Architectonics of phage-liposome nanowebs as optimized photosensitizer vehicles for photodynamic cancer therapy

Injectable Phage-Loaded Microparticles Effectively Release Phages to Kill Methicillin-Resistant Staphylococcus aureus

The increasing prevalence of bacterial multidrug antibiotic resistance has led to a serious threat to public health, emphasizing the urgent need for alternative antibacterial therapeutics. Lytic phages, a class of viruses that selectively infect and kill bacteria, offer promising potential as alternatives to antibiotics. However, injectable carriers with a desired release profile remain to be developed to deliver them to infection sites. To address this challenge, phage-loaded microparticles (Phage-MPs) have been developed to deliver phages to the infection site and release phages for an optimal therapeutic effect. The Phage-MPs are synthesized by allowing phages to be electrostatically attached onto the porous polyethylenimine-modified silk fibroin microparticles (SF-MPs). The high specific surface area of SF-MPs allows them to efficiently load phages, reaching about 1.25 × 1010 pfu per mg of microparticles. The Phage-MPs could release phages in a controlled manner to achieve potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Unlike the diffuse biodistribution of free phages post-intraperitoneal injection, Phage-MPs could continuously release phages to effectively boost the local phage concentration at the bacterial infection site after they are intraperitoneally injected into an abdominal MRSA-infected mouse model. In a mouse abdominal MRSA infection model, Phage-MPs significantly reduce the bacterial load in major organs, achieving an efficient therapeutic effect. Furthermore, Phage-MPs demonstrate outstanding biocompatibility both in vitro and in vivo. Overall, our research lays the foundation for a new generation of phage-based therapies to combat antibiotic-resistant bacterial infections.

Recent Progress in Phage-Based Nanoplatforms for Tumor Therapy

Nanodrug delivery systems have demonstrated a great potential for tumor therapy with the development of nanotechnology. Nonetheless, traditional drug delivery systems are faced with issues such as complex synthetic procedures, low reproducibility, nonspecific distribution, impenetrability of biological barrier, systemic toxicity, etc. In recent years, phage-based nanoplatforms have attracted increasing attention in tumor treatment for their regular structure, fantastic carrying property, high transduction efficiency and biosafety. Notably, therapeutic or targeting peptides can be expressed on the surface of the phages through phage display technology, enabling the phage vectors to possess multifunctions. As a result, the drug delivery efficiency on tumor will be vastly improved, thereby enhancing the therapeutic efficacy while reducing the side effects on normal tissues. Moreover, phages can overcome the hindrance of biofilm barrier to elicit antitumor effects, which exhibit great advantages compared with traditional synthetic drug delivery systems. Herein, this review not only summarizes the structure and biology of the phages, but also presents their potential as prominent nanoplatforms against tumor in different pathways to inspire the development of effective nanomedicine.

Living virus-based nanohybrids for biomedical applications

Living viruses characterized by distinctive biological functions including specific targeting, gene invasion, immune modulation, and so forth have been receiving intensive attention from researchers worldwide owing to their promising potential for producing numerous theranostic modalities against diverse pathological conditions. Nevertheless, concerns during applications, such as rapid immune clearance, altering immune activation modes, insufficient gene transduction efficiency, and so forth, highlight the crucial issues of excessive therapeutic doses and the associated biosafety risks. To address these concerns, synthetic nanomaterials featuring unique physical/chemical properties are frequently exploited as efficient drug delivery vehicles or treatments in biomedical domains. By constant endeavor, researchers nowadays can create adaptable living virus-based nanohybrids (LVN) that not only overcome the limitations of virotherapy, but also combine the benefits of natural substances and nanotechnology to produce novel and promising therapeutic and diagnostic agents. In this review, we discuss the fundamental physiochemical properties of the viruses, and briefly outline the basic construction methodologies of LVN. We then emphasize their distinct diagnostic and therapeutic performances for various diseases. Furthermore, we survey the foreseeable challenges and future perspectives in this interdisciplinary area to offer insights. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Therapeutic Approaches and Drug Discovery > Emerging Technologies.

A modular phage vector platform for targeted photodynamic therapy of Gram-negative bacterial pathogens

Growing antibiotic resistance has encouraged the revival of phage-inspired antimicrobial approaches. On the other hand, photodynamic therapy (PDT) is considered a very promising research domain for the protection against infectious diseases. Yet, very few efforts have been made to combine the advantages of both approaches in a modular, retargetable platform. Here, we foster the M13 bacteriophage as a multifunctional scaffold, enabling the selective photodynamic killing of bacteria. We took advantage of the well-defined molecular biology of M13 to functionalize its capsid with hundreds of photo-activable Rose Bengal sensitizers and contemporarily target this light-triggerable nanobot to specific bacterial species by phage display of peptide targeting moieties fused to the minor coat protein pIII of the phage. Upon light irradiation of the specimen, the targeted killing of diverse Gram(-) pathogens occurred at subnanomolar concentrations of the phage vector. Our findings contribute to the development of antimicrobials based on targeted and triggerable phage-based nanobiotherapeutics.

