Post-synthesis strategy to integrate porphyrinic metal–organic frameworks with CuS NPs for synergistic enhanced photo-therapy

In vivo synergistic tumor therapies based on copper sulfide photothermal therapeutic nanoplatforms

Tumor cells may be eliminated by increasing their temperature. This is achieved via photothermal therapy (PTT) by penetrating the tumor tissue with near-infrared light and converting light energy into heat using photothermal agents. Copper sulfide nanoparticles (CuS NPs) are commonly used as PTAs in PTT. In this review, we aimed to discuss the synergism between tumor PTT with CuS NPs and other therapies such as chemotherapy, radiotherapy, dynamic therapies (photodynamic, chemodynamic, and sonodynamic therapy), immunotherapy, gene therapy, gas therapy, and magnetic hyperthermia. Furthermore, we summarized the results obtained with a combination of two treatments and at least two therapies, with PTT as one of the included therapies. Finally, we summarized the benefits and drawbacks of various therapeutic options and state of the art CuS-based PTT and provided future directions for such therapies.

CeO2@CuS@PDA-FA as targeted near-infrared PTT/CDT therapeutic agents for cancer cells

Single tumor treatment method usually has some defects, which makes it difficult to achieve good therapeutic effect. The ingenious combination of multiple tumor treatment methods on a single nanoplatform to achieve multifunctional treatment can effectively improve the efficiency of treatment. The targeted modification of nanomaterials can augment the precision of nanotherapeutic drugs in tumor treatment. Herein, a multifunctional nanoplatform (CeO2@CuS@PDA-FA) based on cerium dioxide nanoparticles engineered with copper sulfide (CeO2@CuS) has been constructed for synergistic photothermal therapy (PTT) and chemodynamic therapy (CDT). The CeO2@CuS were coated using polydopamine (PDA), and the modification of PDA surface by folic acid, in order to achieve the targeted effect for tumors. The localized hyperthermia induced by PTT can further improve the CDT efficiency of the nanoplatform, leading to a PTT/CDT synergistic effect. The nanoplatform possessed the capability of cancer cell-targeted and achieved better therapeutic efficacyin vitro. This work provided a new strategy for combined multifunctional theranostic platform and shows strong potential in practical applications.

An injectable multifunctional hydrogel for eradication of bacterial biofilms and wound healing

Wound treatment is largely influenced by pre-existing hypoxic microenvironments and biofilms, which can severely diminish the efficacy of phototherapy, suggesting the importance of multifunctional nanoplatforms for synergistic treatment of wound infections. Here, we developed a multifunctional injectable hydrogel (PSPG hydrogel) by loading photothermal sensitive sodium nitroprusside (SNP) into Pt-modified porphyrin metal organic framework (PCN) and in situ modification of gold particles to form a near-infrared (NIR) light-triggered all-in-one phototherapeutic nanoplatform. The Pt-modified nanoplatform exhibits a remarkable catalase-like behavior and promotes the continuous decomposition of endogenous H₂O₂ into O₂, thereby enhancing the photodynamic therapy (PDT) effect under hypoxia. Under dual NIR irradiation, PSPG hydrogel can not only produce hyperthermia (η=89.21%) but also generate reactive oxygen species and trigger NO release, contributing jointly to removal of biofilms and disruption of the cell membranes of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). In vivo experiments demonstrated a 99.9% reduction in bacterial burden on wounds. Additionally, PSPG hydrogel can accelerate MRSA-infected and Pseudomonas aeruginosa-infected (P. aeruginosa-infected) wound healing by promoting angiogenesis, collagen deposition, and suppressing inflammatory responses. Furthermore, in vitro and in vivo experiments revealed that PSPG hydrogel has good cytocompatibility. Overall, we proposed an antimicrobial strategy to eliminate bacteria through the synergistic effects of gas-photodynamic-photothermal killing, alleviating hypoxia in the bacterial infection microenvironment, and inhibiting biofilms, offering a new way against antimicrobial resistance and biofilm-associated infections. STATEMENT OF SIGNIFICANCE: The NIR light-triggered multifunctional injectable hydrogel nanoplatform (PSPG hydrogel) based on Pt-decorated gold nanoparticles with sodium nitroprusside (SNP)-loading porphyrin metal organic framework (PCN) as inner templates can efficiently perform photothermal conversion (η=89.21%) to trigger NO release from SNP, while continuously regulating the hypoxic microenvironment at the bacterial infection site through Pt-induced self-oxygenation, achieving efficient sterilization and removal of biofilm by synergistic PDT and PTT phototherapy. In vivo and in vitro experiments demonstrated that the PSPG hydrogel has significant anti-biofilm, antibacterial, and inflammatory regulatory functions. This study proposed an antimicrobial strategy to eliminate bacteria through the synergistic effects of gas-photodynamic-photothermal killing, alleviating hypoxia in the bacterial infection microenvironment, and inhibiting biofilms.

