Nanofibrous bio-inorganic hybrid structures formed through self-assembly and oriented mineralization of genetically engineered phage nanofibers

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.

Peptide-based self-assembled monolayers (SAMs): what peptides can do for SAMs and vice versa

Self-assembled monolayers (SAMs) represent highly ordered molecular materials with versatile biochemical features and multidisciplinary applications. Research on SAMs has made much progress since the early begginings of Au substrates and alkanethiols, and numerous examples of peptide-displaying SAMs can be found in the literature. Peptides, presenting increasing structural complexity, stimuli-responsiveness, and biological relevance, represent versatile functional components in SAMs-based platforms. This review examines the major findings and progress made on the use of peptide building blocks displayed as part of SAMs with specific functions, such as selective cell adhesion, migration and differentiation, biomolecular binding, advanced biosensing, molecular electronics, antimicrobial, osteointegrative and antifouling surfaces, among others. Peptide selection and design, functionalisation strategies, as well as structural and functional characteristics from selected examples are discussed. Additionally, advanced fabrication methods for dynamic peptide spatiotemporal presentation are presented, as well as a number of characterisation techniques. All together, these features and approaches enable the preparation and use of increasingly complex peptide-based SAMs to mimic and study biological processes, and provide convergent platforms for high throughput screening discovery and validation of promising therapeutics and technologies.

Harnessing filamentous phages for enhanced stroke recovery

Stroke poses a critical global health challenge, leading to substantial morbidity and mortality. Existing treatments often miss vital timeframes and encounter limitations due to adverse effects, prompting the pursuit of innovative approaches to restore compromised brain function. This review explores the potential of filamentous phages in enhancing stroke recovery. Initially antimicrobial-centric, bacteriophage therapy has evolved into a regenerative solution. We explore the diverse role of filamentous phages in post-stroke neurological restoration, emphasizing their ability to integrate peptides into phage coat proteins, thereby facilitating recovery. Experimental evidence supports their efficacy in alleviating post-stroke complications, immune modulation, and tissue regeneration. However, rigorous clinical validation is essential to address challenges like dosing and administration routes. Additionally, genetic modification enhances their potential as injectable biomaterials for complex brain tissue issues. This review emphasizes innovative strategies and the capacity of filamentous phages to contribute to enhanced stroke recovery, as opposed to serving as standalone treatment, particularly in addressing stroke-induced brain tissue damage.

Engineered M13 phage as a novel therapeutic bionanomaterial for clinical applications: From tissue regeneration to cancer therapy

Bacteriophages (phages) are nanostructured viruses with highly selective antibacterial properties that have gained attention beyond eliminating bacteria. Specifically, M13 phages are filamentous phages that have recently been studied in various aspects of nanomedicine due to their biological advantages and more compliant engineering capabilities over other phages. Having nanofiber-like morphology, M13 phages can reach varied target sites and self-assemble into multidimensional scaffolds in a relatively safe and stable way. In addition, genetic modification of the coat proteins enables specific display of peptides and antibodies on the phages, allowing for precise and individualized medicine. M13 phages have also been subjected to novel engineering approaches, including phage-based bionanomaterial engineering and phage-directed nanomaterial combinations that enhance the bionanomaterial properties of M13 phages. In view of these features, researchers have been able to utilize M13 phages for therapeutic applications such as drug delivery, biodetection, tissue regeneration, and targeted cancer therapy. In particular, M13 phages have been utilized as a novel bionanomaterial for precisely mimicking natural tissue environment in order to overcome the shortage in tissue and organ donors. Hence, in this review, we address the recent studies and advances of using M13 phages in the field of nanomedicine as therapeutic agents based upon their characteristics as novel bionanomaterial with biomolecules displayed. This paper also emphasizes the novel engineering approach that enhances M13 phage's bionanomaterial capabilities. Current limitations and future approaches are also discussed to provide insight in further progress for M13 phage-based clinical applications.

Phage for regenerative medicine and cosmetics

Phage or bacteriophage is a specific virus with the ability to defeat bacteria. Because of the rising prevalence of antimicrobial-resistant bacteria, the bacteriophage is now receiving interest again, with it application in skin infection or acne treatment. Moreover, bacteriophages also express their efficacy in wound healing or skin regeneration. Thanks to the development of bioengineering technology, phage display, which is a technique using bacteriophage as a tool, has recently been applied in many biotechnological and medical fields, especially in regenerative medicines. Bacteriophages can be used as nanomaterials, delivery vectors, growth factor alternatives, or in several bacteriophage display-derived therapeutics and stem cell technology. Although bacteriophage is no doubt to be a potential and effective alternative in modern medicine, there are still controversial evidence about the antibacterial efficacy as well as the affinity to expected targets of bacteriophage. Future mission is to optimize the specificity, stability, affinity and biodistribution of phage-derived substances. In this chapter, we focused on introducing several mechanisms and applications of bacteriophage and analyzing its future potential in regenerative medicines as well as cosmetics via previous research's results.

Perspectives on using bacteriophages in biogerontology research and interventions

With the development of materials engineering, gerontology-related research on new tools for diagnostic and therapeutic applications, including precision and personalised medicine, has expanded significantly. Using nanotechnology, drugs can be precisely delivered to organs, tissues, cells, and cell organelles, thereby enhancing their therapeutic effects. Here, we discuss the possible use of bacteriophages as nanocarriers that can improve the safety, efficiency, and sensitivity of conventional medical therapies. Phages are a new class of targeted-delivery vectors, which can carry high concentrations of cargo and protect other nontargeted cells from the senescent cell killing effects of senolytics. Bacteriophages can also be subjected to chemical and/or genetic modifications that would acquire novel properties and improve their ability to detect senescent cells and deliver senolytics. Phage research in experimental biogerontology will also develop strategies to efficiently deliver senolytics, target senescent cells, activate extrinsic apoptosis pathways in senescent cells, trigger immune cells to recognise senescent cells, induce autophagy, promote cell and tissue regeneration, inhibit senescence-associated secretory phenotype (SASP) by senomorphic activity, stimulate the properties of mild stress-inducing hormetic agents and hormetins, and modulate the gut microbiome.

