Persistent luminescence phosphor as in-vivo light source for tumoral cyanobacterial photosynthetic oxygenation and photodynamic therapy

Innovative Applications of Bacteria and Their Derivatives in Targeted Tumor Therapy

Despite significant progress in cancer treatment, traditional therapies still face considerable challenges, including poor targeting, severe toxic side effects, and the development of resistance. Recent advances in biotechnology have revealed the potential of bacteria and their derivatives as drug delivery systems for tumor therapy by leveraging their biological properties. Engineered bacteria, including Escherichia coli, Salmonella, and Listeria monocytogenes, along with their derivatives─outer membrane vesicles (OMVs), bacterial ghosts (BGs), and bacterial spores (BSPs)─can be loaded with a variety of antitumor agents, enabling precise targeting and sustained drug release within the tumor microenvironment (TME). These bacteria and their derivatives possess intrinsic properties that stimulate the immune system, enhancing both innate and adaptive immune responses to further amplify therapeutic effects. The ability of bacteria to naturally accumulate in hypoxic tumor regions and their versatility in genetic modifications allow for tailored drug delivery strategies that synergistically enhance the effectiveness of chemotherapy, immunotherapy, and targeted therapies. This review comprehensively examines the fundamental principles of bacterial therapy, focusing on the strategies employed for bacterial engineering, drug loading, and the use of bacteria and their derivatives in targeted tumor therapy. It also discusses the challenges faced in optimizing bacterial delivery systems, such as safety concerns, unintended immune responses, and scalability for clinical applications. By exploring these aspects, this review provides a theoretical framework for improving bacterial-based drug delivery systems, contributing to the development of more effective and personalized cancer treatments.

Photosynthetic Bacteria: Light-Responsive Biomaterials for Anti-Tumor Photodynamic Therapy

Photodynamic therapy (PDT) is a promising noninvasive tumor treatment modality that relies on generating reactive oxygen species (ROS) and requires an adequate oxygen supply to the target tissue. However, hypoxia is a common feature of solid tumors and profoundly restricts the anti-tumor efficacy of PDT. In recent years, scholars have focused on exploring nanomaterial-based strategies for oxygen supplementation and integrating non-oxygen-consuming treatment approaches to overcome the hypoxic limitations of PDT. Some scholars have harnessed the photosynthetic oxygen production of cyanobacteria under light irradiation to overcome tumor hypoxia and engineered them as carriers of photosensitizers instead of inorganic nanomaterials, resulting in photosynthetic bacteria (PSB) attracting significant attention. Recent studies have shown that light-triggered PSB can exhibit additional properties, such as photosynthetic hydrogen production, ROS generation, and photothermal conversion, facilitating their use as promising light-responsive biomaterials for enhancing the anti-tumor efficacy of PDT. Therefore, understanding PSB can provide new insights and ideas for future research. This review mainly introduces the characteristics of PSB and recent research on light-triggered PSB in anti-tumor PDT to enrich our knowledge in this area. Finally, the challenges and prospects of using PSB to enhance the anti-tumor efficacy of PDT were also discussed.

Oxygenation by Intravascular Photosynthesis Reduces Kidney Damage During ex Vivo Preservation

Several clinical issues are associated with reduced oxygen delivery to tissues due to impaired vascular perfusion; moreover, organs procured for transplantation are subjected to severe hypoxia during preservation. Consequently, alternative tissue oxygenation is an active field in biomedical research where several innovative approaches have been recently proposed. Among these, intravascular photosynthesis represents a promising approach as it relies on the intrinsic capacity of certain microorganisms to produce oxygen upon illumination. In this context, this work aims at the development of photosynthetic perfusable solutions that could be applied to preserve organs for transplantation purposes. Our findings demonstrate that a biocompatible physiological solution containing the photosynthetic microalgae Chlamydomonas reinhardtii can fulfill the metabolic oxygen demand of rat kidney slices in vitro. Furthermore, intravascular administration of this solution does not induce tissue damage in the rat kidneys. Moreover, kidney slices obtained from these algae-perfused organs exhibited significantly improved preservation after 24 h of incubation in hypoxia while exposed to light, resulting in reduced tissue damage and enhanced metabolic status. Overall, the results presented here contribute to the development of alternative strategies for tissue oxygenation, supporting the use of perfusable photosynthetic solutions for organ preservation in transplantation.

