The in vivo fates of plant viral nanoparticles camouflaged using self-proteins: overcoming immune recognition

Surface modification potentials of cell membrane-based materials for targeted therapies: a chemotherapy-focused review

Nanotechnology has significant potential for cancer management at all stages, including prevention, diagnosis and treatment. In therapeutic applications, nanoparticles (NPs) have biological stability, targeting and body-clearance issues. To overcome these difficulties, biomimetic or cell membrane-coating methods using immune cell membranes are advised. Macrophage or neutrophil cell membrane-coated NPs may impede cancer progression in malignant tissue. Immune cell surface proteins and their capacity to maintain activity after membrane extraction and NP coating determine NP functioning. Immune cell surface proteins may offer NPs higher cellular interactions, blood circulation, antigen recognition for targeting, progressive drug release and reduced in vivo toxicity. This article examines nano-based systems with immune cell membranes, their surface modification potential, and their application in cancer treatment.

Plant-derived nanoparticles and plant virus nanoparticles: Bioactivity, health management, and delivery potential

Natural plants have acquired an increasing attention in biomedical research. Recent studies have revealed that plant-derived nanoparticles (PDNPs), which are nano-sized membrane vesicles released by plants, are one of the important material bases for the health promotion of natural plants. A great deal of research in this field has focused on nanoparticles derived from fresh vegetables and fruits. Generally, PDNPs contain lipids, proteins, nucleic acids, and other active small molecules and exhibit unique biological regulatory activity and editability. Specifically, they have emerged as important mediators of intercellular communication, and thus, are potentially suitable for therapeutic purposes. In this review, PDNPs were extensively explored; by evaluating them systematically starting from the origin and isolation, toward their characteristics, including morphological compositions, biological functions, and delivery potentials, as well as distinguishing them from plant-derived exosomes and highlighting the limitations of the current research. Meanwhile, we elucidated the variations in PDNPs infected by pathogenic microorganisms and emphasized on the biological functions and characteristics of plant virus nanoparticles. After clarifying these problems, it is beneficial to further research on PDNPs in the future and develop their clinical application value.

Assembly of Protein Cages for Drug Delivery

Nanoparticles (NPs) have been widely used as target delivery vehicles for therapeutic goods; however, compared with inorganic and organic nanomaterials, protein nanomaterials have better biocompatibility and can self-assemble into highly ordered cage-like structures, which are more favorable for applications in targeted drug delivery. In this review, we concentrate on the typical protein cage nanoparticles drugs encapsulation processes, such as drug fusion expression, diffusion, electrostatic contact, covalent binding, and protein cage disassembly/recombination. The usage of protein cage nanoparticles in biomedicine is also briefly discussed. These materials can be utilized to transport small molecules, peptides, siRNA, and other medications for anti-tumor, contrast, etc.

Multifunctional plant virus nanoparticles in the next generation of cancer immunotherapies

Plant virus nanoparticles (PVNPs) have inherent immune stimulatory ability, and have been investigated as immune adjuvants to stimulate an anti-tumor immune response. The combination of immune stimulation, nanoparticle structure and the ability to deliver other therapeutic molecules provides a flexible platform for cancer immunotherapy. Researching multifunctional PVNPs and their modification will generate novel reagents for cancer immunotherapy. Here we review the properties of PVNPs, and their potential for clinical utilization to activate anti-tumor innate and lymphoid immune responses. PVNPs have potential utility for cancer immunotherapy as vaccine adjuvant, and delivery systems for other reagents as mono immunotherapy or combined with other immunotherapies. This review outlines the potential and challenges in developing PVNPs as cancer immunotherapy reagents.

