Magnesium-gallate MOF integrated conductive cryogel for inflammation regulation and boosting bone regeneration

The regeneration and repair of natural bone is a complex and multifaceted process. Potentially, multifunctional scaffolds that exhibit synergistic effects of various biological activities and align with the dynamic bone healing process, are highly expected to achieve desirable bone repairing outcomes. Bioavailable magnesium (Mg) is an essential element taking part in bone regeneration via promoting angiogenesis and osteogenesis. Polyphenol gallic acid (GA) is an anti-inflammatory molecule that can modulate immune microenvironment. To control their release behaviors, Mg2+ and GA can react with each other to form metal-organic frameworks (MOF), which are then embedded into conductive porous scaffolds made of gelatin cryogel and poly(3,4-ethyldioxyethiophene): polystyrene sulfonate (PEDOT:PSS). In in vitro cell culture, the MOF-integrated conductive scaffold can simultaneously provide sustained supply of Mg2+ and GA to modulate the biological responses of a variety of cells. In in vivo evaluations, it shows remarkably enhanced new bone formation, as compared to groups of only MOF-contained non-conductive scaffold or conductive scaffold without MOF in rat calvarial defect model. In summary, conductive scaffold associated with sustained release of bioactive factors can serve as an effective treatment for inducing neo-bone growth benefiting from the synergistical contributions of diverse bioactive factors.

A nickel glutamate metal biomolecule framework

This paper describes the synthesis of a MbioF (Metal-biomolecule Framework) using glutamic acid and nickel carbonate as precursors. The direct action of glutamic acid (H2Glu) on basic nickel carbonate (NiCO3·2Ni(OH)2·4H2O) initially indicated the formation of a complex, [Ni(HGlu)2], which was then treated in a Teflon-lined stainless steel autoclave at 100 °C for 24 hours, resulting in the compound {[Ni(Glu)(H2O)]·H2O}n, with a yield of 43%. The resolution of the structure of this compound by single-crystal X-ray diffraction indicated that it belongs to the orthorhombic crystal system and space group P212121, with a structure analogous to those of the compounds {[Co(Glu)(H2O)]·H2O}n, {[Cu(Glu)(H2O)]·H2O}n and {[Zn(Glu)(H2O])·H2O}n described in the literature, with a molecular formula of C5H9NO5Ni·H2O, molar mass of 239.8379 g mol-1, parameters a, b and c with values of 7.0577(2) (Å), 10.2307(3) (Å) and 11.5350(4) (Å), and a volume of 837.219 Å3. This compound, which is an intensely green crystalline solid, was characterized by electron (UV-Vis) and vibrational spectroscopy in the Fourier Transform Infrared (FTIR) region, powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TGA/DTA). The in vivo toxicity and in vitro antimicrobial activity of the complex and the Ni-MOF were tested. The two compounds presented no toxicity at a concentration of 5000 μg mL-1, and showed inhibitory activity at 64 μg mL-1 in 24 h and at 128 μg mL-1 in 48 h against the yeast Candida albicans.

Metal-organic frameworks as thermocatalysts for hydrogen peroxide generation and environmental antibacterial applications

Reactive oxygen species (ROS) are highly reactive, making them useful for environmental and health applications. Traditionally, photocatalysts and piezocatalysts have been used to generate ROS, but their utilization is limited by various environmental and physical constraints. This study introduces metal-organic frameworks (MOFs) as modern thermocatalysts efficiently producing hydrogen peroxide (H2O2) from small temperature differences. Temperature fluctuations, abundant in daily life, offer tremendous potential for practical thermocatalytic applications. As proof of concept, MOF materials coated onto carbon fiber fabric (MOF@CFF) created a thermocatalytic antibacterial filter. The study compared three different MOFs (CuBDC, MOF-303, and ZIF-8) with bismuth telluride (Bi2Te3), a known thermocatalytic material. ZIF-8 demonstrated superior H2O2 generation under low-temperature differences, achieving 96% antibacterial activity through temperature variation cycles. This work advances potential in thermoelectric applications of MOFs, enabling real-time purification and disinfection through H2O2 generation. The findings open interdisciplinary avenues for leveraging thermoelectric effects in catalysis and various technologies.

Chitosan-ImH@γ-CD: a pH-sensitive smart bio-coating to enhance the corrosion resistance of magnesium alloys in bio-implants

Magnesium alloys hold promise as bio-implants but are hindered by poor corrosion resistance. To overcome this, a pH-sensitive smart anti-corrosion bio-coating was developed using a layer-by-layer technique. The first layer consists of Imidazol@waterproofed γ-Cyclodextrin metal organic framework (ImH@waterproofed γ-CD MOF), which encapsulates ImH, a green inhibitor, in waterproofed γ-CD MOF. The second layer is composed of 1% w/v chitosan. ImH@waterproofed γ-CD MOF was characterized by SEM, FTIR, and XRD. The corrosion parameters of the smart bio-coating were investigated through potentiodynamic polarization (Tafel) plots and electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). The results indicate that when the magnesium alloy coated with the chitosan-ImH@γ-CD composite is placed in the SBF solution, the pH near the corrosion site increases over time. This increase in pH leads to the release of imidazole as a corrosion inhibitor, effectively preventing surface corrosion by forming a protective layer on the alloy's surface. The chitosan-ImH@γ-CD composite exhibits an inhibition efficiency of 97.27% after 5 days of immersion in SBF. Additionally, the cell viability on the chitosan-ImH@γ-CD composite surface is significantly higher than on uncoated Mg alloy, promoting MC3T3-E1 cell proliferation. Alkaline phosphatase results also indicate improved differentiation of MC3T3-E1 cells with the chitosan-ImH@γ-CD composite.