The Rational Engineered Bacteria Based Biohybrid Living System for Tumor Therapy

Living therapy based on bacterial cells has gained increasing attention for their applications in tumor treatments. Bacterial cells can naturally target to tumor sites and active the innate immunological responses. The intrinsic advantages of bacteria attribute to the development of biohybrid living carriers for targeting delivery toward hypoxic environments. The rationally engineered bacterial cells integrate various functions to enhance the tumor therapy and reduce toxic side effects. In this review, the antitumor effects of bacteria and their application are discussed as living therapeutic agents across multiple antitumor platforms. The various kinds of bacteria used for cancer therapy are first introduced and demonstrated the mechanism of antitumor effects as well as the immunological effects. Additionally, this study focused on the genetically modified bacteria for the production of antitumor agents as living delivery system to treat cancer. The combination of living bacterial cells with functional nanomaterials is then discussed in the cancer treatments. In brief, the rational design of living therapy based on bacterial cells highlighted a rapid development in tumor therapy and pointed out the potentials in clinical applications.

Towards chlorocytes for therapeutic intravascular photosynthesis

Aerobic metabolism relies on external oxygen production through photosynthesis and its subsequent transport into each cell of the body via the cardiorespiratory system. This mechanism has successfully evolved over millions of years, enabling animals to inhabit most environments on Earth. However, the insufficient oxygen supply leads to several clinical problems, ranging from non-healing wounds to tumor resistance to therapy. Given that photosynthetic microorganisms are capable of producing oxygen and removing carbon dioxide from the environment, over the last decade, several groups worldwide have proposed their potential use as an alternative tissue oxygenation approach. While most studies have demonstrated safety and efficacy after local tissue administration, recent studies have also suggested that systemic administration could trigger intravascular photosynthesis. If successful, the development of a new generation of circulating cells, known as chlorocytes, may partially replace the role of erythrocytes in gas exchange within the body, without relying on external supply and vascular flow. This work reviews the existing literature on local and systemic administration of photosynthetic microorganisms, highlighting the main challenges in the field and potential solutions to unleash the enormous potential clinical impact of chlorocytes and intravascular photosynthesis. KEY POINTS: • Circulating photosynthetic microorganisms could deliver oxygen to tissues • Microalgae and cyanobacteria have shown safety and efficacy for oxygen delivery • Several key challenges need to be addressed for the clinical success of chlorocytes.

Biomedical application of microalgal-biomaterials hybrid system

Microalgae are a group of microorganisms containing chlorophyll A, which are highly photosynthetic and rich in nutrients. And they can produce multiple bioactive substances (peptides, proteins, polysaccharides, and fatty acids) for biomedical applications. Despite the unique advantages of microalgae-based biotherapy, the insufficient treatment efficiency limits its further application. With the development of nanotechnology, the combination of microalgae and biomaterials can improve therapeutic efficacies, which has attracted increasing attention. In this microalgal-biomaterials hybrid system, biomaterials with excellent optical and magnetic properties play an important role in biological therapy. Microalgae, as a natural vehicle, can increase oxygen content and alleviate hypoxia in diseased areas, further enhancing therapeutic effects. In this review, the synergistic therapeutic effects of microalgal-biomaterials hybrid system in different diseases (cancer, myocardial infarction, ischemia stroke, chronic infection, and intestinal diseases) are comprehensively summarized.

Bioimaging and prospects of night pearls-based persistence phosphors in cancer diagnostics

Inorganic persistent phosphors feature great potential for cancer diagnosis due to the long luminescence lifetime, low background scattering, and minimal autofluorescence. With the prominent advantages of near-infrared light, such as deep penetration, high resolution, low autofluorescence, and tissue absorption, persistent phosphors can be used for deep bioimaging. We focus on highlighting inorganic persistent phosphors, emphasizing the synthesis methods and applications in cancer diagnostics. Typical synthetic methods such as the high-temperature solid state, thermal decomposition, hydrothermal/solvothermal, and template methods are proposed to obtain small-size phosphors for biological organisms. The luminescence mechanisms of inorganic persistent phosphors with different excitation are discussed and effective matrixes including galliumate, germanium, aluminate, and fluoride are explored. Finally, the current directions where inorganic persistent phosphors can continue to be optimized and how to further overcome the challenges in cancer diagnosis are summarized.

