A review of recent developments of metal-organic frameworks as combined biomedical platforms over the past decade

β-MnO2 nanozyme/Ni2+ mediated formation of TriOPD-Ni2+ polymers for specific and background-free detection of carbaryl

A novel photothermal sensing platform for direct, specific, and background-free detection of carbaryl has been fabricated. Firstly, β-MnO2 with excellent oxidase-like property has been screened out from MnO2 with different crystalline structures. Interestingly, Ni2+ as a chelator with nitrogen atom can modulate the MnO2 catalytic oxidation and assembly of o-phenylenediamine (OPD) to photothermal probe, OPD trimer (triOPD)-Ni2+ polymers, with an excellent photothermal conversion efficiency of 42.4 % under 808 nm laser irradiation. Then, carbaryl was hydrolyzed into reductive 1-naphthol in alkaline condition, which directly decomposed β-MnO2 into Mn2+ and significantly hindered the β-MnO2/Ni2+-mediated production of triOPD-Ni2+ polymers. Consequently, the photothermal effect was linearly correlated with carbaryl concentration in the range of 0.05-4.0 μM with a satisfactory limit of detection at 0.018 μM. Moreover, background-free detection of carbaryl can be achieved in actual food samples with good recovery (96.5%-104.3%), low relative standard deviation (≤1.0%), and excellent anti-interference capacity. The established photothermal sensor will not only provide an efficient method for carbaryl assay but also supply a new pathway for detection pesticides.

Boosting the Sustained Release Performance of Metronidazole and Ornidazole with MIL-53(Fe) Derived Spherical Porous Carbon

Metal-organic framework (MOF) derived spherical porous carbon (SPC) has potential application value in the field of adsorption and sustained release of nitroimidazole drugs. This work used MIL-53(Fe) as a precursor and prepared spherical 3-aminophenol-formaldehyde resin containing MIL-53(Fe) crystals using the advanced Stöber method, followed by the successful preparation of MIL-53(Fe) derived SPC (MSPC) with a structure containing both micropores and mesopores through high-temperature carbonization. The effects of the doping amount of MIL-53(Fe) on the sphericity and particle size of MSPC were investigated. The drug uptake capacity and sustained release performances of MSPC for metronidazole (MNZ) and ornidazole (ONZ) were assessed through batch tests, along with an investigation into the impact of varying pH levels on the sustained release performances. The experimental findings revealed that the drug loading of MNZ and ONZ onto MSPC achieved 111 and 120 mg/g, respectively, with a sustained release time of up to 24 h. The drug loading process adhered to the Langmuir isotherm adsorption model and conformed to the pseudo-second-order kinetics model, whereas the sustained release mechanism was consistent with the Korsmeyer-Peppas model. Furthermore, cytotoxicity and cyclic drug loading experiments indicated that MSPC exhibited good biocompatibility and stability. Therefore, this study provides new ideas for the development of SPC drug carriers.

Gold nanoparticle encapsulated hybrid MOF: synthesis, characterization, and co-drug delivery of 5-fluorouracil and curcumin