BioMOF@cellulose Glycerogel Scaffold with Multifold Bioactivity: Perspective in Bone Tissue Repair

The development of new biomaterials for musculoskeletal tissue repair is currently an important branch in biomedicine research. The approach presented here is centered around the development of a prototypic synthetic glycerogel scaffold for bone regeneration, which simultaneously features therapeutic activity. The main novelty of this work lies in the combination of an open meso and macroporous nanocrystalline cellulose (NCC)-based glycerogel with a fully biocompatible microporous bioMOF system (CaSyr-1) composed of calcium ions and syringic acid. The bioMOF framework is further impregnated with a third bioactive component, i.e., ibuprofen (ibu), to generate a multifold bioactive system. The integrated CaSyr-1(ibu) serves as a reservoir for bioactive compounds delivery, while the NCC scaffold is the proposed matrix for cell ingrowth, proliferation and differentiation. The measured drug delivery profiles, studied in a phosphate-buffered saline solution at 310 K, indicate that the bioactive components are released concurrently with bioMOF dissolution after ca. 30 min following a pseudo-first-order kinetic model. Furthermore, according to the semi-empirical Korsmeyer-Peppas kinetic model, this release is governed by a case-II mechanism, suggesting that the molecular transport is influenced by the relaxation of the NCC matrix. Preliminary in vitro results denote that the initial high concentration of glycerol in the NCC scaffold can be toxic in direct contact with human osteoblasts (HObs). However, when the excess of glycerol is diluted in the system (after the second day of the experiment), the direct and indirect assays confirm full biocompatibility and suitability for HOb proliferation.

Understanding the Adsorption and Diffusion Behaviors of PBUT in Biocompatible MOFs

With the increasing incidence of chronic kidney disease, the effective control of protein-bound uremic toxins (PBUTs), which are difficult to remove through dialysis, has become a priority. In this study, the adsorption and diffusion behaviors of several metal-organic frameworks (MOFs) for PBUTs (indoxyl sulfate and p-cresyl sulfate) were studied by molecular dynamics (MD) simulations and umbrella sampling. For the NU series of MOFs, good correlations between the Gibbs free energy (ΔG) and the experimental clearance rates of PBUTs are found. For the adsorption behaviors, in terms of ΔG, DAJWET exhibits the best adsorption effect for indoxyl sulfate (IS), whereas NU-1000 shows the best effect for p-cresyl sulfate (pCS). Similar trends observed in the radial distribution function and mean square displacement results suggest that the π-π stacking interactions play a crucial role in the adsorption and diffusion of PBUTs by MOFs. Furthermore, it can be concluded that MOFs with highly conjugated groups (porphyrin rings and pyrene groups) tend to generate more PBUT attraction, and provide design principles for potential MOF candidates in the removal of PBUTs.

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

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

Recent advances and synergistic effect of bioactive zeolite imidazolate frameworks (ZIFs) for biosensing applications

The rapid developments in the field of zeolitic imidazolate frameworks (ZIFs) in recent years have created unparalleled opportunities for the development of unique bioactive ZIFs for a range of biosensor applications. Integrating bioactive molecules such as DNA, aptamers, and antibodies into ZIFs to create bioactive ZIF composites has attracted great interest. Bioactive ZIF composites have been developed that combine the multiple functions of bioactive molecules with the superior chemical and physical properties of ZIFs. This review thoroughly summarizes the ZIFs as well as the novel strategies for incorporating bioactive molecules into ZIFs. They are used in many different applications, especially in biosensors. Finally, biosensor applications of bioactive ZIFs were investigated in optical (fluorescence and colorimetric) and electrochemical (amperometric, conductometric, and impedance) fields. The surface of ZIFs makes it easier to immobilize bioactive molecules like DNA, enzymes, or antibodies, which in turn enables the construction of cutting-edge, futuristic biosensors.

MOF-Based Platform for Kidney Diseases: Advances, Challenges, and Prospects

Kidney diseases are important diseases that affect human health worldwide. According to the 2020 World Health Organization (WHO) report, kidney diseases have become the top 10 causes of death. Strengthening the prevention, primary diagnosis, and action of kidney-related diseases is of great significance in maintaining human health and improving the quality of life. It is increasingly challenging to address clinical needs with the present technologies for diagnosing and treating renal illness. Fortunately, metal-organic frameworks (MOFs) have shown great promise in the diagnosis and treatment of kidney diseases. This review summarizes the research progress of MOFs in the diagnosis and treatment of renal disease in recent years. Firstly, we introduce the basic structure and properties of MOFs. Secondly, we focus on the utilization of MOFs in the diagnosis and treatment of kidney diseases. In the diagnosis of kidney disease, MOFs are usually designed as biosensors to detect biomarkers related to kidney disease. In the treatment of kidney disease, MOFs can not only be used as an effective adsorbent for uremic toxins during hemodialysis but also as a precise treatment of intelligent drug delivery carriers. They can also be combined with nano-chelation technology to solve the problem of the imbalance of trace elements in kidney disease. Finally, we describe the current challenges and prospects of MOFs in the diagnosis and treatment of kidney diseases.

Green, mildly synthesized bismuth-based MOF for extraction of polar glucocorticoids in environmental water

The complex sample matrix and low environmental concentration make it challenging to effectively determine the polar glucocorticoids. In particular, a green, economical, and environmentally friendly method is urgently needed, since a large amount of extraction solvents, samples, and extraction materials have been commonly used to improve the sensitivity of the reported methods. In this study, a green and robust phenol and bismuth-based MOF of SU101 was mildly synthesized and fabricated as a brand new solid-phase microextraction (SPME) fiber. Only tiny amounts of SU101 and desorption solvents were employed to realize the high-efficiency enrichments of glucocorticoids from water samples. The detection performance of proposed SU101 fiber towards glucocorticoids was much superior to the single-component and multi-component commercial fibers. It indicated that SU101 fiber could be an excellent candidate for the enrichments of polar pharmaceuticals. After it was coupled with the instrument of high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), the linear range of 5-10000 ng L-1 with detection limits low to 0.070-1.5 ng L-1 and satisfactory recoveries were achieved by the developed method. Benefiting from the environmental friendliness of SU101 and the less-solvent consumption of SPME technique, this work presented a green and economical strategy for determinations of trace glucocorticoids.