Nanomaterial-assisted oncolytic bacteria in solid tumor diagnosis and therapeutics

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

Persistent luminescent nanophosphors for applications in cancer theranostics, biomedical, imaging and security

The extraordinary and unique properties of persistent luminescent (PerLum) nanostructures like storage of charge carriers, extended afterglow, and some other fascinating characteristics like no need for in-situ excitation, and rechargeable luminescence make such materials a primary candidate in the fields of bio-imaging and therapeutics. Apart from this, due to their extraordinary properties they have also found their place in the fields of anti-counterfeiting, latent fingerprinting (LPF), luminescent markings, photocatalysis, solid-state lighting devices, glow-in-dark toys, etc. Over the past few years, persistent luminescent nanoparticles (PLNPs) have been extensively used for targeted drug delivery, bio-imaging guided photodynamic and photo-thermal therapy, biosensing for cancer detection and subsequent treatment, latent fingerprinting, and anti-counterfeiting owing to their enhanced charge storage ability, in-vitro excitation, increased duration of time between excitation and emission, low tissue absorption, high signal-to-noise ratio, etc. In this review, we have focused on most of the key aspects related to PLNPs, including the different mechanisms leading to such phenomena, key fabrication techniques, properties of hosts and different activators, emission, and excitation characteristics, and important properties of trap states. This review article focuses on recent advances in cancer theranostics with the help of PLNPs. Recent advances in using PLNPs for anti-counterfeiting and latent fingerprinting are also discussed in this review.

Dual-driven nanomotors enable tumor penetration and hypoxia alleviation for calcium overload-photo-immunotherapy against colorectal cancer

The treatment efficacies of conventional medications against colorectal cancer (CRC) are restricted by a low penetrative, hypoxic, and immunosuppressive tumor microenvironment. To address these restrictions, we developed an innovative antitumor platform that employs calcium overload-phototherapy using mitochondrial N770-conjugated mesoporous silica nanoparticles loaded with CaO2 (CaO2-N770@MSNs). A loading level of 14.0 wt% for CaO2-N770@MSNs was measured, constituting an adequate therapeutic dosage. With the combination of oxygen generated from CaO2 and hyperthermia under near-infrared irradiation, CaO2-N770@MSNs penetrated through the dense mucus, accumulated in the colorectal tumor tissues, and inhibited tumor cell growth through endoplasmic reticulum stress and mitochondrial damage. The combination of calcium overload and phototherapy revealed high therapeutic efficacy against orthotopic colorectal tumors, alleviated the immunosuppressive microenvironment, elevated the abundance of beneficial microorganisms (e.g., Lactobacillaceae and Lachnospiraceae), and decreased harmful microorganisms (e.g., Bacteroidaceae and Muribaculaceae). Moreover, together with immune checkpoint blocker (αPD-L1), these nanoparticles showed an ability to eradicate both orthotopic and distant tumors, while potentiating systemic antitumor immunity. This treatment platform (CaO2-N770@MSNs plus αPD-L1) open a new horizon of synergistic treatment against hypoxic CRC with high killing power and safety.

Recent Advances in Nanoplatform Construction Strategy for Alleviating Tumor Hypoxia

Hypoxia is a typical feature of most solid tumors and has important effects on tumor cells' proliferation, invasion, and metastasis. This is the key factor that leads to poor efficacy of different kinds of therapy including chemotherapy, radiotherapy, photodynamic therapy, etc. In recent years, the construction of hypoxia-relieving functional nanoplatforms through nanotechnology has become a new strategy to reverse the current situation of tumor microenvironment hypoxia and improve the effectiveness of tumor treatment. Here, the main strategies and recent progress in constructing nanoplatforms are focused on to directly carry oxygen, generate oxygen in situ, inhibit mitochondrial respiration, and enhance blood perfusion to alleviate tumor hypoxia. The advantages and disadvantages of these nanoplatforms are compared. Meanwhile, nanoplatforms based on organic and inorganic substances are also summarized and classified. Through the comprehensive overview, it is hoped that the summary of these nanoplatforms for alleviating hypoxia could provide new enlightenment and prospects for the construction of nanomaterials in this field.