Photothermal immunotherapy of melanoma using TLR-7 agonist laden tobacco mosaic virus with polydopamine coat

Photothermal therapy (PTT) is a promising cancer treatment that debulks tumors locally while priming immune responses. However, PTT as a standalone treatment approach often has limited systemic efficacy, motivating the development of synergistic combination approaches. Toward this goal, herein, the tobacco mosaic virus (TMV) was loaded with a small molecule immunomodulator, toll-like receptor 7 agonist (1V209), and its surface was coated with photothermal biopolymer polydopamine (PDA). The resulting 1V209-laden and PDA-coated TMV was used to treat B16F10 dermal melanoma in C57BL/6 mice. 1V209-TMV-PDA was intratumorally injected and irradiated using an 808-nm near infrared laser. 60 % of the mice receiving PTT with intratumoral 1V209-TMV-PDA + laser remained alive at the end point - in contrast to only 20 % survivors were observed in the control group. Immunological analysis indicates systemic anti-tumor immunity being induced by the combination therapy with a greater number of tumor-specific T cells (as determined by a splenocyte assay). This study highlights the potential of TMV versatility as a multifunctional nano-platform for combined PTT-immunotherapy.

Chemical and Biophysical Signatures of the Protein Corona in Nanomedicine

An inconvenient hurdle in the practice of nanomedicine is the protein corona, a spontaneous collection of biomolecular species by nanoparticles in living systems. The protein corona is dynamic in composition and may entail improved water suspendability and compromised delivery and targeting to the nanoparticles. How much of this nonspecific protein ensemble is determined by the chemistry of the nanoparticle core and its surface functionalization, and how much of this entity is dictated by the biological environments that vary spatiotemporally in vivo? How do we "live with" and exploit the protein corona without significantly sacrificing the efficacy of nanomedicines in diagnosing and curing human diseases? This article discusses the chemical and biophysical signatures of the protein corona and ponders challenges ahead for the field of nanomedicine.

Quantitative Analysis of Protein Corona on Precoated Protein Nanoparticles and Determined Nanoparticles with Ultralow Protein Corona and Efficient Targeting in Vivo

The protein corona on nanoparticles (NPs) is a critical problem that often screens the targeting molecules and becomes one of the key reasons for the lack of practical application in nanotherapy. It is critical to fully understand the mechanism of the nanoparticle-biological interactions to design the nanoparticle-based therapeutic agents. Some types of proteins can be precoated on the nanoparticles to avoid unwanted protein attachment; however, the ultralow level of protein corona is hard to achieve, and the relationship of the antifouling property of the precoated protein nanoparticles with protein conformation and protein-nanoparticle interaction energy has never been investigated. In this work, we provided the quantitative protein corona composition analysis on different precoated protein nanoparticles, and on the basis of the molecular simulation process, we found their antifouling property strongly depended on the interaction energy of the precoated protein-serum protein pair and the number of hydrogen bonds formed between them. Furthermore, it also depended on the nanoparticle-serum protein pair interaction energy and the protein conformation on the nanoparticle. The casein coated nanoparticle with the antifouling property was determined, and after aptamer conjugation and drug loading, they exhibited superior targeting and internalization behavior for photodynamic and photothermal therapy in vitro and in vivo. Our work adds to the understanding of the protein corona behavior of precoated protein nanoparticles, and the determined antifouling NP can potentially be used as a highly efficient nanodrug carrier.

The in vivo fate of tobacco mosaic virus nanoparticle theranostic agents modified by the addition of a polydopamine coat

Plant virus nanoparticles (VNPs) have multiple advantages over their synthetic counterparts including the cost-effective large-scale manufacturing of uniform particles that are easy to functionalize. Tobacco mosaic virus (TMV) is one of the most promising VNP scaffolds, reflecting its high aspect ratio and ability to carry and/or display multivalent therapeutic ligands and contrast agents. Here we investigated the circulation, protein corona, immunogenicity, and organ distribution/clearance of TMV particles internally co-labeled with cyanine 5 (Cy5) and chelated gadolinium (Gd) for dual tracking by fluorescence imaging and optical emission spectrometry, with or without an external coating of polydopamine (PDA) to confer photothermal and photoacoustic capabilities. The PDA-coated particles (Gd-Cy5-TMV-PDA) showed a shorter plasma circulation time and broader distribution to organs of the reticuloendothelial system (liver, lungs, and spleen) than uncoated Gd-Cy5-TMV particles (liver and spleen only). The Gd-Cy5-TMV-PDA particles were surrounded by 2-10-fold greater protein corona (containing mainly immunoglobulins) compared to Gd-Cy5-TMV particles. However, the enzyme-linked immunosorbent assay (ELISA) revealed that PDA-coated particles bind 2-fold lesser to anti-TMV antibodies elicited by particle injection than uncoated particles, suggesting that the PDA coat enables evasion from systemic antibody surveillance. Gd-Cy5-TMV-PDA particles were cleared from organs after 8 days compared to 5 days for the uncoated particles. The slower tissue clearance of the coated particles makes them ideal for theranostic applications by facilitating sustained local delivery in addition to multimodal imaging and photothermal capabilities. We have demonstrated the potential of PDA-coated proteinaceous nanoparticles for multiple biomedical applications.

