Activation of a gamma-cyclodextrin-based metal-organic framework using supercritical carbon dioxide for high-efficient delivery of honokiol

Cyclodextrin-based metal-organic frameworks transforming drug delivery

Cyclodextrin-based metal-organic frameworks (CD-MOFs) are gaining traction in the realm of drug delivery due to their inherent versatility and potential to amplify drug efficacy, specificity, and safety. This article explores the predominant preparation techniques for CD-MOFs, encompassing methods like vapor diffusion, microwave-assisted, and ultrasound hydrothermal approaches. Native CD-MOFs present compelling advantages in drug delivery applications. They can enhance drug loading capacity, stability, solubility, and bioavailability by engaging in diverse interactions with drugs, including host-guest, hydrogen bonding, and electrostatic interactions. Beyond their inherent properties, CD-MOFs can be customized as drug carriers through two primary strategies: co-crystallization with functional components and surface post-modifications. These tailored modifications pave the way for controlled release manners. They allow for slow and sustained drug release, as well as responsive releases triggered by various factors such as pH levels, glutathione concentrations, or specific cations. Furthermore, CD-MOFs facilitate targeted delivery strategies, like pulmonary or laryngeal delivery, enhancing drug delivery precision. Overall, the adaptability and modifiability of CD-MOFs underscore their potential as a versatile platform for drug delivery, presenting tailored solutions that cater to diverse biomedical and industrial needs.

Glutathione-responsive CD-MOFs co-loading honokiol and indocyanine green biomimetic active targeting to enhance photochemotherapy for breast cancer

Breast cancer has now replaced lung cancer as the most prevalent malignant tumor worldwide, posing a serious health risk to women. We have recently designed a promising option strategy for the treatment of breast cancer. In this work, cyclodextrin metal-organic frameworks with high drug-carrying properties were endo-crosslinked by 3,3'dithiodipropionyl chloride to form cubic phase gel nanoparticles, which were drug-loaded and then coated by MCF-7 cell membranes. After intravenous injection, this multifunctional nanomedicine achieved dramatically homologous targeting co-delivery of honokiol and indocyanine green to the breast tumor. Further, the disulfide bonds in the nanostructures achieved glutathione-responsive drug release, induced tumor cells to produce reactive oxygen species and promoted apoptosis, resulting in tumor necrosis, and at the same time, inhibited Ki67 protein expression, which enhanced photochemotherapy, and resulted in a 94.08 % in vivo tumor suppression rate in transplanted tumor-bearing mice. Thereby, this nanomimetic co-delivery system may have a place in breast cancer therapy due to its simple fabrication process, excellent biocompatibility, efficient targeted delivery of insoluble drugs, and enhanced photochemotherapy.

β-Cyclodextrin metal-organic framework as a green carrier to improve the dissolution, bioavailability, and liver protective effect of luteolin

The incidence of acetaminophen-induced liver injury has increased, but effective prevention methods are limited. Although luteolin has hepatoprotective activity, its low solubility and bioavailability limit its applications. Cyclodextrin metal-organic frameworks (CD-MOFs) possess 3D-network structures and large inner cavities, which make them excellent carriers of poorly soluble drugs. In this study, we used CD-MOFs as carriers to improve the dissolution of luteolin and assessed their antioxidant activity, bioavailability, and hepatoprotective effects. Luteolin was loaded into β-CD-MOF, γ-CD-MOF, β-CD, and γ-CD, and characterized by powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TGA). Our results showed that luteolin-β-CD-MOF was the most stable. The main driving forces were hydrogen bonds and van der Waals forces, as determined by molecular simulation. The loading capacity of luteolin-β-CD-MOF was 14.67 wt%. Compared to raw luteolin, luteolin-β-CD-MOF exhibited a 4.50-fold increase in dissolution and increased antioxidant activity in vitro. Luteolin-β-CD-MOF increased the bioavailability of luteolin by approximately 4.04- and 11.07-fold in healthy rats and liver injured rats induced by acetaminophen in vivo, respectively. As determined by biochemical analysis, luteolin-β-CD-MOF exhibited a better hepatoprotective effect than raw luteolin in rats with acetaminophen-induced liver injury. This study provides a new approach for preventing acetaminophen-mediated liver damage.

