Nanoscale Metal-organic Frameworks Research Articles

Bifunctional Metal–Organic Framework Synergistically Enhances Radiotherapy and Activates STING for Potent Cancer Radio‐Immunotherapy

AbstractThe activation of the stimulator of interferon genes (STING) protein by cyclic dinucleotide metabolites plays a critical role in antitumor immunity. However, synthetic STING agonists like 4‐(5,6‐dimethoxybenzo[b]thiophen‐2‐yl)‐4‐oxobutanoic acid (MSA‐2) exhibit suboptimal pharmacokinetics and fail to sustain STING activation in tumors for effective antitumor responses. Here, we report the design of MOF/MSA‐2, a bifunctional MSA‐2 conjugated nanoscale metal–organic framework (MOF) based on Hf6 secondary building units (SBUs) and hexakis(4′‐carboxy[1,1′‐biphenyl]‐4‐yl)benzene bridging ligands, for potent cancer radio‐immunotherapy. By leveraging the high‐Z properties of the Hf6 SBUs, the MOF enhances the therapeutic effect of X‐ray radiation and elicits potent immune stimulation in the tumor microenvironment. MOF/MSA‐2 further enhances radiotherapeutic effects of X‐rays by enabling sustained STING activation and promoting the infiltration and activation of immune cells in the tumors. MOF/MSA‐2 plus low‐dose X‐ray irradiation elicits strong STING activation and potent tumor regression, and when combined with an immune checkpoint inhibitor, effectively suppresses both primary and distant tumors through systemic immune activation.

Perturbation of Enzyme Structure by nano-Metal Organic Frameworks: A Question Mark on their Safety-by-Design?

Our study investigates the interactions between nanoscale Metal-Organic Frameworks (nMOFs), specifically ZIF-8 and CuIm, and key enzymes: Acetylcholine Esterase (AChE), α-amylase. Using circular dichroism (CD) spectroscopy, we observed significant alterations in the secondary structures of these enzymes upon interaction with nMOFs. AChE showed a reduction in α-helix content from 20.1% to a significantly lower value when exposed to 160µg/mL of nMOFs, with a corresponding increase in β-sheet and other structural components. Enzymatic activity assays revealed that CuIm nMOFs decreased AChE activity by 67.08% at the highest concentration tested (160µg/mL). ZIF-8 also affected AChE activity significantly at this concentration. Similarly, α-amylase exhibited structural changes, with increasing concentrations of nMOFs leading to a near-total loss of secondary structure at 80 and 160µg/mL. These structural changes were accompanied by a marked decrease in enzymatic activity, particularly with CuIm nMOFs showing the most substantial inhibitory effects. Our findings highlight the profound impact of nMOFs on enzyme structure and function, emphasising the need for comprehensive assessments of nMOFs' potential toxicity and understanding the aspects of their safety-by-design.

PH-activated metal–organic layer nanozyme for ferroptosis tumor therapy

Nanozymes have made great achievements in the research of tumor therapy. However, due to the complex tumor microenvironment, the catalytic activity and biosafety of nanozymes are limited. High catalytic efficiency is a relentless pursuit for the preparation of high-performance nanozymes. Dimensional reduction from 3D nanoscale metal–organic frameworks (nMOFs) to 2D nanoscale metal–organic layers (nMOLs) increases the encounters frequency of nanozymes and substrate, which facilitates the diffusion of reactive oxygen species (ROS) from nMOLs, thus significantly improving the effectiveness of chemodynamic therapy. In this study, He@Ce-BTC nMOF and He@Ce-BTB nMOL based on Ce6 SBUs were synthesized by solvothermal reaction. Compared with the 3D nMOFs, the 2D nanozymes He@Ce-BTB nMOL possessed enhanced ROS catalytic efficiency, were able to be activated by the tumor acidic microenvironment with the polymerase mimetic activities (CAT, POD, GSH-OXD) that enhances the lipid peroxidation process and accelerates the process of ferroptosis thereby killing tumor cells. In addition, He@Ce-BTB does not affect normal tissue cells, thus avoiding diffusion-induced side effects. He@Ce-BTB has shown excellent therapeutic effects in vitro and in vivo, which indicates its potential for clinical application, and is expected to become a new generation of drugs for the treatment of tumors.

