Aptamer-assisted tumor localization of bacteria for enhanced biotherapy

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.

A virus-inspired RNA mimicry approach for effective cancer immunotherapy

Current cancer treatments, including chemotherapy, surgery, and radiation, often present significant challenges such as severe side effects, drug resistance, and damage to healthy tissues. To address these issues, we introduce a virus-inspired RNA mimicry approach, specifically through the development of uridine-rich nanoparticles (UNPs) synthesized using the rolling circle transcription (RCT) technique. These UNPs are designed to mimic the poly-U tail sequences of viral RNA, effectively engaging RIG-I-like receptors (RLRs) such as MDA5 and LGP2 in cancer cells. Activation of these receptors leads to the upregulation of pro-inflammatory cytokines and the initiation of apoptosis, resulting in targeted cancer cell death. Importantly, this strategy overcomes the limitations of traditional therapies and enhances the effectiveness of existing RIG-I stimulators, such as poly(I:C), which has often exhibited toxicity in clinical settings due to delivery methods. Our in vivo studies further demonstrate the ability of UNPs to significantly reduce tumor growth without adverse effects, highlighting their potential as a novel and effective approach in cancer immunotherapy. This approach offers new therapeutic strategies that leverage the body's innate antiviral mechanisms for cancer treatment.

Coupling Probiotics with CaO2 Nanoparticle-Loaded CoFeCe-LDH Nanosheets to Remodel the Tumor Microenvironment for Precise Chemodynamic Therapy

Chemodynamic therapy (CDT) has become an emerging cancer treatment strategy with advantages of tumor-specificity, high selectivity, and low systemic toxicity. However, it usually suffers from low therapeutic efficacy. This is caused by low hydroxyl radical (·OH) yield arising because of the relatively high pH, overexpressed glutathione, and low H2O2 concentration in the tumor microenvironment (TME). Herein, a probiotic metabolism-initiated pH reduction and H2O2 supply-enhanced CDT strategy is reported to eradicate tumors by generating ·OH, in which Lactobacillus acidophilus is coupled with CoFeCe-layered double hydroxide nanosheets loaded with CaO2 nanoparticles (NPs) as a chemodynamic platform for high-efficiency CDT (CaO2/LDH@L. acidophilus). Owing to the hypoxia tropism of L. acidophilus, CaO2/LDH@L. acidophilus exhibits increased accumulation at tumor sites compared with the CaO2/LDH. The CaO2 NPs loaded on CoFeCe-LDH nanosheets are decomposed into H2O2 in the TME. L. acidophilus metabolite-induced pH reduction (<5.5) and CaO2-mediated in situ H2O2 generation synergistically boost ·OH generation activity of the CoFeCe-LDH nanosheets, effectively damaging cancer cells and ablating tumors with a tumor inhibition rate of 96.4%, 2.32-fold higher than that of CaO2/LDH. This work demonstrates that probiotics can function as a tumor-targeting platform to remodel the TME and amplify ROS generation for highly efficient and precise CDT.

Time-Responsive Activity of Engineered Bacteria for Local Sterilization and Biofilm Removal in Periodontitis

Periodontitis is a highly prevalent and common condition in people of all ages, however, existing drugs to treat periodontitis have difficulty penetrating complex biofilms. Here, we report a biofilm-penetrating probiotic hybrid strategy for the treatment of periodontitis. It consists of therapeutic probiotics of E. coli Nissle 1917, which can produce antimicrobial peptides and hydrogen, and is coated with D-amino acids that can penetrate biofilms. After the fusion of D-amino acids with the biofilm, EcN entered the plaque biofilm and produced antimicrobial peptides to kill porphyromonas gingivalis and eliminate periodontitis under the action of hydrogen. The efficacy of EcN@DA-D in biofilm penetration and treatment of periodontitis was demonstrated in a rat model of periodontitis. In addition, the clinical combination to construct a rat periodontitis model by using clinical tissue has a significant therapeutic effect. In conclusion, EcN@DA-D offers a promising topical treatment for periodontitis without developing detectable pathogen resistance and side effects.

Iron-Tannin Coating Reduces Clearance and Increases Tumor Colonization of Systemically Delivered Bacteria

Engineered bacteria offer a novel approach to targeted cancer therapy, but challenges remain in delivering enough bacteria safely for effective treatment. Previous efforts have used either a native or synthetic coating to achieve better control over the half-life of bacteria in the body but have limitations in delivery or versatility. In this work, we optimized and evaluated a synthetic coating for probiotic Escherichia coli Nissle 1917 to increase its half-life in blood and thereby increase the bioavailability of intravenous doses of bacteria to colonize and treat tumors. Using a simple one-pot chemical process, we coated bacteria with iron and tannic acid (FeTA) to form a temporary adhesive protective coating surrounding the bacterial cell surface. The iron to tannic acid ratio of the coating was optimized for intravenous use, and FeTA-coated bacteria of several different genetic backgrounds showed 15-fold higher survival in blood survival assays for up to 4 hours. We found that the FeTA coating reduced both complement-mediated bacterial killing and phagocyte-mediated bacterial killing in vitro. As a result, systemic delivery of attenuated bacteria had up to 60% colonization efficiency of FeTA-coated bacteria in an orthotopic breast cancer mouse model compared to 10% for the non-coated control, all the while maintaining a two-fold decrease in weight loss of attenuated bacteria compared to wild-type. Altogether, we show that an optimized FeTA coating significantly extends the half-life and colonization efficiency of engineered bacteria, overcoming a key limitation of their application in cancer therapy.

Surface nanocoating of bacteria as a versatile platform to develop living therapeutics

Bacteria have been extensively utilized as living therapeutics for disease treatment due to their unique characteristics, such as genetic manipulability, rapid proliferation and specificity to target disease sites. Various in vivo insults can, however, decrease the vitality of dosed bacteria, leading to low overall bioavailability. Additionally, the innate antigens on the bacterial surface and the released toxins and metabolites may cause undesired safety issues. These limitations inevitably result in inadequate treatment outcomes, thereby hindering the clinical transformation of living bacterial therapeutics. Recently, we have developed a versatile platform to prepare advanced living bacterial therapeutics by nanocoating bacteria individually via either chemical decoration or physical encapsulation, which can improve bioavailability and reduce side effects for enhanced microbial therapy. Here we use interfacial self-assembly to prepare lipid membrane-coated bacteria (LCB), exhibiting increased resistance against a variety of harsh environmental conditions owing to the nanocoating's protective capability. Meanwhile, we apply mechanical extrusion to generate cell membrane-coated bacteria (CMCB), displaying improved biocompatibility owing to the nanocoating's shielding effect. We describe their detailed preparation procedures and demonstrate the expected functions of the coated bacteria. We also show that following oral delivery and intravenous injection in mouse models, LCB and CMCB present appealing potential for treating colitis and tumors, respectively. Compared with bioengineering that lacks versatile molecular tools for heterogeneous expression, the surface nanocoating technique is convenient to introduce functional components without restriction on bacterial strain types. Excluding bacterial culture, the fabrication of LCB takes ~2 h, while the preparation of CMCB takes ~5 h.

