobilized RNA and can integrate distinct CP types in blends or serially. Other emerging plant virus-deduced systems include the usually isometric cowpea chlorotic mottle virus (CCMV) with further strikingly altered structures up to "cherrybombs" with protruding nucleic acids. Cartoon strips and pictorial descriptions of major RNA-based strategies induct the reader into a rare field of nanoconstruction that can give rise to utile soft-matter architectures for complex tasks. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Safe nanotechnologies for increasing the effectiveness of environmentally friendly natural agrochemicals

Natural compounds and living organisms continue to play a limited role in crop protection, and few of them have reached the market, despite their attractiveness and the efforts made in research. Very often these products have negative characteristics compared to synthetic compounds, e.g., higher costs of production, lower effectiveness, lack of persistence, and inability to reach and penetrate the target plant. Conversely, nanotechnologies are having an enormous impact on all human activities, including agriculture, even if the production of some nanomaterials is not environmentally friendly or could have adverse effects on agriculture and the environment. Thus, certain nanomaterials could facilitate the development of formulated natural pesticides, making them more effective and more environmentally friendly. Nanoformulations can improve efficacy, reduce effective doses, and increase shelf-life and persistence. Such controlled-release products can improve delivery to the target pest. This review considers certain available nanomaterials and nanotechnologies for use in agriculture, discussing their properties and the feasibility of their use in sustainable crop protection, in particular, in improving the effectiveness of natural bio-based agrochemicals. © 2019 Society of Chemical Industry.

Soil mobility of synthetic and virus-based model nanopesticides

Large doses of chemical pesticides are required to achieve effective concentrations in the rhizosphere, which results in the accumulation of harmful residues. Precision farming is needed to improve the efficacy of pesticides, but also to avoid environmental pollution, and slow-release formulations based on nanoparticles offer one solution. Here, we tested the mobility of synthetic and virus-based model nanopesticides by combining soil column experiments with computational modelling. We found that the tobacco mild green mosaic virus and cowpea mosaic virus penetrate soil to a depth of at least 30 cm, and could therefore deliver nematicides to the rhizosphere, whereas the Physalis mosaic virus remains in the first 4 cm of soil and would be more useful for the delivery of herbicides. Our experiments confirm that plant viruses are superior to synthetic mesoporous silica nanoparticles and poly(lactic-co-glycolic acid) for the delivery and controlled release of pesticides, and could be developed as the next generation of pesticide delivery systems.

Harnessed viruses in the age of metagenomics and synthetic biology: an update on infectious clone assembly and biotechnologies of plant viruses

Recent metagenomic studies have provided an unprecedented wealth of data, which are revolutionizing our understanding of virus diversity. A redrawn landscape highlights viruses as active players in the phytobiome, and surveys have uncovered their positive roles in environmental stress tolerance of plants. Viral infectious clones are key tools for functional characterization of known and newly identified viruses. Knowledge of viruses and their components has been instrumental for the development of modern plant molecular biology and biotechnology. In this review, we provide extensive guidelines built on current synthetic biology advances that streamline infectious clone assembly, thus lessening a major technical constraint of plant virology. The focus is on generation of infectious clones in binary T-DNA vectors, which are delivered efficiently to plants by Agrobacterium. We then summarize recent applications of plant viruses and explore emerging trends in microbiology, bacterial and human virology that, once translated to plant virology, could lead to the development of virus-based gene therapies for ad hoc engineering of plant traits. The systematic characterization of plant virus roles in the phytobiome and next-generation virus-based tools will be indispensable landmarks in the synthetic biology roadmap to better crops.

Plant virus-based materials for biomedical applications: Trends and prospects

Nanomaterials composed of plant viral components are finding their way into medical technology and health care, as they offer singular properties. Precisely shaped, tailored virus nanoparticles (VNPs) with multivalent protein surfaces are efficiently loaded with functional compounds such as contrast agents and drugs, and serve as carrier templates and targeting vehicles displaying e.g. peptides and synthetic molecules. Multiple modifications enable uses including vaccination, biosensing, tissue engineering, intravital delivery and theranostics. Novel concepts exploit self-organization capacities of viral building blocks into hierarchical 2D and 3D structures, and their conversion into biocompatible, biodegradable units. High yields of VNPs and proteins can be harvested from plants after a few days so that various products have reached or are close to commercialization. The article delineates potentials and limitations of biomedical plant VNP uses, integrating perspectives of chemistry, biomaterials sciences, molecular plant virology and process engineering.

