Metal–Organic Framework-Assisted Nanoplatform with Hydrogen Peroxide/Glutathione Dual-Sensitive On-Demand Drug Release for Targeting Tumors and Their Microenvironment

Applications of Metal-Organic Frameworks (MOFs) in Drug Delivery, Biosensing, and Therapy: A Comprehensive Review

The porous materials known as metal-organic frameworks (MOFs) stand out for their enormous surface area, adaptable pore size and shape, and structural variety. These characteristics make them well-suited for various applications, especially in healthcare. This review thoroughly summarizes recent studies on the use of MOFs in drug delivery, biosensing, and therapeutics. MOFs may encapsulate medications, target certain cells or tissues, and regulate their release over time. Additionally, MOFs have the potential to be used in biosensing applications, allowing for the selective detection of chemical and biological substances. MOFs' optical or electrical characteristics may be modified to make biosensors that track physiological data. MOFs show potential for targeted drug delivery and the regulated release of therapeutic substances in cancer treatment. In addition, they may work as potent antibacterial agents, providing a less dangerous option than traditional antibiotics that increase antibiotic resistance. For practical applications, further research is required as well as more consideration for the problems with toxicity and biocompatibility. In addition to addressing the difficulties and promising possibilities in this area, this study intends to provide insights into the potential of MOFs in healthcare for drug delivery, biosensing, and treatment. Despite several essential reviews in this area, it was necessary to look into the most recent research on drug delivery, biosensing, and therapy as a combined concept.

Metal organic framework-based variable-size nanoparticles for tumor microenvironment-responsive drug delivery

Nanoparticles (NPs) have been designed for the treatment of tumors increasingly. However, the drawbacks of single-size NPs are still worth noting, as their circulation and metabolism in the blood are negatively correlated with their accumulation at the tumor site. If the size of single-size NPs is too small, it will be quickly cleared in the blood circulation, while, the size is too large, the distribution of NPs in the tumor site will be reduced, and the widespread distribution of NPs throughout the body will cause systemic toxicity. Therefore, a class of variable-size NPs with metal organic frameworks (MOFs) as the main carrier, and size conversion in compliance with the characteristics of the tumor microenvironment (TME), was designed. MOF-based variable-size NPs can simultaneously extend the time of blood circulation and metabolism, then enhance the targeting ability of the tumor site. In this review, MOF NPs are categorized and exemplified from a new perspective of NP size variation; the advantages, mechanisms, and significance of MOF-based variable-size NPs were summarized, and the potential and challenges in delivering anti-tumor drugs and multimodal combination therapy were discussed.

Recent Progress in Implantable Drug Delivery Systems

In recent years, tremendous effort is devoted to developing platforms, such as implantable drug delivery systems (IDDSs), with temporally and spatially controlled drug release capabilities and improved adherence. IDDSs have multiple advantages: i) the timing and location of drug delivery can be controlled by patients using specific stimuli (light, sound, electricity, magnetism, etc.). Some intelligent "closed-loop" IDDS can even realize self-management without human participation. ii) IDDSs enable continuous and stable delivery of drugs over a long period (months to years) and iii) to administer drugs directly to the lesion, thereby helping reduce dosage and side effects. iv) IDDSs enable personalized drug delivery according to patient needs. The high demand for such systems has prompted scientists to make efforts to develop intelligent IDDS. In this review, several common stimulus-responsive mechanisms including endogenous (e.g., pH, reactive oxygen species, proteins, etc.) and exogenous stimuli (e.g., light, sound, electricity, magnetism, etc.), are given in detail. Besides, several types of IDDS reported in recent years are reviewed, including various stimulus-responsive systems based on the above mechanisms, radio frequency-controlled IDDS, "closed-loop" IDDS, self-powered IDDS, etc. Finally, the advantages and disadvantages of various IDDS, bottleneck problems, and possible solutions are analyzed to provide directions for subsequent research.

