Engineering nanoparticle-coated bacteria as oral DNA vaccines for cancer immunotherapy

Surface-functionalized bacteria: Frontier explorations in next-generation live biotherapeutics

Screening robust living bacteria to produce living biotherapeutic products (LBPs) represents a burgeoning research field in biomedical applications. Despite their natural abilities to colonize bio-interfaces and proliferate, harnessing bacteria for such applications is hindered by considerable challenges in unsatisfied functionalities and safety concerns. Leveraging the high degree of customization and adaptability on the surface of bacteria demonstrates significant potential to improve therapeutic outcomes and achieve tailored functionalities of LBPs. This review focuses on the recent laboratory strategies of bacterial surface functionalization, which aims to address these challenges and potentiate the therapeutic effects in biomedicine. Firstly, we introduce various functional materials that are used for bacterial surface functionalization involving organic, inorganic, and biological materials. Secondly, the methodologies for achieving bacterial surface functionalization are categorized into three primary approaches including covalent bonding, non-covalent interactions, and hybrid techniques, while various advantages and limitations of different modification strategies are compared from multiple perspectives. Subsequently, the current status of the applications of surface-functionalized bacteria in bioimaging and disease treatments, especially in the treatment of inflammatory bowel disease (IBD) and cancer is summarized. Finally, challenges and pressing issues in the development of surface-functionalized bacteria as LBPs are presented.

Creation of Artificial Subcellular Organelles Using Compartmentalized Escherichia coli Bodies for Artificial Metalloenzyme-Mediated Abiotic Catalysis in Eukaryotic Cells

Artificial metalloenzymes (ArMs) stand out as excellent tools mediating intracellular abiotic transformations due to their multifaceted advantages, including their adaptability through directed evolution and availability as whole-cell catalysts. However, the applications of ArMs as exogenous agents in eukaryotic systems remain challenging due to issues with protein purification and delivery, metalloenzyme stability, and complex catalyst preparation. In this article, we present a method inspired by nature's endosymbiotic process, enabling the direct use of ArMs residing within the bacterial cells that express them as whole-cell-based catalytic platforms in eukaryotic cells. This approach utilizes HaloTag-SNAPTag fusion protein as the ArM scaffold, which undergoes liquid-liquid phase separation to form sanctuaries in Escherichia coli for different ArMs created from the same fusion protein. Such compartmentalized E. coli are then sterilized and granted cell permeability with polymer decoration so that they may enter eukaryotic cells and work as artificial subcellular organelles, mediating abiotic transformations using those well-protected ArMs residing within. We further demonstrate the potential of this strategy in therapeutic applications in proof-of-concept demonstrations, by showing that these encapsulated ArMs can be viable options for intracellular bacterial pathogen elimination and cancer therapy through prodrug activation in live cells and animals. Likely, this strategy will suggest a different pathway for expanding ArM applications in chemical biology and biomedicine.

Synthetic and Biogenic Materials for Oral Delivery of Biologics: From Bench to Bedside

The development of nucleic acid and protein drugs for oral delivery has lagged behind their production for conventional nonoral routes. Over the past decade, the evolution of DNA- and RNA-based technologies combined with the innovation of state-of-the-art delivery vehicles for nucleic acids has brought rapid advancements to the biopharmaceutical field. Nucleic acid therapies have the potential to achieve long-lasting effects, or even cures, by inhibiting or editing genes, which is not possible with conventional small-molecule drugs. However, challenges and limitations must be addressed before these therapies can provide cures for chronic conditions and rare diseases, rather than only offering temporary relief. Nucleic acids and proteins face premature degradation in the acidic, enzyme-rich stomach environment and are rapidly cleared by the liver. To overcome these challenges, various delivery vehicles have been developed to transport therapeutic compounds to the intestines, where the active compounds are released and gut microbiota and mucosal immune system also play an important role. This review provides a comprehensive overview of the promises and pitfalls associated with the oral route of administration of biologics, current delivery systems, applications of orally delivered therapeutics, and the challenges and considerations for translation of nucleic acid and protein therapeutics into clinical practice.

The potential use of bacteria and their derivatives as delivery systems for nanoparticles in the treatment of cancer

Cancer is a leading cause of mortality and morbidity worldwide. Nanomaterials, unique optical, magnetic, and electrical properties at the nanoscale (1-100 nm), have been engineered to improve drug capacity, bioavailability, and specificity in cancer treatment. These advancements address toxicity and lack of selectivity in conventional therapies, enabling precise targeting of cancer cells, the tumour microenvironment, and the immune system. Among emerging approaches, bacterial treatment shows promise due to its natural ability to target cancer and its diverse therapeutic mechanisms, which nanotechnology can further enhance. Bacteria-based drug delivery systems leverage bacteria's adaptability and survival strategies within the human body. Bacterial derivatives, such as bacterial ghosts (BGs), bacterial extracellular vesicles (BEVs), and dietary toxins, are recognised as effective biological nanomaterials capable of carrying nanoparticles (NPs). These systems have attracted increasing attention for their potential in targeted NP delivery for cancer treatment. This study explores the use of various bacteria and their byproducts as NP delivery vehicles, highlighting their potential in treating different types of cancer. By combining the strengths of nanotechnology and bacterial therapy, these innovative approaches aim to revolutionise cancer treatment with improved precision and efficacy.

Nanoparticle-mediated enhancement of DNA Vaccines: Revolutionizing immunization strategies

DNA vaccines are a novel form of vaccination that aims to harness genetic material to produce targeted immune responses. Nevertheless, their therapeutic application is hampered by low transfection efficacy, immunogenicity, and instability. Nanoparticle (NP) - based delivery systems are beneficial in enhancing DNA stability, increasing DNA uptake by antigen-presenting cells (APCs), and controlling antigen release. Some key progress includes the polymeric, lipid-based, and hybrid NPs and biocompatible carriers with inherent adjuvant effects. These systems have helped to enhance the antigen cross-presentation and T-cell activation significantly. In addition, biocompatible hybrid nanocarriers, antigen cross-presentation strategies, and next-generation sequencing (NGS) technologies are speeding up the identification of new antigens, while AI and machine learning are facilitating the development of efficient delivery systems. This review aims to assess how NPs have contributed to improving the effectiveness of DNA vaccines for treating diseases, cancer, and emerging diseases, as well as advancing the next generation of DNA vaccines.

Bacterial and bacterial derivatives-based drug delivery systems: a novel approach for treating central nervous system disorders

INTRODUCTION

Bacteria and their derivatives show great potential as drug delivery systems due to their unique chemotaxis, biocompatibility, and targeting abilities. In CNS disease treatment, bacterial carriers can cross the blood-brain barrier (BBB) and deliver drugs precisely, overcoming limitations of traditional methods. Advances in genetic engineering, synthetic biology, and nanotechnology have transformed these systems into multifunctional platforms for personalized CNS treatment.

AREAS COVERED

This review examines the latest research on bacterial carriers for treating ischemic brain injury, neurodegenerative diseases, and gliomas. Bacteria efficiently cross the blood-brain barrier via active targeting, endocytosis, paracellular transport, and the nose-to-brain route for precise drug delivery. Various bacterial drug delivery systems, such as OMVs and bacterial ghosts, are explored for their design and application. Databases were searched in Google Scholar for the period up to December 2024.

EXPERT OPINION

Future developments in bacterial drug delivery will rely on AI-driven design and high-throughput engineering, enhancing treatment precision. Personalized medicine will further optimize bacterial carriers for individual patients, but challenges such as biosafety, immune rejection, and scalability must be addressed. As multimodal diagnostic and therapeutic strategies advance, bacterial carriers are expected to play a central role in CNS disease treatment, offering novel precision medicine solutions.