Hyaluronic acid-functionalized MOFs for combined sunitinib and siRNA therapy in renal cell carcinoma

Sunitinib is a first-line treatment for renal cell carcinoma (RCC), but suffers from drug resistance, causing therapy failure. Therefore, nano-scale delivery systems should be introduced for targeted delivery. Metal-organic frameworks (MOFs) are attractive drug carriers that not only enable multidrug combination therapies but also exert photodynamic effects by incorporating photosensitizers as components. Here, a Zr-based porphyrinic nanoscale MOF, PCN224, was prepared as the carrier for the co-delivery of sunitinib and the siRNA against vascular endothelial growth factor receptor-2 (VEGFR-2). Drug-loaded PCN-224 is coated with hyaluronic acid (HA) to prevent drug molecular leakage and to exert tumor-targeting effects (CD44 in tumor cells). Photodynamic therapy was conducted under 660 nm laser (50 mW·cm−2, 10 min) irradiation. Compared with St/siVEGFR-2@PCN-224@HA without the HA coating, St/siVEGFR-2@PCN-224@HA significantly suppressed cell viability and promoted cell apoptosis. Laser irradiation further increased the anti-cancer effect of St/siVEGFR-2@PCN-224@HA by generating cytotoxic ROS. H&E staining of major organs revealed no signs of damage, indicating the biosafety of St/siVEGFR-2@PCN-224@HA. The prepared St/siVEGFR-2@PCN-224@HA system enables triple inhibition of tumor growth via a combination of targeted therapy and genetic and photodynamic therapy to enhance the therapeutic effects on RCC.

Porphyrin-engineered nanoscale metal-organic frameworks: enhancing photodynamic therapy and ferroptosis in oncology.

Photodynamic therapy and ferroptosis induction have risen as vanguard oncological interventions, distinguished by their precision and ability to target vulnerabilities in cancer cells. Photodynamic therapy's non-invasive profile and selective cytotoxicity complement ferroptosis' unique mode of action, which exploits iron-dependent lipid peroxidation, offering a pathway to overcome chemoresistance with lower systemic impact. The synergism between photodynamic therapy and ferroptosis is underscored by the depletion of glutathione and glutathione peroxidase four inhibitions by photodynamic therapy-induced reactive oxygen species, amplifying lipid peroxidation and enhancing ferroptotic cell death. This synergy presents an opportunity to refine cancer treatment by modulating redox homeostasis. Porphyrin-based nanoscale metal-organic frameworks have unique hybrid structures and exceptional properties. These frameworks can serve as a platform for integrating photodynamic therapy and ferroptosis through carefully designed structures and functions. These nanostructures can be engineered to deliver multiple therapeutic modalities simultaneously, marking a pivotal advance in multimodal cancer therapy. This review synthesizes recent progress in porphyrin-modified nanoscale metal-organic frameworks for combined photodynamic therapy and ferroptosis, delineating the mechanisms that underlie their synergistic effects in a multimodal context. It underscores the potential of porphyrin-based nanoscale metal-organic frameworks as advanced nanocarriers in oncology, propelling the field toward more efficacious and tailored cancer treatments.

Characterization of the effects of bridging linker on the β-Lactoglobulin binding mechanism on the nanoscale metal-organic frameworks

Revealing the interaction modes between nanoscale metal-organic frameworks (NMOFs) and food matrix is crucial for functional release but it still remains largely unknown to date. This study specifically focused on the milk protein adsorption mechanism of NMOFs using UiO66/UiO66-NH2 and β-lactoglobulin (β-LG) as models. UiO66 and UiO66-NH2 quenched the fluorescence of β-LG via static mechanism. Due to the enhanced electrostatic forces caused by NH2, UiO66-NH2–β-LG (2.83 × 105 mol·L−1) exhibited higher binding constant than UiO66-β-LG (2.61 × 105 mol·L−1), while UiO66 with higher hydrophobicity adsorbed more β-LG. The defects of UiO influenced the binding sites on the β-LG, and the higher the defect degree, the higher the binding energy. For the stability of the system, the H-bonding between UiO66 and SER30/PRO38, and the hydrophobic interaction between UiO66-NH2 and LYS101 played important roles. Furthermore, the secondary structure content of β-LG changed after interacting with both UiO, resulting in reduced density of β-LG.

