Cancer Cell-Targeted Photosensitizer and Therapeutic Protein Co-Delivery Nanoplatform Based on a Metal-Organic Framework for Enhanced Synergistic Photodynamic and Protein Therapy

Evodiamine encapsulated by hyaluronic acid modified zeolitic imidazolate framework-8 for tumor targeted therapy

Evodiamine (EVO), a natural bioactive compound extracted from Evodia rutaecarpa, shows therapeutic ability against malignant melanoma. However, the poor solubility and bioavailability of EVO limit its clinical application. Metal-organic frameworks (MOFs) have shown excellent physical and chemical properties and are widely used as drug delivery systems. Among them, zeolitic imidazolate framework-8 (ZIF-8) is a research popular material because of its unique properties, such as hydrothermal stability, non-toxicity, biocompatibility, and pH sensitivity. In this study, in order to load EVO, a drug carrier that hyaluronic acid (HA) modified zeolitic imidazolate framework-8 (ZIF-8) is synthesized. This drug carrier has shown drug loading with 6.2 ± 0.6%, and the nano drugs (EVO@ZIF-8/HA) have good dispersibility. Owing to the decoration HA of EVO@ZIF-8, the potential of the nano drugs is reversed from the positive charge to the negative charge, which is beneficial to blood circulation in vivo. Furthermore, because the CD44-expressing in tumor cells is excessed, the endocytosis and accumulation of nano drugs in tumor cells are beneficial to improvement. Compared with free EVO, EVO@ZIF-8/HA has shown a significantly improved anti-tumor efficacy in vitro and in vivo. In summary, the drug carrier effectively addresses the challenges that are caused by the strong hydrophobicity and low bioavailability of EVO, thereby targeted tumor therapy of EVO can be achieved.

Juxtaposing the antibacterial activities of different ZIFs in photodynamic therapy and their oxidative stress approach

Instigating oxidative stress is a crucial aspect of antibacterial therapy. Yet, its behavior is poorly understood in the context of zeolitic imidazolate frameworks (ZIFs) - a group of highly promising antibacterial agents. To address this gap, a series of ZIF@Ce6 particles were synthesized to investigate the impact of particle shape, size, and metal ion type on oxidative stress and bactericidal activity. For the first time, the interplay between the physicochemical properties and antibacterial activities of different ZIF@Ce6 particles is demonstrated, while unearthing their oxidative stress strategy in photodynamic therapy. Notably, the incorporation of chlorin e6 (Ce6), combined with light irradiation, amplified the bactericidal effect of the ZIFs and achieved a rare minimum inhibition concentration (MIC) of 12.5 µgmL-1 for ZIF-8. We discovered that singlet oxygen (1O2) production varies with particle shape and size, while photodynamic activity reshuffles the antibacterial performance sequence from pristine to modified ZIF-8. Interestingly, reactive oxygen species (ROS) accumulation and glutathione depletion tests revealed that oxidative stress in pristine ZIF-8 is predominantly induced by ROS, whereas both ROS and glutathione contribute to the oxidative stress in ZIF@Ce6 and pristine ZIF-67. When bacteria are preincubated with the antioxidant N-acetyl cysteine, the bactericidal activity of ZIF@Ce6 increases while the activity of pristine ZIF-8 is reduced and that of ZIF-67 remains unchanged. This study deepens our understanding of the antibacterial properties of ZIFs and their oxidative stress paths, paving way for the fabrication of ZIF-based materials with enriched and targeted antibacterial properties.

Nano- and Micro-Platforms in Therapeutic Proteins Delivery for Cancer Therapy: Materials and Strategies

Proteins have emerged as promising therapeutics in oncology due to their great specificity. Many treatment strategies are developed based on protein biologics, such as immunotherapy, starvation therapy, and pro-apoptosis therapy, while some protein biologics have entered the clinics. However, clinical translation is severely impeded by instability, short circulation time, poor transmembrane transportation, and immunogenicity. Micro- and nano-particles-based drug delivery platforms are designed to solve those problems and enhance protein therapeutic efficacy. This review first summarizes the different types of therapeutic proteins in clinical and research stages, highlighting their administration limitations. Next, various types of micro- and nano-particles are described to demonstrate how they can overcome those limitations. The potential of micro- and nano-particles are then explored to enhance the therapeutic efficacy of proteins by combinational therapies. Finally, the challenges and future directions of protein biologics carriers are discussed for optimized protein delivery.

Fe-HCOF-PEG2000 as a Hypoxia-Tolerant Photosensitizer to Trigger Ferroptosis and Enhance ROS-Based Cancer Therapy

Background

The hypoxic tumor microenvironment and single mechanisms severely limit the photodynamic therapy (PDT) efficiency of covalent organic framework (COF) nanoparticles in cancer treatment.

Purpose

Here, we propose an iron-loaded, hydrophilic 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG2000)-modified hollow covalent organic framework (HCOF), Fe-HCOF-PEG2000, for use in hypoxic PDT and ferroptosis therapy owing to its type I and II photodynamic ability and iron nanoparticle loading property.

Results

Fe-HCOF-PEG2000 nanoparticles (Fe-HCOFs-PEG2000) with semiconducting polymers and microporous skeletons allow efficient photophysical properties. Moreover, the iron nanoparticles on Fe-HCOF-PEG2000 caused ferroptosis and further enhanced tumor elimination under normoxic and hypoxic conditions. DSPE-PEG2000 endowed Fe-HCOF-PEG2000 with hydrophilicity, allowing it to circulate and accumulate in organs rich in blood supply, especially tumors. 808 nm NIR activated Fe-HCOF-PEG2000 aggregated in tumors and significantly inhibited tumor growth under hypoxia.

Conclusion

To our knowledge, Fe-HCOF-PEG2000 is the leading combination of type I/II PDT and ferroptosis. The strong antitumor effects of this nanomaterial suggest prospects for clinical translation as a tumor nanotherapy drug.

Fabrication of pH-responsive temozolomide (TMZ)-clacked tannic acid-altered zeolite imidazole nanoframeworks (ZIF-8) enhance anticancer activity and apoptosis induction in glioma cancer cells

Glioma cancer is the primary cause of cancer-related fatalities globally for both men and women. Traditional chemotherapy treatments for this condition frequently result in reduced efficacy and significant adverse effects. This investigation developed a new drug delivery system for the chemotherapeutic drug temozolomide (TMZ) using pH-sensitive drug delivery zeolitic imidazolate frameworks (ZIF-8). These nanoplatforms demonstrate excellent biocompatibility and hold potential for cancer therapy. Utilizing the favorable reaction milieu offered by ZIFs, a 'one-pot method' was employed for the fabrication and loading of drugs, leading to a good capacity for loading. TMZ@TA@ZIF-8 NPs exhibit a notable response to an acidic milieu, resulting in an enhanced drug release pattern characterized by a controlled release outcome. The effectiveness of TMZ@TA@ZIF-8 NPs in inhibiting the migration and invasion of U251 glioma cancer cells, as well as promoting apoptosis, was confirmed through various tests, including MTT (3-(4,5)-dimethylthiahiazo(-z-y1)) assay, DAPI/PI dual staining, and cell scratch assay. The biochemical fluorescent staining assays showed that TMZ@TA@ZIF-8 NPs potentially improved ROS, reduced MMP, and triggered apoptosis in U251 cells. In U251 cells treated with NPs, the p53, Bax, Cyt-C, caspase-3, -8, and -9 expressions were significantly enhanced, while Bcl-2 expression was diminished. These outcomes show the potential of TMZ@TA@ZIF-8 NPs as a therapeutic agent with anti-glioma properties. Overall, the pH-responsive drug delivery systems we fabricated using TMZ@TA@ZIF-8 NPs show great potential for cancer treatment. This approach has the potential to make significant contributions to the improvement of cancer therapy by overcoming the problems associated with TMZ-based treatments.

