Sustained and targeted delivery of checkpoint inhibitors by metal-organic frameworks for cancer immunotherapy

Drug carrier wonders: Synthetic strategies of zeolitic imidazolates frameworks (ZIFs) and their applications in drug delivery and anti-cancer activity

With the rapid advancement of nanotechnology, stimuli-responsive nanomaterials have emerged as a feasible choice for the designing of controlled drug delivery systems. Zeolitic imidazolates frameworks are a subclass of Metal-organic frameworks (MOFs) that are recognized by their excellent porosity, structural tunability and chemical modifications make them promising materials for loading targeted molecules and therapeutics agents. The biomedical industry uses these porous materials extensively as nano-carriers in drug delivery systems. These MOFs not only possess excellent targeted imaging ability but also cause the death of tumor cells drawing considerable attention in the current framework of anticancer drug delivery systems. In this review, the outline of stability, porosity, mechanism of encapsulation and release of anticancer drug have been reported extensively. In the end, we also discuss a brief outline of current challenges and future perspectives of ZIFs in the biomedical world.

Metal-organic frameworks for biomedical applications: A review

Metal-organic frameworks (MOFs) are emergent materials in diverse prospective biomedical uses, owing to their inherent features such as adjustable pore dimension and volume, well-defined active sites, high surface area, and hybrid structures. The multifunctionality and unique chemical and biological characteristics of MOFs allow them as ideal platforms for sensing numerous emergent biomolecules with real-time monitoring towards the point-of-care applications. This review objects to deliver key insights on the topical developments of MOFs for biomedical applications. The rational design, preparation of stable MOF architectures, chemical and biological properties, biocompatibility, enzyme-mimicking materials, fabrication of biosensor platforms, and the exploration in diagnostic and therapeutic systems are compiled. The state-of-the-art, major challenges, and the imminent perspectives to improve the progressions convoluted outside the proof-of-concept, especially for biosensor platforms, imaging, and photodynamic therapy in biomedical research are also described. The present review may excite the interdisciplinary studies at the juncture of MOFs and biomedicine.

Cancer Cell-Selective PD-L1 Inhibition via a DNA Safety Catch to Enhance Immunotherapy Specificity

Immune checkpoint protein blockade (ICB) has emerged as a powerful immunotherapy approach, but suppressing immune-related adverse events (irAEs) for noncancerous cells and normal tissues remains challenging. Activatable ICB has been developed with tumor microenvironment highly-expressed molecules as stimuli, but they still lack precision and efficiency considering the diffusion of stimuli molecules in whole tumor tissue. Here we assemble PD-L1 with a duplex DNA strand, termed as "safety catch", to regulate its accessibility for ICB. The safety catch remains at "on" status for noncancerous cells to prevent ICB binding to PD-L1. Cancer cell membrane protein c-Met acts as a trigger protein to react with safety catch, which selectively exposes its hybridization region for ICB reagent. The ICB reagent is a retractable DNA nanostring with repeating hairpin-structural units, whose contraction drives PD-L1 clustering with endocytosis-guided degradation. The safety catch, even remained at "safety on" status, is removed from the cell membrane via a DNA strand displacement reaction to minimize its influence on noncancerous cells. This strategy demonstrates selective and potent immunotherapeutic capabilities only against cancer cells both in vitro and in vivo, and shows effective suppression of irAEs in normal tissues, therefore would become a promising approach for precise immunotherapy in mice.

A biomimetic camouflaged metal organic framework for enhanced siRNA delivery in the tumor environment

Gene silencing through RNA interference (RNAi), particularly using small double-stranded RNA (siRNA), has been identified as a potent strategy for targeted cancer treatment. Yet, its application faces challenges such as nuclease degradation, inefficient cellular uptake, endosomal entrapment, off-target effects, and immune responses, which have hindered its effective delivery. In the past few years, these challenges have been addressed significantly by using camouflaged metal-organic framework (MOF) nanocarriers. These nanocarriers protect siRNA from degradation, enhance cellular uptake, and reduce unintended side effects by effectively targeting desired cells while evading immune detection. By combining the properties of biomimetic membranes and MOFs, these nanocarriers offer superior benefits such as extended circulation times, enhanced stability, and reduced immune responses. Moreover, through ligand-receptor interactions, biomimetic membrane-coated MOFs achieve homologous targeting, minimizing off-target adverse effects. The MOFs, acting as the core, efficiently encapsulate and protect siRNA molecules, while the biomimetic membrane-coated surface provides homologous targeting, further increasing the precision of siRNA delivery to cancer cells. In particular, the biomimetic membranes help to shield the MOFs from the immune system, avoiding unwanted immune responses and improving their biocompatibility. The combination of siRNA with innovative nanocarriers, such as camouflaged-MOFs, presents a significant advancement in cancer therapy. The ability to deliver siRNA with precision and effectiveness using these camouflaged nanocarriers holds great promise for achieving more personalized and efficient cancer treatments in the future. This review article discusses the significant progress made in the development of siRNA therapeutics for cancer, focusing on their effective delivery through novel nanocarriers, with a particular emphasis on the role of metal-organic frameworks (MOFs) as camouflaged nanocarriers.

Metal-Organic Framework-Mediated Delivery of Nucleic Acid across Intact Plant Cells

Plant synthetic biology is applied in sustainable agriculture, clean energy, and biopharmaceuticals, addressing crop improvement, pest resistance, and plant-based vaccine production by introducing exogenous genes into plants. This technique faces challenges delivering genes due to plant cell walls and intact cell membranes. Novel approaches are required to address this challenge, such as utilizing nanomaterials known for their efficiency and biocompatibility in gene delivery. This work investigates metal-organic frameworks (MOFs) for gene delivery in intact plant cells by infiltration. Hence, small-sized ZIF-8 nanoparticles (below 20 nm) were synthesized and demonstrated effective DNA/RNA delivery into Nicotiana benthamiana leaves and Arabidopsis thaliana roots, presenting a promising and simplified method for gene delivery in intact plant cells. We further demonstrate that small-sized ZIF-8 nanoparticles protect RNA from RNase degradation and successfully silence an endogenous gene by delivering siRNA in N. benthamiana leaves.