Stimuli-Responsive Design of Metal-Organic Frameworks for Cancer Theranostics: Current Challenges and Future Perspective

Scientific fraternity revealed the potential of stimuli-responsive nanotherapeutics for cancer treatment that aids in tackling the major restrictions of traditionally reported drug delivery systems. Among stimuli-responsive inorganic nanomaterials, metal-organic frameworks (MOFs) have transpired as unique porous materials displaying resilient structures and diverse applications in cancer theranostics. Mainly, it demonstrates tailorable porosity, versatile chemical configuration, tunable size and shape, and feasible surface functionalization, etc. The present review provides insights into the design of stimuli-responsive multifunctional MOFs for targeted drug delivery and bioimaging for effective cancer therapy. Initially, the concept of cancer, traditional cancer treatment, background of MOFs, and approaches for MOFs synthesis have been discussed. After this, applications of stimuli-responsive multifunctional MOFs-assisted nanostructures that include pH, light, ions, temperature, magnetic, redox, ATP, and others for targeted drug delivery and bioimaging in cancer have been thoroughly discussed. As an outcome, the designed multifunctional MOFs showed an alteration in properties due to the exogenous and endogenous stimuli that are beneficial for drug release and bioimaging. The several reported types of stimuli-responsive surface-modified MOFs revealed good biocompatibility to normal cells, promising drug loading capability, target-specific delivery of anticancer drugs into cancerous cells, etc. Despite substantial progress in this field, certain crucial issues need to be addressed to reap the clinical benefits of multifunctional MOFs. Specifically, the toxicological compatibility and biodegradability of the building blocks of MOFs demand a thorough evaluation. Moreover, the investigation of sustainable and greener synthesis methods is of the utmost importance. Also, the low flexibility, off-target accumulation, and compromised pharmacokinetic profile of stimuli-responsive MOFs have attracted keen attention. In conclusion, the surface-modified nanosized design of inorganic diverse stimuli-sensitive MOFs demonstrated great potential for targeted drug delivery and bioimaging in different kinds of cancers. In the future, the preference for stimuli-triggered MOFs will open a new frontier for cancer theranostic applications.

Trend in biodegradable porous nanomaterials for anticancer drug delivery

In recent years, biodegradable nanomaterials have exhibited remarkable promise for drug administration to tumors due to their high drug-loading capacity, biocompatibility, biodegradability, and clearance. This review will discuss and summarize the trends in utilizing biodegradable nanomaterials for anticancer drug delivery, including biodegradable periodic mesoporous organosilicas (BPMOs) and metal-organic frameworks (MOFs). The distinct structure and features of BPMOs and MOFs will be initially evaluated, as well as their use as delivery vehicles for anticancer drug delivery applications. Then, the themes for the development of each material will be utilized to illustrate their drug delivery performance. Finally, the current obstacles and potential for future development as efficient drug delivery systems will be thoroughly reviewed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Core-shell structured hollow copper sulfide@metal-organic framework for magnetic resonance imaging guided photothermal therapy in second near-infrared biological window

Multifunctional core-shell hybrids formed by integration of metal-organic framework (MOF) and functional materials have attracted extensive attention as promising theranostic nanoplatforms due to their combined novel properties and enhanced therapeutic efficacy. Recently, the second near-infrared (NIR-II, 1000-1700 nm) laser-induced photothermal therapy (PTT) as compared to the NIR-I(700-950 nm) laser-induced PTT has displayed improved therapeutic effects owing to its merits that include deeper tissue penetration and increased maximum permissible exposure. Herein, a novel core-shell hollow copper sulfide@metal-organic framework (HCuS@MIL-100) has been successfully fabricated by a layer-by-layer technique for the first time and their collective theranostic effects are investigated in vitro and in vivo. In this platform, the inner HCuS was applied as the NIR-II photothermal agent with excellent NIR-II absorption feature, leading to impressive photothermal effects under irradiation by 1064 nm light. With MIL-100 as the shell, HCuS@MIL-100 not only displayed optimal biocompatibility but also presented superior T2 magnetic resonance imaging (MRI) ability. In the current study multifunctional hollow core-shell HCuS@MIL-100 are fabricated for the MRI-guided PTT. This study also offers a facile and effective strategy for the development of novel theranostic platforms with high efficiency through the integration of MOFs and functional materials.