Photoresponsive metal-organic framework materials for advance applications

The interaction between light and materials produces a range of phenomena within molecular systems, leading to advanced applications in the field of materials science. In this regard, metal-organic framework (MOF) materials have become superior candidates to others because of their easy tailor-made synthetic methods via incorporation of photoactive moieties into their structural assembly. Photoresponsive MOFs exhibit a massive variety of exciting properties, including photochromism, photomagnetism, photoluminescence, photon up or down conversion, photoconductivity, nonlinear optical properties, photosalient effects and photoinduced switching of conformations. These photoresponsive properties of MOFs regulate different potential applications, such as on-demand gas sorption and separation, optical sensing, fabrication of photoactuators and photosensing electronic devices, dye degradation, catalysis, cargo delivery, ink-free erasable printing, bio-imaging and drug delivery in biological systems. Therefore, judicious crystal engineering along with an understanding of their structure-property relationship will lead to the fabrication of desired photosensitive MOFs. Herein, we attempted to incorporate categorical descriptions based on advanced applications of photoresponsive MOFs considering a wide range of recent publications.

Better together: nanoscale co-delivery systems of therapeutic agents for high-performance cancer therapy

Combination therapies can enhance the sensitivity of cancer to drugs, lower drug doses, and reduce side effects in cancer treatment. However, differences in the physicochemical properties and pharmacokinetics of different therapeutic agents limit their application. To avoid the above dilemma and achieve accurate control of the synergetic ratio, a nanoscale co-delivery system (NCDS) has emerged as a prospective tool for combined therapy in cancer treatment, which is increasingly being used to co-load different therapeutic agents. In this study, we have summarized the mechanisms of therapeutic agents in combination for cancer therapy, nanoscale carriers for co-delivery, drug-loading strategies, and controlled/targeted co-delivery systems, aiming to give a general picture of these powerful approaches for future NCDS research studies.

Charge Conversional Biomimetic Nanosystem for Synergistic Photodynamic/Protein Therapy

Cytochrome C (Cytc) has received considerable attention due to its ability to induce tumor apoptosis and generate oxygen to improve photodynamic therapy (PDT) efficiency. However, the damage to normal tissues caused by nonspecific accumulation of Cytc limits its application. Herein, in order to reduce its toxicity to normal tissues while retaining its activity, a charge conversional biomimetic nanosystem (CA/Ce6@MSN-4T1) is proposed to improve the tumor targeting ability and realize controlled release of Cytc in the tumor microenvironment. This nanosystem is constructed by coating tumor cell membrane on mesoporous silica nanoparticles coloaded with a photosensitizer (chlorin e6, Ce6) and the citraconic anhydride conjugated Cytc (CA) for synergistic photodynamic/protein therapy. The coating of the tumor cell membrane endows the nanoparticles with homologous targeting ability to the same cancer cells as well as immune escaping capability. CA undergoes charge conversion in the acidic environment of the tumor to achieve a controlled release of Cytc. The released Cytc can relieve cellular hypoxia to improve the PDT efficiency of Ce6 and can induce programmed cell death. Both in vitro and in vivo studies demonstrated that CA/Ce6@MSN-4T1 can efficiently inhibit the growth of tumors through synergistic photodynamic/protein therapy, and meanwhile show reduced side effects on normal tissues.

Multifunctional fucoidan-loaded Zn-MOF-encapsulated microneedles for MRSA-infected wound healing

Infected wound healing remains a challenging task in clinical practice due to several factors: (I) drug-resistant infections caused by various pathogens, (II) persistent inflammation that hinders tissue regeneration and (III) the ability of pathogens to persist intracellularly and evade antibiotic treatment. Microneedle patches (MNs), recognized for their effecacious and painless subcutaneous drug delivery, could greatly enhance wound healing if integrated with antibacterial functionality and tissue regenerative potential. A multifunctional agent with subcellular targeting capability and contained novel antibacterial components, upon loading onto MNs, could yield excellent therapeutic effects on wound infections. In this study, we sythesised a zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) loaded with low molecular weight fucoidan (Fu) and further coating by hyaluronic acid (HA), obtained a multifunctional HAZ@Fu NPs, which could hinders Methicillin-resistant Staphylococcus aureus (MRSA) growth and promotes M2 polarization in macrophages. We mixed HAZ@Fu NPs with photocrosslinked gelatin methacryloyl (GelMA) and loaded it into the tips of the MNs (HAZ@Fu MNs), administered to mice model with MRSA-infected full-thickness cutaneous wounds. MNs are able to penetrate the skin barrier, delivering HAZ@Fu NPs into the dermal layer. Since cells within infected tissues extensively express the HA receptor CD44, we also confirmed the HA endows the nanoparticles with the ability to target MRSA in subcellular level. In vitro and in vivo murine studies have demonstrated that MNs are capable of delivering HAZ@Fu NPs deep into the dermal layers. And facilitated by the HA coating, HAZ@Fu NPs could target MRSA surviving at the subcellular level. The effective components, such as zinc ions, Fu, and hyaluronic acid could sustainably released, which contributes to antibacterial activity, mitigates inflammation, promotes epithelial regeneration and fosters neovascularization. Through the RNA sequencing of macrophages post co-culture with HAZ@Fu, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis reveals that the biological functionalities associated with wound healing could potentially be facilitated through the PI3K-Akt pathway. The results indicate that the synergistic application of HAZ@Fu NPs with biodegradable MNs may serve as a significant adjunct in the treatment of infected wounds. The intricate mechanisms driving its biological effects merit further investigation.

Tunable Zeolitic Imidazolate Framework-8 Nanoparticles for Biomedical Applications

Zeolite imidazole framework-8 (ZIF-8) is the most prestigious one among zeolitic imidazolate framework (ZIF) with tunable dimensions and unique morphological features. Utilizing its synthetic adjustability and structural regularity, ZIF-8 exhibits enhanced flexibility, allowing for a wide range of functionalities, such as loading of nanoparticle components while preserving biomolecules activity. Extensive efforts are made from investigating synthesis techniques to develop novel applications over decades. In this review, the development and recent progress of various synthesis approaches are briefly summarized. In addition, its interesting properties such as adjustable porosity, excellent thermal, and chemical stabilities are introduced. Further, five representative biomedical applications are highlighted based on above physicochemical properties. Finally, the remaining challenges and offered insights into the future outlook are also discussed. This review aims to understand the co-relationships between structures and biomedical functionalities, offering the opportunity to construct attractive materials with promising characteristics.

