Oxygen-producing catalase-based prodrug nanoparticles overcoming resistance in hypoxia-mediated chemo-photodynamic therapy

Enzymes in Addressing Hypoxia for Biomaterials Engineering

Oxygen is essential for normal cellular functions. Hypoxia impacts various cellular processes, such as metabolism, growth, proliferation, angiogenesis, metastasis, tumorigenesis, microbial infection, and immune response, mediated by hypoxia-inducible factors (HIFs). Hypoxia contributes to the progression and development of cancer, cardiovascular diseases, metabolic disorders, kidney diseases, and infections. The potential alleviation of hypoxia has been explored through the enzymatic in situ decomposition of hydrogen peroxide, leading to the generation of oxygen. However, challenges such as limited stability restrict the effectiveness of enzymes such as catalase in biomedical and in vivo applications. To overcome these limitations, targeted delivery of the enzymes has been proposed. This review offers a critical comparison of i) current approaches to enhance the in vivo stability of catalase; and ii) the structure, mechanism of action, and kinetics of catalase and catalase-like nanozymes.

Porous Organic Polymer-Based Nanocomposites for Hypoxia Relieving and Enhanced Chemotherapy in Hepatocellular Carcinoma

Uncontrolled proliferation and altered metabolism of cancer cells result in an imbalance of nutrients and oxygen supply, and persuade hypoxia. Hypoxia, in turn, activates the transcription gene HIF-1α, which eventually upregulates the efflux transporter P-gp and induces multidrug resistance (MDR). Thus, hypoxia leads to the development of resistance to conventional therapies. Therefore, the fabrication of a nanoscale porous system enriched with upconversion nanoparticles to target cancer cells, evade hypoxia, and enhance anticancer therapy is the key goal of this article. Herein, upconversion nanoparticles are embedded in a nanoscale porous organic polymer (POP) and further conjugated with a targeting moiety and a catalase molecule. The nanoscale POP embedded in UCNPs is generated at room temperature. The targeting ligand, lactobionic acid, is attached after polymer coating, which effectively targets liver cancer cells. Then, catalase is grafted effectively to produce oxygen. Endogenously generated oxygen alleviates hypoxia in liver cancer cells. The drug- and catalase-loaded composite exhibit greater cytotoxicity in hypoxic liver cells than in normal cells by overcoming hypoxia and downregulating the hypoxia-inducible factors.

Biochemical hallmarks-targeting antineoplastic nanotherapeutics

Tumor microenvironments (TMEs) have received increasing attention in recent years as they play pivotal roles in tumorigenesis, progression, metastases, and resistance to the traditional modalities of cancer therapy like chemotherapy. With the rapid development of nanotechnology, effective antineoplastic nanotherapeutics targeting the aberrant hallmarks of TMEs have been proposed. The appropriate design and fabrication endow nanomedicines with the abilities for active targeting, TMEs-responsiveness, and optimization of physicochemical properties of tumors, thereby overcoming transport barriers and significantly improving antineoplastic therapeutic benefits. This review begins with the origins and characteristics of TMEs and discusses the latest strategies for modulating the TMEs by focusing on the regulation of biochemical microenvironments, such as tumor acidosis, hypoxia, and dysregulated metabolism. Finally, this review summarizes the challenges in the development of smart anti-cancer nanotherapeutics for TME modulation and examines the promising strategies for combination therapies with traditional treatments for further clinical translation.

A nanomedicine composed of polymer-ss-DOX and polymer-Ce6 prodrugs with monoclonal antibody targeting effect for anti-tumor chemo-photodynamic synergetic therapy

Anticancer drugs used for systemic chemotherapy often exhibit off-target toxicity and uncontrolled drug release due to their lack of targeting. To improve the bioavailability of drugs and reduce side effects, we have developed a mixed micelle of nanomedicine composed of two prodrugs with surface modified monoclonal antibody for cancer therapy. In this system, Nimotuzumab was used as targeting ligands of the mixed micelles (named as DCMMs) that is composed of polymer-doxorubicin prodrug (abbreviated as PEG-b-P(GMA-ss-DOX)) and maleimide polyethylene glycol-chlorin e6 (abbreviated as Mal-PEG-Ce6). The mixed micelles modified with Nimotuzumab (named as NTZ-DCMMs) bind to overexpressed EGFR receptors on Hepatoma-22 (H22) cells. Disulfide bonds in PEG-b-P(GMA-ss-DOX) are disrupted in tumor microenvironment, inducing the reduction-responsive release of DOX and leading to tumor cell apoptosis. Simultaneously, Chlorin e6 (Ce6) produced plenty of singlet oxygen (1O2) under laser irradiation to kill tumor cells. In vivo biological distribution and antineoplastic effect experiments demonstrate that NTZ-DCMMs enhanced drug enrichment at tumor sites through targeting function of antibody, dramatically suppressing tumor growth and mitigating cardiotoxicity of drugs. All results prove that NTZ-DCMMs have the ability to actively target H22 cells and quickly respond to tumor microenvironment, which is expected to become an intelligent and multifunctional drug delivery carrier for efficient chemotherapy and photodynamic therapy of hepatoma. STATEMENT OF SIGNIFICANCE: Anticancer drugs used for systemic chemotherapy often exhibit off-target toxicity due to their lack of targeting. Therefore, it's necessary to develop effective, targeted, and collaborative treatment strategies. We construct a mixed micelle of nanomedicine based on two polymer prodrugs and modified with monoclonal antibody on surface for cancer therapy. Under the tumor cell microenvironment, the disulfide bonds of polymer-ss-DOX were broken, effectively triggering DOX release. The photosensitizer Ce6 could generate a large amount of ROS under light, which synergistically promotes tumor cell apoptosis. By coupling antibodies to the hydrophilic segments of polymer micelles, drugs can be specifically delivered. Compared with monotherapy, the combination of chemotherapy and photodynamic therapy can significantly enhance the therapeutic effect of liver cancer.

Different Targeting Ligands-Mediated Drug Delivery Systems for Tumor Therapy

Traditional tumor treatments have the drawback of harming both tumor cells and normal cells, leading to significant systemic toxic side effects. As a result, there is a pressing need for targeted drug delivery methods that can specifically target cells or tissues. Currently, researchers have made significant progress in developing targeted drug delivery systems for tumor therapy using various targeting ligands. This review aims to summarize recent advancements in targeted drug delivery systems for tumor therapy, focusing on different targeting ligands such as folic acid, carbohydrates, peptides, aptamers, and antibodies. The review also discusses the advantages, challenges, and future prospects of these targeted drug delivery systems.

Strategies to Reverse Hypoxic Tumor Microenvironment for Enhanced Sonodynamic Therapy

Sonodynamic therapy (SDT) has emerged as a highly effective modality for the treatment of malignant tumors owing to its powerful penetration ability, noninvasiveness, site-confined irradiation, and excellent therapeutic efficacy. However, the traditional SDT, which relies on oxygen availability, often fails to generate a satisfactory level of reactive oxygen species because of the widespread issue of hypoxia in the tumor microenvironment of solid tumors. To address this challenge, various approaches are developed to alleviate hypoxia and improve the efficiency of SDT. These strategies aim to either increase oxygen supply or prevent hypoxia exacerbation, thereby enhancing the effectiveness of SDT. In view of this, the current review provides an overview of these strategies and their underlying principles, focusing on the circulation of oxygen from consumption to external supply. The detailed research examples conducted using these strategies in combination with SDT are also discussed. Additionally, this review highlights the future prospects and challenges of the hypoxia-alleviated SDT, along with the key considerations for future clinical applications. These considerations include the development of efficient oxygen delivery systems, the accurate methods for hypoxia detection, and the exploration of combination therapies to optimize SDT outcomes.

An oncolytic system produces oxygen selectively in pancreatic tumor cells to alleviate hypoxia and improve immune activation

INTRODUCTION

Hypoxia is one of the important reasons for the poor therapeutic efficacy of current pancreatic cancer treatment, and the dense stroma of pancreatic cancer restricts the diffusion of oxygen within the tumor.

METHODS

A responsive oxygen-self-supplying adv-miRT-CAT-KR (adv-MCK) cascade reaction system to improve hypoxia in pancreatic cancer is constructed. We utilized various experiments at multiple levels (cells, organoids, in vivo) to investigate its effect on pancreatic cancer and analyzed the role of immune microenvironment changes in it through high-throughput sequencing.

