Host-guest Interactions Research Articles

Engineering pore limiting diameter of metal–organic frameworks for benchmark separation of mono- and di-branched hexane isomers

The separation of mono- and di-branched hexane isomers remains an important and challenging industrial process for the production of high-octane gasoline. Suitable adsorbents with high adsorption selectivity and capacity are urgently required. Herein, we demonstrate a strategy to realize highly efficient kinetically controlled hexane isomers adsorption separation that utilizes the tunability of the pore limiting diameter in M2TTFTB (M=Zn, Mn, Cd) by metal substitution. The appropriate refinement of the partially contracted pore not only improved the kinetic selectivities, but also enhanced the host–guest interaction and increased the adsorption capacity of 3MP and nHEX. The resulting Mn2TTFTB brought about both the record capacity of 3MP and the record kinetic selectivities of 3MP/22DMB and nHEX/22DMB, exhibiting the largest productivity of high-purity 22DMB in the breakthrough experiments, which sets a new benchmark for the hexane isomers separation via a rarely reported kinetically controlled mechanism.

Recent Progress of Supramolecular Chemotherapy Based on Host-Guest Interactions.

Chemotherapy is widely recognized as an effective approach for treating cancer due to its ability to eliminate cancer cells using chemotherapeutic drugs. However, traditional chemotherapy suffers from various drawbacks, including limited solubility and stability of drugs, severe side effects, low bioavailability, drug resistance, and challenges in tracking treatment efficacy. These limitations greatly hinder its widespread clinical application. In contrast, supramolecular chemotherapy, which relies on host-guest interactions, presents a promising alternative by offering highly efficient and minimally toxic anticancer drug delivery. In this review, an overview of recent advancements in supramolecular chemotherapy based on host-guest interactions is provided. The significant role it plays in guiding cancer therapy is emphasized. Drawing on a wealth of cutting-edge research, herein, a timely and valuable resource for individuals interested in the field of supramolecular chemotherapy or cancer therapy, is presented. Furthermore, this review contributes to the progression of the field of supramolecular chemotherapy toward clinical application.

Unraveling the molecular mechanism of the interaction between cyclodextrin-based nanoparticles (CDNPs) and paroxetine hydrochloride

Abstract Cyclodextrin-based nanoparticles (CDNPs) have shown promise as versatile carriers for improving drug delivery systems. This study investigates the binding constants governing the interaction between paroxetine hydrochloride (PRX) and β-cyclodextrin (βCD) and β-cyclodextrin epichlorohydrin polymer (βCDNP), utilizing a range of methodologies. The findings demonstrate enhanced binding affinity between PRX and βCDNP, offering insights into the binding behavior. Furthermore, the presence of a 2:1 βCD-PRX inclusion complex within the polymer suggests potential applications in drug delivery, particularly for improving solubility and stability of poorly water-soluble drugs. These results contribute to our understanding of host-guest interactions, with implications for enhancing therapeutic efficacy and patient outcomes. The study offers valuable insights into supramolecular chemistry and pharmaceutical sciences, paving the way for more effective drug delivery systems.

Benchmarking ANI potentials as a rescoring function and screening FDA drugs for SARS-CoV-2 Mpro

Here, we introduce the use of ANI-ML potentials as a rescoring function in the host–guest interaction in molecular docking. Our results show that the “docking power” of ANI potentials can compete with the current scoring functions at the same level of computational cost. Benchmarking studies on CASF-2016 dataset showed that ANI is ranked in the top 5 scoring functions among the other 34 tested. In particular, the ANI predicted interaction energies when used in conjunction with GOLD-PLP scoring function can boost the top ranked solution to be the closest to the x-ray structure. Rapid and accurate calculation of interaction energies between ligand and protein also enables screening of millions of drug candidates/docking poses. Using a unique protocol in which docking by GOLD-PLP, rescoring by ANI-ML potentials and extensive MD simulations along with end state free energy methods are combined, we have screened FDA approved drugs against the SARS-CoV-2 main protease (Mpro). The top six drug molecules suggested by the consensus of these free energy methods have already been in clinical trials or proposed as potential drug molecules in previous theoretical and experimental studies, approving the validity and the power of accuracy in our screening method.