Biomedical application of metal-organic frameworks (MOFs) in cancer therapy: Stimuli-responsive and biomimetic nanocomposites in targeted delivery, phototherapy and diagnosis

The nanotechnology is an interdisciplinary field that has become a hot topic in cancer therapy. Metal-organic frameworks (MOFs) are porous materials and hybrid composites consisted of organic linkers and metal cations. Despite the wide application of MOFs in other fields, the potential of MOFs for purpose of cancer therapy has been revealed by the recent studies. High surface area and porosity, significant drug loading and encapsulation efficiency are among the benefits of using MOFs in drug delivery. MOFs can deliver genes/drugs with selective targeting of tumor cells that can be achieved through functionalization with ligands. The photosensitizers and photo-responsive nanostructures including carbon dots and gold nanoparticles can be loaded in/on MOFs to cause phototherapy-mediated tumor ablation. The immunogenic cell death induction and increased infiltration of cytotoxic CD8+ and CD4+ T cells can be accelerated by MOF platforms in providing immunotherapy of tumor cells. The stimuli-responsive MOF platforms responsive to pH, redox, enzyme and ion can accelerate release of therapeutics in tumor site. Moreover, MOF nanocomposites can be modified ligands and green polymers to improve their selectivity and biocompatibility for cancer therapy. The application of MOFs for the detection of cancer-related biomarkers can participate in the early diagnosis of patients.

Enhanced photodynamic therapy through multienzyme-like MOF for cancer treatment

Overcoming resistance to apoptosis is a major challenge in cancer therapy. Recent research has shown that manipulating mitochondria, the organelles critical for energy metabolism in tumor cells, can increase the effectiveness of photodynamic therapy and trigger apoptosis in tumor cells. However, there is currently insufficient research and effective methods to exploit mitochondrial damage to induce apoptosis in tumor cells and improve the effectiveness of photodynamic therapy. In this study, we present a novel nanomedicine delivery and therapeutic system called PyroFPSH, which utilizes a nanozymes-modified metal-organic framework as a carrier. PyroFPSH exhibits remarkable multienzyme-like activities, including glutathione peroxidase (GPx) and catalase (CAT) mimicry, allowing it to overcome apoptosis resistance, reduce endogenous glutathione levels, and continuously generate reactive oxygen species (ROS). In addition, PyroFPSH can serve as a carrier for the targeted delivery of sulfasalazine, a drug that can induce mitochondrial depolarization in tumor cells, thereby reducing oxygen consumption and energy supply in the mitochondria of tumor cells and weakening resistance to other synergistic treatment approaches. Our experimental results highlight the potential of PyroFPSH as a versatile nanoplatform in cancer treatment. This study expands the biomedical applications of nanomaterials as platforms and enables the integration of various novel therapeutic strategies to synergistically improve tumor therapy. It deepens our understanding of multienzyme-mimicking active nanocarriers and mitochondrial damage through photodynamic therapy. Future research can further explore the potential of PyroFPSH in clinical cancer treatment and improve its drug loading capacity, biocompatibility and targeting specificity. In summary, PyroFPSH represents a promising therapeutic approach that can provide new insights and possibilities for cancer treatment.

Oxygen-carrying acid-responsive Cu/ZIF-8 for photodynamic antibacterial therapy against cariogenic Streptococcus mutans infection

Caries as a result of acid demineralization is the most common oral microbial infectious disease. Due to the small and complex intraoral operating space, it is challenging to completely remove Streptococcus mutans (S. mutans) and other cariogenic bacteria. As an intelligent acid-responsive photosensitive nanomaterial, O2-Cu/ZIF-8@Ce6/ZIF-8@HA (OCZCH) was chosen to adapt to the anaerobic and acidic microenvironment for inactivating S. mutans. In this work, OCZCH not only exhibits a regular nanomorphology in SEM and TEM images but also shows intelligent acid responsiveness as evidenced by the release of Ce6 and oxygen. When excited by near-infrared light at 650 nm, Ce6 releases reactive oxygen species (ROS) that act synergistically with internal oxygen to significantly enhance the antimicrobial therapeutic effect of photodynamic therapy (PDT). In vitro antimicrobial experiments showed that OCZCH could achieve an impressive sterilization effect against S. mutans and biofilm. Notably, the acid-producing ability of the bacteria was also significantly inhibited. With its oxygen-carrying photosensitizing properties, excellent responsiveness to acidic environments, and antimicrobial capacity under anaerobic conditions, OCZCH is considered an innovative candidate for clinical application in treating dental caries.

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.

Biomimetic and bioorthogonal nanozymes for biomedical applications

Nanozymes mimic the function of enzymes, which drive essential intracellular chemical reactions that govern biological processes. They efficiently generate or degrade specific biomolecules that can initiate or inhibit biological processes, regulating cellular behaviors. Two approaches for utilizing nanozymes in intracellular chemistry have been reported. Biomimetic catalysis replicates the identical reactions of natural enzymes, and bioorthogonal catalysis enables chemistries inaccessible in cells. Various nanozymes based on nanomaterials and catalytic metals are employed to attain intended specific catalysis in cells either to mimic the enzymatic mechanism and kinetics or expand inaccessible chemistries. Each nanozyme approach has its own intrinsic advantages and limitations, making them complementary for diverse and specific applications. This review summarizes the strategies for intracellular catalysis and applications of biomimetic and bioorthogonal nanozymes, including a discussion of their limitations and future research directions.

Design and fabrication of intracellular therapeutic cargo delivery systems based on nanomaterials: current status and future perspectives

Intracellular cargo delivery, the introduction of small molecules, proteins, and nucleic acids into a specific targeted site in a biological system, is an important strategy for deciphering cell function, directing cell fate, and reprogramming cell behavior. With the advancement of nanotechnology, many researchers use nanoparticles (NPs) to break through biological barriers to achieving efficient targeted delivery in biological systems, bringing a new way to realize efficient targeted drug delivery in biological systems. With a similar size to many biomolecules, NPs possess excellent physical and chemical properties and a certain targeting ability after functional modification on the surface of NPs. Currently, intracellular cargo delivery based on NPs has emerged as an important strategy for genome editing regimens and cell therapy. Although researchers can successfully deliver NPs into biological systems, many of them are delivered very inefficiently and are not specifically targeted. Hence, the development of efficient, target-capable, and safe nanoscale drug delivery systems to deliver therapeutic substances to cells or organs is a major challenge today. In this review, on the basis of describing the research overview and classification of NPs, we focused on the current research status of intracellular cargo delivery based on NPs in biological systems, and discuss the current problems and challenges in the delivery process of NPs in biological systems.

Genetically engineered nanovesicles mobilize synergistic antitumor immunity by ADAR1 silence and PDL1 blockade

Growing evidence has proved that RNA editing enzyme ADAR1, responsible for detecting endogenous RNA species, was significantly associated with poor response or resistance to immune checkpoint blockade (ICB) therapy. Here, a genetically engineered nanovesicle (siAdar1-LNP@mPD1) was developed as an RNA interference nano-tool to overcome tumor resistance to ICB therapies. Small interfering RNA against ADAR1 (siAdar1) was packaged into a lipid nanoparticle (LNP), which was further coated with plasma membrane extracted from the genetically engineered cells overexpressing PD1. siAdar1-LNP@mPD1 could block the PD1/PDL1 immune inhibitory axis by presenting the PD1 protein on the coating membranes. Furthermore, siAdar1 could be effectively delivered into cancer cells by the designed nanovesicle to silence ADAR1 expression, resulting in an increased type I/II interferon (IFN-β/γ) production and making the cancer cells more sensitive to secreted effector cytokines such as IFN-γ with significant cell growth arrest. These integrated functions confer siAdar1-LNP@mPD1 with robust and comprehensive antitumor immunity, as evidenced by significant tumor growth regression, abscopal tumor prevention, and effective suppression of lung metastasis, through a global remodeling of the tumor immune microenvironment. Overall, we provided a promising translatable strategy to simultaneously silence ADAR1 and block PDL1 immune checkpoint to boost robust antitumor immunity.