Natural protein-based electrospun nanofibers for advanced healthcare applications: progress and challenges

Electrospinning is an electrostatic fiber fabrication technique that operates by the application of a strong electric field on polymer solution or melts. It is used to fabricate fibers whose size lies in the range of few microns to the nanometer range. Historic development of electrospinning has evinced attention due to its outstanding attributes such as small diameter, excellent pore inter-connectivity, high porosity, and high surface-to-volume ratio. This review aims to highlight the theory behind electrospinning and the machine setup with a detailed discussion about the processing parameters. It discusses the latest innovations in natural protein-based electrospun nanofibers for health care applications. Various plant- and animal-based proteins have been discussed with detailed sample preparation and corresponding processing parameters. The usage of these electrospun nanofibers in regenerative medicine and drug delivery has also been discussed. Some technical innovations in electrospinning techniques such as emulsion electrospinning and coaxial electrospinning have been highlighted. Coaxial electrospun core-shell nanofibers have the potential to be utilized as an advanced nano-architecture for sustained release targeted delivery as well as for regenerative medicine. Healthcare applications of nanofibers formed via emulsion and coaxial electrospinning have been discussed briefly. Electrospun nanofibers have still much scope for commercialization on large scale. Some of the available wound-dressing materials have been discussed in brief.

Attachment of Ultralow Amount of Engineered Plant Viral Nanoparticles to Mesenchymal Stem Cells Enhances Osteogenesis and Mineralization

Hydrogel-based materials are widely used to mimic the extracellular matrix in bone tissue engineering, although they often lack biofunctional cues. In the authors' previous work, Potato virus X (PVX), a flexible rod-shaped biocompatible plant virus nanoparticle (VNP) with 1270 coat protein subunits, is genetically modified to present functional peptides for generating a bone substitute. Here, PVX is engineered to present mineralization- and osteogenesis-associated peptides and laden in hydrogels at a concentration lower by two orders of magnitude. Its competence in mineralization is demonstrated both on 2D surfaces and in hydrogels and the superiority of enriched peptides on VNPs is verified and compared with free peptides and VNPs presenting fewer functional peptides. Alkaline phosphatase activity and Alizarin red staining of human mesenchymal stem cells increase 1.2-1.7 times when stimulate by VNPs. Engineered PVX adheres to cells, exhibiting a stimulation of biomimetic peptides in close proximity to the cells. The retention of VNPs in hydrogels is monitored and more than 80% of VNPs remain inside after several washing steps. The mechanical properties of VNP-laden hydrogels are investigated, including viscosity, gelling temperature, and compressive tangent modulus. This study demonstrates that recombinant PVX nanoparticles are excellent candidates for hydrogel nanocomposites in bone tissue engineering.

Virus-Incorporated Biomimetic Nanocomposites for Tissue Regeneration

Owing to the astonishing properties of non-harmful viruses, tissue regeneration using virus-based biomimetic materials has been an emerging trend recently. The selective peptide expression and enrichment of the desired peptide on the surface, monodispersion, self-assembly, and ease of genetic and chemical modification properties have allowed viruses to take a long stride in biomedical applications. Researchers have published many reviews so far describing unusual properties of virus-based nanoparticles, phage display, modification, and possible biomedical applications, including biosensors, bioimaging, tissue regeneration, and drug delivery, however the integration of the virus into different biomaterials for the application of tissue regeneration is not yet discussed in detail. This review will focus on various morphologies of virus-incorporated biomimetic nanocomposites in tissue regeneration and highlight the progress, challenges, and future directions in this area.

Bacteriophage-based biomaterials for tissue regeneration

Bacteriophage, also called phage, is a human-safe bacteria-specific virus. It is a monodisperse biological nanostructure made of proteins (forming the outside surface) and nucleic acids (encased in the protein capsid). Among different types of phages, filamentous phages have received great attention in tissue regeneration research due to their unique nanofiber-like morphology. They can be produced in an error-free format, self-assemble into ordered scaffolds, display multiple signaling peptides site-specifically, and serve as a platform for identifying novel signaling or homing peptides. They can direct stem cell differentiation into specific cell types when they are organized into proper patterns or display suitable peptides. These unusual features have allowed scientists to employ them to regenerate a variety of tissues, including bone, nerves, cartilage, skin, and heart. This review will summarize the progress in the field of phage-based tissue regeneration and the future directions in this field.

Self-Assembled Nanoporous Biofilms from Functionalized Nanofibrous M13 Bacteriophage

Highly periodic and uniform nanostructures, based on a genetically engineered M13 bacteriophage, displayed unique properties at the nanoscale that have the potential for a variety of applications. In this work, we report a multilayer biofilm with self-assembled nanoporous surfaces involving a nanofiber-like genetically engineered 4E-type M13 bacteriophage, which was fabricated using a simple pulling method. The nanoporous surfaces were effectively formed by using the networking-like structural layers of the M13 bacteriophage during self-assembly. Therefore, an external template was not required. The actual M13 bacteriophage-based fabricated multilayered biofilm with porous nanostructures agreed well with experimental and simulation results. Pores formed in the final layer had a diameter of about 150–500 nm and a depth of about 15–30 nm. We outline a filter application for this multilayered biofilm that enables selected ions to be extracted from a sodium chloride solution. Here, we describe a simple, environmentally friendly, and inexpensive fabrication approach with large-scale production potential. The technique and the multi-layered biofilms produced may be applied to sensor, filter, plasmonics, and bio-mimetic fields.

Progress Toward the Clinical Translation of Bioinspired Peptide and Protein Assemblies

Supramolecular materials composed of proteins and peptides have been receiving considerable attention toward a range of diseases and conditions from vaccines to drug delivery. Owing to the relative newness of this class of materials, the bulk of work to date has been preclinical. However, examples of approved treatments particularly in vaccines, dentistry, and hemostasis demonstrate the translational potential of supramolecular polypeptides. Critical milestones in the clinical development of this class of materials and currently approved supramolecular polypeptide therapies are described in this study. Additional examples of not-yet-approved materials that are steadily advancing toward clinical use are also featured. Spherical assemblies such as virus-like particles, designed protein nanoparticles, and spherical peptide amphiphiles are highlighted, followed by fiber-forming systems such as fibrillizing peptides, fiber-forming peptide-amphiphiles, and filamentous bacteriophages.