The unique features of Metal-Organic Frameworks (MOFs), including structural flexibility, high surface area, and variable pore size, have drawn attention in cancer therapy. However, despite advances in surface functionalization, engineering structural features, and porosity, achieving controlled release, stability, scalability, and toxicity remains a challenge. The current study reports gold nanoparticle (AuNP) encapsulated dual metal-organic frameworks (MOFs) comprising zeolitic imidazolate (ZIF8) and cobalt-imidazole (ZIF67) by a simple precipitation method for dual drug delivery applications. This combination associates the advantages of AuNPs and MOFs, creating a potent platform for cancer theranostics that combines diagnosis and treatment into one unit. The synthesized composite (AuNPs@ZIF-8/ZIF-67) is functionalized with Folic acid (FA) and loaded with the anticancer agents Curcumin (C) and 5-fluorouracil (5-FU) for co-drug delivery The synthesized composites, namely Au/ZIF8, Au/ZIF8/ZIF67/FA, Au/ZIF8/ZIF67/FA/5-FU, and Au/ZIF8/ZIF67/FA/5-FU/C were characterized using diverse analytical techniques such as FESEM, XRD, FTIR, TEM, and BET. The characterization methods showed that the hybrid MOF structure was stable and intact after AuNP encapsulation and drug loading. The dual MOF composite exhibits a better affinity for loading C and 5-FU with 60% and 40% drug loading capacity, respectively. The simultaneous drug release studies suggest that AuNPs@ZIF-8/ZIF-67 are more responsive to the acidic pH and show a higher cumulative drug release of 5FU and C at the lower value of pH 5. For further validation, the release kinetics data were fitted into the Korsmeyer-Peppas model in the current study. The observed value of n which is less than 0.5 suggests the pseudo-Fickian diffusion mechanism for drug release, demonstrating long-term release of 5FU and C from Au/ZIF8/ZIF67/FA/5-FU/C. The targeted drug delivery system is anticipated to display synergistic therapeutic efficacy from the combined effect of the two anticancer agents and the pH-responsive nature of ZIF systems.

A cocatalytic nanozyme based on metal-organic framework-embedded iron porphyrin for the sensitive detection of Salmonella typhimurium in milk

The nanozyme, acting as the signal labeling reporter, is widely employed in colorimetric immunoassays due to its exceptional catalytic activity and reliable performance. Nonetheless, when immobilized on the nanozyme's surface, there is a decline in catalytic activity, which hinders its ability to meet the escalating demand for advanced colorimetric immunoassays. Herein, we introduce a novel MILL-88@TcP nanozyme, formed by encapsulating iron porphyrins (TcP) within metal-organic frameworks (MILL-88), where the catalytic activity of TcP is fully preserved through ethanol-induced release. Leveraging the superior encapsulation capacity and enzyme-mimicking characteristics of MILL-88, the MILL-88@TcP nanozyme demonstrates a remarkable colorimetric performance, 1430-fold higher than that of MILL-88 alone. Furthermore, we developed the MILL-88@TcP nanozyme-based Enzyme-Linked Immunosorbent Assay (N-ELISA) for enhanced sensitivity in detecting Salmonella typhimurium, achieving a detection limit of 1.68 × 102 CFU/mL, approximately 500-fold enhancement compared to the traditional HRP-based ELISA (8.35 × 104 CFU/mL). Notably, the average recoveries ranged from 91.50 % to 108.50 % with a variation of 3.53 %-10.41 %, indicating high accuracy and precision. Collectively, this study highlights that the MILL-88@TcP nanozyme, with its superior catalytic performance and anti-interference capabilities, holds promise as a colorimetric labeling reporter to enhance the detection efficacy of colorimetric immunoassays and has the potential to establish a more stable and sensitive colorimetric assay platform.

Hyaluronic acid modified prussian blue analogs/TiO₂ janus nanostructures through efficient charge separation to enhance photocatalytic-driven dual gas for achieve multimodal treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by the abnormal proliferation of fibroblast-like synoviocytes and changes in the joint synovium, including elevated reactive oxygen species, decreased pH, and reduced oxygen content. In this study, we synthesized a novel nanocomposite material, namely HA-PBA-TiO2 Janus nanocomposite, by in situ etching in prussian blue analogs doped with Co and Ni, followed by the growth of TiO2 nano-flowers and encapsulation in hyaluronic acid. When these janus nanoparticles diffused to the inflammatory sites of RA, they exhibited outstanding photocatalytic water-splitting ability under 660 nm laser irradiation, generating H2 and O2. This capability helps ameliorate the hypoxic microenvironment at RA inflammatory sites by eliminating reactive oxygen species (ROS) and enhancing antioxidation and oxygenation. Furthermore, owing to the doping of Co and Ni, HA-PBA-TiO2 exhibits photothermal conversion capability, which significant damage to FLS upon exposure to 660 nm laser irradiation, thereby controlling their aberrant proliferation. Through a series of in vitro and in vivo experiments, we validated the significant therapeutic efficacy of HA-PBA-TiO2 in treating RA, highlighting its broad prospects for application.

