One-pot Synthesis of Metal-Organic Frameworks with Encapsulated Target Molecules and Their Applications for Controlled Drug Delivery

Growth of ZIF-8 Nanoparticles In Situ on Graphene Oxide Nanosheets: A Multifunctional Nanoplatform for Combined Ion-Interference and Photothermal Therapy

The regulation of intracellular ions' overload to interrupt normal bioprocesses and cause cell death has been developed as an efficient strategy (named as ion-interference therapy/IIT) to treat cancer. In this study, we design a multifunctional nanoplatform (called BSArGO@ZIF-8 NSs) by in situ growth of metal organic framework nanoparticles (ZIF-8 NPs) onto the graphene oxide (GO) surface, subsequently reduced by ascorbic acid and modified by bovine serum albumin. This nanocomplex causes the intracellular overload of Zn²⁺, an increase of reactive oxygen species (ROS), and exerts a broad-spectrum lethality to different kinds of cancer cells. BSArGO@ZIF-8 NSs can promote cell apoptosis by initiating bim (a pro-apoptotic protein)-mediated mitochondrial apoptotic events, up-regulating PUMA/NOXA expression, and down-regulating the level of Bid/p53AIP1. Meanwhile, Zn²⁺ excess triggers cellular dysfunction and mitochondria damage by activating the autophagy signaling pathways and disturbing the intracellular environmental homeostasis. Combined with the photothermal effect of reduced GO (rGO), BSArGO@ZIF-8 NSs mediated ion-interference and photothermal combined therapy leads to effective apoptosis and inhibits cell proliferation and angiogenesis, bringing a higher efficacy in tumor suppression in vivo. This designed Zn-based multifunctional nanoplatform will allow promoting further the development of IIT and the corresponding combined cancer therapy strategy.

Research Progress Based on Regulation of Tumor Microenvironment Redox and Drug-Loaded Metal-Organic Frameworks

The process of tumor growth and deterioration is accompanied by increased oxygen free radicals, high glutathione concentration, hypoxia, and poor drug targeting during treatment, limiting the treatment of tumors. Metal-organic framework (MOF) preparations are continuously being developed and applied in tumor therapy. In this paper, the design and application of reactive oxygen species (ROS) and redox drug-loaded MOF preparations are reviewed. Moreover, the research challenges and application prospects of MOFs in tumor therapy are also discussed.

Modified gelatin/iron- based metal-organic framework nanocomposite hydrogel as wound dressing: Synthesis, antibacterial activity, and Camellia sinensis release

A new kind of Camellia sinensis-loaded nanocomposite hydrogel based on modified gelatin/iron-metal-organic framework was developed as an antibacterial wound dressing. Gelatin as a biocompatible natural polymer was modified with methacrylate anhydride to produce gelatin methacrylate. Thereafter, acrylic acid and acrylamide were grafted on gelatin methacrylate during an aqueous polymerization process. To enhance the porosity, mechanical strength, and drug loading capability of the hydrogel and reduce its toxicity, iron- based metal-organic framework was incorporated within the hydrogel. To add more functionality to the final wound dressing, Camellia sinensis, an antibacterial herbal drug was loaded on the hydrogel. The structural and chemical properties of prepared nanocomposite hydrogel were investigated by FTIR, XRD, SEM, and TGA techniques. The incorporation of iron-based metal-organic framework within the hydrogel matrix led to an increase in its water absorption value from 400.10 to 547.96 (g/g). The release study of Camellia sinensis (CS) extract from the prepared nanocomposite hydrogel exhibited a sustained release manner. The antibacterial test revealed the nanocomposite hydrogel contain extract has an effective antibacterial function against "Bacillus serous", "Staphylococcus aureus", "Streptococcus mutans"," Escherichia coli", "Klebsiella pneumoniae", and "Pseudomonas aeruginosa" bacteria. Therefore, the synthesized nanocomposite is a good candidate as an antibacterial hydrogel wound dressing. .

Mesenchymal Stem Cell-Derived Extracellular Vesicles for Bone Defect Repair

The repair of critical bone defects is a hotspot of orthopedic research. With the development of bone tissue engineering (BTE), there is increasing evidence showing that the combined application of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) (MSC-EVs), especially exosomes, with hydrogels, scaffolds, and other bioactive materials has made great progress, exhibiting a good potential for bone regeneration. Recent studies have found that miRNAs, proteins, and other cargo loaded in EVs are key factors in promoting osteogenesis and angiogenesis. In BTE, the expression profile of the intrinsic cargo of EVs can be changed by modifying the gene expression of MSCs to obtain EVs with enhanced osteogenic activity and ultimately enhance the osteoinductive ability of bone graft materials. However, the current research on MSC-EVs for repairing bone defects is still in its infancy, and the underlying mechanism remains unclear. Therefore, in this review, the effect of bioactive materials such as hydrogels and scaffolds combined with MSC-EVs in repairing bone defects is summarized, and the mechanism of MSC-EVs promoting bone defect repair by delivering active molecules such as internal miRNAs is further elucidated, which provides a theoretical basis and reference for the clinical application of MSC-EVs in repairing bone defects.