Suppressing a plant-parasitic nematode with fungivorous behavior by fungal transformation of a Bt cry gene

BACKGROUND

Pine wilt disease, caused by the pinewood nematode Bursaphelenchus xylophilus (PWN), is an important destructive disease of pine forests worldwide. In addition to behaving as a plant-parasitic nematode that feeds on epithelial cells of pines, this pest relies on fungal associates for completing its life cycle inside pine trees. Manipulating microbial symbionts to block pest transmission has exhibited an exciting prospect in recent years; however, transforming the fungal mutualists to toxin delivery agents for suppressing PWN growth has received little attention.

RESULTS

In the present study, a nematicidal gene cry5Ba3, originally from a soil Bacillus thuringiensis (Bt) strain, was codon-preferred as cry5Ba3Φ and integrated into the genome of a fungus eaten by PWN, Botrytis cinerea, using Agrobacterium tumefaciens-mediated transformation. Supplementing wild-type B. cinerea extract with that from the cry5Ba3Φ transformant significantly suppressed PWN growth; moreover, the nematodes lost fitness significantly when feeding on the mycelia of the cry5Ba3Φ transformant. N-terminal deletion of Cry5Ba3Φ protein weakened the nematicidal activity more dramatically than did the C-terminal deletion, indicating that domain I (endotoxin-N) plays a more important role in its nematicidal function than domain III (endotoxin-C), which is similar to certain insecticidal Cry proteins.

CONCLUSIONS

Transformation of Bt nematicidal cry genes in fungi can alter the fungivorous performance of B. xylophilus and reduce nematode fitness. This finding provides a new prospect of developing strategies for breaking the life cycle of this pest in pines and controlling pine wilt disease.

Spherical and Spindle-Like Abamectin-Loaded Nanoparticles by Flash Nanoprecipitation for Southern Root-Knot Nematode Control: Preparation and Characterization

Southern root-knot nematode (Meloidogyne incognita) is a biotrophic parasite, causing enormous loss in global crop production annually. Abamectin (Abm) is a biological and high-efficiency pesticide against Meloidogyne incognita. In this study, a powerful method, flash nanoprecipitation (FNP), was adopted to successfully produce Abm-loaded nanoparticle suspensions with high drug loading capacity (>40%) and encapsulation efficiency (>95%), where amphiphilic block copolymers (BCPs) poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG), poly(d,l-lactide)-b-poly(ethylene glycol) (PLA-b-PEG), or poly(caprolactone)-b-poly(ethylene glycol) (PCL-b-PEG) were used as the stabilizer to prevent the nanoparticles from aggregation. The effect of the drug-to-stabilizer feed ratio on the particle stability were investigated. Moreover, the effect of the BCP composition on the morphology of Abm-loaded nanoparticles for controlling Meloidogyne incognita were discussed. Notably, spindle-like nanoparticles were obtained with PCL-b-PEG as the stabilizer and found significantly more efficient (98.4% mortality at 1 ppm particle concentration) than spherical nanoparticles using PLGA-b-PEG or PLA-b-PEG as the stabilizer. This work provides a more rapid and powerful method to prepare stable Abm-loaded nanoparticles with tunable morphologies and improved effectiveness for controlling Meloidogyne incognita.

Characterization and evaluation of avermectin solid nanodispersion prepared by microprecipitation and lyophilisation techniques

Poorly water-soluble and photosensitive pesticide compounds are difficult to formulate as solvent-free nanoformulations with high efficacy. A avermectin solid nanodispersion with a mean particle size of 188 nm was developed by microprecipitation and lyophilisation techniques. The suspensibility and wetting time of the solid nanodispersion in water were 99.8% and 13 s, respectively, superior to those of conventional water dispersible granules and wettable powders. The anti-photolysis performance of the nanoformulation was twice that of the technical material, and the biological activity against diamondback moths was more than 1.5 times that of the conventional solid formulations while taking LC 50 as the evaluation index. Moreover, the formulation composition substantially decreased the surfactant content and avoided organic solvents. Microprecipitation combined with lyophilisation is an easy and promising method to construct solid nanoformulations for pesticides with poor water solubility and environmental sensitivity. The application of the highly effective solid nanodispersion in crop production will have a great potential in reducing chemical residues and environmental pollution.

Plant Virus-Based Nanoparticles for the Delivery of Agronomic Compounds as a Suspension Concentrate

Nanoparticle formulations of agrichemicals may enhance their performance while simultaneously mitigating any adverse environmental effects. Red clover necrotic mosaic virus (RCNMV) is a soil-transmitted plant virus with many inherent attributes that allow it to function as a plant virus-based nanoparticle (PVN) when loaded with biologically active ingredients. Here we describe how to formulate a PVN loaded with the nematicide abamectin (Abm) beginning with the propagation of the virus through the formulation, deactivation, and characterization of the finished product.