RESULTS

The adv-MCK system is an oncolytic adenovirus system expressing three special components of genes. The microRNA (miRNA) targets (miRTs) enable adv-MCK to selectively replicate in pancreatic cancer cells. Catalase catalyzes the overexpressed hydrogen peroxide in pancreatic cancer cells to generate endogenous oxygen, which is catalyzed by killerRed to generate singlet oxygen (1O2) and further to enhance the oncolytic effect. Meanwhile, the adv-MCK system can specifically improve hypoxia in pancreatic cancer, exert antitumor effects in combination with photodynamic therapy, and activate antitumor immunity, especially by increasing the level of γδ T cells in the tumor microenvironment.

CONCLUSION

The responsive oxygen-self-supplying adv-MCK cascade reaction system combined with photodynamic therapy can improve the hypoxic microenvironment of pancreatic cancer and enhance antitumor immunity, which provides a promising alternative treatment strategy for pancreatic cancer.

Oncofetal reprogramming in tumor development and progression: novel insights into cancer therapy

Emerging evidence indicates that cancer cells can mimic characteristics of embryonic development, promoting their development and progression. Cancer cells share features with embryonic development, characterized by robust proliferation and differentiation regulated by signaling pathways such as Wnt, Notch, hedgehog, and Hippo signaling. In certain phase, these cells also mimic embryonic diapause and fertilized egg implantation to evade treatments or immune elimination and promote metastasis. Additionally, the upregulation of ATP-binding cassette (ABC) transporters, including multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1 (MRP1), and breast cancer-resistant protein (BCRP), in drug-resistant cancer cells, analogous to their role in placental development, may facilitate chemotherapy efflux, further resulting in treatment resistance. In this review, we concentrate on the underlying mechanisms that contribute to tumor development and progression from the perspective of embryonic development, encompassing the dysregulation of developmental signaling pathways, the emergence of dormant cancer cells, immune microenvironment remodeling, and the hyperactivation of ABC transporters. Furthermore, we synthesize and emphasize the connections between cancer hallmarks and embryonic development, offering novel insights for the development of innovative cancer treatment strategies.

Multifunctional Oxygen-Generating Nanoflowers for Enhanced Tumor Therapy

Sonodynamic therapy (SDT) and chemotherapy have received great attention as effective methods for tumor treatment. However, the inherent hypoxia of the tumor greatly hinders its therapeutic efficacy. In this work, a tumor microenvironment-responsive biodegradable nanoplatform SiO2-MnO2-PEG-Ce6&DOX (designated as SMPC&D) is fabricated by encapsulating manganese oxide (MnO2) into silica nanoparticles and anchoring poly(ethylene glycol) (PEG) onto the surface for tumor hypoxia relief and delivery, then loaded with sonosensitizer Chlorin e6 (Ce6) and chemotherapeutic drug doxorubicin (DOX) for hypoxic tumor treatment. We evaluated the physicochemical properties of SMPC&D nanoparticles and the tumor therapeutic effects of chemotherapy and SDT under ultrasound stimulation in vitro and in vivo. After endocytosis by tumor cells, highly expressed glutathione (GSH) triggers biodegradation of the nanoplatform and MnO2 catalyzes hydrogen peroxide (H2O2) to generate oxygen (O2), thereby alleviating tumor hypoxia. Depleting GSH and self-supplying O2 effectively improve the SDT efficiency both in vitro and in vivo. Ultrasonic stimulation promoted the release and cellular uptake of chemotherapy drugs. In addition, the relieved hypoxia reduced the efflux of chemotherapy drugs by downregulating the expression of the P-gp protein, which jointly improved the effect of chemotherapy. This study demonstrates that the degradable SMPC&D as a therapeutic agent can achieve efficient chemotherapy and SDT synergistic therapy for hypoxic tumors.

An Oxygen Supply Strategy for Sonodynamic Therapy in Tuberculous Granuloma Lesions Using a Catalase-Loaded Nanoplatform

Purpose

Tuberculosis (TB) is a chronic disease caused by Mycobacterium tuberculosis (MTB) that remains a major global health challenge. One of the main obstacles to effective treatment is the heterogeneous microenvironment of TB granulomas. This study aimed to investigate the potential of a hypoxic remission-based strategy to enhance the outcome of tuberculosis treatment when implemented in combination with ultrasound.

Methods

A PLGA nanoparticle (LEV@CAT-NPs) loaded with levofloxacin (LEV) and catalase (CAT) was fabricated by a double emulsification method, and its physical characteristics, oxygen production capacity, drug release capacity, and biosafety were thoroughly investigated. The synergistic therapeutic effects of ultrasound (US)-mediated LEV@CAT-NPs were evaluated using an experimental mouse model of subcutaneous tuberculosis granuloma induced by Bacille Calmette-Guérin (BCG) as a substitute for MTB.

Results

LEV@CAT-NPs exhibited excellent oxygen production capacity, biosafety, and biocompatibility. Histological analysis revealed that ultrasound-mediated LEV@CAT-NPs could effectively remove bacteria from tuberculous granulomas, significantly alleviate the hypoxia state, reduce the necrotic area and inflammatory cells within the granuloma, and increase the penetration of dyes in granuloma tissues. The combined treatment also reduced the serum levels of inflammatory cytokines (eg, TNF-α, IL-6, and IL-8), and significantly downregulated the expression of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF). These results suggested that the synergistic treatment of ultrasound-mediated LEV@CAT-NPs effectively eradicated the bacterial infection and reversed the hypoxic microenvironment of tuberculous granulomas, further promoting tissue repair.

Conclusion

This study provides a non-invasive and new avenue for treating refractory tuberculosis infections. The potential role of regulating hypoxia within infected lesions as a therapeutic target for infection deserves further exploration in future studies.

Multifunctional protein-based self-assembled nanoplatform: overcoming hypoxic tumor microenvironment for enhanced imaging-guided photodynamic therapy

Photodynamic therapy (PDT) has emerged as a promising modality for cancer treatment, but its efficacy is often limited by tumour hypoxia. Here, we report the development of a novel protein-based, self-assembled nanoplatform, CAT-I-BODIPY NPs (CIB NPs), to address this limitation. We first design and synthesize an I-BODIPY photosensitizer based on the heavy atom effect and modification of the electron-donating group, which exhibits excellent capabilities in generating reactive oxygen species and enabling near-infrared (NIR) fluorescence imaging. The incorporation of an oxygen-producing enzyme, catalase (CAT), within these nanoassemblies enables in situ oxygen generation to counteract hypoxic constraints. Controllable self-assembly by multiple supramolecular interactions into highly ordered architecture not only guarantees CAT's catalytic activity but also leads to excellent NIR fluorescence imaging ability and enhanced PDT efficacy. Notably, the visualization of optimal accumulation of CIB NPs within tumour sites 18 h post-injection offers precise PDT application guidance. Both in vitro and in vivo studies corroborate the remarkable anti-tumour efficacy of CIB NPs under NIR illumination, providing a significant advancement in PDT. The favourable biosafety profile of CIB NPs further emphasizes their potential for clinical application in hypoxic tumour therapy.

M1 Macrophage-Biomimetic Targeted Nanoparticles Containing Oxygen Self-Supplied Enzyme for Enhancing the Chemotherapy

Tumor hypoxia is considered one of the key causes of the ineffectiveness of various strategies for cancer treatment, and the non-specific effects of chemotherapy drugs on tumor treatment often lead to systemic toxicity. Thus, we designed M1 macrophage-biomimetic-targeted nanoparticles (DOX/CAT@PLGA-M1) which contain oxygen self-supplied enzyme (catalase, CAT) and chemo-therapeutic drug (doxorubicin, DOX). The particle size of DOX/CAT@PLGA-M1 was 202.32 ± 2.27 nm (PDI < 0.3). DOX/CAT@PLGA-M1 exhibited a characteristic core-shell bilayer membrane structure. The CAT activity of DOX/CAT@PLGA-M1 was 1000 (U/mL), which indicated that the formation of NPs did not significantly affect its enzymatic activity. And in vitro drug release showed that the cumulative release rate of DOX/CAT@PLGA-M1 was enhanced from 26.93% to 50.10% in the release medium of hydrogen peroxide, which was attributed to the reaction of CAT in the NPs. DOX/CAT@PLGA-M1 displayed a significantly higher uptake in 4T1 cells, because VCAM-1 in tumor cells interacted with specific integrin (α4 and β1), and thereby achieved tumor sites. And the tumor volume of the DOX/CAT@PLGA-M1 group was significantly reduced (0.22 cm3), which further proved the active targeting effect of the M1 macrophage membrane. Above all, a novel multifunctional nano-therapy was developed which improved tumor hypoxia and obtained tumor targeting activity.

