Synthesis of hollow nanocages MOF-5 as drug delivery vehicle to solve the load-bearing problem of insoluble antitumor drug oleanolic acid (OA)

Recent advances in the chemistry and biology of oleanolic acid and its derivatives

The pentacyclic triterpenes represent a significant class of plant bioactives with a variety of structures and a wide array of biological activities. These are biosynthetically produced via the mevalonate pathway although occasionally mixed pathways may also occur to introduce structural divergence. Oleanolic acid is one of the most explored bioactive from this class of compounds and possesses a broad spectrum of pharmacological and biological activities including liver protection, anti-cancer, atherosclerosis, anti-inflammation, antibacterial, anti-HIV, anti-oxidative, anti-diabetic etc. This review provides an overview of the latest research findings, highlighting the versatile medicinal and biological potential of oleanolic and its future prospects.

A novel strategy for the synthesis of samarium/europium-metal organic frameworks, and their utilization for detection of Cr3+, Pb2+, and acetone as a luminescent sensor with superior selectivity and sensitivity properties

With outstanding detection selectivity and sensitivity characteristics, samarium/europium-metal organic frameworks (Sm/Eu-MOF) is capable of functioning as a versatile light-emitting sensor particularly for detecting acetone, Cr3+, and Pb2+ in aqueous environment. While considering maximum detectable concentrations of 0.85 μM, 0.46 μM, and 1.04 μM, respectively, competitive energy interactions for acetone, absorption of energy for Cr3+, and substitution of ions for Pb2+ are the elucidated mechanisms of detecting these substances by Sm/Eu-MOF. Successful formulation and synthesis of a core-shell structured Sm/Eu-MOF, which has endurance to acid/alkali conditions and hydration/heat-stability, can be accomplished by utilizing Samarium and Europium nitrate ions, terephthalic acid, and 2, 5-furandicarboxylic acid. The recovery rate of acetone, Cr3+, and Pb2+ detection from real samples were 95.0-101.0 %, 99.8-101.0 %, and 99.9-104.0 %, respectively.

Exploring Synthesis Strategies and Interactions between MOFs and Drugs for Controlled Drug Loading and Release, Characterizing Interactions Through Advanced Techniques

This study explores various aspects of Metal-Organic Frameworks (MOFs), focusing on synthesis techniques to adjust pore size and key ligands and metals for crafting carrier MOFs. It investigates MOF-drug interactions, including hydrogen bonding, van der Waals, and electrostatic interactions, along with kinetic studies. The multifaceted applications of MOFs in drug delivery systems are elucidated. The morphology and structure of MOFs are intricately linked to synthesis methodology, impacting attributes like crystallinity, porosity, and surface area. Hydrothermal synthesis yields MOFs with high crystallinity, suitable for catalytic applications, while solvothermal synthesis generates MOFs with increased porosity, ideal for gas and liquid adsorption. Understanding MOF-drug interactions is crucial for optimizing drug delivery, affecting charge capacity, stability, and therapeutic efficacy. Kinetic studies determine drug release rates and uniformity, vital for controlled drug delivery. Overall, comprehending drug-MOF interactions and kinetics is essential for developing effective and controllable drug delivery systems.

Unlocking the Potential of Oleanolic Acid: Integrating Pharmacological Insights and Advancements in Delivery Systems

The growing interest in oleanolic acid (OA) as a triterpenoid with remarkable health benefits prompts an emphasis on its efficient use in pharmaceutical research. OA exhibits a range of pharmacological effects, including antidiabetic, anti-inflammatory, immune-enhancing, gastroprotective, hepatoprotective, antitumor, and antiviral properties. While OA demonstrates diverse pharmacological effects, optimizing its therapeutic potential requires overcoming significant challenges. In the field of pharmaceutical research, the exploration of efficient drug delivery systems is essential to maximizing the therapeutic potential of bioactive compounds. Efficiently delivering OA faces challenges, such as poor aqueous solubility and restricted bioavailability, and to unlock its full therapeutic efficacy, novel formulation strategies are imperative. This discussion thoroughly investigates different approaches and advancements in OA drug delivery systems with the aim of enhancing the biopharmaceutical features and overall efficacy in diverse therapeutic contexts.