Genetic engineering of bacteriophages: Key concepts, strategies, and applications

Bacteriophages are the most abundant biological entity in the world and hold a tremendous amount of unexplored genetic information. Since their discovery, phages have drawn a great deal of attention from researchers despite their small size. The development of advanced strategies to modify their genomes and produce engineered phages with desired traits has opened new avenues for their applications. This review presents advanced strategies for developing engineered phages and their potential antibacterial applications in phage therapy, disruption of biofilm, delivery of antimicrobials, use of endolysin as an antibacterial agent, and altering the phage host range. Similarly, engineered phages find applications in eukaryotes as a shuttle for delivering genes and drugs to the targeted cells, and are used in the development of vaccines and facilitating tissue engineering. The use of phage display-based specific peptides for vaccine development, diagnostic tools, and targeted drug delivery is also discussed in this review. The engineered phage-mediated industrial food processing and biocontrol, advanced wastewater treatment, phage-based nano-medicines, and their use as a bio-recognition element for the detection of bacterial pathogens are also part of this review. The genetic engineering approaches hold great potential to accelerate translational phages and research. Overall, this review provides a deep understanding of the ingenious knowledge of phage engineering to move them beyond their innate ability for potential applications.

Cell primitive-based biomimetic functional materials for enhanced cancer therapy

Cell primitive-based functional materials that combine the advantages of natural substances and nanotechnology have emerged as attractive therapeutic agents for cancer therapy. Cell primitives are characterized by distinctive biological functions, such as long-term circulation, tumor specific targeting, immune modulation etc. Moreover, synthetic nanomaterials featuring unique physical/chemical properties have been widely used as effective drug delivery vehicles or anticancer agents to treat cancer. The combination of these two kinds of materials will catalyze the generation of innovative biomaterials with multiple functions, high biocompatibility and negligible immunogenicity for precise cancer therapy. In this review, we summarize the most recent advances in the development of cell primitive-based functional materials for cancer therapy. Different cell primitives, including bacteria, phages, cells, cell membranes, and other bioactive substances are introduced with their unique bioactive functions, and strategies in combining with synthetic materials, especially nanoparticulate systems, for the construction of function-enhanced biomaterials are also summarized. Furthermore, foreseeable challenges and future perspectives are also included for the future research direction in this field.

Enhancement of Photodynamic Cancer Therapy by Physical and Chemical Factors

The viable use of photodynamic therapy (PDT) in cancer therapy has never been fully realized because of its undesirable effects on healthy tissues. Herein we summarize some physicochemical factors that can make PDT a more viable and effective option to provide future oncological patients with better-quality treatment options. These physicochemical factors include light sources, photosensitizer (PS) carriers, microwaves, electric fields, magnetic fields, and ultrasound. This Review is meant to provide current information pertaining to PDT use, including a discussion of in vitro and in vivo studies. Emphasis is placed on the physicochemical factors and their potential benefits in overcoming the difficulty in transitioning PDT into the medical field. Many advanced techniques, such as employing X-rays as a light source, using nanoparticle-loaded stem cells and bacteriophage bio-nanowires as a photosensitizer carrier, as well as integration with immunotherapy, are among the future directions.

Integrating 3D Printing and Biomimetic Mineralization for Personalized Enhanced Osteogenesis, Angiogenesis, and Osteointegration

Titanium (Ti) alloy implants can repair bone defects at load-bearing sites. However, they mechanically mismatch with the natural bone and lack customized adaption with the irregularly major-sized load-bearing bone defects, resulting in the failure of implant fixation. Mineralized collagen (MC), a building block in bone, can induce angiogenesis and osteogenesis, and 3D printing technology can be employed to prepare scaffolds with an overall shape customized to the bone defect. Hence, we induced the formation of MC, made of hydroxyapatite (HAp) nanocrystals and collagen fibers, in 3D-printed porous Ti₆Al₄V (PT) scaffolds through in situ biomimetic mineralization. The resultant MC/PT scaffolds exhibited a bone-like Young's modulus and were customized to the anatomical contour of actual bone defects of rabbit model. We found that the biocompatibility and osteogenic differentiation are best when the mass ratio between HAp nanocrystals and collagen fibers is 1 in MC. We then implanted the MC/PT scaffolds into the customized radius defect rabbit model and found that the MC/PT scaffolds significantly improved the vascularized bone tissue formation and integration between new bone and the implants. Therefore, a combination of 3D printing and biomimetic mineralization could lead to customized 3D PT scaffolds for enhanced angiogenesis, osteogenesis, and osteointegration. Such scaffolds represent novel patient-specific implants for precisely repairing irregular major-sized load-bearing bone defects.