CD-MOFs: From preparation to drug delivery and therapeutic application

Cyclodextrin metal-organic frameworks (CD-MOFs) show considerable advantages of edibility, degradability, low toxicity, and high drug loading, which have attracted enormous interest, especially in drug delivery. This review summarizes the typical synthesis approaches of CD-MOFs, the drug loading methods, and the mechanism of encapsulation and release. The influence of the structure of CD-MOFs on their drug encapsulation and release is highlighted. Finally, the challenges CD-MOFs face are discussed regarding biosafety assessment systems, stability in aqueous solution, and metal ion effect.

The green synthesis and applications of biological metal-organic frameworks for targeted drug delivery and tumor treatments

Biological metal-organic frameworks (bio-MOFs) constitute a growing subclass of MOFs composed of metals and bio-ligands derived from biology, such as nucleobases, peptides, saccharides, and amino acids. Bio-ligands are more abundant than other traditional organic ligands, providing multiple coordination sites for MOFs. However, bio-MOFs are typically prepared using hazardous or harmful solvents or reagents, as well as laborious processes that do not conform to environmentally friendly standards. To improve biocompatibility and biosafety, eco-friendly synthesis and functionalization techniques should be employed with mild conditions and safer materials, aiming to reduce or avoid the use of toxic and hazardous chemical agents. Recently, bio-MOF applications have gained importance in some research areas, including imaging, tumor therapy, and targeted drug delivery, owing to their flexibility, low steric hindrances, low toxicity, remarkable biocompatibility, surface property refining, and degradability. This has led to an exponential increase in research on these materials. This paper provides a comprehensive review of updated strategies for the synthesis of environmentally friendly bio-MOFs, as well as an examination of the current progress and accomplishments in green-synthesized bio-MOFs for drug delivery aims and tumor treatments. In conclusion, we consider the challenges of applying bio-MOFs for biomedical applications and clarify the possible research orientation that can lead to highly efficient therapeutic outcomes.

Aqueous chemistry of nalidixic acid and its complexes with biological relevant cations: A combination of potentiometric, UV spectrophotometric, MS and MS/MS study

Nalidixic acid (NAL) is a broad-spectrum antimicrobial widely used for urinary tract infections. As demonstrated, complexation of NAL with Zn2+, Mn2+ and Cu2+ was often used to get new formulations with an enhanced efficiency and potency. Therefore, the elucidation of behavior of NAL in solution and of its interaction with metal cations are crucial to better understand the influence of complexation on NAL efficiency and to find the optimal conditions to propose novel formulations. As a preliminary study, spectrophotometric titrations were carried out on NAL to determine the values of the protonation constants and to define its acid-base behavior. Then, the interaction with the three metal cations Zn2+, Mn2+ and Cu2+ was investigated by potentiometric and spectrophotometric titrations, varying the conditions of temperature, ionic strength and metal-ligand ratio, thus allowing to get the most robust speciation model and to determine the formation constants with Zn2+, Mn2+, and Cu2+ under different conditions, the sequestering ability of NAL towards metal cations, the formation enthalpic and entropic changes. A simulation under serum conditions was reported to show the relevance of the investigated species. Finally, LD-MS (laser desorption ionization mass spectrometry) and MS/MS analyses highlighted for all systems the formation of the complex species between Zn2+, Mn2+ and Cu2+ with NAL. MS/MS investigations assigned the sites of coordination of the ligand with the metal cation. More precisely, deprotonated NAL coordinates the metal cation via the oxygens of the carboxylate and the carbonyl groups.

Elucidating anticancer drugs release from UiO-66 as a carrier through the computational approaches

The computational analysis of drug release from metal-organic frameworks (MOFs), specifically UiO-66, is the primary focus of this research. MOFs are recognized as nanocarriers due to their crystalline structure, porosity, and potential for added functionalities. The research examines the release patterns of three drugs: temozolomide, alendronate, and 5-fluorouracil, assessing various factors such as the drugs' distance from the UiO-66 centers, the interaction of drug functional groups with Zr metal ions, and the drug density throughout the nanocarrier. Findings reveal that 5-fluorouracil is located furthest from the UiO-66 center and exhibits the highest positive energy compared to the other drugs. Alendronate's density is observed to shift to the carrier surface, while 5-fluorouracil's density significantly decreases within the system. The drug density diminishes as the distance from the UiO-66 center of mass increases, suggesting a stronger positive interaction between the drugs and the nanocarrier. Moreover, Monte Carlo calculations were employed to load drugs onto the UiO-66 surface, leading to a substantial release of 5-fluorouracil from UiO-66. Quantum and Monte Carlo adsorption localization calculations were also conducted to gather data on the compounds' energy and geometry. This research underscores the potential of MOFs as nanocarriers for drug delivery and highlights the crucial role of temperature in regulating drug release from UiO-66. It provides insights into the complex dynamics of drug release and the factors influencing it, thereby emphasizing the promise of UiO-66 as a viable candidate for drug delivery. This work contributes to our understanding of UiO-66's role and sets the stage for improved performance optimization in the cancer treatment.

Study on Gas Sorption and Iodine Uptake of a Metal-Organic Framework Based on Curcumin

Medi-MOF-1 is a highly porous Metal-Organic framework (MOF) constructed from Zn(II) and curcumin. The obtained crystal was characterized using powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). A micrometer-sized crystal with similar morphology was successfully obtained using the solvothermal method. Thanks to its high surface area, good stability, and abound pores, the as-synthesized medi-MOF-1 could be used as a functional porous material to adsorb different gases (H₂, CO₂, CH₄, and N₂) and iodine (I₂). The activated sample exhibited a high I₂ adsorption ability of 1.936 g g^-1 at room temperature via vapor diffusion. Meanwhile, the adsorbed I₂ could be released slowly in ethanol, confirming the potential application for I₂ adsorption.