Sub-acute administration of metal-organic Framework-5 induces behavioral impairments and augments the levels of oxidative stress and inflammation in the brain of rats

Metal-organic frameworks (MOFs) are known as potential pharmaceutical carriers because of their structure. Here, we evaluated the sub-acute administrations of MOF-5 on behavioral parameters, oxidative stress, and inflammation levels in rats. Thirty-two male Wistar rats received four injections of saline or MOF-5 at different doses which were 1, 10, and 50 mg/kg via caudal vein. Y-Maze and Morris-Water Maze (MWM) tests were used to explore working memory and spatial learning and memory, respectively. The antioxidant capacity and oxidative stress level of brain samples were assessed by ferric reducing antioxidant power (FRAP) and thiobarbituric acid-reacting substance (TBARS) assay, respectively. The expression levels of GFAP, IL-1β, and TNF-α were also measured by quantitative real-time reverse-transcription PCR (qRT-PCR). Sub-acute administration of MOF-5 reduced the spatial learning and memory as well as working memory, dose-dependently. The levels of FRAP were significantly reduced in rats treated with MOF-5 at higher doses. The Malondialdehyde (MDA) levels increased at the dose of 50 mg/kg. Additionally, the expression levels of IL-1β and TNF-α were significantly elevated in the rats' brains that were treated with MOF-5. Our findings indicate that sub-acute administration of MOF-5 induces cognitive impairment dose-dependently which might be partly mediated by increasing oxidative stress and inflammation.

Biomedical application of metal-organic frameworks (MOFs) in cancer therapy: Stimuli-responsive and biomimetic nanocomposites in targeted delivery, phototherapy and diagnosis

The nanotechnology is an interdisciplinary field that has become a hot topic in cancer therapy. Metal-organic frameworks (MOFs) are porous materials and hybrid composites consisted of organic linkers and metal cations. Despite the wide application of MOFs in other fields, the potential of MOFs for purpose of cancer therapy has been revealed by the recent studies. High surface area and porosity, significant drug loading and encapsulation efficiency are among the benefits of using MOFs in drug delivery. MOFs can deliver genes/drugs with selective targeting of tumor cells that can be achieved through functionalization with ligands. The photosensitizers and photo-responsive nanostructures including carbon dots and gold nanoparticles can be loaded in/on MOFs to cause phototherapy-mediated tumor ablation. The immunogenic cell death induction and increased infiltration of cytotoxic CD8+ and CD4+ T cells can be accelerated by MOF platforms in providing immunotherapy of tumor cells. The stimuli-responsive MOF platforms responsive to pH, redox, enzyme and ion can accelerate release of therapeutics in tumor site. Moreover, MOF nanocomposites can be modified ligands and green polymers to improve their selectivity and biocompatibility for cancer therapy. The application of MOFs for the detection of cancer-related biomarkers can participate in the early diagnosis of patients.

Formulation of lactoferrin decorated dextran based chitosan-coated europium metal-organic framework for targeted delivery of curcumin