Bifunctional Metal-Organic Framework Synergistically Enhances Radiotherapy and Activates STING for Potent Cancer Radio-Immunotherapy.

The activation of the stimulator of interferon genes (STING) protein by cyclic dinucleotide metabolites plays a critical role in antitumor immunity. However, synthetic STING agonists like 4-(5,6-dimethoxybenzo[b]thiophen-2-yl)-4-oxobutanoic acid (MSA-2) exhibit suboptimal pharmacokinetics and fail to sustain STING activation in tumors for effective antitumor responses. Here, we report the design of MOF/MSA-2, a bifunctional MSA-2 conjugated nanoscale metal-organic framework (MOF) based on Hf6 secondary building units (SBUs) and hexakis(4'-carboxy[1,1'-biphenyl]-4-yl)benzene bridging ligands, for potent cancer radio-immunotherapy. By leveraging the high-Z properties of the Hf6 SBUs, the MOF enhances the therapeutic effect of X-ray radiation and elicits potent immune stimulation in the tumor microenvironment. MOF/MSA-2 further enhances radiotherapeutic effects of X-rays by enabling sustained STING activation and promoting the infiltration and activation of immune cells in the tumors. MOF/MSA-2 plus low-dose X-ray irradiation elicits strong STING activation and potent tumor regression, and when combined with an immune checkpoint inhibitor, effectively suppresses both primary and distant tumors through systemic immune activation.

Excessive autophagy-inducing and highly penetrable biomineralized bacteria for multimodal imaging-guided and mild hyperthermia-enhanced immunogenic cell death

The tumor microenvironment, characterized by hypoxia, supports the efficacy of anaerobic bacteria like attenuated S. typhimurium in cancer therapies. These bacteria target and penetrate deep tumor regions, significantly reducing tumor size but often lead to tumor regrowth due to limited long-term efficacy. To enhance the therapeutic impact, a novel biohybrid system, S@UIL, has been developed by coating S. typhimurium with a zirconium-based nanoscale metal–organic framework (UiO-66-NH2) loaded with indocyanine green (ICG) and luteolin (LUT). This system maintains the bacteria’s tumor-targeting ability while increasing the penetration and therapeutic effectiveness through excessive autophagy and mild hyperthermia. In a subcutaneous colon cancer model, the integration of LUT and ICG promotes autophagic cell death and photothermal sensitization, leading to the release of damage-associated molecular patterns (DAMPs). These DAMPs activate immune responses through dendritic cells and T-cells, enhancing immunogenic cell death (ICD) and potentially reducing immune evasion by tumors. This single-administration approach also integrates multimodal imaging capabilities, providing a promising strategy for improved tumor ICD induction and cancer progression inhibition.

Abstract C027: Nanoscale-metal organic frameworks as drug delivery vehicles for novel hepatocellular carcinoma therapy

Abstract Metal-organic frameworks (MOFs) are porous crystalline materials composed of organic linkers connected by metal clusters. Recently, MOFs have garnered significant interest in biomedical applications due to their high porosity and ability to be tailored to accommodate various guest molecules. Their use as drug delivery vehicles in cancer treatment has been extensively explored as an alternative to traditional chemotherapy, aiming to enhance efficacy and reduce harmful side effects. Beyond serving as carriers, MOFs can be functionalized with moieties that selectively bind to cancer cells, enabling advanced targeting capabilities. This presentation examines current research on using Zr-based MOF, UiO-66 as a drug delivery vehicle for novel small molecule inhibitor PDZ1i in combinatorial therapies for hepatocellular cancer. PDZ1i targets MDA-9, a pro-metastatic and pro-angiogenic gene associated with various cancers. Citation Format: Karl T. Jackson. Nanoscale-metal organic frameworks as drug delivery vehicles for novel hepatocellular carcinoma therapy [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C027.