NIR-PTT/ROS-Scavenging/Oxygen-Enriched Synergetic Therapy for Rheumatoid Arthritis by a pH-Responsive Hybrid CeO2-ZIF-8 Coated with Polydopamine

Rheumatoid arthritis (RA) is an inflammatory type of arthritis that causes joint pain and damage. The inflammatory cell infiltration (e.g., M1 macrophages), the poor O₂ supply at the joint, and the excess reactive oxygen species (ROS)-induced oxidative injury are the main causes of RA. We herein report a polydopamine (PDA)-coated CeO₂-dopped zeolitic imidazolate framework-8 (ZIF-8) nanocomposite CeO₂-ZIF-8@PDA (denoted as CZP) that can synergistically treat RA. Under near-infrared (NIR) light irradiation, PDA efficiently scavenges ROS and results in an increased temperature in the inflamed area because of its good light-to-heat conversion efficiency. The rise of temperature serves to obliterate hyper-proliferative inflammatory cells accumulated in the diseased area while vastly promoting the collapse of the acidic-responsive skeleton of ZIF-8 to release the encapsulated CeO₂. The released CeO₂ exerts its catalase-like activity to relieve hypoxia by generating oxygen via the decomposition of H₂O₂ highly expressed in the inflammatory sites. Thus, the constructed CZP composite can treat RA through NIR-photothermal/ROS-scavenging/oxygen-enriched combinative therapy and show good regression of pro-inflammatory cytokines and hypoxia-inducible factor-1α (HIF-1α) in vitro and promising therapeutic effect on RA in rat models. The multimodal nano-platform reported herein is expected to shed light on the design of synergistic therapeutic nanomedicine for effective RA therapy.

Copper-based metal-organic frameworks for biomedical applications

Metal-organic frameworks (MOFs) are a class of important porous, crystalline materials composed of metal ions (clusters) and organic ligands. Owing to the unique redox chemistry, photochemical and electrical property, and catalytic activity of Cu^2+/+, copper-based MOFs (Cu-MOFs) have been recently and extensively explored in various biomedical fields. In this review, we first make a brief introduction to the synthesis of Cu-MOFs and their composites, and highlight the recent synthetic strategies of two most studied representatives, three-dimensional HKUST-1 and two-dimensional Cu-TCPP. The recent advances of Cu-MOFs in the applications of cancer treatment, bacterial inhibition, biosensing, biocatalysis, and wound healing are summarized and discussed. Furthermore, we propose a prospect of the future development of Cu-MOFs in biomedical fields and beyond.

Zeolitic imidazolate framework-based nanoparticles for the cascade enhancement of cancer chemodynamic therapy by targeting glutamine metabolism

The reprogrammed amino acid metabolism maintains the powerful antioxidant defense and DNA damage repair capacity of cancer cells, which could promote their escape from reactive oxygen species (ROS)-induced damage and inevitably diminish the efficacy of ROS-based therapies. Herein, we propose a strategy to enhance the effect of chemodynamic therapy (CDT) via glutaminolysis-targeted inhibition for cancer cells dependent on abnormal glutamine metabolism. To screen optimum drugs targeting glutamine metabolism, transcriptomic analysis is performed to identify predictive biomarkers. Eventually, telaglenastat (CB-839) is used to block mitochondrial glutaminase 1 (GLS 1) in basal-like breast cancer and loaded into the developed iron-doped zeolitic imidazolate frameworks (ZIF(Fe) NPs) to form ZIF(Fe)&CB nanoparticles, which are able to co-deliver Fe²⁺ and CB-839 into the tumor. CB-839 induced-glutaminolysis inhibition not only reduces intracellular antioxidants (glutathione, taurine) to amplify Fe²⁺-induced oxidative stress, but also decreases nucleotide pools (e.g., adenosine, dihydroorotate) to incur the deficiency of building blocks for DNA damage repair, thereby promoting the cell-killing effect of CDT. In vivo assessments further confirm the enhanced anticancer performance and good biocompatibility of ZIF(Fe)&CB nanoparticles. This study provides a promising strategy for the development and improvement of ROS-based anticancer nanosystems.

Membrane Cholesterol Depletion Enhances Enzymatic Activity of Cell-Membrane-Coated Metal-Organic-Framework Nanoparticles

Metal-organic-framework nanoparticles (MOF NPs) have been increasingly used to encapsulate therapeutic enzymes for delivery. To better interface these MOF NPs with biological systems, researchers have coated them with natural cell membranes, enabling biomimicking properties suitable for innovative biomedical applications. Herein, we report that the enzymatic activity of cell-membrane-coated MOF NPs can be significantly enhanced by reducing membrane cholesterol content. We demonstrate such cholesterol-enzymatic activity correlation using zeolitic imidazolate framework-8 MOF NPs to encapsulate catalase, horseradish peroxidase, and organophosphate hydrolase, respectively. MOF NPs coated with membranes of human red blood cells or macrophages show similar outcomes, illustrating the broad applicability of this finding. The mechanistic investigation further reveals that reducing cholesterol levels effectively enhances membrane permeability likely responsible for the increased enzymatic activity. These results also imply a facile approach to tailoring the enzymatic activity of cell-membrane-coated MOF NPs by simply tuning the membrane cholesterol level.

Superoxide dismutase@zeolite Imidazolate Framework-8 Attenuates Noise-Induced Hearing Loss in Rats

Reactive oxygen species (ROS) and inflammation have been considered major contributors to noise-induced hearing loss (NIHL) that constituted a public health threat worldwide. Nanoantioxidants, with high antioxidant activity and good stability, have been extensively used in the study of ROS-related diseases. In this study, we constructed a superoxide dismutase (SOD)@zeolite imidazolate framework-8 (ZIF-8) nanoparticle based on biomimetic mineralization and applied it to a rat model of NIHL. Our results showed that SOD@ZIF-8 effectively protected the animals from hearing loss and hair cell loss caused by noise. ROS, oxidative damage, and inflammation of noise-damaged cochlea were attenuated considerably after SOD@ZIF-8 administration. Importantly, we found that SOD@ZIF-8 achieved nanotherapy for NIHL in rats via a primary effect on the Sirtuin-3 (SIRT3)/superoxide dismutase2 (SOD2) signaling pathway without obvious adverse side effects. Therefore, our study is expected to open up a new field for NIHL treatment, and lay a foundation for the application of nanomaterials in other ROS-related inner ear diseases.