Sustained-Release Hydrogen-Powered Bilateral Microneedles Integrating CD-MOFs for In Situ Treating Allergic Rhinitis

Glucocorticoids are widely used for treating allergic rhinitis, but conventional intranasal administration encounters unfavorable nasal cilia clearance and nasal mucosal barrier. Herein, a bilateral microneedle patch is fabricated for delivering cyclodextrin-based metal-organic frameworks (CD-MOF) encapsulating dexamethasone (DXMS) and paeonol (Pae), while NaH particles are mounted on the basal part of each microneedle. By intranasal administration, the microneedles are propelled into the nasal mucosa by NaH-generated hydrogen and then swell to form a hydrogel for sustainedly releasing drugs. The DXMS/Pae combination is demonstrated to be superior to more than the twofold dose of DXMS alone for improving allergic rhinitis in rats. It involves reducing mast cell degranulation and modulating Treg/Th17 cell homeostasis, whereas inhibiting Th1 to Th2 differentiation is associated with regulating the GATA3/T-bet pathway, as well as repairing epithelial barrier function by increasing MUC1 and downregulating periostin. In addition, this delivery system modulates the lipid metabolism of the nasal mucosa. Notably, the newly designed device significantly enhances the drug's therapeutic effect, and NaH-generated hydrogen may have the potential adjunctive therapeutic effect. Collectively, such an emerging microneedle-mediated nasal drug delivery creates a new form for alleviating immune inflammation and contributes a promising solution to reduce clinical glucocorticoid abuse.

Synthesis of Nanosized γ-Cyclodextrin Metal-Organic Frameworks as Carriers of Limonene for Fresh-Cut Fruit Preservation Based on Polycaprolactone Nanofibers

To address the issue of bacterial growth on fresh-cut fruits, this paper reports the synthesis of nanosized γ-cyclodextrin metal-organic frameworks (CD-MOFs) using an ultrasound-assisted method and their application as carriers of limonene for antibacterial active packaging. The effects of the processing parameters on the morphology and crystallinity of the CD-MOFs are investigated, and the results prove that the addition of methanol is the key to producing nanosized CD-MOFs. The limonene loading content of the nanosized CD-MOFs can reach approximately 170 mg g-1. The sustained-release behaviors of limonene in the CD-MOFs are evaluated. Molecular docking simulations reveal the distribution and binding sites of limonene in the CD-MOFs. CD-MOFs are deposited on the surfaces of polycaprolactone (PCL) nanofibers via an immersion method, and limonene-loaded CD-MOF@PCL nanofibers are prepared. The morphology, crystallinity, thermal stability, mechanical properties, and antibacterial activity of the nanofibers are also studied. The nanofiber film effectively inhibits bacterial growth and prolongs the shelf life of fresh-cut apples. This study provides a novel strategy for developing antibacterial active packaging materials based on CD-MOFs and PCL nanofibers.

Multilayer Ti3 C2 -CNTs-Au Loaded with Cyclodextrin-MOF for Enhanced Selective Detection of Rutin

In this work, multi-layer Ti3 C2 - carbon nanotubes - gold nanoparticles (Ti3 C2 -CNTs-Au) and cyclodextrin metal-organic framework - carbon nanotubes (CD-MOF-CNTs) have been prepared by in situ growth method and used to construct the ultra-sensitive rutin electrochemical sensor for the first time. Among them, the large number of metal active sites of Ti3 C2 , the high electron transfer efficiency of CNTS, and the good catalytic properties of AuNPs significantly enhance the electrochemical properties of the composite carbon nanomaterials. Interestingly, CD-MOF has a unique host-guest recognition and a large number of cavities, molecular gaps, and surface reactive groups, which gives the composite outstanding accumulation properties and selectivity for rutin. Under the optimized conditions, the constructed novel sensor has satisfactory detection performance for rutin in the range of 2 × 10-9 to 8 × 10-7  M with a limit of detection of 6.5 × 10-10  M. In addition, the sensor exhibits amazing anti-interference performance against rutin in some flavonoid compounds and can be used to test natural plant samples (buckwheat, Cymbopogon distans, and flos sophorae immaturus). This work has promising applications in the field of environmental and food analysis, and exploring new directions for the application of Mxene-based composites.