Digitonin-Loaded Nanoscale Metal-Organic Framework for Mitochondria-Targeted Radiotherapy-Radiodynamic Therapy and Disulfidptosis.

The efficacy of radiotherapy (RT) is limited by inefficient X-ray absorption and reactive oxygen species generation, upregulation of immunosuppressive factors, and a reducing tumor microenvironment (TME). Here, the design of a mitochondria-targeted and digitonin (Dig)-loaded nanoscale metal-organic framework, Th-Ir-DBB/Dig, is reported to overcome these limitations and elicit strong antitumor effects upon low-dose X-ray irradiation. Built from Th6O4(OH)4 secondary building units (SBUs) and photosensitizing Ir(DBB)(ppy)2 2+ (Ir-DBB, DBB=4,4'-di(4-benzoato)-2,2'-bipyridine; ppy=2-phenylpyridine) ligands, Th-Ir-DBB exhibits strong RT-radiodynamic therapy (RDT) effects via potent radiosensitization with high-Z SBUs for hydroxyl radical generation and efficient excitation of Ir-DBB ligands for singlet oxygen production. Th-Ir-DBB/Dig releases digitonin in acidic TMEs to trigger disulfidptosis of cancer cells and sensitize cancer cells to RT-RDT through glucose and glutathione depletion. The released digitonin simultaneously downregulates multiple immune checkpoints in cancer cells and T cells through cholesterol depletion. As a result, Th-Ir-DBB/dig plus X-ray irradiation induces strong antitumor immunity to effectively inhibit tumor growth in mouse models of colon and breast cancer.

Recovering skin-nerve interaction by nanoscale metal-organic framework for diabetic ulcers healing

Skin-nerve interaction plays an important role in promoting wound healing. However, in diabetic ulcers (DUs), the diabetic periphery neuropathy and excessive levels of reactive oxygen species (ROS) block skin-nerve interaction and further impede the DUs healing. Herein, we developed a nanoscale metal-organic framework loaded with nerve growth factor (NGF/Ce-UiO-66, denoted NGF/CU) for the treatment of DUs. The Ce-UiO-66 (CU) was applied as an antioxidant to scavenge ROS and reduce the inflammatory response while the NGF aided in the recovery of cutaneous nerves to further promote DUs healing. Both in vitro and in vivo experiments revealed the effective ability of NGF/CU for DUs healing. Subsequent RNA sequencing analysis revealed the mechanism that NGF/CU can improve wound healing by inhibiting the NF-κB signaling pathway and recovering the neuroendocrine system of the skin. This strategy of nerve regulation will provide more ideas for the treatment of DUs and other organ injuries.

Boosting Ferroptosis and immunotherapy for Colorectal Cancer by Lactate‐Related Metabolic Reprogramming

AbstractAs the presence of anaerobic metabolism of glucose, solid tumors characteristically display higher levels of lactate production, which attenuate ferroptosis therapy and the subsequent anti‐tumor immune response. Herein, hyaluronic acid (HA)‐modified and lactate oxidase (LOX)‐loaded nanoscale metal organic frameworks (MOFs), termed as FCS@LOX@HA (FCSLH) is constructed, achieving tumor‐targeted metabolic combined chemo‐dynamic therapy (CDT). Notably, the high LOX‐loading capacity of MOFs is achieved by adjusting the Fe/Cu ratio. Upon internalization by cancer cells, the FCS MOFs reacted with local glutathione (GSH) to release Fe/Cu ions for CDT. Meanwhile, the LOX catalyzed endogenous lactate to pyruvate accompanied with a release of H2O2; while the latter can enhance the FCS MOFs‐mediated CDT effect. Additionally, lactate exhaustion can impair the antioxidant system by inhibiting the HIF‐1α/SLC1A1 pathway, resulting in the accumulation of lipid peroxidation, and ferroptosis occurs accompanied by immunogenic cell death. Furthermore, lactate exhaustion within tumor‐associated macrophages (TAMs) can inhibit M2 macrophage polarization by suppressing the NF‐κB/HIF‐1α pathway, thereby augmenting anti‐tumor immune response. The in vivo studies demonstrated that cooperating with PD‐L1 antibodies can achieve excellent anti‐tumor therapeutic efficacy. Taken together, FCSLH can amplify the ferroptosis‐mediated immune response through simultaneous dysfunction of cancer cells and TAMs, which provides novel insight for integrating metabolic programmed therapy and immunotherapy.