Near-Infrared-II Plasmonic Trienzyme-Integrated Metal-Organic Frameworks with High-Efficiency Enzyme Cascades for Synergistic Trimodal Oncotherapy

Natural enzyme-based catalytic cascades hold great promise for cancer therapy, but their clinical utility is greatly hindered by the loss of their functions during in vivo delivery. Herein, a plasmonic trienzyme-integrated metal-organic framework (plasEnMOF) nanoplatform with high-efficiency enzyme cascades is reported for synergistic starvation, chemodynamic, and plasmonic hyperthermia trimodal therapy of hypoxic tumors. These plasEnMOFs are created with encapsulation of near-infrared-II (NIR-II) plasmonic Au nanorods and natural enzymes-catalase (CAT), glucose oxidase (GOx), and horseradish peroxidase (HRP) within zeolitic imidazolate framework-8 (ZIF-8) MOFs. As a trienzyme cascade system, the plasEnMOFs effectively deplete intratumoral glucose and generate toxic reactive oxygen species (ROS) for starvation therapy and chemodynamic therapy (CDT) combined with the plasmonic hyperthermia therapy (PHT). The enhanced glucose consumption and ROS generation by the NIR-II plasmonic photothermal effect are also demonstrated. The improved chemo- and thermotolerance of the encapsulated natural enzymes within the protective ZIF-8 MOFs are evidenced. With the integrated enzyme cascades and NIR-II photothermal effects, these plasEnMOFs are demonstrated with exceptional therapeutic effects on 4T1 xenograft tumors through the combined starvation/CDT/PHT therapy. This work highlights the superiority of natural enzyme cascade systems integrated in plasmonic MOFs for high-efficiency enzymatic cancer therapy.

Universal Strategy to Efficiently Coat Zeolitic Imidazolate Frameworks onto Diverse Substrates

Anchoring metal-organic framework (MOF) coating has attracted extensive interest due to its wide applications in drug delivery, gas storage and separation, catalysis, and so forth. Here, we reported a flexible strategy on generating ZIF-8 coatings onto diverse substrates in the scale up to hundreds cm2, independent of the geometry of the substrate, with controllable thickness, texture structure, and crystal size of coating. By understanding the mechanism and factors on the formation of ZIF-8 coatings, various zeolitic imidazolate framework coatings were successfully produced. This general strategy and in-depth insights pave the new highway to the design and synthesis of MOF coatings onto diverse substrates.

Hybrid liposome/metal-organic framework as a promising dual-responsive nanocarriers for anticancer drug delivery

In this work, liposome-coated iron (III) benzene-1,3,5-tricarboxylate (Fe-BTC) metal-organic framework is examined as a promising pH/Ultrasound dual-responsive nanocarriers for doxorubicin (DOX) delivery. The successful coating of the MOF particles (Lip-Fe-BTC) with the phospholipid bilayer (PBL) was established by direct fusion into the synthesized liposomes. The liposome coating was verified using several techniques, including dynamic light scattering (DLS) and transmission electron microscopy (TEM). The DLS measurements showed an increase in the average particle diameter of liposomes from 150 nm to 163.1 nm for Lip-Fe-BTC particles. The Fe-BTC particles had the highest average particle diameter (287.3 nm). These results demonstrated that the PBL reduced the aggregation of the particles and improved their dispersity in the release medium. The TGA results demonstrated the MOF's excellent thermal stability. Furthermore, the nanocarrier's loading efficiency and capacity were determined to be ~90% and ~13.5 wt%, respectively. The in-vitro DOX release experiments demonstrated that the DOX-loaded Fe-BTC and liposome-coated Fe-BTC particles showed good pH and US dual-responsive capability, making them promising nanocarriers for drug delivery. The application of US enhanced DOX release from both Fe-BTC and liposome-coated Fe-BTC. In the case of Fe-BTC-DOX particles, the application of US enhanced the DOX release to around 38% and 67%, at pH levels of 7.4 and 5.3, respectively. Similarly, DOX release from the Lip-Fe-BTC-DOX particles reached ~35% and ~53%, at pH levels of 7.4 and 5.3, respectively. The MTT assay showed the biocompatibility and low cytotoxicity of these nanocarriers below 100 µg/ml.

Overview of Application of Nanomaterials in Medical Domain

With the development of nanotechnology, the application of nanomaterials in the medical field has become a forefront hotspot in the field of scientific research in the 21st century. Compared with traditional drug carriers, drug carriers made of nanomaterials have advantages such as higher drug loading rate, better biocompatibility, and targeted transportation, which provide the possibility for the treatment of a variety of diseases. In this paper, the characteristics and advantages of nanomaterials as well as their applications in the medical field are reviewed and the research progress of nanomaterials is analyzed.

Stability of ZIF-8 Nanoparticles in Most Common Cell Culture Media

Zeolite imidazolate framework-8 (ZIF-8) is a promising platform for drug delivery, and information regarding the stability of ZIF-8 nanoparticles in cell culture media is essential for proper interpretation of in vitro experimental results. In this work, we report a quantitative investigation of the ZIF-8 nanoparticle's stability in most common cell culture media. To this purpose, ZIF-8 nanoparticles containing sterically shielded nitroxide probes with high resistance to reduction were synthesized and studied using electron paramagnetic resonance (EPR). The degradation of ZIF-8 in cell media was monitored by tracking the cargo leakage. It was shown that nanoparticles degrade at least partially in all studied media, although the degree of cargo leakage varies widely. We found a strong correlation between the amount of escaped cargo and total concentration of amino acids in the environment. We also established the role of individual amino acids in ZIF-8 degradation. Finally, 2-methylimidazole preliminary dissolved in cell culture media partially inhibits the degradation of ZIF-8 nanoparticles. The guidelines for choosing the proper cell culture medium for the in vitro study of ZIF-8 nanoparticles have been formulated.