Metal-organic coordination polymers for delivery of immunomodulatory agents, and infectious disease and cancer vaccines

Metal-organic coordination polymers (CPs) are a broad class of materials that include metal-organic frameworks (MOFs). CPs are highly ordered crystalline materials that are composed of metal ions (or metal ion clusters) and multidentate organic ligands that serve as linkers. One-, two-, and three-dimensional CPs can be formed, with 2D and 3D structures referred to as MOFs. CPs have gained a lot of attention due to attractive structural features like structure versatility and tunability, and well-defined pores that enable the encapsulation of cargo. Further, CPs show a lot of promise for drug delivery applications, but only a very limited number of CPs are currently being evaluated in clinical trials. In this review, we outlined features that are desired for CP-based drug delivery platform, and briefly described most relevant characterization techniques. We highlighted some of the recent efforts directed toward developing CP-based drug delivery platforms with the emphasis on vaccines against cancer, infectious diseases, and viruses. We hope this review will be a helpful guide for those interested in the design and evaluation of CP-based immunological drug delivery platforms. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Short-Peptide Supramolecular Hydrogels for In Situ Growth of Metal-Organic Framework-Peptide Biocomposites

The development of bio-MOFs or MOF biocomposites through the combination of MOFs with biopolymers offers the possibility of expanding the potential applications of MOFs, making use of more environmentally benign processes and reagents and giving rise to a new generation of greener and more bio-oriented composite materials. Now, with the increasing use of MOFs for biotechnological applications, the development of new protocols and materials to obtain novel bio-MOFs compatible with biomedical or biotechnological uses is needed. Herein, and as a proof of concept, we have explored the possibility of using short-peptide supramolecular hydrogels as media to promote the growth of MOF particles, giving rise to a new family of bio-MOFs. Short-peptide supramolecular hydrogels are very versatile materials that have shown excellent in vitro and in vivo biomedical applications such as tissue engineering and drug delivery vehicles, among others. These peptides self-assemble by noncovalent interactions, and, as such, these hydrogels are easily reversible, being more biocompatible and biodegradable. These peptides can self-assemble by a multitude of stimuli, such as changes in pH, temperature, solvent, adding salts, enzymatic activity, and so forth. In this work, we have taken advantage of this ability to promote peptide self-assembly with some of the components required to form MOF particles, giving rise to more homogeneous and well-integrated composite materials. Hydrogel formation has been triggered using Zn²⁺ salts, required to form ZIF-8, and formic acid, required to form MOF-808. Two different protocols for the in situ MOF growth have been developed. Finally, the MOF-808 composite hydrogel has been tested for the decontamination of water polluted with phosphate ions as well as for the catalytic degradation of toxic organophosphate methyl paraoxon in an unbuffered solution.

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.

Peptide-derived coordination frameworks for biomimetic and selective separation

Peptide-derived metal-organic frameworks (PMOFs) have emerged as a class of biomimetic materials with attractive performances in analytical and bioanalytical chemistry. The incorporation of biomolecule peptides gives the frameworks conformational flexibility, guest adaptability, built-in chirality, and molecular recognition ability, which greatly accelerate the applications of PMOFs in enantiomeric separation, affinity separation, and the enrichment of bioactive species from complicated samples. This review focuses on the recent advances in the engineering and applications of PMOFs in selective separation. The unique biomimetic size-, enantio-, and affinity-selective performances for separation are discussed along with the chemical structures and functions of MOFs and peptides. Updates of the applications of PMOFs in adaptive separation of small molecules, chiral separation of drug molecules, and affinity isolation of bioactive species are summarized. Finally, the promising future and remaining challenges of PMOFs for selective separation of complex biosamples are discussed.

MIL-100(Fe)-Based Composite Films for Food Packaging

A biocompatible metal-organic framework MIL-100(Fe) loaded with the active compounds of tea tree essential oil was used to produce composite films based on κ-carrageenan and hydroxypropyl methylcellulose with the uniform distribution of the particles of this filler. The composite films featured great UV-blocking properties, good water vapor permeability, and modest antibacterial activity against both Gram-negative and Gram-positive bacteria. The use of metal-organic frameworks as containers of hydrophobic molecules of natural active compounds makes the composites made from naturally occurring hydrocolloids attractive materials for active packaging of food products.

BioMOF-Based Anti-Cancer Drug Delivery Systems

A variety of nanomaterials have been developed specifically for biomedical applications, such as drug delivery in cancer treatment. These materials involve both synthetic and natural nanoparticles and nanofibers of varying dimensions. The efficacy of a drug delivery system (DDS) depends on its biocompatibility, intrinsic high surface area, high interconnected porosity, and chemical functionality. Recent advances in metal-organic framework (MOF) nanostructures have led to the achievement of these desirable features. MOFs consist of metal ions and organic linkers that are assembled in different geometries and can be produced in 0, 1, 2, or 3 dimensions. The defining features of MOFs are their outstanding surface area, interconnected porosity, and variable chemical functionality, which enable an endless range of modalities for loading drugs into their hierarchical structures. MOFs, coupled with biocompatibility requisites, are now regarded as highly successful DDSs for the treatment of diverse diseases. This review aims to present the development and applications of DDSs based on chemically-functionalized MOF nanostructures in the context of cancer treatment. A concise overview of the structure, synthesis, and mode of action of MOF-DDS is provided.