Engineered photoresponsive biohybrids for tumor therapy

Engineered biohybrids have recently emerged as innovative biomimetic platforms for cancer therapeutic applications. Particularly, engineered photoresponsive biohybrids hold tremendous potential against tumors due to their intriguing biomimetic properties, photoresponsive ability, and enhanced biotherapeutic functions. In this review, the design principles of engineered photoresponsive biohybrids and their latest progresses for tumor therapy are summarized. Representative engineered photoresponsive biohybrids are highlighted including biomolecules-associated, cell membrane-based, eukaryotic cell-based, bacteria-based, and algae-based photoresponsive biohybrids. Representative tumor therapeutic modalities of the engineered photoresponsive biohybrids are presented, including photothermal therapy, photodynamic therapy, synergistic therapy, and tumor therapy combined with tissue regeneration. Moreover, the challenges and future perspectives of these photoresponsive biohybrids for clinical practice are discussed.

Nanoparticles-based phototherapy systems for cancer treatment: Current status and clinical potential

Remarkable progress in phototherapy has been made in recent decades, due to its non-invasiveness and instant therapeutic efficacy. In addition, with the rapid development of nanoscience and nanotechnology, phototherapy systems based on nanoparticles or nanocomposites also evolved as an emerging hotspot in nanomedicine research, especially in cancer. In this review, first we briefly introduce the history of phototherapy, and the mechanisms of phototherapy in cancer treatment. Then, we summarize the representative development over the past three to five years in nanoparticle-based phototherapy and highlight the design of the innovative nanoparticles thereof. Finally, we discuss the feasibility and the potential of the nanoparticle-based phototherapy systems in clinical anticancer therapeutic applications, aiming to predict future research directions in this field. Our review is a tutorial work, aiming at providing useful insights to researchers in the field of nanotechnology, nanoscience and cancer.

Recent Advances in Hydrogel-Based Phototherapy for Tumor Treatment

Phototherapeutic agent-based phototherapies activated by light have proven to be safe modalities for the treatment of various malignant tumor indications. The two main modalities of phototherapies include photothermal therapy, which causes localized thermal damage to target lesions, and photodynamic therapy, which causes localized chemical damage by generated reactive oxygen species (ROS). Conventional phototherapies suffer a major shortcoming in their clinical application due to their phototoxicity, which primarily arises from the uncontrolled distribution of phototherapeutic agents in vivo. For successful antitumor phototherapy, it is essential to ensure the generation of heat or ROS specifically occurs at the tumor site. To minimize the reverse side effects of phototherapy while improving its therapeutic performance, extensive research has focused on developing hydrogel-based phototherapy for tumor treatment. The utilization of hydrogels as drug carriers allows for the sustained delivery of phototherapeutic agents to tumor sites, thereby limiting their adverse effects. Herein, we summarize the recent advancements in the design of hydrogels for antitumor phototherapy, offer a comprehensive overview of the latest advances in hydrogel-based phototherapy and its combination with other therapeutic modalities for tumor treatment, and discuss the current clinical status of hydrogel-based antitumor phototherapy.