Recent Research on Hybrid Hydrogels for Infection Treatment and Bone Repair

The repair of infected bone defects (IBDs) is still a great challenge in clinic. A successful treatment for IBDs should simultaneously resolve both infection control and bone defect repair. Hydrogels are water-swollen hydrophilic materials that maintain a distinct three-dimensional structure, helping load various antibacterial drugs and biomolecules. Hybrid hydrogels may potentially possess antibacterial ability and osteogenic activity. This review summarizes the recent progress of different kinds of antibacterial agents (including inorganic, organic, and natural) encapsulated in hydrogels. Several representative hydrogels of each category and their antibacterial mechanism and effect on bone repair are presented. Moreover, the advantages and disadvantages of antibacterial agent hybrid hydrogels are discussed. The challenge and future research directions are further prospected.

Role of CD47-SIRPα Checkpoint in Nanomedicine-Based Anti-Cancer Treatment

Many cancers have evolved various mechanisms to evade immunological surveillance, such as the inhibitory immune checkpoint of the CD47-SIRPα signaling pathway. By targeting this signaling pathway, researchers have developed diverse nanovehicles with different loaded drugs and modifications in anticancer treatment. In this review, we present a brief overview of CD47-SIRPα interaction and nanomedicine. Then, we delve into recent applications of the CD47-SIRPα interaction as a target for nanomedicine-based antitumor treatment and its combination with other targeting pathway drugs and/or therapeutic approaches.

MOF Hybrid for Long-Term Pest Management and Micronutrient Supply Triggered with Protease

Advanced intelligent systems for delivery of pesticides or fertilizers require formulations that allow for long-term efficacy. In this work, a metal-organic framework (MOF) hybrid was developed for long-term pest management and micronutrient supply. Zeolitic imidazolate framework-8 was fabricated for crop micronutrients (Zn²⁺) supply and insecticide dinotefuran (DNF) encapsulation. Polymethylmethacrylate was polymerized in situ to impart the MOF hybrid with sustained cargo delivery. Then, zein was introduced to facilitate protease-triggered cargo release associated with the microenvironment of pests and targeted release. The resulting MOF hybrid exhibited stimulus-responsive, slow-release behaviors. Sustained DNF delivery was achieved over a period of at least 32 days in soil. Compared with that of free DNF, the UV resistance of DNF in the MOF hybrid increased by nearly 10 times, and the insecticidal efficiency increased 33.3% with leaching treatment and 40.1% after incubating in a greenhouse for 14 days. This MOF hybrid provides a controlled, targeted, and sustained delivery formulation for long-term pest management and crop micronutrient supply and has huge application prospects in sustainable agriculture.

A multimodal Metal-Organic framework based on unsaturated metal site for enhancing antitumor cytotoxicity through Chemo-Photodynamic therapy

Chemodynamic therapy when combined with chemotherapy opens up a new avenue for treatment of cancer. However, its development is still restricted by low targeting, high dose and toxic side effects. Herein, rational designing and construction of a new multifunctional platform with the core-shell structure 5-ALA@UiO-66-NH-FAM@CP1 (ALA = 5-aminolevulinic acid, CP1 = zirconium-pemetrexed (Zr-MTA)) has been performed. In this platform, CP1 acting as a shell is encapsulated with the UiO-66-NH₂ to engender a core-shell structure that promotes and achieves a high MTA loading rate through high affinity between MTA and unsaturated Zr site of UiO-66-NH₂. The 5-ALA and 5-carboxyl fluorescein (5-FAM) was successfully loaded and covalently combined with UiO-66-NH₂ due to its high porosity and presence of amino groups. The characterization results indicated that the loading rate of MTA (41.03 wt%) of platform is higher than the reported values. More importantly, the in vitro and in vivo results also demonstrated that it has a good folate targeting ability and realizes high efficient antitumor activity by chemotherapy combied with photodynamic therapy (PDT). This newly developed multifunctional platform could provide a new idea for designing and constructing the carrier with chemotherapy and PDT therapy.

Bio-mineralization of virus-like particles by metal-organic framework nanoparticles enhances the thermostability and immune responses of the vaccines

Virus-like particle (VLPs) vaccines have been extensively studied due to their good immunogenicity and safety; however, they highly rely on cold-chain storage and transportation. Nanotechnology of bio-mineralization as a useful strategy has been employed to improve the thermal stability and immunogenicity of VLPs. A zeolitic imidazole framework (ZIF-8), a core-shell structured nanocomposite, was applied to encapsulate foot-and-mouth disease virus (FMDV) VLPs. It was found that the ZIF-8 shell enhanced the heat resistance of VLPs and promoted their ability to be taken up by cells and escape from lysosomes. The VLPs-ZIF-8 easily activated antigen-presenting cells (APCs), triggered higher secretion levels of cytokines, and elicited stronger immune responses than VLPs alone even after being treated at 37 °C for 7 days. This platform has good potential in the development of VLP-based vaccine products without transportation.