Exploring Helical Peptides and Foldamers for the Design of Metal Helix Frameworks: Current Trends and Future Perspectives

Flexible and biocompatible metal peptide frameworks (MPFs) derived from short and ultra-short peptides have been explored for the storage of greenhouse gases, molecular recognition, and chiral transformations. In addition to short flexible peptides, peptides with specifically folded conformations have recently been utilized to fabricate a variety of metal helix frameworks (MHFs). The secondary structures of the peptides govern the structure-assembly relationship and thereby control the formation of three-dimensional (3D)-MHFs. Particularly, the hierarchical structural organization of peptide-based MHFs has not yet been discussed in detail. Here, we describe the recent progress of metal-driven folded peptide assembly to construct 3D porous structures for use in future energy storage, chiral recognition, and biomedical applications, which could be envisioned as an alternative to the conventional metal-organic frameworks (MOFs).

Coordination Polymers Constructed from an Adaptable Pyridine-Dicarboxylic Acid Linker: Assembly, Diversity of Structures, and Catalysis

4,4'-(Pyridine-3,5-diyl)dibenzoic acid (H2pdba) was explored as an adaptable linker for assembling a diversity of new manganese(II), cobalt(II/III), nickel(II), and copper(II) coordination polymers (CPs): [Mn(μ4-pdba)(H2O)]n (1), {[M(μ3-pdba)(phen)]·2H2O}n (M = Co (2), Ni (3)), {[Cu2(μ3-pdba)2(bipy)]·2H2O}n (4), {[Co(μ3-pdba)(bipy)]·2H2O}n (5), [Co2(μ3-pdba)(μ-Hbiim)2(Hbiim)]n (6), and [M(μ4-pdba)(py)]n (M = Co (7), Ni (8)). The CPs were hydrothermally synthesized using metal(II) chloride precursors, H2pdba, and different coligands functioning as crystallization mediators (phen: 1,10-phenanthroline; bipy: 2,2'-bipyridine, H2biim: 2,2'-biimidazole; py: pyridine). Structural networks of 1-8 range from two-dimensional (2D) metal-organic layers (1-3, 5-8) to three-dimensional (3D) metal-organic framework (MOF) (4) and disclose several types of topologies: sql (in 1), hcb (in 2, 3, 5), tfk (in 4), 3,5L66 (in 6), and SP 2-periodic net (6,3)Ia (in 7, 8). Apart from the characterization by standard methods, catalytic potential of the obtained CPs was also screened in the Knoevenagel condensation of benzaldehyde with propanedinitrile to give 2-benzylidenemalononitrile (model reaction). Several reaction parameters were optimized, and the substrate scope was explored, revealing the best catalytic performance for a 3D MOF 4. This catalyst is recyclable and can lead to substituted dinitrile products in up to 99% product yields. The present study widens the use of H2pdba as a still poorly studied linker toward designing novel functional coordination polymers.

Nanoscale MOFs: From synthesis to drug delivery and theranostics applications

Since the first report in 1989, Metal-Organic Frameworks (MOFs) self-assembled from metal ions or clusters, as well as organic linkers, have attracted extensive attention. Due to their flexible composition, large surface areas, modifiable surface properties, and their degradability, there has been an exponential increase in the study of MOFs materials, specifically in drug delivery system areas such as infection, diabetes, pulmonary disease, ocular disease, imaging, tumor therapy, and especially cancer theranostics. In this review, we discuss the trends in MOFs biosafety, from "green" synthesis to applications in drug delivery systems. Firstly, we present the different "green" synthesis approaches used to prepare MOFs materials. Secondly, we detail the methods for the functional coating, either through grafting targeting units, poly(ethylene glycol) (PEG) chains or by using cell membranes. Then, we discuss drug encapsulation strategies, host-guest interactions, as well as drug release mechanisms. Lastly, we report on the drug delivery applications of nanoscale MOFs. In particular, we discuss MOFs-based imaging techniques, including magnetic resonance imaging (MRI), photoacoustic imaging (PAI), positron emission tomography (PET), and fluorescence imaging. MOFs-based cancer therapy methods are also presented, such as photothermal therapy (PTT), photodynamic therapy (PDT), radiotherapy (RT), chemotherapy, and immunotherapy.

A review of synthesis, fabrication, and emerging biomedical applications of metal-organic frameworks

The overwhelming potential of porous coordination polymers (PCP), also known as Metal-Organic Frameworks (MOFs), especially their nanostructures for various biomedical applications, have made these materials worth investigating for more applications and uses. MOFs unique structure has enabled them for most applications, particularly in biomedical and healthcare. A number of very informative review papers are available on the biomedical applications of MOFs for the reader's convenience. However, many of those reviews focus mainly on drug delivery applications, and no significant work has been reported on other MOFs for biomedical applications. This review aims to present a compact and highly informative global assessment of the recent developments in biomedical applications (excluding drug-delivery) of MOFs along with critical analysis. Researchers have recently adopted both synthetic and post-synthetic routes for the fabrication and modification of MOFs that have been discussed and analyzed. A critical review of the latest reports on the significant and exotic area of bio-sensing capabilities and applications of MOFs has been given in this study. In addition, other essential applications of MOFs, including photothermal therapy, photodynamic therapy, and antimicrobial activities, are also included. These recently grown emergent techniques and cancer treatment options have gained attention and require further investigations to achieve fruitful outcomes. MOF's role in these applications has been thoroughly discussed, along with future challenges and valuable suggestions for the research community that will help meet future demands.

Therapeutic Potential of a Water-Soluble Silver-Diclofenac Coordination Polymer on 3D Pancreatic Cancer Spheroids

This work describes the traditional wet and green synthetic approaches, structural features, and extensive bioactivity study for a new coordination polymer [Ag(μ-PTA)(Df)(H₂O)]_n·3nH₂O (1) that bears a silver(I) center, a 1,3,5-triaza-phosphaadamantane (PTA) linker, and a nonsteroidal anti-inflammatory drug, diclofenac (Df^-). Compared to cisplatin, compound 1 exhibits both anti-inflammatory properties and very remarkable cytotoxicity toward various cancer cell lines with a high value of selectivity index. Additionally, the 3D model representing human pancreas/duct carcinoma (PANC-1) and human lung adenocarcinoma (A549) was designed and applied as a clear proof of the remarkable therapeutic potential of 1. The obtained experimental data indicate that 1 induces an apoptotic pathway via reactive oxygen species generation, targeting mitochondria due to their membrane depolarization. This study broadens a group of bioactive metal-organic networks and highlights the significant potential of such compounds in developing advanced therapeutic solutions.