Extremely short bioavailability and fast pharmacodynamic effects of pMHC-based nanomedicines

Nanoparticles (NPs) coated with autoimmune disease-relevant peptide-major histocompatibility complexes (pMHCs) can blunt autoimmune diseases by re-programming cognate effector T-lymphocytes into disease-suppressing regulatory T-cells, followed by massive expansion. Here, a method to quantify the absolute amounts of the active drug product is developed, to understand the relationship between bioavailability and pharmacodynamics. Incubation with plasma results in the formation of a protein corona that stabilizes the directional pMHC coat, shielding it from proteolysis or anti-drug antibody recognition, without any appreciable loss in biological potency. A quantitative method that harnesses these features indicates that the half-life of these compounds in the circulation and organs is an order of magnitude shorter (minutes vs. hours) than that measured using commonly-used semi-quantitative methods. Extensive transmission electron microscopy-based organ scanning and flow cytometry-based enumeration of pMHCII-NP capturing cells confirmed that these compounds are rapidly captured (within 1 min) by liver sinusoidal endothelial cells, Kupffer cells, splenic phagocytes and cognate T-cells, leading to a fast decline in the circulation. Therefore, the powerful pharmacodynamic effects of these compounds are dissociated from long bioavailability, implying a hit-and-run event. Collectively, these data provide a detailed view of the life-cycle of a nanoimmunomedicine, and suggest that the real half-lives of intact nanomedicines may be much shorter than those estimated using indirect approaches.

New generation of viral nanoparticles for targeted drug delivery in cancer therapy

Nanoscale engineering is one of the novel methods to cure multitudes of diseases, such as types of cancers, neurological disorders, and infectious illnesses. Viruses can play a vital role in nanoscale engineering due to their specific properties like minuscule size, high stability in different body conditions, and large-scale production. Viral-like particles (VLPs) as specific nanoscale scaffolds can encapsulate a wide range of cargos, including nucleic acids, proteins, peptides, and drugs. The Exterior portion of VLPs can be changed by genetical or chemical conjugation as well as targeting ligands or peptides. The aforementioned features of VLPs can be used in several applications, such as drug delivery, bioimaging, tissue engineering, vaccine production, and disease detection. This review article attempts to investigate appearance characteristics, modification strategies, and manufacturing methods of VLPs. Additionally, drug delivery to cancer cells as one of the VLPs applications along with different cellular uptake mechanisms of VLPs by cancer cells are chosen for investigation. This review also tries to gather most of the recent studies of drug delivery to cancer cells by VLPs.

The Fate of Nanoparticles In Vivo and the Strategy of Designing Stealth Nanoparticle for Drug Delivery

Nano-drug delivery systems (Nano-DDS) offer powerful advantages in drug delivery and targeted therapy for diseases. Compared to the traditional drug formulations, Nano-DDS can increase solubility, biocompatibility, and reduce off-targeted side effects of free drugs. However, they still have some disadvantages that pose a limitation in reaching their full potential in clinical use. Protein adsorption in blood, activation of the complement system, and subsequent sequestration by the mononuclear phagocyte system (MPS) consequently result in nanoparticles (NPs) to be rapidly cleared from circulation. Therefore, NPs have low drug delivery efficiency. So, it is important to develop stealth NPs for reducing bio-nano interaction. In this review, we first conclude the interaction between NPs and biological environments, such as blood proteins and MPS, and factors influencing each other. Next, we will summarize the new strategies to reduce NPs protein adsorption and uptake by the MPS based on current knowledge of the bio-nano interaction. Further directions will also be highlighted for the development of biomimetic stealth nano-delivery systems by combining targeted strategies for a better therapeutic effect.