Real-time drug release monitoring from pH-responsive CuS-encapsulated metal-organic frameworks

Real-time monitoring of drug release behaviors over extended periods of time is critical in understanding the dynamics of drug progression for personalized chemotherapeutic treatment. In this work, we report a metal–organic framework (MOF)-based nanotheranostic system encapsulated with photothermal agents (CuS) and therapeutic drug (DOX) to achieve the capabilities of real-time drug release monitoring and combined chemo-photothermal therapy. Meanwhile, folic acid-conjugated polyethylene glycol (FA-PEG) antennas were connected to the MOF through coordination interactions, endowing the MOF with an enhanced active targeting effect toward cancer cells. It is anticipated that such a theranostic agent, simultaneously possessing tumor-targeting, real-time drug monitoring and effective treatment, will potentially enhance the performance in cancer therapy.

A metal–organic framework-based nanotheranostic system was fabricated to achieve the capabilities of tumor-targeting, real-time monitoring of pH-responsive drug release and combined chemo-photothermal therapy.

Recent progress in the applications of gold-based nanoparticles towards tumor-targeted imaging and therapy

Cancer death rate remains high all over the world, scientists are paying increasing attention to meet the requirements for precise diagnosis and therapy. Therefore, early diagnosis and active treatment can effectively improve the five-year survival rate of patients. In recent years, gold-based nanomaterials have received increasing attention in medical fields due to their excellent biocompatibility, low toxicity and unique properties. In addition, because of the inherent nature of gold nanomaterials including for computed tomography (CT), fluorescence/optical imaging (FI/OI), surface enhanced Raman spectroscopy imaging (SERS), photoacoustic imaging (PAI) and photothermal therapy (PTT), various gold nanomaterials were developed as theranostic nanoplatforms. In this review, we summarized the latest developments of nanomaterials in imaging and combined therapy, and the prospects for the future application of gold-based theranostic nanoplatforms were also proposed.

Hierarchical MOF-on-MOF Architecture for pH/GSH-Controlled Drug Delivery and Fe-Based Chemodynamic Therapy

Chemotherapy is still an important and effective clinical treatment for cancer. However, individual drugs hardly achieve precise controlled release and targeted therapy, thus resulting in unavoidable side effects. Fortunately, the emergence of drug carriers is expected to solve the above problems. In this work, the MOF-on-MOF strategy was adopted to encapsulate DOX into double-layer NH2-MIL-88B to fabricate a core-shell-structured DOX@NH2-MIL-88B-On-NH2-MIL-88B (DMM) and then realize the pH and GSH dual-responsive controlled DOX release. Because of the core-shell structure, the drug-loading capacity of DMM reached 14.4 wt %, which was nearly twice that of DOX@NH2-MIL-88B (DM), and the controlled release performance of DMM was also improved at the same time, greatly improving the kinetics equilibrium time of DOX from 2 h (DM) to 16 h (DMM) at pH 5.0. Moreover, we found that DMM also possessed peroxidase-like catalytic activity under acidic conditions, which could catalyze H2O2 to produce •OH, exhibiting the potential chemodynamical treatment of cancer. Cell experiments showed that DMM had a significant inhibitory effect against 4T1 cancer cells, and the survival rate of 4T1 cells was less than 20% at 100 ppm.

Atomically unveiling the structure-activity relationship of biomacromolecule-metal-organic frameworks symbiotic crystal

Crystallization of biomacromolecules-metal-organic frameworks (BMOFs) allows for orderly assemble of symbiotic hybrids with desirable biological and chemical functions in one voxel. The structure-activity relationship of this symbiotic crystal, however, is still blurred. Here, we directly identify the atomic-level structure of BMOFs, using the integrated differential phase contrast-scanning transmission electron microscopy, cryo-electron microscopy and x-ray absorption fine structure techniques. We discover an obvious difference in the nanoarchitecture of BMOFs under different crystallization pathways that was previously not seen. In addition, we find the nanoarchitecture significantly affects the bioactivity of the BMOFs. This work gives an important insight into the structure-activity relationship of BMOFs synthesized in different scenarios, and may act as a guide to engineer next-generation materials with excellent biological and chemical functions.

Biomolecule-metal-organic-frameworks allow for the creation of hybrid materials with desired biological and chemical function. Here, the authors refine the structure-function relationship by identifying the atomic-layer structure of the hybrids and show differences in structure upon different crystallisation pathways.

Spray drying-assisted construction of hierarchically porous ZIF-8 for controlled release of doxorubicin

The intrinsic properties and structure of carrier materials, as well as the drug-loading method, are crucial to the fabrication of high-performance controlled drug release systems. Metal-organic frameworks (MOFs) have attracted great attention in drug delivery due to their rich variety and very precisely designable structures, but their inherent small pores limit their application towards large-size drug molecules. Herein, we report a facile and efficient approach for the construction of hierarchically porous ZIF-8 (HP-ZIF-8) by spray drying. The homogeneously distributed mesopores, which result from the interspaces in the closely arranged nanosized ZIF-8 (N-ZIF-8), can be tuned by adjusting the primary particle size. More importantly, a drug (doxorubicin (DOX), for example) can be simultaneously encapsulated during the fabrication process of HP-ZIF-8, achieving a high loading rate of 79% and an encapsulation efficiency of 79%. Furthermore, we demonstrate that the obtained DOX@HP-ZIF-8 is a pH-responsive system and the release can also be controlled by the mesopore size. Although HP-ZIF-8 shows obvious advantages in drug loading and release performance compared with N-ZIF-8 loaded with DOX by the same solvent adsorption approach, DOX@HP-ZIF-8 displays significantly increased loading capacity (more than 3 times) and the slowest release rate due to its drug-loading method. Their therapeutic efficacy on HeLa cells has also been proved. These findings have important implications for the construction of HP-MOFs as drug carriers and will also present a new platform for controlled drug release and biomedical applications.