Ternary Aligned Nanofibers of RGD Peptide-Displaying M13 Bacteriophage/PLGA/Graphene Oxide for Facilitated Myogenesis

Recently, there have been tremendous efforts to develop the biofunctional scaffolds by incorporating various biochemical factors. In the present study, we fabricated poly(lactic-co-glycolic acid) (PLGA) nanofiber sheets decorated with graphene oxide (GO) and RGD peptide. The decoration of GO and RGD peptide was readily achieved by using RGD peptide-displaying M13 bacteriophage (RGD-M13 phage) and electrospinning. Furthermore, the aligned GO-decorated PLGA/RGD peptide (GO-PLGA/RGD) ternary nanofiber sheets were prepared by magnetic field-assisted electrospinning, and their potentials as bifunctional scaffolds for facilitating myogenesis were explored. We characterized the physicochemical and mechanical properties of the sheets by scanning electron microscopy, Raman spectroscopy, contact angle measurement, and tensile test. In addition, the C2C12 skeletal myoblasts were cultured on the aligned GO-PLGA/RGD nanofiber sheets, and their cellular behaviors, including initial attachment, proliferation and myogenic differentiation, were evaluated. Our results revealed that the GO-PLGA/RGD nanofiber sheets had suitable physicochemical and mechanical properties for supporting cell growth, and could significantly promote the spontaneous myogenic differentiation of C2C12 skeletal myoblasts. Moreover, it was revealed that the myogenic differentiation was further accelerated on the aligned GO-PLGA/RGD nanofiber sheets due to the synergistic effects of RGD peptide, GO and aligned nanofiber structure. Therefore, , it is suggested that the aligned GO-PLGA/RGD ternary nanofiber sheets are one of the most promising approaches for facilitating myogenesis and promoting skeletal tissue regeneration.

Silica formation with nanofiber morphology via helical display of the silaffin R5 peptide on a filamentous bacteriophage

Biological systems often generate unique and useful structures, which can have industrial relevance either as direct components or as an inspiration for biomimetic materials. For fabrication of nanoscale silica structures, we explored the use of the silaffin R5 peptide from Cylindrotheca fusiformis expressed on the surface of the fd bacteriophage. By utilizing the biomineralizing peptide component displayed on the bacteriophage surface, we found that low concentrations (0.09 mg/mL of the R5 bacteriophage, below the concentration range used in other studies) could be used to create silica nanofibers. An additional benefit of this approach is the ability of our R5-displaying phage to form silica materials without the need for supplementary components, such as aminopropyl triethoxysilane, that are typically used in such processes. Because this method for silica formation can occur under mild conditions when implementing our R5 displaying phage system, we may provide a relatively simple, economical, and environmentally friendly process for creating silica nanomaterials.

Phage-Enabled Nanomedicine: From Probes to Therapeutics in Precision Medicine

Both lytic and temperate bacteriophages (phages) can be applied in nanomedicine, in particular, as nanoprobes for precise disease diagnosis and nanotherapeutics for targeted disease treatment. Since phages are bacteria-specific viruses, they do not naturally infect eukaryotic cells and are not toxic to them. They can be genetically engineered to target nanoparticles, cells, tissues, and organs, and can also be modified with functional abiotic nanomaterials for disease diagnosis and treatment. This Review will summarize the current use of phage structures in many aspects of precision nanomedicine, including ultrasensitive biomarker detection, enhanced bioimaging for disease diagnosis, targeted drug and gene delivery, directed stem cell differentiation, accelerated tissue formation, effective vaccination, and nanotherapeutics for targeted disease treatment. We will also propose future directions in the area of phage-based nanomedicines, and discuss the state of phage-based clinical trials.

Identification of Novel Short BaTiO3-Binding/Nucleating Peptides for Phage-Templated in Situ Synthesis of BaTiO3 Polycrystalline Nanowires at Room Temperature

Ferroelectric materials, such as tetragonal barium titanate (BaTiO3), have been widely used in a variety of areas including bioimaging, biosensing, and high power switching devices. However, conventional methods for the synthesis of tetragonal phase BaTiO3 usually require toxic organic reagents and high temperature treatments, and are thus not environment-friendly and energy-efficient. Here, we took advantage of the phage display technique to develop a novel strategy for the synthesis of BaTiO3 nanowires. We identified a short BaTiO3-binding/nucleating peptide, CRGATPMSC (named RS), from a phage-displayed random peptide library by biopanning technique and then genetically fused the peptide to the major coat protein (pVIII) of filamentous M13 phages to form the pVIII-RS phages. We found that the resultant phages could not only bind with the presynthesized BaTiO3 crystals but also induce the nucleation of uniform tetragonal BaTiO3 nanocrystals at room temperature and without the use of toxic reagents to form one-dimensional polycrystalline BaTiO3 nanowires. This approach enables the green synthesis of BaTiO3 polycrystalline nanowires with potential applications in bioimaging and biosensing fields.

Bacteriophages and phage-inspired nanocarriers for targeted delivery of therapeutic cargos

The main goal of drug delivery systems is to target therapeutic cargoes to desired cells and to ensure their efficient uptake. Recently a number of studies have focused on designing bio-inspired nanocarriers, such as bacteriophages, and synthetic carriers based on the bacteriophage structure. Bacteriophages are viruses that specifically recognize their bacterial hosts. They can replicate only inside their host cell and can act as natural gene carriers. Each type of phage has a particular shape, a different capacity for loading cargo, a specific production time, and their own mechanisms of supramolecular assembly, that have enabled them to act as tunable carriers. New phage-based technologies have led to the construction of different peptide libraries, and recognition abilities provided by novel targeting ligands. Phage hybridization with non-organic compounds introduces new properties to phages and could be a suitable strategy for construction of bio-inorganic carriers. In this review we try to cover the major phage species that have been used in drug and gene delivery systems, and the biological application of phages as novel targeting ligands and targeted therapeutics.