Coating Dormant Collagenase-Producing Bacteria with Metal-Anesthetic Networks for Precision Tumor Therapy

Tumor malignancy highly depends on the stiffness of tumor matrix, which mainly consists of collagen. Despite the destruction of tumor matrix is conducive to tumor therapy, it causes the risk of tumor metastasis. Here, metal-anesthetic network-coated dormant collagenase-producing Clostridium is constructed to simultaneously destruct tumor matrix and inhibit tumor metastasis. By metal-phenolic complexation and π-π stacking interactions, a Fe3+-propofol network is formed on bacterial surface. Coated dormant Clostridium can selectively germinate and rapidly proliferate in tumor sites due to the ability of carried Fe3+ ions to promote bacterial multiplication. Intratumoral colonization of Clostridium produces sufficient collagenases to degrade tumor collagen mesh and the loaded propofol restrains tumor metastasis by inhibiting tumor cell migration and invasion. Meanwhile, the delivered Fe3+ ions are reduced to the Fe2+ form by intracellular glutathione, thereby inducing potent Fenton reaction to trigger lipid peroxidation and ultimate ferroptosis of tumor cells. In addition to a satisfactory safety, a single intratumoral injection of coated dormant Clostridium not only effectively retards the growth of established large primary tumors, but also significantly suppresses distal lung metastasis in two different orthotopic tumor models. This work proposes a strategy to develop advanced therapeutics for malignant tumor treatment and metastasis prevention.

An Immunomodulator-Boosted Lactococcus Lactis Platform For Enhanced In Situ Tumor Vaccine

In situ vaccination is an attractive type of cancer immunotherapy, and methods of persistently dispersing immune agonists throughout the entire tumor are crucial for maximizing their therapeutic efficacy. Based on the probiotics usually used for dietary supplements, an immunomodulator-boosted Lactococcus lactis (IBL) strategy is developed to enhance the effectiveness of in situ vaccination with the immunomodulators. The intratumoral delivery of OX40 agonist and resiquimod-modified Lactococcus lactis (OR@Lac) facilitates local retention and persistent dispersion of immunomodulators, and dramatically modulates the key components of anti-tumor immune response. This novel vaccine activated dendritic cells and cytotoxic T lymphocytes in the tumor and tumor-draining lymph nodes, and ultimately significantly inhibited tumor growth and prolonged the survival rate of tumor-bearing mice. The combination of OR@Lac and ibrutinib, a myeloid-derived suppressor cell inhibitor, significantly alleviated or even completely inhibited tumor growth in tumor-bearing mice. In conclusion, IBL is a promising in situ tumor vaccine approach for clinical application and provides an inspiration for the delivery of other drugs.

Aptamer-drug conjugates-loaded bacteria for pancreatic cancer synergistic therapy

Pancreatic cancer is one of the most malignant tumors with the highest mortality rates, and it currently lacks effective drugs. Aptamer-drug conjugates (ApDC), as a form of nucleic acid drug, show great potential in cancer therapy. However, the instability of nucleic acid-based drugs in vivo and the avascularity of pancreatic cancer with dense stroma have limited their application. Fortunately, VNP20009, a genetically modified strain of Salmonella typhimurium, which has a preference for anaerobic environments, but is toxic and lacks specificity, can potentially serve as a delivery vehicle for ApDC. Here, we propose a synergistic therapy approach that combines the penetrative capability of bacteria with the targeting and toxic effects of ApDC by conjugating ApDC to VNP20009 through straightforward, one-step click chemistry. With this strategy, bacteria specifically target pancreatic cancer through anaerobic chemotaxis and subsequently adhere to tumor cells driven by the aptamer's specific binding. Results indicate that this method prolongs the serum stability of ApDC up to 48 h and resulted in increased drug concentration at tumor sites compared to the free drugs group. Moreover, the aptamer's targeted binding to cancer cells tripled bacterial colonization at the tumor site, leading to increased death of tumor cells and T cell infiltration. Notably, by integrating chemotherapy and immunotherapy, the effectiveness of the treatment is significantly enhanced, showing consistent results across various animal models. Overall, this strategy takes advantage of bacteria and ApDC and thus presents an effective synergistic strategy for pancreatic cancer treatment.

Nanozymes and their biomolecular conjugates as next-generation antibacterial agents: A comprehensive review

Antimicrobial resistance (AMR), the ability of bacterial species to develop resistance against exposed antibiotics, has gained immense global attention in the past few years. Bacterial infections are serious health concerns affecting millions of people annually worldwide. Therefore, developing novel antibacterial agents that are highly effective and avoid resistance development is imperative. Among various strategies, recent developments in nanozyme technology have shown promising results as antibacterials in several antibiotic-sensitive and resistant bacterial species. Nanozymes offer several advantages over corresponding natural enzymes, such as inexpensive, stable, multifunctional, tunable catalytic properties, etc. Although the use of nanozymes as antibacterial agents has provided promising results, the specific biomolecule-conjugated nanozymes have shown further improvement in catalytic performance and associated antibacterial efficacy. The exclusive design of functional nanozymes with theranostic potential is found to simultaneously inhibit the growth and image of AMR bacterial species. This review comprehensively summarizes the history of nanozymes, their classification, biomolecules conjugated nanozyme, and their mechanism of enzyme-mimetic activity and associated antibacterial activity in antibiotic-sensitive and resistant species. The futureneeds to effectively engineer the existing or new nanozymes to curb AMR have also been discussed.