Hepatocellular carcinoma (HPTC) currently ranks as the third leading cause of cancer-related mortality, necessitating an advanced formulation strategy. Recently, lactoferrin (Lf) has been utilized as a specific targeting ligand in HPTC due to its high specificity towards the asialoglycoprotein receptor expressed in cancer cells. Therefore, we present the fabrication of an Lf-decorated carboxymethyl dextran-encased chitosan-coated europium metal-organic framework-based nanobioconjugate (Lf-CMD-CS-CUR@Eu-MOF) for targeted curcumin (CUR) delivery. Briefly, CUR was loaded into Eu-MOF, followed by coating cationic 'CS' on the CUR@Eu-MOF surface. Simultaneously, Lf-decorated CMD was prepared via an esterification reaction. Subsequently, Lf-CMD-CS-CUR@Eu-MOF was synthesized using the Maillard reaction. Various spectral characterizations, drug entrapment, drug content, in vitro drug release, biocompatibility and cell cytotoxicity studies were performed. It exhibited an entrapment efficiency of 88.87 ± 2.1 %, a drug content of 3.45 ± 0.98 %, and a drug loading rate of 34.85 ± 0.6 mg/g. Furthermore, the Lf-CMD-CS-CUR@Eu-MOF exhibits excellent biocompatibility with normal cells. The in vitro dissolution study confirmed a release of 78.12 % of 'CUR' in pH 5.8 phosphate buffer (over 120 h), attributed to the controlled release rate by the 'CS' coating on the surface of CUR@Eu-MOF. The BEL-7402 cell line showed concentration-dependent toxicity of nanobioconjugate to cancerous cells. Therefore, when 'Lf' is surface-decorated onto an appropriate polymeric material, it gains the capability to function as a carrier for transporting 'CUR' to the precise target site within HPTC. In conclusion, Lf-CMD incorporated CS-coated Eu-MOF can provide a promising approach for targeted drug delivery in HPTC management.

Metal-Organic Framework (MOF)-A Universal Material for Biomedicine

Metal-organic frameworks (MOFs) are a very promising platform for applications in various industries. In recent years, a variety of methods have been developed for the preparation and modification of MOFs, providing a wide range of materials for different applications in life science. Despite the wide range of different MOFs in terms of properties/sizes/chemical nature, they have not found wide application in biomedical practices at present. In this review, we look at the main methods for the preparation of MOFs that can ensure biomedical applications. In addition, we also review the available options for tuning the key parameters, such as size, morphology, and porosity, which are crucial for the use of MOFs in biomedical systems. This review also analyses possible applications for MOFs of different natures. Their high porosity allows the use of MOFs as universal carriers for different therapeutic molecules in the human body. The wide range of chemical species involved in the synthesis of MOFs makes it possible to enhance targeting and prolongation, as well as to create delivery systems that are sensitive to various factors. In addition, we also highlight how injectable, oral, and even ocular delivery systems based on MOFs can be used. The possibility of using MOFs as therapeutic agents and sensitizers in photodynamic, photothermal, and sonodynamic therapy was also reviewed. MOFs have demonstrated high selectivity in various diagnostic systems, making them promising for future applications. The present review aims to systematize the main ways of modifying MOFs, as well as the biomedical applications of various systems based on MOFs.

Rapidly and ultra-sensitive colorimetric detection of H2O2 and glucose based on ferrous-metal organic framework with enhanced peroxidase-mimicking activity

In this article, a novel metal-organic framework, namely MIL-101(Fe^II), was firstly synthesized via a facile method. In the presence of H₂O₂, MIL-101(Fe^II) possesses excellent peroxidase-like activity toward the classical chromogenic substrate, N,N-Diethyl-p-phenylenediamine sulfate salt (DPD). The substitution of Fe²⁺ enhances the construction of Fe(II)-oxo nodes and accelerates electrons transfer between DPD and H₂O₂, thereby improving the peroxidase-mimicking catalytic activity of MIL-101(Fe^II) nanoenzyme. Additionally, DPD molecules could be adsorbed readily onto the surface of the nanoparticles due to the π-π interaction. The study of Michaelis constant indicates that the MIL-101(Fe^II) exhibits a higher affinity towards DPD (0.16 mM) in contrast to horseradish peroxidase (0.78 mM). In view of the impressive catalytic performance of MIL-101(Fe^II), two reliable monitoring platforms for the rapid detection of H₂O₂ and glucose were established with extremely low detection limits of 18.04 nM and 0.87 μM in the ranges of 40-5000 nM and 1.2-300 μM, respectively. The study of the catalytic mechanism indicates that DPD oxidation is attributed to the hydroxyl radical (·OH) produced from the decomposition of H₂O₂ catalyzed by MIL-101(Fe^II). Furthermore, the developed sensor indicates high selectivity and stability and can be effectively appropriate for the detection of H₂O₂ and glucose in real samples. This work not only provides a novel nanozyme with superior catalytic performance for biological analysis, but also broadens the application field of MIL-101(Fe^II) material.