DNA vaccines as promising immuno-therapeutics against cancer: a new insight

Cancer is one of the leading causes of mortality around the world and most of our conventional treatments are not efficient enough to combat this deadly disease. Harnessing the power of the immune system to target cancer cells is one of the most appealing methods for cancer therapy. Nucleotide-based cancer vaccines, especially deoxyribonucleic acid (DNA) cancer vaccines are viable novel cancer treatments that have recently garnered significant attention. DNA cancer vaccines are made of plasmid molecules that encode tumor-associated or tumor-specific antigens (TAAs or TSAs), and possibly some other immunomodulatory adjuvants such as pro-inflammatory interleukins. Following the internalization of plasmids into cells, their genes are expressed and the tumor antigens are loaded on major histocompatibility molecules to be presented to T-cells. After the T-cells have been activated, they will look for tumor antigens and destroy the tumor cells upon encountering them. As with any other treatment, there are pros and cons associated with using these vaccines. They are relatively safe, usually well-tolerated, stable, easily mass-produced, cost-effective, and easily stored and transported. They can induce a systemic immune response effective on both the primary tumor and metastases. The main disadvantage of DNA vaccines is their poor immunogenicity. Several approaches including structural modification, combination therapy with conventional and novel cancer treatments (such as chemotherapy, radiotherapy, and immune checkpoint blockade (ICB)), and the incorporation of adjuvants into the plasmid structure have been studied to enhance the vaccine's immunogenicity and improve the clinical outcome of cancer patients. In this review, we will discuss some of the most promising optimization strategies and examine some of the important trials regarding these vaccines.

Genetically engineered gas vesicle proteins with proliferative potential for synergistic targeted tumor therapy

Nanomedicine enables precision-targeted therapies through a non-invasive approach, and nanoparticles may be biologically affected during their colonization in vivo. Ensuring the efficient expression of their ex vivo performance in vivo, while ensuring biosafety, is of great significance. Previous studies have employed genetically engineered E. coli following in vivo entry as a genetically engineered targeting synergist, to enhance the effect of focused ultrasound ablation by exploiting its targeted colonization of tumor tissue. However, the proliferation process of the actual potentiating nanomaterials, i.e., the aerosol proteins produced by genetically engineered E. coli, in vivo has not been precisely observed. The authors of this paper demonstrate this spatiotemporal change in the expression of gas vesicle proteins while genetically engineered E. coli reproduces following tumor colonization. Based on their targeting and proliferative properties, the authors chose to intervene in the treatment at the maximal gas vesicle protein count to enhance the monitoring and utilization of the potentiator. By examining the therapeutic potential of the novel combination of genetic engineering and focused ultrasound, we present a robust strategy that improves the efficiency of non-invasive treatments.

Microbial messengers: nucleic acid delivery by bacteria

The demand for diverse nucleic acid delivery vectors, driven by recent biotechnological breakthroughs, offers opportunities for continuous improvements in efficiency, safety, and delivery capacity. With their enhanced safety and substantial cargo capacity, bacterial vectors offer significant potential across a variety of applications. In this review, we explore methods to engineer bacteria for nucleic acid delivery, including strategies such as engineering attenuated strains, lysis circuits, and conjugation machinery. Moreover, we explore pioneering techniques, such as manipulating nanoparticle (NP) coatings and outer membrane vesicles (OMVs), representing the next frontier in bacterial vector engineering. We foresee these advancements in bacteria-mediated nucleic acid delivery, through combining bacterial pathogenesis with engineering biology techniques, as a pivotal step forward in the evolution of nucleic acid delivery technologies.

DNA-amphiphilic nanostructures: synthesis, characterization and applications

DNA's extraordinary potential reaches far beyond its role as a carrier of genetic information. It serves as a remarkably adaptable structural foundation for constructing intricate nanostructures with a diverse range of functionalities. This inherent programmability sets DNA apart from other biomolecules like peptides, proteins, and small molecules. By covalently attaching DNA to synthetic hydrophobic moieties, researchers create DNA amphiphiles capable of interacting with artificial lipid bilayers and cell membranes. These hybrid structures have rapidly gained prominence due to their promising potential in the medical field. This review provides a comprehensive overview of the latest advancements in the synthesis of DNA amphiphiles and their assembly into well-defined nanostructures. It explores the diverse applications of these nanostructures across various medical domains, including targeted drug delivery, innovative immunotherapies, and gene-silencing techniques. Moreover, the review delves into the current challenges and prospects of this rapidly evolving field, highlighting the potential of DNA hybrid materials to revolutionize medical treatments and diagnostics. By addressing the limitations and exploring new avenues of research, scientists aim to unlock the full potential of DNA nanotechnology for the benefit of human health.

Advancing vaccine technology through the manipulation of pathogenic and commensal bacteria

Advancements in vaccine technology are increasingly focused on leveraging the unique properties of both pathogenic and commensal bacteria. This revolutionary approach harnesses the diverse immune modulatory mechanisms and bacterial biology inherent in different bacterial species enhancing vaccine efficacy and safety. Pathogenic bacteria, known for their ability to induce robust immune responses, are being studied for their potential to be engineered into safe, attenuated vectors that can target specific diseases with high precision. Concurrently, commensal bacteria, which coexist harmlessly with their hosts and contribute to immune system regulation, are also being explored as novel delivery systems and in microbiome-based therapy. These bacteria can modulate immune responses, offering a promising avenue for developing effective and personalized vaccines. Integrating the distinctive characteristics of pathogenic and commensal bacteria with advanced bacterial engineering techniques paves the way for innovative vaccine and therapeutic platforms that could address a wide range of infectious diseases and potentially non-infectious conditions. This holistic approach signifies a paradigm shift in vaccine development and immunotherapy, emphasizing the intricate interplay between the bacteria and the immune systems to achieve optimal immunological outcomes.

Probiotic bacterial adsorption coupled with CRISPR/Cas12a system for mercury (II) ions detection

The complex sample matrix poses significant challenges in accurately detecting heavy metals. In view of its superior performance for the biological adsorption of heavy metals, probiotic bacteria can be explored for functional unit to eliminate matrix interference. Herein, Lactobacillus rhamnosus (LGG) demonstrates a remarkable tolerance and can adsorb up to 300 μM of Hg2+, following the Freundlich isotherm model with the correlation coefficient (R2) value of 0.9881. Subsequently, by integrating the CRISPR/Cas12a system, a sensitive and specific fluorescent biosensor, "Cas12a-MB," has been developed for Hg2+ detection. Specifically, Hg2+ adsorbed onto LGG can specifically bind to the nucleic acid probe, thereby inhibiting the binding of the probe to LGG and the subsequent activation of the CRISPR/Cas12a system. Under optimal experimental conditions, with the detection time of 90 min and the detection limit of 0.44 nM, the "Cas12a-MB" biosensor offers a novel, eco-friendly approach for Hg2+ detection, showcasing the innovative application of probiotics in biosensor.

Nanomaterial combined engineered bacteria for intelligent tumor immunotherapy

Cancer remains the leading cause of human death worldwide. Compared to traditional therapies, tumor immunotherapy has received a lot of attention and research focus due to its potential to activate both innate and adaptive immunity, low toxicity to normal tissue, and long-term immune activity. However, its clinical effectiveness and large-scale application are limited due to the immunosuppression microenvironment, lack of spatiotemporal control, expensive cost, and long manufacturing time. Recently, nanomaterial combined engineered bacteria have emerged as a promising solution to the challenges of tumor immunotherapy, which offers spatiotemporal control, reversal of immunosuppression, and scalable production. Therefore, we summarize the latest research on nanomaterial-assisted engineered bacteria for precise tumor immunotherapies, including the cross-talk of nanomaterials and bacteria as well as their application in different immunotherapies. In addition, we further discuss the advantages and challenges of nanomaterial-engineered bacteria and their future prospects, inspiring more novel and intelligent tumor immunotherapy.