Porous Framework Materials for Bioimaging and Cancer Therapy

Cancer remains one of the most pressing diseases in the world. Traditional treatments, including surgery, chemotherapy, and radiotherapy still show certain limitations. Recently, numerous cancer treatments have been proposed in combination with novel materials, such as photothermal therapy, chemodynamic therapy, immunotherapy, and a combination of therapeutic approaches. These new methods have shown significant advantages in reducing side effects and synergistically enhancing anti-cancer efficacy. In addition to the above approaches, early diagnosis and in situ monitoring of lesion areas are also important for reducing side effects and improving the success rate of cancer therapy. This depends on the decent use of bioimaging technology. In this review, we mainly summarize the recent advances in porous framework materials for bioimaging and cancer therapy. In addition, we present future challenges relating to bioimaging and cancer therapy based on porous framework materials.

CuS Nanoparticles-Loaded and Cisplatin Prodrug Conjugated Fe(III)-MOFs for MRI-Guided Combination of Chemotherapy and NIR-II Photothermal Therapy

Ovarian cancer has become an urgent threat to global female healthcare. Cisplatin, as the traditional chemotherapeutic agent against ovarian cancer, retains several limitations, such as drug resistance and dose-limiting toxicity. In order to solve the above problems and promote the therapeutic effect of chemotherapy, combining chemotherapy and phototherapy has aroused wide interest. In this study, we constructed a versatile cisplatin prodrug-conjugated therapeutic platform based on ultrasmall CuS-modified Fe(III)-metal-organic frameworks (MIL-88) (named M-Pt/PEG-CuS) for tumor-specific enhanced synergistic chemo-/phototherapy. After intravenous injection, M-Pt/PEG-CuS presented obvious accumulation in tumor and Fe(III)-MOFs possessed magnetic resonance imaging (MRI) to guide synergy therapy. Both in vitro and in vivo experimental results showed that M-Pt/PEG-CuS could not only successfully inhibit tumor growth by combining chemotherapy and NIR-II PTT but also avoid the generation of liver damage by the direct treatment of cisplatin(II). Our work presented the development of the nanoplatform as a novel NIR-II photothermal agent, as well as gave a unique combined chemo-photothermal therapy strategy, which might provide new ways of ovarian cancer therapy for clinical translation.

NIR-light-controlled G-quadruplex hydrogel for synergistically enhancing photodynamic therapy via sustained delivery of metformin and catalase-like activity in breast cancer

Severely hypoxic condition of tumour represents a notable obstacle against the efficiency of photodynamic therapy (PDT). While mitochondria targeted therapy by metformin has been considered as a promising strategy for reducing oxygen consumption in tumours, its low treatment sensitivity, short half-life and narrow absorption window in vivo remain the intractable challenges. In this report, 5′-guanosine monophosphate (5′GMP), indocyanine green (ICG), hemin and metformin, were combined to construct a smart G-quadruplex (G4) hydrogel named HMI@GEL for breast cancer (BC) treatment. Benefiting from the photothermal (PTT) effect of ICG, HMI@GEL exhibited excellent characteristics of NIR-light-triggered and persistent drug delivery to maintain high intratumoral concentration of metformin. Furthermore, drug loading concentration of metformin reached an amazing 300 ​mg ​mL⁻¹ in HMI@GEL. To our knowledge, it might be the highest loading efficiency in the reported literatures. With the combination of catalase-mimicking Hemin@mil88, metformin could inhibit tumour mitochondrial respiratory significantly, which sequentially permitted in situ efficient oxygen generation. Remarkable apoptosis and necrosis were achieved by the combination of PTT and synergistically enhanced PDT as well as the activated tumour immunotherapy. Collectively, the HMI@GEL in situ injectable platform showed a promising strategy for enhanced PDT by metformin, and opened new perspectives for treating BC versatilely.