Application of advanced technology in traditional Chinese medicine for cancer therapy

Although cancer has seriously threatened people’s health, it is also identified by the World Health Organization as a controllable, treatable and even curable chronic disease. Traditional Chinese medicine (TCM) has been extensively used to treat cancer due to its multiple targets, minimum side effects and potent therapeutic effects, and thus plays an important role in all stages of tumor therapy. With the continuous progress in cancer treatment, the overall efficacy of cancer therapy has been significantly improved, and the survival time of patients has been dramatically prolonged. In recent years, a series of advanced technologies, including nanotechnology, gene editing technology, real-time cell-based assay (RTCA) technology, and flow cytometry analysis technology, have been developed and applied to study TCM for cancer therapy, which efficiently improve the medicinal value of TCM and accelerate the research progress of TCM in cancer therapy. Therefore, the applications of these advanced technologies in TCM for cancer therapy are summarized in this review. We hope this review will provide a good guidance for TCM in cancer therapy.

Synthesis of NMOF-5 Using Microwave and Coating with Chitosan: A Smart Biocompatible pH-Responsive Nanocarrier for 6-Mercaptopurine Release on MCF-7 Cell Lines

Cancer is one of the most difficult diseases to treat, threatening the lives of millions of people today. So far, various methods have been used to treat cancer, each having its drawbacks. One of these methods is treatment with anticancer drugs, which unfortunately have severe side effects. One of the causes of these complications is the nonspecific effects of anticancer drugs, which attack normal cells in addition to cancer cells and damage healthy tissues. In this study, we are trying to reduce the side effects and increase the efficacy of the drug by providing smart drug delivery. The metal-organic framework (MOF) was rapidly synthesized using a microwave method and at the nanoscale. The particle size of NMOF-5 was 18-20 nm, and its surface area was 2690 m²·g^-1. A chitosan polymer coating was formed on the nanocarrier after 6-mercaptopurine was introduced. The biocompatible nanocarrier exhibited a high capacity to adsorb the drug. The biocompatible nanocarrier slowly and uniformly released 96.78% of the drug in a simulated solution at pH 5 and 20.52% at pH 7.4. This showed that CS-6-MP-NMOF-5 released the drug smartly and pH-sensitively. The stability of the biocompatible nanocarrier was studied at different pH values and remained stable at pH 5 for up to 48 h. The toxicity study of the MCF-7 cell line at different concentrations for 24 h showed the excellent performance of the biocompatible nanocarrier compared to the free drug in terms of toxicity to breast cancer cells.

Cobalt doped in Zn-MOF-5 nanoparticles to regulate tumor microenvironment for tumor chemo/chemodynamic therapy

Metal-organic frameworks are often used as a chemotherapeutic drug carrier due to their diverse metal sites and good acid degradation ability. Herein Co-doped Zn-MOF-5 nanoparticles with a high Co doping rate of 60% were synthesized for chemo-chemodynamic synergistic therapy of tumor. Co ions can mediate chemodynamic therapy through Fenton-like reaction and regulate the tumor microenvironment by consuming the reduced glutathione. The CoZn-MOF-5 shows high drug loading capacity with doxorubicin loading rate of 72.8%. The CoZn-MOF-5@PEG@DOX nanodrugs has a strong killing effect on 4T1 cancer cells, suggesting the chemo-chemodynamic synergistic effect on tumor therapy.