Beyond the Gut: The intratumoral microbiome's influence on tumorigenesis and treatment response

The intratumoral microbiome (TM) refers to the microorganisms in the tumor tissues, including bacteria, fungi, viruses, and so on, and is distinct from the gut microbiome and circulating microbiota. TM is strongly associated with tumorigenesis, progression, metastasis, and response to therapy. This paper highlights the current status of TM. Tract sources, adjacent normal tissue, circulatory system, and concomitant tumor co-metastasis are the main origin of TM. The advanced techniques in TM analysis are comprehensively summarized. Besides, TM is involved in tumor progression through several mechanisms, including DNA damage, activation of oncogenic signaling pathways (phosphoinositide 3-kinase [PI3K], signal transducer and activator of transcription [STAT], WNT/β-catenin, and extracellular regulated protein kinases [ERK]), influence of cytokines and induce inflammatory responses, and interaction with the tumor microenvironment (anti-tumor immunity, pro-tumor immunity, and microbial-derived metabolites). Moreover, promising directions of TM in tumor therapy include immunotherapy, chemotherapy, radiotherapy, the application of probiotics/prebiotics/synbiotics, fecal microbiome transplantation, engineered microbiota, phage therapy, and oncolytic virus therapy. The inherent challenges of clinical application are also summarized. This review provides a comprehensive landscape for analyzing TM, especially the TM-related mechanisms and TM-based treatment in cancer.

Harnessing Bacterial Membrane Components for Tumor Vaccines: Strategies and Perspectives

Tumor vaccines stand at the vanguard of tumor immunotherapy, demonstrating significant potential and promise in recent years. While tumor vaccines have achieved breakthroughs in the treatment of cancer, they still encounter numerous challenges, including improving the immunogenicity of vaccines and expanding the scope of vaccine application. As natural immune activators, bacterial components offer inherent advantages in tumor vaccines. Bacterial membrane components, with their safer profile, easy extraction, purification, and engineering, along with their diverse array of immune components, activate the immune system and improve tumor vaccine efficacy. This review systematically summarizes the mechanism of action and therapeutic effects of bacterial membranes and its derivatives (including bacterial membrane vesicles and hybrid membrane biomaterials) in tumor vaccines. Subsequently, the authors delve into the preparation and advantages of tumor vaccines based on bacterial membranes and hybrid membrane biomaterials. Following this, the immune effects of tumor vaccines based on bacterial outer membrane vesicles are elucidated, and their mechanisms are explained. Moreover, their advantages in tumor combination therapy are analyzed. Last, the challenges and trends in this field are discussed. This comprehensive analysis aims to offer a more informed reference and scientific foundation for the design and implementation of bacterial membrane-based tumor vaccines.

Engineered Cancer Nanovaccines: A New Frontier in Cancer Therapy

Vaccinations are essential for preventing and treating disease, especially cancer nanovaccines, which have gained considerable interest recently for their strong anti-tumor immune capabilities. Vaccines can prompt the immune system to generate antibodies and activate various immune cells, leading to a response against tumor tissues and reducing the negative effects and recurrence risks of traditional chemotherapy and surgery. To enhance the flexibility and targeting of vaccines, nanovaccines utilize nanotechnology to encapsulate or carry antigens at the nanoscale level, enabling more controlled and precise drug delivery to enhance immune responses. Cancer nanovaccines function by encapsulating tumor-specific antigens or tumor-associated antigens within nanomaterials. The small size of these nanomaterials allows for precise targeting of T cells, dendritic cells, or cancer cells, thereby eliciting a more potent anti-tumor response. In this paper, we focus on the classification of carriers for cancer nanovaccines, the roles of different target cells, and clinically tested cancer nanovaccines, discussing strategies for effectively inducing cytotoxic T lymphocytes responses and optimizing antigen presentation, while also looking ahead to the translational challenges of moving from animal experiments to clinical trials.

Enteral Route Nanomedicine for Cancer Therapy

With the in-depth knowledge of the pathological and physiological characteristics of the intestinal barrier-portal vein/intestinal lymphatic vessels-systemic circulation axis, oral targeted drug delivery is frequently being renewed. With many advantages, such as high safety, convenient administration, and good patient compliance, many researchers have begun to explore targeted drug delivery from intravenous injections to oral administration. Over the past few decades, the fields of materials science and nanomedicine have produced various drug delivery platforms that hold great potential in overcoming the multiple barriers associated with oral drug delivery. However, the oral transport of particles into the systemic circulation is extremely difficult due to immune rejection and biochemical invasion in the intestine, which limits absorption and entry into the bloodstream. The feasibility of the oral delivery of targeted drugs to sites outside the gastrointestinal tract (GIT) is unknown. This article reviews the biological barriers to drug absorption, the in vivo fate and transport mechanisms of drug carriers, the theoretical basis for oral administration, and the impact of carrier structural evolution on oral administration to achieve this goal. Finally, this article reviews the characteristics of different nano-delivery systems that can enhance the bioavailability of oral therapeutics and highlights their applications in the efficient creation of oral anticancer nanomedicines.

A promising strategy to improve the stability and immunogenicity of killed but metabolically active vaccines: low-temperature preparation and coating of nanoparticles

Bacteria are becoming an increasingly serious threat to human health. The emergence of super bacteria makes clinical treatment more difficult. Vaccines are one of the most effective means of preventing and treating bacterial infections. As a new class of vaccines, killed but metabolically active (KBMA) vaccines provide the immunogenicity of live vaccines and the safety of inactivated vaccines. Herein, a promising strategy is proposed to improve the stability and immunogenicity of KBMA vaccines. KBMA vaccines were produced at low temperature (4 °C), and the bacterial surface was engineered using mesoporous silica nanoparticle (MSN) coating. Compared to vaccines prepared at room temperature, the metabolic activity of KBMA vaccines prepared at 4 °C remarkably improved. Benefiting from the induction of MSNs, the stability of KBMA vaccines was increased and the preservation time was prolonged at 4 °C. Meanwhile, metabolomics analysis showed that the metabolite spectrum of live bacteria changed after photochemical treatment and MSN coating, which interfered with organic acid metabolism pathways, lipid metabolism and biosynthesis of secondary metabolites. Furthermore, the immune response in the mice treated with KBMA/MSN vaccines was similar to that in those treated with live vaccines and stronger than that in those treated with inactivated vaccines. In comparison with the control group, bacteria tissue burdens of KBMA/MSN group were significantly reduced. CD4+ T cells dominated immune responses for the protection of mice. Thus, the current work promotes the application of KBMA vaccines, providing an alternative choice for treating bacterial infections.

The application of bacteria-nanomaterial hybrids in antitumor therapy

Adverse effects and multidrug resistance remain significant obstacles in conventional cancer therapy. Nanomedicines, with their intrinsic properties such as nano-sized dimensions and tunable surface characteristics, have the potential to mitigate the side effects of traditional cancer treatments. While nanomaterials have been widely applied in cancer treatment, challenges such as low targeting efficiency and poor tumor penetration persist. Recent research has shown that anaerobic bacteria exhibit high selectivity for primary tumors and metastatic cancers, offering good safety and superior tumor penetration capabilities. This suggests that combining nanomaterials with bacteria could complement their respective limitations, opening vast potential applications in cancer therapy. The use of bacteria in combination with nanomaterials for anticancer treatments, including chemotherapy, radiotherapy, and photothermal/photodynamic therapy, has contributed to the rapid development of the field of bacterial oncology treatments. This review explores the mechanisms of bacterial tumor targeting and summarizes strategies for synthesizing bacterial-nanomaterial and their application in cancer therapy. The combination of bacterial-nanomaterial hybrids with modern therapeutic approaches represents a promising avenue for future cancer treatment research, with the potential to improve treatment outcomes for cancer patients.

