Each ferritin complex can sequester up to 4500 Fe2+ ions and convert them to Fe3+ to prevent oxidative stress in the cytosol, nucleus, and mitochondria. Ferritin has been investigated as an imaging reagent and vaccine platform as well as a nanocarrier.It has already been used to deliver cisplatin,doxorubicin,and curcumin,and the contrast agents gadolinium and Mn. There are few examples of proteinaceous nanocarriers used in agriculture, but nanocarriers based on maize storage proteins are being tested for the delivery of pesticides that protect soybean crops from defoliator parasites.The number of proteinaceous nanocarriers reaching the market will continue to grow as we learn more from nature and expand our bioengineering tools and processing capabilities, including the use of genome editing and directed evolution.Furthermore, rather than harnessing protein complexes from nature, advances in de novo protein design will allow us to select customized proteins with shapes that may be difficult to obtain via the directed evolution of natural proteins.Modular building concepts have been established to achieve the defined folding and programmed assembly of proteins into complex architectures.Accordingly, some synthetically designed protein-based nanoparticles have entered translational development. For example, the start-up company Tychon Bioscience is developing prosthetic antigen receptors that modulate protein dimerization to produce self-assembling nanoscale ring structures for applications in cancer immunotherapy. The entirety of my dissertation relied on the use of virus-based nanocarriers and their application in medicine and agriculture; they present many advantages over the other nanocarrier platforms,blueberry grow bag as described below and in all chapters of my dissertation. Viruses have evolved to deliver their genetic payload to host cells and can therefore be regarded as nature’s nanocarrier systems.
The structure of a virus capsid is genetically programmed so replication yields millions of identical particles, a level of monodispersity that cannot yet be achieved with synthetic nanoparticles. Viruses are proteinaceous structures, and are therefore similar to the protein cages discussed above in terms of biocompatibility. The capsids are highly symmetrical structures that come in various shapes and sizes, and they are amenable to both chemical and genetic modification to impart new functionalities, including the encapsulation or conjugation of active ingredients Given the natural function of viruses, it is unsurprising that one of the first applications of virus-based nanocarriers was the delivery of nucleic acids. Mammalian viruses such as Adenoassociated virus are established as gene delivery vectors.The first AAV-based gene therapy vector was approved by the EMA in 2012 for the treatment of lipoprotein lipase deficiency, but was not approved by the FDA, and UniQure subsequently announced its withdrawal from the European market in 2017 following the treatment of only 31 patients.The FDA has since approved two AAV-based vectors, namely Luxturna in 2017 for the treatment of patients with RPE65 mutation-associated retinal dystrophy, and Zolgensma in 2019 for the treatment of young infants with spinal muscular atrophy. One of the major drawbacks of AAV therapies is their high cost: Luxturna treatment is estimated to cost $850,000, whereas Zolgensma was priced at $2.125 million by Novartis as a one-time cure. In addition to AAV nanocarriers , other mammalian viruses have been developed for gene delivery including adenoviruses , herpesviruses , and lentiviruses and are undergoing clinical trials , whereas retroviruses and alphaviruses remain at the preclinical development stage.As an alternative to mammalian viruses, several plant viruses and bacteriophages have also been repurposed as nanocarriers or vaccines because they are non-infectious to humans and can be manufactured on a large scale as viral nanoparticles or virus-like particles .