Novel zinc-silver nanocages for drug delivery and wound healing: Preparation, characterization and antimicrobial activities

Metal organic framework (MOF)-nanocages (MOF-NCs) in the form of zinc-based nanoparticles (NPs) were synthesized as drug carriers for the purpose of wound healing. The prepared NCs (single and bi-metallic with silver-MOF) were based on zinc and they were loaded with ascorbic acid (vitamin C) as a model drug which accelerates wound healing. The NCs were then investigated by several characterization techniques such as XRD, TEM, FTIR and BET surface area. Furthermore, the release behavior of the loaded ascorbic acid from the developed NCs was measured in phosphate buffer solution (PBS). NCs antibacterial activity was tested against strain of gram-positive bacteria (Staphylococcus aureus ATCC- 29213, Streptococcus pyogenes ATCC-19615 and Bacillus subtilis ATCC-6633), gram-negative bacteria strain (Pseudomonas aeruginosaATCC-27853and Escherichia coli ATCC-25922) and fungi (Candida albicans ATCC-10231).The physicochemical features of the NCs were confirmed by the results obtained from XRD and FTIR measurements. The particle size of the NCs was confirmed to be in the range of 30-50 nm. Prolonged drug release that was combined with impressive antibacterial activities, and good wound healing rates were also recognized for the zinc based NCs in comparison to commonly used Ag NPs. It is concluded that the current NCs are potentially suitable for wound healing and drug delivery applications.

Zr-based metal organic framework nanoparticles coated with a molecularly imprinted polymer for trace diazinon surface enhanced Raman scattering analysis

In this study, a new surface imprinted polymer of type MOFs-MIPs was synthesized with diazinon as template and Zr-based metal organic framework (UiO-67) as matrix for trace diazinon surface enhanced...

Design of Oleanolic Acid-based Hybrid Compounds as Potential Pharmaceutical Scaffolds

Background:

Infectious diseases, as well as cancer, are the leading causes of death worldwide. Drug resistance usually results in their treatment requiring a combination of two or more drugs.

Objective:

Oleanolic-based hybrid compounds were prepared via esterification and characterized using FTIR, NMR and LC-MS. In vitro antibacterial and in vitro cytotoxicity studies were performed.

Method:

Oleanolic acid was hybridized with selected known pharmaceutical scaffolds via the carboxylic acid functionality in order to develop therapeutics with increased biological activity. Antibacterial activity was determined using the micro-dilution assay against selected Gram-positive and Gram-negative bacteria and cytotoxicity using the sulforhodamine B assay.

Results:

Compound 8 displayed potent antibacterial effect against five strains of bacteria, such as Bacillus subtilis, Staphylococcus aureus, Proteus vulgaris, Klebsiella oxytoca, and Escherichia coli, with MIC values of 1.25, 0.078, 0.078, 1.25, 1.25 mg/mL when compared to the control, oleanolic acid (MIC = 2.5 mg/mL). Furthermore, in vitro cytotoxicity, as determined using the SRB assay, against selected cancer cells revealed that compound 7 was the most cytotoxic on MDA, DU145, and MCF-7 cell lines with IC50 values of 69.87 ± 1.04, 73.2 ± 1.08, and 85.27 ± 1.02 μg/mL, respectively, compared to oleanolic acid with an IC50 > 200 μg/mL.

Conclusion:

Hybridization of oleanolic acid was successful, and further development of these potential antibacterial compounds with reduced cytotoxicity is therefore warranted.

Optimization of the adsorption and removal of Sb(iii) by MIL-53(Fe)/GO using response surface methodology

In this study, a graphene oxide metal–organic framework (MIL-53(Fe)/GO) composite adsorbent was successfully synthesized using a simple method at room temperature.

Immune-regulating bimetallic metal-organic framework nanoparticles designed for cancer immunotherapy

Immunogenic cell death (ICD) is a promising strategy in cancer immunotherapy to induce high immunogenicity and activate the immune system. However, its efficacy is counteracted by the concurrent exposure of phosphatidylserine (PS), an immunosuppressive signal on the surface of cancer cells. Here we report the synthesis of a bimetallic metal-organic framework (MOF) nanoparticle containing Gd³⁺ and Zn²⁺ (Gd-MOF-5) that can be used as an immunomodulator to downregulate the immunosuppressive PS signal and an ICD inducer to upregulate immunostimulatory signals. Gd³⁺ inhibits PS externalization via inhibiting the activity of scramblase, an enzyme to transfer PS to the outer leaflet of plasma membrane. Moreover, intracellular Zn²⁺ overload activates endoplasmic reticulum stress for ICD induction. In combination with an immune checkpoint inhibitor (PD-L1 antibody, denoted as aPDL1), Gd-MOF-5 activated potent immune response and effectively inhibited primary and distal tumor growth in a bilateral 4T1 tumor model. This work presents a new strategy using designed MOF materials to modulate the cell signalling and immunosuppressive microenvironment to improve the outcome of cancer immunotherapy.