Design of virus-based nanomaterials for medicine, biotechnology, and energy

This review provides an overview of recent developments in "chemical virology." Viruses, as materials, provide unique nanoscale scaffolds that have relevance in chemical biology and nanotechnology, with diverse areas of applications. Some fundamental advantages of viruses, compared to synthetically programmed materials, include the highly precise spatial arrangement of their subunits into a diverse array of shapes and sizes and many available avenues for easy and reproducible modification. Here, we will first survey the broad distribution of viruses and various methods for producing virus-based nanoparticles, as well as engineering principles used to impart new functionalities. We will then examine the broad range of applications and implications of virus-based materials, focusing on the medical, biotechnology, and energy sectors. We anticipate that this field will continue to evolve and grow, with exciting new possibilities stemming from advancements in the rational design of virus-based nanomaterials.

Phage as a Genetically Modifiable Supramacromolecule in Chemistry, Materials and Medicine

Filamentous bacteriophage (phage) is a genetically modifiable supramacromolecule. It can be pictured as a semiflexible nanofiber (∼900 nm long and ∼8 nm wide) made of a DNA core and a protein shell with the former genetically encoding the latter. Although phage bioengineering and phage display techniques were developed before the 1990s, these techniques have not been widely used for chemistry, materials, and biomedical research from the perspective of supramolecular chemistry until recently. Powered by our expertise in displaying a foreign peptide on its surface through engineering phage DNA, we have employed phage to identify target-specific peptides, construct novel organic-inorganic nanohybrids, develop biomaterials for disease treatment, and generate bioanalytical methods for disease diagnosis. Compared with conventional biomimetic chemistry, phage-based supramolecular chemistry represents a new frontier in chemistry, materials science, and medicine. In this Account, we introduce our recent successful efforts in phage-based supramolecular chemistry, by integrating the unique nanofiber-like phage structure and powerful peptide display techniques into the fields of chemistry, materials science, and medicine: (1) successfully synthesized and assembled silica, hydroxyapatite, and gold nanoparticles using phage templates to form novel functional materials; (2) chemically introduced azo units onto the phage to form photoresponsive functional azo-phage nanofibers via a diazotization reaction between aromatic amino groups and the tyrosine residues genetically displayed on phage surfaces; (3) assembled phage into 2D films for studying the effects of both biochemical (the peptide sequences displayed on the phages) and biophysical (the topographies of the phage films) cues on the proliferation and differentiation of mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs) and identified peptides and topographies that can induce their osteogenic differentiation; (4) discovered that phage could induce angiogenesis and osteogenesis for MSC-based vascularized bone regeneration; (5) identified novel breast cancer cell-targeting and MSC-targeting peptides and used them to significantly improve the efficiency of targeted cancer therapy and MSC-based gene delivery, respectively; (6) employed engineered phage as a probe to achieve ultrasensitive detection of biomarkers from serum of human patients for disease diagnosis; and (7) constructed centimeter-scale 3D multilayered phage assemblies with the potential application as scaffolds for bone regeneration and functional device fabrication. Our findings demonstrated that phage is indeed a very powerful supramacromolecule suitable for not only developing novel nanostructures and biomaterials but also advancing important fields in biomedicine, including molecular targeting, cancer diagnosis and treatment, drug and gene delivery, stem cell fate direction, and tissue regeneration. Our successes in exploiting phage in chemistry, materials, and medicine suggest that phage itself is nontoxic at the cell level and can be safely used for detecting biomarkers in vitro. Moreover, although we have demonstrated successful in vivo tissue regeneration induced by phage, we believe future studies are needed to evaluate the in vivo biodistribution and potential risks of the phage-based biomaterials.

Chemically Modifying Viruses for Diverse Applications

Long fascinating to biologists, viruses offer nanometer-scale benchtops for building molecular-scale devices and materials. Viruses tolerate a wide range of chemical modifications including reaction conditions, pH values, and temperatures. Recent examples of nongenetic manipulation of viral surfaces have extended viruses into applications ranging from biomedical imaging, drug delivery, tissue regeneration, and biosensors to materials for catalysis and energy generation. Chemical reactions on the phage surface include both covalent and noncovalent modifications, including some applied in conjunction with genetic modifications. Here, we survey viruses chemically augmented with capabilities limited only by imagination.

Genetically Engineered Virus Nanofibers as an Efficient Vaccine for Preventing Fungal Infection

Candida albicans (CA) is a kind of fungus that can cause high morbidity and mortality in immunocompromised patients. However, preventing CA infection in these patients is still a daunting challenge. Herein, inspired from the fact that immunization with secreted aspartyl proteinases 2 (Sap2) can prevent the infection, it is proposed to use filamentous phage, a human-safe virus nanofiber specifically infecting bacteria (≈900 nm long and 7 nm wide), to display an epitope peptide of Sap2 (EPS, with a sequence of Val-Lys-Tyr-Thr-Ser) on its side wall and thus serve as a vaccine for preventing CA infection. The engineered virus nanofibers and recombinant Sap2 (rSap2) are then separately used to immunize mice. The humoral and cellular immune responses in the immunized mice are evaluated. Surprisingly, the virus nanofibers significantly induce mice to produce strong immune response as rSap2 and generate antibodies that can bind Sap2 and CA to inhibit the CA infection. Consequently, immunization with the virus nanofibers in mice dramatically increases the survival rate of CA-infected mice. All these results, along with the fact that the virus nanofibers can be mass-produced by infecting bacteria cost-effectively, suggest that virus nanofibers displaying EPS can be a vaccine candidate against fungal infection.

Filamentous supramolecular structures with polyelectrolyte and cadmium sulfide

In this study, a new type of filamentous structures consisting of a generation 9 poly(amido amine) dendrimer (G9) and CdS is reported. The linearity of the interconnected dendrimers is a result of the electrostatic repulsion between the multiply charged dendrimer macroions. Structures have been investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The internal structure of the CdS-fibers reveals information on the mechanism of the fiber formation. In contrast to previous systems with smaller generation poly(propylene imine)-dendrimers, Cd(2+) is here found to be responsible for the interconnection of G9. Furthermore, more complex supramolecular structures were built by associating the CdS-dendrimer hybrid fibers with different ionic dyes, displaying the versatility of this system for future nanotechnology applications such as optoelectronics or energy conversion.