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.

Ultra-sensitive detection of 5-fluorouracil by flow injection chemiluminescence immunoassay based on Fenton-like effect of single atom Co nanozyme

Single atom nanozymes (SAzymes) are considered as the most hopeful candidates for replacing natural enzymes. In this work, a flow-injection chemiluminescent immunoassay (FI-CLIA) based on a Fenton-like activity single atom cobalt nanozyme (Co SAzyme) was developed for the rapid and sensitive detection of 5-fluorouracil (5-Fu) in serum for the first time. Co SAzyme was prepared by an in-situ etching method at room temperature using ZIF-8 metal-organic frameworks (ZIF-8 MOFs). With excellent chemical stability and ultra-high porosity of ZIF-8 MOFs as the core, Co SAzyme presents high Fenton-like activity which can catalyze the decomposition of H₂O₂ to produce large amounts of superoxide radical anions, thus effectively amplifying the chemiluminescence of the Luminol-H₂O₂ system. In addition, carboxyl-modified resin beads were used as the substrate to load more antigens due to its advantages of good biocompatibility and large specific surface area. Under optimal conditions, the detection range of 5-Fu was 0.001-1000 ng mL^-1 with a limit of detection of 0.29 pg mL^-1 (S/N = 3). Furthermore, the immunosensor was successfully applied for the detection of 5-Fu in human serum samples with satisfactory results, displaying the potential application of this strategy for bioanalysis and clinical diagnosis.

Tumor-localized catalases can fail to alter tumor growth and transcriptional profiles in subcutaneous syngeneic mouse tumor models

Catalase is an antioxidant enzyme that catalyzes the rapid conversion of hydrogen peroxide to water and oxygen. Use of catalase as a cancer therapeutic has been proposed to reduce oxidative stress and hypoxia in the tumor microenvironment, both activities which are hypothesized to reduce tumor growth. Furthermore, exposing murine tumors to exogenous catalase was previously reported to have therapeutic benefit. We studied the therapeutic effect of tumor-localized catalases with the aim to further elucidate the mechanism of action. To do this, we engineered two approaches to maximize intratumoral catalase exposure: 1) an injected extracellular catalase with enhanced tumor retention, and 2) tumor cell lines that over-express intracellular catalase. Both approaches were characterized for functionality and tested for therapeutic efficacy and mechanism in 4T1 and CT26 murine syngeneic tumor models. The injected catalase was confirmed to have enzyme activity >30,000 U/mg and was retained at the injection site for more than one week in vivo. The engineered cell lines exhibited increased catalase activity and antioxidant capacity, with catalase over-expression that was maintained for at least one week after gene expression was induced in vivo. We did not observe a significant difference in tumor growth or survival between catalase-treated and untreated mice when either approach was used. Finally, bulk RNA sequencing of tumors was performed, comparing the gene expression of catalase-treated and untreated tumors. Gene expression analysis revealed very few differentially expressed genes as a result of exposure to catalase and notably, we did not observe changes consistent with an altered state of hypoxia or oxidative stress. In conclusion, we observe that sustained intratumoral catalase neither has therapeutic benefit nor triggers significant differential expression of genes associated with the anticipated therapeutic mechanism in the subcutaneous syngeneic tumor models used. Given the lack of effect observed, we propose that further development of catalase as a cancer therapeutic should take these findings into consideration.

Inhibition of melanoma using a nanoceria-based prolonged oxygen-generating phototherapy hydrogel

Tumor hypoxic environment is an inevitable obstacle for photodynamic therapy (PDT) of melanoma. Herein, a multifunctional oxygen-generating hydrogel loaded with hyaluronic acid-chlorin e6 modified nanoceria and calcium peroxide (Gel-HCeC-CaO2) was developed for the phototherapy of melanoma. The thermo-sensitive hydrogel could act as a sustained drug delivery system to accumulate photosensitizers (chlorin e6, Ce6) around the tumor, followed by cellular uptake mediated by nanocarrier and hyaluronic acid (HA) targeting. The moderate sustained oxygen generation in the hydrogel was produced by the reaction of calcium peroxide (CaO2) with infiltrated H2O in the presence of catalase mimetic nanoceria. The developed Gel-HCeC-CaO2 could efficiently alleviate the hypoxia microenvironment of tumors as indicated by the expression of hypoxia-inducible factor -1α (HIF-1α), meeting the “once injection, repeat irradiation” strategy and enhanced PDT efficacy. The prolonged oxygen-generating phototherapy hydrogel system provided a new strategy for tumor hypoxia alleviation and PDT.

Carbohydrate ligands-directed active tumor targeting of combinatorial chemotherapy/phototherapy-based nanomedicine: A review

Phototherapies or light mediated therapies, including mutually photothermal and photodynamic therapy that encompass irradiation of the target organs with light, have been widely employed as minimally invasive approach associated with negligible drug resistance for eradicating multiple tumors with minimal hazards to normal organs. Despite all these advantages, many obstacles in phototherapy hinder progress toward clinical application. Therefore, researchers have developed nano-particulate delivery systems integrated with phototherapy and therapeutic cytotoxic drugs to overcome these obstacles and achieve maximum efficacy in cancer treatment. Active targeting ligands were integrated into their surfaces to improve the selectivity and tumor targeting ability, enabling easy binding and recognition by cellular receptors overexpressed on the tumor tissue compared to normal ones. This enhances intratumoral accumulation with minimal toxicity on the adjacent normal cells. Various active targeting ligands, including antibodies, aptamers, peptides, lactoferrin, folic acid and carbohydrates, have been explored for the targeted delivery of chemotherapy/phototherapy-based nanomedicine. Among these ligands, carbohydrates have been applied due to their unique features that ameliorate the bioadhesive, noncovalent conjugation to biological tissues. In this review, the up-to-date techniques of employing carbohydrates active targeting ligands will be highlighted concerning the surface modification of the nanoparticles for ameliorating the targeting ability of the chemo/phototherapy.

Anti-Hypoxia Nanoplatforms for Enhanced Photosensitizer Uptake and Photodynamic Therapy Effects in Cancer Cells

Photodynamic therapy (PDT) holds great promise in cancer eradication due to its target selectivity, non-invasiveness, and low systemic toxicity. However, due to the hypoxic nature of many native tumors, PDT is frequently limited in its therapeutic effect. Additionally, oxygen consumption during PDT may exacerbate the tumor's hypoxic condition, which stimulates tumor proliferation, metastasis, and invasion, resulting in poor treatment outcomes. Therefore, various strategies have been developed to combat hypoxia in PDT, such as oxygen carriers, reactive oxygen supplements, and the modulation of tumor microenvironments. However, most PDT-related studies are still conducted on two-dimensional (2D) cell cultures, which fail to accurately reflect tissue complexity. Thus, three-dimensional (3D) cell cultures are ideal models for drug screening, disease simulation and targeted cancer therapy, since they accurately replicate the tumor tissue architecture and microenvironment. This review summarizes recent advances in the development of strategies to overcome tumor hypoxia for enhanced PDT efficiency, with a particular focus on nanoparticle-based photosensitizer (PS) delivery systems, as well as the advantages of 3D cell cultures.

Multifunctional Nanoparticles Codelivering Doxorubicin and Amorphous Calcium Carbonate Preloaded with Indocyanine Green for Enhanced Chemo-Photothermal Cancer Therapy

Background

Multifunctional stimuli-responsive nanoparticles with photothermal-chemotherapy provided a powerful tool for improving the accuracy and efficiency in the treatment of malignant tumors.

Methods

Herein, photosensitizer indocyanine green (ICG)-loaded amorphous calcium-carbonate (ICG@) nanoparticle was prepared by a gas diffusion reaction. Doxorubicin (DOX) and ICG@ were simultaneously encapsulated into poly(lactic-co-glycolic acid)-ss-chondroitin sulfate A (PSC) nanoparticles by a film hydration method. The obtained PSC/ICG@+DOX hybrid nanoparticles were characterized and evaluated by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The cellular uptake and cytotoxicity of PSC/ICG@+DOX nanoparticles were analyzed by confocal laser scanning microscopy (CLSM) and MTT assay in 4T1 cells. In vivo antitumor activity of the nanoparticles was evaluated in 4T1-bearing Balb/c mice.