Multifunctional Electrospun Nanofibers for Enhancing Localized Cancer Treatment

Localized cancer treatment is one of the most effective strategies in clinical destruction of solid tumors at early stages as it can minimize the side effects of cancer therapeutics. Electrospun nanofibers have been demonstrated as a promising implantable platform in localized cancer treatment, enabling the on-site delivery of therapeutic components and minimizing side effects to normal tissues. This Review discusses the recent cutting-edge research with regard to electrospun nanofibers used for various therapeutic approaches, including gene therapy, chemotherapy, photodynamic therapy, thermal therapy, and combination therapy, in enhancing localized cancer treatment. Furthermore, it extensively analyzes the current challenges and potential breakthroughs in utilizing this novel platform for clinical transition in localized cancer treatment.

Honeysuckle flowers extract loaded Bombyx mori silk fibroin films for inducing apoptosis of HeLa cells

This study aimed to prepare silk fibroin (SF) films loaded with honeysuckle flowers extract (HFE) for inducing apoptosis of HeLa cells. We mixed solution of SF and HFE by air-drying for preparing the honeysuckle flowers extract loaded silk fibroin (SFH) films. The physical properties including morphologies, contact angle, roughness, and Z range were characterized. MTS assay and fluorescence micrographs proved that SFH films inhibited the proliferation rate of HeLa cells due to induction of HFE into SF films. Furthermore, cell apoptosis assay and cell cycle analysis confirmed that the apoptosis of HeLa cells resulted from SFH films. Therefore, SFH films designed in our study might be a promising candidate material for cancer therapy.

Drug delivery vectors based on filamentous bacteriophages and phage-mimetic nanoparticles

With the development of nanomedicine, a mass of nanocarriers have been exploited and utilized for targeted drug delivery, including liposomes, polymers, nanoparticles, viruses, and stem cells. Due to huge surface bearing capacity and flexible genetic engineering property, filamentous bacteriophage and phage-mimetic nanoparticles are attracting more and more attentions. As a rod-like bio-nanofiber without tropism to mammalian cells, filamentous phage can be easily loaded with drugs and directly delivered to the lesion location. In particular, chemical drugs can be conjugated on phage surface by chemical modification, and gene drugs can also be inserted into the genome of phage by recombinant DNA technology. Meanwhile, specific peptides/proteins displayed on the phage surface are able to conjugate with nanoparticles which will endow them specific-targeting and huge drug-loading capacity. Additionally, phage peptides/proteins can directly self-assemble into phage-mimetic nanoparticles which may be applied for self-navigating drug delivery nanovehicles. In this review, we summarize the production of phage particles, the identification of targeting peptides, and the recent applications of filamentous bacteriophages as well as their protein/peptide for targeting drug delivery in vitro and in vivo. The improvement of our understanding of filamentous bacteriophage and phage-mimetic nanoparticles will supply new tools for biotechnological approaches.

Bacteriophages in the human gut: Our fellow travelers throughout life and potential biomarkers of heath or disease

The gastrointestinal (GI) tract is populated by a huge variety of viruses. Bacterial viruses (bacteriophages) constitute the largest and the most unrecognized part of virome. The total bacteriophage community of the human gut is called phageome. Phages colonize the gut from the earliest moments of life and become our fellow travelers throughout life. Phageome seems to be unique to each individual and shows a high degree of interpersonal variation. In the healthy gut, a vast majority of phages have a lysogenic lifestyle. These prophages serve as a major respository of mobile genetic elements in the gut and play key roles in the exchange of genetic material between bacterial species via horizontal gene transfer (HGT). But, imbalance in the gut microbial community during dysbiosis, caused by diseases or environmental stresses such as antibiotics, is accompanied by induction of prophages leading to a decreased ratio of symbionts to pathobionts. Based on this, a diseased gut is transformed from an environment predominantly occupied by prophages to an ecosystem mostly inhabited by lytic phages. A growing body of evidence has provided support for the notion that phageome structure and composition change dependent on the physiological or pathological status of the body. This has been demonstrated by pronounced quantitative and qualitative differences between the phageome of healthy individuals and patients. Although many aspects of the contribution made by phages to human biology remain to be understood, recent findings favor the suggestion that phageome might represent potential to serve as a biomarker of health or disease.

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.