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A NIR-light-controlled G-quadruplex hydrogel HMI@GEL loading metformin was prepared for precision breast cancer therapy.

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The extremely high drug loading capacity (300 ​mg ​mL⁻¹) and persistent delivery of metformin was realized for the first time.

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The combination of catalase-mimicking Hemin@mil88 and metformin dual enhanced intracellular ROS generation.

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The tumour immune microenvironment was dramatically reshaped by synthetic photodynamic/photothermal therapy.

A Fe(III)-porphyrin-oxaliplatin(IV) nanoplatform for enhanced ferroptosis and combined therapy

Since there are several limitations in cancer treatment for traditional chemotherapy, such as side effects, poor prognosis and drug resistance, developing new combined therapy is urgently needed. In this work, a biocompatible, simple and tumor microenvironment-responsive nanotheranostics (PCN-Oxpt/PEG) was built to favor the chemotherapy/ferroptosis/immunomodulation synergism in cancer. This nanotheranostics is constructed by modifying oxaliplatin prodrug and PEG on Fe(III) - porphyrin metal-organic frameworks (PCN(Fe) MOFs). After intravenous injection, the cloak of PEG leads to long circulation, and the Fe(III)-porphyrin MOFs enables dual-model guidance with fluorescence (FL) and magnetic resonance imaging (MRI). Inside the tumor, the intracellular H₂O₂ would be transferred into hydroxyl radicals (•OH) by iron ions released from MOFs, which could trigger the lethal ferroptosis to cancer cells. Meanwhile, oxaliplatin(II) transformed from the loaded oxaliplatin prodrug would result in the chemotherapy, as well as immunogenic cell death (ICD), and the prodrug strategy could also avoid the occurring of liver damage by the direct administration of oxaliplatin(II). It was noticed that the ferroptosis effect was enhanced by triple-assistance during the combined therapy, as followed: (1) glutathione (GSH) would be consumed in the process of oxaliplatin(II) generation from oxaliplatin prodrug; (2) the increased CD8⁺ T cells induced by ICD were able to produce interferon-γ (IFN-γ), which could inhibit the transport of cystine by tumor cells, and impair the activation of glutathione peroxidase 4 (GPX4); (3) the amount of H₂O₂ could be increased by the internalized oxaliplatin and thus further promote the Fenton reaction and ferroptosis. Both in vivo and in vitro results revealed that tumor growing was significantly inhibited by PCN-Oxpt/PEG, taken together, the concomitant of oxaliplatin-mediated chemotherapy and ICD with triple-enhanced ferroptosis offer great prospect in the clinical treatment of cancer.

Biodegradable oxygen-producing manganese-chelated metal organic frameworks for tumor-targeted synergistic chemo/photothermal/ photodynamic therapy

Photodynamic therapy (PDT) is an effective noninvasive therapeutic strategy that can convert oxygen to highly cytotoxic singlet oxygen (¹O₂) through the co-localization of excitation light and photosensitizers. However, compromised by the hypoxic tumor microenvironment, the therapeutic efficacy of PDT is reduced seriously. Herein, to overcome tumor-associated hypoxia, and further achieve tumor-targeted synergistic chemotherapy/PDT/photothermal therapy (PTT), we have constructed a biodegradable oxygen-producing nanoplatform (named Ini@PM-HP), which was composed of the porous metal-organic framework (PCN-224(Mn)), the poly (ADP-ribose) polymerase (PARP) inhibitor (Iniparib), and the polydopamine-modified hyaluronic acid (HA-PDA). Since HA can specifically bind to the overexpressed HA receptors (cluster determinant 44, CD44) on tumor cell, Ini@PM-HP prefers to accumulate at the tumor site once injected intravenously. Then iniparib can be released in tumor environment (TME), thereby dysfunctioning DNA damage repair and promoting cell apoptosis. At the same time, the chelating of Mn and tetrakis(4-carboxyphenyl) porphyrin (Mn-TCPP) can generate O₂ in situ by reacting with endogenous H₂O₂, relieving the hypoxic TME and achieving enhanced PDT. Moreover, owing to the high photothermal conversion efficiency of PDA, PTT can be driven by the 808 nm laser irradiation. As systematically demonstrated in vitro and in vivo, this nanotherapeutic approach enables the combined therapy with great inhibition on tumor. Overall, the as-prepared nanoplatform provide a promising strategy to overcome tumor-associated hypoxia, and shows great potential for combination tumor therapy. STATEMENT OF SIGNIFICANCE: A delicately designed biodegradable oxygen-producing nanoplatform Ini@PM-HP is constructed to achieve combination therapy of solid tumors. Taking advantage of the active-targeting, PTT, enhanced PDT and PARPi, this nanotherapeutic approach successfully enables the combined chemo/photothermal/photodynamic therapy with great inhibition of solid tumors.