DNA Molecular Glue Assisted Bacterial Conjugative Transfer

Bacterial conjugation, a commonly used method to horizontally transfer functional genes from donor to recipient strains, plays an important role in the genetic manipulation of bacteria for basic research and industrial production. Successful conjugation depends on the donor-recipient cell recognition and a tight mating junction formation. However, the efficiency of conjugative transfer is usually very low. In this work, we developed a new technique that employed DNA molecule "glue" to increase the match frequency and the interaction stability between the donor and recipient cells. We used two E. coli strains, ETZ and BL21, as a model system, and modified them with the complementary ssDNA oligonucleotides by click chemistry. The conjugation efficiency of the modified bacteria was improved more than 4 times from 10 %-46 %. This technique is simple and generalizable as it only relies on the active amino groups on the bacterial surface. It is expected to have broad applications in constructing engineered bacteria.

Intratumoral Microbiota as a Target for Advanced Cancer Therapeutics

In recent years, advancements in microbial sequencing technology have sparked an increasing interest in the bacteria residing within solid tumors and its distribution and functions in various tumors. Intratumoral bacteria critically modulate tumor oncogenesis and development through DNA damage induction, chronic inflammation, epigenetic alterations, and metabolic and immune regulation, while also influencing cancer treatment efficacy by affecting drug metabolism. In response to these discoveries, a variety of anti-cancer therapies targeting these microorganisms have emerged. These approaches encompass oncolytic therapy utilizing tumor-associated bacteria, the design of biomaterials based on intratumoral bacteria, the use of intratumoral bacterial components for drug delivery systems, and comprehensive strategies aimed at the eradication of tumor-promoting bacteria. Herein, this review article summarizes the distribution patterns of bacteria in different solid tumors, examines their impact on tumors, and evaluates current therapeutic strategies centered on tumor-associated bacteria. Furthermore, the challenges and prospects for developing drugs that target these bacterial communities are also explored, promising new directions for cancer treatment.

Advances in Aptamer-Based Biosensors for the Detection of Foodborne Mycotoxins

Foodborne mycotoxins (FBMTs) are toxins produced by food itself or during processing and transportation that pose an enormous threat to public health security. However, traditional instrumental and chemical methods for detecting toxins have shortcomings, such as high operational difficulty, time consumption, and high cost, that limit their large-scale applications. In recent years, aptamer-based biosensors have become a new tool for food safety risk assessment and monitoring due to their high affinity, good specificity, and fast response. In this review, we focus on the progress of single-mode and dual-mode aptasensors in basic research and device applications over recent years. Furthermore, we also point out some problems in the current detection strategies, with the aim of stimulating future toxin detection systems for a transition toward ease of operation and rapid detection.

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.

Functional modification of gut bacteria for disease diagnosis and treatment

Intestinal bacteria help keep humans healthy by regulating lipid and glucose metabolism as well as the immunological and neurological systems. Oral treatment using intestinal bacteria is limited by the high acidity of stomach fluids and the immune system's attack on foreign bacteria. Scientists have created coatings and workarounds to overcome these limitations and improve bacterial therapy. These preparations have demonstrated promising outcomes, with advances in synthetic biology and optogenetics improving their focused colonization and controlled release. Engineering bacteria preparations have become a revolutionary therapeutic approach that converts intestinal bacteria into cellular factories for medicinal chemical synthesis. The present paper discusses various aspects of engineering bacteria preparations, including wrapping materials, biomedical uses, and future developments.

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.

Intratumoral Microbiome: Foe or Friend in Reshaping the Tumor Microenvironment Landscape?

The role of the microbiome in cancer and its crosstalk with the tumor microenvironment (TME) has been extensively studied and characterized. An emerging field in the cancer microbiome research is the concept of the intratumoral microbiome, which refers to the microbiome residing within the tumor. This microbiome primarily originates from the local microbiome of the tumor-bearing tissue or from translocating microbiome from distant sites, such as the gut. Despite the increasing number of studies on intratumoral microbiome, it remains unclear whether it is a driver or a bystander of oncogenesis and tumor progression. This review aims to elucidate the intricate role of the intratumoral microbiome in tumor development by exploring its effects on reshaping the multileveled ecosystem in which tumors thrive, the TME. To dissect the complexity and the multitude of layers within the TME, we distinguish six specialized tumor microenvironments, namely, the immune, metabolic, hypoxic, acidic, mechanical and innervated microenvironments. Accordingly, we attempt to decipher the effects of the intratumoral microbiome on each specialized microenvironment and ultimately decode its tumor-promoting or tumor-suppressive impact. Additionally, we portray the intratumoral microbiome as an orchestrator in the tumor milieu, fine-tuning the responses in distinct, specialized microenvironments and remodeling the TME in a multileveled and multifaceted manner.

Research progress on the impact of intratumoral microbiota on the immune microenvironment of malignant tumors and its role in immunotherapy

Microbiota has been closely related to human beings, whose role in tumor development has also been widely investigated. However, previous studies have mainly focused on the gut, oral, and/or skin microbiota. In recent years, the study of intratumoral microbiota has become a hot topic in tumor-concerning studies. Intratumoral microbiota plays an important role in the occurrence, development, and response to treatment of malignant tumors. In fact, increasing evidence has suggested that intratumoral microbiota is associated with malignant tumors in various ways, such as promoting the tumor development and affecting the efficacy of chemotherapy and immunotherapy. In this review, the impact of intratumoral microbiota on the immune microenvironment of malignant tumors has been analyzed, as well as its role in tumor immunotherapy, with the hope that it may contribute to the development of diagnostic tools and treatments for related tumors in the future.

Bacteria-based cancer therapy: Looking forward

The field of bacteria-based cancer therapy, which focuses on the key role played by the prevalence of bacteria, specifically in tumors, in controlling potential targets for cancer therapy, has grown enormously over the past few decades. In this review, we discuss, for the first time, the global cancer situation and the timeline for using bacteria in cancer therapy. We also explore how interdisciplinary collaboration has contributed to the evolution of bacteria-based cancer therapies. Additionally, we address the challenges that need to be overcome for bacteria-based cancer therapy to be accepted in clinical trials and the latest advancements in the field. The groundbreaking technologies developed through bacteria-based cancer therapy have opened up new therapeutic strategies for a wide range of therapeutics in cancer.

A next-generation STING agonist MSA-2: From mechanism to application

The stimulator of interferon genes (STING) connects the innate and adaptive immune system and plays a significant role in antitumor immunity. Over the past decades, endogenous and CDN-derived STING agonists have been a hot topic in the research of cancer immunotherapies. However, these STING agonists are either in infancy with limited biological effects or have failed in clinical trials. In 2020, a non-nucleotide STING agonist MSA-2 was identified, which exhibited satisfactory antitumor effects in animal studies and is amenable to oral administration. Due to its distinctive binding mode and enhanced bioavailability, there have been accumulating interests and an array of studies on MSA-2 and its derivatives, spanning its structure-activity relationship, delivery systems, applications in combination therapies, etc. Here, we provide a comprehensive review of MSA-2 and interventional strategies based on this family of STING agonists to help more researchers extend the investigation on MSA-2 in the future.