Cucurbit[7]uril-mediated matrix solid phase dispersion extraction strategy combined capillary electrophoresis for detection of biogenic amines in foods

Biogenic amines (BAs) are the vital indicators of food freshness, and monitoring the change of BAs content is quite essential for food safety. Herein, we developed a matrix solid phase dispersion (MSPD) extraction technology based on cucurbit[7]uril (Q[7]) to extract BAs from pork and shrimp. Then, the extracted BAs were analyzed by capillary electrophoresis (CE) with low sample consumption and high analytical efficiency. The factors affecting MSPD extraction were optimized by Plackett-Burman and the Box-Behnken design (BBD). The limits of detection (LODs) were ranging from 0.003 to 0.019 mg kg−1, the recoveries of spiked samples were 80.15 %–110.3 %. The satisfactory accuracy and precision were attributed to the host–guest interaction between Q[7] and BAs. Furthermore, the freshness of pork and shrimp was evaluated by simultaneous determination of four BAs. For its wide linear range, high sensitivity, and cost-effectiveness, the proposed Q[7] mediated MSPD-CE-UV provides meaningful potential prospects in the rapid monitor of food freshness and safety.

Supramolecular Interaction Modulation in Thermosensitive Composites: Enantiomeric Recognition and Chiral Site Regeneration.

Herein, a novel strategy was implemented to modulate the supramolecular interaction between enantiomers and chiral recognition sites (CRSs), effectively resolving the issue of CRS saturation. Randomly methylated-β-cyclodextrin (Rm-β-CD) was used as the CRS (host molecule), and polymerized ionic liquids [poly([vbim]TFSI)] were used as the supramolecular modulator (guest molecule), which self-assembled to generate thermosensitive supramolecular host/guest complexes. The enantiomeric binding capacity and enantioselectivity of chiral separation systems centered on supramolecular host-guest complexes are characterized by a high degree of temperature dependence. Poly([vbim]TFSI) bonded to Rm-β-CD at temperatures between 17 °C ± 3 and 50 °C ± 3 °C, and the binding free energy difference (|ΔΔG|) between the (S)- and (R)-enantiomer was 0.55. Conversely, poly([vbim]TFSI detached from Rm-β-CD at temperatures >50 °C ± 3 °C or <17 °C ± 3 °C, and |ΔΔG| between (S)- and (R)-enantiomer was 0.03. The |ΔΔG| value of the (R)-enantiomer can reach 0.86 in two temperature intervals. Therefore, the binding of poly([vbim]TFSI) to Rm-β-CD afforded the favorable separation of four racemic sample mixtures: mandelic acid (e.e.% = 61.3%), ibuprofen (e.e.% = 21.6%), warfarin (e.e.% = 14.9%), and naproxen (e.e% = 18.2%). The detachment of poly([vbim]TFSI) from Rm-β-CD released the enantiomer bound to CRSs. The decomplexation of mandelic acid reached 75.1%.

A Scalable Robust Microporous Al-MOF for Post-Combustion Carbon Capture.

Herein, a robust microporous aluminum tetracarboxylate framework, MIL-120(Al)-AP, (MIL, AP: Institute Lavoisier and Ambient Pressure synthesis, respectively) is reported, which exhibits high CO2 uptake (1.9mmol g-1 at 0.1bar, 298 K). In situ Synchrotron X-ray diffraction measurements together with Monte Carlo simulations reveal that this structure offers a favorable CO2 capture configuration with the pores being decorated with a high density of µ2-OH groups and accessible aromatic rings. Meanwhile, based on calculations and experimental evidence, moderate host-guest interactions Qst (CO2) value of MIL-120(Al)-AP (-40kJ mol-1) is deduced, suggesting a relatively low energy penalty for full regeneration. Moreover, an environmentally friendly ambient pressure green route, relying on inexpensive raw materials, is developed to prepare MIL-120(Al)-AP at the kilogram scale with a high yield while the Metal- Organic Framework (MOF)is further shaped with inorganic binders as millimeter-sized mechanically stable beads. First evidences of its efficient CO2/N2 separation ability are validated by breakthrough experiments while operando IR experiments indicate a kinetically favorable CO2 adsorption over water. Finally, a techno-economic analysis gives an estimated production cost of ≈ 13 $ kg-1, significantly lower than for other benchmark MOFs. These advancements make MIL-120(Al)-AP an excellent candidate as an adsorbent for industrial-scale CO2 capture processes.