The pharmacology of plant virus nanoparticles

The application of nanoparticles for medical purposes has made enormous strides in providing new solutions to health problems. The observation that plant virus-based nanoparticles (VNPs) can be repurposed and engineered as smart bio-vehicles for targeted drug delivery and imaging has launched extensive research for improving the therapeutic and diagnostic management of various diseases. There is evidence that VNPs are promising high value nanocarriers with potential for translational development. This is mainly due to their unique features, encompassing structural uniformity, ease of manufacture and functionalization by means of expression, chemical biology and self-assembly. While the development pipeline is moving rapidly, with many reports focusing on engineering and manufacturing aspects to tailor the properties and efficacy of VNPs, fewer studies have focused on gaining insights into the nanotoxicity of this novel platform nanotechnology. Herein, we discuss the pharmacology of VNPs as a function of formulation and route of administration. VNPs are reviewed in the context of their application as therapeutic adjuvants or nanocarrier excipients to initiate, enhance, attenuate or impede the formulation's toxicity. The summary of the data however also underlines the need for meticulous VNP structure-nanotoxicity studies to improve our understanding of their in vivo fates and pharmacological profiles to pave the way for translation of VNP-based formulations into the clinical setting.

Stabilized albumin coatings on engineered xenografts for attenuation of acute immune and inflammatory responses

Xenogeneic grafts are promising candidates for transplantation therapy due to their easily accessible sources. Nevertheless, the immune and inflammatory responses induced by xenografts need to be addressed for clinical use. A novel and facile method was introduced for the attenuation of immune and inflammatory responses by extending the immune evasion potential of albumin to the tissue engineering field and coating albumin, which could passivate biomaterial surfaces, onto xenografts. Albumin was first modified by dopamine to enhance its adhesion on graft surfaces. Porcine chondrocytes derived living hyaline cartilage graft (LhCG) and decellularized LhCG (dLhCG) were applied as xenograft models implanted in the omentum of rats. Both LhCG which contained porcine chondrocytes as well as secreted ECM and dLhCG which was mainly composed of the porcine source ECM showed alleviated immune and inflammatory responses after being coated with albumin at cell, protein and gene levels, respectively. Significantly less inflammatory cells including neutrophils, macrophages and lymphocytes were recruited according to pathological analysis and immunohistochemistry staining with lower gene expression encoding inflammation-related cytokines including MCP-1, IL-6 and IL-1β after employing LhCG and dLhCG with albumin passivation coating.

Knowledge gaps in immune response and immunotherapy involving nanomaterials: Databases and artificial intelligence for material design

Exploring the interactions between the immune system and nanomaterials (NMs) is critical for designing effective and safe NMs, but large knowledge gaps remain to be filled prior to clinical applications (e.g., immunotherapy). The lack of databases on interactions between the immune system and NMs affects the discovery of new NMs for immunotherapy. Complement activation and inhibition by NMs have been widely studied, but the general rules remain unclear. Biomimetic nanocoating to promote the clearance of NMs by the immune system is an alternative strategy for the immune response mediation of the biological corona. Immune response predictions based on NM properties can facilitate the design of NMs for immunotherapy, and artificial intelligences deserve much attention in the field. This review addresses the knowledge gaps regarding immune response and immunotherapy in relation to NMs, effective immunotherapy and material design without adverse immune responses.

Recent Advances in Understanding the Protein Corona of Nanoparticles and in the Formulation of "Stealthy" Nanomaterials

In the last decades, the staggering progress in nanotechnology brought around a wide and heterogeneous range of nanoparticle-based platforms for the diagnosis and treatment of many diseases. Most of these systems are designed to be administered intravenously. This administration route allows the nanoparticles (NPs) to widely distribute in the body and reach deep organs without invasive techniques. When these nanovectors encounter the biological environment of systemic circulation, a dynamic interplay occurs between the circulating proteins and the NPs, themselves. The set of proteins that bind to the NP surface is referred to as the protein corona (PC). PC has a critical role in making the particles easily recognized by the innate immune system, causing their quick clearance by phagocytic cells located in organs such as the lungs, liver, and spleen. For the same reason, PC defines the immunogenicity of NPs by priming the immune response to them and, ultimately, their immunological toxicity. Furthermore, the protein corona can cause the physical destabilization and agglomeration of particles. These problems induced to consider the PC only as a biological barrier to overcome in order to achieve efficient NP-based targeting. This review will discuss the latest advances in the characterization of PC, development of stealthy NP formulations, as well as the manipulation and employment of PC as an alternative resource for prolonging NP half-life, as well as its use in diagnostic applications.