Nano-Drug Delivery Systems Targeting CAFs: A Promising Treatment for Pancreatic Cancer

Currently, pancreatic cancer (PC) is one of the most lethal malignant tumors. PC is typically diagnosed at a late stage, exhibits a poor response to conventional treatment, and has a bleak prognosis. Unfortunately, PC's survival rate has not significantly improved since the 1960s. Cancer-associated fibroblasts (CAFs) are a key component of the pancreatic tumor microenvironment (TME). They play a vital role in maintaining the extracellular matrix and facilitating the intricate communication between cancer cells and infiltrated immune cells. Exploring therapeutic approaches targeting CAFs may reverse the current landscape of PC therapy. In recent years, nano-drug delivery systems have evolved rapidly and have been able to accurately target and precisely release drugs with little or no toxicity to the whole body. In this review, we will comprehensively discuss the origin, heterogeneity, potential targets, and recent advances in the nano-drug delivery system of CAFs in PC. We will also propose a novel integrated treatment regimen that utilizes a nano-drug delivery system to target CAFs in PC, combined with radiotherapy and immunotherapy. Additionally, we will address the challenges that this regimen currently faces.

Radiation Synergizes with IL2/IL15 Stimulation to Enhance Innate Immune Activation and Antitumor Immunity

Ionizing radiation is known to possess immune modulatory properties. However, how radiotherapy (RT) may complement with different types of immunotherapies to boost antitumor responses is unclear. In mice implanted with EO771 syngeneic tumors, NL-201 a stable, highly potent CD25-independent agonist to IL2 and IL15 receptors with enhanced affinity for IL2Rβγ was given with or without RT. Flow analysis and Western blot analysis was performed to determine the mechanisms involved. STING (-/-) and CD11c+ knockout mice were implanted with EO771 tumors to confirm the essential signaling and cell types required to mediate the effects seen. Combination of RT and NL-201 to enhance systemic immunotherapy with an anti-PD-1 checkpoint inhibitor was utilized to determine tumor growth inhibition and survival, along characterization of tumor microenvironment as compared with all other treatment groups. Here, we showed that RT, synergizing with NL-201 produced enhanced antitumor immune responses in murine breast cancer models. When given together, RT and NL-201 enhanced activation of the cytosolic DNA sensor cyclic GMP-AMP synthase-stimulator of IFN genes (cGAS-STING) pathway, resulting in increased type I IFN production in dendritic cells (DC), and consequently greater tumor infiltration and more efficient priming of antigen-specific T cells. The immune stimulatory mechanisms triggered by NL-201 and RT resulted in superior tumor growth inhibition and survival benefit in both localized and metastatic cancers. Our results support further preclinical and clinical investigation of this novel synergism regimen in locally advanced and metastatic settings.

Advances in Immunomodulatory MOFs for Biomedical Applications

Given the crucial role of immune system in the occurrence and progression of various diseases such as cancer, wound healing, bone defect, and inflammation-related diseases, immunomodulation is recognized as a potential solution for treatment of these diseases. Immunomodulation includes both immunosuppression in hyperactive immune conditions and immune activation in hypoactive conditions. For these purposes, metal-organic frameworks (MOFs) are investigated to modulate immune responses either by their own bioactivities or by delivering immunomodulatory agents due to their excellent biodegradability and high delivery capacity. This review starts with an overview of the synthesis strategies of immunomodulatory MOFs, followed by a summarization on the latest applications of immunomodulatory MOFs in cancer immunomodulatory, wound healing, inflammatory disease, and bone tissue engineering. A variety of design considerations, in order to optimize immunomodulatory properties and efficacy of MOFs, is also involved. Last, the challenges and perspectives of future research, which are expected to provide researchers with new insight into the design and application of immunomodulatory MOFs, are discussed.

Ultrathin Clay Nanoparticles-Mediated Mutual Reinforcement of Ferroptosis and Cancer Immunotherapy

Ferroptosis-triggered immunogenic cell death (ICD) is widely adopted to potentiate the body's antitumor immunity by catalyzing the production of toxic reactive oxygen species (ROS). However, the efficacy of ferroptosis and immunotherapy is greatly restricted by intracellular abundant glutathione (GSH) and immunosuppressive tumor microenvironment (TME). Herein, a facile bottom-up method for solvent-free synthesis of ultrathin manganese (Mn)-based layered double hydroxide nanosheets with high loading efficiency for pro-inflammatory cytokine interferon (IFNγ) (IFNγ/uMn-LDHs) is proposed to mutually reinforce the ferroptosis and systemic immunity. The introduction of manganese ions significantly contributes to GSH depletion and hydroxyl radical generation, which can be further enhanced by IFNγ delivery-induced SLC7A11 downregulation. The ICD effect after cell ferroptosis cooperates with the intrinsic immunomodulatory property of IFNγ/uMn-LDHs to facilitate the maturation of dendritic cells (DCs) and the priming of T cells. IFNγ secretion from activated CD8+ T cells in turn involves cascade immunogenic ferroptosis, thus constructing a closed-loop therapy. Remarkably, a potent abscopal effect is observed in the growth inhibition of both primary and distant tumors. Overall, the ultrathin Mn-based clay nanoplatform provides a simple approach for mutual regulation between ferroptosis and antitumor immune response, overcoming the obstacles of current cancer immunotherapy.

A critical review on metal-organic frameworks (MOFs) based nanomaterials for biomedical applications: Designing, recent trends, challenges, and prospects

Nanomaterials (NMs) have garnered significant attention in recent decades due to their versatile applications in a wide range of fields. Thanks to their tiny size, enhanced surface modifications, impressive volume-to-surface area ratio, magnetic properties, and customized optical dispersion. NMs experienced an incredible upsurge in biomedical applications including diagnostics, therapeutics, and drug delivery. This minireview will focus on notable examples of NMs that tackle important issues, demonstrating various aspects such as their design, synthesis, morphology, classification, and use in cutting-edge applications. Furthermore, we have classified and outlined the distinctive characteristics of the advanced NMs as nanoscale particles and hybrid NMs. Meanwhile, we emphasize the incredible potential of metal-organic frameworks (MOFs), a highly versatile group of NMs. These MOFs have gained recognition as promising candidates for a wide range of bio-applications, including bioimaging, biosensing, antiviral therapy, anticancer therapy, nanomedicines, theranostics, immunotherapy, photodynamic therapy, photothermal therapy, gene therapy, and drug delivery. Although advanced NMs have shown great potential in the biomedical field, their use in clinical applications is still limited by issues such as stability, cytotoxicity, biocompatibility, and health concerns. This review article provides a thorough analysis offering valuable insights for researchers investigating to explore new design, development, and expansion opportunities. Remarkably, we ponder the prospects of NMs and nanocomposites in conjunction with current technology.