Lipid-Encapsulated Engineered Bacterial Living Materials Inhibit Cyclooxygenase II to Enhance Doxorubicin Toxicity

Recently, there has been increasing interest in the use of bacteria for cancer therapy due to their ability to selectively target tumor sites and inhibit tumor growth. However, the complexity of the interaction between bacteria and tumor cells evokes unpredictable therapeutic risk, which induces inflammation, stimulates the up-regulation of cyclooxygenase II (COX-2) protein, and stimulates downstream antiapoptotic gene expression in the tumor microenvironment to reduce the antitumor efficacy of chemotherapy and immunotherapy. In this study, we encapsulated celecoxib (CXB), a specific COX-2 inhibitor, in liposomes anchored to the surface of Escherichia coli Nissle 1917 (ECN) through electrostatic absorption (C@ECN) to suppress ECN-induced COX-2 up-regulation and enhance the synergistic antitumor effect of doxorubicin (DOX). C@ECN improved the antitumor effect of DOX by restraining COX-2 expression. In addition, local T lymphocyte infiltration was induced by the ECN to enhance immunotherapy efficacy in the tumor microenvironment. Considering the biosafety of C@ECN, a hypoxia-induced lysis circuit, pGEX-Pvhb-Lysis, was introduced into the ECN to limit the number of ECNs in vivo. Our results indicate that this system has the potential to enhance the synergistic effect of ECN with chemical drugs to inhibit tumor progression in medical oncology.

Near-Infrared-II Nanomaterials for Activatable Photodiagnosis and Phototherapy

Near-Infrared-II (NIR-II) spans wavelengths between 1,000 to 1,700 nanometers, featuring deep tissue penetration and reduced tissue scattering and absorption characteristics, providing robust support for cancer treatment and tumor imaging research. This review explores the utilization of activatable NIR-II photodiagnosis and phototherapy based on tumor microenvironments (e. g., reactive oxygen species, pH, glutathione, hypoxia) and external stimulation (e. g., laser, ultrasound, photothermal) for precise tumor treatment and imaging. Special emphasis is placed on the advancements and advantages of activatable NIR-II nanomedicines in novel therapeutic modalities like photodynamic therapy, photothermal therapy, and photoacoustic imaging. This encompasses achieving deep tumor penetration, real-time monitoring of the treatment process, and obtaining high-resolution, high signal-to-noise ratio images even at low material concentrations. Lastly, from a clinical perspective, the challenges faced by activatable NIR-II phototherapy are discussed, alongside potential strategies to overcome these hurdles.

Bacteria Synergized with PD-1 Blockade Enhance Positive Feedback Loop of Cancer Cells-M1 Macrophages-T Cells in Glioma

Cancer immunotherapy is an attractive strategy because it stimulates immune cells to target malignant cells by regulating the intrinsic activity of the immune system. However, due to lacking many immunologic markers, it remains difficult to treat glioma, a representative "cold" tumor. Herein, to wake the "hot" tumor immunity of glioma, Porphyromonas gingivalis (Pg) is customized with a coating to create an immunogenic tumor microenvironment and further prove the effect in combination with the immune checkpoint agent anti-PD-1, exhibiting elevated therapeutic efficacy. This is accomplished not by enhancing the delivery of PD-1 blockade to enhance the effect of immunotherapy, but by introducing bacterial photothermal therapy to promote greater involvement of M1 cells in the immune response. After reaching glioma, the bacteria further target glioma cells and M2 phenotype macrophages selectively, enabling precise photothermal conversion for lysing tumor cells and M2 phenotype macrophages, which thereby enhances the positive feedback loop of cancer cells-M1 macrophages-T cells. Collectively, the bacteria synergized with PD-1 blockade strategy may be the key to overcoming the immunosuppressive glioma microenvironment and improving the outcome of immunotherapy toward glioma.

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.

Ultra-sensitive and rapid detection of Salmonella enterica and Staphylococcus aureus to single-cell level by aptamer-functionalized carbon nanotube field-effect transistor biosensors

Foodborne diseases caused by Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus) significantly impact public health, underscoring the imperative for highly sensitive, rapid, and accurate detection technologies to ensure food safety and prevent human diseases. Nanomaterials hold great promise in the development of high-sensitivity transistor biosensors. In this work, field-effect transistor (FET) comprising high-purity carbon nanotubes (CNTs) were fabricated and modified with corresponding nucleic acid aptamers for the high-affinity and selective capture of S. enterica and S. aureus. The aptamer-functionalized CNT-FET biosensor demonstrated ultra-sensitive and rapid detection of these foodborne pathogens. Experimental results indicated that the biosensor could detect S. enterica at a limit of detection (LOD) as low as 1 CFU in PBS buffer, and S. aureus at an LOD of 1.2 CFUs, achieving single-cell level detection accuracy with exceptional specificity. The biosensor exhibited a rapid response time, completing single detections within 200 s. Even in the presence of interference from six complex food matrices, the biosensor maintained its ultra-sensitive (3.1 CFUs) and rapid response (within 200 s) characteristics for both pathogens. The developed aptamer-functionalized CNT-FET biosensor demonstrates a capability for low-cost, ultra-sensitive, label-free, and rapid detection of low-abundance S. enterica and S. aureus in both buffer solutions and complex environments. This innovation holds significant potential for applying this detection technology to on-site rapid testing scenarios, offering a promising solution to the pressing need for efficient and reliable pathogen monitoring in various settings.

The emerging tumor microbe microenvironment: From delineation to multidisciplinary approach-based interventions

Intratumoral microbiota has become research hotspots, and emerges as a non-negligent new component of tumor microenvironments (TME), due to its powerful influence on tumor initiation, metastasis, immunosurveillance and prognosis despite in low-biomass. The accumulations of microbes, and their related components and metabolites within tumor tissues, endow TME with additional pluralistic features which are distinct from the conventional one. Therefore, it's definitely necessary to comprehensively delineate the sophisticated landscapes of tumor microbe microenvironment, as well as their functions and related underlying mechanisms. Herein, in this review, we focused on the fields of tumor microbe microenvironment, including the heterogeneity of intratumor microbiota in different types of tumors, the controversial roles of intratumoral microbiota, the basic features of tumor microbe microenvironment (i.e., pathogen-associated molecular patterns (PAMPs), typical microbial metabolites, autophagy, inflammation, multi-faceted immunomodulation and chemoresistance), as well as the multidisciplinary approach-based intervention of tumor microbiome for cancer therapy by applying wild-type or engineered live microbes, microbiota metabolites, antibiotics, synthetic biology and rationally designed biomaterials. We hope our work will provide valuable insight to deeply understand the interplay of cancer-immune-microbial, and facilitate the development of microbes-based tumor-specific treatments.