Bacterial derivatives mediated drug delivery in cancer therapy: a new generation strategy

Cancer is measured as a major threat to human life and is a leading cause of death. Millions of cancer patients die every year, although a burgeoning number of researchers have been making tremendous efforts to develop cancer medicine to fight against cancer. Owing to the complexity and heterogeneity of cancer, lack of ability to treat deep tumor tissues, and high toxicity to the normal cells, it complicates the therapy of cancer. However, bacterial derivative-mediated drug delivery has raised the interest of researchers in overcoming the restrictions of conventional cancer chemotherapy. In this review, we show various examples of tumor-targeting bacteria and bacterial derivatives for the delivery of anticancer drugs. This review also describes the advantages and limitations of delivering anticancer treatment drugs under regulated conditions employing these tumor-targeting bacteria and their membrane vesicles. This study highlights the substantial potential for clinical translation of bacterial-based drug carriers, improve their ability to work with other treatment modalities, and provide a more powerful, dependable, and distinctive tumor therapy.

Bacterial nanotechnology as a paradigm in targeted cancer therapeutic delivery and immunotherapy

Cancer, a multifaceted and diverse ailment, presents formidable obstacles to traditional treatment modalities. Nanotechnology presents novel prospects for surmounting these challenges through its capacity to facilitate meticulous and regulated administration of therapeutic agents to malignant cells while concurrently modulating the immune system to combat neoplasms. Bacteria and their derivatives have emerged as highly versatile and multifunctional platforms for cancer nanotherapy within the realm of nanomaterials. This comprehensive review delves into the multifaceted and groundbreaking implementations of bacterial nanotechnology within cancer therapy. This review encompasses four primary facets: the utilization of bacteria as living conveyors of medicinal substances, the employment of bacterial components as agents that stimulate the immune system, the deployment of bacterial vectors as tools for delivering genetic material, and the development of bacteria-derived nano-drugs as intelligent nano-medications. Furthermore, we elucidate the merits and modalities of operation pertaining to these bacterial nano-systems, along with their capacity to synergize with other cutting-edge nanotechnologies, such as CRISPR-Cas systems. Additionally, we offer insightful viewpoints regarding the forthcoming trajectories and prospects within this expanding domain. It is our deduction that bacterial nanotechnology embodies a propitious and innovative paradigm in the realm of cancer therapy, which has the potential to provide numerous advantages and synergistic effects in enhancing the outcomes and quality of life for individuals afflicted with cancer.

Bioinspired and Biomimetic Gene Delivery Systems

Gene therapy that can introduce, counteract, or replace genes possesses great potential to address diseases at their genetic roots. A wide range of technologies, such as RNA interference, genome editing, DNA transformation, and mRNA vaccines, have been extensively investigated to modulate gene expression in an attempt to treat a myriad of diseases. Despite the great promise of gene therapeutics, a series of intracellular and extracellular barriers must be surmounted, including rapid clearance in circulation, insufficient site-specific accumulation, suboptimal cellular internalization, and deficient transfection efficiency. Advances in the delivery systems for gene delivery bring about profound progress in enhancing the bioavailability and biocompatibility of gene therapeutics. Notably, bioinspired and biomimetic gene delivery systems have emerged, which draw inspiration from natural processes and recapitulate the desired traits and functions of viruses, bacteria, exosomes, and eukaryotic cells. The integration of bioinspired and biomimetic designs can overcome biological barriers, improve the pharmacokinetic profile, and efficiently transport gene therapeutics to target cells. As such, these platforms amplify the therapeutic efficacy and reduce side effects, thus expediting the clinical translation of gene therapy. Herein, we summarize the latest advances in designing bioinspired or biomimetic delivery systems, introduce their advantages, and discuss the obstacles to overcome with rational designs.

Synthesis and improved optical, electrical, and dielectric properties of PEO/PVA/CuCo2O4 nanocomposites

This study investigates the development of novel nanocomposite films based on a blend of polyethylene oxide (PEO) and polyvinyl alcohol (PVA) loaded with varying weight percentages of copper cobaltite nanoparticles (CuCo2O4 NPs). The primary objective was to fabricate these nanocomposites using a solution casting technique and explore the influence of CuCo2O4 content on their structural, optical, electrical, and dielectric properties. Spinel-type CuCo2O4 NPs were synthesized via the hydrothermal method and incorporated into the PEO/PVA blend. X-ray diffraction (XRD) analysis revealed the transformation of the polymer matrix towards an amorphous state with increasing CuCo2O4 content. UV-Vis spectroscopy studies demonstrated a decrease in both the direct and indirect band gaps of the nanocomposites, suggesting potential applications in optoelectronic devices. Impedance spectroscopy measurements revealed a significant enhancement in ionic conductivity (three orders of magnitude higher than the pristine blend) for the nanocomposite film containing 1.8 wt% CuCo2O4. The real permittivity (ε') and imaginary permittivity (ε″) of the polymer nanocomposites exhibited a decrease with increasing frequency due to the interplay of various polarization mechanisms. Notably, incorporating 1.8 wt% CuCo2O4 nanoparticles led to a remarkable improvement in energy density compared to the pristine blend. Additionally, a significant decrease in the potential barrier was observed. These findings demonstrate the successful fabrication of PEO/PVA-CuCo2O4 nanocomposite films with enhanced optical, electrical, and dielectric properties. The observed improvements suggest promising applications for these materials in energy storage devices and potentially in optoelectronic devices like light-emitting diodes.

Microbe-material hybrids for therapeutic applications

As natural living substances, microorganisms have emerged as useful resources in medicine for creating microbe-material hybrids ranging from nano to macro dimensions. The engineering of microbe-involved nanomedicine capitalizes on the distinctive physiological attributes of microbes, particularly their intrinsic "living" properties such as hypoxia tendency and oxygen production capabilities. Exploiting these remarkable characteristics in combination with other functional materials or molecules enables synergistic enhancements that hold tremendous promise for improved drug delivery, site-specific therapy, and enhanced monitoring of treatment outcomes, presenting substantial opportunities for amplifying the efficacy of disease treatments. This comprehensive review outlines the microorganisms and microbial derivatives used in biomedicine and their specific advantages for therapeutic application. In addition, we delineate the fundamental strategies and mechanisms employed for constructing microbe-material hybrids. The diverse biomedical applications of the constructed microbe-material hybrids, encompassing bioimaging, anti-tumor, anti-bacteria, anti-inflammation and other diseases therapy are exhaustively illustrated. We also discuss the current challenges and prospects associated with the clinical translation of microbe-material hybrid platforms. Therefore, the unique versatility and potential exhibited by microbe-material hybrids position them as promising candidates for the development of next-generation nanomedicine and biomaterials with unique theranostic properties and functionalities.

Cancer Nanovaccines: Nanomaterials and Clinical Perspectives

Cancer nanovaccines represent a promising frontier in cancer immunotherapy, utilizing nanotechnology to augment traditional vaccine efficacy. This review comprehensively examines the current state-of-the-art in cancer nanovaccine development, elucidating innovative strategies and technologies employed in their design. It explores both preclinical and clinical advancements, emphasizing key studies demonstrating their potential to elicit robust anti-tumor immune responses. The study encompasses various facets, including integrating biomaterial-based nanocarriers for antigen delivery, adjuvant selection, and the impact of nanoscale properties on vaccine performance. Detailed insights into the complex interplay between the tumor microenvironment and nanovaccine responses are provided, highlighting challenges and opportunities in optimizing therapeutic outcomes. Additionally, the study presents a thorough analysis of ongoing clinical trials, presenting a snapshot of the current clinical landscape. By curating the latest scientific findings and clinical developments, this study aims to serve as a comprehensive resource for researchers and clinicians engaged in advancing cancer immunotherapy. Integrating nanotechnology into vaccine design holds immense promise for revolutionizing cancer treatment paradigms, and this review provides a timely update on the evolving landscape of cancer nanovaccines.