A tumor microenvironment-responsive Co/ZIF-8/ICG/Pt nanoplatform for chemodynamic and enhanced photodynamic antitumor therapy

Hypoxia and the overexpression of hydrogen peroxide (H2O2) in the tumor microenvironment (TME) are conducive to cancer cell proliferation, which greatly hinders cancer treatment. Here, we design a novel TME-responsive therapeutic nanoplatform Co/ZIF-8/ICG/Pt (CZIP) to achieve chemodynamic therapy (CDT) and enhanced photodynamic therapy (PDT). In this nanoplatform, under near-infrared light (NIR) irradiation, the photosensitizer indocyanine green (ICG) can generate singlet oxygen (1O2) for cancer cell apoptosis. Meanwhile, overexpressed H2O2 in the TME could be catalyzed to generate O2 by the loaded Pt to relieve tumor hypoxia and promote the PDT-induced 1O2 production. In addition, the doped Co2+ could react with H2O2 to produce hydroxyl radicals (˙OH) for CDT. The multifunctional nanoplatform CZIP showed high biosafety and a good antitumor effect, which would provide a new route for cancer therapy.

Nine days extended release of adenosine from biocompatible MOFs under biologically relevant conditions

Adenosine is a small molecule directly involved in maintaining homeostasis under pathological and stressful conditions. Due to its rapid metabolism, delivery vehicles capable of exhibiting extended release of adenosine are of paramount interest. Herein, we demonstrate a superior long-term (9 days) release profile of adenosine from biocompatible MOFs in a physiologically relevant environment. The key to the biocompatibility of MOFs is their stability under biologically relevant conditions. This study additionally highlights the interplay between the chemical stability of prototypal MOFs, assessed under physiological conditions, and their cytotoxicity profiles. Cytotoxicity of the prototypal Zn-based MOF (ZIF-8) and three Zr-based MOFs (UiO-66, UiO-66-NH₂, and MOF-801) on six cell types was assessed. The cell types selected were valve interstitial cells (VICs), valve endothelial cells (VECs), adipose tissue-derived stem cells (ADSCs), and cell lines U937, THP1, and HeLa. Zr-based MOFs demonstrated a wide tolerance range in the cell culture cytotoxicity assays, demonstrating cell viability up to a very high dose of ∼1000 μg mL^-1, as compared to ZIF-8 which showed notable cytotoxicity in as little as ∼100 μg mL^-1 dose. This study demonstrates, for the first time, the utilization of biocompatible MOFs for adenosine delivery as well as establishes a direct link between structural instability in the cell culture medium and the observed cytotoxicity of the studied MOFs.

Stimuli-Responsive Nanoparticles for Controlled Drug Delivery in Synergistic Cancer Immunotherapy

Cancer immunotherapy has achieved promising clinical progress over the recent years for its potential to treat metastatic tumors and inhibit their recurrences effectively. However, low patient response rates and dose-limiting toxicity remain as major dilemmas for immunotherapy. Stimuli-responsive nanoparticles (srNPs) combined with immunotherapy offer the possibility to amplify anti-tumor immune responses, where the weak acidity, high concentration of glutathione, overexpressions of enzymes, and reactive oxygen species, and external stimuli in tumors act as triggers for controlled drug release. This review highlights the design of srNPs based on tumor microenvironment and/or external stimuli to combine with different anti-tumor drugs, especially the immunoregulatory agents, which eventually realize synergistic immunotherapy of malignant primary or metastatic tumors and acquire a long-term immune memory to prevent tumor recurrence. The authors hope that this review can provide theoretical guidance for the construction and clinical transformation of smart srNPs for controlled drug delivery in synergistic cancer immunotherapy.

Dual antisense oligonucleotide targeting miR-21/miR-155 synergize photodynamic therapy to treat triple-negative breast cancer and inhibit metastasis

Triple negative breast cancer (TNBC) is a greatly aggressive subtype of breast cancer with high recurrence and mortality rates. Chemotherapy as a primary treatment for cancer is limited due to toxic side effects and drug resistance. Therefore, low toxicity and more effective breast cancer therapeutic approaches are greatly desired. In this study, a strategy which using ZIF-90 nanoparticles co-deliver Ce6-anti-miR-21 and Ce6-anti-miR-155 into the tumor cells was developed. Due to the pH responsive drug release of ZIF-90, antisense oligonucleotides (anti-miRNAs) and photosensitizers are able to be efficiently released inside tumor microenvironment. The nano delivery system captures overexpressed oncogenic miRNAs while the photosensitizer Ce6 generates ROS under light irradiation to effectively induce the apoptosis of tumor cell. This combinatorial effect was verified by results showing that the purposed therapic method could effectively inhibit tumor cell proliferation and metastasis. The concept of antisense oligonucleotide combined with photodynamic therapy has great potential in cancer treatment or adjuvant therapy.

Hydrogen Sulfide: An Emerging Precision Strategy for Gas Therapy

Advances in nanotechnology have enabled the rapid development of stimuli-responsive therapeutic nanomaterials for precision gas therapy. Hydrogen sulfide (H₂ S) is a significant gaseous signaling molecule with intrinsic biochemical properties, which exerts its various physiological effects under both normal and pathological conditions. Various nanomaterials with H₂ S-responsive properties, as new-generation therapeutic agents, are explored to guide therapeutic behaviors in biological milieu. The cross disciplinary of H₂ S is an emerging scientific hotspot that studies the chemical properties, biological mechanisms, and therapeutic effects of H₂ S. This review summarizes the state-of-art research on H₂ S-related nanomedicines. In particular, recent advances in H₂ S therapeutics for cancer, such as H₂ S-mediated gas therapy and H₂ S-related synergistic therapies (combined with chemotherapy, photodynamic therapy, photothermal therapy, and chemodynamic therapy) are highlighted. Versatile imaging techniques for real-time monitoring H₂ S during biological diagnosis are reviewed. Finally, the biosafety issues, current challenges, and potential possibilities in the evolution of H₂ S-based therapy that facilitate clinical translation to patients are discussed.

