Recent Advances of Porous Materials Based on Cyclodextrin

Cyclodextrin reduced Fe(III) nanozyme-based colorimetric and photothermal dual-mode assay for early monitoring meat freshness by sensitive detection of hypoxanthine

A simple and sensitive method for monitoring the freshness of meat products is crucial for safeguarding food hygiene and human health. Here, we synthesized an environmentally friendly β-CD@Fe nanozyme through a one-pot solvothermal method, enabling colorimetric and photothermal dual-mode detection of hypoxanthine (Hx). In the xanthine oxidase (XOD)/nanozyme enzymatic cascade system, Hx ultimately led to the oxidation of colorless TMB to blue oxTMB, accompanied by enhanced absorbance at 652 nm and an increased temperature under 808 nm laser irradiation. The proposed dual-mode assay for Hx exhibited a good linear relationship in the range of 1-40 μM, achieving low detection limits of 0.29 μM (colorimetric) and 1.0 μM (photothermal), respectively. The β-CD@Fe nanozyme, characterized by its environmental friendliness, mild synthesis conditions, and high peroxidase-like activity, was successfully applied for the sensitive analysis of Hx in actual meat samples. This advancement offers promising potential for applications in food safety supervision.

One pot preparation of magnetic benzylated cyclodextrin-based hyper-cross-linked polymer for phthalate esters extraction from tea beverages

The increasing popularity of packaged beverages has raised concerns about the health risks associated with phthalate esters (PAEs), which are commonly found in plastics used for packaging. This study presents an eco-friendly approach for synthesizing a magnetic benzylated cyclodextrin-based hyper-cross-linked polymer (Fe3O4/BnCD-HCPP), in which FeCl3serves both as a catalyst for the Friedel-Crafts reaction and as an iron source for Fe3O4 nanoparticles. The Fe3O4/BnCD-HCPP composite was used as an adsorbent to extract of PAEs from tea beverages via magnetic solid-phase extraction, followed by gas chromatography-mass spectrometry analysis. The optimized method exhibited excellent sensitivity, with limits of detection ranging from 0.1 to 0.5 μg L-1. Additionally, the method achieved high recovery rates, ranging from 81.5 % to 118.5 %, and demonstrated precision (relative standard deviations <11.6 %) for PAEs spiked into tea beverages. Mechanistic studies indicated that the high extraction efficiency of Fe3O4/BnCD-HCPP for PAEs is due to its favorable pore size distribution, large specific surface area, and multiple interactions, including π-π stacking, hydrophobic force, and host-guest inclusion. This research not only provides an effective method for determining PAEs in complex aqueous matrices but also introduces a novel and sustainable approach for the fabrication of magnetic composites.

A non-interpenetrated mesoporous hydrogen-bonded organic framework constructed with 1,3,5-tri(4-carboxyphenyl)benzene

The discovery of porous molecular solids has been constantly hindered by phase transformation and interpenetration. Here, we crystallize two molecules with three substituted carboxylic groups. A mesoporous, non-interpenetrated HOF that is constructed from 1,3,5-tri(4-carboxyphenyl)benzene (TCPB) is discovered and reported for the first time.

Porphyrin-Based Metal-Organic Framework Photocatalysts: Structure, Mechanism and Applications

In recent years, porphyrins have been frequently reported as photocatalysts due to their fascinating photochemical properties. However, porphyrins have the same shortcomings as other homogeneous photocatalysts, such as poor stability and difficulty in recovering. To solve this problem, it is a good strategy to form a porphyrin-based metal-organic framework (PMOF) by modifying porphyrin functional groups and adding metals as nodes to connect and control the arrangement of porphyrins. The metal nodes control the rigidity and connectivity of the porphyrin modules to order them in the MOF, which improves the stability of the porphyrins, avoids porphyrin aggregation and folding, and increases the active sites for photocatalytic reactions. This review summarized the research progress of PMOF photocatalysts in the last ten years and analyzed the effects of the spatial structure, porphyrin ligands, porphyrin central metals, and metal nodes of PMOF on the photocatalytic performance. The applications of PMOF-based photocatalysts in H2 production, CO2 reduction, pollutant degradation, and sterilization are reviewed. In addition, the mechanism of these processes is described in detail. Finally, some suggestions on the development of PMOF photocatalysts are put forward.

Cyclodextrin supramolecular assembly confined luminescent materials

The macrocyclic supramolecular assembly confinement effect not only induces or extends the fluorescence/phosphorescence luminescence behavior of guest molecules but has also been widely applied in the research fields of chemistry, biology, and materials. This review primarily describes recent advances in cyclodextrin (CD) supramolecular assembly confined luminescent materials. Taking advantage of their hydrophobic cavity, CDs and their derivatives effectively encapsulate guest molecules and special functional groups or further assemble and polymerize to restrict the motion of guest chromophores, inducing and enhancing the luminescence behavior and realizing intelligent stimulus-responsive luminescence depending on changes in temperature, light, redox reactions and solvent polarity, which are successfully applied in targeted cell imaging, sensing, information encryption, anti-counterfeiting and flexible electronic light-emitting devices. With the emergence of new chromophores and CD primitives, spatial confinement within CD supramolecular assemblies will further realize the rapid development of supramolecular science and technology in circularly polarized luminescence, fluorescence/phosphorescence cascade energy transfer, light-harvesting energy-transfer systems and long persistent luminescent materials.