Integrated design and application of stimuli-responsive metal-organic frameworks in biomedicine: current status and future perspectives

In recent years, metal-organic frameworks (MOFs) have garnered widespread attention due to their distinctive attributes, such as high surface area, tunable properties, biodegradability, extremely low density, high loading capacity, diverse chemical functionalities, thermal stability, well-defined pore sizes, and molecular dimensions. Increasingly, biomedical researchers have turned their focus towards their multifaceted development. Among these, stimuli-responsive MOFs, with their unique advantages, have captured greater interest from researchers. This review will delve into the merits and drawbacks of both endogenous and exogenous stimuli-responsive MOFs, along with their application directions. Furthermore, it will outline the characteristics of different synthesis routes of MOFs, exploring various design schemes and modification strategies and their impacts on the properties of MOF products, as well as how to control them. Additionally, we will survey different types of stimuli-responsive MOFs, discussing the significance of various MOF products reported in biomedical applications. We will categorically summarize different strategies such as anticancer therapy, antibacterial treatment, tissue repair, and biomedical imaging, as well as insights into the development of novel MOFs nanomaterials in the future. Finally, this review will conclude by summarizing the challenges in the development of stimuli-responsive MOFs in the field of biomedicine and providing prospects for future research endeavors.

Slowing Down the "Magic Bullet": Encapsulation of Imatinib in Fe-MOF for Cardiotoxicity Reduction and Improvement in Anticancer Activity

Imatinib, a small molecule kinase inhibitor, is used as a cancer growth blocker. However, one of its most serious side effects is congestive cardiac failure. Reducing drug toxicity may be achieved through the use of drug delivery systems. Biocompatible metal-organic framework (MOF) materials, namely FeMIL-100 and FeMIL-101-NH2, were employed as potential imatinib carriers. They efficiently delivered the drug as an anticancer agent while minimizing cardiotoxicity. Notably, the release of imatinib from FeMIL-100 was rapid in acidic conditions and slower in pH-neutral environments, allowing targeted delivery to cancer cells. The carrier's pH-dependent stability governed the drug release mechanism. Two release models-Korsmeyer-Peppas and Weibull-were fitted to the experimental data and discussed in terms of drug release from a rigid microporous matrix. Cytotoxicity tests were conducted on two cell lines: HL60 (a model cell line for acute myeloid leukemia) and H9c2 (a cell line for cardiomyocytes). Overall, the metal-organic framework (MOF) carriers mitigated imatinib's adverse effects without compromising its effectiveness.

Design and development of pH-responsive levofloxacin-loaded metal-organic framework for the promising treatment of pediatric abdominal wound repair

With over 9 million fatalities per year expected by 2030, infectious diseases will remain a significant burden on the world economy and cause high mortality rates. An excellent method to increase the bioactivity of levofloxacin (LEV) in pediatric abdominal wound repair is the finding of a stimuli-based drug delivery system (DDS). We designed and developed an LEV incorporated with zeolite imidazole framework-8 (ZIF-8) as a promising nanocarrier for wound healing applications. The spectral analysis and morphological analysis confirm the formation of our newly fabricated composites. Mouse embryonic fibroblast NIH3T3 cells, the cytotoxicity, cytocompatibility, and cell proliferation characteristics of LEV@ZIF-8 were evaluated in vitro. LEV@ZIF-8 composite considerably improved the biocompatibility against NIH3T3 cells after 72-h of exposure, according to in vitro experiments. Under acidic circumstances, the pH-responsive drug release studies exhibit superior LEV release, and in physiological circumstances, there is no unintended drug release. The LEV@ZIF-8 composite-treated cells demonstrate the most remarkable cell growth and migration method in a very short time, according to the results of the wound scratch experiment. The composite exposure concentration depended on inhibition against various microorganisms in the antibacterial activity testing. According to the study, LEV@ZIF-8 are appropriate and effective DDS for stimuli-based pediatric abdominal wound repair.