Nanoscale Metal−Organic Frameworks and Their Nanomedicine Applications

Abundant connectivity among organic ligands and inorganic metal ions makes the physical and chemical characters of metal-organic frameworks (MOFs) could be precisely devised and modulated for specific applications. Especially nanoscale MOFs (NMOFs), a unique family of hybrid nanomaterials, with merits of holding the nature as the mainstay MOFs and demonstrating particle size in nanoscale range which enable them prospect platform in clinic. Adjustability of composition and structure allows NMOFs with different constituents, shapes, and characteristics. Oriented frameworks and highly porous provide enough space for packing therapeutic cargoes and various imaging agents efficiently. Moreover, the relatively labile metal-ligand bonds make NMOFs biodegradable in nature. So far, as a significant class of biomedically relevant nanomaterials, NMOFs have been explored as drug carriers, therapeutic preparation, and biosensing and imaging preparation owing to their high porosity, multifunctionality, and biocompatibility. This review provides up-to-date developments of NMOFs in biomedical applications with emphasis on size control, synthetic approaches, and surfaces functionalization as well as stability, degradation, and toxicity. The outlooks and several crucial issues of this area are also discussed, with the expectation that it may help arouse widespread attention on exploring NMOFs in potential clinical applications.

Encapsulation, Release, and Cytotoxicity of Doxorubicin Loaded in Liposomes, Micelles, and Metal-Organic Frameworks: A Review

Doxorubicin (DOX) is one of the most widely used anthracycline anticancer drugs due to its high efficacy and evident antitumoral activity on several cancer types. However, its effective utilization is hindered by the adverse side effects associated with its administration, the detriment to the patients’ quality of life, and general toxicity to healthy fast-dividing cells. Thus, delivering DOX to the tumor site encapsulated inside nanocarrier-based systems is an area of research that has garnered colossal interest in targeted medicine. Nanoparticles can be used as vehicles for the localized delivery and release of DOX, decreasing the effects on neighboring healthy cells and providing more control over the drug’s release and distribution. This review presents an overview of DOX-based nanocarrier delivery systems, covering loading methods, release rate, and the cytotoxicity of liposomal, micellar, and metal organic frameworks (MOFs) platforms.

Augmented EPR effect post IRFA to enhance the therapeutic efficacy of arsenic loaded ZIF-8 nanoparticles on residual HCC progression

BACKGROUND

Insufficient radiofrequency ablation (IRFA) can promote the local recurrence and distal metastasis of residual hepatocellular carcinoma (HCC), which makes clinical treatment extremely challenging. In this study, the malignant transition of residual tumors after IRFA was explored. Then, arsenic-loaded zeolitic imidazolate framework-8 nanoparticles (As@ZIF-8 NPs) were constructed, and their therapeutic effect on residual tumors was studied.

RESULTS

Our data showed that IRFA can dramatically promote the proliferation, induce the metastasis, activate the epithelial-mesenchymal transition (EMT) and accelerate the angiogenesis of residual tumors. Interestingly, we found, for the first time, that extensive angiogenesis after IRFA can augment the enhanced permeability and retention (EPR) effect and enhance the enrichment of ZIF-8 nanocarriers in residual tumors. Encouraged by this unique finding, we successfully prepared As@ZIF-8 NPs with good biocompatibility and confirmed that they were more effective than free arsenic trioxide (ATO) in sublethal heat-induced cell proliferation suppression, apoptosis induction, cell migration and invasion inhibition, and EMT reversal in vitro. Furthermore, compared with free ATO, As@ZIF-8 NPs exhibited remarkably increased therapeutic effects by repressing residual tumor growth and metastasis in vivo.

CONCLUSIONS

This work provides a new paradigm for the treatment of residual HCC after IRFA.

Multifunctional Anthracene-Based Ni-MOF with Encapsulated Fullerenes: Polarized Fluorescence Emission and Selective Separation of C70 from C60

We report an anthracene-based Ni-MOF [Ni(II) metal-organic framework, {[Ni(μ₂-L)₂Cl₂]·x(C₆H₆)·y(MeOH)}_n (1), L = anthracene-9,10-diylbis(methylene)diisonicotinate] whose crystal structure reveals the presence of hexagonal channels with a pore size of 1.4 nm that can accommodate guests such as C₆₀ and C₇₀. Both confocal fluorescence and Raman microscopy results are in agreement with a homogeneous distribution of fullerenes throughout the single crystals of 1. Efficient energy transfer from 1 to the fullerenes was observed, which emitted partially polarized fluorescence emission. Stronger binding between 1 and C₇₀ versus C₆₀ was confirmed from HPLC analysis of the dissolved material and provides a basis for the selective retention of C₇₀ in liquid chromatography columns packed with 1.