Removal of contaminants present in water and wastewater by cyclodextrin-based adsorbents: A bibliometric review from 1993 to 2022

Cyclodextrin (CD), a cyclic oligosaccharide from enzymatic starch breakdown, plays a crucial role in pharmaceuticals, food, agriculture, textiles, biotechnology, chemicals, and environmental applications, including water and wastewater treatment. In this study, a statistical analysis was performed using VOSviewer and Citespace to scrutinize 2038 articles published from 1993 to 2022. The investigation unveiled a notable upsurge in pertinent articles and citation counts, with China and USA contributing the highest publication volumes. The prevailing research focus predominantly revolves around the application of CD-based materials used as adsorbents to remove conventional contaminants such as dyes and metals. The CD chemistry allows the construction of materials with various architectures, including cross-linked, grafted, hybrid or supported systems. The main adsorbents are cross-linked CD polymers, including nanosponges, fibres and hybrid composites. Additionally, research efforts are actually concentrated on the synthesis of CD-based membranes, CD@graphene oxide, and CD@TiO2. These materials are proposed as adsorbents to remove emerging pollutants. By employing bibliometric analysis, this study delivers a comprehensive retrospective review and synthesis of research concerning CD-based adsorbents for the removal of contaminants from wastewater, thereby offering valuable insights for future large-scale application of CD-based adsorption materials.

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.

Synthesis of γ-Cyclodextrin-Reduced Fe(III) Nanoparticles with Peroxidase-like Catalytic Activity for Bacteriostasis of Food

Foodborne pathogens are a primary cause of human foodborne illness, making it imperative to explore novel antibacterial strategies for their control. In this study, Fe-γ-CD was successfully synthesized as a food antibacterial agent for use in milk and orange juice. The Fe-γ-CD consists of 6/11 Fe(II) and 5/11 Fe(III), which catalyze a Fenton-like catalytic reaction with H2O2 to generate •OH. Consequently, Fe-γ-CD exhibits exceptional peroxidase-like activity and broad-spectrum antibacterial efficacy. Fe-γ-CD not only disrupts the wall structure of ESBL-E. coli but also induces protein leakage and genetic destruction, ultimately leading to its death. Furthermore, Fe-γ-CD inhibits biofilm formation by MRSA and eradicates mature biofilms, resulting in MRSA's demise. Importantly, Fe-γ-CD demonstrates negligible cytotoxicity toward normal mammalian cells, making it an ideal candidate for application as an antibacterial agent in foodstuffs. These findings highlight that Fe-γ-CD is an effective tool for combating the spread of foodborne pathogens and food safety.

Enhancing propellant performance through intermolecular interactions: cyclodextrin-based MOF loading in nitrocellulose

Metal-organic frameworks (MOFs) offer promising opportunities for modifying energetic materials due to their micro-porous structure and high performance. In this study, we present a novel green MOF named cyclodextrin-MOF (CD-MOF), which incorporates potassium ions, synthesized using a simple methanol vapor diffusion approach. The CD-MOF incorporates potassium ions and enhances propellant performance through intermolecular force optimization with nitrocellulose (NC). Molecular dynamics simulations reveal stronger interactions between the CD-MOF and NC. The loading of the CD-MOF within NC forms a stable structure with resistance to migration and defense against crystalline precipitation and water absorption. Notably, in static combustion and pyrolysis tests, the CD-MOF exhibits efficient flame and flash inhibition. The thermal degradation and cauterization of the CD-MOF resulted in the formation of a complex microporous material capable of absorbing flammable and harmful gases such as CO, NO, NO2, and N2O. These findings shed light on the superior performance of the CD-MOF compared to conventional inorganic salts, and the comprehensive characterization and molecular simulations provide insights into the unique properties and applications of the CD-MOF, emphasizing its significant contribution to the field of green propellants.

Promoter-Controlled Synthesis and Conformational Analysis of Cyclic Mannosides up to a 32-mer

Cyclodextrins are widely used as carriers of small molecules for drug delivery owing to their remarkable host properties and excellent biocompatibility. However, cyclic oligosaccharides with different sizes and shapes are limited. Cycloglycosylation of ultra-large bifunctional saccharide precursors is challenging due to the constrained conformational spaces. Herein we report a promoter-controlled cycloglycosylation approach for the synthesis of cyclic α-(1→6)-linked mannosides up to a 32-mer. Cycloglycosylation of the bifunctional thioglycosides and (Z)-ynenoates was found to be highly dependent on the promoters. In particular, a sufficient amount of a gold(I) complex played a key role in the proper preorganization of the ultra-large cyclic transition state, providing a cyclic 32-mer polymannoside, which represents the largest synthetic cyclic polysaccharide to date. NMR experiments and a computational study revealed that the cyclic 2-mer, 4-mer, 8-mer, 16-mer, and 32-mer mannosides adopted different conformational states and shapes.