Impact of photoaging on the chemical and cytotoxic properties of nanoscale zeolitic imidazolate framework-8

This study investigated the influence of photoaging on a nanoscale metal-organic framework (MOF), truncated rhombic dodecahedron nano-zeolitic imidazolate framework-8 (nZIF-8), focusing on its oxidative stress, inflammation, and implications for pulmonary diseases. We observed significant photodegradation-induced transformations in nZIF-8, characterized by a reduction in particle size from 200.5 to 101.4 nm and notable structural disintegration after prolonged exposure to simulated solar radiation. This alteration resulted in a marked decrease in oxidative cytotoxicity in BEAS-2B cells, which was attributed to changes in surface properties and reduced reactive oxygen species (ROS) production. Gene expression analysis further revealed a decrease in cytotoxic and inflammatory responses, which potentially lowers the risk of chronic obstructive pulmonary disease (COPD). Aged nZIF-8 also showed diminished capacity to induce pro-inflammatory cytokines and influence COPD-related gene expression, reducing its potential to exacerbate COPD pathogenesis. Our findings highlight the critical need for comprehensive safety evaluations of these materials, while considering their long-term environmental and biological impacts. The diminished cytotoxicity and inflammatory potential of aged nZIF-8 highlighted its enhanced suitability for broader applications, indicating that photoaging may lead to safer and more sustainable material utilization.

Targeted biocompatible Zn-metal–organic framework nanocomposites for intelligent chemotherapy of breast cancer cells

Finding a novel drug delivery system (DDS) represents one of the most challenging endeavors in cancer therapy. Hence, in this study, we developed a new biocompatible and biodegradable zinc-based nanoscale metal–organic framework (Zn-NMOF) coated with folic acid (FA) functionalized chitosan (CS) to facilitate targeted delivery of doxorubicin (D), a standard chemotherapeutic agent, into breast cancer cells. The synthesis of the NMOF-CS-FA-D nanocomposite preceded its comprehensive characterization via FT-IR, DLS, XRD, SEM, and TEM analyses. Subsequent in vitro studies were conducted on MCF-7 breast cancer cells and HFF-1 normal cells, encompassing assessments of cell viability, expression levels of apoptotic and autophagy genes, cell cycle arrest, and apoptotic analyses. The size of the NMOF-CS-FA-D particles was determined to be less than 80 nm, with a drug loading efficiency of 72 ± 5%. The release kinetics of DOX from the nanocomposite were investigated, revealing controlled release behavior at pH 7.4 and accelerated release at pH 5.0, which is conducive to drug delivery into cancer cells. In vitro results indicated a 17.39% ± 6.34 cell viability after 24 h of treatment with a 40 nM concentration of the NMOF-CS-FA-D nanocomposite. Furthermore, the expression levels of Caspase-9 and BAX, key apoptotic genes, along with BECLIN1, an autophagy gene, were found to increase by two-fold, four-fold, and two-fold, respectively, following 5 h of treatment with the nanocomposite. Additionally, analysis of cell cycle distribution revealed 15.4 ± 2% of cells in the sub-G1 phase, indicative of apoptotic cells, and 31.9% of cells undergoing early and late apoptosis in MCF-7 cells. Collectively, these findings underscore the potential of the NMOF-CS-FA-D nanocomposite in inhibiting cancer cell proliferation with low side effects.