Redox-responsive degradable microgel modified with superparamagnetic nanoparticles exhibiting controlled, hyperthermia-enhanced drug release

A novel degradable microgel based on poly(N-isopropylacrylamide) (pNIPA) cross-linked with N,N’-bisacryloylcystine (BISS) and containing superparamagnetic iron oxide nanoparticles (SPION@CA) was synthesized by semi-batch precipitation polymerization and examined as a potential hyperthermia-enhanced drug carrier. The pNIPA provided the microgel with temperature sensitivity, the BISS was responsible for degradation in the presence of glutathione (GSH) (an –S–S–bond reductor naturally present in cells), while the SPION@CA permitted remote control of temperature to improve drug release. The microgels exhibited volume phase transition temperature at ca. 34 °C, which is near the human body temperature, and were stable across a wide range of temperatures and ionic strengths, as well as in the blood plasma at 37 °C. It was found that the presence of SPION@CA in the polymer network of the microgels enabled the temperature to be increased up to 42 °C by an alternating magnetic field, and that increasing the temperature from 37 to 42 °C significantly enhanced the releasing of the anticancer drug doxorubicin (DOX). The highest DOX release (82%) was observed at pH 5, 42 °C, and in the presence of GSH, and the lowest (20%) at pH 7.4, 37 °C, and in the absence of GSH. MTT assay indicated that compared to free doxorubicin, the microgel particles loaded with doxorubicin have comparable cytotoxicity against MCF-7 cancer cells while being significantly less toxic to MCF-10A healthy cells.

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Development of a photosynthetic hydrogel as potential wound dressing for the local delivery of oxygen and bioactive molecules

The development of biomaterials to improve wound healing is a critical clinical challenge and an active field of research. As it is well described that oxygen plays a critical role in almost each step of the wound healing process, in this work, an oxygen producing photosynthetic biomaterial was generated, characterized, and further modified to additionally release other bioactive molecules. Here, alginate hydrogels were loaded with the photosynthetic microalgae Chlamydomonas reinhardtii, showing high integration as well as immediate oxygen release upon illumination. Moreover, the photosynthetic hydrogel showed high biocompatibility in vitro and in vivo, and the capacity to sustain the metabolic oxygen requirements of zebrafish larvae and skin explants. In addition, the photosynthetic dressings were evaluated in 20 healthy human volunteers following the ISO-10993-10-2010 showing no skin irritation, mechanical stability of the dressings, and survival of the photosynthetic microalgae. Finally, hydrogels were also loaded with genetically engineered microalgae to release human VEGF, or pre-loaded with antibiotics, showing sustained release of both bioactive molecules. Overall, this work shows that photosynthetic hydrogels represent a feasible approach for the local delivery of oxygen and other bioactive molecules to promote wound healing. STATEMENT OF SIGNIFICANCE: As oxygen plays a key role in almost every step of the tissue regeneration process, the development of oxygen delivering therapies represents an active field of research, where photosynthetic biomaterials have risen as a promising approach for wound healing. Therefore, in this work a photosynthetic alginate hydrogel-based wound dressing containing C. reinhardtii microalgae was developed and validated in healthy skin of human volunteers. Moreover, hydrogels were modified to additionally release other bioactive molecules such as recombinant VEGF or antibiotics. The present study provides key scientific data to support the use of photosynthetic hydrogels as customizable dressings to promote wound healing.

Innovative strategies for photodynamic therapy against hypoxic tumor

Photodynamic therapy (PDT) is applied as a robust therapeutic option for tumor, which exhibits some advantages of unique selectivity and irreversible damage to tumor cells. Among which, photosensitizer (PS), appropriate laser irradiation and oxygen (O₂) are three essential components for PDT, but the hypoxic tumor microenvironment (TME) restricts the O₂ supply in tumor tissues. Even worse, tumor metastasis and drug resistance frequently happen under hypoxic condition, which further deteriorate the antitumor effect of PDT. To enhance the PDT efficiency, critical attention has been received by relieving tumor hypoxia, and innovative strategies on this topic continue to emerge. Traditionally, the O₂ supplement strategy is considered as a direct and effective strategy to relieve TME, whereas it is confronted with great challenges for continuous O₂ supply. Recently, O₂-independent PDT provides a brand new strategy to enhance the antitumor efficiency, which can avoid the influence of TME. In addition, PDT can synergize with other antitumor strategies, such as chemotherapy, immunotherapy, photothermal therapy (PTT) and starvation therapy, to remedy the inadequate PDT effect under hypoxia conditions. In this paper, we summarized the latest progresses in the development of innovative strategies to improve PDT efficacy against hypoxic tumor, which were classified into O₂-dependent PDT, O₂-independent PDT and synergistic therapy. Furthermore, the advantages and deficiencies of various strategies were also discussed to envisage the prospects and challenges in future study.