Supramolecular nanomedicines based on host-guest interactions of cyclodextrins

In the biomedical and pharmaceutical fields, cyclodextrin (CD) is undoubtedly one of the most frequently used macrocyclic compounds as the host molecule because it has good biocompatibility and can increase the solubility, bioavailability, and stability of hydrophobic drug guests. In this review, we generalized the unique properties of CDs, CD-related supramolecular nanocarriers, supramolecular controlled release systems, and targeting systems based on CDs, and introduced the paradigms of these nanomedicines. In addition, we also discussed the prospects and challenges of CD-based supramolecular nanomedicines to facilitate the development and clinical translation of these nanomedicines.

Regularities of Encapsulation of Tolfenamic Acid and Some Other Non-Steroidal Anti-Inflammatory Drugs in Metal-Organic Framework Based on γ-Cyclodextrin

Metal-organic frameworks based on cyclodextrins (CDs) have been proposed as promising drug delivery systems due to their large surface area, variable pore size, and biocompatibility. In the current work, we investigated an incorporation of tolfenamic acid (TA), a representative of non-steroidal anti-inflammatory drugs (NSAIDs), in a metal-organic framework based on γ-cyclodextrin and potassium cations (γCD-MOF). Composites γCD-MOF/TA obtained by absorption and co-crystallization methods were characterized using powder X-ray diffraction, low temperature nitrogen adsorption/desorption, scanning electron microscopy, and FTIR spectroscopy. It was demonstrated that TA loaded in γCD-MOF has an improved dissolution profile. However, the inclusion of TA in γ-CD reduces the membrane permeability of the drug. A comparative analysis of the encapsulation of different NSAIDs in γCD-MOF was performed. The impact of NSAID structure on the loading capacity was considered for the first time. It was revealed that the presence of heterocycles in the structure and drug lipophilicity influence the loading efficiency of NSAIDs in γCD-MOF.

In-situ Polymerization and Flame Retardant Mechanism of Bio-based Nitrogen and Phosphorus Macromolecular Flame Retardant in Plywood

To improve the flame retardant performance of the plywood and reduce the reagent loss and moisture absorption of the flame retardant, the bio-based supramolecular flame retardant has been prepared by vacuum-pressure impregnation and high-temperature in-situ polymerization in plywood. The best value of bonding strength appears at 170 ℃, and the LOI of 170BF-B plywood is 42.3%. After hot pressing, the moisture absorption rate of 170BF-B veneer is only 18.51%, while the loss resistance rate achieves 83.45%. Its residue at 700 ℃ is 91.36% higher than that of poplar veneer. In the combustion process, the PHRR and HRR of 170BF-B plywood are only 10.69% and 37.11% of that of untreated plywood. After combustion, an intumescent flame retardant layer exhibits a graphitization trend. In the flame retardant layer, there are not only functional groups, such as P = O, PO₄ ^3- , P-O-C decomposed by flame retardant but also characteristic functional groups of wood fiber, like C = O, C-H, etc. The prepolymer BF-B, which is composed of phytic acid, urea and, dicyandiamide polymerized with chitosan or lignocellulose to form a supramolecular flame retardant connected with P-O-C and P-O-N functional groups, thus improving the flame retardant and anti-loss property by in-situ polymerization. This article is protected by copyright. All rights reserved.

Polyoxometalate-Containing Supramolecular Gels

Supramolecular gels are important soft materials with various applications, which are fabricated through hydrogen bonding, π-π stacking, electrostatic or host-guest interactions. Introducing functional groups, especially inorganic components, is an efficient strategy to obtain gels with robust architecture and high performance. Polyoxometalates (POMs), as a class of negatively-charged clusters, have defined structures and multiple interaction sites, resulting in their potential as building blocks for constructing POM-containing supramolecular gels. The introduction of POMs into gels not only provides strong driving forces for the formation of gels due to the characteristics of charged cluster and oxygen-rich surface, but also brings new properties sourcing from unique electronic structures of POMs. Though many POM-containing gels have been reported, a comprehensive review is still absent. Herein, the concept of POM-containing gels is discussed, following with the design strategies and driving forces. To better understand the results in the literature, detailed examples, which are classified into several categories based on the types of organic components, are presented to illustrate the gelation process and gel structures. Moreover, applications of POM-containing gels in energy chemistry, sustainable chemistry and other aspects are also reviewed, as well as the future developments of this field. This article is protected by copyright. All rights reserved.