Results

PSC/ICG@+DOX nanoparticles were nearly spherical in shape by TEM observation, and the diameter was 407 nm determined by DLS. Owing to calcium carbonate and disulfide bond linked copolymer, PSC/ICG@+DOX nanoparticles exhibited pH and reduction-sensitive drug release. Further, PSC/ICG@+DOX nanoparticles showed an effective photothermal effect under near-infrared (NIR) laser irradiation, and improved cellular uptake and cytotoxicity in breast cancer 4T1 cells. Importantly, PSC/ICG@+DOX nanoparticles demonstrated the most effective suppression of tumor growth in orthotopic 4T1-bearing mice among the treatment groups. In contrast with single chemotherapy or photothermal therapy, chemo-photothermal treatment by PSC/ICG@+DOX nanoparticles synergistically inhibited the growth of 4T1 cells.

Conclusion

This study demonstrated that PSC/ICG@+DOX nanoparticles with active targeting and stimuli-sensitivity would be a promising strategy to enhance chemo-photothermal cancer therapy.

A copper nanocluster-based multifunctional nanoplatform for augmented chemo/chemodynamic/photodynamic combination therapy of breast cancer

With the development of nano drug delivery system, the treatment mode that can overcome the shortcomings of chemotherapy drugs and integrate combined therapy remains to be explored. Herein, a nano drug system was designed to achieve the combined effect of chemo/chemodynamic/photodynamic therapy on cancer. Specifically, copper clusters (CuNCs) were used as the carrier, hyaluronic acid (HA) and doxorubicin (DOX) were coupled on CuNCs and then and chlorin e6 (Ce6) was introduced to form the self-assembled HA-CuNCs@DC nanoparticles. In this system, the HA-CuNCs@DC was involved in the reaction to the acidic tumor microenvironment (TME)-release of DOX, which could not only inhibit tumor growth through chemotherapy, but enhance the generation of hydrogen peroxide. CuNCs carriers had the properties of Fenton-like activity to realize chemodynamic therapy (CDT) and oxidase-like activity to deplete intracellular glutathione (GSH). Additionally, the chemotherapy drug susceptibility increased owing to the GSH depletion and the outbreak of reactive oxygen species, indicating the enhanced CDT efficacy and amplified chemotherapy efficacy. It was also noteworthy that Ce6 could be activated by 660 nm light to produce abundant singlet oxygen for photodynamic therapy. Overall, our platform demonstrated excellent biosafety and tumor suppression capabilities. This multimodal theranostic strategy provided new insights into cancer therapy.

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.

Biomedical engineered nanomaterials to alleviate tumor hypoxia for enhanced photodynamic therapy

Photodynamic therapy (PDT), as a highly selective, widely applicable, and non-invasive therapeutic modality that is an alternative to radiotherapy and chemotherapy, is extensively applied to cancer therapy. Practically, the efficiency of PDT is severely hindered by the existence of hypoxia in tumor tissue. Hypoxia is a typical hallmark of malignant solid tumors, which remains an essential impediment to many current treatments, thereby leading to poor clinical prognosis after therapy. To address this issue, studies have been focused on modulating tumor hypoxia to augment the therapeutic efficacy. Although nanomaterials to relieve tumor hypoxia for enhanced PDT have been demonstrated in many research articles, a systematical summary of the role of nanomaterials in alleviating tumor hypoxia is scarce. In this review, we introduced the mechanism of PDT, and the involved therapeutic modality of PDT for ablation of tumor cells was specifically summarized. Moreover, current advances in nanomaterials-mediated tumor oxygenation via oxygen-carrying or oxygen-generation tactics to alleviate tumor hypoxia are emphasized. Based on these considerable summaries and analyses, we proposed some feasible perspectives on nanoparticle-based tumor oxygenation to ameliorate the therapeutic outcomes, which may provide some detailed information in designing new oxygenation nanomaterials in this burgeneous field.

Nanomaterials-mediated photodynamic therapy and its applications in treating oral diseases

Oral diseases, such as dental caries, periodontitis and oral cancer, have a very high morbidity over the world. Basically, many oral diseases are commonly related to bacterial infections or cell malignant proliferation, and usually located on the superficial positions. These features allow the convenient and efficient application of photodynamic therapy (PDT) for oral diseases, since PDT is ideally suitable for the diseases on superficial sites and has been widely used for antimicrobial and anticancer therapy. Photosensitizers (PSs) are an essential element in PDT, which induce the generation of a large number of reactive oxygen species (ROS) upon absorption of specific lights. Almost all the PSs are small molecules and commonly suffered from various problems in the PDT environment, such as low solubility and poor stability. Recently, reports on the nanomedicine-based PDT have been well documented. Various functionalized nanomaterials can serve either as the PSs carriers or the direct PSs, thus enhancing the PDT efficacy. Herein, we aim to provide a comprehensive understanding of the features of different oral diseases and discuss the potential applications of nanomedicine-based PDT in the treatment of some common oral diseases. Also, the concerns and possible solutions for nanomaterials-mediated PDT are discussed.

Targeted co-delivery of a photosensitizer and an antisense oligonucleotide based on an activatable hyaluronic acid nanosystem with endogenous oxygen generation for enhanced photodynamic therapy of hypoxic tumors

Photodynamic therapy (PDT) is a promising cancer treatment modality with advantages of minimal invasiveness, repeatable therapy, and mild systemic toxicity. However, the limited bioavailability of photosensitizer (PS), tumor hypoxia, and the presence of antiapoptotic proteins in cancer cells, has hampered the efficiency of PDT. To address these limitations, herein, we developed a hyaluronic acid (HA) based nanosystem (HA-Ce6-Hemin@DNA-Protamine NPs, HCH@DP) loaded with chlorin e6 (Ce6, as PS), hemin (as mimetic catalase) and antisense oligonucleotide (ASO) of B-cell lymphoma 2 (Bcl-2) anti-apoptosis protein via a simple electrostatic self-assembly method for enhanced PDT of hypoxic solid tumors. The HCH@DP can target deliver the PS and ASO to tumor cells via cancer cell overexpressed HA receptors (i.e., CD44 or RHAMM). The Ce6 was released from HA-ss-Ce6 (HSC conjugates) after the reaction of cleavable disulfide bond with glutathione (GSH), which recovered the fluorescence and phototoxicity of Ce6 upon laser irradiation. Meanwhile, the catalase-mimicking hemin (degradation of HA-eda-hemin by hyaluronidase) decomposed the tumor overdressed endogenous H₂O₂ to oxygen, which relieved tumor hypoxia and further overcome hypoxia-associated resistance of PDT. Furthermore, the inhibition of Bcl-2 expression by Bcl-2 ASO also greatly improved the cellular sensitivity to PDT. Both in vitro and in vivo results showed the tumor cell targeting ability, hypoxia relief and significantly enhanced antitumor PDT efficacy of HCH@DP for hypoxic tumor cells upon laser irradiation. Thus, by improving the target delivery of PS and ASO, relieving tumor hypoxia, and down-regulation of anti-apoptotic proteins, this HCH@DP nanosystem achieved enhanced PDT efficiency against hypoxic tumors. In general, our work provided a promising strategy to increase the utilization of key components (PS and oxygen) of PDT and the cell sensitivity to PDT by targeting co-delivery PS and oligonucleotides to tumor cells via a biocompatible HA based carrier, thereby achieving efficiently PDT treatment of hypoxic solid tumors with potential translation possibility. STATEMENT OF SIGNIFICANCE: The efficiency of PDT against solid tumor is severely restricted by the limited bioavailability of photosensitizer, tumor hypoxia, and the presence of antiapoptotic proteins in cancer cells. Herein, we have developed an activatable hyaluronic acid (HA) based nanosystem (HA-Ce6-Hemin@DNA-Protamine NPs, HCH@DP) via a simple electrostatic self-assembly method for PDT treatment of hypoxic solid tumors. The HCH@DP enabled to target co-delivery of photosensitizer and antisense oligonucleotide to tumor cells, overcoming tumor hypoxia through in situ oxygen production and improving cellular sensitivity by efficiently reducing anti-apoptosis effect of cancer cells for synergistically enhancing PDT efficiency. This work suggests a promising strategy to develop small molecule drug and oligonucleotides co-delivery nanoplatforms for efficiently PDT treatment of hypoxic solid tumor.

