Biomineralization of Bacteria by a Metal-Organic Framework for Therapeutic Delivery

Engineered Microorganisms for Advancing Tumor Therapy

Engineered microorganisms have attracted significant interest as a unique therapeutic platform in tumor treatment. Compared with conventional cancer treatment strategies, engineering microorganism-based systems provide various distinct advantages, such as the intrinsic capability in targeting tumors, their inherent immunogenicity, in situ production of antitumor agents, and multiple synergistic functions to fight against tumors. Herein, the design, preparation, and application of the engineered microorganisms for advanced tumor therapy are thoroughly reviewed. This review presents a comprehensive survey of innovative tumor therapeutic strategies based on a series of representative engineered microorganisms, including bacteria, viruses, microalgae, and fungi. Specifically, it offers extensive analyses of the design principles, engineering strategies, and tumor therapeutic mechanisms, as well as the advantages and limitations of different engineered microorganism-based systems. Finally, the current challenges and future research prospects in this field, which can inspire new ideas for the design of creative tumor therapy paradigms utilizing engineered microorganisms and facilitate their clinical applications, are discussed.

Advances in Nanomaterials for Immunotherapeutic Improvement of Cancer Chemotherapy

Immuno-stimulative effect of chemotherapy (ISECT) is recognized as a potential alternative to conventional immunotherapies, however, the clinical application is constrained by its inefficiency. Metronomic chemotherapy, though designed to overcome these limitations, offers inconsistent results, with effectiveness varying based on cancer types, stages, and patient-specific factors. In parallel, a wealth of preclinical nanomaterials holds considerable promise for ISECT improvement by modulating the cancer-immunity cycle. In the area of biomedical nanomaterials, current literature reviews mainly concentrate on a specific category of nanomaterials and nanotechnological perspectives, while two essential issues are still lacking, i.e., a comprehensive analysis addressing the causes for ISECT inefficiency and a thorough summary elaborating the nanomaterials for ISECT improvement. This review thus aims to fill these gaps and catalyze further development in this field. For the first time, this review comprehensively discusses the causes of ISECT inefficiency. It then meticulously categorizes six types of nanomaterials for improving ISECT. Subsequently, practical strategies are further proposed for addressing inefficient ISECT, along with a detailed discussion on exemplary nanomedicines. Finally, this review provides insights into the challenges and perspectives for improving chemo-immunotherapy by innovations in nanomaterials.

Understanding the bio-crystallization: An insight to therapeutic relevance

In the realm of biomedical engineering and materials science, the synthesis of biomaterials plays a pivotal role in advancing therapeutic strategies for regeneration of tissues. The deliberate control of crystallization processes in biomaterial synthesis has emerged as a key avenue for tailoring the properties of these materials, enabling the design of innovative solutions for a wide array of medical applications. This review delves into the interplay between controlled crystallization and biomaterial synthesis, exploring its multifaceted applications in the therapeutic domains. The investigation encompasses a wide spectrum of matrices, ranging from small molecules to large biomolecules, highlighting their unique contributions in modulating crystallization processes. Furthermore, the review critically assesses the analytical techniques and methodologies employed to probe and characterize the depths of crystallization dynamics. Advanced imaging, spectroscopic, and computational tools are discussed in the context of unraveling the intricate mechanisms governing nucleation and crystallization processes within the organic matrix. Finally we delve in the applications of such advance material in therapeutics of hard and soft tissues.

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.

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.

Engineered Microbial Nanohybrids for Tumor-Mediated NIR II Photothermal Enhanced Ferroptosis/Cuproptosis and Immunotherapy

The colon tumor microenvironment has a high concentration of H2 S and glutathione, which is highly immunosuppressive and adverse to multiple therapeutic methodologies such as ferroptosis. Here, an engineered microbial nanohybrid based on Escherichia coli (E. coli) and Cu2 O nanoparticles to specific colon tumor therapy and immunosuppression reversion is reported. The as-prepared E. coli@Cu2 O hybrid can accumulate in tumor sites upon intravenous injection, and Cu2 O nanoparticles convert to Cux S by consuming the endogenous H2 S, which exhibits strong photothermal conversion at near-infrared II (NIR II) biological window. Furthermore, E. coli@Cu2 O is able to induce cellular ferroptosis and cuproptosis through inactivation of glutathione peroxidase 4 and aggregation of dihydrolipoamide S-acetyltransferase, respectively. Photothermal-enhanced ferroptosis/cuproptosis achieved by E. coli@Cu2 O reverses the immunosuppression of colon tumors by triggering dendritic cell maturation (about 30%) and T cell activation (about 50% CD8+ T cells). Concerted with immune checkpoint blockade, the engineered microbial nanohybrid can inhibit the growth of abscopal tumors upon NIR illumination. Overall, the designed microbial nanohybrid can achieve tumor-specific photothermal-enhanced ferroptosis/cuproptosis and immunosuppression reversion, showing promise in precise tumor therapy in future clinical translation.