Cyclodextrin metal-organic frameworks and derivatives: recent developments and applications

While there is a tremendous amount of scientific research on metal organic frameworks (MOFs) for gas storage/separation, catalysis and energy storage, the development and application of biocompatible MOFs still poses major challenges. In general, they can be synthesised from various biocompatible linkers and metal ions but particularly cyclodextrins (CDs) as cyclic oligosaccharides are an astute choice for the former. Although the field of CD-MOF materials is still in the early stages and their design and fabrication comes with many hurdles, the benefits coming from CDs built in a porous framework are exciting. Versatile host-guest complexation abilities, high encapsulation capacity and hydrophilicity are among the valuable properties inherent to CDs and offer extended and novel applications to MOFs. In this review, we provide an overview of the state-of-the-art synthesis, design, properties and applications of these materials. Initially, a rationale for the preparation of CD-based MOFs is provided, based on the chemical and structural properties of CDs and including their advantages and disadvantages. Further on, the review exhaustively surveys CD-MOF based materials by categorising them into three sub-classes, namely (i) CD-MOFs, (ii) CD-MOF hybrids, obtained via combination with external materials, and (iii) CD-MOF-derived materials prepared under pyrolytic conditions. Subsequently, CD-based MOFs in practical applications, such as drug delivery and cancer therapy, sensors, gas storage, (enantiomer) separations, electrical devices, food industry, and agriculture, are discussed. We conclude by summarizing the state of the art in the field and highlighting some promising future developments of CD-MOFs.

Engineering Bio-MOF/polydopamine as a biocompatible targeted theranostic system for synergistic multi-drug chemo-photothermal therapy

In this study, a biodegradable multifunctional photothermal drug delivery nanoparticles (MPH NPs) using curcumin (Cur) as the ligand coated with hyaluronic acid (HA) was successfully prepared, which could simultaneously deliver Cur and doxorubicin hydrochloride (DOX·HCl) to overcome the common drug resistance in cancer cells. Polydopamine (PDA) as a protective shell prevents premature degradation of Cur in physiological environment and enables it to play effective medicinal value. MPH NPs can specifically recognize CD44 receptors on the surface of cancer cells for tumor targeting, with the damage of the partially released DOX to the superficial tumor cells, and then the positively charged Cur released may gradually penetrate into the cells through electron interaction to improve the problem of low permeability. In vitro cell experiments showed that hydrophobic/hydrophilic drugs co-loaded MPDH (MPH loaded with DOX·HCl) could enter the cancer cells through the endocytosis mediated by clathrin / caveolin, and the inhibition rate of MPDH on HeLa cells reached 79.28 % irradiation under 808 nm laser. MPH were composed of safe materials that have been proven to be biodegradable in human body, which avoided the disadvantages that NPs were difficult to discharge and caused damage to normal organs during long-term use.

Bioactive 2D nanomaterials for neural repair and regeneration

Biomaterials have provided promising strategies towards improving the functions of injured tissues of the nervous system. Recently, 2D nanomaterials, such as graphene, layered double hydroxides (LDHs), and black phosphorous, which are characterized by ultrathin film structures, have attracted much attention in the fields of neural repair and regeneration. 2D nanomaterials have extraordinary physicochemical properties and excellent biological activities, such as a large surface-area-to-thickness ratio, high levels of adhesion, and adjustable flexibility. In addition, they can be designed to have superior biocompatibility and electrical or nano-carrier properties. To date, many 2D nanomaterials have been used for synaptic modulation, neuroinflammatory reduction, stem cell fate regulation, and injured neural cell/tissue repair. In this review, we discuss the advances in 2D nanomaterial technology towards novel neurological applications and the mechanisms underlying their unique features. In addition, the future outlook of functional 2D nanomaterials towards addressing the difficult issues of neuropathy has been explored to introduce a promising strategy towards repairing and regenerating the injured nervous system.

Immunogenicity-boosted cancer immunotherapy based on nanoscale metal-organic frameworks

Immunotherapy, including checkpoint blockade immunotherapy (CBI), has witnessed remarkable progress in cancer therapy. Nonetheless, significant obstacles to successful immunotherapy remain. Notably, tumour non-responsiveness to immunotherapy due to immunosuppressive tumour microenvironments (TMEs). To revitalize immunosuppressive TMEs various therapeutic strategies have been reported by researchers. Immunostimulatory adjuvant treatments (IAT) are the most widely investigated ones. Due to their biodegradability, compositional tenability, and inherent immune effectiveness, nanoscale metal-organic frameworks (nMOFs) with metal nodes and organic linkers can be used as versatile nanomaterials for IAT. This review summarizes the progress in nMOF-based tumour immunotherapy in promoting immunostimulatory TMEs. And in combination with other cancer immunotherapies to increase tumour immunogenicity and antitumor efficacy. Finally, the challenges of nMOFs in tumour immunotherapy are also discussed.

Investigation of the Flotation Separation of Scheelite from Fluorite with a Novel Chelating Agent: Pentasodium Diethylenetriaminepentaacetate

The recovery of scheelite from calcium-bearing carbonate ores by foam flotation is challenging due to its low separation efficiency. This study investigated the effect of pentasodium diethylenetriaminepentaacetate (PD) on the surface properties of scheelite and fluorite. For this purpose, we performed micro-flotation tests and carried out zeta potential measurements, as well as Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopic measurements, in order to analyze the surface properties of these minerals. The addition of PD as a novel depressor significantly improved the effect of fluorite and sodium oleate (NaOl) on the flotation-based scheelite recovery and separation from fluorite. PD was spontaneously adsorbed onto fluorite through electrostatic and chemical adsorption. By contrast, PD did not appear on the scheelite because of the reaction conditions, surface site, and steric hindrance. X-ray photoelectron spectroscopy measurements and a solution chemistry analysis were used for the determination of the PD-selective adsorption mechanism and key factors derived from multi-layer adsorption onto fluorite, which completely hindered that of NaOl.