Tumor-targeted delivery of hyaluronic acid/polydopamine-coated Fe2+-doped nano-scaled metal–organic frameworks with doxorubicin payload for glutathione depletion-amplified chemodynamic-chemo cancer therapy

Chemodynamic therapy (CDT), an emerging cancer treatment modality, uses multivalent metal elements to convert endogenous hydrogen peroxide (H2O2) to toxic hydroxyl radicals (•OH) via a Fenton or Fenton-like reaction, thus eliciting oxidative damage of cancer cells. However, the antitumor potency of CDT is largely limited by the high glutathione (GSH) concentration and low catalytic efficiency in the tumor sites. The combination of CDT with chemotherapy provides a promising strategy to overcome these limitations. In this work, to enhance antitumor potency by tumor-targeted and GSH depletion-amplified chemodynamic-chemo therapy, the hyaluronic acid (HA)/polydopamine (PDA)-decorated Fe2+-doped ZIF-8 nano-scaled metal–organic frameworks (FZ NMs) were fabricated and utilized to load doxorubicin (DOX), a chemotherapy drug, via hydrophobic, π-π stacking and charge interactions. The attained HA/PDA-covered DOX-carrying FZ NMs (HPDFZ NMs) promoted DOX and Fe2+ release in weakly acidic and GSH-rich milieu and exhibited acidity-activated •OH generation. Through efficient CD44-mediated endocytosis, the HPDFZ NMs internalized by CT26 cells not only prominently enhanced •OH accumulation by consuming GSH via PDA-mediated Michael addition combined with Fe2+/Fe3+ redox couple to cause mitochondria damage and lipid peroxidation, but also achieved intracellular DOX release, thus eliciting apoptosis and ferroptosis. Importantly, the HPDFZ NMs potently inhibited CT26 tumor growth in vivo at a low DOX dose and had good biosafety, thereby showing promising potential in tumor-specific treatment.

Nanoscale Metal-Organic Frameworks as a Photoluminescent Platform for Bioimaging and Biosensing Applications.

The tracking of nanomedicines in their concentration and location inside living systems has a pivotal effect on the understanding of the biological processes, early-stage diagnosis, and therapeutic monitoring of diseases. Nanoscale metal-organic frameworks (nano MOFs) possess high surface areas, definite structure, regulated optical properties, rich functionalized sites, and good biocompatibility that allow them to excel in a wide range of biomedical applications. Controllable syntheses and functionalization endow nano MOFs with better properties as imaging agents and sensing units for the diagnosis and treatment of diseases. This minireview summarizes the tunable synthesis strategies of nano MOFs with controllable size, shape, and regulated luminescent performance, and pinpoints their recent advanced applications as optical elements in bioimaging and biosensing. The current limitations and future development directions of nano MOF-contained materials in bioimaging and biosensing applications are also discussed, aiming to expand the biological applications of nano MOF-based nanomedicine and facilitate their production or clinical translation.

Defect-Engineered Metal-Organic Frameworks as Nanocarriers for Pharmacotherapy: Insights into Intracellular Dynamics at The Single Particle Level.

Nanoscale Metal-Organic Frameworks (nanoMOFs) are widely implemented in a host of assays involving drug delivery, biosensing catalysis, and bioimaging. However, the cell pathways and cell fate remain poorly understood. Here, a new fluorescent nanoMOF integrating ATTO 655 into surface defects of colloidal UiO-66 is synthesized, allowing to track the spatiotemporal localization of Single nanoMOF in live cells. Density functional theory reveals the stronger binding of ATTO 655 to the Zr6 cluster nodes compared with phosphate and Alendronate Sodium. Parallelized tracking of the spatiotemporal localization of thousands of nanoMOFs and analysis using machine learning platforms reveals whether nanoMOFs remain outside as well as their cellular internalization pathways. To quantitatively assess their colocalization with endo/lysosomal compartments, a colocalization proxy approach relying on the nanoMOF detection of particles in one channel to the signal in the corresponding endo/lysosomal compartments channel, considering signal versus local background intensity ratio and signal-to-noise ratio is developed. This strategy mitigates colocalization value inflation from high or low signal expression in endo/lysosomal compartments. The results accurately measure the nanoMOFs' colocalization from early to late endosomes and lysosomes and emphasize the importance of understanding their intracellular dynamics based on single-particle tracking for optimal and safe drug delivery.