A new era in cancer treatment: harnessing ZIF-8 nanoparticles for PD-1 inhibitor delivery

This review delves into the potential of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles in augmenting the efficacy of cancer immunotherapy, with a special focus on the delivery of programmed cell death receptor 1 (PD-1) inhibitors. The multifunctional nature of ZIF-8 nanoparticles as drug carriers is emphasized, with their ability to encapsulate a range of therapeutic agents, including PD-1 inhibitors, and facilitate their targeted delivery to tumor locations. By manipulating the pore size and surface characteristics of ZIF-8 nanoparticles, controlled drug release can be realized. The strategic use of ZIF-8 nanoparticles to deliver PD-1 inhibitors presents a precise and targeted modality for cancer treatment, reducing off-target impacts and enhancing therapeutic effectiveness. This combined strategy addresses the existing challenges and constraints of current immunotherapy techniques, with the ultimate goal of enhancing patient outcomes in cancer therapy.

Drug delivery methods for cancer immunotherapy

Despite the fact that numerous immunotherapy-based drugs have been approved by the FDA for the treatment of primary and metastatic tumors, only a small proportion of the population can benefit from them because of primary and acquired resistances. Moreover, the translation of immunotherapy from the bench to the clinical practice is being challenging because of the short half-lives of the involved molecules, the difficulties to accomplish their delivery to the target sites, and some serious adverse effects that are being associated with these approaches. The emergence of drug delivery vehicles in the field of immunotherapy is helping to overcome these difficulties and limitations and this review describes how, providing some illustrative examples. Moreover, this article provides an exhaustive review of the studies that have been published to date on the particular case of hematological cancers. (Created with BioRender).

Histidine-Rich Protein Accelerates the Biomineralization of Zeolitic Imidazolate Frameworks for In Vivo Protein Delivery

Biomineralization of metal-organic frameworks (MOFs) provides a powerful approach for intracellular protein delivery, enabling the study of biological function and therapeutic potential of proteins. However, the potency of this approach is largely challenged by the low efficiency of current strategies for interfacing proteins with MOFs for biomineralization and intracellular delivery. Here, we report a versatile and convenient biomineralization strategy for the rapid encapsulation and enhanced delivery of proteins using MOFs, accelerated by histidine-rich proteins. We demonstrate that the histidine-rich green fluorescent protein (H39GFP) can accelerate the biomineralization of MOFs by promoting the coordination between proteins and metal ions, leading to enhanced protein delivery efficiency up to 15-fold. Moreover, we show that the delivery of H39GFP-fused cytotoxic ribonuclease and bacterial-derived RAS protease can effectively inhibit tumor cell growth. The strategy of promoting the biomineralization of MOFs via histidine-rich proteins for enhanced intracellular delivery could be expanded to other biomacromolecules, advancing their therapeutic potential and the biomedical scope of MOFs.

Nanoparticles in Medicine: Current Status in Cancer Treatment

Cancer is still a leading cause of deaths worldwide, especially due to those cases diagnosed at late stages with metastases that are still considered untreatable and are managed in such a way that a lengthy chronic state is achieved. Nanotechnology has been acknowledged as one possible solution to improve existing cancer treatments, but also as an innovative approach to developing new therapeutic solutions that will lower systemic toxicity and increase targeted action on tumors and metastatic tumor cells. In particular, the nanoparticles studied in the context of cancer treatment include organic and inorganic particles whose role may often be expanded into diagnostic applications. Some of the best studied nanoparticles include metallic gold and silver nanoparticles, quantum dots, polymeric nanoparticles, carbon nanotubes and graphene, with diverse mechanisms of action such as, for example, the increased induction of reactive oxygen species, increased cellular uptake and functionalization properties for improved targeted delivery. Recently, novel nanoparticles for improved cancer cell targeting also include nanobubbles, which have already demonstrated increased localization of anticancer molecules in tumor tissues. In this review, we will accordingly present and discuss state-of-the-art nanoparticles and nano-formulations for cancer treatment and limitations for their application in a clinical setting.

Innovative Metal-Organic Frameworks for Targeted Oral Cancer Therapy: A Review

Metal-organic frameworks (MOFs) have proven to be very effective carriers for drug delivery in various biological applications. In recent years, the development of hybrid nanostructures has made significant progress, including developing an innovative MOF-loaded nanocomposite with a highly porous structure and low toxicity that can be used to fabricate core-shell nanocomposites by combining complementary materials. This review study discusses using MOF materials in cancer treatment, imaging, and antibacterial effects, focusing on oral cancer cells. For patients with oral cancer, we offer a regular program for accurately designing and producing various anticancer and antibacterial agents to achieve maximum effectiveness and the lowest side effects. Also, we want to ensure that the anticancer agent works optimally and has as few side effects as possible before it is tested in vitro and in vivo. It is also essential that new anticancer drugs for cancer treatment are tested for efficacy and safety before they go into further research.

Rhodamine B-Conjugated Fluorescent Block Copolymer Micelles for Efficient Chlorambucil Delivery and Intracellular Imaging