Surfactant-Free Vanadium Oxides from Reverse Micelles and Organic Oxidants: Solution Processable Nanoribbons with Potential Applicability as Battery Insertion Electrodes Assembled in Different Configurations

Vanadium oxides similar to other metal transition oxides are prototypes of multifunctionality. Implementing new synthesis routes that lead to dry vanadium oxide nanomaterials with good functional and structural properties as well as good processing capabilities is thus of general interest. Here we report a facile method based on reverse micelles for the growth at room temperature and atmospheric pressure of surfactant-free vanadium oxide nanoribbons that retain after drying excellent solution-processable capabilities. Essential for the success of the method is the use of a soluble organic oxidant that acts as oxidant and cosurfactant during the synthesis, and facilitates surfactant removal with a simple washing protocol. Interestingly, this simple surfactant removal protocol could be of general applicability. As a proof-of-concept of the functional, structural, and processing capabilities of the dry vanadium oxide nanoribbons here prepared, we have checked their lithium insertion capabilities as battery cathodes built upon different configurations. Specifically, we show efficient insertion both in dry nanoribbons processed as films using doctor blade and organic solvents and in dry nanoribbons infiltrated in three-dimensional metal collectors from aqueous suspensions.

Cellulose Nanocrystals--Bioactive Glass Hybrid Coating as Bone Substitutes by Electrophoretic Co-deposition: In Situ Control of Mineralization of Bioactive Glass and Enhancement of Osteoblastic Performance

Surface functionalization of orthopedic implants is being intensively investigated to strengthen bone-to-implant contact and accelerate bone healing process. A hybrid coating, consisting of 45S5 bioactive glass (BG) individually wrapped and interconnected with fibrous cellulose nanocrystals (CNCs), is deposited on 316L stainless steel from aqueous suspension by a one-step electrophoretic deposition (EPD) process. Apart from the codeposition mechanism elucidated by means of zeta-potential and scanning electron microscopy measurements, in vitro characterization of the deposited CNCs-BG coating in simulated body fluid reveals an extremely rapid mineralization of BG particles on the coating (e.g., the formation of hydroxyapatite crystals layer after 0.5 day). A series of comparative trials and characterization methods were carried out to comprehensively understand the mineralization process of BG interacting with CNCs. Furthermore, key factors for satisfying the applicability of an implant coating such as coating composition, surface topography, and adhesion strength were quantitatively investigated as a function of mineralization time. Cell culture studies (using MC3T3-E1) indicate that the presence of CNCs-BG coating substantially accelerated cell attachment, spreading, proliferation, differentiation, and mineralization of extracellular matrix. This study has confirmed the capability of CNCs to enhance and regulate the bioactivity of BG particles, leading to mineralized CNCs-BG hybrids for improved bone implant coatings.

Green Synthesis of Metallic Nanoparticles via Biological Entities

Nanotechnology is the creation, manipulation and use of materials at the nanometre size scale (1 to 100 nm). At this size scale there are significant differences in many material properties that are normally not seen in the same materials at larger scales. Although nanoscale materials can be produced using a variety of traditional physical and chemical processes, it is now possible to biologically synthesize materials via environment-friendly green chemistry based techniques. In recent years, the convergence between nanotechnology and biology has created the new field of nanobiotechnology that incorporates the use of biological entities such as actinomycetes algae, bacteria, fungi, viruses, yeasts, and plants in a number of biochemical and biophysical processes. The biological synthesis via nanobiotechnology processes have a significant potential to boost nanoparticles production without the use of harsh, toxic, and expensive chemicals commonly used in conventional physical and chemical processes. The aim of this review is to provide an overview of recent trends in synthesizing nanoparticles via biological entities and their potential applications.

Chimeric Protein Template-Induced Shape Control of Bone Mineral Nanoparticles and Its Impact on Mesenchymal Stem Cell Fate

Protein-mediated molecular self-assembly has become a powerful strategy to fabricate biomimetic biomaterials with controlled shapes. Here we designed a novel chimeric molecular template made of two proteins, silk fibroin (SF) and albumin (ALB), which serve as a promoter and an inhibitor for hydroxyapatite (HA) formation, respectively, to synthesize HA nanoparticles with controlled shapes. HA nanospheres were produced by the chimeric ALB-SF template, whereas HA nanorods were generated by the SF template alone. The success in controlling the shape of HA nanoparticles allowed us to further study the effect of the shape of HA nanoparticles on the fate of rat mesenchymal stem cells (MSCs). We found that the nanoparticle shape had a crucial impact on the cellular uptake and HA nanospheres were internalized in MSCs at a faster rate. Both HA nanospheres and nanorods showed no significant influence on cell proliferation and migration. However, HA nanospheres significantly promoted the osteoblastic differentiation of MSCs in comparison to HA nanorods. Our work suggests that a chimeric combination of promoter and inhibitor proteins is a promising approach to tuning the shape of nanoparticles. It also sheds new light into the role of the shape of the HA nanoparticles in directing stem cell fate.

Ca2+-induced self-assembly of Bombyx mori silk sericin into a nanofibrous network-like protein matrix for directing controlled nucleation of hydroxylapatite nano-needles

Bone biomineralization is a well-regulated protein-mediated process where hydroxylapatite (HAP) crystals are nucleated with preferred orientation within self-assembled protein matrix. Mimicking this process is a promising approach to the production of bone-like protein/mineral nanocomposites for bone repair and regeneration. Towards the goal of fabricating such nanocomposites from sericin, a protein spun by Bombyx mori (B.mori) silkworm, and bone mineral HAP, for the first time we investigated the chemical mechanism underpinning the synergistic processes of the conformational change/self-assembly of B.mori sericin ( BS ) as well as the nucleation of HAP on the resultant self-assembled BS matrix. We found that BS , rich in anionic amino acid residues, could bind Ca²⁺ ions from the HAP precursor solution through electrostatic attraction. The Ca²⁺binding drove the conformational change of BS from random coils into β-sheets and its concomitant self-assembly into interconnected nanofibrous network-like protein matrix, which initiated the nucleation and growth of HAP crystals. HAP crystals directed by the resultant self-assembled BS matrix grew preferentially along their crystallographic c-axis, leading to the formation of HAP nano-needles. The HAP nano-needles in the self-assembled BS matrix were subsequently aggregated into globules, probably driven by the hydrogen bonding between C=O groups of BS and O-H groups of HAP nano-needles. The present work sheds light on the chemical mechanisms of BS self-assembly and the controlled mineralization directed by the self-assembled matrix. We also found that the resultant nanocomposites could promote the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells. Thus our work also generates a biomimetic approach to bone-like silk protein/mineral nanocomposite scaffolds that can find potential applications in bone repair and regeneration.