Micro-to-Nano Oncolytic Microbial System Shifts from Tumor Killing to Tumor Draining Lymph Nodes Remolding for Enhanced Immunotherapy

Because the tumor-draining lymph nodes (TDLNs) microenvironment is commonly immunosuppressive, oncolytic microbe-induced tumor antigens aren't sufficiently cross-primed tumor specific T cells through antigen-presenting cells (e.g., dendritic cells (DCs)) in TDLNs. Herein, this work develops the micro-to-nano oncolytic microbial therapeutics based on pyranose oxidase (P2 O) overexpressed Escherichia coli (EcP) which are simultaneously encapsulated by PEGylated mannose and low-concentrated photosensitizer nanoparticles (NPs). Following administration, P2 O from this system generates toxic hydrogen peroxide for tumor regression and leads to the release of tumor antigens. The "microscale" EcP is triggered, following exposure to the laser irradiation, to secrete the "nanoscale" bacterial outer membrane vesicles (OMVs). The enhanced TDLNs delivery via OMVs significantly regulates the TDLNs immunomicroenvironment, promoting the maturation of DCs to potentiate tumor antigen-specific T cells immune response. The micro-to-nano oncolytic microbe is leveraged to exert tumor killing and remold TDLNs for initiating potent activation of DCs, providing promising strategies to facilitate microbial cancer vaccination.

Bacterial therapies at the interface of synthetic biology and nanomedicine

Bacteria are emerging as living drugs to treat a broad range of disease indications. However, the inherent advantages of these replicating and immunostimulatory therapies also carry the potential for toxicity. Advances in synthetic biology and the integration of nanomedicine can address this challenge through the engineering of controllable systems that regulate spatial and temporal activation for improved safety and efficacy. Here, we review recent progress in nanobiotechnology-driven engineering of bacteria-based therapies, highlighting limitations and opportunities that will facilitate clinical translation.

Bacteria-based drug delivery for treating non-oncological diseases

Bacteria inhabit all over the human body, especially the skin, gastrointestinal tract, respiratory tract, urogenital tract, as well as specific lesion sites, such as wound and tumor. By leveraging their distinctive attributes including rapid proliferation, inherent abilities to colonize various biointerfaces in vivo and produce diverse biomolecules, and the flexibility to be functionalized via genetic engineering or surface modification, bacteria have been widely developed as living therapeutic agents, showing promising potential to make a great impact on the exploration of advanced drug delivery systems. In this review, we present an overview of bacteria-based drug delivery and its applications in treating non-oncological diseases. We systematically summarize the physiological positions where living bacterial therapeutic agents can be delivered to, including the skin, gastrointestinal tract, respiratory tract, and female genital tract. We discuss the success of using bacteria-based drug delivery systems in the treatment of diseases that occur in specific locations, such as skin wound healing/infection, inflammatory bowel disease, respiratory diseases, and vaginitis. We also discuss the advantages as well as the limitations of these living therapeutics and bacteria-based drug delivery, highlighting the key points that need to be considered for further translation. This review article may provide unique insights for designing next-generation bacteria-based therapeutics and developing advanced drug delivery systems.

Bacteria-Based Living Probes: Preparation and the Applications in Bioimaging and Diagnosis

Bacteria can colonize a variety of in vivo biointerfaces, particularly the skin, nasal, and oral mucosa, the gastrointestinal tract, and the reproductive tract, but also target specific lesion sites, such as tumor and wound. By virtue of their prominent characteristics in motility, editability, and targeting ability, bacteria carrying imageable agents are widely developed as living probes for bioimaging and diagnosis of different diseases. This review first introduces the strategies used for preparing bacteria-based living probes, including biological engineering, chemical modification, intracellular loading, and optical manipulation. It then summarizes the recent progress of these living probes for fluorescence imaging, near-infrared imaging, ultrasonic imaging, photoacoustic imaging, magnetic resonance imaging, and positron emission tomography imaging. The biomedical applications of bacteria-based living probes are also reviewed particularly in the bioimaging and diagnosis of bacterial infections, cancers, and intestine-associated diseases. In addition, the advantages and challenges of bacteria-based living probes are discussed and future perspectives are also proposed. This review provides an updated overview of bacteria-based living probes, highlighting their great potential as a unique yet versatile platform for developing next-generation imageable agents for intelligent bioimaging, diagnosis, and even therapy.

Luminescent Gold Nanoparticles with Discrete DNA Valences for Precisely Controlled Transport at the Subcellular Level

Ultrasmall luminescent gold nanoparticles (AuNPs) with excellent capabilities to cross biological barriers offer great promise in designing intelligent model nanomedicines for investigating structure-property relationships at the subcellular level. However, the strict surface controllability of ultrasmall AuNPs is challenging because of their small size. Herein, we report a facile in situ method for precisely controlling DNA aptamer valences on the surface of luminescent AuNPs with emission in the second near-infrared window using a phosphorothioate-modified DNA aptamer, AS1411, as a template. The discrete DNA aptamer number of AS1411-functionalized AuNPs (AS1411-AuNPs, ≈1.8 nm) with emission at 1030 nm was controlled in one aptamer (V1), two aptamers (V2), and four aptamers (V4). It was then discovered that not only the tumor-targeting efficiencies but also the subcellular transport of AS1411-AuNPs were precisely dependent on valences. A slight increase in valence from V1 to V2 increased tumor-targeting efficiencies and resulted in higher nucleus accumulation, whereas a further increase in valence (e.g., V4) significantly increased tumor-targeting efficiencies and led to higher cytomembrane accumulation. These results provide a basis for the strict surface control of nanomedicines in the precise regulation of in vivo transport at the subcellular level and their translation into clinical practice in the future.