Metal-organic framework-based adsorbents for blood purification: progress, challenges, and prospects

Blood purification, such as hemodialysis (HD), plasma exchange (PE), and hemoperfusion (HP), is widely applied in patients with organ failure (such as kidney and liver failure). Among them, HP mainly relies on porous adsorbents to efficiently adsorb accumulated metabolic wastes and toxins, thus improving purification efficiency. Metal-organic frameworks (MOFs), with a high porosity, large surface area, high loading capacity, and tailorable topology, are emerging as some of the most promising materials for HP. Compared with non-metal framework counterparts, the self-built metal centers of MOFs feature the intrinsic advantages of coordination with toxin molecules. However, research on MOFs in blood purification is insufficient, particularly in contrast to materials applied in other biomedical applications. Thus, to broaden this area, this review first discusses the essential characteristics, potential mechanisms, and structure-function relationship between MOFs and toxin adsorption based on porosity, topology, ligand functionalization, metal centers, and toxin types. Moreover, the stability, utilization safety, and hemocompatibility of MOFs are illustrated for adsorbent selection. The current development and progress in MOF composites for HD, HP, and extracorporeal membrane oxygenation (ECMO) are also summarized to highlight their practicability. Finally, we propose future opportunities and challenges from materials design and manufacture to the computational prediction of MOFs in blood purification. It is anticipated that our review will expand the interest of researchers for more impact in this area.

Pore engineering of micro/mesoporous nanomaterials for encapsulation, controlled release and variegated applications of essential oils

Essential oils have become increasingly popular in fields of medical, food and agriculture, owing to their strongly antimicrobial, anti-inflammation and antioxidant effects, greatly meeting demand from consumers for healthy and safe natural products. However, the easy volatility and/or chemical instability of active ingredients of essential oils (EAIs) can result in the loss of activity before realizing their functions, which have greatly hindered the widely applications of EAIs. As an emerging trend, micro/mesoporous nanomaterials (MNs) have drawn great attention for encapsulation and controlled release of EAIs, owing to their tunable pore structural characteristics. In this review, we briefly discuss the recent advances of MNs that widely used in the controlled release of EAIs, including zeolites, metal-organic frameworks (MOFs), mesoporous silica nanomaterials (MSNs), and provide a comprehensive summary focusing on the pore engineering strategies of MNs that affect their controlled-release or triggered-release for EAIs, including tailorable pore structure properties (e.g., pore size, pore surface area, pore volume, pore geometry, and framework compositions) and surface properties (surface modification and surface functionalization). Finally, the variegated applications and potential challenges are also given for MNs based delivery strategies for EAIs in the fields of healthcare, food and agriculture. These will provide considerable instructions for the rational design of MNs for controlled release of EAIs.

Recent Advances of Emerging Metal-Containing Two-Dimensional Nanomaterials in Tumor Theranostics

In recent years, metal-containing two-dimensional (2D) nanomaterials, among various 2D nanomaterials have attracted widespread attention because of their unique physical and chemical properties, especially in the fields of biomedical applications. Firstly, the review provides a brief introduction to two types of metal-containing 2D nanomaterials, based on whether metal species take up the major skeleton of the 2D nanomaterials. After this, the synthetical approaches are summarized, focusing on two strategies similar to other 2D nanomaterials, top-down and bottom-up methods. Then, the performance and evaluation of these 2D nanomaterials when applied to cancer therapy are discussed in detail. The specificity of metal-containing 2D nanomaterials in physics and optics makes them capable of killing cancer cells in a variety of ways, such as photodynamic therapy, photothermal therapy, sonodynamic therapy, chemodynamic therapy and so on. Besides, the integrated platform of diagnosis and treatment and the clinical translatability through metal-containing 2D nanomaterials is also introduced in this review. In the summary and perspective section, advanced rational design, challenges and promising clinical contributions to cancer therapy of these emerging metal-containing 2D nanomaterials are discussed.