Metal-Organic Frameworks for Bioimaging: Strategies and Challenges

Metal-organic frameworks (MOFs), composited with metal ions and organic linkers, have become promising candidates in the biomedical field own to their unique properties, such as high surface area, pore-volume, tunable pore size, and versatile functionalities. In this review, we introduce and summarize the synthesis and characterization methods of MOFs, and their bioimaging applications, including optical bioimaging, magnetic resonance imaging (MRI), computed tomography (CT), and multi-mode. Furthermore, their bioimaging strategies, remaining challenges and future directions are discussed and proposed. This review provides valuable references for the designing of molecular bioimaging probes based on MOFs.

Current status and future prospects of nanoscale metal–organic frameworks in bioimaging

The importance of diagnosis and in situ monitoring of lesion regions and transportation of bioactive molecules has a pivotal effect on successful treatment, reducing side effects, and increasing the chances of survival in the case of diseases.

Photosensitizer-based metal-organic frameworks for highly effective photodynamic therapy

Photodynamic therapy (PDT) uses a photosensitizer, molecular oxygen, and visible light as an alternative clinical protocol against located malignant tumors and other diseases. More recently, PDT has been combined to immunotherapy as a promising option to treat metastatic cancer. However, previous generations of photosensitizers (PSs) revealed clinical difficulties such as long-term skin photosensitivity (first generation), the need for drug delivery vehicles (second generation), and intracellular self-aggregation (third generation), which have generated a somewhat confusing scenario in PDT approaches and evolution. Recently, metal-organic frameworks (MOFs) with exceptionally high PS loading as a building unit of MOF framework have emerged as fourth-generation PS and presented outstanding outcomes under pre-clinical studies. For PS-based MOFs, the inorganic building unit (metal ions/clusters) plays an important role as a coadjuvant in PDT to alleviate hypoxia, to decrease antioxidant species, to yield ROS, or to act as a contrast agent for imaging-guided therapy. In this review, we intend to carry out a broad update on the recent history and the characteristics of PS-based MOFs from basic chemistry to the structure relationship with biological application in PDT. The details and variables that result in different photophysics, size, and morphology, are discussed. Also, we present an overview of the achievements on the pre-clinical assays in combination with other strategies, including alleviating hypoxia in solid tumors, chemotherapy, and the most recent immunotherapy for cancer.

Biodegradable Metal Organic Frameworks for Multimodal Imaging and Targeting Theranostics

Though there already had been notable progress in developing efficient therapeutic strategies for cancers, there still exist many requirements for significant improvement of the safety and efficiency of targeting cancer treatment. Thus, the rational design of a fully biodegradable and synergistic bioimaging and therapy system is of great significance. Metal organic framework (MOF) is an emerging class of coordination materials formed from metal ion/ion clusters nodes and organic ligand linkers. It arouses increasing interest in various areas in recent years. The unique features of adjustable composition, porous and directional structure, high specific surface areas, biocompatibility, and biodegradability make it possible for MOFs to be utilized as nano-drugs or/and nanocarriers for multimodal imaging and therapy. This review outlines recent advances in developing MOFs for multimodal treatment of cancer and discusses the prospects and challenges ahead.

A versatile and low-toxicity material for photothermal therapy in deeper tissues

The limited depth of the near infrared (NIR) response is one of the major flaws of the present photothermal therapy (PTT). In this article, thermosensitive polyurethane urea (TPUU) was synthesized by polymerization. Subsequent experiments showed that, compared with classical photosensitizers, TPUU has higher photothermal effects and lower cytotoxicity. These valuable properties could make the present PTT research provide more therapeutic options among different tissues and organs. As a practical example, TPUU was applied to regulate the intestinal flora through external NIR irradiation, which implied its promising expanded applications in deeper tissues.