Microrod crystals formed via Rhein-mediated mineralization

Herein, a Rhein-mineralized microrod crystal (H-RMM) with an ultra-high drug loading capacity was reported for anti-inflammation. Due to a dense crystal structure, the H-RMM achieved improved biocompatibility and sustained controlled release of Rhein. Also, the Rhein nanofibers released from H-RMM were favorable to be internalized by cells, leading to enhanced anti-inflammation effects.

Cancer phototherapy with nano-bacteria biohybrids

The utilization of light for therapeutic interventions, also known as phototherapy, has been extensively employed in the treatment of a wide range of illnesses, including cancer. Despite the benefits of its non-invasive nature, phototherapy still faces challenges pertaining to the delivery of phototherapeutic agents, phototoxicity, and light delivery. The incorporation of nanomaterials and bacteria in phototherapy has emerged as a promising approach that leverages the unique properties of each component. The resulting nano-bacteria biohybrids exhibit enhanced therapeutic efficacy when compared to either component individually. In this review, we summarize and discuss the various strategies for assembling nano-bacteria biohybrids and their applications in phototherapy. We provide a comprehensive overview of the properties and functionalities of nanomaterials and cells in the biohybrids. Notably, we highlight the roles of bacteria beyond their function as drug vehicles, particularly their capacity to produce bioactive molecules. Despite being in its early stage, the integration of photoelectric nanomaterials and genetically engineered bacteria holds promise as an effective biosystem for antitumor phototherapy. The utilization of nano-bacteria biohybrids in phototherapy is a promising avenue for future investigation, with the potential to enhance treatment outcomes for cancer patients.

Synthetic engineered bacteria for cancer therapy

INTRODUCTION

Cancer mortality worldwide highlights the urgency for advanced therapeutic methods to fill the gaps in conventional cancer therapies. Bacteriotherapy is showing great potential in tumor regression due to the motility and colonization tendencies of bacteria. However, the complicated in vivo environment and tumor pathogenesis hamper the therapeutic outcomes. Synthetic engineering methods endow bacteria with flexible abilities both at the extracellular and intracellular levels to meet treatment requirements. In this review, we introduce synthetic engineering methods for bacterial modifications. We highlight the recent progress in engineered bacteria and explore how these synthetic methods endow bacteria with superior abilities in cancer therapy. The current clinical translations are further discussed. Overall, this review may shed light on the advancement of engineered bacteria for cancer therapy.

AREAS COVERED

Recent progress in synthetic methods for bacterial engineering and specific examples of their applications in cancer therapy are discussed in this review.

EXPERT OPINION

Bacteriotherapy bridges the gaps of conventional cancer therapies through the natural motility and colonization tendency of bacteria, as well as their synthetic engineering. Nevertheless, to fulfill the bacteriotherapy potential and move into clinical trials, more research focusing on its safety concerns should be conducted.

Synergistic glycolysis disturbance for cancer therapy by a MOF-based nanospoiler

Increased glycolysis for promoting adenosine triphosphate (ATP) generation is one of the hallmarks of cancer. Although reducing glucose intake or depriving cellular glucose can delay the growth of tumors to some extent, their therapeutic efficacy is a highly needed improvement for clinical translation. Herein, we found that mannose synergistic with glucose oxidase (GOx) can induce cell death by ATP inhibition, autophagy activation, and apoptosis protein upgradation. By using biodegradable zeolitic imidazolate frameworks (ZIF-8) as a nanocarrier (denoted as ZIF-8/M&G), the mannose and GOx can accumulate at the tumor site while having no obvious long-term toxicity. At the tumor site, GOx inhibits glycolysis by converting glucose and oxygen to H 2O 2 and gluconic acid, realizing oxidation therapy and expediting the degradation of the pH-responsive ZIF-8 nanoparticles, respectively. Simultaneously, mannose disturbs sugar metabolism and reduces oxygen consumption, which in turn promotes the GOx oxidation process. The concerted glycolysis inhibition through interactions between mannose and GOx endows ZIF-8/M&G nanospolier with excellent therapeutic efficacy both in vitro and in vivo. Synergistic glycolysis disturbance by the designed nanospoiler in this work proposes a versatile approach for metabolism disturbance to tumor treatment.