Bacteria and Bacterial Components as Natural Bio-Nanocarriers for Drug and Gene Delivery Systems in Cancer Therapy

Bacteria and bacterial components possess multifunctional properties, making them attractive natural bio-nanocarriers for cancer diagnosis and targeted treatment. The inherent tropic and motile nature of bacteria allows them to grow and colonize in hypoxic tumor microenvironments more readily than conventional therapeutic agents and other nanomedicines. However, concerns over biosafety, limited antitumor efficiency, and unclear tumor-targeting mechanisms have restricted the clinical translation and application of natural bio-nanocarriers based on bacteria and bacterial components. Fortunately, bacterial therapies combined with engineering strategies and nanotechnology may be able to reverse a number of challenges for bacterial/bacterial component-based cancer biotherapies. Meanwhile, the combined strategies tend to enhance the versatility of bionanoplasmic nanoplatforms to improve biosafety and inhibit tumorigenesis and metastasis. This review summarizes the advantages and challenges of bacteria and bacterial components in cancer therapy, outlines combinatorial strategies for nanocarriers and bacterial/bacterial components, and discusses their clinical applications.

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.

The role of bacteria and its derived biomaterials in cancer radiotherapy

Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics. It has made significant progress in breaking the limitations of monotherapy and effectively eradicating tumors, especially when combined with traditional therapy, such as radiotherapy. According to their different biological characteristics, bacteria and their derivatives can not only improve the sensitivity of tumor radiotherapy but also protect normal tissues. Moreover, genetically engineered bacteria and bacteria-based biomaterials have further expanded the scope of their applications in radiotherapy. In this review, we have summarized relevant researches on the application of bacteria and its derivatives in radiotherapy in recent years, expounding that the bacteria, bacterial derivatives and bacteria-based biomaterials can not only directly enhance radiotherapy but also improve the anti-tumor effect by improving the tumor microenvironment (TME) and immune effects. Furthermore, some probiotics can also protect normal tissues and organs such as intestines from radiation via anti-inflammatory, anti-oxidation and apoptosis inhibition. In conclusion, the prospect of bacteria in radiotherapy will be very extensive, but its biological safety and mechanism need to be further evaluated and studied.

Self-Assembled Multivalent Aptamer Drug Conjugates: Enhanced Targeting and Cytotoxicity for HER2-Positive Gastric Cancer

Antibody drug conjugates (ADCs) have shown promise to be the mainstream chemotherapeutics for advanced HER2-positive cancers, yet the issues of poor drug delivery efficiency, limited chemotherapeutic effects, severe immune responses, and drug resistance remain to be addressed before the clinical applications of ADCs. The DNA aptamer-guided drug conjugates (ApDCs) are receiving growing attention for specific tumors due to their excellent tumor affinity and low cost. Therefore, developing a multivalent ApDC nanomedicine by combining anti-HER2 aptamer (HApt), tetrahedral framework nucleic acid (tFNA), and deruxtecan (Dxd) together to form HApt-tFNA@Dxd might help to address these concerns. In this study, the HER2-targeted DNA aptamer modified DNA tetrahedron (HApt-tFNA) was employed as a system for drug delivery, and the adoption of tFNA could effectively enlarge the drug-loading rate compared to aptamer-guided ApDCs previously reported. Compared with free Dxd and tFNA@Dxd, HApt-tFNA@Dxd showed better structural stability, excellent targeted cytotoxicity to HER2-positive gastric cancer, and increased tissue aggregation ability in tumors. These features and superiorities make HApt-tFNA@Dxd a promising chemotherapeutic medicine for HER2-positive tumors. Our work developed a new targeting nanomedicine by combining DNA nanomaterials and chemotherapeutic agents, which represents a critical advance toward developing novel DNA-based nanomaterials and promoting their potential applications for HER2-positive cancer therapy.

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.

Cholesterol removal improves performance of a model biomimetic system to co-deliver a photothermal agent and a STING agonist for cancer immunotherapy

Biological membranes often play important functional roles in biomimetic drug delivery systems. We discover that the circulation time and targeting capability of biological membrane coated nanovehicles can be significantly improved by reducing cholesterol level in the coating membrane. A proof-of-concept system using cholesterol-reduced and PD-1-overexpressed T cell membrane to deliver a photothermal agent and a STING agonist is thus fabricated. Comparing with normal membrane, this engineered membrane increases tumor accumulation by ~2-fold. In a melanoma model in male mice, tumors are eliminated with no recurrence in >80% mice after intravenous injection and laser irradiation; while in a colon cancer model in male mice, ~40% mice are cured without laser irradiation. Data suggest that the engineered membranes escape immune surveillance to avoid blood clearance while keeping functional surface molecules exposed. In summary, we develop a simple, effective, safe and widely-applicable biological membrane modification strategy. This "subtractive" strategy displays some advantages and is worth further development.

Bacteria-based immunotherapy for cancer: a systematic review of preclinical studies

Immunotherapy has been emerging as a powerful strategy for cancer management. Recently, accumulating evidence has demonstrated that bacteria-based immunotherapy including naive bacteria, bacterial components, and bacterial derivatives, can modulate immune response via various cellular and molecular pathways. The key mechanisms of bacterial antitumor immunity include inducing immune cells to kill tumor cells directly or reverse the immunosuppressive microenvironment. Currently, bacterial antigens synthesized as vaccine candidates by bioengineering technology are novel antitumor immunotherapy. Especially the combination therapy of bacterial vaccine with conventional therapies may further achieve enhanced therapeutic benefits against cancers. However, the clinical translation of bacteria-based immunotherapy is limited for biosafety concerns and non-uniform production standards. In this review, we aim to summarize immunotherapy strategies based on advanced bacterial therapeutics and discuss their potential for cancer management, we will also propose approaches for optimizing bacteria-based immunotherapy for facilitating clinical translation.

An insight into fluorescence and magnetic resonance bioimaging using a multifunctional polyethyleneimine-passivated gadocarbon dots nanoconstruct assembled with AS1411

A nanoassembly of PEI-passivated Gd@CDs, a type of aptamer, is presented which was designed and characterized in order to target specific cancer cells based on their recognition of the receptor nucleolin (NCL), which is overexpressed on the cell membrane of breast cancer cells for fluorescence and magnetic resonance imaging and treatment. Using hydrothermal methods, Gd-doped nanostructures were synthesized, then modified by a two-step chemical procedure for subsequent applications: the passivating of Gd@CDs with branched polyethyleneimine (PEI) (to form Gd@CDs-PEI1 and Gd@CDs-PEI2), and using AS1411 aptamer (AS) as a DNA-targeted molecule (to generate AS/Gd@CDs-PEI1 and AS/Gd@CDs-PEI2). Consequently, these nanoassemblies were constructed as a result of electrostatic interactions between cationic Gd@CDs-passivated PEI and AS aptamers, offering efficient multimodal targeting nanoassemblies for cancer cell detection. It has been demonstrated through in vitro studies that both types of AS-conjugated nanoassemblies are highly biocompatible, have high cellular uptake efficiency (equivalent concentration of AS: 0.25 μΜ), and enable targeted fluorescence imaging in nucleolin-positive MCF7 and MDA-MB-231 cancer cells compared to MCF10-A normal cells. Importantly, the as-prepared Gd@CDs, Gd@CDs-PEI1, and Gd@CDs-PEI2 exhibit higher longitudinal relaxivity values (r₁) compared with the commercial Gd-DTPA, equal to 5.212, 7.488, and 5.667 mM^-1s^-1, respectively. Accordingly, it is concluded that the prepared nanoassemblies have the potential to become excellent candidates for cancer targeting and fluorescence/MR imaging agents, which can be applied to cancer imaging and personalized nanomedicine.