Engineering chemically modified viruses for prostate cancer cell recognition

Specific detection of circulating tumor cells and characterization of their aggressiveness could improve cancer diagnostics and treatment. Metastasis results from such tumor cells, and causes the majority of cancer deaths. Chemically modified viruses could provide an inexpensive and efficient approach to detect tumor cells and quantitate their cell surface biomarkers. However, non-specific adhesion between the cell surface receptors and the virus surface presents a challenge. This report describes wrapping the virus surface with different PEG architectures, including as fusions to oligolysine, linkers, spacers and scaffolded ligands. The reported PEG wrappers can reduce by >75% the non-specific adhesion of phage to cell surfaces. Dynamic light scattering verified the non-covalent attachment by the reported wrappers as increased sizes of the virus particles. Further modifications resulted in specific detection of prostate cancer cells expressing PSMA, a key prostate cancer biomarker. The approach allowed quantification of PSMA levels on the cell surface, and could distinguish more aggressive forms of the disease.

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.

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.

Tuning Endothelial Permeability with Functionalized Nanodiamonds

Cancer nanomedicine vehicles are required to cross the vascular barrier to reach the tumor site in order to ensure the successful delivery of their therapeutic load. Here, nanodiamond (ND) variants were shown to induce surface dependent vascular barrier leakiness. The ND-induced leakiness was found to be mediated by the increase in intracellular reactive oxygen species (ROS) and Ca(2+). These then in turn triggered the loss in endothelial cell-endothelial cell connections of the vascular barrier and also triggered their quasi-stable cytoskeletal remodelling. This ND driven increase in leakiness allowed more doxorubicin drug to penetrate through the vascular barrier to reach the cancer cells. This increase in the doxorubicin penetration subsequently led to an increase in the cancer killing effect. Overall, tuning the vascular barrier leakiness through ND surface group functionalization could provide an alternative strategy for the cancer nanomedicine to traverse across the vascular barrier.

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.

Selenite-Releasing Bone Mineral Nanoparticles Retard Bone Tumor Growth and Improve Healthy Tissue Functions In Vivo

Selenite-doped bone mineral nanoparticles can retard the growth of osteosarcoma in a nude mice model, through sustained release of selenite ions. The selenite ions released from the nanoparticles through a degradation-mediated fashion inhibit tumor metastasis. Blood routine analysis indicates that selenite ions can also improve the functions of liver, kidney, and heart.

Delivery of inhibitor of growth 4 (ING4) gene significantly inhibits proliferation and invasion and promotes apoptosis of human osteosarcoma cells

Growing evidence has suggested that inhibitor of growth 4 (ING4), a novel member of ING family proteins, plays a critical role in the development and progression of different tumors via multiple pathways. However, the function of ING4 in human osteosarcoma remains unclear. To understand its potential roles and mechanisms in inhibiting osteosarcoma, we constructed an expression vector pEGFP-ING4 and transfected the human osteosarcoma cells using this vector. We then studied the effects of over-expressed ING4 in the transfected cells on the proliferation, apoptosis and invasion of the osteosarcoma cells. The up-regulation of ING4 in the osteosarcoma cells, arising from the stable pEGFP-ING4 gene transfection, was found to significantly inhibit the cell proliferation by the cell cycle alteration with S phase reduction and G0/G1 phase arrest, induce cell apoptosis via the activation of the mitochondria pathway, and suppress cell invasion through the down-regulation of the matrix metalloproteinase 2 (MMP-2) and MMP-9 expression. In addition, increased ING4 level evoked the blockade of NF-κB signaling pathway and down-regulation of its target proteins. Our work suggests that ING4 can suppress osteosarcoma progression through signaling pathways such as mitochondria pathway and NF-κB signaling pathway and ING4 gene therapy is a promising approach to treating osteosarcoma.

Stem cells loaded with nanoparticles as a drug carrier for in vivo breast cancer therapy

A novel anti-cancer drug carrier, mesenchymal stem cells (MSCs) encapsulating drug-loaded hollow silica nanoparticles, is used to carry a photosensitizer drug and deliver it to breast tumors, due to the natural high tumor affinity of the MSCs, and inhibit tumor growth by photo dynamic therapy. This new strategy for delivering a photo sensitizer to tumors by using tumor-affinitive MSCs addresses the challenge of the accumulation of photosensitizer drugs in tumors in photodynamic therapy.

Current status of liposomal porphyrinoid photosensitizers

The complete eradication of various targets, such as infectious agents or cancer cells, while leaving healthy host cells untouched, is still a great challenge faced in the field of medicine. Photodynamic therapy (PDT) seems to be a promising approach for anticancer treatment, as well as to combat various dermatologic and ophthalmic diseases and microbial infections. The application of liposomes as delivery systems for porphyrinoids has helped overcome many drawbacks of conventional photosensitizers and facilitated the development of novel effective photosensitizers that can be encapsulated in liposomes. The development, preclinical studies and future directions for liposomal delivery of conventional and novel photosensitizers are reviewed.

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).