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 advances in MOF-bio-interface: a review

Metal-organic frameworks (MOFs), as a class of promising material with adjustable function and controllable structure, have been widely used in the food industry, chemical industry, biological medicine, and sensors. Biomacromolecules and living systems play a critical role in the world. However, the insufficiency in stability, recyclability, and efficiency, significantly impedes their further utilization in slightly harsh conditions. MOF-bio-interface engineering effectively address the above-mentioned shortages of biomacromolecules and living systems, and thereby attracting considerable attentions. Herein, we systematically review the achievements in the area of MOF-bio-interface. In particular, we summarize the interface between MOFs and proteins (enzymes and non-enzymatic proteins), polysaccharides, DNA, cells, microbes, and viruses. Meanwhile, we discuss the limitations of this approach and propose future research directions. We expect that this review could provide new insights and inspire new research efforts towards life science and material science.

Bacteria-based bioactive materials for cancer imaging and therapy

Owing to the unique biological functions, bacteria as biological materials have been widely used in biomedical field. With advances in biotechnology and nanotechnology, various bacteria-based bioactive materials were developed for cancer imaging and therapy. In this review, different types of bacteria-based bioactive materials and their construction strategies were summarized. The advantages and property-function relationship of bacteria-based bioactive materials were described. Representative researches of bacteria-based bioactive materials in cancer imaging and therapy were illustrated, revealing general ideas for their construction. Also, limitation and challenges of bacteria-based bioactive materials in cancer research were discussed.

Synthesis of Biocompatible Nanoporous ZIF-8-Gum Arabic as a New Carrier for the Targeted Delivery of Curcumin

The synthesis of biocompatible nanoporous zeolitic imidazolate framework-8 (ZIF-8) was performed in the presence of gum arabic (GA), curcumin (CCM), and folic acid (FA) as a template for the biomineralization process, a natural anticancer component, and a targeting agent, respectively. The synthesis of ZIF-8-GA-CCM-FA was completed in a single step at room temperature in aqueous media with a minimum amount of ethanol at a linker/metal molar ratio of 10. FA was dissolved by the alkaline medium produced by a 2-methyl imidazolium (HmIm) linker without using any toxic organic solvent or additional conjugation agents. The FA-modified carrier can target the folate receptors on Hela cells. To the best of our knowledge, this is the first report about the one-pot encapsulation of CCM and FA in a biocompatible ZIF-8-GA framework in a green solvent. This method enables high CCM loading in the ZIF-8-GA framework structure (ca. 90%) at a short time of 15 min. The effect of CCM concentration was investigated on the size, morphology, and crystallinity of the synthesized structures. The products were characterized with field emission scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, X-ray diffraction, Fourier transform infrared, and UV-vis spectroscopy techniques. The release rate of CCM from ZIF-8-GA-CCM-FA was studied at different pH values. In vitro drug release of CCM was higher in the acidic medium (pH 5.5, 6.5) compared to physiological pH (7.4). The cytotoxicity of ZIF-8-GA, ZIF-8-GA-CCM, and ZIF-8-GA-CCM-FA structures was evaluated by the standard 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on the three cell lines (fibroblast (normal cell), Hela (FR-positive), and A549 (FR-negative). These results suggested that the ZIF-8-GA-CCM-FA framework can have a promising effect on the targeted treatment of cancer cells.

Bacteria-mediated cancer therapy: A versatile bio-sapper with translational potential

Bacteria are important symbionts for humans, which sustain substantial influences on our health. Interestingly, some bastrains have been identified to have therapeutic applications, notably for antitumor activity. Thereby, oncologists have developed various therapeutic models and investigated the potential antitumor mechanisms for bacteria-mediated cancer therapy (BCT). Even though BCT has a long history and exhibits remarkable therapeutic efficacy in pre-clinical animal models, its clinical translation still lags and requires further breakthroughs. This review aims to focus on the established strains of therapeutic bacteria and their antitumor mechanisms, including the stimulation of host immune responses, direct cytotoxicity, the interference on cellular signal transduction, extracellular matrix remodeling, neoangiogenesis, and metabolism, as well as vehicles for drug delivery and gene therapy. Moreover, a brief discussion is proposed regarding the important future directions for this fantastic research field of BCT at the end of this review.