Mechanism of multicyclic β-carotene impregnation into corn starch aerogels via supercritical CO2 with mathematical modeling

β-carotene, a natural dye renowned for its antioxidant and provitamin A activities, is hindered from direct use in food and drug products due to its susceptibility to oxidation, easy isomerization under light, heat, or acidic conditions, as well as its low water solubility and oral bioavailability. In this study, we addressed these challenges by loading β-carotene into corn starch aerogels via supercritical carbon dioxide (sc-CO2) and assessed its loading contributions through adsorption during contact time and precipitation during depressurization. The loading process was studied under two cycles at pressure of 30 MPa, temperature of 40 °C, depressurization rate of 0.4 MPa/min, and co-solvent (ethanol) mass percentage of 1.2 %. Experiments found adsorption minimally contributed to impregnation, while precipitation became the primary loading mechanism. The subsequent work focused on a mathematical model describing β-carotene loading into corn starch aerogels via precipitation, using the law of conservation of mass and classical nucleation theory. The model shows that using pure CO2 results in a loading efficiency of 0.10 mg β-carotene/g aerogel, while with CO2 and 1.2 % ethanol as the co-solvent, the loading efficiency increases threefold to 0.30 mg β-carotene/g aerogel.

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.

Chitosan-graft-poly(lactic acid)/CD-MOFs degradable composite microspheres for sustained release of curcumin

The solubility of cyclodextrin metal-organic frameworks (CD-MOFs) in aqueous media making it not suitable as sustained-release drug carrier. Here, curcumin-loaded CD-MOFs (CD-MOFs-Cur) was embedded in chitosan-graft-poly(lactic acid) (CS-LA) via a solid-in-oil-in-oil (s/o/o) emulsifying solvent evaporation method forming the sustained-release composite microspheres. At CS-LA concentration of 20 mg/mL, the composite microspheres showed good sphericity. The average particle size of CS-LA/CD-MOFs-Cur (2:1), CS-LA/CD-MOFs-Cur (4:1) and CS-LA/CD-MOFs-Cur (6:1) composite microspheres was about 9.3, 12.3 and 13.5 μm, respectively. The above composite microspheres exhibited various degradation rates and curcumin release rates. Treating in HCl solution (pH 1.2) for 120 min, the average particle size of above microspheres reduced 28.19 %, 24.34 % and 6.19 %, and curcumin released 86.23 %, 78.37 % and 52.57 %, respectively. Treating in PBS (pH 7.4) for 12 h, the average particle size of above microspheres reduced 30.56 %, 26.56 % and 10.66 %, and curcumin released 68.54 %, 54.32 % and 31.25 %, respectively. Moreover, the composite microspheres had a favorable cytocompatibility, with cell viability of higher than 90 %. These composite microspheres open novel opportunity for sustained drug release of CD-MOFs.

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.

Nanotechnology-Based Drug Delivery Systems for Honokiol: Enhancing Therapeutic Potential and Overcoming Limitations

Honokiol (HNK) is a small-molecule polyphenol that has garnered considerable attention due to its diverse pharmacological properties, including antitumor, anti-inflammatory, anti-bacterial, and anti-obesity effects. However, its clinical application is restricted by challenges such as low solubility, poor bioavailability, and rapid metabolism. To overcome these limitations, researchers have developed a variety of nano-formulations for HNK delivery. These nano-formulations offer advantages such as enhanced solubility, improved bioavailability, extended circulation time, and targeted drug delivery. However, existing reviews of HNK primarily focus on its clinical and pharmacological features, leaving a gap in the comprehensive evaluation of HNK delivery systems based on nanotechnology. This paper aims to bridge this gap by comprehensively reviewing different types of nanomaterials used for HNK delivery over the past 15 years. These materials encompass vesicle delivery systems, nanoparticles, polymer micelles, nanogels, and various other nanocarriers. The paper details various HNK nano-delivery strategies and summarizes their latest applications, development prospects, and future challenges. To compile this review, we conducted an extensive search using keywords such as "honokiol", "nanotechnology", and "drug delivery system" on reputable databases, including PubMed, Scopus, and Web of Science, covering the period from 2008 to 2023. Through this search, we identified and selected approximately 90 articles that met our specific criteria.