Hemin-loaded black phosphorus-based nanosystem for enhanced photodynamic therapy and a synergistic photothermally/photodynamically activated inflammatory immune response

The biocompatible nanosystem integrating hemin into black phosphorus nanosheets was ingeniously constructed through the easy modified strategy. Taking advantage of the enhanced permeability and retention (EPR) effect, the designed nanosystem could accumulate into the tumor location, leading to attractive cytotoxicity through the enhanced photodynamic therapy (PDT) ascribing to the catalytic oxygen supply and GSH depletion of hemin. Simultaneously, combining PDT and photothermal therapy (PTT) showed an apparent promotion in anti-tumor effect. Moreover, inflammatory response and immune activation amplified anti-tumor effect, which could compensate limitations of exogenous therapy (i.e., limited tissue depth and intensity-dependent curation effect) and potentiate the efficiency of the endogenous immune-activating behavior. Especially, the designed nanosystem degraded followed by being metabolized in the blood circulation. By and large, this constructed nanosystem provides the new insight into designing biocompatible nanomaterials and paves the ideal way for anti-tumor therapy. STATEMENT OF SIGNIFICANCE: Biocompatible nanomaterials-based synergistic tumor therapy offers the potential application prospect. Taking advantage of degradable black phosphorus, the nanosystem integrating hemin into black phosphorus for the enhanced photodynamic therapy and synergistic photothermal-photodynamic activating inflammation-immune response was developed and the results demonstrate that tumor growth was inhibited followed by activating inflammatory factors and leading to satisfactory immune response.

Thiolated hyaluronic acid and catalase-enhanced CD44-targeting and oxygen self-supplying nanoplatforms with photothermal/photodynamic effects against hypoxic breast cancer cells

Photothermal and photodynamic therapies (PTT/PDT) have been widely accepted as noninvasive therapeutic methods for cancer treatment. However, tumor hypoxia and insufficient delivery of photoactive compounds to cancer cells can reduce the efficacy of phototherapy. Herein, we first synthesized thiolated hyaluronic acid (THA) and then conjugated it with catalase (CAT) onto chlorin e6 (Ce6)-adsorbed small gold nanorods (Ce6@sAuNRs) with near-infrared (NIR)/visible light activated photothermal/photodynamic effects. The conjugation of THA and CAT on Ce6@sAuNRs resulted in a red-shift of the longitudinal LSPR absorption band of sAuNRs up to 1000 nm and maintained the excellent enzymatic activity of catalase. Modification of Ce6@sAuNRs with THA resulted in efficient internalization of the nanocomposite into MCF-7/ADR multidrug-resistant (MDR) breast cancer cells (CD44+), thereby significantly enhancing the intracellular accumulation of the photosensitizer Ce6. CAT endows Ce6@sAuNRs with self-supporting oxygen production, which enables them to efficiently generate singlet oxygen (¹O₂) under 660 nm laser irradiation and enhances the photodynamic effect against hypoxic breast cancer cells. The results highlight the prospect of this novel multi-functional nanoplatform integrating active biological macromolecules (THA and CAT) into photosensitizer/photothermal gold nanocomposites in overcoming the limitations of hypoxic MDR breast cancer cell treatment.

Tumor microenvironment-responsive nanohybrid for hypoxia amelioration with photodynamic and near-infrared II photothermal combination therapy

Phototherapy, particularly photothermal therapy (PTT) and photodynamic therapy (PDT), has been widely investigated for tumor treatment. However, the limited tissue penetration depth of light in the near-infrared I (NIR-I) region and the hypoxic tumor microenvironment (TME) severely constrain their clinical applications. To address these challenges, in the present study, we developed a chlorin e6 (Ce6) and MnO₂-coloaded, hyaluronic acid (HA)-coated single-walled carbon nanohorns (SWNHs) nanohybrid (HA-Ce6-MnO₂@SWNHs) for PDT and PTT combination therapy of tumor. HA-Ce6-MnO₂@SWNHs responded to the mild acidic TME to ameliorate tumor hypoxia, thus enhancing tumor PDT. Moreover, HA-Ce6-MnO₂@SWNHs had a high photothermal conversion efficiency at 1064 nm (55.48%), which enabled deep tissue penetration (3.05 cm) and allowed for highly efficient tumor PTT in near-infrared II (NIR-II) window. PDT and PTT combination therapy with HA-Ce6-MnO₂@SWNHs achieved a good therapeutic efficacy on 4T1 tumor-bearing mice, eradicating the primary tumors and suppressing cancer recurrence. Our study provides a promising strategy for developing a hypoxia relief and deep tissue penetration phototherapy platform by using SWNHs for highly effective tumor PDT and NIR-II PTT combination therapy. STATEMENT OF SIGNIFICANCE: The hypoxic tumor microenvironment (TME) and the limited penetration of the NIR-I light in biological tissues compromise the efficacy of photothermal therapy (PTT) and photodynamic therapy (PDT) on tumors. Here, we developed a chlorin e6 (Ce6) and MnO₂-coloaded, hyaluronic acid (HA)-coated single-walled carbon nanohorns (SWNHs) nanohybrid (HA-Ce6-MnO₂@SWNHs) for PDT and PTT combination therapy of tumors. The nanohybrid could efficiently accumulate in tumors through CD44-mediated active targeting. The sequential MnO₂-enhanced PDT and efficient NIR-II PTT had a remarkable therapeutic effect by eliminating the primary tumor and simultaneously inhibiting tumor recurrence.

The strategy of precise targeting and in situ oxygenating for enhanced triple-negative breast cancer chemophototherapy

The absence of effective therapeutic targets and tumor hypoxia are the main causes of failure in the treatment of triple-negative breast cancer (TNBC). Biomimetic nanotechnology and tumor microenvironment (TME) responsiveness bring hope and opportunity to address this problem. Here, we develop a core membrane nanoplatform (HM/D-I-BL) using hollow mesoporous manganese dioxide (HM) coated with a biomimetic cancer cell membrane for enhanced chemotherapy/phototherapy via the strategy of precise drug delivery and hypoxia amelioration. Cancer cell membrane modification endows HM/D-I-BL with excellent homologous targeting and immune escape performance. Cellular uptake and fluorescence imaging studies confirmed that HM/D-I-BL can be accurately delivered to tumor sites. HM/D-I-BL also features efficient in situ O₂ generation in tumors upon laser irradiation, and subsequently enhanced chemotherapy/phototherapy, pointing to its usefulness as a TME-responsive nanozyme to alleviate tumor hypoxia in the presence of H₂O₂. In addition, HM/D-I-BL showed good fluorescence and magnetic resonance imaging performances, which offers a reliable multimodal image-guided combination tumor therapy for precision theranostics in the future. In general, this intelligent biomimetic nanoplatform with its homotypic tumor targeting, in situ alleviation of tumor hypoxia and synergetic chemophototherapy would open up a new dimension for the precision treatment of TNBC.

Self-Assembly Catalase Nanocomplex Conveyed by Bacterial Vesicles for Oxygenated Photodynamic Therapy and Tumor Immunotherapy

Background

Photodynamic therapy (PDT) is an effective therapeutic modality that has been extensively studied in treatment of various cancers. However, issues with inadequate oxygen (O₂) concentration in tumor tissue and inadequate immune response generation have hindered its successful application in tumor therapy.

Methods

Firstly, the self-assembly nanocomplex (CAT-Ce6), which is composed of hydrophilic catalase and hydrophobic photosensitizer Chlorin e6 (Ce6), was fabricated to support oxygenated PDT. Secondly, for supplying PDT with enhanced antitumoral immunity, CAT-Ce6 was coated with PD-L1 antibody modified-attenuated Salmonella outer membrane vesicles (OMV-aPDL1). Finally, the catalytic activity, tumor targeting, hypoxia ameliorating, immune effect initiating and anti-tumor capacities of the integral nanosystem CAT-Ce6@OMV-aPDL1 were evaluated systematically.