When metal-organic framework mediated smart drug delivery meets gastrointestinal cancers

Cancers of the gastrointestinal tract constitute one of the most common cancer types worldwide and a ∼58% increase in the global number of cases has been estimated by IARC for the next twenty years. Recent advances in drug delivery technologies have attracted scientific interest for developing and utilizing efficient therapeutic systems. The present review focuses on the use of nanoscale MOFs (Nano-MOFs) as carriers for drug delivery and imaging purposes. In pursuit of significant improvements to current gastrointestinal cancer chemotherapy regimens, systems that allow multiple concomitant therapeutic options (polytherapy) and controlled release are highly desirable. In this sense, MOF-based nanotherapeutics represent a significant step towards achieving this goal. Here, the current state-of-the-art of interdisciplinary research and novel developments into MOF-based gastrointestinal cancer therapy are highlighted and reviewed.

Metal-organic frameworks for advanced drug delivery

Metal-organic frameworks (MOFs), comprised of organic ligands and metal ions/metal clusters via coordinative bonds are highly porous, crystalline materials. Their tunable porosity, chemical composition, size and shape, and easy surface functionalization make this large family more and more popular for drug delivery. There is a growing interest over the last decades in the design of engineered MOFs with controlled sizes for a variety of biomedical applications. This article presents an overall review and perspectives of MOFs-based drug delivery systems (DDSs), starting with the MOFs classification adapted for DDSs based on the types of constituting metals and ligands. Then, the synthesis and characterization of MOFs for DDSs are developed, followed by the drug loading strategies, applications, biopharmaceutics and quality control. Importantly, a variety of representative applications of MOFs are detailed from a point of view of applications in pharmaceutics, diseases therapy and advanced DDSs. In particular, the biopharmaceutics and quality control of MOFs-based DDSs are summarized with critical issues to be addressed. Finally, challenges in MOFs development for DDSs are discussed, such as biostability, biosafety, biopharmaceutics and nomenclature.

γ-Cyclodextrin metal-organic framework as a carrier to deliver triptolide for the treatment of hepatocellular carcinoma

Triptolide (TPL) has been employed to treat hepatocellular carcinoma (HCC). However, the poor water solubility of TPL restricts its applications. Therefore, we prepared TPL-loaded cyclodextrin-based metal-organic framework (TPL@CD-MOF) to improve the solubility and bioavailability of TPL, thus enhancing the anti-tumor effect on HCC. The BET surface and the pore size of TPL@CD-MOF were 10.4 m²·g^-1 and 1.1 nm, respectively. The results of XRD indicated that TPL in TPL@CD-MOF was encapsuled. TPL@CD-MOF showed a slower release than free TPL in vitro. Moreover, the CD-MOF improved the bioavailability of TPL. TPL@CD-MOF showed slightly higher, but statistically significant, anti-tumor efficacy in vitro and in vivo compared to free TPL. In addition, TPL@CD-MOF exhibited a modest improvement of the anti-tumor effects, which may be associated to the enhanced in vivo absorption. Overall, these findings suggested the potential CD-MOF as oral drug delivery carriers for anti-tumor drugs. The process of TPL loading into CD-MOF and its enhanced oral bioavailability and anti-tumor activity.