Ratiometric Thermometers Based on Rhodamine B and Fluorescein Dye-Incorporated (Nano) Cyclodextrin Metal-Organic Frameworks

Macro- and nanosized core, as well as core-shell, γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) have been designed and used as platforms for the encapsulation of dye molecules to develop the first CD-MOF-based ratiometric optical thermometer materials. A novel dye combination was employed for this purpose, i.e., the duo rhodamine B (RhB) and fluorescein (FL). RhB is highly temperature-sensitive, whereas FL is less temperature-sensitive, and its luminescence emission peak is used as a reference. Promising results in terms of thermometric properties were obtained for a series of dye-encapsulated γ-CD-MOF materials based on this dye combination, with high relative sensitivities, even up to 5%K^-1, for the dye-encapsulated 75%RhB-25%FL nanosized γ-CD-MOF, among the highest performance values reported so far for luminescent dual thermometers. In our study, we have additionally developed a simple yet effective preparation method for core-shell γ-CD-MOFs, allowing effective manipulation of the γ-CD-MOF shell growth. The proposed method allows incorporation of the FL and RhB dyes in the γ-CD-MOFs in a more controlled manner, enhancing the efficiency of the developed ratiometric (macro) γ-CD-MOF thermometers.

Manganese complexes and manganese-based metal-organic frameworks as contrast agents in MRI and chemotherapeutics agents: Applications and prospects

Manganese-based Metal-organic Frameworks (Mn-MOFs) represents a unique sub-class of MOFs with low toxicity, oxidative ability, and biocompatibility, which plays vital role in the application of this class of MOFs in medical field. Mn-MOFs show great potential in biomedical applications, and has been extensively studied as compared to other MOFs in transition metal series. They are important in medical applications because Mn(II) possess large electron spin number and longer electron relaxation time. They display fast water exchange rate and could be employed as a potential MRI contrast agent because of their strong targeting ability. Manganese complexes with different ligands also display prospective applications in area such as carrier for drug targeting in anti-tumor and antimicrobial therapy. In the review presented herewith, the application of Mn-based complexes and Mn-MOFs have been emphasized in the area such as imaging viz. MRI, multimodal imaging, antitumor activities such as chemodynamic therapy, photodynamic therapy, sonodynamic therapy and antimicrobial applications. Also, how rational designing and syntheses of targeted Mn-based complexes and Mn-MOFs can engender desired applications.

A biocompatible bismuth based metal-organic framework as efficient light-sensitive drug carrier

The low toxicity and good photo active property endow bismuth based metal-organic frameworks (MOFs) potential candidates for efficient light-sensitive drug carrier. In this work, SU-101, composed of Bi and ellagic acid (EA), is found to display high ciprofloxacin (CIP) loading ratio (85.8%) and controlled CIP release under light illumination (the maximum CIP release ratio is 95.56%). Further investigations suggest that hydrogen bond between the CO group in EA and the -OH group in CIP is responsible for above behavior. Light irradiation decreases the electron density around the CO group in EA, which consequently leads to the broken of the hydrogen bond and therefore the release of CIP. Further investigations suggest that SU-101 is universal for other drugs, such as norfloxacin (NOR), amoxicillin (AMO), tetracycline (TET) and doxorubicinhydrochloride (DOX), since all of them can form hydrogen bond with SU-101. This work suggests that SU-101 holds great potential as efficient light-sensitive drug carrier, and the investigation of other Bi based MOFs as drug carrier is under investigation.

Design and degradation of permanently porous vitamin C and zinc-based metal-organic framework

Bioapplication is an emerging field of metal-organic frameworks (MOF) utilization, but biocompatible MOFs with permanent porosity are still a rarity in the field. In addition, biocompatibility of MOF constituents is often overlooked when designing bioMOF systems, intended for drug delivery. Herein, we present the a Zn(II) bioMOF based on vitamin C as an independent ligand (bioNICS-1) forming a three-dimensional chiral framework with permanent microporosity. Comprehensive study of structure stability in biorelavant media in static and dynamic conditions demonstrates relatively high structure resistivity, retaining a high degree of its parent specific surface area. Robustness of the 3D framework enables a slow degradation process, resulting in controllable release of bioactive components, as confirmed by kinetic studies. BioNICS-1 can thus be considered as a suitable candidate for the design of a small drug molecule delivery system, which was demonstrated by successful loading and release of urea-a model drug for topical application-within and from the MOF pores.

What are the prospects for using complexes of copper(ii) and zinc(ii) to suppress the vital activity of Mycolicibacterium smegmatis?

New complexes of zinc(ii) and copper(ii) with 2-furoic acid (Hfur), acetic acids and N-donor ligands with the compositions [Zn2(fur)4] n (1), [Zn2(fur)4(NH2py)2] (2, NH2py = 3-aminopyridine), [Zn(fur)2(neoc)] (3, neoc = 2,9-dimethyl-1,10-phenantroline), [Zn(OAc)2(neoc)] (4, OAc = acetat-anion), and [Cu(fur)2(neoc)(H2O)] (5) were synthesized. The structures of the compounds were established by single crystal X-ray diffraction analysis. Complexes 1 and 2 are binuclear; whereas 3-5 are mononuclear. The stabilization of supramolecular architectures in crystals for compounds 1-5 occurs due to π-π-bonding between heterocycles and hydrogen interactions that provide good solubility in aqueous solutions. The stability of the complexes upon dissolution in 5% dextrose and 0.9% NaCl was confirmed by UV-vis spectroscopic and NMR (1H) data. The study of in vitro biological activity was carried out against the non-pathogenic strain of Mycolicibacterium smegmatis that is a model for M. tuberculosis. The synergistic effect of ligands is observed for complexes 3-5 and is characterized by an increase in the biological activity values. On passage from Zn2+ to Cu2+ complexes, the biological activity increases and the maximum effect is observed for compound [Cu(fur)2(phen)]. Analysis of the transcriptomic profiles of the M. smegmatis mc 2 155 strain under the pressure of the copper complex [Cu(fur)2(phen)] made it possible to isolate 185 genes, one quarter of which are associated with the compensation of iron deficiency in the bacterial strain. Genes associated with the transport and metabolism of heavy metals, biosynthesis of fatty and amino acids, biodegradation and transport of urea were also isolated.