The recent progress on metal-organic frameworks for phototherapy

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

Modified nanoscale metal organic framework-based nanoplatforms in photodynamic therapy and further applications

Photodynamic therapy (PDT) has emerged as a modality in cancer treatment because it is less invasive and highly selective compared with conventional chemotherapy and radiation therapy. Nanoscale metal organic frameworks (nMOFs) have exhibited great potential for use in constructing nanoplatforms for improved PDT because of their unique structural advantages such as large surface areas, high porosities, tunable compositions and various other modifications. The large majority of current nMOF-based systems employ specific modifying groups to overcome the deficiencies previously observed when using older nMOFs in PDT. In this review, we summarize modifications to these systems such as enhancing singlet oxygen generation by introducing photoactive agents, alleviating tumor hypoxia and engineering active targeting abilities. The applications of MOF-based nanoparticles in synergistic cancer therapies that include PDT, as well as in theranostics are also discussed. Finally, we discuss some of the challenges faced in this field and the future prospects for the use of nMOFs in PDT.

A multifunctional SN38-conjugated nanosystem for defeating myelosuppression and diarrhea induced by irinotecan in esophageal cancer

A combination of chemotherapy and phototherapy has been proposed as a promising treatment for esophageal cancer (EC). Irinotecan as a first-line treatment option is widely prescribed for metastatic EC, however, its clinical application is extremely restricted by the low conversion rate to SN38, severe myelosuppression and diarrhea. As a more potent active metabolite of irinotecan, SN38 is a better substitution for irinotecan, but the poor water solubility and the difficulty of encapsulation hindered its medical application. Herein, a multifunctional SN38-conjugated nanosystem (FA-PDA@PZM/SN38@BSA-MnO2, denoted as FA-PPSM) is designed for overcoming the above-mentioned drawbacks and achieving collaborative chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT). The tumor acidic microenvironment induces decomposition of BSA-MnO2 nanoparticles into O2 and Mn2+, thus enhancing oxygen-dependent PDT efficacy; meanwhile, Mn2+ can be employed as a magnetic resonance imaging (MRI) contrast agent. Under 650 and 808 nm laser irradiation, the FA-PPSM nanocomposites exhibit superior antitumor efficacy in Eca-109-tumor bearing mice. Notably, there is low gastrointestinal toxicity and myelosuppression in the FA-PPSM treated mice compared with those treated with irinotecan (alone). Taken together, this work highlights the great potential of the FA-PPSM nanocomposites for MRI-guided chemotherapy in combination with endoscopic light therapy for esophageal cancer.

NIR II-Excited and pH-Responsive Ultrasmall Nanoplatform for Deep Optical Tissue and Drug Delivery Penetration and Effective Cancer Chemophototherapy

The limited tumor tissue penetration of many nanoparticles remains a formidable challenge to their therapeutic efficacy. Although several photonanomedicines have been applied to improve tumor penetration, the first near-infrared window mediated by the low optical tissue penetration depth severely limits their anticancer effectiveness. To achieve deep optical tissue and drug delivery penetration, a near-infrared second window (NIR-II)-excited and pH-responsive ultrasmall drug delivery nanoplatform was fabricated based on BSA-stabilized CuS nanoparticles (BSA@CuS NPs). The BSA@CuS NPs effectively encapsulated doxorubicin (DOX) via strong electrostatic interactions to form multifunctional nanoparticles (BSA@CuS@DOX NPs). The BSA@CuS@DOX NPs had an ultrasmall size, which allowed them to achieve deeper tumor penetration. They also displayed stronger NIR II absorbance-mediated deep optical tissue penetration than that of the NIR I window. Moreover, the multifunctional nanoplatform preferentially accumulated in tumor sites, induced tumor hyperthermia, and generated remarkably high ROS levels in tumor sites upon NIR-II laser (1064 nm) irradiation. More importantly, our strategy achieved excellent synergistic effects of chemotherapy and phototherapy (chemophototherapy) under the guidance of photothermal imaging. The developed nanoparticles also showed good biocompatibility and bioclearance properties. Therefore, our work demonstrated a facile strategy for fabricating a multifunctional nanoplatform that is a promising candidate for deep tumor penetration as an effective antitumor therapy.

Metal–organic frameworks: a future toolbox for biomedicine?

The present review focuses on the use of Metal–Organic Frameworks, (MOFs) highlighting the most recent developments in the biological field and as bio-sensors.