The clinical development of the anticancer drug chlorambucil (CHL) is limited by its low solubility in water, poor bioavailability, and off-target toxicity. Besides, another constraint for monitoring intracellular drug delivery is the non-fluorescent nature of CHL. Nanocarriers based on block copolymers of poly(ethylene glycol)/poly(ethylene oxide) (PEG/PEO) and poly(ε-caprolactone) (PCL) are an elegant choice for drug delivery applications due to their high biocompatibility and inherent biodegradability properties. Here, we have designed and prepared block copolymer micelles (BCM) containing CHL (BCM-CHL) from a block copolymer having fluorescent probe rhodamine B (RhB) end-groups to achieve efficient drug delivery and intracellular imaging. For this purpose, the previously reported tetraphenylethylene (TPE)-containing poly(ethylene oxide)-b-poly(ε-caprolactone) [TPE-(PEO-b-PCL)₂] triblock copolymer was conjugated with RhB by a feasible and effective post-polymerization modification method. In addition, the block copolymer was obtained by a facile and efficient synthetic strategy of one-pot block copolymerization. The amphiphilicity of the resulting block copolymer TPE-(PEO-b-PCL-RhB)₂ led to the spontaneous formation of micelles (BCM) in aqueous media and successful encapsulation of the hydrophobic anticancer drug CHL (CHL-BCM). Dynamic light scattering and transmission electron microscopy analyses of BCM and CHL-BCM revealed a favorable size (10-100 nm) for passive targeting of tumor tissues via the enhanced permeability and retention effect. The fluorescence emission spectrum (λ_ex 315 nm) of BCM demonstrated Förster resonance energy transfer between TPE aggregates (donor) and RhB (acceptor). On the other hand, CHL-BCM revealed TPE monomer emission, which may be attributed to the π-π stacking interaction between TPE and CHL molecules. The in vitro drug release profile showed that CHL-BCM exhibits drug release in a sustained manner over 48 h. A cytotoxicity study proved the biocompatibility of BCM, while CHL-BCM revealed significant toxicity to cervical (HeLa) cancer cells. The inherent fluorescence of RhB in the block copolymer offered an opportunity to directly monitor the cellular uptake of the micelles by confocal laser scanning microscopy imaging. These results demonstrate the potential of these block copolymers as drug nanocarriers and as bioimaging probes for theranostic applications.

Biocompatible and biodegradable copper-protocatechuic metal-organic frameworks as rifampicin carrier

Tuberculosis (TB) is a disease caused by the M. tuberculosis bacteria infection and is listed as one of the deadliest diseases to date. Despite the development of antituberculosis drugs, the need for long-term drug consumption and low patient commitment are obstacles to the success of TB treatment. A continuous drug delivery system that has a long-term effect is needed to reduce routine drug consumption intervals, suppress infection, and prevent the emergence of drug-resistant strains of M. tuberculosis. For this reason, biomolecule metal-organic framework (BioMOF) with good biocompatibility, nontoxicity, bioactivity, and high stability are becoming potential drug carriers. This study used a bioactive protocatechuic acid (PCA) as organic linker to prepare copper-based BioMOF Cu-PCA under base-modulated conditions. Detailed crystal analysis by the powder X-ray diffraction demonstrated that the Cu-PCA, with a chemical formula of C₁₄H₁₆O₁₃Cu₃, crystalizes as triclinic in space group P1. Comprehensive physicochemical characterizations were provided using FTIR, SEM, XPS, TGA, EA, and N₂ sorption. As a drug carrier, Cu-PCA showed a high maximum rifampicin (RIF) drug loading of 443.01 mg/g. Upon resuspension in PBS, the RIF and linkers release profile exhibited two-stage release kinetic profiles, which are well described by the Biphasic Dose Response (BiDoseResp) model. A complete release of these compounds (RIF and PCA) was achieved after ~9 h of mixing in PBS. Cu-PCA and RIF@Cu-PCA possessed antibacterial activity against Escherichia coli, and good biocompatibility is evidenced by the high viability of MH-S mice alveolar macrophage cells upon supplementations.

Hybrid Nanomaterials for Cancer Immunotherapy

Nano-immunotherapy has been recognized as a highly promising strategy for cancer treatment in recent decades, which combines nanotechnology and immunotherapy to combat against tumors. Hybrid nanomaterials consisting of at least two constituents with distinct compositions and properties, usually organic and inorganic, have been engineered with integrated functions and enormous potential in boosting cancer immunotherapy. This review provides a summary of hybrid nanomaterials reported for cancer immunotherapy, including nanoscale metal-organic frameworks, metal-phenolic networks, mesoporous organosilica nanoparticles, metallofullerene nanomaterials, polymer-lipid, and biomacromolecule-based hybrid nanomaterials. The combination of immunotherapy with chemotherapy, chemodynamic therapy, radiotherapy, radiodynamic therapy, photothermal therapy, photodynamic therapy, and sonodynamic therapy based on hybrid nanomaterials is also discussed. Finally, the current challenges and the prospects for designing hybrid nanomaterials and their application in cancer immunotherapy are outlined.

Nanomedicine embraces cancer radio-immunotherapy: mechanism, design, recent advances, and clinical translation

Cancer radio-immunotherapy, integrating external/internal radiation therapy with immuno-oncology treatments, emerges in the current management of cancer. A growing number of pre-clinical studies and clinical trials have recently validated the synergistic antitumor effect of radio-immunotherapy, far beyond the "abscopal effect", but it suffers from a low response rate and toxicity issues. To this end, nanomedicines with an optimized design have been introduced to improve cancer radio-immunotherapy. Specifically, these nanomedicines are elegantly prepared by incorporating tumor antigens, immuno- or radio-regulators, or biomarker-specific imaging agents into the corresponding optimized nanoformulations. Moreover, they contribute to inducing various biological effects, such as generating in situ vaccination, promoting immunogenic cell death, overcoming radiation resistance, reversing immunosuppression, as well as pre-stratifying patients and assessing therapeutic response or therapy-induced toxicity. Overall, this review aims to provide a comprehensive landscape of nanomedicine-assisted radio-immunotherapy. The underlying working principles and the corresponding design strategies for these nanomedicines are elaborated by following the concept of "from bench to clinic". Their state-of-the-art applications, concerns over their clinical translation, along with perspectives are covered.

Systematic design of cell membrane coating to improve tumor targeting of nanoparticles

Cell membrane (CM) coating technology is increasingly being applied in nanomedicine, but the entire coating procedure including adsorption, rupture, and fusion is not completely understood. Previously, we showed that the majority of biomimetic nanoparticles (NPs) were only partially coated, but the mechanism underlying this partial coating remains unclear, which hinders the further improvement of the coating technique. Here, we show that partial coating is an intermediate state due to the adsorption of CM fragments or CM vesicles, the latter of which could eventually be ruptured under external force. Such partial coating is difficult to self-repair to achieve full coating due to the limited membrane fluidity. Building on our understanding of the detailed coating process, we develop a general approach for fixing the partial CM coating: external phospholipid is introduced as a helper to increase CM fluidity, promoting the final fusion of lipid patches. The NPs coated with this approach have a high ratio of full coating (~23%) and exhibit enhanced tumor targeting ability in comparison to the NPs coated traditionally (full coating ratio of ~6%). Our results provide a mechanistic basis for fixing partial CM coating towards enhancing tumor accumulation.