Platinum-Coordinated Dual-Responsive Nanogels for Universal Drug Delivery and Combination Cancer Therapy

Developing a universal nanoplatform for efficient delivery of various drugs to target sites is urgent for overcoming various biological barriers and realizing combinational cancer treatment. Nanogels, with the advantages of both hydrogels and nanoparticles, may hold potential for addressing the above issue. Here, a dual-responsive nanogel platform (HPC nanogel) is constructed using β-cyclodextrin-conjugated hyaluronic acid (HA-βCD), polyethyleneimine (PEI), and cisplatin. HA-βCD and PEI compose the skeleton of the nanogel, and cisplatin molecules provide the junctions inside the skeleton, thus affording a multiple interactions-based nanogel. Besides, HA endows the nanogel with hyaluronidase (HAase)-responsiveness, and cisplatin guarantees the glutathione (GSH)-responsive ability, which make the nanogel a dual-responsive platform that can degrade and release the loaded drugs when encountering HAase or GSH. Additionally, the HPC nanogel possesses excellent small-molecule drug and protein loading and intracellular delivery capabilities. Especially, for proteins, their intracellular delivery via nanogels is not hindered by serum proteins, and the enzymes delivered into cells still maintain their catalytic activities. Furthermore, the nanogel can codeliver different cargoes to achieve "cocktail" chemotherapeutic efficacy and realize combination cancer therapy. Overall, the HPC nanogel can serve as a multifunctional platform capable of delivering desired drugs to treat cancer or other diseases.

Two Zn(II) coordination polymers with anticancer drug norcantharidin as ligands for cancer chemotherapy

Here two Zn(II) coordination polymers [Zn₂₀(DMCA)₁₂]O₁₂ (DMCA = demethylcantharic acid, DMCA-Zn1) and [Zn(DMCA)](H₂O)₂ (DMCA-Zn2) are synthesized from a broad-spectrum anticancer drug norcantharidin (NCTD) and Zn(NO₃)₂·6H₂O under solvothermal conditions. By mechanical grinding with a biocompatible polymeric surfactant F127, ultrasonic treatment and filtration, DMCA-Zn1 and DMCA-Zn2 can be transformed into stable nanoparticles (DMCA-Zn1 NPs and DMCA-Zn2 NPs) suspended in water with average diameters of around 190 nm and 162 nm for drug delivery. The in vitro evaluation indicates that DMCA-Zn1 NPs and DMCA-Zn2 NPs can enter into HepG2 and Hep3B cancer cells via endocytosis and inhibit their proliferation. Meanwhile they exhibit relatively low toxicity to L927 normal cells. The in vivo evaluation confirms that DMCA-Zn1 NPs and DMCA-Zn2 NPs can more effectively inhibit the growth of Hep3B tumors with relatively few side effects compared with free NCTD. This approach can be extended to other anticancer drugs to construct nanodrug delivery systems for cancer treatment.

New diagnostic and therapeutic strategies for myocardial infarction via nanomaterials

Myocardial infarction is lethal to patients because of insufficient blood perfusion to vital organs. Several attempts have been made to improve its prognosis, among which nanomaterial research offers an opportunity to address this problem at the molecular level and has the potential to improve disease prevention, diagnosis, and treatment significantly. Up to now, nanomaterial-based technology has played a crucial role in broad novel diagnostic and therapeutic strategies for cardiac repair. This review summarizes various nanomaterial applications in myocardial infarction from multiple aspects, including high precision detection, pro-angiogenesis, regulating immune homeostasis, and miRNA and stem cell delivery vehicles. We also propose promising research hotspots that have not been reported much yet, such as conjugating pro-angiogenetic elements with nanoparticles to construct drug carriers, developing nanodrugs targeting other immune cells except for macrophages in the infarcted myocardium or the remote region. Though most of those strategies are preclinical and lack clinical trials, there is tremendous potential for their further applications in the future.

Embedding an extraordinary amount of gemifloxacin antibiotic in ZIF-8 framework with one-step synthesis and measurement of its H2O2-sensitive release and potency against infectious bacteria

GEM@ZIF-8 has DLC = 69.82% and DLE = 89.03%, with controlled release dependent on H2O2 concentration, and it shows significant antibacterial activity.

Facile and single-step entrapment of chloramphenicol in ZIF-8 and evaluation of its performance in killing infectious bacteria with high loading content and controlled release of the drug

CLN@ZIF-8 was prepared by trapping chloramphenicol during ZIF-8 synthesis with high DLC and DLE. It showed H2O2-sensitive controlled release with higher drug release under the simulated infectious conditions and short-time antibacterial activity.