Nanoscale Organization of TRAIL Trimers using DNA Origami to Promote Clustering of Death Receptor and Cancer Cell Apoptosis

Through inducing death receptor (DR) clustering to activate downstream signaling, tumor necrosis factor related apoptosis inducing ligand (TRAIL) trimers trigger apoptosis of tumor cells. However, the poor agonistic activity of current TRAIL-based therapeutics limits their antitumor efficiency. The nanoscale spatial organization of TRAIL trimers at different interligand distances is still challenging, which is essential for the understanding of interaction pattern between TRAIL and DR. In this study, a flat rectangular DNA origami is employed as display scaffold, and an "engraving-printing" strategy is developed to rapidly decorate three TRAIL monomers onto its surface to form DNA-TRAIL3 trimer (DNA origami with surface decoration of three TRAIL monomers). With the spatial addressability of DNA origami, the interligand distances are precisely controlled from 15 to 60 nm. Through comparing the receptor affinity, agonistic activity and cytotoxicity of these DNA-TRAIL3 trimers, it is found that ≈40 nm is the critical interligand distance of DNA-TRAIL3 trimers to induce death receptor clustering and the resulting apoptosis.Finally, a hypothetical "active unit" model is proposed for the DR5 clustering induced by DNA-TRAIL3 trimers.

Chemically programmable bacterial probes for the recognition of cell surface proteins

Common methods to label cell surface proteins (CSPs) involve the use of fluorescently modified antibodies (Abs) or small-molecule-based ligands. However, optimizing the labeling efficiency of such systems, for example, by modifying them with additional fluorophores or recognition elements, is challenging. Herein we show that effective labeling of CSPs overexpressed in cancer cells and tissues can be obtained with fluorescent probes based on chemically modified bacteria. The bacterial probes (B-probes) are generated by non-covalently linking a bacterial membrane protein to DNA duplexes appended with fluorophores and small-molecule binders of CSPs overexpressed in cancer cells. We show that B-probes are exceptionally simple to prepare and modify because they are generated from self-assembled and easily synthesized components, such as self-replicating bacterial scaffolds and DNA constructs that can be readily appended, at well-defined positions, with various types of dyes and CSP binders. This structural programmability enabled us to create B-probes that can label different types of cancer cells with distinct colors, as well as generate very bright B-probes in which the multiple dyes are spatially separated along the DNA scaffold to avoid self-quenching. This enhancement in the emission signal enabled us to label the cancer cells with greater sensitivity and follow the internalization of the B-probes into these cells. The potential to apply the design principles underlying B-probes in therapy or inhibitor screening is also discussed here.

Coupling Probiotics with 2D CoCuMo-LDH Nanosheets as a Tumor-Microenvironment-Responsive Platform for Precise NIR-II Photodynamic Therapy

Photodynamic therapy (PDT) has become a promising cancer treatment approach with superior advantages. However, it remains a grand challenge to develop tumor microenvironment (TME)-responsive photosensitizers (PSs) for tumor-targeting precise PDT. Herein, the coupling Lactobacillus acidophilus (LA) probiotics with 2D CoCuMo layered-double-hydroxide (LDH) nanosheets (LA&LDH) is reported as a TME-responsive platform for precise NIR-II PDT. The CoCuMo-LDH nanosheets loaded on LA can be transformed from crystalline into amorphous through etching by the LA-metabolite-enabled low pH and overexpressed glutathione. The TME-induced in situ amorphization of CoCuMo-LDH nanosheets can boost its photodynamic activity for singlet oxygen (¹ O₂ ) generation under 1270 nm laser irradiation with relative ¹ O₂ quantum yield of 1.06, which is the highest among previously reported NIR-excited PSs. In vitro and in vivo assays prove that the LA&LDH can effectively achieve complete cell apoptosis and tumor eradication under 1270 nm laser irradiation. This study proves that the probiotics can be used as a tumor-targeting platform for highly efficient precise NIR-II PDT.

The First-in-Human Whole-Body Dynamic Pharmacokinetics Study of Aptamer

Serving as targeting ligands, aptamers have shown promise in precision medicine. However, the lack of knowledge of the biosafety and metabolism patterns in the human body largely impeded aptamers' clinical translation. To bridge this gap, here we report the first-in-human pharmacokinetics study of protein tyrosine kinase 7 targeted SGC8 aptamer via in vivo PET tracking of gallium-68 (⁶⁸Ga) radiolabeled aptamers. The specificity and binding affinity of a radiolabeled aptamer, named ⁶⁸Ga[Ga]-NOTA-SGC8, were maintained as proven in vitro. Further preclinical biosafety and biodistribution evaluation confirmed that aptamers have no biotoxicity, potential mutation risks, or genotoxicity at high dosage (40 mg/kg). Based on this result, a first-in-human clinical trial was approved and carried out to evaluate the circulation and metabolism profiles, as well as biosafety, of the radiolabeled SGC8 aptamer in the human body. Taking advantage of the cutting-edge total-body PET, the aptamers' distribution pattern in the human body was acquired in a dynamic fashion. This study revealed that radiolabeled aptamers are harmless to normal organs and most of them are accumulated in the kidney and cleared from the bladder via urine, which agrees with preclinical studies. Meanwhile, a physiologically based pharmacokinetic model of aptamer was developed, which could potentially predict therapeutic responses and plan personalized treatment strategies. This research studied the biosafety and dynamic pharmacokinetics of aptamers in the human body for the first time, as well as demonstrated the capability of novel molecular imaging fashion in drug development.