A Two-Pronged Strategy for Enhanced Deep-Tumor Penetration and NIR-II Multimodal Imaging-Monitored Photothermal Therapy

The second near-infrared (NIR-II)-induced photothermal therapy (PTT) has attracted a great deal of attention in recent years due to its non-invasiveness and because it uses less energy. However, the penetration of photothermal agents into solid tumors is seriously impeded by the dense-tumor extracellular matrix (ECM) containing cross-linked hyaluronic acid (HA), thereby compromising the ultimate therapeutic effects. Herein, acid-labile metal-organic frameworks were employed as nanocarriers to efficiently mineralize hyaluronidase (HAase) and encapsulate Ag₂S nanodots by a one-pot approach under mild conditions. The obtained nanocomposites (AHZ NPs) maintained enzyme activity and changed in size to prolong blood circulation and complete delivery of the cargo to the tumor. Moreover, the released HAase could specifically break out the HA to loosen ECM and enable the Ag₂S nanodots to breeze through the tumor matrix space and gain access to the deep tumor. Under near-infrared laser irradiation, the AHZ NPs displayed remarkable fluorescence, outstanding photoacoustic signals, and excellent photothermal properties in the whole tumor. This work offers a promising two-pronged strategy via a decrease in nanoparticle size and the degradation of dense ECM for NIR-II multimodal imaging-guided PTT of deep tumors.

Boosting Protein Encapsulation through Lewis-Acid-Mediated Metal-Organic Framework Mineralization: Toward Effective Intracellular Delivery

Encapsulation of biomolecules using metal-organic frameworks (MOFs) to form stable biocomposites has been demonstrated to be a valuable strategy for their preservation and controlled release, which has been however restricted to specific electrostatic surface conditions. We present a Lewis-acid-mediated general in situ strategy that promotes the spontaneous MOF growth on a broad variety of proteins, for the first time, regardless of their surface nature. We demonstrate that MOFs based on cations exhibiting considerable inherent acidity such as MIL-100(Fe) enable efficient biomolecule encapsulation, including elusive alkaline proteins previously inaccessible by the well-developed in situ azolate-based MOF encapsulation. Specifically, we prove the MIL-100(Fe) scaffold for the encapsulation of a group of proteins exhibiting very different isoelectric points (5 < pI < 11), allowing triggered release under biocompatible conditions and retaining their activity after exposure to denaturing environments. Finally, we demonstrate the potential of the myoglobin-carrying biocomposite to facilitate the delivery of O₂ into hypoxic human lung carcinoma A549 cells, overcoming hypoxia-associated chemoresistance.

Metal-organic frameworks for pharmaceutical and biomedical applications

Metal-organic framework (MOF) materials provide unprecedented opportunities for evaluating valuable compounds for various medical applications. MOFs merged with biomolecules, used as novel biomaterials, have become particularly useful in biological environments. Bio-MOFs can be promising materials in the global to avoid utilization above toxicological substances. Bio-MOFs with crystallin and porosity nature offer flexible structure via bio-linker and metal node variation, which improves their wide applicability in medical science.

Cancer cell membrane-wrapped nanoparticles for cancer immunotherapy: A review of current developments

Background

As the forefront of nanomedicine, bionic nanotechnology has been widely used for drug delivery in order to obtain better efficacy but less toxicity for cancer treatments. With the rise of immunotherapy, the combination of nanotechnology and immunotherapy will play a greater potential of anti-tumor therapy. Due to its advantage of homologous targeting and antigen library from source cells, cancer cell membrane (CCM)-wrapped nanoparticles (CCNPs) has become an emerging topic in the field of immunotherapy.

Key scientific concepts of review

CCNP strategies include targeting or modulating the tumor immune microenvironment and combination therapy with immune checkpoint inhibitors and cancer vaccines. This review summarizes the current developments in CCNPs for cancer immunotherapy and provides insight into the challenges of transferring this technology from the laboratory to the clinic as well as the potential future of this technology.

Conclusion

This review described CCNPs have enormous potential in cancer immunotherapy, but there are still challenges in terms of translating their effects in vitro to the clinical setting. We believe that these challenges can be addressed in the future with a focus on individualized treatment with CCNPs as well as CCNPs combined with other effective treatments.

A comparative study of the toxic effect of ZIF-8 and ZIF-L on the colonization and decomposition of shaded outdoor mice carrions by arthropods

Metal–organic frameworks (MOFs) are promising materials for several applications. Thus, they have been intensively reported and commercialized by several international companies. However, little is known about the fate and risk of MOFs to living organisms. Here, the toxic effect of two Zinc (Zn)-based MOFs; zeolitic imidazolate frameworks (ZIF-8) and leaf-like ZIF (ZIF-L), was tested to investigate the impact of the postmortem period of mice carrions and arthropods which found in decomposing carrions. The data analysis revealed an increase in zinc content over time. Toxicology in forensics studies biological materials for the presence of poisons, such as pharmaceuticals. The toxicology report can provide important details about the types of chemicals present in a person and whether the amount of those substances is in line with a therapeutic dose or exceeds a dangerous level. These findings conclude the possible fate and impact after mortality. This study presents the first study of the toxic effect of ZIFs materials using mice carrions and arthropods (Sarcophaga sp. Larvae) via morphological and microscopic studies compared with control, providing important biological information could aid in the environmental impact of the toxic level of MOF materials.

Nanoscale Zeolitic Imidazolate Framework (ZIF)–8 in Cancer Theranostics: Current Challenges and Prospects

Simple Summary

The biomedical application of metal–organic frameworks in cancer theranostics has become a research hotspot with rapid progress. As a typical representative, ZIF–8 attracts increasing interest from researchers due to its good performance and potential. In this review, we updated recent discoveries on the ZIF–8–based nanoplatforms for cancer, discussed the problems in current research and the obstacles for clinical translation of ZIF–8, and also proposed an outlook on its future development.