Harnessing and Mimicking Bacterial Features to Combat Cancer: From Living Entities to Artificial Mimicking Systems

Bacterial-derived micro-/nanomedicine has garnered considerable attention in anticancer therapy, owing to the unique natural features of bacteria, including specific targeting ability, immunogenic benefits, physicochemical modifiability, and biotechnological editability. Besides, bacterial components have also been explored as promising drug delivery vehicles. Harnessing these bacterial features, cutting-edge physicochemical and biotechnologies have been applied to attenuated tumor-targeting bacteria with unique properties or functions for potent and effective cancer treatment, including strategies of gene-editing and genetic circuits. Further, the advent of bacteria-inspired micro-/nanorobots and mimicking artificial systems has furnished fresh perspectives for formulating strategies for developing highly efficient drug delivery systems. Focusing on the unique natural features and advantages of bacteria, this review delves into advances in bacteria-derived drug delivery systems for anticancer treatment in recent years, which has experienced a process from living entities to artificial mimicking systems. Meanwhile, a summary of relative clinical trials is provided and primary challenges impeding their clinical application are discussed. Furthermore, future directions are suggested for bacteria-derived systems to combat cancer.

Microbes in the tumor microenvironment: New additions to break the tumor immunotherapy dilemma

Immunotherapies currently used in clinical practice are unsatisfactory in terms of therapeutic response and toxic side effects, and therefore new immunotherapies need to be explored. Intratumoral microbiota (ITM) exists in the tumor environment (TME) and reacts with its components. On the one hand, ITM promotes antigen delivery to tumor cells or provides cross-antigens to promote immune cells to attack tumors. On the other hand, ITM affects the activity of immune cells and stromal cells. We also summarize the dialog pathways by which ITM crosstalks with components within the TME, particularly the interferon pathway. This interaction between ITM and TME provides new ideas for tumor immunotherapy. By analyzing the bidirectional role of ITM in TME and combining it with its experimental and clinical status, we summarized the adjuvant role of ITM in immunotherapy. We explored the potential applications of using ITM as tumor immunotherapy, such as a healthy diet, fecal transplantation, targeted ITM, antibiotics, and probiotics, to provide a new perspective on the use of ITM in tumor immunotherapy.

Exploiting bacteria for cancer immunotherapy

Immunotherapy has revolutionized the treatment of cancer but continues to be constrained by limited response rates, acquired resistance, toxicities and high costs, which necessitates the development of new, innovative strategies. The discovery of a connection between the human microbiota and cancer dates back 4,000 years, when local infection was observed to result in tumour eradication in some individuals. However, the true oncological relevance of the intratumoural microbiota was not recognized until the turn of the twentieth century. The intratumoural microbiota can have pivotal roles in both the pathogenesis and treatment of cancer. In particular, intratumoural bacteria can either promote or inhibit cancer growth via remodelling of the tumour microenvironment. Over the past two decades, remarkable progress has been made preclinically in engineering bacteria as agents for cancer immunotherapy; some of these bacterial products have successfully reached the clinical stages of development. In this Review, we discuss the characteristics of intratumoural bacteria and their intricate interactions with the tumour microenvironment. We also describe the many strategies used to engineer bacteria for use in the treatment of cancer, summarizing contemporary data from completed and ongoing clinical trials. The work described herein highlights the potential of bacteria to transform the landscape of cancer therapy, bridging ancient wisdom with modern scientific innovation.

Nucleic acid cancer vaccines targeting tumor related angiogenesis. Could mRNA vaccines constitute a game changer?

Tumor related angiogenesis is an attractive target in cancer therapeutic research due to its crucial role in tumor growth, invasion, and metastasis. Different agents were developed aiming to inhibit this process; however they had limited success. Cancer vaccines could be a promising tool in anti-cancer/anti-angiogenic therapy. Cancer vaccines aim to initiate an immune response against cancer cells upon presentation of tumor antigens which hopefully will result in the eradication of disease and prevention of its recurrence by inducing an efficient and long-lasting immune response. Different vaccine constructs have been developed to achieve this and they could include either protein-based or nucleic acid-based vaccines. Nucleic acid vaccines are simple and relatively easy to produce, with high efficiency and safety, thus prompting a high interest in the field. Different DNA vaccines have been developed to target crucial regulators of tumor angiogenesis. Most of them were successful in pre-clinical studies, mostly when used in combination with other therapeutics, but had limited success in the clinic. Apparently, different tumor evasion mechanisms and reduced immunogenicity still limit the potential of these vaccines and there is plenty of room for improvement. Nowadays, mRNA cancer vaccines are making remarkable progress due to improvements in the manufacturing technology and represent a powerful potential alternative. Apart from their efficiency, mRNA vaccines are simple and cheap to produce, can encompass multiple targets simultaneously, and can be quickly transferred from bench to bedside. mRNA vaccines have already accomplished amazing results in cancer clinical trials, thus ensuring a bright future in the field, although no anti-angiogenic mRNA vaccines have been described yet. This review aims to describe recent advances in anti-angiogenic DNA vaccine therapy and to provide perspectives for use of revolutionary approaches such are mRNA vaccines for anti-angiogenic treatments.

Novel strategies for modulating the gut microbiome for cancer therapy

Recent advancements in genomics, transcriptomics, and metabolomics have significantly advanced our understanding of the human gut microbiome and its impact on the efficacy and toxicity of anti-cancer therapeutics, including chemotherapy, immunotherapy, and radiotherapy. In particular, prebiotics, probiotics, and postbiotics are recognized for their unique properties in modulating the gut microbiota, maintaining the intestinal barrier, and regulating immune cells, thus emerging as new cancer treatment modalities. However, clinical translation of microbiome-based therapy is still in its early stages, facing challenges to overcome physicochemical and biological barriers of the gastrointestinal tract, enhance target-specific delivery, and improve drug bioavailability. This review aims to highlight the impact of prebiotics, probiotics, and postbiotics on the gut microbiome and their efficacy as cancer treatment modalities. Additionally, we summarize recent innovative engineering strategies designed to overcome challenges associated with oral administration of anti-cancer treatments. Moreover, we will explore the potential benefits of engineered gut microbiome-modulating approaches in ameliorating the side effects of immunotherapy and chemotherapy.

Nanomaterial-assisted oncolytic bacteria in solid tumor diagnosis and therapeutics

Cancer presents a formidable challenge in modern medicine due to the intratumoral heterogeneity and the dynamic microenvironmental niche. Natural or genetically engineered oncolytic bacteria have always been hailed by scientists for their intrinsic tumor-targeting and oncolytic capacities. However, the immunogenicity and low toxicity inevitably constrain their application in clinical practice. When nanomaterials, characterized by distinctive physicochemical properties, are integrated with oncolytic bacteria, they achieve mutually complementary advantages and construct efficient and safe nanobiohybrids. In this review, we initially analyze the merits and drawbacks of conventional tumor therapeutic approaches, followed by a detailed examination of the precise oncolysis mechanisms employed by oncolytic bacteria. Subsequently, we focus on harnessing nanomaterial-assisted oncolytic bacteria (NAOB) to augment the effectiveness of tumor therapy and utilizing them as nanotheranostic agents for imaging-guided tumor treatment. Finally, by summarizing and analyzing the current deficiencies of NAOB, this review provides some innovative directions for developing nanobiohybrids, intending to infuse novel research concepts into the realm of solid tumor therapy.

Breaking barriers in cancer treatment: nanobiohybrids empowered by modified bacteria and vesicles

Cancer, the leading global cause of mortality, poses a formidable challenge for treatment. The effectiveness of cancer therapies, ranging from chemotherapy to immunotherapy, relies on the precise delivery of therapeutic agents to tumor tissues. Nanobiohybrids, resulting from the fusion of bacteria with nanomaterials, constitute a promising delivery system. Nanobiohybrids offer several advantages, including the ability to target tumors, genetic engineering capabilities, programmed product creation, and the potential for multimodal treatment. Recent advances in targeted tumor treatments have leveraged bacteria-based nanobiohybrids. Here, we outline the progress in cancer treatment using nanobiohybrids. Our focus is particularly on various therapeutic approaches within the context of nanobiohybrid systems, where bacteria are integrated with nanomaterials to combat cancer. It has been demonstrated that bacteria-based nanobiohybrids present a robust and effective method for tumor theranostics.