Modulating tumor mechanics with nanomedicine for cancer therapy

Over the past several decades, the importance of the tumor mechanical microenvironment (TMME) in cancer progression or cancer therapy has been recognized by researchers worldwide. The abnormal mechanical properties of tumor tissues include high mechanical stiffness, high solid stress, and high interstitial fluid pressure (IFP), which form physical barriers resulting in suboptimal treatment efficacy and resistance to different types of therapy by preventing drugs infiltrating the tumor parenchyma. Therefore, preventing or reversing the establishment of the abnormal TMME is critical for cancer therapy. Nanomedicines can enhance drug delivery by exploiting the enhanced permeability and retention (EPR) effect, so nanomedicines that target and modulate the TMME can further boost antitumor efficacy. Herein, we mainly discuss the nanomedicines that can regulate mechanical stiffness, solid stress, and IFP, with a focus on how nanomedicines change abnormal mechanical properties and facilitate drug delivery. We first introduce the formation, characterizing methods and biological effects of tumor mechanical properties. Conventional TMME modulation strategies will be briefly summarized. Then, we highlight representative nanomedicines capable of modulating the TMME for augmented cancer therapy. Finally, current challenges and future opportunities for regulating the TMME with nanomedicines will be provided.

Zeolitic Imidazolate Framework-8 (ZIF-8) as a Drug Delivery Vehicle for the Transport and Release of Telomerase Inhibitor BIBR 1532

Telomerase is constitutively overexpressed in the majority of human cancers and telomerase inhibition provides a promising broad-spectrum anticancer therapeutic strategy. BIBR 1532 is a well-known synthetic telomerase inhibitor that blocks the enzymatic activity of hTERT, the catalytic subunit of telomerase. However, water insolubility of BIBR 1532 leads to low cellular uptake and inadequate delivery and thus, limits its anti-tumor effects. Zeolitic imidazolate framework-8 (ZIF-8) is considered as an attractive drug delivery vehicle for improved transport, release and anti-tumor effects of BIBR 1532. Herein, ZIF-8 and BIBR 1532@ZIF-8 were synthesized, respectively, and the physicochemical characterizations confirmed the successful encapsulation of BIBR 1532 in ZIF-8 coupled with an improved stability of BIBR 1532. ZIF-8 could alter the permeability of lysosomal membrane probably by the imidazole ring-dependent protonation. Moreover, ZIF-8 encapsulation facilitated the cellular uptake and release of BIBR 1532 with more accumulation in the nucleus. BIBR 1532 encapsulation with ZIF-8 triggered a more obvious growth inhibition of cancer cells as compared with free BIBR 1532. A more potent inhibition on hTERT mRNA expression, aggravated G0/G1 arrest accompanied with an increased cellular senescence were detected in BIBR 1532@ZIF-8-treated cancer cells. Our work has provided preliminary information on improving the transport, release and efficacy of water-insoluble small molecule drugs by using ZIF-8 as a delivery vehicle.

Ultrasensitive visual detection of the food-borne pathogen via MOF encapsulated enzyme

Various methods have been made to achieve sensitive detection (10 CFU/mL) of Escherichia coli O157:H7 (E. coli) in real samples, however, they are complex, time-consuming, or instrument-dependent. Enzyme-catalyzed reactions are one of the most efficient methods to amplify signals for sensitive detection. ZIF-8 owning stability, porosity, and high specific area are suitable for embedding enzymes which can effectively protect enzyme activity and thus improve detection sensitivity. Herein, a simple visual assay of E. coli with the limits of detection of 1 CFU/mL was developed based on this stable enzyme-catalyzed amplified system. A microbial safety test of milk, orange juice, seawater, cosmetic, and hydrolyzed yeast protein, was successfully performed with the limits of detection of 10 CFU/mL by the naked eye. And this bioassay possessed high selectivity and stability making the developed detection method practically promising.

BioMOF-Based Anti-Cancer Drug Delivery Systems

A variety of nanomaterials have been developed specifically for biomedical applications, such as drug delivery in cancer treatment. These materials involve both synthetic and natural nanoparticles and nanofibers of varying dimensions. The efficacy of a drug delivery system (DDS) depends on its biocompatibility, intrinsic high surface area, high interconnected porosity, and chemical functionality. Recent advances in metal-organic framework (MOF) nanostructures have led to the achievement of these desirable features. MOFs consist of metal ions and organic linkers that are assembled in different geometries and can be produced in 0, 1, 2, or 3 dimensions. The defining features of MOFs are their outstanding surface area, interconnected porosity, and variable chemical functionality, which enable an endless range of modalities for loading drugs into their hierarchical structures. MOFs, coupled with biocompatibility requisites, are now regarded as highly successful DDSs for the treatment of diverse diseases. This review aims to present the development and applications of DDSs based on chemically-functionalized MOF nanostructures in the context of cancer treatment. A concise overview of the structure, synthesis, and mode of action of MOF-DDS is provided.

ZIF-8 integrated with polydopamine coating as a novel nano-platform for skin-specific drug delivery

Metal-organic frameworks (MOFs) are highly promising as a novel class of drug delivery carriers; however, there are few reports about their application in nanoparticle-based formulations for dermal administration. In this work, we developed a novel kind of nanoparticular system based on zeolitic imidazolate framework-8 (ZIF-8) and polydopamine (PDA) modification for improving the dermal delivery of 5-fluorouracil (5-FU). The structures and properties of the prepared nanoparticles were characterized using a variety of analytical methods. Their ex vivo delivery performance in the skin was investigated using Franz cells, and the underlying mechanisms were studied via confocal laser scanning microscopy (CLSM) and hematoxylin-eosin (HE) experiments which were employed to probe the penetration pathway and the interaction between nanoparticles and the skin. The results revealed that both 5-FU@ZIF-8 and ZIF-8@5-FU@PDA had an enhancement effect on the deposition of 5-FU in the skin, and the surface coating of PDA could further reduce drug permeation across the skin, especially in the case of impaired skin, in comparison with the drug solution. The CLSM study using rhodamine 6G as the fluorescent probe to mimic 5-FU indicated that ZIF-8 and ZIF-8@PDA could deliver their payloads into the skin via two pathways, i.e., intercellular and follicular ones, and the follicular route was shown to be particularly important for ZIF-8@PDA, in which the drug and carrier were co-delivered into the skin as an intact particle. This study provides evidence for using ZIF-8 and PDA modification for skin-specific drug delivery and offers an effective avenue to develop novel nanoplatforms for dermal application to treat skin diseases.