The development of live microorganism-based oxygen shuttles for enhanced hypoxic tumor therapy

Hypoxia is a prominent feature of malignant tumors and contributes to tumor proliferation, metastasis, and drug resistance in various solid tumors. Therefore, improving tumor oxygenation is crucial for curing tumors. To date, multiple strategies, including oxygen delivering and producing materials, have been designed to increase the oxygen concentration in hypoxic tumors. However, the unsustainable supply of oxygen is still the main obstacle, resulting in a suboptimal outcome in treating oxygen-deprived tumors. Thus, a sufficient oxygen supply is highly desirable in the treatment of hypoxic tumors. Photosynthesis, as the main source of oxygen in nature through the conversion of light energy into chemical energy and oxygen, has been widely studied in scientific research. Moreover, photosynthetic microorganisms have been increasingly applied in cancer therapy by increasing oxygenation, which improves the therapeutic effect of oxygen-consuming tumor therapeutic tools such as radiotherapy and photodynamic therapy. In this review, we summarize recent advances in the design and manufacture of live bacteria as oxygen shuttles for a new generation of hypoxic tumor treatment strategies. Finally, current challenges and future directions are also discussed for successfully addressing hypoxic tumor issues.

A tumor pH-responsive autocatalytic nanoreactor as a H2O2 and O2 self-supplying depot for enhanced ROS-based chemo/photodynamic therapy

Combining the internal force-driven chemodynamic therapy (CDT) and the external energy-triggered photodynamic therapy (PDT) holds great promise to achieve an advanced anticancer effect based on reactive oxygen species (ROS). However, the insufficient oxy-substrates supply in tumor microenvironment, like hydrogen peroxide (H₂O₂) and oxygen (O₂), is the Achilles heel that greatly restricts the efficacy of this ROS-based treatment. Herein, the construction of a copper peroxide-based tumor pH-responsive autocatalytic nanoreactor (CESAR), via an albumin-mediated biomimetic mineralization strategy is described. The decoration of human serum albumin endows the nanoreactor good hydrophilicity and biocompatibility, which is highly desired for the metal-based materials. Upon exposure to acidic tumor microenvironment, CESAR presents a pH-triggered disintegration with Cu²⁺, H₂O₂ and O₂ generated instantly. The generated H₂O₂ complements the hyperoxide deficiency and initiates a localized Fenton-like reaction with the assistance of Cu²⁺ for highly toxic hydroxyl radicals (•OH) production for improving CDT. The evolved O₂ gas enables hypoxia relief for enhanced Ce6-mediated PDT. This H₂O₂/O₂ self-supplying strategy significantly amplifies the tumor oxidative damage and gains an optimal treatment outcome, which offers a new paradigm for optimizing the tumor therapeutic options limited by oxide or hyperoxide deficiency, not only for CDT/PDT, but also other oxy-substrates involved strategies. STATEMENT OF SIGNIFICANCE: The shortage of oxy-substrates in the tumor microenvironment remains a great challenge for ROS-based cancer therapy. Herein, we introduce human serum albumin as a scaffold to stabilize copper peroxide nanomaterials for constant production of H₂O₂ and O₂ to enhance chemodynamic/photodynamic therapy. The tumor pH-triggered H₂O₂/O₂ production and Cu²⁺ release are confirmed, assuring the strategy of a highly precise, effective way to destroy tumor without any side effects. This work lends new and exciting insights into the engineering design of autocatalytic oxy-substrates self-supply nanoreactor for overcoming the bottlenecks, like the oxy-substrates deficiency of CDT/PDT and the poor stability of metal peroxides, to achieve highly effective chemodynamic/photodynamic therapy.