Inhibition of the urea-urease reaction by the components of the zeolite imidazole frameworks-8 and the formation of urease-zinc-imidazole hybrid compound

In the past decade, much effort has been devoted to using chemical clock-type reactions in material design and driving the self-assembly of various building blocks. Urea-urease enzymatic reaction has chemical pH clock behavior in an unbuffered medium, in which the induction time and the final pH can be programmed by the concentrations of the reagents. The urea-urease reaction can offer a new alternative in material synthesis, where the pH and its course in time are crucial factors in the synthesis. However, before using it in any synthesis method, it is important to investigate the possible effects of the reagents on the enzymatic reaction. Here we investigate the effect of the reagents of the zeolite imidazole framework-8 (zinc ions and 2-methylimidazole) on the urea-urease reaction. We have chosen the zeolite imidazole framework-8 because its formation serves as a model reaction for the formation of other metal–organic frameworks. We found that, besides the inhibition effect of the zinc ions which is well-known in the literature, 2-methylimidazole inhibits the enzymatic reaction as well. In addition to the observed inhibition effect, we report the formation of a hybrid urease-zinc-2-methylimidazole hybrid material. To support the inhibition effect, we developed a kinetic model which reproduced qualitatively the experimentally observed kinetic curves.

Synthesis of zeolitic imidazolate framework-8 and gold nanoparticles in a sustained out-of-equilibrium state

The design and synthesis of crystalline materials are challenging due to the proper control over the size and polydispersity of the samples, which determine their physical and chemical properties and thus applicability. Metal − organic frameworks (MOFs) are promising materials in many applications due to their unique structure. MOFs have been predominantly synthesized by bulk methods, where the concentration of the reagents gradually decreased, which affected the further nucleation and crystal growth. Here we show an out-of-equilibrium method for the generation of zeolitic imidazolate framework-8 (ZIF-8) crystals, where the non-equilibrium crystal growth is maintained by a continuous two-side feed of the reagents in a hydrogel matrix. The size and the polydispersity of the crystals are controlled by the fixed and antagonistic constant mass fluxes of the reagents and by the reaction time. We also present that our approach can be extended to synthesize gold nanoparticles in a redox process.

ZIF-8@GMP-Tb nanocomplex for ratiometric fluorescent detection of alkaline phosphatase activity

Luminescent metal-organic frameworks (LMOFs) and their functional materials with unique characteristics can provide the basis for the construction of new analytical techniques, which can meet the continuous demand for various fields. In this work, guanosine monophosphate (GMP), terbium ion (Tb³⁺) and zeolitic imidazolate framework-8 (ZIF-8) are self-assembled to form a ZIF-8@GMP-Tb nanocomplex, which can be utilized as a ratiometric fluorescent probe to monitor alkaline phosphatase (ALP) activity. Specifically, with adding ALP, the fluorescence intensity at 547 nm (one of the characteristic emission peaks of Tb³⁺) obviously decreased. Meanwhile, the conjugated structure of GMP increased the fluorescence of ZIF-8 (located at 330 nm). The possible mechanism was proposed through the characterization of the materials. Based on the variation of the emission peaks at 330 and 547 nm, the ratiometric fluorescent sensor of ALP has a linear range of 0.25-20 U/L. Moreover, applying this sensing system to the detection of ALP in the human serum sample and ALP inhibitor investigation possesses satisfactory results. This work provides a new perspective for the utilization of ZIF-8 and lanthanide ions in manufacturing simple and sensitive sensors.

Pore engineering of biomolecule-based metal–organic framework nanocarriers for improving loading and release of paclitaxel

There has been growing interest in employing metal–organic frameworks (MOFs) incorporated with biomolecules, known as b-MOFs, in biomedical applications.

In situ synthesis of a functional ZIF-8 nanocomposite for synergistic photodynamic–chemotherapy and pH and NIR-stimulated drug release

UCNP/TiO2/Cur@ZIF-8 can be used as a NIR and pH-responsive photodynamic-chemo candidate for tumor therapy.

Metal-Organic-Framework-Based Hydrogen-Release Platform for Multieffective Helicobacter Pylori Targeting Therapy and Intestinal Flora Protective Capabilities

Helicobacter pylori (H. pylori) infection is the leading cause of chronic gastritis, peptic ulcer, and gastric cancer. Antibiotics, as traditional method for eliminating H. pylori, have no targeting effect, which causes serious bacterial resistance and gut dysbacteriosis. Moreover, antibiotics can hardly address hyperactive inflammatory response or damaged gastric mucosal barrier caused by H. pylori infection. Here, a pH-responsive metal-organic framework hydrogen-generation nanoparticle (Pd(H) @ ZIF-8) is reported, which is encapsulated with ascorbate palmitate (AP) hydrogel. Both in vitro and in vivo experiments demonstrate that the outer AP hydrogel can target and adhere to the inflammatory site through electrostatic interactions, and is then hydrolyzed by matrix metalloproteinase (MMP) enriching in inflammatory sites. The released Pd(H) @ ZIF-8 nanoparticles are further decomposed by gastric acid to generate zinc ions (Zn²⁺ ) and hydrogen, thus effectively killing H. pylori, alleviating inflammation and restoring impaired gastric mucosa simultaneously. Unexpectedly, this metal-organic framework hydrogen-generation platform (Pd(H) @ ZIF-8 @ AP) also has an effect toward avoiding the imbalance of intestinal flora, which thus provides a more precise, effective, and healthy strategy for the treatment of H. pylori infection.

Targeted therapy of atherosclerosis by zeolitic imidazolate framework-8 nanoparticles loaded with losartan potassium via simultaneous lipid-scavenging and anti-inflammation

Atherosclerosis (AS) is a condition associated with dysfunctional lipid metabolism and an inflammatory immune microenvironment that remains the leading cause of severe cardiovascular events. Drugs exhibiting both anti-inflammatory and lipid-scavenging...

The Impact of MOF in pH-dependent Drug Delivery System: Progress in Last Decade

Metal-organic frameworks (MOFs) are porous crystalline materials of one-, two-, or three-dimensional networks manufactured from metal ions/clusters and multidentate organic linkers through coordination bonding. MOFs are one of the most...