Biomimetic photosensitizer nanocrystals trigger enhanced ferroptosis for improving cancer treatment

As a novel non-apoptotic cell death pathway, ferroptosis can effectively enhance the antitumor effects of photodynamic therapy (PDT) by disrupting intracellular redox homeostasis. However, the reported nanocomposites that combined the PDT and ferroptosis are cumbersome to prepare, and the unfavorable tumor microenvironment also severely interferes with their tumor suppressive effects. To address this inherent barrier, this study attempted to explore photosensitizers that could activate ferroptosis pathway and found that the photosensitizer aloe-emodin (AE) could induce cellular ferroptosis based on its specific inhibiting activity to Glutathione S-transferase P1(GSTP1), a key protein for ferroptosis. Herein, we prepared AE@RBC/Fe nanocrystals (NCs) with synergistic PDT and ferroptosis therapeutic effects by one-step emulsification to obtain AE NCs cores and further modification of red blood cells (RBC) membranes and ferritin. Benefiting from the involvement of ferritin, the prepared AE@RBC/Fe NCs provide not only sufficient oxygen for oxygen-dependent PDT, but also Fe3+ for iron-dependent ferroptosis in tumor cells. Furthermore, the biomimetic surface functionalization facilitated the prolonged circulation and cancer targeting of AE@RBC/Fe NCs in vivo. The in vitro and in vivo results demonstrate that AE@RBC/Fe NCs exhibit significantly enhanced therapeutic effects for the combined two antitumor mechanisms and provide a promising prospect for achieving PDT/ferroptosis synergistic therapy.

Biomolecule-mimetic nanomaterials for photothermal and photodynamic therapy of cancers: Bridging nanobiotechnology and biomedicine

Nanomaterial-based phototherapy has become an important research direction for cancer therapy, but it still to face some obstacles, such as the toxic side effects and low target specificity. The biomimetic synthesis of nanomaterials using biomolecules is a potential strategy to improve photothermal therapy (PTT) and photodynamic therapy (PDT) techniques due to their endowed biocompatibility, degradability, low toxicity, and specific targeting. This review presents recent advances in the biomolecule-mimetic synthesis of functional nanomaterials for PTT and PDT of cancers. First, we introduce four biomimetic synthesis methods via some case studies and discuss the advantages of each method. Then, we introduce the synthesis of nanomaterials using some biomolecules such as DNA, RNA, protein, peptide, polydopamine, and others, and discuss in detail how to regulate the structure and functions of the obtained biomimetic nanomaterials. Finally, potential applications of biomimetic nanomaterials for both PTT and PDT of cancers are demonstrated and discussed. We believe that this work is valuable for readers to understand the mechanisms of biomimetic synthesis and nanomaterial-based phototherapy techniques, and will contribute to bridging nanotechnology and biomedicine to realize novel highly effective cancer therapies.

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.

A pH-Responsive Cluster Metal-Organic Framework Nanoparticle for Enhanced Tumor Accumulation and Antitumor Effect

As a result of the deficient tumor-specific antigens, potential off-target effect, and influence of protein corona, metal-organic framework nanoparticles have inadequate accumulation in tumor tissues, limiting their therapeutic effects. In this work, a pH-responsive linker (L) is prepared by covalently modifying oleylamine (OA) with 3-(bromomethyl)-4-methyl-2,5-furandione (MMfu) and poly(ethylene glycol) (PEG). Then, the L is embedded into a solid lipid nanoshell to coat apilimod (Ap)-loaded zeolitic imidazolate framework (Ap-ZIF) to form Ap-ZIF@SLN#L. Under the tumor microenvironment, the hydrophilic PEG and MMfu are removed, exposing the hydrophobic OA on Ap-ZIF@SLN#L, increasing their uptake in cancer cells and accumulation in the tumor. The ZIF@SLN#L nanoparticle induces reactive oxygen species (ROS). Ap released from Ap-ZIF@SLN#L significantly promotes intracellular ROS and lactate dehydrogenase generation. Ap-ZIF@SLN#L inhibits tumor growth, increases the survival rate in mice, activates the tumor microenvironment, and improves the infiltration of macrophages and T cells in the tumor, as demonstrated in two different tumor-bearing mice after injections with Ap-ZIF@SLN#TL. Furthermore, mice show normal tissue structure of the main organs and the normal serum level in alanine aminotransferase and aspartate aminotransferase after treatment with the nanoparticles. Overall, this pH-responsive targeting strategy improves nanoparticle accumulation in tumors with enhanced therapeutic effects.

MMP-2 Inhibitor-Mediated Tumor Microenvironment Regulation Using a Sequentially Released Bio-Nanosystem for Enhanced Cancer Photo-Immunotherapy

Combining photodynamic therapy (PDT) with natural killer (NK) cell-based immunotherapy has shown great potential against cancers, but the shedding of NK group 2, member D ligands (NKG2DLs) on tumor cells inhibited NK cell activation in the tumor microenvironment. Herein, we assembled microenvironment-/light-responsive bio-nanosystems (MLRNs) consisting of SB-3CT-containing β-cyclodextrins (β-CDs) and photosensitizer-loaded liposomes, in which SB-3CT was considered to remodel the tumor microenvironment. β-CDs and liposomes were linked by metalloproteinase 2 (MMP-2) responsive peptides, enabling sequential release of SB-3CT and chlorin e6 triggered by the MMP-2-abundant tumor microenvironment and 660 nm laser irradiation, respectively. Released SB-3CT blocked tumor immune escape by antagonizing MMP-2 and promoting the NKG2D/NKG2DL pathway, while liposomes were taken up by tumor cells for PDT. MLRN-mediated photo-immunotherapy significantly induced melanoma cell cytotoxicity (83.31%), inhibited tumor growth (relative tumor proliferation rate: 1.13% of that of normal saline) in the xenografted tumor model, and enhanced tumor-infiltrating NK cell (148 times) and NKG2DL expression (9.55 and 16.52 times for MICA and ULBP-1, respectively), achieving a synergistic effect. This study not only provided a simple insight into the development of new nanomedicine for programed release of antitumor drugs and better integration of PDT and immunotherapy but also a novel modality for clinical NK cell-mediated immunotherapy against melanoma.

Recent advances in nano-drug delivery systems for synergistic antitumor immunotherapy

Immunotherapy has demonstrated great clinical success in the field of oncology in comparison with conventional cancer therapy. However, cancer immunotherapy still encounters major challenges that limit its efficacy against different types of cancers and the patients show minimal immune response to the immunotherapy. To overcome these limitations, combinatorial approaches with other therapeutics have been applied in the clinic. Simultaneously, nano-drug delivery system has played an important role in increasing the antitumor efficacy of various treatments and has been increasingly utilized for synergistic immunotherapy to further enhance the immunogenicity of the tumors. Specifically, they can promote the infiltration of immune cells within the tumors and create an environment that is more sensitive to immunotherapy, particularly in solid tumors, by accelerating tumor accumulation and permeability. Herein, this progress report provides a brief overview of the development of nano-drug delivery systems, classification of combinatory cancer immunotherapy and recent progress in tumor immune synergistic therapy in the application of nano-drug delivery systems.