Results

The self-assembly nanocomplex (CAT-Ce6) generated sufficient O₂ and promoted the solubility of Ce6 simultaneously, which enhanced PDT significantly. OMV-aPDL1 inherited most of the immunogenic membrane-associated components from the parent bacteria, possessing immunomodulation ability for immunosuppressive tumor microenvironment reprogramming and reducing immune escape. The obtained nanosystem CAT-Ce6@OMV-aPDL1 durably relieved hypoxia, resulting in amplifying PDT-mediated cytotoxicity to generate a pool of tumor-associated antigens, stimulating anti-tumor immune responses and even inducing an immune memory effect, which inhibited tumor development efficiently.

Conclusion

The resultant CAT-Ce6@OMV-aPDL1 displays excellent efficacy of PDT and immunotherapy to achieve antitumor effects, which provides a new avenue for combinatorial therapy against various cancers.

Hybrid-Membrane-Decorated Prussian Blue for Effective Cancer Immunotherapy via Tumor-Associated Macrophages Polarization and Hypoxia Relief

Both tumor-associated macrophages (TAMs) and hypoxia condition severely restrict the antitumor potency during cancer immunotherapy. It is essential to overcome the two issues for improving therapeutic efficacy. In this study, a hollow mesoporous Prussian blue (HMPB) nanosystem with mannose decoration and hydroxychloroquine (HCQ) adsorption is built, to form Man-HMPB/HCQ. It can facilitate cellular internalization via mannose-receptor mediated endocytosis and induce TAM polarization via iron ion/HCQ release with HMPB degradation. The hybrid macrophage and thylakoid (TK) membrane is camouflaged on the Man-HMPB/HCQ surface, denoted as TK-M@Man-HMPB/HCQ, to reduce in vivo reticuloendothelial system uptake, enhance tumor accumulation, and mitigate hypoxia. The in vivo results indicate that TK-M@Man-HMPB/HCQ notably inhibits tumor growth, induces TAM polarization, facilitates cytotoxic T lymphocytes infiltration, and alleviates hypoxia microenvironment. The rational design may provide a new pathway to modulate the tumor microenvironment for promoting cancer immunotherapy effects.

Bioenzyme-based nanomedicines for enhanced cancer therapy

Bioenzymes that catalyze reactions within living systems show a great promise for cancer therapy, particularly when they are integrated with nanoparticles to improve their accumulation into tumor sites. Nanomedicines can deliver toxic bioenzymes into cancer cells to directly cause their death for cancer treatment. By modulating the tumor microenvironment, such as pH, glucose concentration, hypoxia, redox levels and heat shock protein expression, bioenzyme-based nanomedicines play crucial roles in improving the therapeutic efficacy of treatments. Moreover, bioenzyme-mediated degradation of the major components in tumor extracellular matrix greatly increases the penetration and retention of nanoparticles in deep tumors and infiltration of immune cells into tumor tissues, thus enhancing the efficacies of chemotherapy, phototherapy and immunotherapy. In this review, we summarize the recent progresses of bioenzyme-based nanomedicines for enhanced cancer therapy. The design and working mechanisms of the bioenzyme-based nanomedicines to achieve enhanced chemotherapy, photothermal therapy, photodynamic therapy, chemodynamic therapy, radiotherapy and immunotherapy are introduced in detail. At the end of this review, a conclusion and current challenges and perspectives in this field are given.

Enhanced photodynamic therapy/photothermotherapy for nasopharyngeal carcinoma via a tumour microenvironment-responsive self-oxygenated drug delivery system

The hypoxic nature of tumours limits the efficiency of oxygen-dependent photodynamic therapy (PDT). Hence, in this study, indocyanine green (ICG)-loaded lipid-coated zinc peroxide (ZnO₂) nanoparticles (ZnO₂@Lip-ICG) was constructed to realize tumour microenvironment (TME)-responsive self-oxygen supply. Near infrared light irradiation (808 nm), the lipid outer layer of ICG acquires sufficient energy to produce heat, thereby elevating the localised temperature, which results in accelerated ZnO₂ release and apoptosis of tumour cells. The ZnO₂ rapidly generates O₂ in the TME (pH 6.5), which alleviates tumour hypoxia and then enhances the PDT effect of ICG. These results demonstrate that ZnO₂@Lip-ICG NPs display good oxygen self-supported properties and outstanding PDT/PTT characteristics, and thus, achieve good tumour proliferation suppression.

Engineering nanomedicines to inhibit hypoxia-inducible Factor-1 for cancer therapy

Hypoxia-inducible factor-1 (HIF-1), an essential promoter of tumor progression, has attracted increasing attention as a therapeutic target. In addition to hypoxic cellular conditions, HIF-1 activation can be triggered by cancer treatment, which causes drug tolerance and therapeutic failure. To date, a series of effective strategies have been explored to suppress HIF-1 function, including silencing the HIF-1α gene, inhibiting HIF-1α protein translation, degrading HIF-1α protein, and inhibiting HIF-1 transcription. Furthermore, nanoparticle-based drug delivery systems have been widely developed to improve the stability and pharmacokinetics of HIF-1 inhibitors or achieve HIF-1-targeted combination therapies as a nanoplatform. In this review, we summarize the current literature on nanomedicines targeting HIF-1 to combat cancer and discuss their potential for future development.

Recent Advances in Strategies for Addressing Hypoxia in Tumor Photodynamic Therapy

Photodynamic therapy (PDT) is a treatment modality that uses light to target tumors and minimize damage to normal tissues. It offers advantages including high spatiotemporal selectivity, low side effects, and maximal preservation of tissue functions. However, the PDT efficiency is severely impeded by the hypoxic feature of tumors. Moreover, hypoxia may promote tumor metastasis and tumor resistance to multiple therapies. Therefore, addressing tumor hypoxia to improve PDT efficacy has been the focus of antitumor treatment, and research on this theme is continuously emerging. In this review, we summarize state-of-the-art advances in strategies for overcoming hypoxia in tumor PDTs, categorizing them into oxygen-independent phototherapy, oxygen-economizing PDT, and oxygen-supplementing PDT. Moreover, we highlight strategies possessing intriguing advantages such as exceedingly high PDT efficiency and high novelty, analyze the strengths and shortcomings of different methods, and envision the opportunities and challenges for future research.

Combinatorial Therapeutic Approaches with Nanomaterial-Based Photodynamic Cancer Therapy

Photodynamic therapy (PDT), in which a light source is used in combination with a photosensitizer to induce local cell death, has shown great promise in therapeutically targeting primary tumors with negligible toxicity and minimal invasiveness. However, numerous studies have shown that noninvasive PDT alone is not sufficient to completely ablate tumors in deep tissues, due to its inherent shortcomings. Therefore, depending on the characteristics and type of tumor, PDT can be combined with surgery, radiotherapy, immunomodulators, chemotherapy, and/or targeted therapy, preferably in a patient-tailored manner. Nanoparticles are attractive delivery vehicles that can overcome the shortcomings of traditional photosensitizers, as well as enable the codelivery of multiple therapeutic drugs in a spatiotemporally controlled manner. Nanotechnology-based combination strategies have provided inspiration to improve the anticancer effects of PDT. Here, we briefly introduce the mechanism of PDT and summarize the photosensitizers that have been tested preclinically for various cancer types and clinically approved for cancer treatment. Moreover, we discuss the current challenges facing the combination of PDT and multiple cancer treatment options, and we highlight the opportunities of nanoparticle-based PDT in cancer therapies.

Enzyme-Loaded Catalytic Macrophage Vesicles with Cascade Amplification of Tumor-Targeting for Oxygenated Photodynamic Therapy

Background

Realizing that the potential of photodynamic therapy (PDT) is hindered by hypoxic microenvironment of tumor section, it is desirable to provide a cascade oxygenation strategy to enhance PDT.

Methods

The hydrophilic catalase protein was covalently linked to the hydrophobic photosensitizer Ce6 to form the nanocomplex Catalase-Ce6 with self-assembly. And the Catalase-Ce6 was loaded in the M1 macrophage vesicles (EVs) with GOX-modified to construct the nanosystem Catalase-Ce6@MEVs. The synergistic effects of PDT induced by Catalase-Ce6@MEVs were evaluated on the subcutaneous MFC tumor model.

Results

The construction of Catalase-Ce6 not only solved the insoluble problem of Ce6, but also induced a cascade effects for hydrolyzing glucose and increasing the hydrogen peroxide content, achieving the purpose of oxygenated PDT. Cascade tumor targeting was also realized through the binding between vascular cell adhesion molecule 1 (VCAM-1) of tumor tissue and α4 integrin of EVs and enhanced vascular permeability, triggering by PDT. Besides, in vivo experiments found that the Catalase-Ce6@MEVs presented M2 macrophage polarization effect.