Abstract

Cancer severely threatens human health and has remained the leading cause of disease–related death for decades. With the rapid advancement of nanomedicine, nanoscale metal–organic frameworks are believed to be potentially applied in the treatment and biomedical imaging for various tumors. Zeolite imidazole framework (ZIF)–8 attracts increasing attention due to its high porosity, large specific surface area, and pH–responsiveness. The designs and modifications of ZIF–8 nanoparticles, as well as the strategy of drug loading, demand a multifaceted and comprehensive understanding of nanomaterial features and tumor characteristics. We searched for studies on ZIF–8–based nanoplatforms in tumor theranostics on Web of Science from 2015 to 2022, mainly focused on the research published in the past 3 years, summarized the progress of their applications in tumor imaging and treatment, and discussed the favorable aspects of ZIF–8 nanoparticles for tumor theranostics as well as the future opportunities and potential challenges. As a kind of metal–organic framework material full of potential, ZIF–8 can be expected to be combined with more therapeutic systems in the future and continue to contribute to all aspects of tumor therapy and diagnosis.

Cancer immunotherapy based on image-guided STING activation by nucleotide nanocomplex-decorated ultrasound microbubbles

The cytosolic innate immune sensor cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is crucial for priming adaptive antitumour immunity through antigen-presenting cells (APCs). Natural agonists, such as cyclic dinucleotides (CDNs), activate the cGAS-STING pathway, but their clinical translation is impeded by poor cytosolic entry and serum stability, low specificity and rapid tissue clearance. Here we developed an ultrasound (US)-guided cancer immunotherapy platform using nanocomplexes composed of 2'3'-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) electrostatically bound to biocompatible branched cationic biopolymers that are conjugated onto APC-targeting microbubbles (MBs). The nanocomplex-conjugated MBs engaged with APCs and efficiently delivered cGAMP into the cytosol via sonoporation, resulting in activation of cGAS-STING and downstream proinflammatory pathways that efficiently prime antigen-specific T cells. This bridging of innate and adaptive immunity inhibited tumour growth in both localized and metastatic murine cancer models. Our findings demonstrate that targeted local activation of STING in APCs under spatiotemporal US stimulation results in systemic antitumour immunity and improves the therapeutic efficacy of checkpoint blockade, thus paving the way towards novel image-guided strategies for targeted immunotherapy of cancer.

Dual Drug Loaded, pH-Sensitive Metal-Organic Particles for Synergistic Cancer Therapy

The strategy for dual drug-loaded nanomedicine with targeting properties was always complex. Herein, a novel strategy for the preparation of metal-organic particle-based nanomedicine has been developed, and combretastatin A4 (CA4) and mitoxantrone (MIT) loaded MOPs (CMMOPs) have been obtained. In this system, using merely Cu(II) as a bridge to connect and coordinate with the dual drugs has resulted in the CMMOPs possessing a fairly high drug load of almost 90%. Moreover, the coordination between Cu(II) and the drugs was stable at physiological pH but easily cleavable in the tumor acidic microenvironment, which would provide a good targeting property for CMMOPs. The in vivo experiments indicated that CMMOPs possessed a significantly enhanced antitumor efficiency with negligible side effects. The results suggest that CMMOPs could be a potential anticancer formulation for tumor-targeted drug delivery.

Recent advances in porous nanomaterials-based drug delivery systems for cancer immunotherapy

Cancer immunotherapy is a novel therapeutic regimen because of the specificity and durability of immune modulations to treat cancers. Current cancer immunotherapy is limited by some barriers such as poor response rate, low tumor specificity and systemic toxicities. Porous nanomaterials (PNMs) possess high loading capacity and tunable porosity, receiving intense attention in cancer immunotherapy. Recently, novel PNMs based drug delivery systems have been employed in antitumor immunotherapy to enhance tissue or organ targeting and reduce immune-related adverse events. Herein, we summarize the recent progress of PNMs including inorganic, organic, and organic–inorganic hybrid ones for cancer immunotherapy. The design of PNMs and their performance in cancer immunotherapy are discussed in detail, with a focus on how those designs can address the challenges in current conventional immunotherapy. Lastly, we present future directions of PNMs for cancer immunotherapy including the challenges and research gaps, providing new insights about the design of PNMs for efficient cancer immunotherapy with better performance as powerful weapons against tumors. Finally, we discussed the relevant challenges that urgently need to be addressed in clinical practice, coupled with corresponding solutions to these problems.

Antibacterial Vancomycin@ZIF-8 Loaded PVA Nanofiber Membrane for Infected Bone Repair

Bone substitutes with strong antibacterial properties and bone regeneration effects have an inherent potential in the treatment of severe bone tissue infections, such as osteomyelitis. In this study, vancomycin (Van) was loaded into zeolitic imidazolate framework-8 (ZIF-8) to prepare composite particles, which is abbreviated as V@Z. As a pH-responsive particle, ZIF-8 can be cleaved in the weak acid environment caused by bacterial infection to realize the effective release of drugs. Then, V@Z was loaded into polyvinyl alcohol (PVA) fiber by electrospinning to prepare PVA/V@Z composite bone filler. The drug-loading rate of V@Z was about 6.735%. The membranes exhibited super hydrophilicity, water absorption and pH-controlled Van release behavior. The properties of anti E. coli and S. aureus were studied under the pH conditions of normal physiological tissues and infected tissues (pH 7.4 and pH 6.5, respectively). It was found that the material had good surface antibacterial adhesion and antibacterial property. The PVA/V@Z membrane had the more prominent bacteria-killing effect compared with the same amount of single antibacterial agent containing membrane such as ZIF-8 or Van loaded PVA, and the antibacterial rate was up to 99%. The electrospun membrane had good biocompatibility and can promote MC3T3-E1 cell spreading on it.

DNA-Mimicking Metal-Organic Frameworks with Accessible Adenine Faces for Complementary Base Pairing

Biologically derived metal-organic frameworks (Bio-MOFs) are significant, as they can be used in cutting-edge biomedical applications such as targeted gene delivery. Herein, adenine (Ade) and unnatural amino acids coordinate with Zn²⁺ to produce biocompatible frameworks, KBM-1 and KBM-2, with extremely defined porous channels. They feature an accessible Watson-Crick Ade face that is available for further hydrogen bonding and can load single-stranded DNA (ssDNA) with 13 and 41% efficiency for KBM-1 and KBM-2, respectively. Treatment of these frameworks with thymine (Thy), as a competitive guest for base pairing with the Ade open sites, led to more than 50% reduction of ssDNA loading. Moreover, KBM-2 loaded Thy-rich ssDNA more efficiently than Thy-free ssDNA. These findings support the role of the Thy-Ade base pairing in promoting ssDNA loading. Furthermore, theoretical calculations using the self-consistent charge density functional tight-binding (SCC-DFTB) method verified the role of hydrogen bonding and van der Waals type interactions in this host-guest interface. KBM-1 and KBM-2 can protect ssDNA from enzymatic degradation and release it at acidic pH. Most importantly, these biocompatible frameworks can efficiently deliver genetic cargo with retained activity to the cell nucleus. We envisage that this class of Bio-MOFs can find immediate applicability as biomimics for sensing, stabilizing, and delivering genetic materials.