Synergistic interaction of nanoparticles and probiotic delivery: A review

Nanotechnology is an expanding and new technology that prompts production with nanoparticle-based (1-100 nm) organic and inorganic materials. Such a tool has an imperative function in different sectors like bioengineering, pharmaceuticals, electronics, energy, nuclear energy, and fuel, and its applications are helpful for human, animal, plant, and environmental health. In exacting, the nanoparticles are synthesized by top-down and bottom-up approaches through different techniques such as chemical, physical, and biological progress. The characterization is vital and the confirmation of nanoparticle traits is done by various instrumentation analyses like UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy, X-ray diffraction, atomic force microscopy, annular dark-field imaging, and intracranial pressure. In addition, probiotics are friendly microbes which while administered in sufficient quantity confer health advantages to the host. Characterization investigation is much more significant to the identification of good probiotics. Similarly, haemolytic activity, acid and bile salt tolerance, autoaggregation, antimicrobial compound production, inhibition of pathogens, enhance the immune system, and more health-beneficial effects on the host. The synergistic effects of nanoparticles and probiotics combined delivery applications are still limited to food, feed, and biomedical applications. However, the mechanisms by which they interact with the immune system and gut microbiota in humans and animals are largely unclear. This review discusses current research advancements to fulfil research gaps and promote the successful improvement of human and animal health.

Synergistic Brilliance: Engineered Bacteria and Nanomedicine Unite in Cancer Therapy

Engineered bacteria are widely used in cancer treatment because live facultative/obligate anaerobes can selectively proliferate at tumor sites and reach hypoxic regions, thereby causing nutritional competition, enhancing immune responses, and producing anticancer microbial agents in situ to suppress tumor growth. Despite the unique advantages of bacteria-based cancer biotherapy, the insufficient treatment efficiency limits its application in the complete ablation of malignant tumors. The combination of nanomedicine and engineered bacteria has attracted increasing attention owing to their striking synergistic effects in cancer treatment. Engineered bacteria that function as natural vehicles can effectively deliver nanomedicines to tumor sites. Moreover, bacteria provide an opportunity to enhance nanomedicines by modulating the TME and producing substrates to support nanomedicine-mediated anticancer reactions. Nanomedicine exhibits excellent optical, magnetic, acoustic, and catalytic properties, and plays an important role in promoting bacteria-mediated biotherapies. The synergistic anticancer effects of engineered bacteria and nanomedicines in cancer therapy are comprehensively summarized in this review. Attention is paid not only to the fabrication of nanobiohybrid composites, but also to the interpromotion mechanism between engineered bacteria and nanomedicine in cancer therapy. Additionally, recent advances in engineered bacteria-synergized multimodal cancer therapies are highlighted.

An oral bioactive chitosan-decorated doxorubicin nanoparticles/bacteria bioconjugates enhance chemotherapy efficacy in an in-situ breast cancer model

Breast cancer is the second leading cause of cancer-related deaths among women worldwide. Despite significant advancements in chemotherapy, its effectiveness is often limited by poor drug distribution and systemic toxicity caused by the weak targeting ability of conventional therapeutic agents. The hypoxic tumor microenvironment (TME) also plays a vital role in treatment outcomes. Oral anticancer therapeutic agents have gained popularity and show promising results due to their ease of repeated administration. This study introduces autopilot biohybrids (Bif@BDC-NPs) for the effective delivery of doxorubicin (DOX) to the tumor site. This hybrid combines albumin-encapsulated DOX nanoparticles (BD-NPs) coated with chitosan (CS) for breast cancer chemotherapy, along with anaerobic Bifidobacterium infantis (B. infantis, Bif) serving as self-propelled motors. Due to Bif's specific anaerobic properties, Bif@BDC-NPs precisely anchor hypoxic regions of tumor tissue and significantly increase drug accumulation at the tumor site, thereby promoting tumor cell death. In an in-situ mouse breast cancer model, Bif@BDC-NPs achieved 94 % tumor inhibition, significantly prolonging the median survival of mice to 62 days, and reducing the toxic side effects of DOX. Therefore, the new bacteria-driven oral drug delivery system, Bif@BDC-NPs, overcomes multiple physiological barriers and holds great potential for the precise treatment of solid tumors.

Nanoparticle/Engineered Bacteria Based Triple-Strategy Delivery System for Enhanced Hepatocellular Carcinoma Cancer Therapy

Background

New treatment modalities for hepatocellular carcinoma (HCC) are desperately critically needed, given the lack of specificity, severe side effects, and drug resistance with single chemotherapy. Engineered bacteria can target and accumulate in tumor tissues, induce an immune response, and act as drug delivery vehicles. However, conventional bacterial therapy has limitations, such as drug loading capacity and difficult cargo release, resulting in inadequate therapeutic outcomes. Synthetic biotechnology can enhance the precision and efficacy of bacteria-based delivery systems. This enables the selective release of therapeutic payloads in vivo.

Methods

In this study, we constructed a non-pathogenic Escherichia coli (E. coli) with a synchronized lysis circuit as both a drug/gene delivery vehicle and an in-situ (hepatitis B surface antigen) Ag (ASEc) producer. Polyethylene glycol (CHO-PEG2000-CHO)-poly(ethyleneimine) (PEI25k)-citraconic anhydride (CA)-doxorubicin (DOX) nanoparticles loaded with plasmid encoded human sulfatase 1 (hsulf-1) enzyme (PNPs) were anchored on the surface of ASEc (ASEc@PNPs). The composites were synthesized and characterized. The in vitro and in vivo anti-tumor effect of ASEc@PNPs was tested in HepG2 cell lines and a mouse subcutaneous tumor model.

Results

The results demonstrated that upon intravenous injection into tumor-bearing mice, ASEc can actively target and colonise tumor sites. The lytic genes to achieve blast and concentrated release of Ag significantly increased cytokine secretion and the intratumoral infiltration of CD4/CD8+T cells, initiated a specific immune response. Simultaneously, the PNPs system releases hsulf-1 and DOX into the tumor cell resulting in rapid tumor regression and metastasis prevention.

Conclusion

The novel drug delivery system significantly suppressed HCC in vivo with reduced side effects, indicating a potential strategy for clinical HCC therapy.

Self-propelling bacteria-based magnetic nanoparticles (BacMags) for targeted magnetic hyperthermia therapy against hypoxic tumors

Magnetic hyperthermia-based cancer therapy (MHCT) holds great promise as a non-invasive approach utilizing heat generated by an alternating magnetic field for effective cancer treatment. For an efficacious therapeutic response, it is crucial to deliver therapeutic agents selectively at the depth of tumors. In this study, we present a new strategy using the naturally occurring tumor-colonizing bacteria Escherichia coli (E. coli) as a carrier to deliver magnetic nanoparticles to hypoxic tumor cores for effective MHCT. Self-propelling delivery agents, "nano-bacteriomagnets" (BacMags), were developed by incorporating anisotropic magnetic nanocubes into E. coli which demonstrated significantly improved hyperthermic performance, leading to an impressive 85% cell death in pancreatic cancer. The in vivo anti-cancer response was validated in a syngeneic xenograft model with a 50% tumor inhibition rate within 20 days and a complete tumor regression within 30 days. This proof-of-concept study demonstrates the potential of utilizing anaerobic bacteria for the delivery of magnetic nanocarriers as a smart therapeutic approach for enhanced MHCT.