Use of pH-Active Catechol-Bearing Polymeric Nanogels with Glutathione-Responsive Dissociation to Codeliver Bortezomib and Doxorubicin for the Synergistic Therapy of Cancer

Synergistic therapy holds promising potential in cancer treatment. Here, the inclusion of catechol moieties, a disulfide cross-linked structure, and pendent carboxyl into the network of polymeric nanogels with glutathione (GSH)-responsive dissociation and pH-sensitive release is first disclosed for the codelivery of doxorubicin (DOX) and bortezomib (BTZ) in synergistic cancer therapy. The pendent carboxyl groups and catechol moieties are exploited to absorb DOX through electrostatic interaction and conjugate BTZ through boronate ester, respectively. Both electrostatic interactions and boronate ester are stable at neutral or alkaline pH, while they are instable in an acidic environment to further recover the activities of BTZ and DOX. The polymeric nanogels possess a superior stability to prevent the premature leakage of drugs in a physiological environment, while their structure is destroyed in response to a typical endogenous stimulus (GSH) to unload drugs. The dissociation of the drug-loaded nanogels accelerates the intracellular release of DOX and BTZ and further enhances the therapeutic efficacy. In vitro and in vivo investigations revealed that the dual-drug loaded polymeric nanogels exhibited a strong ability to suppress tumor growth. This study thus proposes a new perspective on the production of multifunctional polymeric nanogels through the introduction of different functional monomers.

Metallic Oxide-Induced Self-Assembly of Block Copolymers to Form Polymeric Hybrid Micelles with Tunable Stability for Tumor Microenvironment-Responsive Drug Delivery

Since block copolymers are able to self-assemble into various polymeric architectures, it is intriguing to explore a unique self-assembly strategy for polymers. Two different metallic oxides [manganese dioxide (MnO2) and zinc oxide (ZnO)] are displayed herein to demonstrate this self-assembly mechanism of polymers. In situ generation of metallic oxides induces self-assembly of block copolymers to form polymeric hybrid micelles with tunable stability in aqueous solutions. These final ZnO-cross-linked polymeric micelles exhibited a high drug loading capacity of 0.41 mg mg-1 toward doxorubicin (DOX), whereas DOX-loaded ZnO-cross-linked polymeric micelles could be broken down into Zn2+ and polymer scraps, which facilitated drug release in tumor microenvironments. Both in vitro and in vivo investigations showed that the drug-loaded ZnO-cross-linked polymeric micelles effectively suppressed tumor growth. Accordingly, the present study demonstrates a novel strategy of polymer self-assembly for fabricating polymeric architectures that can potentially provide insight for developing other polymeric architectures.

Optimized mesoporous silica nanoparticle-based drug delivery system with removable manganese oxide gatekeeper for controlled delivery of doxorubicin

Rapid progress has been made for mesoporous silica nanoparticle (MSN) in recent years; however, efforts to fabricate MSN with adjustable size have been met with limited advancement in drug delivery, especially for the synthesis of MSN with adjustable size in the range of 150-300 nm. Herein we report the construction of a series of MSNs with adjustable specific surface area, size, and pore structure, depending on the different silicon monomers selected. The optimized MSN showed large specific surface area and appropriate size distribution for efficiently anchoring doxorubicin (DOX) through the imine linkage formed. Based on the remarkable features of the unique MSN, a novel MSN-based drug delivery system was prepared through the introduction of polydopamine/manganese oxide (PDA/MnO₂) coating, which reduced the premature leakage of drugs in physiological environments, and yet facilitated drug release when destroyed by responding to endogenous glutathione (GSH) at the tumor sites. Notably, the transformation of MnO₂ to Mn²⁺ resulted in the collapse of the PDA/MnO₂ coating, which facilitated drug release and therefore indicated the controlled release feature. It was demonstrated that the drug-loaded MSN-based drug delivery system delivered drugs into cancer cells and showed effective inhibition against cancer cell growth. These results suggested that the emergence of MSN with adjustable size can expand the application of MSN in drug delivery.

Stimuli-responsive metal-organic framework nanoparticles for controlled drug delivery and medical applications