A micro-carbon nanotube transistor for ultra-sensitive, label-free, and rapid detection of Staphylococcal enterotoxin C in food

Staphylococcal enterotoxin C (SEC) is an enterotoxin produced by Staphylococcus aureus, which can cause intestinal diseases. Therefore, it is of great significance to develop a sensitive detection method for SEC to ensure food safety and prevent foodborne diseases in humans. A field-effect transistor (FET) based on high-purity carbon nanotubes (CNTs) was used as a transducer, and a nucleic acid aptamer with high affinity was used for recognition to capture the target. The results indicated that the biosensor achieved an ultra-low theoretical detection limit of 1.25 fg/mL in PBS, and its good specificity was verified by detecting target analogs. Three typical food homogenates were used as the solution to be measured to verify that the biosensor had a swift response time (within 5 min after sample addition). An additional study with a more significant basa fish sample response also showed excellent sensitivity (theoretical detection limit of 8.15 fg/mL) and a stable detection ratio. In summary, this CNT-FET biosensor enabled the label-free, ultra-sensitive, and fast detection of SEC in complex samples. The FET biosensors could be further used as a universal biosensor platform for the ultrasensitive detection of multiple biological toxic pollutants, thus considerably stopping the spread of harmful substances.

Inactive Trojan Bacteria as Safe Drug Delivery Vehicles Crossing the Blood-Brain Barrier

Escherichia coli K1 (EC-K1) can bypass the blood-brain barrier (BBB) and cause meningitis. Excitingly, we find the "dead EC-K1" can safely penetrate the BBB because they retain the intact structure and chemotaxis of the live EC-K1, while losing their pathogenicity. Based on this, we develop a safe "dead EC-K1"-based drug delivery system, in which EC-K1 engulf the maltodextrin (MD)-modified therapeutics through the bacteria-specific MD transporter pathway, followed by the inactivation via UV irradiation. We demonstrate that the dead bacteria could carry therapeutics (e.g., indocyanine green (ICG)) and together bypass the BBB after intravenous injection into the mice, delivering ∼3.0-fold higher doses into the brain than free ICG under the same conditions. What is more, all mice remain healthy even after 14 days of intravenous injection of ∼10⁹ CFU of inactive bacteria. As a proof of concept, we demonstrate the developed strategy enables the therapy of bacterial meningitis and glioblastoma in mice.

Bacterial-Mediated Tumor Therapy: Old Treatment in a New Context

Targeted therapy and immunotherapy have brought hopes for precision cancer treatment. However, complex physiological barriers and tumor immunosuppression result in poor efficacy, side effects, and resistance to antitumor therapies. Bacteria-mediated antitumor therapy provides new options to address these challenges. Thanks to their special characteristics, bacteria have excellent ability to destroy tumor cells from the inside and induce innate and adaptive antitumor immune responses. Furthermore, bacterial components, including bacterial vesicles, spores, toxins, metabolites, and other active substances, similarly inherit their unique targeting properties and antitumor capabilities. Bacteria and their accessory products can even be reprogrammed to produce and deliver antitumor agents according to clinical needs. This review first discusses the role of different bacteria in the development of tumorigenesis and the latest advances in bacteria-based delivery platforms and the existing obstacles for application. Moreover, the prospect and challenges of clinical transformation of engineered bacteria are also summarized.

Recent progress of aptamer‒drug conjugates in cancer therapy

Aptamers are single-stranded DNA or RNA sequences that can specifically bind with the target protein or molecule via specific secondary structures. Compared to antibody-drug conjugates (ADC), aptamer‒drug conjugate (ApDC) is also an efficient, targeted drug for cancer therapy with a smaller size, higher chemical stability, lower immunogenicity, faster tissue penetration, and facile engineering. Despite all these advantages, several key factors have delayed the clinical translation of ApDC, such as in vivo off-target effects and potential safety issues. In this review, we highlight the most recent progress in the development of ApDC and discuss solutions to the problems noted above.

Modular-designed engineered bacteria for precision tumor immunotherapy via spatiotemporal manipulation by magnetic field

Micro-nano biorobots based on bacteria have demonstrated great potential for tumor diagnosis and treatment. The bacterial gene expression and drug release should be spatiotemporally controlled to avoid drug release in healthy tissues and undesired toxicity. Herein, we describe an alternating magnetic field-manipulated tumor-homing bacteria developed by genetically modifying engineered Escherichia coli with Fe₃O₄@lipid nanocomposites. After accumulating in orthotopic colon tumors in female mice, the paramagnetic Fe₃O₄ nanoparticles enable the engineered bacteria to receive and convert magnetic signals into heat, thereby initiating expression of lysis proteins under the control of a heat-sensitive promoter. The engineered bacteria then lyse, releasing its anti-CD47 nanobody cargo, that is pre-expressed and within the bacteria. The robust immunogenicity of bacterial lysate cooperates with anti-CD47 nanobody to activate both innate and adaptive immune responses, generating robust antitumor effects against not only orthotopic colon tumors but also distal tumors in female mice. The magnetically engineered bacteria also enable the constant magnetic field-controlled motion for enhanced tumor targeting and increased therapeutic efficacy. Thus, the gene expression and drug release behavior of tumor-homing bacteria can be spatiotemporally manipulated in vivo by a magnetic field, achieving tumor-specific CD47 blockage and precision tumor immunotherapy.

Integrating Bacteria with a Ternary Combination of Photosensitizers for Monochromatic Irradiation-Mediated Photoacoustic Imaging-Guided Synergistic Photothermal Therapy

Photosensitizer-based therapy often suffers from unitary and easily attenuated photosensitive effects, limited tumor penetration and retention, and requirement of multiple irradiation for combination therapy, which largely restrict its application. Here, bacteria are integrated with a monochromatic irradiation-mediated ternary combination of photosensitizers for photoacoustic imaging-guided synergistic photothermal therapy. Bacteria that are bioengineered to express natural melanin are decorated with dual synthetic photosensitizers by nanodeposition with indocyanine green and polydopamine under a cytocompatible condition. The combined photosensitizers, which share an adequate excitation at 808 nm, endow integrated bacteria with a stable triple photoacoustic and photothermal effect under a monochromatic irradiation. Due to their living characteristics, these bacteria preferentially colonize hypoxic tumor tissue with homogeneous distribution and durable retention and generate uniform imaging signals and a sufficient heating of tumor upon laser irradiation. Supported by significantly inhibited tumor growth and extended survival of animals in different tumor-bearing murine models, our work proposes the development of bacteria-based innovative photosensitizers for imaging-guided therapy.