γ-Cyclodextrin Metal-Organic Frameworks: Do Solvents Make a Difference?

Conventionally, methanol is the solvent of choice in the synthesis of gamma-cyclodextrin metal-organic frameworks (γ-CD-MOFs), but using ethanol as a replacement could allow for a more food-grade synthesis condition. Therefore, the aim of the study was to compare the γ-CD-MOFs synthesised with both methanol and ethanol. The γ-CD-MOFs were characterised by scanning electron microscopy (SEM), surface area and pore measurement, Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD). The encapsulation efficiency (EE) and loading capacity (LC) of the γ-CD-MOFs were also determined for curcumin, using methanol, ethanol and a mixture of the two as encapsulation solvent. It was found that γ-CD-MOFs synthesised by methanol and ethanol do not differ greatly, the most significant difference being the larger crystal size of γ-CD-MOFs crystallised from ethanol. However, the change in solvent significantly influenced the EE and LC of the crystals. The higher solubility of curcumin in ethanol reduced interactions with the γ-CD-MOFs and resulted in lowered EE and LC. This suggests that different solvents should be used to deliberately manipulate the EE and LC of target compounds for better use of γ-CD-MOFs as their encapsulating and delivery agents.

Cyclodextrin-metal-organic frameworks in molecular delivery, detection, separation, and capture: An updated critical review

Metal-organic frameworks (MOFs) are coordination compounds with tuneable structures and controllable functions. However, the biological toxicity of traditional MOFs materials is often inevitable, making their application in the biological field have many limitations. Therefore, frontier research increasingly focuses on developing biocompatible MOFs materials. Cyclodextrins (CDs), derived from starch, are favored by various biomaterials due to their good biosafety and are often seen in the preparation and application of MOFs materials. This review describes the features of MOFs materials, and the various preparation methods of CD-MOFs are analyzed in detail from the perspective of CD classification. Additionally, the promising applications of CD-MOFs materials for delivery, detection, separation, and capture of active molecules in recent studies are systematically discussed and summarized. In terms of safety, the CD-MOFs materials are meticulously summarized. Finally, this review presents the challenges and future prospects regarding the current CD-MOFs-based materials, which will shed new light on the application of such materials in various fields.

Interactions between plant-derived antioxidants and cyclodextrins and their application for improving separation, detection, and food quality issues

Plant-derived antioxidants (PD-AOs) are important for food preservation, as well as for human health and nutrition. However, the poor chemical stability and water solubility of many PD-AOs currently limit their application as functional ingredients in foods and pharmaceuticals. Moreover, it is often difficult to isolate and detect specific antioxidants in multi-component systems, which again limits their potential in the food and medical industries. In this review, we highlight recent advances in the use of cyclodextrins (CDs) to overcome these limitations by forming simple, modified and competitive host-guest interactions with PD-AO. The host-guest properties of CDs can be used to enhance the separation efficiency of PD-AOs, as well as to improve their dispersion and stability in food systems. Moreover, the competitive complexation properties of CDs with target molecules can be used to selectively isolate PD-AOs from multi-component systems and develop detection technologies for PD-AOs. Overall, CD-antioxidant interactions have great potential for addressing isolation, detection, and food quality issues.

Cyclodextrin-based metal-organic framework nanoparticles as superior carriers for curcumin: Study of encapsulation mechanism, solubility, release kinetics, and antioxidative stability

In this paper, we propose a facile program of preparing nanoscale γ-cyclodextrin-based metal-organic frameworks (Nano-CD-MOFs) for the encapsulation of curcumin. Such Nano-CD-MOFs not only possess excellent mono-dispersity and crystalline structure, but also perform superior loading capacity. The results of N₂ adsorption-desorption, XRD, DSC, and microtopography are utilized to confirm the presence status of encapsulated curcumin and further reveal the encapsulation mechanism of Nano-CD-MOFs. Curcumin-loaded Nano-CD-MOFs (Cur-Nano-CD-MOFs) dramatically increase curcumin solubility and a top-down uniform dispersion in the dissolution process. The perfect fitting of First-order and Korsmeyer-Peppas models suggests that the release performance of Nano-CD-MOFs is controlled by the loaded quantity of curcumin and related to Fickian diffusion. Moreover, the antioxidative stability of Cur-Nano-CD-MOFs is considerably enhanced even after 120 min of persistent ultraviolet irradiation. Therefore, we suggest that such Nano-CD-MOFs can be promoted as an advanced carrier for the delivery of curcumin or other nutraceuticals.