For example, based on the immunostimulatory nature of VNPs/VLPs, several have been developed as in situ cancer vaccines, including Cowpea mosaic virus bacteriophage M13,Potato virus X ,Tobacco mosaic virus ,and Papaya mosaic virus.The CPMV system has already demonstrated efficacy in canine trials.The development of plant viruses or bacteriophages as vaccine candidates for infectious diseases, autoimmune disorders and cancer has been extensively reviewed.One of the key applications of VNP/VLP vaccine candidates is the display of heterologous epitopes.This protects the epitope from degradation, ensures delivery to antigen-presenting cells, provides an inbuilt adjuvant, and also generates cross stimulatory virus-based antigens to boost humoral and cellular immunity.Several VNPs/VLPs presenting heterologous epitopes have been tested in human clinical trials and veterinary tests.The use of VNPs and VLPs as nanocarriers for active ingredients can be achieved by passive infusion through pores in the capsid, encapsulation during assembly, as well as chemical conjugation and/or genetic fusion of active ingredients to the outer or inner surfaces. For example, doxorubicin has been conjugated to TMV,infused into Cucumber mosaic virus and Red clover necrotic mosaic virus ,and passively complexed with PVX.Virusbased nanocarriers have also been used to deliver bortezomib,cisplatin,5-fluorouracil,hygromycin,mitoxantrone,phenanthriplatin,and paclitaxel.Examples of protein delivery include TRAIL,40 TPA,and Herceptin. Filamentous phages have been developed to deliver antibiotics such as chloramphenicol and neomycin to prevent the growth of Escherichia coli, Streptococcus pyogenes, and Staphylococcus aureus.Finally, siRNA has been delivered using bacteriophage MS2 and Cowpea chlorotic mosaic virus ,and mRNA for the in situ expression of green fluorescent protein has been successfully encapsulated into CCMV and TMV, followed by the release of the mRNA cargo into the cytosol of mammalian cells and its subsequent translation.Plant VNPs have also been proposed as pesticide carriers because they are already part of the natural soil ecosystem and are harmless to humans and domestic animals.
Compared to synthetic nanocarriers, plant viruses are highly mobile in soil and can deliver pesticides to the roots, where many pests are concentrated. TMGMV was approved by the EPA in 2007 as a bioherbicide for the treatment of the invasive tropical soda apple weed in the state of Florida, thus paving the way for the development of nanocarriers based on plant viruses.Since then, RCNMV has been proposed for the delivery of abamectin to crops.The higher stability and superior soil mobility of abamectin encapsulated in RCNMV increased the efficacy of the nematicide in tomato seedlings infested with root knot nematodes compared to the free chemical. Similarly, TMGMV loaded with the anthelmintic drug crystal violet was highly toxic towards the nematode Caenorhabditis elegans in vitro. Rational design and size and shape engineering in plant virus-based carriers may enable multi-level targeting of different soil zones.Nanocarriers have revolutionized the medical, veterinary, and agricultural sectors through their ability to deliver active ingredients in a targeted and controlled manner to appropriate sites, such as cancer cells or plant roots, thereby maximizing efficacy while minimizing off-target effects. Based on the current landscape of research articles, patents, clinical trials, and approved nanocarriers, I have revealed a growth trend which predicts that more formulations will be commercially available over time, allowing the targeted delivery of small molecules, peptides and proteins, as well as nucleic acids to combat pests, pathogens and diseases in animals and plants. I observed a shift away from the development of nanocarriers for small-molecule reagents and toward the delivery of peptides, proteins and nucleic acids. Advances in bioengineering have also encouraged the development of bio-inspired nanocarriers that are friendly to the environment. Several challenges must be addressed to streamline the translation of nanocarriers from the bench to the market. In medicine, nanocarriers could greatly benefit from the incorporation of targeting ligands, aptamers, antibodies, or antibody fragments to promote their binding to receptors overexpressed on target cells or in the surrounding extracellular matrix. Additional targeted nanocarriers must undergo clinical trials before we can conclude that active targeting achieves greater therapeutic efficacy. In parallel,blueberry grow bag size the development of veterinary nanocarriers has intensified with the growing public interest in animal welfare and food safety and security. Companion animals with cancer have benefited the most from nanocarriers, whereas livestock require low-cost and prolonged treatments, such as the delivery of antibiotics. The future of veterinary nanocarriers will depend on our ability to manufacture products at a relatively low cost. Finally, precision agriculture is required to meet the growing demand for food. Nanocarriers provide the opportunity to increase crop yields in an environmentally friendly manner by delivering fertilizers and pesticides directly to plants while minimizing leaching. However, the translation of nanocarriers for agricultural applications is restricted by the lack of well-structured regulations for commercial approval. More research is therefore required to determine the fate and toxicity of nanocarriers applied in the field.Plant parasites are a major burden to the global agricultural industry.
