Surface Functionalization of Rod-Shaped Viral Particles for Biomedical Applications

Multilayered ordered arrays self-assembled from a mixed population of nanoparticles

An experimentally-informed coarse-grained model is presented to probe the self-assembly of multiple types of charged nanoparticles in a one-pot mixture in the presence of oppositely charged linkers across a broad range of nanoparticle charge and ionic strength of the solution. The model is applied to study the self-assembly of negatively-charged bacteriophage P22 virus-like particles (VLPs) of different types, with each type comprising VLPs of a distinct surface charge, in the presence of positively-charged polyamidoamine (PAMAM) generation-6 (G6) dendrimers. The model accurately captures the self-assembly of one-component systems, including the assembly states of the highest-charged P22 variant that were inaccessible with earlier models, revealing that P22 VLPs assemble into ordered arrays below a threshold ionic strength that increases with increasing variant charge, consistent with experiments. Molecular dynamics simulations of two, three, and four-component mixtures of P22 VLPs show that changing the ionic strength gradually over the range of well separated threshold ionic strengths via dialysis generates hierarchical assembly of ordered multilayered core-shell structures, with each layer comprising VLPs of a single variant type. A quick decrease in the ionic strength via rapid dilution leads to amorphous aggregates with a mixed composition of different variants. The mechanisms driving the VLPs into different macrostructures are explored by examining the bound and bridging dendrimers associated with the different types of VLPs. Simulation findings are consistent with experiments and establish salt dialysis as a simple and versatile strategy to engineer multilayered and ordered structures via a single-pot synthesis of multiple types of nanoscale building blocks.

The Role of Plant Virus-like Particles in Advanced Drug Delivery and Vaccine Development: Structural Attributes and Application Potential

Plant virus-like particles (pVLPs) present distinct research advantages, including cost-effective production and scalability through plant-based systems, making them a promising yet underutilized alternative to traditional VLPs. Human exposure to plant viruses through diet for millions of years supports their biocompatibility and safety, making them suitable for biomedical applications. This review offers a practical guide to selecting pVLPs based on critical design factors. It begins by examining how pVLP size and shape influence cellular interactions, such as uptake, biodistribution, and clearance, key for effective drug delivery and vaccine development. We also explore how surface charge affects VLP-cell interactions, impacting binding and internalization, and discuss the benefits of surface modifications to enhance targeting and stability. Additional considerations include host range and biosafety, ensuring safe, effective pVLP applications in clinical and environmental contexts. The scalability of pVLP production across different expression systems is also reviewed, noting challenges and opportunities in large-scale manufacturing. Concluding with future perspectives, the review highlights the innovation potential of pVLPs in vaccine development, targeted therapies, and diagnostics, positioning them as valuable tools in biotechnology and medicine. This guide provides a foundation for selecting optimal pVLPs across diverse applications.

Current Advances in Viral Nanoparticles for Biomedicine

Viral nanoparticles (VNPs) have emerged as crucial tools in the field of biomedicine. Leveraging their biological and physicochemical properties, VNPs exhibit significant advantages in the prevention, diagnosis, and treatment of human diseases. Through techniques such as chemical bioconjugation, infusion, genetic engineering, and encapsulation, these VNPs have been endowed with multifunctional capabilities, including the display of functional peptides or proteins, encapsulation of therapeutic drugs or inorganic particles, integration with imaging agents, and conjugation with bioactive molecules. This review provides an in-depth analysis of VNPs in biomedicine, elucidating their diverse types, distinctive features, production methods, and complex design principles behind multifunctional VNPs. It highlights recent innovative research and various applications, covering their roles in imaging, drug delivery, therapeutics, gene delivery, vaccines, immunotherapy, and tissue regeneration. Additionally, the review provides an assessment of their safety and biocompatibility and discusses challenges and future opportunities in the field, underscoring the vast potential and evolving nature of VNP research.

Advancements in Functional Nanomaterials Inspired by Viral Particles

Virus-like particles (VLPs) are nanostructures composed of one or more structural proteins, exhibiting stable and symmetrical structures. Their precise compositions and dimensions provide versatile opportunities for modifications, enhancing their functionality. Consequently, VLP-based nanomaterials have gained widespread adoption across diverse domains. This review focuses on three key aspects: the mechanisms of viral capsid protein self-assembly into VLPs, design methods for constructing multifunctional VLPs, and strategies for synthesizing multidimensional nanomaterials using VLPs. It provides a comprehensive overview of the advancements in virus-inspired functional nanomaterials, encompassing VLP assembly, functionalization, and the synthesis of multidimensional nanomaterials. Additionally, this review explores future directions, opportunities, and challenges in the field of VLP-based nanomaterials, aiming to shed light on potential advancements and prospects in this exciting area of research.