Moisture-resistant and green cyclodextrin metal-organic framework nanozyme based on cross-linkage for visible detection of cellular hydrogen peroxide

A moisture-resistant and green cyclodextrin metal-organic framework (CD-MOF) nanosheet has been prepared via an one-pot antisolvent synthesis procedure. After the treatment of in situ chemical cross-linkage, the two-dimensional (2D) cross-linked CD-MOF exhibited both peroxidase (POD) and oxidase (OXD) enzymatic activities, as well as hydrolytic stability. On the basis of its POD mimics function, the proof-of-concept biosensors were constructed to realize the colorimetric detection for H₂O₂ and glucose, respectively. In vitro cytotoxicity experiments showed that the 2D cross-linked CD-MOF nanozymes still maintained excellent biocompatibility even at a concentration reaching up to several mg/mL. The in situ colorimetric detection of H₂O₂ secreted by HepG2 cells further confirmed its promising biocompatibility, showing its great promises as label-free colorimetric probe in early cancer detection and pathological process monitoring.

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.

Recent Advancements in MOF/Biomass and Bio-MOF Multifunctional Materials: A Review

Metal–organic frameworks (MOFs) and their derivatives have delivered perfect answers in detection, separation, solving water and electromagnetic pollution and improving catalysis and energy storage efficiency due to their advantages including their highly tunable porosity, structure and versatility. Recently, MOF/biomass, bio-MOFs and their derivatives have gradually become a shining star in the MOF family due to the improvement in the application performance of MOFs using biomass and biomolecules. However, current studies lack a systematic summary of the synthesis and advancements of MOF/biomass, bio-MOFs and their derivatives. In this review, we describe their research progress in detail from the following two aspects: (1) synthesis of MOF/biomass using biomass as a template to achieve good dispersion and connectivity at the same time; (2) preparing bio-MOFs by replacing traditional organic linkers with biomolecules to enhance the connection stability between metal ions/clusters and ligands and avoid the formation of toxic by-products. This enables MOFs to possess additional unique advantages, such as improved biocompatibility and mechanical strength, ideal reusability and stability and lower production costs. Most importantly, this is a further step towards green and sustainable development. Additionally, we showcase some typical application examples to show their great potential, including in the fields of environmental remediation, energy storage and electromagnetic wave absorption.

Simultaneous solubilization and extended release of insoluble drug as payload in highly soluble particles of γ-cyclodextrin metal-organic frameworks

The inclusion and nanocluster formed in cyclodextrin-metal organic framework (CD-MOF) make it a remarkable vehicle in improving the solubility and bioavailability of insoluble drugs, but rarely in elongation of drug release kinetics. In this research, an insoluble compound, 18β-glycyrrhetinic acid (GA), encapsulated in CD-MOF (GA@nano-CD-MOF) had prominent effects in the treatment of bleomycin-induced idiopathic pulmonary fibrosis in rats with an enhanced bioavailability by 6.8 times. The solubility of GA@nano-CD-MOF was 7780 times higher than that of GA, which was explained by the solubility parameter of amorphous cells constructed in silico simulation. CD-MOF imparted GA unique biphasic release kinetics, namely, GA released instantly to 52% and slowly released to 100% for a period of 5 days, which made the drug loaded particles much more flexible in pharmaceutical applications. The distribution of GA molecules in CD-MOF and drug loading priority obtained by molecular docking illustrated the formation of biphasic release mode at the molecular level combined with other characterizations of SEM, PXRD, TGA and DSC. In conclusion, CD-MOF has a unique effect to simultaneously solubilize an insoluble drug and extend its release for days as payload in highly soluble particles of γ-cyclodextrin metal-organic frameworks, which broaden the applications of drugs in specific treatment and then enhance the therapeutic effects.