Self-Albumin Camouflage of Carrier Protein Prevents Nontarget Antibody Production for Enhanced LDL-C Immunotherapy

Elevated low-density lipoprotein cholesterol (LDL-C) increases the risk of atherosclerotic cardiovascular disease. Peptide-based PCSK9 vaccines have shown a promising prospect of reducing LDL-C. In peptide vaccine (pVax) design, the peptide antigens need to conjugate with carrier protein (CP). However, CP incorporation can induce undesirable anti-CP antibodies, which sterically mask peptide epitopes from being recognized by specific B cells and impair subsequent therapeutically antibody production. This epitopic suppression has posed a barrier in clinical translation of conjugate vaccines all along. A model CP (keyhole limpet hemocyanin, KLH) is herein camouflaged with serum albumin (SA) into hybrid nanocarriers (SA@N), with PCSK9 peptide being anchored onto the surface to form nanovaccine (SA@NVax). Such camouflage of KLH via high "self" SA coverage is able to inhibit KLH from extracellular immune recognition and prevent detectable anti-KLH antibody production. Furthermore, the nanovaccine around 70 nm stabilized by intermolecular disulfide network is ideal for internalization and biodegradation by antigen presenting cells as well as better retention in draining lymph nodes and spleen. As expected, the SA@NVax efficiently primes higher anti-PCSK9 IgG antibody titer than PCSK9 pVax.

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.

Developing Protein-Based Nanoparticles as Versatile Delivery Systems for Cancer Therapy and Imaging

In recent years, it has become apparent that cancer nanomedicine's reliance on synthetic nanoparticles as drug delivery systems has resulted in limited clinical outcomes. This is mostly due to a poor understanding of their "bio-nano" interactions. Protein-based nanoparticles (PNPs) are rapidly emerging as versatile vehicles for the delivery of therapeutic and diagnostic agents, offering a potential alternative to synthetic nanoparticles. PNPs are abundant in nature, genetically and chemically modifiable, monodisperse, biocompatible, and biodegradable. To harness their full clinical potential, it is important for PNPs to be accurately designed and engineered. In this review, we outline the recent advancements and applications of PNPs in cancer nanomedicine. We also discuss the future directions for PNP research and what challenges must be overcome to ensure their translation into the clinic.

Delivery of siRNA therapeutics using cowpea chlorotic mottle virus-like particles

While highly promising in medicine, gene therapy requires delivery agents to protect and target nucleic acid therapeutics. We developed a plant viral siRNA delivery platform making use of self-assembling cowpea chlorotic mottle virus (CCMV). CCMV was loaded with siRNAs targeting GFP or FOXA1; to further enhance cell uptake and intracellular trafficking, resulting in more efficient gene knockdown, we appended CCMV with a cell penetrating peptide (CPP), specifically M-lycotoxin peptide L17E.

Future of cancer immunotherapy using plant virus-based nanoparticles

Immunotherapy potentiates a patient’s immune response against some forms of cancer, including malignant tumors. In this Special Report, we have summarized the use of nanoparticles that have been designed for use in cancer immunotherapy with particular emphasis on plant viruses. Plant virus-based nanoparticles are an ideal choice for therapeutic applications, as these nanoparticles are not only capable of targeting the desired cells but also of being safely delivered to the body without posing any threat of infection. Plant viruses can be taken up by tumor cells and can be functionalized as drug delivery vehicles. This Special Report describes how the future of cancer immunotherapy could be a success through the merger of computer-based technology using plant-virus nanoparticles.