An NIR Discrete Metallacycle Constructed from Perylene Bisimide and Tetraphenylethylene Fluorophores for Imaging-Guided Cancer Radio-Chemotherapy

To promote the clinical theranostic performances of platinum-based anticancer drugs, imaging capability is urgently desired, and their chemotherapeutic efficacy needs to be upgraded. Herein, a theranostic metallacycle (M) is developed for imaging-guided cancer radio-chemotherapy using perylene bisimide fluorophore (PPy) and tetraphenylethylene-based di-Pt(II) organometallic precursor (TPE-Pt) as building blocks. The formation of this discrete supramolecular coordination complex facilitates the encapsulation of M by a glutathione (GSH)-responsive amphiphilic block copolymer to prepare M-loaded nanoparticles (MNPs). TPE-Pt acts as a chemotherapeutic drug and also an excellent radiosensitizer, thus incorporating radiotherapy into the nanomedicine to accelerate the therapeutic efficacy and overcome drug resistance. The NIR-emission of PPy is employed to detect the intracellular delivery and tissue distribution of MNPs in real time. In vitro and in vivo investigations demonstrate the excellent anticancer efficacy combining chemotherapy and radiotherapy; the administration of this nanomedicine effectively inhibits the tumor growth and greatly extends the survival rate of cisplatin-resistant A2780CIS-tumor-bearing mice. Guided by in vivo fluorescence imaging, radio-chemotherapy is precisely carried out, which facilitates boosting of the therapeutic outcomes and minimizing undesired side effects. The success of this theranostic system brings new hope to supramolecular nanomedicines for their potential clinical translations.

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.

Metal-Organic Frameworks and Their Composites Towards Biomedical Applications

Owing to their unique features, including high cargo loading, biodegradability, and tailorability, metal–organic frameworks (MOFs) and their composites have attracted increasing attention in various fields. In this review, application strategies of MOFs and their composites in nanomedicine with emphasis on their functions are presented, from drug delivery, therapeutic agents for different diseases, and imaging contrast agents to sensor nanoreactors. Applications of MOF derivatives in nanomedicine are also introduced. Besides, we summarize different functionalities related to MOFs, which include targeting strategy, biomimetic modification, responsive moieties, and other functional decorations. Finally, challenges and prospects are highlighted about MOFs in future applications.

Adoptive T-cell Immunotherapy: Perfecting Self-Defenses

As an important part of the immune system, T lymphocytes exhibit undoubtedly an important role in targeting and eradicating cancer. However, despite these characteristics, their natural antitumor response may be insufficient. Numerous clinical trials in terminally ill cancer patients testing the design of novel and efficient immunotherapeutic approaches based on the adoptive transfer of autologous tumor-specific T lymphocytes have shown encouraging results. Moreover, this also led to the approval of engineered T-cell therapies in patients. Herein, we will expand on the development and the use of such strategies using tumor-infiltrating lymphocytes or genetically engineered T-cells. We will also comment on the requirements and potential hurdles encountered when elaborating and implementing such treatments as well as the exciting prospects for this kind of emerging personalized medicine therapy.

Biological luminescent metal-organic framework with high fluorescence quantum yield for the selective detection of amino acids and monosaccharides

The biological luminescent metal-organic framework (bio-LMOF), (Me2NH2)2[Zn6O(Ade)4(TCPPE)2] (1) {H4TCPPE = tetrakis[4-(4-carboxyphenyl)phenyl]ethene, Ade = adenine} was successfully designed and synthesized under hydrothermal condition, with two channels of different sizes. The absolute...

Preparation of hollow tubular TpBD COF and pod-like ZIF-8/H-TpBD COF tubes using a porous anodic aluminum oxide membrane as template

By sacrificing a porous anodic aluminum oxide (AAO) membrane as a template, hollow tubular TpBD (H-TpBD) covalent organic framework (COF) tubes were synthesized in situ and zeolitic imidazolate framework (ZIF-8) nanoparticles were creatively synthesized in situ in H-TpBD tubes at room temperature. H-TpBD COF tubes and ZIF-8/H-TpBD COF tubes were procured by using a strong base or acid to remove the AAO membrane. Then they were analyzed by X-ray diffraction, Fourier infrared spectroscopy, scanning electron microscope, transmission electron microscope, etc. Surprisingly, the obtained TpBD COF has a very small aperture (1.8 nm), thinner tube thickness (50 nm), high stability, and a smooth and homogeneous surface. And the pod-like ZIF-8/H-TpBD COF with complete tubular structure was also obtained.

By sacrificing porous anodic aluminum oxide (AAO) membrane, hollow tubular TpBD (H-TpBD) COF tubes were synthesized and zeolitic imidazolate framework (ZIF-8) nanoparticles were creatively synthesized in situ in H-TpBD tubes at room temperature.

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.

MOFs-based nanoagent enables dual mitochondrial damage in synergistic antitumor therapy via oxidative stress and calcium overload

Targeting subcellular organelle with multilevel damage has shown great promise for antitumor therapy. Here, we report a core-shell type of nanoagent with iron (III) carboxylate metal-organic frameworks (MOFs) as shell while upconversion nanoparticles (UCNPs) as core, which enables near-infrared (NIR) light-triggered synergistically reinforced oxidative stress and calcium overload to mitochondria. The folate decoration on MOFs shells enables efficient cellular uptake of nanoagents. Based on the upconversion ability of UCNPs, NIR light mediates Fe³⁺-to-Fe²⁺ reduction and simultaneously activates the photoacid generator (pHP) encapsulated in MOFs cavities, which enables release of free Fe²⁺ and acidification of intracellular microenvironment, respectively. The overexpressed H₂O₂ in mitochondria, highly reactive Fe²⁺ and acidic milieu synergistically reinforce Fenton reactions for producing lethal hydroxyl radicals (•OH) while plasma photoacidification inducing calcium influx, leading to mitochondria calcium overload. The dual-mitochondria-damage-based therapeutic potency of the nanoagent has been unequivocally confirmed in cell- and patient-derived tumor xenograft models in vivo.