Tumor-targeted delivery of honokiol via polysialic acid modified zein nanoparticles prevents breast cancer progression and metastasis

In this work, we developed polysialic acid (PSA) modified zein nanoparticles for targeted delivery of honokiol (HNK) to enhance drug delivery efficiency and specific biodistribution at tumor sites. The antisolvent precipitation and electrostatic interaction methods were employed to fabricate the PSA-Zein-HNK nanoparticles, which exhibited mean size of 107.2 ± 10.1 nm and HNK encapsulation efficiency of 79.2 ± 2.3%. The PSA-Zein-HNK maintained a uniform dispersion in serum for 48 h, implying the improved colloid stability of zein nanoparticles via PSA coating. The cellular uptake of PSA-Zein-Cou6 nanoparticles in 4 T1 cells was 2.58-fold higher than non-targeting Zein-Cou6. In addition, the IC₅₀ value at 48 h for PSA-Zein-HNK (4.37 μg/mL) was significantly higher than the Zein-HNK (7.74 μg/mL). Enhanced tumor accumulation of the PSA-Zein-HNK was confirmed in 4 T1 breast cancer-bearing mice by near-infrared fluorescence imaging, resulting in desirable antitumor efficacy and favorable biosafety. Besides, compared with non-targeting zein nanoparticles, the PSA-Zein-HNK achieved a higher tumor growth inhibition rate of 52.3%. In particular, the metastasis of breast cancer to the lung or liver was remarkably suppressed by PSA-Zein-HNK. Together, our results demonstrated that the PSA-Zein-HNK could be a potential tumor-targeted drug delivery strategy for efficient treatment of breast cancer.

Microneedle-Mediated Biomimetic Cyclodextrin Metal Organic Frameworks for Active Targeting and Treatment of Hypertrophic Scars

Due to the lack of a delivery system that actively targets hypertrophic scar fibroblasts (HSFs), it is difficult to concentrate the effects of drugs on hypertrophic scars (HSs). We recently discovered that the HSF membrane has a homologous targeting effect and developed an active targeted drug delivery system for the local treatment of HSs. A diphenyl carbonate cross-linked cyclodextrin metal organic framework (CDF) containing more than 26% (w/w) quercetin (QUE) was coated with a HSF membrane (QUE@HSF/CDF) and then dispersed in Bletilla striata polysaccharide (BSP)-fabricated dissolvable microneedles (BSP-MNs-QUE@HSF/CDF) for local administration. This biomimetic nanodrug delivery system improved efficacy on HSs by regulating Wnt/β-catenin and JAK2/STAT3 pathways and reducing the expression of collagens I and III in HS, and this performance was superior to those of systems without HSF functionalization or the assistance of microneedles. Additionally, we found that BSP has synergistic effects and the microneedles have higher mechanical strength and better physical stability than microneedles made of hyaluronic acid. This currently designed drug delivery strategy integrating biomimetic nanoparticles and dissolvable microneedles is promising for applications in the fields of skin disease treatment and cosmetics.

Precision release systems of food bioactive compounds based on metal-organic frameworks: synthesis, mechanisms and recent applications

Controlled release (CR) systems have become a powerful platform for accurate and effective delivery of bioactive compounds (BCs). Metal-organic frameworks (MOFs) are one of the best BCs-loaded carriers for CR systems. In the review, the principles and methods of the design and synthesis of MOFs-CR systems are summarized in detail, the encapsulation of BCs by MOFs and CR mechanisms are explored, and their biological toxicity and biocompatibility are highlighted and applications in the food industry are discussed. In addition, current challenges in this field and possible future development directions are also presented. MOFs have been proven to encapsulate BCs effectively, including gaseous and solid molecules, and control the release of BCs through spontaneous diffusion or stimulus-response. The solubility, stability and biocompatibility of BCs encapsulated by MOFs are greatly improved, which expands their applications in foods. The effective CR of BCs by MOFs-CR systems is beneficial to assist in maintaining or even improving the quality and safety of food, reduce the BCs usage while increasing the bioavailability. Low- or non-biotoxic MOFs, especially bio-MOFs, show greater application prospects in the food industry.