Recent advances in bacteria-mediated cancer therapy

Cancer is among the leading cause of deaths worldwide. Although conventional therapies have been applied in the fight against the cancer, the poor oxygen, low extracellular pH, and high interstitial fluid pressure of the tumor microenvironment mean that these treatments fail to completely eradicate cancer cells. Recently, bacteria have increasingly been considered to be a promising platform for cancer therapy thanks to their many unique properties, such as specific tumor-targeting ability, high motility, immunogenicity, and their use as gene or drug carriers. Several types of bacteria have already been used for solid and metastatic tumor therapies, with promising results. With the development of synthetic biology, engineered bacteria have been endowed with the controllable expression of therapeutic proteins. Meanwhile, nanomaterials have been widely used to modify bacteria for targeted drug delivery, photothermal therapy, magnetothermal therapy, and photodynamic therapy, while promoting the antitumor efficiency of synergistic cancer therapies. This review will provide a brief introduction to the foundation of bacterial biotherapy. We begin by summarizing the recent advances in the use of many different types of bacteria in multiple targeted tumor therapies. We will then discuss the future prospects of bacteria-mediated cancer therapies.

Engineered Red Blood Cell Membrane-Coating Salidroside/Indocyanine Green Nanovesicles for High-Efficiency Hypoxic Targeting Phototherapy of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) presents special biological behavior and clinicopathological characteristics and leads to a worse prognosis than other types of breast cancer. The development of an effective therapeutic method is significant to improve the survival rate of TNBC cancer patients. In this work, an engineered red blood cell membrane (RBCm)-coating salidroside/indocyanine green nanovesicle (ARISP) is successfully prepared for hypoxic targeting phototherapy of TNBC. Salidroside in ARISP effectively ameliorates hypoxia-induced tumorigenesis by downregulating the expression of hypoxia-inducible factor 1α (HIF-1α), which increases the killing effect of reactive oxygen species on tumor cells during photodynamic therapy (PDT) using the photosensitizer indocyanine green. Besides, ARISP has an anti-LDLR modified RBCm-coating that extends its circulation time in the blood and escapes from immune surveillance and enhances hypoxia-targeted cellular uptake via the overexpressed LDLR receptor in hypoxic tumor sites. Moreover, guided by near-infrared fluorescence imaging and photoacoustic imaging, ARISP can eliminate tumors via high-efficiency phototherapy and inhibit lung and liver metastasis in TNBC models. Cytotoxicity assay of ARISP indicates the excellent biocompatibility with normal cells and tissues. This study provides fulfilling insights into the anticancer mechanism of reducing HIF-1α for enhanced PDT and has a promising therapeutic potential for TNBC treatment.

Scalable Manufacture of Curcumin-Loaded Chitosan Nanocomplex for pH-Responsive Delivery by Coordination-Driven Flash Nanocomplexation

Metal coordination-driven nanocomplexes are known to be responsive to physiologically relevant stimuli such as pH, redox, temperature or light, making them well-suited for antitumor drug delivery. The ever-growing demand for such nanocomplexes necessitates the design of a scalable approach for their production. In this study, we demonstrate a novel coordination self-assembly strategy, termed flash nanocomplexation (FNC), which is rapid and efficient for the fabrication of drug-loaded nanoparticles (NPs) in a continuous manner. Based on this strategy, biocompatible chitosan (CS) and Cu2+ can be regarded anchors to moor the antitumor drug (curcumin, Cur) through coordination, resulting in curcumin-loaded chitosan nanocomplex (Cur-loaded CS nanocomplex) with a narrow size distribution (PDI < 0.124) and high drug loading (up to 41.75%). Owing to the excellent stability of Cur-loaded CS nanocomplex at neutral conditions (>50 days), premature Cur leakage was limited to lower than 1.5%, and pH-responsive drug release behavior was realized in acidic tumor microenvironments. An upscaled manufacture of Cur-loaded CS nanocomplex is demonstrated with continuous FNC, which shows an unprecedented method toward practical applications of nanomedicine for tumor therapy. Furthermore, intracellular uptake study and cytotoxicity experiments toward H1299 cells demonstrates the satisfied anticancer efficacy of the Cur-loaded CS nanocomplex. These results confirm that coordination-driven FNC is an effective method that enables the rapid and scalable fabrication of antitumor drugs.