Adsorption and self-assembly of M13 phage into directionally organized structures on C and SiO2 films

A versatile method for the directional assembly of M13 phage using amorphous carbon and SiO2 thin films was demonstrated. A high affinity of the M13 phage macromolecules for incorporation into aligned structures on an amorphous carbon surface was observed at the concentration range, in which the viral nanofibers tend to disorder. In contrast, the viral particles showed less freedom to adopt an aligned orientation on SiO2 films when deposited in close vicinity. Here an interpretation of the role of the carbon surface in significant enhancement of adsorption and generation of viral arrays with a high orientational order was proposed in terms of surface chemistry and competitive electrostatic interactions. This study suggests the use of amorphous carbon substrates as a template for directional organization of a closely-packed and two-dimensional M13 viral film, which can be a promising route to mineralize a variety of smooth and homogeneous inorganic nanostructure layers.

Stable biofunctionalization of hydroxyapatite (HA) surfaces by HA-binding/osteogenic modular peptides for inducing osteogenic differentiation of mesenchymal stem cells

Hydroxyapatite (HA), the principal component of bone mineral, shows osteoconductive properties when employed for coating metal implants as well as scaffold materials in synthetic bone grafts. With the goal of providing this material with osteoinductive capabilities to promote faster bone regeneration, we show an easy approach to functionalize HA implant surfaces and enrich them with osteoinductive properties by the use of HA-binding modular peptides. The modular peptides are designed as a combination of two domains, an HA-binding peptide motif and an osteogenic peptide motif derived from the osteogenic growth peptide (OGP) or bone morphometric protein 7 (BMP-7). To identify the best HA-binding peptide, several nature-inspired peptides derived from natural bone extracellular matrix proteins (bone sialoprotein, osteonectin, osteocalcin, and salivarin statherin) were compared for HA-binding activity, revealing concentration-dependent and incubation-time-dependent behaviours. We discovered that a Poly-E heptamer (E7) is the best HA-binding peptide, and thus combined it with a second osteogenic peptidic domain to create an osteoinductive modular peptide. After binding/release characterization, we found that the addition of the second osteogenic peptide domain did not change the binding profile of the modular peptides and caused only a slight change in their release kinetics. Mesenchymal stem cells (MSCs) were cultured on the HA substrates functionalized with modular peptides, and cell adhesion, proliferation, and differentiation in a basal medium (i.e., without any osteogenic supplements) were investigated. Gene expression data clearly showed that MSCs were committed to differentiate into osteoblasts in the presence of the modular peptides. HA discs functionalized with the E7 BMP-7 modular peptide showed the best capability in inducing the osteogenic differentiation of MSCs among all modular peptides studied. The modular peptides can easily be used to functionalize the HA implants through its constituent HA-binding motif, leaving the osteogenic peptide motif protruding from the surface for inducing osteogenesis. Our work opens up a new approach to the formulation of new bioactive HA coatings and implants for bone and dental repair.

Phage nanofibers induce vascularized osteogenesis in 3D printed bone scaffolds

A virus-activated matrix is developed to overcome the challenge of forming vascularized bone tissue. It is generated by filling a 3D printed bioceramic scaffold with phage nanofibers displaying high-density RGD peptide. After it is seeded with mesenchymal stem cells (MSCs) and implanted into a bone defect, the phage nanofibers induce osteogenesis and angiogenesis by activating endothelialization and osteogenic differentiation of MSCs.

Phage-based nanomaterials for biomedical applications

Recent advances in nanotechnology enable us to manipulate and produce materials with molecular level control. In the newly emerging field of bionanomedicine, it is essential to precisely control the physical, chemical and biological properties of materials. Among other biological building blocks, viruses are a promising nanomaterial that can be functionalized with great precision. Since the production of viral particles is directed by the genetic information encapsulated in their protein shells, the viral particles create precisely defined sizes and shapes. In addition, the composition and surface properties of the particles can be controlled through genetic engineering and chemical modification. In this manuscript, we review the advances of virus-based nanomaterials for biomedical applications in three different areas: phage therapy, drug delivery and tissue engineering. By exploiting and manipulating the original functions of viruses, viral particles hold great possibilities in these biomedical applications to improve human health.

Biomimetic nucleation of hydroxyapatite crystals mediated by Antheraea pernyi silk sericin promotes osteogenic differentiation of human bone marrow derived mesenchymal stem cells

Biomacromolecules have been used as templates to grow hydroxyapatite crystals (HAps) by biomineralization to fabricate mineralized materials for potential application in bone tissue engineering. Silk sericin is a protein with features desirable as a biomaterial, such as increased hydrophilicity and biodegradation. Mineralization of the silk sericin from Antheraea pernyi (A. pernyi) silkworm has rarely been reported. Here, for the first time, nucleation of HAps on A. pernyi silk sericin (AS) was attempted through a wet precipitation method and consequently the cell viability and osteogenic differentiation of BMSCs on mineralized AS were investigated. It was found that AS mediated the nucleation of HAps in the form of nanoneedles while self-assembling into β-sheet conformation, leading to the formation of a biomineralized protein based biomaterial. The cell viability assay of BMSCs showed that the mineralization of AS stimulated cell adhesion and proliferation, showing that the resultant AS biomaterial is biocompatible. The differentiation assay confirmed that the mineralized AS significantly promoted the osteogenic differentiation of BMSCs when compared to nonmineralized AS as well as other types of sericin (B. mori sericin), suggesting that the resultant mineralized AS biomaterial has potential in promoting bone formation. This result represented the first work proving the osteogenic differentiation of BMSCs directed by silk sericin. Therefore, the biomineralization of A. pernyi silk sericin coupled with seeding BMSCs on the resultant mineralized biomaterials is a useful strategy to develop the potential application of this unexplored silk sericin in the field of bone tissue engineering. This study lays the foundation for the use of A. pernyi silk sericin as a potential scaffold for tissue engineering.