Encapsulation of curcumin in CD-MOFs: promoting its incorporation into water-based products and consumption

Curcumin has received considerable interest in functional food areas due to its variety of biological effects. However, its utilization is often limited by its insolubility and instability in aqueous solutions. Herein, curcumin was encapsulated in γ-cyclodextrin metal-organic frameworks (CD-MOFs) to achieve immediate release and rapid dissolution in water just by gentle stirring due to the dissociation of CD-MOFs. The released curcumin exhibited remarkably enhanced stability compared to its free form in aqueous solutions due to the inclusion effects of cyclodextrins. Besides, the impacts of temperature, light and gastrointestinal pH on the chemical stability of curcumin released from basic and neutral CD-MOFs were compared. The molar ratios of curcumin : γ-CD in basic CD-MOFs and neutral CD-MOFs were 1 : 1.7 and 1 : 9.8, respectively. Neutral CD-MOFs were more effective in retarding thermal and gastrointestinal degradation of curcumin because all curcumin molecules can form inclusion complexes with cyclodextrin. Basic CD-MOFs were more conducive to prolonging the half-life time of curcumin during photodegradation since its alkalinity darkened the color of curcumin solution causing lower light transmittance. Moreover, CD-MOFs exhibited higher loading and stability of curcumin due to their unique host-guest structure, than their pure cyclodextrin inclusion complex. Curcumin-loaded CD-MOFs having a fast-dissolving ability accompanied by the improved amorphous form stability of curcumin hold great potential as functional additives in instant food.

Recent Advances of Porous Materials Based on Cyclodextrin

Porous materials have attracted significant attention because of their rising applications in many fields. Cyclodextrins (CDs) are suitable building units in the fabrication of porous materials owing to their intrinsic nanoporous structure, easy modification, and biocompatibility, which may result in the formation of CD-based organic frameworks (including cyclodextrin metal-organic frameworks (CD-MOFs) and cyclodextrin covalent organic frameworks (CD-COFs)), and CD-based polymer hybrid porous materials. This review focuses on the recent progress in the fabrication and applications of CD-based porous materials with novel structures and functionalities.

Role of supercritical carbon dioxide (scCO2) in fabrication of inorganic-based materials: a green and unique route

In recent times, the supercritical carbon dioxide (scCO₂) process has attracted increasing attention in fabricating diverse materials due to the attractive features of environmentally benign nature and economically promising character. Owing to these unique characteristics and high-penetrability, as well as diffusivity conditions of scCO₂, this high-pressure technology, with mild operation conditions, cost-effective, and non-toxic, among others, is often applied to fabricate various organic and inorganic-based materials, resulting in the unique crystal architectures (amorphous, crystalline, and heterojunction), tunable architectures (nanoparticles, nanosheets, and aerogels) for diverse applications. In this review, we give an emphasis on the fabrication of various inorganic-based materials, highlighting the recent research on the driving factors for improving the quality of fabrication in scCO₂, procedures for production and dispersion in scCO₂, as well as common indicators utilized to assess quality and processing ability of materials. Next, we highlight the effects of specific properties of scCO₂ towards synthesizing the highly functional inorganic-based nanomaterials. Finally, we summarize this compilation with interesting perspectives, aiming to arouse a more comprehensive utilization of scCO₂ to broaden the horizon in exploring the green/eco-friendly processing of such versatile inorganic-based materials. Together, we firmly believe that this compilation endeavors to disclose the latent capability and universal prevalence of scCO₂ in the synthesis and processing of inorganic-based materials.

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.

Supercritical Carbon Dioxide as a Green Alternative to Achieve Drug Complexation with Cyclodextrins

Cyclodextrins are widely used in pharmaceutics to enhance the bioavailability of many drugs. Conventional drug/cyclodextrin complexation techniques suffer from many drawbacks, such as a high residual content of toxic solvents in the formulations, the degradation of heat labile drugs and the difficulty in controlling the size and morphology of the product particles. These can be overcome by supercritical fluid technology thanks to the outstanding properties of supercritical CO₂ (scCO₂) such as its mild critical point, its tunable solvent power, and the absence of solvent residue after depressurization. In this work the use of scCO₂ as an unconventional medium to achieve the complexation with native and substituted cyclodextrins of over 50 drugs, which belong to different classes, are reviewed. This can be achieved with different approaches such as the “supercritical solvent impregnation” and “particle-formation” techniques. The different techniques are discussed to point out how they affect the complexation mechanism and efficiency, the physical state of the drug as well as the particle size distribution and morphology, which finally condition the release kinetics and drug bioavailability. When applicable, the results obtained for the same drug with various cyclodextrins, or different complexation techniques are compared with those obtained with conventional approaches.