Preparation and application of peptide molecularly imprinted material based on mesoporous metal-organic framework

In this study, a new molecularly imprinted material, MIP@UiO-66-NH₂, was synthesized with glutathione (GSH) as template and mesoporous metal organic framework (UiO-66-NH₂) as matrix. The molecularly imprinted polymer was modified on the surface and into the pores of the UiO-66-NH₂ by surface molecular imprinting method with thin polymer layer. Based on high specific surface area (1091.93 m² g^-1) and appropriate pore size (35 nm) of the ordered mesoporous UiO-66-NH₂, the adsorption capacity for GSH reached 94.43 mg g^-1, and the adsorption equilibrium could be achieved within 30 min. The adsorption isotherm data of MIP@UiO-66-NH₂ could be described well by Freundlich model and the kinetic data complied well with pseudo-second-order model. In addition, the MIP@UiO-66-NH₂ showed low adsorption capacity to GSH structural analogs (Q_L-cys = 6.51 mg g^-1), suggesting great selectivity for GSH recognition. Finally, the MIP@UiO-66-NH₂ was successfully applied for selective separation of GSH from BSA, skim milk and egg white tryptic digest.

A novel hybrid fluorescence probe sensor based on metal-organic framework@carbon quantum dots for the highly selective detection of 6-mercaptopurine

In the present study, MIL-101(Fe) and amine-carbon quantum dots (CQDs) were combined via a post-synthetic modification (PSM) method; thus, a novel MIL-101(Fe)@amine-CQD hybrid fluorescent probe sensor for the detection of 6-mercaptopurine (6-MP) was synthesized. Amine-CQDs as a fluorescent material can convert the bonding interaction between MIL-101(Fe) and 6-MP into recognizable fluorescence signals, and MIL-101 (Fe) as an adsorbent can pre-concentrate 6-MP. Hereupon, this new sensor demonstrates high selectivity and sensitivity towards the detection of 6-MP. The addition of 6-MP to this probe quenches the fluorescence signal at 599 nm. In this study, factors such as pH, response time, and concentration of MIL-101(Fe)@amine-CQDs were optimized by the one-factor-at-a-time (OFAT) method. Under optimal conditions, the relationship between the fluorescence enhancement factor and the concentration of 6-MP for this sensor in the range of 0.1667-1.0000 μg L^-1 was linear (R² = 0.9977, n = 3). The limit of detection and limit of quantitation were 55.70 ng L^-1 and 202.06 ng L^-1, respectively, which are better than similar techniques. The repeatability of intra-day and inter-day was 2.4% and 4.7%, respectively. This fluorescent sensor was employed to determine 6-MP in real samples and exhibited acceptable results.

Investigation of Metal-Organic Framework-5 (MOF-5) as an Antitumor Drug Oridonin Sustained Release Carrier

Oridonin (ORI) is a natural active ingredient with strong anticancer activity. But its clinical use is restricted due to its poor water solubility, short half-life, and low bioavailability. The aim of this study is to utilize the metal organic framework material MOF-5 to load ORI in order to improve its release characteristics and bioavailability. Herein, MOF-5 was synthesized by the solvothermal method and direct addition method, and characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), Thermogravimetric Analysis (TG), Brunauer-Emmett-Teller (BET), and Dynamic Light Scattering (DLS), respectively. MOF-5 prepared by the optimal synthesis method was selected for drug-loading and in vitro release experiments. HepG2 cells were model cells. MTT assay, 4',6-diamidino-2-phenylindole (DAPI) staining and Annexin V/PI assay were used to detect the biological safety of blank carriers and the anticancer activity of drug-loaded materials. The results showed that nano-MOF-5 prepared by the direct addition method had complete structure, uniform size and good biocompatibility, and was suitable as an ORI carrier. The drug loading of ORI@MOF-5 was 52.86% ± 0.59%. The sustained release effect was reliable, and the cumulative release rate was about 87% in 60 h. ORI@MOF-5 had significant cytotoxicity (IC50:22.99 μg/mL) and apoptosis effect on HepG2 cells. ORI@MOF-5 is hopeful to become a new anticancer sustained release preparation. MOF-5 has significant potential as a drug carrier material.