Coherent anti-Stokes Raman scattering (CARS) spectroscopy in Caenorhabditis elegans and Globodera pallida: evidence for an ivermectin-activated decrease in lipid stores

BACKGROUND

Macrocyclic lactones are arguably the most successful chemical class with efficacy against parasitic nematodes. Here we investigated the effect of the macrocyclic lactone ivermectin on lipid homeostasis in the plant parasitic nematode Globodera pallida and provide new insight into its mode of action.

RESULTS

A non-invasive, non-destructive, label-free and chemically selective technique called Coherent anti-Stokes Raman scattering (CARS) spectroscopy was used to study lipid stores in G. pallida. We optimised the protocol using the free-living nematode Caenorhabditis elegans and then used CARS to quantify lipid stores in the pre-parasitic, non-feeding J2 stage of G. pallida. This revealed a concentration of lipid stores in the posterior region of J2 s within 24 h of hatching which decreased to undetectable levels over the course of 28 days. We tested the effect of ivermectin on J2 viability and lipid stores. Within 24 h, ivermectin paralysed J2 s. Counterintuitively, over the same time-course ivermectin increased the rate of depletion of J2 lipid, suggesting that in ivermectin-treated J2 s there is a disconnection between the energy requirements for motility and metabolic rate. This decrease in lipid stores would be predicted to negatively impact on J2 infective potential.

CONCLUSION

These data suggest that the benefit of macrocyclic lactones as seed treatments may be underpinned by a multilevel effect involving both neuromuscular inhibition and acceleration of lipid metabolism. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Synthetic plant virology for nanobiotechnology and nanomedicine

Nanotechnology is a rapidly expanding field seeking to utilize nano-scale structures for a wide range of applications. Biologically derived nanostructures, such as viruses and virus-like particles (VLPs), provide excellent platforms for functionalization due to their physical and chemical properties. Plant viruses, and VLPs derived from them, have been used extensively in biotechnology. They have been characterized in detail over several decades and have desirable properties including high yields, robustness, and ease of purification. Through modifications to viral surfaces, either interior or exterior, plant-virus-derived nanoparticles have been shown to support a range of functions of potential interest to medicine and nano-technology. In this review we highlight recent and influential achievements in the use of plant virus particles as vehicles for diverse functions: from delivery of anticancer compounds, to targeted bioimaging, vaccine production to nanowire formation. WIREs Nanomed Nanobiotechnol 2017, 9:e1447. doi: 10.1002/wnan.1447 For further resources related to this article, please visit the WIREs website.

Delivery of Pesticides to Plant Parasitic Nematodes Using Tobacco Mild Green Mosaic Virus as a Nanocarrier

Plant parasitic nematodes are a major burden to the global agricultural industry, causing a $157 billion loss each year in crop production worldwide. Effective treatment requires large doses of nematicides to be applied, putting the environment and human health at risk. Challenges are to treat nematodes that are located deep within the soil, feeding on the roots of plants. To attack the problem at its roots, we propose the use of tobacco mild green mosaic virus (TMGMV), an EPA-approved herbicide as a carrier to deliver nematicides. TMGMV self-assembles into a 300 × 18 nm soft matter nanorod with a 4 nm-wide hollow channel. This plant virus is comprised of 2130 identical coat protein subunits, each of which displays solvent-exposed carboxylate groups from Glu/Asp as well as Tyr side chains, enabling the functionalization of the carrier with cargo. We report (1) the successful formulation and characterization of TMGMV loaded with ∼1500 copies of the anthelmintic drug crystal violet (CV), (2) the bioavailability and treatment efficacy of _CVTMGMV vs CV to nematodes in liquid cultures, and (3) the superior soil mobility of _CVTMGMV compared to free CV.

Plant viruses and bacteriophages for drug delivery in medicine and biotechnology

There are a wide variety of synthetic and naturally occurring nanomaterials under development for nanoscale cargo-delivery applications. Viruses play a special role in these developments, because they can be regarded as naturally occurring nanomaterials evolved to package and deliver cargos. While any nanomaterial has its advantage and disadvantages, viral nanoparticles (VNPs), in particular the ones derived from plant viruses and bacteriophages, are attractive options for cargo-delivery as they are biocompatible, biodegradable, and non-infectious to mammals. Their protein-based structures are often understood at atomic resolution and are amenable to modification with atomic-level precision through chemical and genetic engineering. Here we present a focused review of the emerging technology development of plant viruses and bacteriophages targeting human health and agricultural applications. Key target areas of development are their use in chemotherapy, photodynamic therapy, pesticide-delivery, gene therapy, vaccine carriers, and immunotherapy.

Enhanced intracellular uptake in vitro by glucose-functionalized nanopesticides

Nanopesticides have been increasingly used in agriculture. To improve the uptake of the target organisms for nanopesticides, we designed a dual-ligand nanopesticide based on gold nanoparticles (Au NPs) as a carrier.