Nanocarriers for intracellular co-delivery of proteins and small-molecule drugs for cancer therapy

In the past few decades, the combination of proteins and small-molecule drugs has made tremendous progress in cancer treatment, but it is still not satisfactory. Because there are great differences in molecular weight, water solubility, stability, pharmacokinetics, biodistribution, and the ways of release and action between macromolecular proteins and small-molecule drugs. To improve the efficacy and safety of tumor treatment, people are committed to developing protein and drug co-delivery systems. Currently, intracellular co-delivery systems have been developed that integrate proteins and small-molecule drugs into one nanocarrier via various loading strategies. These systems significantly improve the blood stability, half-life, and biodistribution of proteins and small-molecule drugs, thus increasing their concentration in tumors. Furthermore, proteins and small-molecule drugs within these systems can be specifically targeted to tumor cells, and are released to perform functions after entering tumor cells simultaneously, resulting in improved effectiveness and safety of tumor treatment. This review summarizes the latest progress in protein and small-molecule drug intracellular co-delivery systems, with emphasis on the composition of nanocarriers, as well as on the loading methods of proteins and small-molecule drugs that play a role in cells into the systems, which have not been summarized by others so far.

Catalase-Like Nanozymes: Classification, Catalytic Mechanisms, and Their Applications

The field of nanozymes has developed rapidly over the past decade. Among various oxidoreductases mimics, catalase (CAT)-like nanozyme, acting as an essential part of the regulation of reactive oxygen species (ROS), has attracted extensive research interest in recent years. However, CAT-like nanozymes are not as well discussed as other nanozymes such as peroxidase (POD)-like nanozymes, etc. Compared with natural catalase or artificial CAT enzymes, CAT-like nanozymes have unique properties of low cost, size-dependent properties, high catalytic activity and stability, and easy surface modification, etc., which make them widely used in various fields, especially in tumor therapy and disease treatment. Consequently, there is a great requirement to make a systematic discussion on CAT-like nanozymes. In this review, some key aspects of CAT-like nanozymes are deeply summarized as: 1) Typical CAT-like nanozymes classified by different nanomaterials; 2) The catalytic mechanisms proposed by experimental and theoretical studies; 3) Extensive applications in regard to tumor therapy, cytoprotection and sensing. Therefore, it is prospected that this review will contribute to the further design of CAT-like nanozymes and optimize their applications with much higher efficiency than before.

pH-Responsive hyaluronic acid-enveloped ZIF-8 nanoparticles for anti-atherosclerosis therapy

Nanomedicines represent new promising strategies for treating atherosclerosis (AS), because they enhance drug bioavailability and have lower side effects. Nevertheless, nanomedicines have several challenges with these advantages, including a limited circulation life, lack of precise targeting, and insufficient control of drug release. Accordingly, the development of drug delivery systems (DDSs) with abilities to enhance the payload delivery to the AS plaque lesion and to control drug release can boost the therapeutic efficacy and safety for AS treatment. Herein, we employed a one-step self-assembly approach for effectively encapsulating the anti-AS drug simvastatin (SIM) in zeolitic imidazolate framework-8 (ZIF-8) (SIM/ZIF-8), and then coated it with hyaluronic acid (HA) to fabricate the SIM/ZIF-8@HA nanoplatform. The resulting nanoplatform could efficiently accumulate in plaque regions through the specific recognition between HA and CD44. Meanwhile, the acid environment breaks down ZIF-8 to release SIM. The in vitro and in vivo experiments demonstrated that SIM/ZIF-8@HA could inhibit the proliferation of smooth muscle cells and have good biocompatibility. Moreover, SIM/ZIF-8@HA can effectively suppress the development of AS plaques without any considerable side effects in mice treatments. The findings revealed that SIM/ZIF-8@HA may be a promising nanomedicine for safe and efficient anti-AS applications.

The uptake of metal-organic frameworks: a journey into the cell

The application of metal-organic frameworks (MOFs) in drug delivery has advanced rapidly over the past decade, showing huge progress in the development of novel systems. Although a large number of versatile MOFs that can carry and release multiple compounds have been designed and tested, one of the main limitations to their translation to the clinic is the limited biological understanding of their interaction with cells and the way they penetrate them. This is a crucial aspect of drug delivery, as MOFs need to be able not only to enter into cells but also to release their cargo in the correct intracellular location. While small molecules can enter cells by passive diffusion, nanoparticles (NPs) usually require an energy-dependent process known as endocytosis. Importantly, the fate of NPs after being taken up by cells is dependent on the endocytic pathways they enter through. However, no general guidelines for MOF particle internalization have been established due to the inherent complexity of endocytosis as a mechanism, with several factors affecting cellular uptake, namely NP size and surface chemistry. In this review, we cover recent advances regarding the understanding of the mechanisms of uptake of nano-sized MOFs (nanoMOFs)s, their journey inside the cell, and the importance of biological context in their final fate. We examine critically the impact of MOF physicochemical properties on intracellular trafficking and successful cargo delivery. Finally, we highlight key unanswered questions on the topic and discuss the future of the field and the next steps for nanoMOFs as drug delivery systems.

Applications of nanocomposites based on zeolitic imidazolate framework-8 in photodynamic and synergistic anti-tumor therapy

Due to the limitations resulting from hypoxia and the self-aggregation of photosensitizers, photodynamic therapy (PDT) has not been applied clinically to treat most types of solid tumors. Zeolitic imidazolate framework-8 (ZIF-8) is a common metal-organic framework that has ultra-high porosity, an adjustable structure, good biocompatibility, and pH-induced biodegradability. In this review, we summarize the applications of ZIF-8 and its derivatives in PDT. This review is divided into two parts. In the first part, we summarize progress in the application of ZIF-8 to enhance PDT and realize theranostics. We discuss the use of ZIF-8 to avoid the self-aggregation of photosensitizers, alleviate hypoxia, increase the PDT penetration depth, and combine PDT with multi-modal imaging. In the second part, we summarize how ZIF-8 can achieve synergistic PDT with other anti-tumor therapies, including chemotherapy, photothermal therapy, chemodynamic therapy, starvation therapy, protein therapy, gene therapy, and immunotherapy. Finally, we highlight the challenges that must be overcome for ZIF-8 to be widely applied in PDT. To the best of our knowledge, this is the first review of ZIF-8-based nanoplatforms for PDT.

Triarylboron-Based High Photosensitive Probes for Apoptosis Detection, Tumor-Targeted Imaging, and Selectively Inducing Apoptosis of Tumor Cells by Photodynamics

Herein, a series of triarylboron-based fluorescent probes were developed for distinguishing apoptosis from living cells and even necrosis. They also demonstrate high photosensitivity because they can produce detectable reactive oxygen species (ROS) under an ultra-low light power density (1.5 mW/cm²). By changing the peripheral groups to regulate the performance, we identified a multifunctional probe, TAB-6-amyl, which can be used not only for selectively imaging apoptosis but also for the targeted imaging of SKOV-3 cells in vitro and in vivo. It could further specifically induce the apoptosis of SKOV-3 cells under light irradiation. During the study, we also found that TAB-6-amyl can cross the blood-brain barrier (BBB). Therefore, another probe based on this kind of structure, TAB-5-M-1-cRGD, was constructed for the targeted imaging of brain glioma cells and inducing their apoptosis. This study offers some promising tools for apoptosis detection and tumor photodynamic therapy (PDT).