The nonpathogenic nature of plant viral nanoparticles makes them an ideal choice for therapeutic applications such as cancer. Understanding the molecular mechanisms behind the immune response to cancer has facilitated the use of nanotechnology as an effective cancer therapy. Biologically active self-replicating plant virus particles can be introduced to the bloodstream of the human body and used as effective drug delivery vehicles. This Special Report describes how a combination of computer-based technology and plant-virus nanoparticles can assist in cancer immunotherapy.

Polydopamine-decorated tobacco mosaic virus for photoacoustic/magnetic resonance bimodal imaging and photothermal cancer therapy

Nanotheranostic reagents that integrate magnetic resonance imaging (MRI) and photothermal therapy (PTT) offer a promising strategy for the treatment of human disease. However, classic gadolinium (Gd)-based T1-MRI contrast agents are limited by their low relaxivity. To address this, we produced Gd-loaded Tobacco mosaic virus (TMV) particles coated with the mussel-inspired biopolymer polydopamine (PDA). Such biocompatible nanotheranostic reagents can be used to facilitate PTT, guided by multimodal magnetic resonance/photoacoustic imaging. The r1-relaxivity of the Gd-TMV-PDA particles at 60 MHz was ∼80 mM-1 s-1, compared to 13.63 mM-1 s-1 for the uncoated Gd-TMV particles. The Gd-TMV-PDA particles also promoted strong near-infrared absorption with high photothermal conversion efficiency (28.9%) and demonstrated excellent photoacoustic contrast. Multimodal imaging and PTT resulted in the effective killing of PC-3 prostate cancer cells. Gd-TMV-PDA nanoparticles therefore offer a promising theranostic approach that can now be tested in vivo in cancer models.

Presentation and Delivery of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand via Elongated Plant Viral Nanoparticle Enhances Antitumor Efficacy

Potato virus X (PVX) is a flexuous plant virus-based nanotechnology with promise in cancer therapy. As a high aspect ratio biologic (13 × 515 nm), PVX has excellent spatial control in structures and functions, offering high-precision nanoengineering for multivalent display of functional moieties. Herein, we demonstrate the preparation of the PVX-based nanocarrier for delivery of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a promising protein drug that induces apoptosis in cancer cells but not healthy cells. TRAIL bound to PVX by coordination bonds between nickel-coordinated nitrilotriacetic acid on PVX and His-tag on the protein could mimic the bioactive "membrane-bound" state in native TRAIL, resulting in an elongated nanoparticle displaying up 490 therapeutic protein molecules. Our data show that PVX-delivered TRAIL activates caspase-mediated apoptosis more efficiently compared to soluble TRAIL; also in vivo the therapeutic nanoparticle outperforms in delaying tumor growth in an athymic nude mouse model bearing human triple-negative breast cancer xenografts. This proof-of-concept work highlights the potential of filamentous plant virus nanotechnologies, particularly for targeting protein drug delivery for cancer therapy.

Development of improved dual-diazonium reagents for faster crosslinking of tobacco mosaic virus to form hydrogels

New bench-stable reagents with two diazonium sites were designed and synthesized for protein crosslinking. Because of the faster diazonium-tyrosine coupling reaction, hydrogels from the crosslinking of tobacco mosaic virus and the reagent DDA-3 could be prepared within 1 min at room temperature. Furthermore, hydrogels with the introduction of disulfide bonds viaDDA-4 could be chemically degraded by dithiothreitol. Our results provided a facile approach for the direct construction of virus-based hydrogels.

Improved dual-diazonium reagents were developed for more efficient crosslinking of tobacco mosaic virus to form hydrogels.

Cancer Theranostic Applications of Albumin-Coated Tobacco Mosaic Virus Nanoparticles

Nanotechnology holds great promise in cancer drug delivery, and of particular interest are theranostic approaches in which drug delivery and imaging are integrated. In this work, we studied and developed the plant virus tobacco mosaic virus (TMV) as a platform nanotechnology for drug delivery and imaging. Specifically, a serum albumin (SA)-coated TMV formulation was produced. The SA coating fulfils two functions: SA provides a stealth coating for enhanced biocompatibility; it also acts as a targeting ligand enabling efficient tumor accumulation of SA-TMV versus TMV in mouse models of breast and prostate cancer. We demonstrate drug delivery of the chemotherapy doxorubicin (DOX); TMV-delivered DOX outperformed free DOX, resulting in significant delayed tumor growth and increased survival. Furthermore, we demonstrated the ability of SA-coated TMV loaded with chelated Gd(DOTA) for magnetic resonance imaging detection of tumors. In the future, we envision the application of such probes as theranostic, where first imaging is performed to assess whether the nanoparticles are effective at targeting a particular patient tumor. If targeting is confirmed, the therapeutic would be added and treatment can begin. The combination of imaging and therapy would allow to monitor disease progression and therefore inform about the effectiveness of the drug delivery approach.