A Combination of Flexible Modified Plant Virus Nanoparticles Enables Additive Effects Resulting in Improved Osteogenesis

Plant virus nanoparticles (VNPs) genetically engineered to present osteogenic cues provide a promising method for biofunctionalizing hydrogels in bone tissue engineering. Flexible Potato virus X (PVX) nanoparticles substantially enhance the attachment and differentiation of human mesenchymal stem cells (hMSCs) by presenting the RGD motif, hydroxyapatite-binding peptide (HABP), or consecutive polyglutamates (E8) in a concentration-dependent manner. Therefore, it is hypothesized that Tobacco mosaic virus nanoparticles, which present 1.6 times more functional peptides than PVX, will meliorate such an impact. This study hypothesizes that cultivating hMSCs on a surface coated with a combination of two VNPs presenting peptides for either cell attachment or mineralization can achieve additionally enhancing effects on osteogenesis. Calcium minerals deposited by differentiating hMSCs increases two to threefold for this combination, while the Alkaline Phosphatase activity of hMSCs grown on the PVX-RGD/PVX-HABP-coated surface significantly surpasses any other VNP combination. Superior additive effects are observed for the first time by employing a combination of VNPs with varying functionalities. It is found that the flexible VNP geometry plays a more critical role than the concentration of functional peptides. In conclusion, various peptide-presenting plant VNPs exhibit an additive enhancing effect offering significant potential for effectively functionalizing cell-containing hydrogels in bone tissue engineering.

Intrinsic disorder in the dynamic evolution of structure, stability, and flexibility of potyviral VLP assemblies: A computational study

An all-atom Molecular Dynamics (MD) study was applied to three viral nanoparticles (VLPs) of Turnip mosaic virus (TuMV), a potyvirus: the particles genetically functionalized with two peptides, VIP (human vasoactive intestinal peptide) and VEGFR (peptide derived from the human receptor 3 of the vascular endothelial growth factor), and the non-functionalized VLP. Previous experimental results showed that VIP-VLP was the only construct of the three that was not viable. VLPs subjected to our MD study were modeled by four complete turns of the particle involving 35 subunits of the coat protein (CP). The MD simulations showed differences in structures and interaction energies associated to the crucial contribution of the disordered N-terminal arms of CP to the global stability of the particle. These differences suggested an overall stability greater in VEGFR-VLP and smaller in VIP-VLP as compared to the unfunctionalized VLP. Our novel MD study of potyviral VLPs revealed essential clues about structure and interactions of these assembled protein particles and suggests that the computational prediction of the viability of VLPs can be a valuable contribution in the field of viral nanobiotechnology.

Engineering and Bio/Nanotechnological Applications of Virus Particles

Virus particles (VPs) are naturally evolved nanomachines. Their outstanding molecular structures, physical and chemical properties, and biological activities make them potentially useful for many biomedical or technological applications. Natural VPs such as virions or capsids must, however, be modified by genetic and/or chemical engineering in order to become adequate for many specific uses. We present first a general overview of the methods used for obtaining virions and viral capsids, and of genetic and chemical engineering approaches to suitably modify VPs. In the second part of the chapter, we present an updated overview on current or developing applications of engineered VPs as tools, materials, reagents, or nanodevices in biomedicine, biotechnology, or nanotechnology.

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.

Engineering Alkaline-Stable Barley Stripe Mosaic Virus-Like Particles for Efficient Surface Modification

Viruses and virus-like particles are powerful templates for materials synthesis because of their capacity for precise protein engineering and diverse surface functionalization. We recently developed a recombinant bacterial expression system for the production of barley stripe mosaic virus-like particles (BSMV VLPs). However, the applicability of this biotemplate was limited by low stability in alkaline conditions and a lack of chemical handles for ligand attachment. Here, we identify and validate novel residues in the BSMV Caspar carboxylate clusters that mediate virion disassembly through repulsive interactions at high pH. Point mutations of these residues to create attractive interactions that increase rod length ~2 fold, with an average rod length of 91 nm under alkaline conditions. To enable diverse chemical surface functionalization, we also introduce reactive lysine residues at the C-terminus of BSMV coat protein, which is presented on the VLP surface. Chemical conjugation reactions with this lysine proceed more quickly under alkaline conditions. Thus, our alkaline-stable VLP mutants are more suitable for rapid surface functionalization of long nanorods. This work validates novel residues involved in BSMV VLP assembly and demonstrates the feasibility of chemical functionalization of BSMV VLPs for the first time, enabling novel biomedical and chemical applications.