Helical micro-swimmer: hierarchical tail design and propulsive motility

Helical micro-swimmers have markedly extended the reach of human beings in numerous fields, ranging from in vitro tasks in lab-on-a-chip to in vivo applications for minimally invasive medicine. The previous studies on the propulsive motility optimization of the micro-swimmers mainly focused on the distinct actuation principles (e.g., chemically powered, magnetic- or ultrasound energy-driven) and paid little attention to the structural design of these swimming machines themselves. The improvements of the structures can assist the externally powered motors in providing propulsion in a tiny scale and satisfy the agile locomotion demands. This paper presents the design, mechanics modeling and available experiments of a novel type of hierarchical helical swimming robot that significantly enhances the motility of the helix-based swimmers. Validated by the resistive force theory, our numerical model can well analyze the mechanical properties with a variety of geometric parameters. The motion performance of the hierarchical and conventional helical structures in low Reynolds regimes is presented, highlighting the advantages of hierarchical swimmers over the existing typical swimmers. In addition, the stability and resilience of the hierarchical swimmers can be maintained at a decent level. Moreover, the variable forward velocity resulting from the combined hierarchical structures is investigated here, which can thereby serve as a reliable design strategy. The proposed hierarchical helical design enables enticing opportunities for various device systems of medical robots and bio-integrated electronics.

Magnetically steerable bacterial microrobots moving in 3D biological matrices for stimuli-responsive cargo delivery

Bacterial biohybrids, composed of self-propelling bacteria carrying micro/nanoscale materials, can deliver their payload to specific regions under magnetic control, enabling additional frontiers in minimally invasive medicine. However, current bacterial biohybrid designs lack high-throughput and facile construction with favorable cargoes, thus underperforming in terms of propulsion, payload efficiency, tissue penetration, and spatiotemporal operation. Here, we report magnetically controlled bacterial biohybrids for targeted localization and multistimuli-responsive drug release in three-dimensional (3D) biological matrices. Magnetic nanoparticles and nanoliposomes loaded with photothermal agents and chemotherapeutic molecules were integrated onto Escherichia coli with ~90% efficiency. Bacterial biohybrids, outperforming previously reported E. coli-based microrobots, retained their original motility and were able to navigate through biological matrices and colonize tumor spheroids under magnetic fields for on-demand release of the drug molecules by near-infrared stimulus. Our work thus provides a multifunctional microrobotic platform for guided locomotion in 3D biological networks and stimuli-responsive delivery of therapeutics for diverse medical applications.

Progress of engineered bacteria for tumor therapy

Recently, with the rapid development of bioengineering technology and nanotechnology, natural bacteria were modified to change their physiological activities and therapeutic functions for improved therapeutic efficiency of diseases. These engineered bacteria were equipped to achieve directed genetic reprogramming, selective functional reorganization and precise spatio-temporal control. In this review, research progress in the basic modification methodologies of engineered bacteria were summarized, and representative researches about their therapeutic performances for tumor treatment were illustrated. Moreover, the strategies for the construction of engineered colonies based on engineering of individual bacteria were summarized, providing innovative ideas for complex functions and efficient anti-tumor treatment. Finally, current limitation and challenges of tumor therapy utilizing engineered bacteria were discussed.

808 nm NIR-triggered Camellia sapogein/curcumin based antibacterial upconversion nanoparticles for synergistic photodynamic-chemical combined therapy

Antibacterial upconversion nanoparticles (UCNP) based photodynamic-chemical combined therapy (UCNP-aPCCT) provides an ideal method to solve the antibiotic-resistant bacteria in deep-tissue infection. Saponin is a kind natural product exhibiting promising antibacterial...

Nanotechnology-Employed Bacteria-Based Delivery Strategy for Enhanced Anticancer Therapy

Bacteria and their derivatives (membrane vesicles, MVs) exhibit great advantages for targeting hypoxic tumor cores, strong penetration ability and activating immune responses, holding great potential as auspicious candidates for therapeutic and drug-delivery applications. However, the safety issues and low therapeutic efficiency by single administration still need to be solved. To further optimize their performance and to utilize their natural abilities, scientists have strived to modify bacteria with new moieties on their surface while preserving their advantages. The aim of this review is to give a comprehensive overview of a non-genetic engineering modification strategy that can be used to optimize the bacteria with nanomaterials and the design strategy that can be used to optimize MVs for better targeted therapy. Here, the advantages and disadvantages of these processes and their applicability for the development of bacteria-related delivery system as antitumor therapeutic agents are discussed. The prospect and the challenges of the above targeted delivery system are also proposed.