Tunable Fluorescence, Morphology, and Antibacterial Behaviors of Conjugated Oligomers via Host-Guest Supramolecular Self-Assembly.

Host-guest supramolecular self-assembly has become one facile but efficient way to regulate the optical properties of conjugated oligomers and construct promising photofunctional materials. Herein, we design two linear conjugated oligomers terminated with two or four pyridinium moieties, which show different 1:1 'head-to-tail' binding patterns with cucurbit[8]uril (CB[8]) to form host-guest supramolecules. After being encapsulated in the hydrophobic cavity of the CB[8] host, the fluorescence emission of the conjugated oligomers undergoes significant changes, resulting in tunable fluorescence color with enhanced quantum yields. Triggered by the aggregation of supramolecules, the regular or rigid binding modes lead to the formation of cuboids and spheroids in nanoscale, respectively. Due to the macrocyclic-confinement effect, the light-driven reactive oxygen species (ROS) production of the host-guest complex is increased significantly, thereby improving the photodynamic antibacterial performance toward Staphylococcus aureus (S. aureus).

Development of Anti-TNT@Cu-BTC MOF thin film using drop caste method for trinitrotoluene (TNT) sensing

Antibody functionalised Cu-BTC MOF thin film was prepared using drop-casting method on indium tin oxide (ITO) coated glass substrate for trinitrotoluene (TNT) sensing under certain experimental conditions. Initially, APTES functionalization on ITO substrate using EDC-NHS chemistry was carried out, after which biofunctionalization of Anti-TNT on Cu-BTC MOF (1,3,5-tricarboxylic acid as an organic linker and copper ions as metal) thin film was carried out. Each step of sensor fabrication was characterised by the X-ray diffraction, microscopic and spectroscopic techniques. The interaction of one layer with another is confirmed with the help of FTIR and EDX. ITO substrate modification increases resistance at each stage from 1.29 to 3.3 KΩ. This modified substrate used as a working electrode during the sensing experiment. Afterward, response cum detection of 2,4,6-trinitrotoluene (TNT) in the 0.1 ppm to 0.6 ppm range has been noted by impedance method using three electrode systems of an electrochemical workstation. Host-guest interaction cum mechanism between TNT antibody functionalised APTES@Cu-BTC and TNT analyte has been observed which origins change in their resistance/impedance. The variation in resistance is directly proportional to the concentrations, exhibiting a strong linear relationship with 0.9702 value for R2. We find out that the presence of TNT antibody increases the specificity of TNT sensing and minimizes cross-reactivity with unknown/other interfering compounds. The concentration–response graph shows a 0.04 ppm limit of detection at room temperature.

Selective sorting of hexane isomers by anion-functionalized metal-organic frameworks with optimal energy regulation

Extensive efforts have been made to improve the separation selectivity of hydrocarbon isomers with nearly distinguishable boiling points; however, how to balance the high regeneration energy consumption remains a daunting challenge. Here we describe the efficient separation of hexane isomers by constructing and exploiting the rotational freedom of organic linkers and inorganic SnF62− anions within adaptive frameworks, and reveal the nature of flexible host-guest interactions to maximize the gas-framework interactions while achieving potential energy storage. This approach enables the discrimination of hexane isomers according to the degree of branching along with high capacity and record mono-/di-branched selectivity (6.97), di-branched isomers selectivity (22.16), and upgrades the gasoline to a maximum RON (Research Octane Number) of 105. Benefitting from the energy regulation of the flexible pore space, the material can be easily regenerated only through a simple vacuum treatment for 15 minutes at 25 °C with no temperature fluctuation, saving almost 45% energy compared to the commercialized zeolite 5 A. This approach could potentially revolutionize the whole scenario of alkane isomer separation processes.