Facile Purification and Use of Tobamoviral Nanocarriers for Antibody-Mediated Display of a Two-Enzyme System

Immunosorbent turnip vein clearing virus (TVCV) particles displaying the IgG-binding domains D and E of Staphylococcus aureus protein A (PA) on every coat protein (CP) subunit (TVCVPA) were purified from plants via optimized and new protocols. The latter used polyethylene glycol (PEG) raw precipitates, from which virions were selectively re-solubilized in reverse PEG concentration gradients. This procedure improved the integrity of both TVCVPA and the wild-type subgroup 3 tobamovirus. TVCVPA could be loaded with more than 500 IgGs per virion, which mediated the immunocapture of fluorescent dyes, GFP, and active enzymes. Bi-enzyme ensembles of cooperating glucose oxidase and horseradish peroxidase were tethered together on the TVCVPA carriers via a single antibody type, with one enzyme conjugated chemically to its Fc region, and the other one bound as a target, yielding synthetic multi-enzyme complexes. In microtiter plates, the TVCVPA-displayed sugar-sensing system possessed a considerably increased reusability upon repeated testing, compared to the IgG-bound enzyme pair in the absence of the virus. A high coverage of the viral adapters was also achieved on Ta2O5 sensor chip surfaces coated with a polyelectrolyte interlayer, as a prerequisite for durable TVCVPA-assisted electrochemical biosensing via modularly IgG-assembled sensor enzymes.

Viral protein nanoparticles (Part 1): Pharmaceutical characteristics

Viral protein nanoparticles fill the gap between viruses and synthetic nanoparticles. Combining advantageous properties of both systems, they have revolutionized pharmaceutical research. Virus-like particles are characterized by a structure identical to viruses but lacking genetic material. Another type of viral protein nanoparticles, virosomes, are similar to liposomes but include viral spike proteins. Both systems are effective and safe vaccine candidates capable of overcoming the disadvantages of both traditional and subunit vaccines. Besides, their particulate structure, biocompatibility, and biodegradability make them good candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze viral protein nanoparticles from a pharmaceutical perspective and examine current research focused on their development process, from production to administration. Advances in synthesis, modification and formulation of viral protein nanoparticles are critical so that large-scale production of viral protein nanoparticle products becomes viable and affordable, which ultimately will increase their market penetration in the future. We will discuss their expression systems, modification strategies, formulation, biopharmaceutical properties, and biocompatibility.

Isopeptide Bonding In Planta Allows Functionalization of Elongated Flexuous Proteinaceous Viral Nanoparticles, including Non-Viable Constructs by Other Means

Plant viral nanoparticles (VNPs) have become an attractive platform for the development of novel nanotools in the last years because of their safety, inexpensive production, and straightforward functionalization. Turnip mosaic virus (TuMV) is one example of a plant-based VNP used as a nanobiotechnological platform either as virions or as virus-like particles (VLPs). Their functionalization mainly consists of coating their surface with the molecules of interest via chemical conjugation or genetic fusion. However, because of their limitations, these two methods sometimes result in non-viable constructs. In this paper, we applied the SpyTag/SpyCatcher technology as an alternative for the functionalization of TuMV VLPs with peptides and proteins. We chose as molecules of interest the green fluorescent protein (GFP) because of its good traceability, as well as the vasoactive intestinal peptide (VIP), given the previous unsuccessful attempts to functionalize TuMV VNPs by other methods. The successful conjugation of VLPs to GFP and VIP using SpyTag/SpyCatcher was confirmed through Western blot and electron microscopy. Moreover, the isopeptide bond between SpyTag and SpyCatcher occurred in vivo in co-agroinfiltrated Nicotiana benthamiana plants. These results demonstrated that SpyTag/SpyCatcher improves TuMV functionalization compared with previous approaches, thus implying the expansion of the application of the technology to elongated flexuous VNPs.

Convenient site-selective protein coupling from bacterial raw lysates to coenzyme A-modified tobacco mosaic virus (TMV) by Bacillus subtilis Sfp phosphopantetheinyl transferase

A facile enzyme-mediated strategy enables site-specific covalent one-step coupling of genetically tagged luciferase molecules to coenzyme A-modified tobacco mosaic virus (TMV-CoA) both in solution and on solid supports. Bacillus subtilis surfactin phosphopantetheinyl transferase Sfp produced in E. coli mediated the conjugation of firefly luciferase N-terminally extended by eleven amino acids forming a 'ybbR tag' as Sfp-selective substrate, which even worked in bacterial raw lysates. The enzymes displayed on the protein coat of the TMV nanocarriers exhibited high activity. As TMV has proven a beneficial high surface-area adapter template stabilizing enzymes in different biosensing layouts in recent years, the use of TMV-CoA for fishing ybbR-tagged proteins from complex mixtures might become an advantageous concept for the versatile equipment of miniaturized devices with biologically active proteins. It comes along with new opportunities for immobilizing multiple functionalities on TMV adapter coatings, as desired, e.g., in handheld systems for point-of-care detection.