Customized materials-assisted microorganisms in tumor therapeutics

Microorganisms have been extensively applied as active biotherapeutic agents or drug delivery vehicles for antitumor treatment because of their unparalleled bio-functionalities. Taking advantage of the living attributes of microorganisms, a new avenue has been opened in anticancer research. The integration of customized functional materials with living microorganisms has demonstrated unprecedented potential in solving existing questions and even conferring microorganisms with updated antitumor abilities and has also provided an innovative train of thought for enhancing the efficacy of microorganism-based tumor therapy. In this review, we have summarized the emerging development of customized materials-assisted microorganisms (MAMO) (including bacteria, viruses, fungi, microalgae, as well as their components) in tumor therapeutics with an emphasis on the rational utilization of chosen microorganisms and tailored materials, the ingenious design of biohybrid systems, and the efficacious antitumor mechanisms. The future perspectives and challenges in this field are also discussed.

Effects of Zeolite as a Drug Delivery System on Cancer Therapy: A Systematic Review

Zeolites and zeolitic imidazolate frameworks (ZIFs) are widely studied as drug carrying nanoplatforms to enhance the specificity and efficacy of traditional anticancer drugs. At present, there is no other systematic review that assesses the potency of zeolites/ZIFs as anticancer drug carriers. Due to the porous nature and inherent pH-sensitive properties of zeolites/ZIFs, the compounds can entrap and selectively release anticancer drugs into the acidic tumor microenvironment. Therefore, it is valuable to provide a comprehensive overview of available evidence on the topic to identify the benefits of the compound as well as potential gaps in knowledge. The purpose of this study was to evaluate the potential therapeutic applications of zeolites/ZIFs as drug delivery systems delivering doxorubicin (DOX), 5-fluorouracil (5-FU), curcumin, cisplatin, and miR-34a. Following PRISMA guidelines, an exhaustive search of PubMed, Scopus, Embase, and Web of Science was conducted. No language or time limitations were used up to 25th August 2021. Only full text articles were selected that pertained to the usage of zeolites/ZIFs in delivering anticancer drugs. Initially, 1279 studies were identified, of which 572 duplicate records were excluded. After screening for the title, abstract, and full texts, 53 articles remained and were included in the qualitative synthesis. An Inter-Rater Reliability (IRR) test, which included a percent user agreement and reliability percent, was conducted for the 53 articles. The included studies suggest that anticancer drug-incorporated zeolites/ZIFs can be used as alternative treatment options to enhance the efficacy of cancer treatment by mitigating the drawbacks of drugs under conventional treatment.

Acridine-Based Covalent Organic Framework Photosensitizer with Broad-Spectrum Light Absorption for Antibacterial Photocatalytic Therapy

Antibiotic resistance is considered as one of the serious public health issues. Antibacterial photocatalytic therapy, a clinically proven antibacterial therapy, is gaining increasing attention in recent years owing to its high efficacy. Here, an acridine-based covalent organic framework (COF) photosensitizer, named TPDA, with multiple active sites is synthesized via Schiff base condensation between 2,4,6-triformylphloroglucinol (TFP) and 3,6-diaminoacridine (DAA). Owing to the increased conjugation effect of the COF skeleton and outstanding light harvesting ability of DAA, TPDA exhibits a narrow optical band gap (1.6 eV), enhancing light energy transformation and conferring a wide optical absorption spectrum (intensity arbitrary unit > 0.8) ranging from the UV to near-infrared region. Moreover, TPDA shows high antibacterial activities against both gram-negative and gram-positive bacteria within a short time (10 min) of light irradiation and is found to efficiently protect fish from skin infections. Molecular dynamics simulation data show that the introduction of DAA and TFP facilitates the interaction between TPDA and bacteria and is conducive to reactive oxygen species migration, which further improves the antimicrobial performance. These findings indicate the potential of TPDA as a novel photosensitive material for photodynamic therapy.