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.

Cyclodextrin Metal-Organic Frameworks and Their Applications

Cyclodextrin-based metal-organic frameworks (CD-MOFs), derived from γ-cyclodextrin (γ-CD) and alkali metal cations, constitute a class of porous, renewable, and edible MOFs that can be synthesized from a naturally occurring carbohydrate on a large scale. γ-CD is a C₈-symmetrical cyclic oligosaccharide composed of eight asymmetric α-1,4-linked d-glucopyranosyl residues that possesses a bucket-shaped cavity with an inner diameter of ∼1 nm and a depth of ∼0.8 nm. Upon combination of 1 equiv of γ-CD with 8 equiv of potassium hydroxide in an aqueous solution, followed by vapor diffusion of MeOH (or EtOH) into this solution during several days, CD-MOF-1 is obtained as cubic crystals. This carbohydrate-based MOF, which was discovered serendipitously in 2010, was the first highly crystalline CD-MOF to be obtained. X-ray crystallography of a single crystal reveals that it adopts the space group I432 with unit cell dimensions of approximately 31 × 31 × 31 ų. Other CD-MOFs, namely, CD-MOF-2 and CD-MOF-3, can be obtained when potassium ions are replaced by rubidium and cesium ions, respectively. CD-MOFs comprise extended body-centered frameworks of (γ-CD)₆ cubic units, which contain spherical pores that reside at the center of the cubes, interconnected by alkali metal cations, forming both cylindrical and triangular channels.During the past decade, CD-MOFs have emerged as a useful class of multifunctional materials based on porous frameworks with extended structures displaying robust crystallinity, permanent porosity, and excellent biocompatibility. The family of CD-MOFs has been joined by a growing collection of metal nodes involving alkali metal cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) and γ-CD as well as its derivatives. As a result of the ability of their extended porous frameworks to absorb guest molecules, including gases, drugs, metal-based nanoclusters, and nanoparticles, CD-MOFs have potential applications in areas as disparate as templating syntheses of metal-based nanoparticles and gels, adsorption and separation, trapping highly reactive intermediates, catalyst supports, sensing, electrical memory, and drug delivery.In this Account, we tell the story of CD-MOFs, a scientific discovery made in our research laboratory at Northwestern University, and the opportunities to use these environmentally friendly porous materials across different fields of science and technology. The story includes representative synthetic protocols for the preparation of CD-MOFs, along with an overview of their structural features, functionalization, and chemical modification aimed at increasing their stabilities in aqueous environments, and finally, a summary of their applications. The examples we will discuss, however, are only illustrative, and there is a significant body of additional findings emanating from our laboratory and others, especially in the realm of developing new synthetic strategies, tuning the framework stabilities, and exploring the guest inclusion and emergent properties of CD-MOFs. We refer readers to the original communications, papers, and reviews cited herein. We hope that, in the telling of the story of CD-MOFs, this Account may promote new scientific discoveries and further development of CD-MOF-based technologies in the future.

Targeted delivery of honokiol by zein/hyaluronic acid core-shell nanoparticles to suppress breast cancer growth and metastasis

Based on the antisolvent and electrostatic deposition methods, we fabricated zein/hyaluronic acid core-shell nanoparticles loaded with honokiol (HA-Zein-HNK), which could target delivery and enhance the therapeutic effect of the HNK. The prepared nanoparticles were found to have a mean size of 210.4 nm and negative surface charge. The HA-Zein-HNK nanoparticles exhibited improved antiproliferative and pro-apoptotic activities against 4T1 cells. Of note, the wound healing and transwell assessments indicated that the migration and invasion of 4T1 cells were markedly weakened by HA-Zein-HNK. Mechanistic insights revealed that HA-Zein-HNK downregulated the expressions of Vimentin and upregulated the expressions of E-cadherin. More importantly, an in vivo tissue distribution study demonstrated the excellent tumor target ability of HA-Zein. And these results correspond with the superior therapeutic efficacy of HA-Zein-HNK in 4T1 tumor bearing mice. In conclusion, we believe that HA-Zein nanoparticles may be served as a promising HNK delivery carrier for metastatic breast cancer therapy.