Light-driven micro/nanomotors in biomedical applications

Nanotechnology brings hope for targeted drug delivery. However, most current drug delivery systems use passive delivery strategies with limited therapeutic efficiency. Over the past two decades, research on micro/nanomotors (MNMs) has flourished in the biomedical field. Compared with other driven methods, light-driven MNMs have the advantages of being reversible, simple to control, clean, and efficient. Under light irradiation, the MNMs can overcome several barriers in the body and show great potential in the treatment of various diseases, such as tumors, and gastrointestinal, cardiovascular and cerebrovascular diseases. Herein, the classification and mechanism of light-driven MNMs are introduced briefly. Subsequently, the applications of light-driven MNMs in overcoming physiological and pathological barriers in the past five years are highlighted. Finally, the future prospects and challenges of light-driven MNMs are discussed as well. This review will provide inspiration and direction for light-driven MNMs to overcome biological barriers in vivo and promote the clinical application of light-driven MNMs in the biomedical field.

Gallium-based metal-organic frameworks loaded with antimicrobial peptides for synergistic killing of drug-resistant bacteria

Increased antibiotic resistance has made bacterial infections a global concern, which requires novel non-antibiotic-dependent antibacterial strategies to address the menace. Antimicrobial peptides (AMPs) are a promising antibiotic alternative, whose antibacterial mechanism is mainly to destroy the membrane of bacteria. Gallium ions exhibit an antibacterial effect by interfering with the iron metabolism of bacteria. With the rapid development of nanotechnology, it is worth studying the potential of gallium-AMP-based nanocomposites for treating bacterial infections. Herein, novel gallium-based metal-organic frameworks (MOFs) were synthesized at room temperature, followed by in situ loading of the model AMP melittin. The obtained nanocomposites exhibited stronger antibacterial activity than pure MEL and gallium ions, achieving the effects of "one plus one is greater than two". Moreover, the nanocomposites showed favorable biocompatibility and accelerated healing of a wound infected by methicillin-resistant Staphylococcus aureus by down-regulation of inflammatory cytokines IL-6 and TNF-α. This work presents an innovative antibacterial strategy to overcome the antibiotic resistance crisis and expand the application of AMPs.

Tunable metal-organic frameworks assist in catalyzing DNAzymes with amplification platforms for biomedical applications

Various binding modes of tunable metal organic frameworks (MOFs) and functional DNAzymes (Dzs) synergistically catalyze the emergence of abundant functional nanoplatforms. Given their serial variability in formation, structural designability, and functional controllability, Dzs@MOFs tend to be excellent building blocks for the precise "intelligent" manufacture of functional materials. To present a clear outline of this new field, this review systematically summarizes the progress of Dz integration into MOFs (MOFs@Dzs) through different methods, including various surface infiltration, pore encapsulation, covalent binding, and biomimetic mineralization methods. Atomic-level and time-resolved catalytic mechanisms for biosensing and imaging are made possible by the complex interplay of the distinct molecular structure of Dzs@MOF, conformational flexibility, and dynamic regulation of metal ions. Exploiting the precision of DNAzymes, MOFs@Dzs constructed a combined nanotherapy platform to guide intracellular drug synthesis, photodynamic therapy, catalytic therapy, and immunotherapy to enhance gene therapy in different ways, solving the problems of intracellular delivery inefficiency and insufficient supply of cofactors. MOFs@Dzs nanostructures have become excellent candidates for biosensing, bioimaging, amplification delivery, and targeted cancer gene therapy while emphasizing major advancements and seminal endeavors in the fields of biosensing (nucleic acid, protein, enzyme activity, small molecules, and cancer cells), biological imaging, and targeted cancer gene delivery and gene therapy. Overall, based on the results demonstrated to date, we discuss the challenges that the emerging MOFs@Dzs might encounter in practical future applications and briefly look forward to their bright prospects in other fields.