The recent progress on metal-organic frameworks for phototherapy

Some infectious or malignant diseases such as cancers are seriously threatening the health of human beings all over the world. The commonly used antibiotic therapy cannot effectively treat these diseases within a short time, and also bring about adverse effects such as drug resistance and immune system damage during long-term systemic treatment. Phototherapy is an emerging antibiotic-free strategy to treat these diseases. Upon light irradiation, phototherapeutic agents can generate cytotoxic reactive oxygen species (ROS) or induce a temperature increase, which leads to the death of targeted cells. These two kinds of killing strategies are referred to as photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. So far, many photo-responsive agents have been developed. Among them, the metal-organic framework (MOF) is becoming one of the most promising photo-responsive materials because its structure and chemical compositions can be easily modulated to achieve specific functions. MOFs can have intrinsic photodynamic or photothermal ability under the rational design of MOF construction, or serve as the carrier of therapeutic agents, owing to its tunable porosity. MOFs also provide feasibility for various combined therapies and targeting methods, which improves the efficiency of phototherapy. In this review, we firstly investigated the principles of phototherapy, and comprehensively summarized recent advances of MOF in PDT, PTT and synergistic therapy, from construction to modification. We expect that our demonstration will shed light on the future development of this field, and bring it one step closer to clinical trials.

Tumor-targeting inorganic nanomaterials synthesized by living cells

Inorganic nanomaterials (NMs) have shown potential application in tumor-targeting theranostics, owing to their unique physicochemical properties. Some living cells in nature can absorb surrounding ions in the environment and then convert them into nanomaterials after a series of intracellular/extracellular biochemical reactions. Inspired by that, a variety of living cells have been used as biofactories to produce metallic/metallic alloy NMs, metalloid NMs, oxide NMs and chalcogenide NMs, which are usually automatically capped with biomolecules originating from the living cells, benefitting their tumor-targeting applications. In this review, we summarize the biosynthesis of inorganic nanomaterials in different types of living cells including bacteria, fungi, plant cells and animal cells, accompanied by their application in tumor-targeting theranostics. The mechanisms involving inorganic-ion bioreduction and detoxification as well as biomineralization are emphasized. Based on the mechanisms, we describe the size and morphology control of the products via the modulation of precursor ion concentration, pH, temperature, and incubation time, as well as cell metabolism by a genetic engineering strategy. The strengths and weaknesses of these biosynthetic processes are compared in terms of the controllability, scalability and cooperativity during applications. Future research in this area will add to the diversity of available inorganic nanomaterials as well as their quality and biosafety.

Recent Advances in Microswimmers for Biomedical Applications

Microswimmers are a rapidly developing research area attracting enormous attention because of their many potential applications with high societal value. A particularly promising target for cleverly engineered microswimmers is the field of biomedical applications, where many interesting examples have already been reported for e.g., cargo transport and drug delivery, artificial insemination, sensing, indirect manipulation of cells and other microscopic objects, imaging, and microsurgery. Pioneered only two decades ago, research studies on the use of microswimmers in biomedical applications are currently progressing at an incredibly fast pace. Given the recent nature of the research, there are currently no clinically approved microswimmer uses, and it is likely that several years will yet pass before any clinical uses can become a reality. Nevertheless, current research is laying the foundation for clinical translation, as more and more studies explore various strategies for developing biocompatible and biodegradable microswimmers fueled by in vivo-friendly means. The aim of this review is to provide a summary of the reported biomedical applications of microswimmers, with focus on the most recent advances. Finally, the main considerations and challenges for clinical translation and commercialization are discussed.

Biomineralized Biohybrid Algae for Tumor Hypoxia Modulation and Cascade Radio-Photodynamic Therapy

Biomineralization of biomaterials has shown extraordinary potential in cancer treatment, but the exploration of their in vivo applications is still insufficient. Here, we report a biohybrid microalgae system using a biomineralization approach to improve their biocompatibility, while keeping their living activities for radiation and photodynamic synergistic therapy in breast cancer. The biohybrid algae (Algae@SiO₂) synthesized by a one-step biomimetic silicification method could significantly enhance their cytotoxicity and tolerance, improving the living activity in the tumor area. The innate chlorophyll and unique optical property make Algae@SiO₂ possess dual imaging ability, namely, photoacoustic imaging and fluorescence imaging. Algae@SiO₂ accumulated in tumor sites could generate oxygen in situ by external light-mediated photosynthesis, relieve tumor hypoxia, and then enhance the efficiency of radiation therapy. As a natural photosensitizer, the released chlorophyll from Algae@SiO₂ could provide reactive oxygen species to kill the cancer cells for the cascaded photodynamic therapy. The significant suppression of tumor growth in the mice bearing 4T1 tumor successfully demonstrates the promising anti-tumor effect of the Algae@SiO₂-mediated synergistic therapy. Our results show that biohybrid algae, integrated with PAI/FI dual imaging, radiosensitization, and cascaded photothermal therapy, is a promising multifunctional efficient biosystem for cancer treatment.