Convergence of Nanotechnology and Bacteriotherapy for Biomedical Applications

Bacteria have distinctive properties that make them ideal for biomedical applications. They can self-propel, sense their surroundings, and be externally detected. Using bacteria as medical therapeutic agents or delivery platforms opens new possibilities for advanced diagnosis and therapies. Nano-drug delivery platforms have numerous advantages over traditional ones, such as high loading capacity, controlled drug release, and adaptable functionalities. Combining bacteria and nanotechnologies to create therapeutic agents or delivery platforms has gained increasing attention in recent years and shows promise for improved diagnosis and treatment of diseases. In this review, design principles of integrating nanoparticles with bacteria, bacteria-derived nano-sized vesicles, and their applications and future in advanced diagnosis and therapeutics are summarized.

Poly(ethylenimine)-Cyclodextrin-Based Cationic Polymer Mediated HIF-1α Gene Delivery for Hindlimb Ischemia Treatment

Hindlimb ischemia is a common disease worldwide featured by the sudden decrease in limb perfusion, which usually causes a potential threat to limb viability and even amputation or death. Revascularization has been defined as the gold-standard therapy for hindlimb ischemia. Considering that vascular injury recovery requires cellular adaptation to the hypoxia, hypoxia-inducible factor 1 α (HIF-1α) is a potential gene for tissue restoration and angiogenesis. In this manuscript, effective gene delivery vector PEI-β-CD (PC) was reported for the first application in the hindlimb ischemia treatment to deliver HIF-1α plasmid in vitro and in vivo. Our in vitro finding demonstrated that PC/HIF-1α-pDNA could be successfully entered into the cells and mediated efficient gene transfection with good biocompatibility. More importantly, under hypoxic conditions, PC/HIF-1α-pDNA could up-regulate the HUEVC cell viability. In addition, the mRNA levels of VEGF, Ang-1, and PDGF were upregulated, and transcriptome results also demonstrated that the cell-related function of response to hypoxia was enhanced. The therapeutic effect of PC/HIF-1α-pDNA was further estimated in a murine acute hindlimb ischemia model, which demonstrated that intramuscular injection of PC/HIF-1α-pDNA resulted in significantly increased blood perfusion and alleviation in tissue damage, such as tissue fibrosis and inflammation. The results provide a rationale that HIF-1α-mediated gene therapy might be a practical strategy for the treatment of limb ischemia.

The Current and Promising Oral Delivery Methods for Protein- and Peptide-Based Drugs

Drugs based on peptides and proteins (PPs) have been widely used in medicine, beginning with insulin therapy in patients with diabetes mellitus over a century ago. Although the oral route of drug administration is the preferred one by the vast majority of patients and improves compliance, medications of this kind due to their specific chemical structure are typically delivered parenterally, which ensures optimal bioavailability. In order to overcome issues connected with oral absorption of PPs such as their instability depending on digestive enzymes and pH changes in the gastrointestinal (GI) system on the one hand, but also their limited permeability across physiological barriers (mucus and epithelium) on the other hand, scientists have been strenuously searching for novel delivery methods enabling peptide and protein drugs (PPDs) to be administered enterally. These include utilization of different nanoparticles, transport channels, substances enhancing permeation, chemical modifications, hydrogels, microneedles, microemulsion, proteolytic enzyme inhibitors, and cell-penetrating peptides, all of which are extensively discussed in this review. Furthermore, this article highlights oral PP therapeutics both previously used in therapy and currently available on the medical market.

Functional Nucleic Acid-Based Immunomodulation for T Cell-Mediated Cancer Therapy

T cell-mediated immunity plays a pivotal role in cancer immunotherapy. The anticancer actions of T cells are coordinated by a sequence of biological processes, including the capture and presentation of antigens by antigen-presenting cells (APCs), the activation of T cells by APCs, and the subsequent killing of cancer cells by activated T cells. However, cancer cells have various means to evade immune responses. Meanwhile, these vulnerabilities provide potential targets for cancer treatments. Functional nucleic acids (FNAs) make up a class of synthetic nucleic acids with specific biological functions. With their diverse functionality, good biocompatibility, and high programmability, FNAs have attracted widespread interest in cancer immunotherapy. This Review focuses on recent research progress in employing FNAs as molecular tools for T cell-mediated cancer immunotherapy, including corresponding challenges and prospects.

Engineered Probiotic-Based Personalized Cancer Vaccine Potentiates Antitumor Immunity through Initiating Trained Immunity

Cancer vaccines hold great potential for clinical cancer treatment by eliciting T cell-mediated immunity. However, the limited numbers of antigen-presenting cells (APCs) at the injection sites, the insufficient tumor antigen phagocytosis by APCs, and the presence of a strong tumor immunosuppressive microenvironment severely compromise the efficacy of cancer vaccines. Trained innate immunity may promote tumor antigen-specific adaptive immunity. Here, a personalized cancer vaccine is developed by engineering the inactivated probiotic Escherichia coli Nissle 1917 to load tumor antigens and β-glucan, a trained immunity inducer. After subcutaneous injection, the cancer vaccine delivering model antigen OVA (BG/OVA@EcN) is highly accumulated and phagocytosed by macrophages at the injection sites to induce trained immunity. The trained macrophages may recruit dendritic cells (DCs) to facilitate BG/OVA@EcN phagocytosis and the subsequent DC maturation and T cell activation. In addition, BG/OVA@EcN remarkably enhances the circulating trained monocytes/macrophages, promoting differentiation into M1-like macrophages in tumor tissues. BG/OVA@EcN generates strong prophylactic and therapeutic efficacy to inhibit tumor growth by inducing potent adaptive antitumor immunity and long-term immune memory. Importantly, the cancer vaccine delivering autologous tumor antigens efficiently prevents postoperative tumor recurrence. This platform offers a facile translatable strategy to efficiently integrate trained immunity and adaptive immunity for personalized cancer immunotherapy.

Natural Biopolymer-Based Delivery of CRISPR/Cas9 for Cancer Treatment

Over the last decade, the clustered, regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has become the most promising gene editing tool and is broadly utilized to manipulate the gene for disease treatment, especially for cancer, which involves multiple genetic alterations. Typically, CRISPR/Cas9 machinery is delivered in one of three forms: DNA, mRNA, or ribonucleoprotein. However, the lack of efficient delivery systems for these macromolecules confined the clinical breakthrough of this technique. Therefore, a variety of nanomaterials have been fabricated to improve the stability and delivery efficiency of the CRISPR/Cas9 system. In this context, the natural biopolymer-based carrier is a particularly promising platform for CRISPR/Cas9 delivery due to its great stability, low toxicity, excellent biocompatibility, and biodegradability. Here, we focus on the advances of natural biopolymer-based materials for CRISPR/Cas9 delivery in the cancer field and discuss the challenges for their clinical translation.

Oral Administration of Cancer Vaccines: Challenges and Future Perspectives

Cancer vaccines, a burgeoning strategy in cancer treatment, are exploring innovative administration routes to enhance patient and medical staff experiences, as well as immunological outcomes. Among these, oral administration has surfaced as a particularly noteworthy approach, which is attributed to its capacity to ignite both humoral and cellular immune responses at systemic and mucosal tiers, thereby potentially bolstering vaccine efficacy comprehensively and durably. Notwithstanding this, the deployment of vaccines through the oral route in a clinical context is impeded by multifaceted challenges, predominantly stemming from the intricacy of orchestrating effective oral immunogenicity and necessitating strategic navigation through gastrointestinal barriers. Based on the immunogenicity of the gastrointestinal tract, this review critically analyses the challenges and recent advances and provides insights into the future development of oral cancer vaccines.