Stimuli-responsive metal-organic framework nanoparticles, NMOFs, provide a versatile platform for the controlled release of drugs and biomedical applications. The porous structure of NMOFs, their biocompatibility, low toxicity, and efficient permeability turn the NMOFs into ideal carriers for therapeutic applications. Two general methods to gate the drug-loaded NMOFs and to release the loads were developed: by one method, the loaded NMOFs are coated or surface-modified with stimuli-responsive gates being unlocked in the presence of appropriate chemical (e.g., ions or reducing agents), physical (e.g., light or heat), or biomarker (e.g., miRNA or ATP) triggers. By a second approach, the drug-loaded NMOFs include encoded structural information or co-added agents to induce the structural distortion or stimulate the degradation of the NMOFs. Different chemical triggers such as pH changes, ions, ATP, or redox agents, and physical stimuli such as light or heat are applied to degrade the NMOFs, resulting in the release of the loads. In addition, enzymes, DNAzymes, and disease-specific biomarkers are used to unlock the gated NMOFs. The triggered release of drugs for cancer therapy, anti-blood clotting, and the design of autonomous insulin-delivery systems ("artificial pancreas") are discussed. Specifically, multi-drug carrier systems and functional NMOFs exhibiting dual and cooperative therapeutic functions are introduced. The future perspectives and applications of stimuli-responsive particles are addressed.

Recent advances in nanosized metal organic frameworks for drug delivery and tumor therapy

Metal organic-frameworks (MOFs) are novel materials that have attracted increasing attention for applications in a wide range of research, owing to their unique advantages including their small particle size, porous framework structure and high specific surface area. Because of their adjustable size, nanoscale MOFs (nano-MOFs) can be prepared as carriers of biotherapy drugs, thus enabling biotherapeutic applications. Nano-MOFs' metal ion catalytic activity and organic group functional characteristics can be exploited in biological treatments. Furthermore, the applications of nano-MOFs can be broadened by hybridization with other materials to form composites. This review focuses on the preparation and recent advances in nano-MOFs as drug carriers, therapeutic materials and functionalized materials in drug delivery and tumor therapy based on the single/multiple stimulus response of drug release to achieve the targeted therapy, offering a comprehensive reference for drug carrier design. At the end, the current challenges and prospects are discussed to provide significant insight into the design and applications of nano-MOFs in drug delivery and tumor therapy.

Smart metal organic frameworks: focus on cancer treatment

Metal–organic frameworks (MOFs), as a prominent category of hybrid porous materials, have been broadly employed as controlled systems of drug delivery due to their inherent interesting properties.

Polymerization of dopamine accompanying its coupling to induce self-assembly of block copolymer and application in drug delivery

The polymerization of dopamine and its coupling occur in succession, which synergistically induces the self-assembly of block copolymer to yield ordered structures, including micelles and vesicles.

One-pot synthesis of bimetallic metal–organic frameworks (MOFs) as acid–base bifunctional catalysts for tandem reaction

Bimetallic MIL-101(Al/Fe)–NH₂ exhibits enhanced acid–base bifunctional catalytic activity due to its synergistic mechanism and hierarchical pore system.

Enzyme-responsive polymeric micelles with fluorescence fabricated through aggregation-induced copolymer self-assembly for anticancer drug delivery

The TPE moiety with AIE is employed as functional hydrophobic chain to induce copolymer self-assembly and form polymeric micelle that can show enzyme-responsive drug delivery.

Recent Advances in Glucose-Oxidase-Based Nanocomposites for Tumor Therapy

Glucose oxidase (GOx) can react with intracellular glucose and oxygen (O₂ ) to produce hydrogen peroxide (H₂ O₂ ) and gluconic acid, which can cut off the nutrition source of cancer cells and consequently inhibit their proliferation. Therefore, GOx is recognised as an ideal endogenous oxido-reductase for cancer starvation therapy. This process can further regulate the tumor microenvironment by increasing the hypoxia and the acidity. Thus, GOx offers new possibilities for the elaborate design of multifunctional nanocomposites for tumor therapy. However, natural GOx is expensive to prepare and purify and exhibits immunogenicity, short in vivo half-life, and systemic toxicity. Furthermore, GOx is highly prone to degrade after exposure to biological conditions. These intrinsic shortcomings will undoubtedly limit its biomedical applications. Accordingly, some nanocarriers can be used to protect GOx from the surrounding environment, thus controlling or preserving the activity. A variety of nanocarriers including hollow mesoporous silica nanoparticles, metal-organic frameworks, organic polymers, and magnetic nanoparticles are summarized for the construction of GOx-based nanocomposites for multimodal synergistic cancer therapy. In addition, current challenges and promising developments in this area are highlighted.

Stimuli-responsive supramolecular nano-systems based on pillar[n]arenes and their related applications

Stimuli-responsive supramolecular nano-systems (SRNS) have been a trending interdisciplinary research area due to the responsiveness upon appropriate stimuli, which makes SRNS very attractive in multiple fields where precise control is vital.