Albumin conjugates and assemblies as versatile bio-functional additives and carriers for biomedical applications

As the most abundant plasma protein, serum albumin has been extensively studied and employed for therapeutic applications. Despite its direct clinical use for the maintenance of blood homeostasis in various medical conditions, this review exclusively summarizes and discusses albumin-based bio-conjugates and assemblies as versatile bio-functional additives and carriers in biomedical applications. As one of the smallest-sized proteins in the human body, albumin is physiochemically stable and biochemically inert. Moreover, albumin is also endowed with abundant specific binding sites for numerous therapeutic compounds, which also endow it with superior bioactivities. Firstly, due to its small size and binding specificity, albumin alone or its derived assemblies can be utilized as competent drug carriers, which can deliver drugs through the enhanced permeability and retention (EPR) effect or actively target lesion sites through binding with gp60 and secreted protein acidic and rich in cysteine (SPARC) in tumor sites. Furthermore, its biochemical stability and inertness make it a safe and biocompatible coating material for use in biomedical applications. Albumin-based surface modifying additives can be used to functionalize both macro substrates (e.g. surfaces of medical devices or implants) and nanoparticle surfaces (e.g. drug carriers and imaging contrast agents). In this review, we elaborate on the synthesis and applications of albumin-based bio-functional coatings and drug carriers, respectively.

Delivery of thrombolytic therapy using rod-shaped plant viral nanoparticles decreases the risk of hemorrhage

Cardiovascular thrombotic disease is an underlying cause of stroke, myocardial infarction and pulmonary embolism - some of the leading causes of death worldwide. Reperfusion therapy with anticoagulant, antiplatelet, and fibrinolytic agents has significantly reduced early mortality and morbidity from acute myocardial infarction and stroke. Nevertheless, bleeding side effects (e.g., intracranial hemorrhage) associated with the anti-thrombotic therapy can offset its benefits and limit its applicability to strictly defined short therapeutic windows. We have previously shown that elongated plant virus based nanoparticles can target cardiovascular thrombi and exhibited their utility for the delivery of streptokinase in an ex vivo model of thrombosis. Herein, we build upon our previous findings and demonstrate plant viral delivery of the current standard-of-care tissue plasminogen activator (tPA). Studies on a pre-clinical mouse model of arterial thrombosis indicate that while the therapeutic efficacy of free tPA and tPA-conjugated TMV are similar, the safety profile of the tPA-TMV formulation is improved, i.e. administration of the latter has less impact on hemostasis as demonstrated by decreased bleeding time. Thus, our data suggest that TMV-based delivery of thrombolytic therapies could be a promising and safer alternative to reperfusion therapy with the tPA.

Bioinspired Shielding Strategies for Nanoparticle Drug Delivery Applications

Nanoparticle delivery systems offer advantages over free drugs, in that they increase solubility and biocompatibility. Nanoparticles can deliver a high payload of therapeutic molecules while limiting off-target side effects. Therefore, delivery of an existing drug with a nanoparticle frequently results in an increased therapeutic index. Whether of synthetic or biologic origin, nanoparticle surface coatings are often required to reduce immune clearance and thereby increase circulation times allowing the carriers to reach their target site. To this end, polyethylene glycol (PEG) has long been used, with several PEGylated products reaching clinical use. Unfortunately, the growing use of PEG in consumer products has led to an increasing prevalence of PEG-specific antibodies in the human population, which in turn has fueled the search for alternative coating strategies. This review highlights alternative bioinspired nanoparticle shielding strategies, which may be more beneficial moving forward than PEG and other synthetic polymer coatings.