Application of nanoscale metal–organic frameworks in tumor immunotherapy

Application of nanoscale metal–organic frameworks in tumor immunotherapy

An intelligent and self-assembled nanoscale metal organic framework (99mTC-DOX loaded Fe3O4@FeIII-tannic acid) for tumor targeted chemo/chemodynamic theranostics

BackgroundRecent advances in clinical transformation research have focused on chemodynamic theranostics as an emerging strategy for tackling cancer. Nevertheless, its effectiveness is hampered by the tumor's glutathione antioxidant effect, poor acidic tumor microenvironment (TME) and inadequate endogenous H2O2. Hence, we designed an activatable theranostics (99mTc-DOX loaded AA-Fe3O4@FeIII-TA) that effectively boost the catalytic efficiency of the Fenton-reaction-induced ROS production and augment the chemotherapeutic efficacy combined with diagnostic action.ResultsA cross-linked matrix of tannic acid-ferric salt (FeIII-TA) as a pH-responsive shell onto ascorbic acid-decorated iron-oxide nanoparticles (AA-Fe3O4NPs) was prepared demonstrating a metal–organic- framework (MOF) nanostructure, followed by loading of 99mTc-labelled DOX. The platform (99mTc-DOX loaded AA-Fe3O4@FeIII-TA) displayed suitable physical–chemical properties, including 69.8 nm particle size, 94.8 nm hydrodynamic size, − 21 mV zeta potential, effective FeIII-TA shell crosslinking onto AA-Fe3O4NPs and 94% loading efficiency for 99mTc-DOX. The results of the in-vitro release investigations showed that the platform exhibited a pH-dependent release manner with 98.3% of the 99mTc-DOX being released at pH 5 (simulating the tumor’s pH) and only 10% being released at the physiological pH (pH 7.4). This indicates that there was negligible payload leakage into the systemic circulation during the platform's passive accumulation inside tumor. Due to the acidic TME nature, the MOF shell might be degraded releasing free FeIII, TA and a sustained release of 99mTc-DOX. Besides its chemotherapeutic impact and capacity to raise intracellular H2O2 content, the released 99mTc-DOX might be used as SPECT imaging tracer for concurrent tumor diagnosis. Furthermore, the mild acidity of the tumor may be overcome by the released TA, which might raise the acidification level of cancer cells. The released FeIII, TA and the endogenous GSH could engage in a redox reaction that depletes GSH and reduces FeIII to FeII ions which subsequently catalyze the elevated concentration of H2O2 to reactive •OH via Fenton-like reaction, increasing the effectiveness of chemodynamic therapy. Moreover, the in-vivo evaluation in tumor-bearing mice showed significant radioactivity accumulation in the tumor lesion (16.8%ID/g at 1 h post-injection) with a potential target/non-target ratio of 8.ConclusionsThe 99mTc-DOX loaded AA-Fe3O4@FeIII-TA could be introduced as an effective chemo/chemodynamic theranostics.Graphical

Metal-Organic Frameworks: Unconventional Nanoweapons against COVID.

The SARS-CoV-2 (COVID-19) pandemic outbreak led to enormous social and economic repercussions worldwide, felt even to this date, making the design of new therapies to combat fast-spreading viruses an imperative task. In the face of this, diverse cutting-edge nanotechnologies have risen as promising tools to treat infectious diseases such as COVID-19, as well as challenging illnesses such as cancer and diabetes. Aside from these applications, nanoscale metal-organic frameworks (nanoMOFs) have attracted much attention as novel efficient drug delivery systems for diverse pathologies. However, their potential as anti-COVID-19 therapeutic agents has not been investigated. Herein, we propose a pioneering anti-COVID MOF approach by studying their potential as safe and intrinsically antiviral agents through screening various nanoMOF. The iron(III)-trimesate MIL-100 showed a noteworthy antiviral effect against SARS-CoV-2 at the micromolar range, ensuring a high biocompatibility profile (90% of viability) in a real infected human cellular scenario. This research effectively paves the way toward novel antiviral therapies based on nanoMOFs, not only against SARS-CoV-2 but also against other challenging infectious and/or pulmonary diseases.