Biocompatible 2D Cu-TCPP Nanosheets Derived from Cu2O Nanocubes as Multifunctional Nanoplatforms for Combined Anticancer Therapy

Two-dimensional (2D) metal-organic frameworks (MOFs) could serve as multifunctional nanoplatforms to load small-molecule drugs and enzyme-mimicking nanoparticles (NPs) with a high efficiency for combined cancer therapy. Herein, we have prepared novel 2D Cu-tetrakis (4-carboxyphenyl) porphyrin (TCPP) nanosheets with an average thickness of 1.2 ± 0.1 nm using Cu₂O nanocubes (50 nm) as a template and solid copper ion supplier. Cu₂O nanocubes can be consumed and hybridized with the obtained Cu-TCPP, depending on the molar ratio of Cu₂O and TCPP linker. The resultant Cu₂O/Cu-TCPP could serve as nanoplatforms for co-loading of Pt and Au NPs to construct multifunctional Cu₂O/Cu-TCPP/(Pt-Au) nanomedicines, which showed a superior anticancer effect via multiple therapeutic modes. For instance, Cu(II)-TCPP can produce ¹O₂ in the presence of acidic H₂O₂ by the Russell mechanism and the intrinsic Cu(I) ions (derived from the residual Cu₂O) could mediate a Fenton-like reaction in tumorous tissues to generate toxic hydroxyl radicals (•OH). Moreover, the loaded Pt NPs with catalase (CAT)-mimic activity could decompose hydrogen peroxide (H₂O₂) into O₂ within the tumor cells, increasing the local O₂ concentration, modulating the tumorous hypoxia atmosphere, and promoting the O₂-dependent glucose oxidation reaction. Furthermore, Au NPs with glucose oxidase (GOx)-mimic activity could accelerate the consumption of glucose and cut nutrient supply to induce starvation therapy. Consequently, our designed 2D MOF-based therapeutic nanomedicines would be a promising candidate for future smart and combined cancer therapy.

Silver(I)-Tazobactam Frameworks with Improved Antimicrobial Activity

Tazobactam (TazoH) is a penicillinate sulfone β-lactamase inhibitor with negligible antimicrobial activity, commonly used with other antibiotics to provide an effective combination against many susceptible organisms expressing β-lactamases. Two novel Ag(I)-tazobactam frameworks ([Ag(I)-Tazo] and [Ag(I)-Tazo2]) prepared by mechanochemistry are presented herein as alternative forms to improve the antimicrobial activity of tazobactam by exploring synergistic effects with silver, being the first crystal structures reported of tazobactam coordinating to a metal site. The topological analysis of the 3D ([Ag(I)-Tazo]) and 2D+1D ([Ag(I)-Tazo2]) frameworks revealed underlying nets with the cbs (CrB self-dual) and decorated sql topologies, respectively. These novel frameworks are stable and show an enhanced antimicrobial activity when compared to tazobactam alone. Amongst the tested microorganisms, Pseudomonas aeruginosa is the most sensitive to tazobactam and the new compounds. This study thus unveils novel facets of tazobactam chemistry and opens up its application as a multifunctional linker for the design of antibiotic coordination frameworks and related materials.

Metal-biomolecule frameworks (BioMOFs): a novel approach for "green" optoelectronic applications

In this study, a water-stable microcrystalline bioMOF was synthesized, characterized, and loaded with silver ions or highly emissive rare earth (RE) metals such as Eu3+/Tb3+. The obtained materials were used as active layers in a proof-of-concept sustainable light-emitting device, highlighting the potential of bioMOFs in optoelectronic applications.

PDMS-coated γCD-MOF solid-phase microextraction fiber for BTEX analysis with boosted performances

Owing to the ubiquitous occurrence and chemotoxicity of BTEX (benzene, toluene, ethylbenzene and xylene), the development of stable and accurate analysis methods that can assess environment risks and can generate monitoring data rapidly is urgent. In this work, a new strategy was proposed for efficient detection of BTEX. By creatively utilizing thermal deposition method, a robust SPME fiber was fabricated, where the γCD-MOF acted as the adsorbent, while PDMS functionalized as the adhesive and protective coating. Benefiting from the protection of PDMS, the γCD-MOF fiber presented significantly better extraction performance and exhibited long-term structural stabilities in aqueous or methanol samples up to a week. The stable and improved properties of γCD-MOF demonstrated that the PDMS protected the MOF components from the adverse effects of solvent. The detection limits of PDMS modified γCD-MOF fiber for BTEX was as low as 0.13-0.29 ng L^-1 that accompanied with wide linear range of 1-1000 ng L^-1, which was significantly superior to commercial PDMS fiber and other MOF-based fibers. Besides, the feasibility of the proposed method was verified by the quantitative determination of BTEX in real water samples. This work presents an effective strategy for creating ultrasensitive and stable SPME fibers based on γCD-MOF for applications in aqueous samples or other poor solvent.

Post-synthetic modification of Prussian blue type nanoparticles: tailoring the chemical and physical properties

This review focuses on recent advances in the post-synthetic modification of nano-sized Prussian blue and its analogues and compares them with the current strategies used in metal–organic frameworks to give future outlooks in this field.