Among them, the United States Department of Agriculture has highlighted several species of insects and worms as the most common and devastating parasites; they either directly injure crops by feeding on them or indirectly cause injury through the transmission of bacteria, viruses, and fungi. Specifically, crops infested by parasitic worms, including across the United States, results in an estimated $157 billion loss each year in crop production worldwide.In particular, endoparasitic plant nematodes feed on the crop roots, causing distinctive root swellings commonly referred to as galls. Gall formation impairs the root conduction of water and growth nutrients into the rest of the plant, resulting in lower crop yields. In addition, galls often promote crack damages in the roots and increase the plant vulnerability to secondary infections.The root-knot Meloidogyne spp, the potato cyst Globodera spp, and the soybean cyst Heterodera glycines are the most damaging and widely spread plant parasitic nematodes. Combined they can infect more than 3000 plant species, including bananas, corn, cotton, potatoes, lettuce, and tomatoes.While crop nematode infestation is relatively easy to diagnose , treatment options are limited. In most countries, crop rotation is frequently employed to selectively control plant parasitic nematode infestations.Nonetheless, the wide host-range of root-knot nematodes limits the choice of alternate crops to a few species yielding little to no revenue. Genetically modified crops resistant to nematodes are an economically and environmentally viable alternative.Unfortunately, genetic resistance to plant parasitic nematodes is selective to specific nematode species, limited to a few crops, and takes years to engineer.While these aforementioned control strategies can reduce the burden of plant parasitic nematodes on most crops, their efficacy and economic benefits are no match to the use of nematicides.The first generation of nematicides rely on highly toxic and volatile fumigants, such as methyl bromide, but their use has declined due to environmental and health concerns.Alternatively, non-fumigant nematicides, such as organophosphates, carbamates, and bio-nematicides, have been employed.Their efficacy, however, is limited by their ability to diffuse through soil, which is dependent on the amount of organic matter, moisture, and the soil structure . To be effective, non-fumigant nematicides must persist long enough and in concentrations equivalent to the nematode-lethal dose at the root level. Extended persistence in such doses increases the risk of chemical contamination of crops, soil, and groundwater. Therefore, there is a critical need to resolve soil mobility issues of nematicides to enhance their agrochemical efficacy, reduce their indiscriminate use, and ensure their safe application. To attack the problem at its roots, nanotechnology has led to the development of smart delivery systems that can be tailored to deliver pesticides in a controlled and targeted manner,similar to nanomedicine in humans.Nanomaterials used as carriers have advantages over commonly used pesticides, such as enhanced biodegradability, thermal stability, permeability, dispersibility, wettability, and stiffness.When pesticide-loaded nanoparticles are spread uniformly over the soil surface, their large surface areas increase their affinity to the target pest and reduce the dose of pesticide required to effectively eradicate the infestation.In addition, encapsulation of nematicides in nanoparticles protect the active compound from premature biodegradation and photolysis while isolating the toxic nature of the nematicide from the end-user. Liposomal formulations, as well as synthetic and natural polymer-based nanoparticle formulations have been employed as pesticide-delivery systems While synthetic nanomaterials overcome the various challenges associated with the use of nematicides, it still remains uncertain whether their high cost of manufacturing makes them economically viable.In this study, I turn toward using plant viral nanoparticles as an economically and environmentally viable alternative to synthetic nanoparticles. In addition, VNPs are exceptionally robust to the harsh environment of crop fields, yet they are biodegradable. From a human health perspective, VNPs are bio-compatible and non-infectious, making them safe to use on industrial crops. From an engineering perspective, VNPs are self-assembling systems that form highly symmetrical, monodisperse structures, amenable to both chemical and genetic modifications to impart new functionalities.Since plant viruses have naturally evolved to protect and efficiently deliver their payload , they can be regarded as naturally occurring nanocarriers. At first glance, applying VNPs onto crops might seem counterintuitive since their natural hosts for infections are plants. However, Cao et al. recently introduced the concept by utilizing the red clover necrotic mosaic virus to manage plant parasitic nematode infestation.