Hypoxia-targeted and spatial-selective tumor suppression by near infrared nanoantenna sensitized engineered bacteria

It is an active research area in the development of engineered bacteria to address the bottleneck issue of hypoxic tumors, which otherwisely possess resistance to chemotherapies, radiotherapies, and photodynamic therapies. Here we report a new method to ablate hypoxic tumors with NIR-nanoantenna sensitized engineered bacteria (NASEB) in a highly effective and dual selective manner. It features engineered E. coli MG1655 (EB) with coatings of lanthanide upconversion nanoparticles (UCNPs) as external antennas on bacterial surface (MG1655/HlyE-sfGFP@UCNP@PEG), enabling NIR laser-switchable generation/secretion of HlyE perforin to kill cancer cells. We have demonstrated that NASEB enrichment on hypoxic tumor sites via their innate chemotactic tendency, in assistance of localized NIR laser irradiation, can suppress tumors with improved efficacy and selectivity, thus minimizing potential side effects in cancer treatment. The NIR-responsive nanoantenna sensitized switching in engineering bacteria is distinct from the previous reports, promising conceptually new development of therapeutics against hypoxic tumors. STATEMENT OF SIGNIFICANCE: Tumor hypoxia exacerbates tumor progression, but also reduces the efficacy of conventional chemotherapies, radiotherapies, or photodynamic therapies. Here we develop near infrared Nano Antenna Sensitized Engineered Bacteria (NASEB) to treat hypoxic tumors. NASEB can accumulate and proliferate on hypoxic tumor sites via their innate chemotactic tendency. After receiving NIR laser signals, the upconversion nanoparticles on NASEB surface as antennas can transduce them to blue light for activation of HlyE perforin in the protein factory of EB. Our method features dual selectivity on the tumor sites, contributed by hypoxic tumor homing of anaerobic bacteria and spatial confinement through selective NIR laser irradiation. The concept of NASEB promises to address the challenges of tumor hypoxia for cancer therapies.

Surface-modified bacteria: synthesis, functionalization and biomedical applications

The past decade has witnessed a great leap forward in bacteria-based living agents, including imageable probes, diagnostic reagents, and therapeutics, by virtue of their unique characteristics, such as genetic manipulation, rapid proliferation, colonization capability, and disease site targeting specificity. However, successful translation of bacterial bioagents to clinical applications remains challenging, due largely to their inherent susceptibility to environmental insults, unavoidable toxic side effects, and limited accumulation at the sites of interest. Cell surface components, which play critical roles in shaping bacterial behaviors, provide an opportunity to chemically modify bacteria and introduce different exogenous functions that are naturally unachievable. With the help of surface modification, a wide range of functionalized bacteria have been prepared over the past years and exhibit great potential in various biomedical applications. In this article, we mainly review the synthesis, functionalization, and biomedical applications of surface-modified bacteria. We first introduce the approaches of chemical modification based on the bacterial surface structure and then highlight several advanced functions achieved by modifying specific components on the surface. We also summarize the advantages as well as limitations of surface chemically modified bacteria in the applications of bioimaging, diagnosis, and therapy and further discuss the current challenges and possible solutions in the future. This work will inspire innovative design thinking for the development of chemical strategies for preparing next-generation biomedical bacterial agents.

Organic functional substance engineered living materials for biomedical applications

Modifying living materials with organic functional substances (OFS) is a convenient and effective strategy to control and monitor the transport, engraftment, and secretion processes in living organisms. OFSs, including small organic molecules and organic polymers, own the merit of design flexibility, satisfying performance, and excellent biocompatibility, which allow for living materials functionalization to realize real-time sensing, controlled drug release, enhanced biocompatibility, accurate diagnosis, and precise treatment. In this review, we discuss the different principles of OFS modification on living materials and demonstrate the applications of engineered living materials in health monitoring, drug delivery, wound healing, and tissue regeneration.

Deep Tumor Penetration of CRISPR-Cas System for Photothermal-Sensitized Immunotherapy via Probiotics

Since central cells are more malignant and aggressive in solid tumors, improving penetration of therapeutic agents and activating immunity in tumor centers exhibit great potential in cancer therapies. Here, polydopamine-coated Escherichia coli Nissle 1917 (EcN) bearing CRISPR-Cas9 plasmid-loaded liposomes (Lipo-P) are applied for enhanced immunotherapy in deep tumors through activation of innate and adaptive immunity simultaneously. After accumulation in the tumor center through hypoxia targeting, Lipo-P could be detached under the reduction of reactive oxygen species (ROS)-responsive linkers, lowering the thermal resistance of cancer cells via Hsp90α depletion. Owing to that, heating induced by polydopamine upon near-infrared irradiation could achieve effective tumor ablation. Furthermore, mild photothermal therapy induces immunogenic cell death, as bacterial infections in tumor tissues trigger innate immunity. This bacteria-assisted approach provides a promising photothermal-sensitized immunotherapy in deep tumors.

Bacterial Drug Delivery Systems for Cancer Therapy: "Why" and "How"

Cancer is one of the major diseases that endanger human health. However, the use of anticancer drugs is accompanied by a series of side effects. Suitable drug delivery systems can reduce the toxic side effects of drugs and enhance the bioavailability of drugs, among which targeted drug delivery systems are the main development direction of anticancer drug delivery systems. Bacteria is a novel drug delivery system that has shown great potential in cancer therapy because of its tumor-targeting, oncolytic, and immunomodulatory properties. In this review, we systematically describe the reasons why bacteria are suitable carriers of anticancer drugs and the mechanisms by which these advantages arise. Secondly, we outline strategies on how to load drugs onto bacterial carriers. These drug-loading strategies include surface modification and internal modification of bacteria. We focus on the drug-loading strategy because appropriate strategies play a key role in ensuring the stability of the delivery system and improving drug efficacy. Lastly, we also describe the current state of bacterial clinical trials and discuss current challenges. This review summarizes the advantages and various drug-loading strategies of bacteria for cancer therapy and will contribute to the development of bacterial drug delivery systems.

Development of CRISPR/Cas Delivery Systems for In Vivo Precision Genome Editing

ConspectusClustered, regularly interspaced, short palindromic repeat (CRISPR)/associated protein 9 (CRISPR/Cas9) is emerging as a powerful genome-editing tool, enabling precise and targeted modifications of virtually any genomic sequence in living cells. These technologies have potential therapeutic applications for cancers, metabolic diseases, and genetic disorders. However, several major challenges hinder the full realization of their potential. Specifically, CRISPR-Cas9 gene editors, whether delivered as plasmid DNA, mRNA/sgRNA, or ribonucleoprotein (RNP), exhibit poor membrane permeability, restricting their access to the intracellular genome, where the editing occurs. Additionally, these editors lack tissue or organ specificity, raising concerns about off-target editing at the tissue level that causes unwanted genotoxicity. Though a range of delivery carriers has been developed to deliver Cas9 editors, their effectiveness is often limited by a number of barriers at both the extracellular and intracellular levels. Moreover, the prolonged activity of Cas9 increases the risk of off-target editing at the genomic level. Therefore, it is crucial to develop efficient delivery vectors, along with molecular switches to safely regulate Cas9 activity.In this Account, we summarize our recent achievements in developing different types of materials that can efficiently deliver the plasmid DNA encoding Cas9 protein and single-guide RNA (sgRNA), or Cas9 RNP into cells to highlight the design considerations of carriers for safe and efficient delivery in vitro and in vivo. After elucidating the chemical and physical factors that are responsible for encapsulating and delivering these biomacromolecules, we further elucidate how we design the biodegradable polymeric carriers using dynamic disulfide chemistry, emphasize their safe and efficient delivery features for genome-editing biomacromolecules, and also introduce the integration of the intracellular delivery of genome-editing biomacromolecules with microneedle-based transdermal delivery to promote therapeutic genome editing for inflammatory skin disorders. Finally, we review how we exploit optical, chemical, and genetic switches to control the Cas9 activity in conjunction with targeted delivery to address the spatiotemporal specificity of gene editing in vivo and demonstrate their precision therapy against cancer and colitis treatment as proof-of-concept examples. In the final part, we will summarize the progress we have made and propose the future directions that may impact the field based on our own research outcomes.