Recent advances in ZnO-based photosensitizers: Synthesis, modification, and applications in photodynamic cancer therapy

Zinc oxide nanoparticles (ZnO NPs) are important semiconductor materials with interesting photo-responsive properties. During the past, ZnO-based NPs have received considerable attention for photodynamic therapy (PDT) due to their biocompatibility and excellent potential of generating tumor-killing reactive oxygen species (ROS) through gentle photodynamic activation. This article provides a comprehensive review of the recent developments and improvements in optical properties of ZnO NPs as photosensitizers for PDT. The optical properties of ZnO-based photosensitizers are significantly dependent on their charge separation, absorption potential, band gap engineering, and surface area, which can be adjusted/tuned by doping, compositing, and morphology control. Here, we first summarize the recent progress in the charge separation capability, absorption potential, band gap engineering, and surface area of nanosized ZnO-based photosensitizers. Then, morphology control that is closely related to their synthesis method is discussed. Following on, the state-of-art for the ZnO-based NPs in the treatment of hypoxic tumors is comprehensively reviewed. Finally, we provide some outlooks on common targeted therapy methods for more effective tumor killing, including the attachment of small molecules, antibodies, ligands molecules, and receptors to NPs which further improve their selective distribution and targeting, hence improving the therapeutic effectiveness. The current review may provide useful guidance for the researchers who are interested in this promising dynamic cancer treatment technology.

Remodeling Tumor-Associated Neutrophils to Enhance Dendritic Cell-Based HCC Neoantigen Nano-Vaccine Efficiency

Hepatocellular carcinoma (HCC) commonly emerges in an immunologically "cold" state, thereafter protects it away from cytolytic attack by tumor-infiltrating lymphocytes, resulting in poor response to immunotherapy. Herein, an acidic/photo-sensitive dendritic cell (DCs)-based neoantigen nano-vaccine has been explored to convert tumor immune "cold" state into "hot", and remodel tumor-associated neutrophils to potentiate anticancer immune response for enhancing immunotherapy efficiency. The nano-vaccine is constructed by SiPCCl2 -hybridized mesoporous silica with coordination of Fe(III)-captopril, and coating with exfoliated membrane of matured DCs by H22-specific neoantigen stimulation. The nano-vaccines actively target H22 tumors and induce immunological cell death to boost tumor-associated antigen release by the generation of excess 1 O2 through photodynamic therapy, which act as in situ tumor vaccination to strengthen antitumor T-cell response against primary H22 tumor growth. Interestingly, the nano-vaccines are also home to lymph nodes to directly induce the activation and proliferation of neoantigen-specific T cells to suppress the primary/distal tumor growth. Moreover, the acidic-triggered captopril release in tumor microenvironment can polarize the protumoral N2 phenotype neutrophils to antitumor N1 phenotype for improving the immune effects to achieve complete tumor regression (83%) in H22-bearing mice and prolong the survival time. This work provides an alternative approach for developing novel HCC immunotherapy strategies.

Bone-Targeted ICG/Cyt c@ZZF-8 Nanoparticles Based on the Zeolitic Imidazolate Framework-8: A New Synergistic Photodynamic and Protein Therapy for Bone Metastasis

Bone metastasis (BM) is a solid tumor confined to narrow bone marrow cavities with a relatively poor blood supply and hypoxic environment, making conventional anticancer treatments difficult. In our study,...

ZIF-8 with cationic defects toward efficient 125I2 uptake for in vitro radiotherapy of colon cancer

Introducing 2,3-dimethyl-1H-imidazol-3-ium iodide (Dmim) as a monodentate ligand during the preparation of ZIF-8 yields ZIF-8+(50) and ZIF-8+(38) with cationic ‘missing linker’ defects. ZIF-8+(38) adsorbs 125I2 and the resulting radioactive host-guest...

Monodisperse ZIF-8@dextran nanoparticles co-loaded with hydrophilic and hydrophobic functional cargos for combined near-infrared fluorescence imaging and photothermal therapy

Impressive developments have been achieved with the use of zeolitic imidazolate framework-8 (ZIF-8) as nanocarriers for tumor theranostics in recent decades by incorporating imaging agents and therapeutic drugs within ZIF-8. However, the simultaneous immobilization of hydrophilic and hydrophobic functional molecules into ZIF-8 nanoparticles in water or organic solvents still presents a daunting challenge. Herein, we developed a new synthesis/encapsulation two-in-one (denoted as one-pot) approach to synthesize uniform dextran-modified Cy5.5&ICG@ZIF-8-Dex nanoparticles in DMSO/H₂O solvent mixtures, which enabled the simultaneous encapsulation of hydrophilic indocyanine green (ICG) and hydrophobic cyanine-5.5 (Cy5.5) during the same step. It was confirmed that the one-pot approach in this mixed solvents facilitated the loading of ICG and Cy5.5 molecules. Moreover, the encapsulation of Cy5.5 and ICG within ZIF-8 nanoparticles endowed them with fluorescence imaging capability and photothermal conversion capacity, respectively. The in vivo near-infrared (NIR) fluorescent images of A549-bearing mice injected with Cy5.5&ICG@ZIF-8-Dex demonstrated sufficient accumulations of Cy5.5 at tumor sites due to the enhanced permeability and retention effect. Most impressively, the fluorescent intensity of Cy5.5&ICG@ZIF-8-Dex at tumor site was approximately 40-fold higher than that of free Cy5.5. Additionally, the results of in vivo infrared imaging and photothermal therapy of Cy5.5&ICG@ZIF-8-Dex showed enhanced therapeutic efficiency in comparison with free ICG, further confirming its tumor-targeting capability and photothermal capacity. Therefore, this multifunctional system based on ZIF-8 nanocarriers offered a potential nanoplatform for tumor-targeting theranostics, thus broadening the synthesis and applications of ZIF-8 composite nanoparticles for NIR fluorescence imaging and photothermal therapy in the biomedical field. STATEMENT OF SIGNIFICANCE: Simultaneous immobilization of hydrophilic and hydrophobic molecules into ZIF-8 nanoparticles still remains a daunting challenge. Therefore, we have developed a new synthesis/encapsulation two-in-one approach to synthesize uniform Cy5.5&ICG@ZIF-8-Dex composite nanoparticles in DMSO/H₂O solvent mixtures, which enabled the simultaneous encapsulation of hydrophilic indocyanine green (ICG) and hydrophobic cyanine-5.5 (Cy5.5) functional molecules during a single step. The results showed that the co-loading of Cy5.5 and ICG within the ZIF-8 nanoparticles endowed them with a remarkable fluorescence imaging capability and photothermal conversion capacity. Based on their enhanced convenience and efficacy to simultaneously encapsulate hydrophilic and hydrophobic molecules, the multifunctional nanocarriers that were prepared in the DMSO/H₂O mixed solvents provide a potential nanoplatform toward fluorescence imaging and photothermal therapy for tumor theranostics.

Molecular-engineered highly photosensitive triarylphosphine oxide compounds for apoptosis imaging and selectively inducing apoptosis of tumor cells by photodynamic therapy

Although photodynamic therapy (PDT) has wide applications, tumor-targeting probes with high photosensitivity or apoptosis-monitoring capability are still scarce, which possess low phototoxicity and can be used for evaluating the therapeutic...