Tuning nano-architectures and improving bioactivity of conducting polypyrrole coating on bone implants by incorporating bone-borne small molecules

Citric acid, a molecule present in fresh bone, was introduced into template-free electrochemical polymerization to form biocompatible coating made of polypyrrole (PPy) nano-cones on bone implants. It served not only as a dopant to tune the nano-architectures but also as a promoter to enhance bioactivity of the PPy-coated implants.

Phage as a template to grow bone mineral nanocrystals

Phage display is a biotechnique that fuses functional peptides on the outer surface of filamentous phage by inserting DNA encoding the peptides into the genes of its coat proteins. The resultant peptide-displayed phage particles have been widely used as biotemplates for the synthesis of functional hybrid nanomaterials. Here, we describe the bioengineering of M13 filamentous phage to surface-display bone mineral (hydroxyapatite (HAP))-nucleating peptides derived from dentin matrix protein-1 and using the engineered phage as a biotemplate to grow HAP nanocrystals.

The Role of Poly(Aspartic Acid) in the Precipitation of Calcium Phosphate in Confinement

Many questions remain regarding the formation of ultrathin hydroxapatite (HAP) crystals within the confines of collagen fibrils of bones. These structures form through the interplay of the collagen matrix and non-collagenous proteins, and in vitro mineralization studies employing poly(aspartic acid) (PAsp) as a mimic of the non-collagenous proteins have generated mineralized fibrils with structures comparable to their biogenic counterparts. In this article, we employ the nanoscale cylindrical pores perforating track-etch filtration membranes to investigate the role of PAsp in controlling the infiltration and crystallization of calcium phosphate (CaP) within confined volumes. Oriented polycrystalline HAP and non-oriented octacalcium phosphate (OCP) rods precipitated within the membrane pores via an amorphous calcium phosphate (ACP) precursor, where PAsp increased the proportion of OCP rods. Further, ACP crystallized faster within the membranes than in bulk solution when PAsp was present, suggesting that PAsp inhibits crystallization in solution, but promotes it when bound to a substrate. Finally, in contrast to the collagen system, PAsp reduced the yield of intra-membrane mineral and failed to enhance infiltration. This suggests that a specific interaction between the collagen matrix and ACP/PAsp precursor particles drives effective infiltration. Thus, while orientation of HAP crystals can be achieved by confinement alone, the chemistry of the collagen matrix is necessary for efficient mineralisation with CaP.

Virus-based photo-responsive nanowires formed by linking site-directed mutagenesis and chemical reaction

Owing to the genetic flexibility and error-free bulk production, bio-nanostructures such as filamentous phage showed great potential in materials synthesis, however, their photo-responsive behaviour is neither explored nor unveiled. Here we show M13 phage genetically engineered with tyrosine residues precisely fused to the major coat protein is converted into a photo-responsive organic nanowire by a site-specific chemical reaction with an aromatic amine to form an azo dye structure on the surface. The resulting azo-M13-phage nanowire exhibits reversible photo-responsive properties due to the photo-switchable cis-trans isomerisation of the azo unit formed on the phage. This result shows that site-specific display of a peptide on bio-nanostructures through site-directed genetic mutagenesis can be translated into site-directed chemical reaction for developing advanced materials. The photo-responsive properties of the azo-M13-phage nanowires may open the door for the development of light controllable smart devices for use in non-linear optics, holography data storage, molecular antenna, and actuators.

Nanoscale confinement controls the crystallization of calcium phosphate: relevance to bone formation

A key feature of biomineralization processes is that they take place within confined volumes, in which the local environment can have significant effects on mineral formation. Herein, we investigate the influence of confinement on the formation mechanism and structure of calcium phosphate (CaP). This is of particular relevance to the formation of dentine and bone, structures of which are based on highly mineralized collagen fibrils. CaP was precipitated within 25-300 nm diameter, cylindrical pores of track etched and anodised alumina membranes under physiological conditions, in which this system enables systematic study of the effects of the pore size in the absence of a structural match between the matrix and the growing crystals. Our results show that the main products were polycrystalline hydroxapatite (HAP) rods, together with some single crystal octacalcium phosphate (OCP) rods. Notably, we demonstrate that these were generated though an intermediate amorphous calcium phosphate (ACP) phase, and that ACP is significantly stabilised in confinement. This effect may have significance to the mineralization of bone, which can occur through a transient ACP phase. We also show that orientation of the HAP comparable, or even superior to that seen in bone can be achieved through confinement effects alone. Although this simple experimental system cannot be considered, a direct mimic of the in vivo formation of ultrathin HAP platelets within collagen fibrils, our results show that the effects of physical confinement should not be neglected when considering the mechanisms of formation of structures, such as bones and teeth.

Phage-directed synthesis of copper sulfide: structural and optical characterization

The growth of crystalline copper sulfide using a viral template was investigated using sequential incubation in CuCl2 and Na2S precursors. Non-specific electrostatic attraction between a genetically-modified M13 bacteriophage and copper cations in the CuCl2 precursor caused phage agglomeration and bundle formation. Following the addition of Na2S, polydisperse nanocrystals 2-7 nm in size were found along the length of the viral scaffold. The structure of the copper sulfide material was identified as cubic anti-fluorite type Cu1.8S, space group Fm3[overline]m. Strong interband absorption was observed within the ultraviolet to visible range with an onset near 800 nm. Furthermore, free carrier absorption, associated with the localized surface plasmon resonance of the copper sulfide nanocrystals, was seen in the near infrared with absorbance maxima at 1060 nm and 3000 nm, respectively.

Naturally and synthetic smart composite biomaterials for tissue regeneration

The development of smart biomaterials for tissue regeneration has become the focus of intense research interest. More opportunities are available by the composite approach of combining the biomaterials in the form of biopolymers and/or bioceramics either synthetic or natural. Strategies to provide smart capabilities to the composite biomaterials primarily seek to achieve matrices that are instructive/inductive to cells, or that stimulate/trigger target cell responses that are crucial in the tissue regeneration processes. Here, we review in-depth, recent developments concerning smart composite biomaterials available for delivery systems of biofactors and cells and scaffolding matrices in tissue engineering. Smart composite designs are possible by modulating the bulk and surface properties that mimic the native tissues, either in chemical (extracellular matrix molecules) or in physical properties (e.g. stiffness), or by introducing external therapeutic molecules (drugs, proteins and genes) within the structure in a way that allows sustainable and controllable delivery, even time-dependent and sequential delivery of multiple biofactors. Responsiveness to internal or external stimuli, including pH, temperature, ionic strength, and magnetism, is another promising means to improve the multifunctionality in smart scaffolds with on-demand delivery potential. These approaches will provide the next-generation platforms for designing three-dimensional matrices and delivery systems for tissue regenerative applications.