Conclusion

Catalase-Ce6@MEVs exhibit the cascade targeting ability after laser irradiation and prominent tumor treatment effect in vivo, which may provide new ideas and methods for targeted PDT in clinical practice.

Progress in Nanocarriers Codelivery System to Enhance the Anticancer Effect of Photodynamic Therapy

Photodynamic therapy (PDT) is a promising anticancer noninvasive method and has great potential for clinical applications. Unfortunately, PDT still has many limitations, such as metastatic tumor at unknown sites, inadequate light delivery and a lack of sufficient oxygen. Recent studies have demonstrated that photodynamic therapy in combination with other therapies can enhance anticancer effects. The development of new nanomaterials provides a platform for the codelivery of two or more therapeutic drugs, which is a promising cancer treatment method. The use of multifunctional nanocarriers for the codelivery of two or more drugs can improve physical and chemical properties, increase tumor site aggregation, and enhance the antitumor effect through synergistic actions, which is worthy of further study. This review focuses on the latest research progress on the synergistic enhancement of PDT by simultaneous multidrug administration using codelivery nanocarriers. We introduce the design of codelivery nanocarriers and discuss the mechanism of PDT combined with other antitumor methods. The combination of PDT and chemotherapy, gene therapy, immunotherapy, photothermal therapy, hyperthermia, radiotherapy, sonodynamic therapy and even multidrug therapy are discussed to provide a comprehensive understanding.

Tumour microenvironment-responsive nanoplatform based on biodegradable liposome-coated hollow MnO2 for synergistically enhanced chemotherapy and photodynamic therapy

BACKGROUND

Existing therapeutic efficacy of chemotherapy and photodynamic therapy (PDT) is always affected by some resistance factors from tumour environment (TME), such as hypoxia and the antioxidant defense system.

PURPOSE

This study aims at developing a cascaded intelligent multifunctional nanoplatforms to modulate the TME resistance for synergistically enhanced chemo- and photodynamic therapies.

METHODS

In this study, we synthesised hollow manganese dioxide nanoparticles (HMDNs) loaded with the hydrophilic chemotherapeutic drug (acriflavine, ACF) and the hydrophobic photosensitizer (chlorine6, Ce6), which was further encapsulated by pH-sensitive liposome to form core-shell nanocomposite, with surface modified with arginine-glycine-aspartic acid (RGD) peptide to achieve tumour targeting.

RESULTS

After uptake by tumour cells, the liposome shell was rapidly degraded by the low pH, and the inner core could be released from the liposome. Then, the released HMDNs/ACF/Ce6 would be dissociated by low pH and high levels of intracellular GSH within TME to release encapsulated drugs, thereby resulting in synergistic effects of chemotherapy and PDT. Meanwhile, the released ACF could bind with HIF-1a and then inhibit the expression levels of HIF-1's downstream signalling molecules P-gp and VEGF, which could further strengthen the antitumor effects. As a result, HMDNs/ACF/Ce6@Lipo-RGD NPs with laser irradiation exhibited superior anti-tumour therapeutic efficiency.

Tumor microenvironment-responsive nanozymes achieve photothermal-enhanced multiple catalysis against tumor hypoxia

Reactive oxygen species (ROS)-mediated antitumor modalities that induced oxidative damage of cancer cells have recently acquired increasing attention on account of their noninvasiveness, low systemic toxicity, and high specificity. However, their clinical efficacy was often constrained by complex and various tumor microenvironment (TME), especially hypoxia characteristic and antioxidation effect of glutathione (GSH). Herein, we constructed a multinanozyme system based on hyaluronic acid (HA)-stabilized CuMnO_x nanoparticles (CMOH) loaded with indocyanine green (ICG) with high-efficient ROS generation, O₂ self-evolving function, GSH depletion ability and hyperthermia effect for achieving hypoxic tumor therapy. The CMOH nanozymes exhibited peroxidase-like and oxidase-like activities, which could efficiently catalyze H₂O₂ or O₂ to generate hydroxyl radicals (•OH) or superoxide radicals (•O₂^-) in acidic tumor microenvironment (TME), elevating oxidative stress of tumor. Indocyanine green (ICG) was further loaded into HA-CuMnO_x to form HA-CuMnO_x@ICG nanocomposites (CMOI NCs), which can effectively generate singlet oxygen (¹O₂) and local hyperthermia under light irradiation. The hyperthermia generated by CMOI NCs further enhances the catalytic activities of nanozymes for ROS generation. Meanwhile, the CMOI with catalase-like activity could catalyze H₂O₂ into O₂ for relieving tumor hypoxia and elevate O₂-dependent ROS generation. Notably, CMOI can consume endogenous GSH, thereby impairing tumor antioxidant system and enhancing ROS-based therapy efficacy. After modified with HA, CMOI NCs with tumor targeting ability realized synergistic PTT-enhanced tumor oxidation therapy based on their multimodal properties. Thus, this work contributes to design high-performance therapeutic reagent to overcome the limitation of hypoxia and high antioxidant defense of tumor. STATEMENT OF SIGNIFICANCE: Reactive oxygen species (ROS)-mediated antitumor modalities were often constrained by complex and various tumor microenvironment (TME), especially hypoxia characteristic and antioxidation effect of glutathione (GSH). In this work, a multinanozyme system based on hyaluronic acid (HA)-stabilized CuMnO_x nanoparticles (CMOH) loaded with indocyanine green (ICG) was designed to realize PTT-enhanced multiple catalysis tumor therapy. Although antitumor modalities based on multienzyme catalysis have been developed. Here, we highlighted the responsive catalysis of multienzyme system on tumor microenvironment (TME) and the promoting effect of photothermal effect on ROS production. Both in vitro and in vivo manifested that the enhanced anticancer efficacy of CMOI NCs due to their thermally amplified catalytic activity and TME regulation ability.

Catalase Nanocrystals Loaded with Methylene Blue as Oxygen Self-Supplied, Imaging-Guided Platform for Photodynamic Therapy of Hypoxic Tumors

Photodynamic therapy (PDT) is a well-known method for cancer therapy in the clinic. However, the inherent hypoxia microenvironment of solid tumors enormously restricts the PDT efficiency. Herein, catalase nanocrystals (CatCry) are introduced as in situ oxygen (O₂ )-generating system to relieve tumor hypoxia and enhance PDT efficiency for solid tumors. After loading with photosensitizer methylene blue (MB), a PDT drug platform (CatCry-MB) emerges, allowing for significant increasing PDT efficiency instigated by three factors. First, the high stability and recyclable catalytic activity of CatCry enable a long-term endogenous H₂ O₂ decomposition for continuous O₂ supply for sustained relief of tumor hypoxia. Second, both the produced O₂ and loaded MB are confined within CatCry nanoporous structure, shortening the diffusion distance between O₂ and MB to maximize the production of singlet oxygen (¹ O₂ ). Third, the MB molecules are uniformly dispersed within CatCry lattice, avoiding MB aggregation and causing more MB molecules be activated to produce more ¹ O₂ . With the three complementary mechanisms, tumor hypoxia is eradicated and the resulted enhancement in PDT efficiency is demonstrated in vitro and in vivo. The proposed approach opens up a new venue for the development of other O₂ -dependent tumor treatments, such as chemotherapy, radiotherapy, and immunotherapy.

One-pot synthesis chlorin e6 nano-precipitation for colorectal cancer treatment Ce6 NPs for colorectal cancer treatment

The drug nanoparticles free of additional carriers hold great promise in drug delivery and are suitable for the therapy of cancers. Herein, we developed a one-pot method to prepare chlorin e6 (Ce6) nano-precipitations (Ce6 NPs) for effective photodynamic therapy of colorectal cancer. The drug loading of Ce6 NPs was around 81% and showed acceptable stability, high biocompatibility as well as effective reactive oxygen species (ROS) generation capability. As a result, the Ce6 NPs can produce significantly elevated ROS upon laser irradiations and achieved better anticancer benefits than free Ce6.