Targeting damage to mitochondria has become an effective strategy antitumor therapies. Here, the authors report on nanoagents with upconversion nanoparticles as cores and photoacid-loaded MOFs as shells for NIR triggered Fenton reaction, acidification and calcium overload to provide synergistic mitochondrial damage.

The application of immune checkpoint blockade in breast cancer and the emerging role of nanoparticle

Breast cancer is the most common malignancy in the female population with a high mortality rate. Despite the satisfying depth of studies evaluating the contributory role of immune checkpoints in this malignancy, few articles have reviewed the pros and cons of immune checkpoint blockades (ICBs). In the current review, we provide an overview of immune-related inhibitory molecules and also discuss the original data obtained from international research laboratories on the aberrant expression of T and non-T cell-associated immune checkpoints in breast cancer. Then, we especially focus on recent studies that utilized ICBs as the treatment strategy in breast cancer and provide their efficiency reports. As there are always costs and benefits, we discuss the limitations and challenges toward ICB therapy such as adverse events and drug resistance. In the last section, we allocate an overview of the recent data concerning the application of nanoparticle systems for cancer immunotherapy and propose that nano-based ICB approaches may overcome the challenges related to ICB therapy in breast cancer. In conclusion, it seems it is time for nanoscience to more rapidly move forward into clinical trials and illuminates the breast cancer treatment area with its potent features for the target delivery of ICBs.

Localized delivery of immunotherapeutics: A rising trend in the field

Immunotherapy is becoming a new standard of care for multiple cancers, while several limitations are impending its further clinical success. Immunotherapeutic agents often have inappropriate pharmacokinetics on their own and/or exhibit limited specificity to tumor cells, leading to severe immuno-related adverse effects and limited efficacy. Suitable formulating strategies that confer prolonged contact with or efficient proliferation in tumors while reducing exposure to normal tissues are highly worthy to explore. With the assistance of biomaterial carriers, targeted therapy can be achieved artificially by implanting or injecting drug depots into desired sites, about which the wisdoms in literature have been rich. The relevant results have suggested a "local but systemic" effect, that is, local replenishment of immune modulators achieves a high treatment efficacy that also governs distant metastases, thereby building another rationale for localized delivery. Particularly, implantable scaffolds have been further engineered to recruit disseminated tumor cells with an efficiency high enough to reduce tumor burdens at typical metastatic organs, and simultaneously provide diagnostic signals. This review introduces recent advances in this emerging area along with a perspective on the opportunities and challenges in the way to clinical application.

Immunotherapy of tumors by tailored nano-zeolitic imidazolate framework protected biopharmaceuticals

In cancer immunotherapy, antibodies have acquired rapidly increasing attention due to their sustained immune effect by target specific delivery without any adverse effects. Among many recent strategies, controlled delivery of monoclonal antibodies, check point inhibitor storage and tumor-specific targeted delivery have enabled biodegradable immunotherapeutic delivery via translation of tailored nano-zeolitic imidazolate frameworks (ZIFs) with encapsulated biopharmaceuticals. In addition, a robust antitumor immunity was developed by anti-programmed death ligand-1 (anti-PD-L1) antibody delivery by ZIF-8 with polyethylene glycol (PEG) protection by forming a multiple immunoregulatory system. The unique biorecognition capability of antibodies, encapsulated in ZIFs, was recognized by using growth on different substrates, such as bioconjugates on gold nanorods, to transform them into plasmonic nanobiosensors with sensitivity of the refractive index profile of surface plasmons to track the conjugating antibody. Herein, we have discussed the mechanistic window of antibody delivery-based immunotherapy via the encapsulation of antibodies within ZIFs as an emerging tool for protecting biopharmaceuticals from the complex cellular microenvironment and hyperthermia to enable an antitumor immune response. To fully achieve the potential of antibodies upon ZIF encapsulation, more endeavors should be undertaken in the biodegradable engineering of ZIF-surfaces via forming cellular or polymeric layers to gain higher in vivo circulation time without inhibiting endocytosis by tumor cells. The possible future prognosis for achieving ZIF-protected biocompatible and biodegradable immunotherapeutic antibody delivery systems of therapeutic significance is discussed.

Pt Nanoparticles Anchored on NH2-MIL-101 with Efficient Peroxidase-Like Activity for Colorimetric Detection of Dopamine

Dopamine (DA) is an important catecholamine neurotransmitter that plays a highly relevant role in regulating the central nervous system, and abnormal DA content can cause many immune-related diseases. Hence, it is of significance to sensitively and specifically identify DA for clinical medicine. In this work, Pt/NH2-MIL-101 hybrid nanozymes with bimetallic catalytic centers were fabricated by forming coordinate bonds between Pt nanoparticles (Pt NPs) and –NH2 on metal–organic frameworks (MOF). The catalytic activity of Pt/NH2-MIL-101 was increased by 1.5 times via enlarging the exposure of more active sites and improving the activity of the active sites through the strategy of forming bimetallic catalytic centers. In the presence of DA, competing with 3, 3′, 5, 5′-tetramethylbenzidine (TMB) for the generated hydroxyl radicals (•OH), the blue oxidation state TMB (Ox-TMB) is reduced to colorless TMB, showing dramatic color changes. The Pt/NH2-MIL-101-based colorimetric assay enables the sensitive and robust detection of DA molecules with a detection limit of only 0.42 μM and has an observable potential in clinical applications.

Biocompatibility and biodegradability of metal organic frameworks for biomedical applications

Metal organic frameworks (MOFs) are a unique class of smart hybrid materials that have recently attracted significant interest for catalysis, separation and biomedical applications. Different strategies have been developed to overcome the limitations of MOFs for bio-applications in order to produce a system with high biocompatibility and biodegradability. In this review, we outline the chemical and physical factors that dictate the biocompatibility and biodegradability characteristics of MOFs including the nature of the metal ions and organic ligands, size, surface properties and colloidal stability. This review includes the in vitro biodegradation and in vivo biodistribution studies of MOFs to better understand their pharmacokinetics, organ toxicity and immune response. Such studies can guide the design of future bio-friendly systems that bring us closer to safely translating these platforms into the pharmaceutical consumer market.