Bacteriophage bionanowire as a carrier for both cancer-targeting peptides and photosensitizers and its use in selective cancer cell killing by photodynamic therapy

A photosensitizer, pyropheophorbid-a (PPa), is conjugated to SKBR-3 breast cancer cell-specific biological nanowire phage, to form a novel PPa-phage complex, which is further successfully used in selectively killing SKBR-3 breast cancer cells by the mechanism of photodynamic therapy (PDT).

Assembly of bacteriophage into functional materials

For the last decade, the fabrication of ordered structures of phage has been of great interest as a means of utilizing the outstanding biochemical properties of phage in developing useful materials. Combined with other organic/inorganic substances, it has been demonstrated that phage is a superior building block for fabricating various functional devices, such as the electrode in lithium-ion batteries, photovoltaic cells, sensors, and cell-culture supports. Although previous research has expanded the utility of phage when combined with genetic engineering, most improvements in device functionality have relied upon increases in efficiency owing to the compact, more densely packable unit size of phage rather than on the unique properties of the ordered nanostructures themselves. Recently, self-templating methods, which control both thermodynamic and kinetic factors during the deposition process, have opened up new routes to exploiting the ordered structural properties of hierarchically organized phage architectures. In addition, ordered phage films have exhibited unexpected functional properties, such as structural color and optical filtering. Structural colors or optical filtering from phage films can be used for optical phage-based sensors, which combine the structural properties of phage with target-specific binding motifs on the phage-coat proteins. This self-templating method may contribute not only to practical applications, but also provide insight into the fundamental study of biomacromolecule assembly in in vivo systems under complicated and dynamic conditions.

Flagellar display of bone-protein-derived peptides for studying peptide-mediated biomineralization

A bacterial flagellum is self-assembled primarily from thousands of flagellin (FliC), a protein subunit. A foreign peptide can be fully displayed on the surface of the flagellum through inserting it into every constituent protein subunit. To shed light on the role of bone proteins during the nucleation of hydroxyapatite (HAP), representative domains from type I collagen, including part of the N-,C-terminal, N-,C-zone around the hole zone and an eight repeat unit Gly-Pro-Pro (GPP8) sequence similar to the central sequence of type I collagen, were separately displayed on the surface of the flagella. Moreover, eight negatively charged, contiguous glutamic acid residues (E8) and two other characteristic sequences derived from a representative noncollagenous protein called bone sialoprotein (BSP) were also displayed on flagella. After being incubated in an HAP supersaturated precursor solution, flagella displaying E8 or GPP8 sequences were found to be coated with a layer of HAP nanocrystals. Very weak or no nucleation was observed on flagella displaying other peptides being tested. We also found that calcium ions can induce the assembly of the negatively charged E8 flagella into bundles mimicking collagen fibers, followed by the formation of HAP nanocrystals with the crystallographic c axis preferentially aligned with long axis of flagella, which is similar to that along the collagen fibrils in bone. This work demonstrates that because of the ease of the peptide display on flagella and the self-assembly of flagella, flagella can serve as a platform for studying biomineralization and as a building block to generate bonelike biomaterials.

Tools from viruses: bacteriophage successes and beyond

Viruses are ubiquitous and can infect any of the three existing cellular lineages (Archaea, Bacteria and Eukarya). Despite the persisting negative public perception of these entities, scientists learnt how to domesticate some of them. The study of molecular mechanisms essential to the completion of viral cycles has greatly contributed to deciphering fundamental processes in biology. Nowadays, viruses have entered the biotechnological era and numerous applications have already been developed. Viral-derived tools are used to manipulate genetic information, detect, diagnose, control and cure infectious diseases, or even design new structural assemblies. With the recent advances in the field of metagenomics, an overwhelming amount of information on novel viruses has become available. As current tools have been historically developed from a limited number of viruses, the potential of discoveries from new archaeal, bacterial and eukaryotic viruses may be limited only by our understanding of the multiple facets of viral cycles.

The role of nanoscale architecture in supramolecular templating of biomimetic hydroxyapatite mineralization

Understanding and mimicking the hierarchical structure of mineralized tissue is a challenge in the field of biomineralization and is important for the development of scaffolds to guide bone regeneration. Bone is a remarkable tissue with an organic matrix comprised of aligned collagen bundles embedded with nanometer-sized inorganic hydroxyapatite (HAP) crystals that exhibit orientation on the macroscale. Hybrid organic-inorganic structures mimic the composition of mineralized tissue for functional bone scaffolds, but the relationship between morphology of the organic matrix and orientation of mineral is poorly understood. Herein the mineralization of supramolecular peptide amphiphile templates, that are designed to vary in nanoscale morphology by altering the amino acid sequence, is reported. It is found that 1D cylindrical nanostructures direct the growth of oriented HAP crystals, while flatter nanostructures fail to guide the orientation found in biological systems. The geometric constraints associated with the morphology of the nanostructures may effectively control HAP nucleation and growth. Additionally, the mineralization of macroscopically aligned bundles of the nanoscale assemblies to create hierarchically ordered scaffolds is explored. Again, it is found that only aligned gel templates of cylindrical nanostructures lead to hierarchical control over hydroxyapatite orientation across multiple length scales as found in bone.

Controlling nanostructures of mesoporous silica fibers by supramolecular assembly of genetically modifiable bacteriophages

A useful virus: The synthesis of a new family of mesoporous silica fibers is reported. Monodisperse filamentous bacteriophages self-assembled into highly ordered hexagonal lattices that were used as templates for the formation of silica nanostructures. Removal of the bacteriophage assembly through calcination led to the formation of mesoporous silica fibers with pore structures precisely defined by the bacteriophage assembly (see picture).