Metal Organic Framework Based Polymer Mixed Matrix Membranes: Review on Applications in Water Purification

Polymeric membranes have been widely employed for water purification applications. However, the trade-off issue between the selectivity and permeability has limited its use in various applications. Mixed matrix membranes (MMMs) were introduced to overcome this limitation and to enhance the properties and performance of polymeric membranes by incorporation of fillers such as silica and zeolites. Metal-organic frameworks (MOFs) are a new class of hybrid inorganic-organic materials that are introduced as novel fillers for incorporation in polymeric matrix to form composite membranes for different applications especially water desalination. A major advantage of MOFs over other inorganic fillers is the possibility of preparing different structures with different pore sizes and functionalities, which are designed especially for a targeted application. Different MMMs fabrication techniques have also been investigated to fabricate MMMs with pronounced properties for a specific application. Synthesis techniques include blending, layer-by-layer (LBL), gelatin-assisted seed growth and in situ growth that proved to give the most homogenous dispersion of MOFs within the organic matrix. It was found that the ideal filler loading of MOFs in different polymeric matrices is 10%, increasing the filler loading beyond this value led to formation of aggregates that significantly decreased the MOFs-MMMs performance. Despite the many merits of MOFs-MMMs, the main challenge facing the upscaling and wide commercial application of MOFs-MMMs is the difficult synthesis conditions of the MOFs itself and the stability and sustainability of MOFs-MMMs performance. Investigation of new MOFs and MOFs-MMMs synthesis techniques should be carried out for further industrial applications. Among these new synthesis methods, green MOFs synthesis has been highlighted as low cost, renewable, environmentally friendly and recyclable starting materials for MOFs-MMMs. This paper will focus on the investigation of the effect of different recently introduced MOFs on the performance of MOFs-MMMs in water purification applications.

Surface-defect-rich mesoporous NH2-MIL-125 (Ti)@Bi2MoO6 core-shell heterojunction with improved charge separation and enhanced visible-light-driven photocatalytic performance

Mesoporous NH₂-MIL-125(Ti)@Bi₂MoO₆ core-shell heterojunctions with surface defects were fabricated through a facile solvothermal method. The mesoporous core-shell structure with a large relative surface area of 87.7 m² g^-1 and narrow pore size of 8.2 nm extends the photoresponse to the range of visible light due to the narrow band gap of ∼1.89 eV. The visible-light-driven photocatalytic degradation efficiency of highly toxic dichlorophen and trichlorophenol were 93.28 and 92.19%, respectively, and the corresponding rate constants were approximately 8 and 17 times higher than the rates achieved by pristine NH₂-MIL-125(Ti). The photocatalytic oxygen production rate was increased to 171.3 µmol g^-1. Recycling for several cycles indicates high stability, which is favorable for practical applications. The excellent photocatalytic performance can be ascribed to the formation of the core-shell heterojunctions and to the surface defects that favor charge separation and visible light absorption; the mesoporous structure offers an adequate number of surface active sites and mass transfer. This novel mesoporous core-shell photocatalyst will have potential applications in the environment, and this strategy offers a new insight into fabrication of other high-performance core-shell structure photocatalysts.

Acrylic Acid-Functionalized Metal-Organic Frameworks for Sc(III) Selective Adsorption

The increasing demand for rare-earth elements (REEs) due to their extensive high-tech applications has encouraged the development of new sustainable approaches for REE recovery and separation. In this work, a series of acrylic acid-functionalized metal-organic framework materials (named as y-AA- x@MIL-101s) were prepared and used for selective adsorption of Sc(III). The adsorbent was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption, X-ray photoelectron spectroscopy, and zeta potential and surface functional-group titration. The adsorption isotherm and kinetics data were accurately described by the Langmuir and pseudo-second-order models. The adsorption capacity of the material for Sc(III), Nd(III), Gd(III), and Er(III) was 90.21, 104.59, 58.29, and 74.94 mg g^-1, respectively. Importantly, the adsorbent was better for selective recovery of Sc(III) not only from the 16 REE mixed system but also the Cu(II), Zn(II), Mn(II), Co(II), and Al(III) coexistence solution. Except for Sc(III), the material displayed high affinity for Nd(III) in the light rare-earth mixture and for Gd(III) in the middle rare-earth mixture. All in all, this study provides a new method for separation and recovery of REEs, which makes this work highly significant in separation and enrichment.