MOFs as Versatile Catalysts: Synthesis Strategies and Applications in Value-Added Compound Production

Catalysts played a crucial role in advancing modern human civilization, from ancient times to the industrial revolution. Due to high cost and limited availability of traditional catalysts, there is a need to develop cost-effective, high-activity, and nonprecious metal-based electrocatalysts. Metal-organic frameworks (MOFs) have emerged as an ideal candidate for heterogeneous catalysis due to their physicochemical properties, hybrid inorganic/organic structures, uncoordinated metal sites, and accessible organic sections. MOFs are high nanoporous crystalline materials that can be used as catalysts to facilitate polymerization reactions. Their chemical and structural diversity make them effective for various reactions compared to traditional catalysts. MOFs have been applied in gas storage and separation, ion-exchange, drug delivery, luminescence, sensing, nanofilters, water purification, and catalysis. The review focuses on MOF-enabled heterogeneous catalysis for value-added compound production, including alcohol oxidation, olefin oligomerization, and polymerization reactions. MOFs offer tunable porosity, high spatial density, and single-crystal XRD control over catalyst properties. In this review, MOFs were focused on reactions of CO2 fixation, CO2 reduction, and photoelectrochemical water splitting. Overall, MOFs have great potential as versatile catalysts for diverse applications in the future.

Functional Materials for Subcellular Targeting Strategies in Cancer Therapy: Progress and Prospects

Neoadjuvant and adjuvant therapies have made significant progress in cancer treatment. However, tumor adjuvant therapy still faces challenges due to the intrinsic heterogeneity of cancer, genomic instability, and the formation of an immunosuppressive tumor microenvironment. Functional materials possess unique biological properties such as long circulation times, tumor-specific targeting, and immunomodulation. The combination of functional materials with natural substances and nanotechnology has led to the development of smart biomaterials with multiple functions, high biocompatibilities, and negligible immunogenicities, which can be used for precise cancer treatment. Recently, subcellular structure-targeting functional materials have received particular attention in various biomedical applications including the diagnosis, sensing, and imaging of tumors and drug delivery. Subcellular organelle-targeting materials can precisely accumulate therapeutic agents in organelles, considerably reduce the threshold dosages of therapeutic agents, and minimize drug-related side effects. This review provides a systematic and comprehensive overview of the research progress in subcellular organelle-targeted cancer therapy based on functional nanomaterials. Moreover, it explains the challenges and prospects of subcellular organelle-targeting functional materials in precision oncology. The review will serve as an excellent cutting-edge guide for researchers in the field of subcellular organelle-targeted cancer therapy.

Functional MOF-Based Materials for Environmental and Biomedical Applications: A Critical Review

Over the last ten years, there has been a growing interest in metal-organic frameworks (MOFs), which are a unique category of porous materials that combine organic and inorganic components. MOFs have garnered significant attention due to their highly favorable characteristics, such as environmentally friendly nature, enhanced surface area and pore volume, hierarchical arrangements, and adjustable properties, as well as their versatile applications in fields such as chemical engineering, materials science, and the environmental and biomedical sectors. This article centers on examining the advancements in using MOFs for environmental remediation purposes. Additionally, it discusses the latest developments in employing MOFs as potential tools for disease diagnosis and drug delivery across various ailments, including cancer, diabetes, neurological disorders, and ocular diseases. Firstly, a concise overview of MOF evolution and the synthetic techniques employed for creating MOFs are provided, presenting their advantages and limitations. Subsequently, the challenges, potential avenues, and perspectives for future advancements in the utilization of MOFs in the respective application domains are addressed. Lastly, a comprehensive comparison of the materials presently employed in these applications is conducted.