Exploring new Horizons in overcoming P-glycoprotein-mediated multidrug-resistant breast cancer via nanoscale drug delivery platforms

The high probability (13%) of women developing breast cancer in their lifetimes in America is exacerbated by the emergence of multidrug resistance after exposure to first-line chemotherapeutic agents. Permeation glycoprotein (P-gp)-mediated drug efflux is widely recognized as the major driver of this resistance. Initial in vitro and in vivo investigations of the co-delivery of chemotherapeutic agents and P-gp inhibitors have yielded satisfactory results; however, these results have not translated to clinical settings. The systemic delivery of multiple agents causes adverse effects and drug-drug interactions, and diminishes patient compliance. Nanocarrier-based site-specific delivery has recently gained substantial attention among researchers for its promise in circumventing the pitfalls associated with conventional therapy. In this review article, we focus on nanocarrier-based co-delivery approaches encompassing a wide range of P-gp inhibitors along with chemotherapeutic agents. We discuss the contributions of active targeting and stimuli responsive systems in imparting site-specific cytotoxicity and reducing both the dose and adverse effects.

Glucose-Targeted Hydroxyapatite/Indocyanine Green Hybrid Nanoparticles for Collaborative Tumor Therapy

Nanoscale hydroxyapatite (nHA) is considered as a promising drug carrier or therapeutic agent against malignant tumors. But the strong agglomeration tendency and lack of active groups seriously hamper their usage in vivo. To address these issues, we fabricated an organic-inorganic hybrid nanosystem composed of poly(acrylic acid) (PAA), nHA, and indocyanine green (ICG), and further modified with glucose to give a targeting nanosystem (GA@HAP/ICG-NPs). These hybrid nanoparticles (∼90 nm) showed excellent storage and physiological stability assisted by PAA and had a sustained drug release in an acidic tumor environment. In vitro cell experiments confirmed that glucose-attached particles significantly promoted cellular uptake and increased intracellular ICG and Ca2+ concentrations by glucose transporter 1 (GLUT1)-mediated endocytosis. Subsequently, the excessive Ca2+ induced cell or organelle damage and ICG triggered photothermal and photodynamic effects (PTT/PDT) under laser irradiation, resulting in enhanced cell toxicity and apoptosis. In vivo tests revealed that the hybrid nanosystem possessed good hemocompatibility and biosafety, facilitating in vivo circulation and usage. NIR imaging further showed that tumor tissues had more drug accumulation, resulting in the highest tumor growth inhibition (87.89%). Overall, the glucose-targeted hybrid nanosystem was an effective platform for collaborative therapy and expected to be further used in clinical trials.

Formulation and Efficacy of Catalase-Loaded Nanoparticles for the Treatment of Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy is the leading cause of permanent brain injury in term newborns and currently has no cure. Catalase, an antioxidant enzyme, is a promising therapeutic due to its ability to scavenge toxic reactive oxygen species and improve tissue oxygen status. However, upon in vivo administration, catalase is subject to a short half-life, rapid proteolytic degradation, immunogenicity, and an inability to penetrate the brain. Polymeric nanoparticles can improve pharmacokinetic properties of therapeutic cargo, although encapsulation of large proteins has been challenging. In this paper, we investigated hydrophobic ion pairing as a technique for increasing the hydrophobicity of catalase and driving its subsequent loading into a poly(lactic-co-glycolic acid)-poly(ethylene glycol) (PLGA-PEG) nanoparticle. We found improved formation of catalase-hydrophobic ion complexes with dextran sulfate (DS) compared to sodium dodecyl sulfate (SDS) or taurocholic acid (TA). Molecular dynamics simulations in a model system demonstrated retention of native protein structure after complexation with DS, but not SDS or TA. Using DS-catalase complexes, we developed catalase-loaded PLGA-PEG nanoparticles and evaluated their efficacy in the Vannucci model of unilateral hypoxic-ischemic brain injury in postnatal day 10 rats. Catalase-loaded nanoparticles retained enzymatic activity for at least 24 h in serum-like conditions, distributed through injured brain tissue, and delivered a significant neuroprotective effect compared to saline and blank nanoparticle controls. These results encourage further investigation of catalase and PLGA-PEG nanoparticle-mediated drug delivery for the treatment of neonatal brain injury.

Synthesis of iridium-based nanocomposite with catalase activity for cancer phototherapy

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) has attracted attention due to its enhanced tumor therapy effect. This study proposes a novel nanoenzyme-based theranostic nanoplatform, IrO₂@MSN@PDA-BSA(Ce6), for the combined PTT and PDT of tumors. IrO₂ was prepared by a simple hydrolysis method and coated with a thin layer of mesoporous silica (MSN) to facilitate the physical adsorption of Chlorin e6 (Ce6). The PDA coating and IrO₂ NPs of the nanoplatform demonstrated an improved photothermal conversion efficiency of 29.8% under NIR irradiation. Further, the Ce6 loading imparts materials with the ability to produce reactive oxygen species (ROS) under 660 nm NIR laser irradiation. It was also proved that the IrO₂ NPs could catalyze the hydrogen peroxide (H₂O₂) in the tumor microenvironment (TME) to generate endogenous oxygen (O₂), thereby enhancing the efficiency of PDT. The in vitro and in vivo experiments indicated that the nanocomposite was highly biocompatible and could produce a satisfactory tumor therapeutic effect. Thus, the findings of the present study demonstrate the viability of using theranostic nanoenzymes for translational medicine.

TMTP1-Modified, Tumor Microenvironment Responsive Nanoparticles Co-Deliver Cisplatin and Paclitaxel Prodrugs for Effective Cervical Cancer Therapy

Background and Purpose

Cisplatin-paclitaxel (TP) combination chemotherapy as the first-line therapy for numerous cancers is hindered by its inadequate accumulation in tumors and severe side effects resulting from non-specific distribution. The aim of this study is to explore whether TMTP1-modified, cisplatin and paclitaxel prodrugs co-loaded nanodrug could improve cervical cancer chemotherapy and relieve its side effects through active and passive tumor targeting accumulation and controlled drug release.

Methods

TDNP, with capacities of active targeting for tumors and controlled drug release, was prepared to co-deliver cisplatin and paclitaxel prodrugs. The characteristics were investigated, including the diameter, surface zeta potential, stability and tumor microenvironment (TME) dependent drug release profiles. Cellular uptake, cytotoxicity, drug accumulation in tumors, antitumor effects and safety analysis were evaluated in vitro and in vivo.

Results

The oxidized cisplatin and the paclitaxel linked to the polymer achieved a high loading effciency of over 80% and TME-dependent sustained drug release. Moreover, TMTP1 modification enhanced cellular uptake of TDNP and further improved the cytotoxicity of TDNP in vitro. In vivo, TDNP showed an extended blood circulation and increased accumulation in SiHa xenograft models with the aid of TMTP1. More importantly, TDNP controlled tumor growth without life-threatening side effects.

Conclusion

Our study provided a novel TP co-delivery platform for targeted chemotherapy of cervical cancer, which was promising to improve the therapeutic effcacy of TP and may also have application in other tumors.

A cyclic nano-reactor achieving enhanced photodynamic tumor therapy by reversing multiple resistances

BACKGROUND

Photodynamic therapy (PDT) is a clinically implemented modality to combat malignant tumor, while its efficacy is largely limited by several resistance factors from tumor microenvironment (TME), such as hypoxia, anti-oxidant systems, and ATP-dependent tumor adaptive resistances. The aim of this work is to construct a multifunctional nanoplatform to remodel multiple resistant TME for enhanced PDT.

RESULTS

Here, a targeting nano-reactor was facilely constructed to reverse the multiple resistances of PDT by incorporating glucose oxidase (GOx) and chlorin e6 (Ce6) into poly (D, L-lactic-co-glycolic acid) (PLGA)/ metal-organic framework (MOF) core-shell nanoassembly, with surface deposition of hyaluronic acid (HA) stabilized MnO2. The nano-reactor could selectively target tumor cells by virtue of surface HA modification, and once internalization, a few reactions were initiated to modulate TME. Glucose was consumed by GOx to inhibit ATP generation, and the produced H2O2 was catalyzed by MnO2 to generate O2 for tumor hypoxia alleviation and photodynamic sensitization, and glutathione (GSH) was also effectively depleted by MnO2 to suppress the tumor antioxidant defense. Consequently, the nano-reactor achieved robust PDT with amplified tumor therapy via intravenous injection.

CONCLUSIONS

This nano-reactor offers a multifunctional nanoplatform to sensitize TME-limited tumor treatment means via reversing multiple resistances.