Metal-organic frameworks (MOFs) as host materials for the enhanced delivery of biomacromolecular therapeutics

Biomacromolecular drugs have become an important class of therapeutic agents for the treatment of human diseases. Considering their high propensity for being degraded in the human body, the choice of an appropriate delivery system is key to ensure the therapeutic efficacy of biomacromolecular drugs in vivo. As an emerging class of supramolecular "host" materials, metal-organic frameworks (MOFs) exhibit advantages in terms of the tunability of pore size, encapsulation efficiency, controllable drug release, simplicity in surface functionalization and good biocompatibility. As a result, MOF-based host-guest systems have been extensively developed as a new class of flexible and powerful platform for the delivery of therapeutic biomacromolecules. In this review, we summarize current research progress in the synthesis of MOFs as delivery materials for a variety of biomacromolecules. Firstly, we briefly introduce the advances made in the use of biomacromolecular drugs for disease therapy and the types of commonly used clinical delivery systems. We then describe the advantages of using MOFs as delivery materials. Secondly, the strategies for the construction of MOF-encapsulated biomacromolecules (Biomacromolecules@MOFs) and the release mechanisms of the therapeutics are categorized. Thirdly, the application of MOFs to deliver different types of biomacromolecules (e.g., antigens/antibodies, enzymes, therapeutic proteins, DNA/RNA, polypeptides, and polysaccharides) for the treatment of various human diseases based on immunotherapy, gene therapy, starvation therapy and oxidation therapy is summarized. Finally, the remaining challenges and available opportunities for MOFs as drug delivery systems are outlined, which we anticipate will encourage additional research efforts directed towards developing Biomacromolecules@MOFs systems for biomedical applications.

Integrating Porphyrinic Metal-Organic Frameworks in Nanofibrous Carrier for Photodynamic Antimicrobial Application

The rise and spread of antimicrobial resistance is creating an ever greater challenge in wound management. Nanofibrous membranes (NFMs) incorporated with antibiotics have been widely used to remedy bacterial wound infections owing to their versatile features. However, misuse of antibiotics has resulted in drug resistance, and it remains a significant challenge to achieve both high antibacterial efficiency and without causing bacterial resistance. Here, the ‘MOF-first’ strategy was adopted, the porphyrinic metal-organic frameworks nanoparticles (PCN−224 NPs) were pre-synthesized first, and then the composite antibacterial PCN−224 NPs @ poly (ε-caprolactone) (PM) NFMs were fabricated via a facile co-electrospinning technology. This strategy allows large amounts of effective MOFs to be integrated into nanofibers to effectively eliminate bacteria without bacterial resistance and to realize a relatively fast production rate. Upon visible light (630 nm) irradiation for 30 min, the PM−25 NFMs have the best ¹O₂ generation performance, triggering remarkable photodynamic antibacterial effects against both S. aureus, MRSA, and E. coli bacteria with survival rates of 0.13%, 1.91%, and 2.06% respectively. Considering the photodynamic antibacterial performance of the composite nanofibrous membranes functionalized by porphyrinic MOFs, this simple approach may provide a feasible way to use MOF materials and biological materials to construct wound dressing with the versatility to serve as an antibacterial strategy in order to prevent bacterial resistance.

Engineered Red Blood Cell Biomimetic Nanovesicle with Oxygen Self-Supply for Near-Infrared-II Fluorescence-Guided Synergetic Chemo-Photodynamic Therapy against Hypoxic Tumors

The low bioavailability of photosensitizers (PSs) and the hypoxia nature of tumors often limit the efficacy of current photodynamic therapy (PDT). Therefore, improving the utilization of three essential components (PS, light, and O2) in tumors will enhance PDT efficacy substantially. Herein, we have developed a red blood cell (RBC) biomimetic theranostic nanovesicle (named SPN-Hb@RBCM) with improved photostability, accumulation of PSs, and oxygen self-supply ability to enhance PDT efficacy upon near-infrared (NIR) laser irradiation. Such a biomimetic nanovesicle was prepared by a red blood cell membrane (RBCM)-camouflaged hemoglobin (Hb)-linked semiconducting polymer nanoparticle (SPN-Hb). The RBCM coating enables the long-term circulation of SPN-Hb due to the membrane-mediated immune evasion, allowing for more effective PS accumulation in tumors. Under 808 nm laser irradiation, the photostable SPN can serve as both a photodynamic and a second-near-infrared-window (NIR-II) fluorescence imaging agent; meanwhile, the conjugated Hb can be used as an oxygen carrier to relieve tumor hypoxia for enhancing PDT efficacy. In addition, Hb can also react with the tumor microenvironment overproduced H2O2 to generate cytotoxic hydroxyl radicals (•OHs) for chemodynamic therapy (CDT), which further achieve synergistic effects for PDT. Thus, this study proposed a promising biomimetic theranostic nanoagent for enhancing tumor oxygenation and NIR-II fluorescence-guided synergetic CDT/PDT against hypoxic tumors.

Metal-Organic Framework Nanoparticles Power DNAzyme Logic Circuits for Aberrant MicroRNA Imaging

At the molecular level, a large number of studies exist on the use of dynamic DNA molecular circuits for disease diagnosis and biomedicine. However, how to design programmable molecular circuit devices to autonomously and accurately diagnose multiple low-abundance biomolecules in complex cellular environments remains a challenge. Here, we constructed DNAzyme logic circuits for the analysis and imaging of multiple microRNAs in living cells using Cu/ZIF-8 NPs as a nanocarrier of the logic gate modules and the Cu²⁺ cofactor of the Cu²⁺-dependent DNAzyme. The logic gate modules of the logic operation system were adsorbed on the surface of Cu/ZIF-8 NPs via electrostatic interaction. After internalization, pH-responsive Cu/ZIF-8 NPs could efficiently release the logic gate modules and Cu²⁺, which allowed us to realize multiple logic computations initiated by endogenous miRNA, including one YES logic gate and two binary logic gates (OR and AND) in different living cells. Cu²⁺-DNAzyme logic circuits could quickly respond to multiple endogenous miRNAs in the complex cell environment, which also provided a new research method for the application of DNA biocomputing circuits in living cells.

A multimodal strategy of Fe3O4@ZIF-8/GOx@MnO2 hybrid nanozyme via TME modulation for tumor therapy

Weak acidity (6.5-6.9) and limited H₂O₂ level in the tumor microenvironment (TME) usually impact the therapeutic effect of chemodynamic therapy (CDT) for cancer. A Specific TME promotes the formation of an immunosuppressive microenvironment and results in high rate of recurrence and metastasis of cancer. Fe₃O₄@ZIF-8/GOx@MnO₂ multi-layer core shell nanostructure was constructed as a hybrid nanozyme. After magnetic targeting of the tumor site, the outermost MnO₂ shell catalyzed H₂O₂ in TME to produce O₂ and was broken due to the reaction with glutathione. Due to the acid response, the ZIF-8 layer would crack and release glucose oxidase (GOx) and Fe₃O₄. The generated O₂ was utilized by GOx in starvation therapy to consume glucose and produce H₂O₂ and gluconic acid. The Fenton reaction efficiency of Fe(II) was improved by the increased H₂O₂ concentration and the enhanced acidity in TME. At the same time, the intrinsic photothermal effect of Fe₃O₄ upon 808 nm laser irradiation promoted the activity of MnO₂ and GOx as oxidase, and Fe(II) as catalase-like, and ablated the primary tumor. Moreover, the hybrid nanozyme can facilitate the transformation of M2-type macrophages to M1-type, and strong systemic antitumor immune effect was induced. A synergy of multiple therapeutic modes including starvation therapy, CDT, photothermal therapy (PTT), and immunotherapy can be realized in the hybrid nanozyme for tumor therapy.