Bioactive peptide relieves glucocorticoid-induced osteoporosis by giant macrocyclic encapsulation

Bioactive peptides play a crucial role in the field of regenerative medicine and tissue engineering. However, their application in vivo and clinic is hindered by their poor stability, short half-life, and low retention rate. Herein, we propose a novel strategy for encapsulating bioactive peptides using giant macrocycles. Platelet-derived growth factor (PDGF) bioactive mimicking peptide Nap-FFGVRKKP (P) was selected as the representative of a bioactive peptide. Quaterphen[4]arene (4) exhibited extensive host-guest complexation with P, and the binding constant was (1.16 ± 0.10) × 107 M−1. In vitro cell experiments confirmed that P + 4 could promote the proliferation of BMSCs by 2.27 times. Even with the addition of the inhibitor dexamethasone (Dex), P + 4 was still able to save 76.94% of the cells in the control group. Compared to the Dex group, the bone mass of the mice with osteoporosis in the P + 4 group was significantly increased. The mean trabecular thickness (Tb.Th) increased by 17.03%, and the trabecular bone volume fraction (BV/TV) values increased by 40.55%. This supramolecular bioactive peptide delivery strategy provides a general approach for delivering bioactive peptides and opens up new opportunities for the development of peptide-based drugs.

Photo-responsive doxorubicin delivery: Nanogel systems based on azobenzene and host-guest interactions enhanced by squeezing action

Conventional chemotherapy methods impact both normal and cancerous cells; therefore, it is essential to design drug delivery systems to reduce undesired drug effects. Nano-scaled drug delivery systems have the advantage of high retention time in blood as well as the capability of conventional penetration into tissue barriers. In this study, light-sensitive biocompatible nanogels with a core-shell structure have been synthesized and characterized as drug delivery system loaded with doxorubicin (DOX). These smart nanogels possess a hydrophobic core, coated with hydrophilic starch polymeric chains, which are modified with β-cyclodextrin (βCD). The core-shell formation is based on host-guest interaction between azobenzene rings as photochromic agents and βCD hydrophobic cavities. The mechanism of drug release is based on the cis-trans isomerization of azobenzene molecules upon light irradiation and dissociation of crore-shell entities. Due to this isomerization, shrinkage of hydrophobic core and removal of shell occurred simultaneously, which assist the drug release. In conclusion, a nanoscale carrier was designed with sustainable drug release under light irradiation as an external and non-contact stimulus. The synthesized nanogels were characterized by FT-IR, 1H NMR, SEM, DLS, and TEM. In addition, the MTT assay proposed that the viability of the A-431 cells has plunged in the presence irradiated nanogels, also histological studies were performed to evaluate the efficacy of the prepared nanogels in cancerous tissues.

One-pot synthesis of cerium-organic framework@carbon black composites for simultaneous detection of dopamine, uric acid, and acetaminophen

Accurate identification of dopamine (DA), uric acid (UA), and acetaminophen (APAP) is critical to safeguarding human health. However, their simultaneous detection is still challenging due to their similar oxidation potentials. In this work, a series of new composites based on cerium-organic framework (Ce-MOF) and carbon black (CB) were constructed by one-pot method at room temperature. The introduction of CB can significantly affect the conductivity and specific surface area of the composites. The optimal composite Ce-MOF-COOH/CB0.4 can identify DA, UA, and APAP simultaneously with low detection limit of 0.030, 0.045, and 0.057 μM and wide detection range of 2.5–310.0, 3.0–305.0, and 2.5–617.0 μM, respectively. Furthermore, density-functional theory (DFT) calculation was performed to explore the influence of functional groups (-NH2 or –COOH) on the sensing performance. It was found that the introduced functional groups can obviously enhance the host-guest interactions through the formation of strong hydrogen bonds, which is beneficial for promoting sensing performance. In addition, the constructed electrode could also detect DA, UA, and APAP in real samples, which indicated its potential for practical applications. This study provides a feasible approach to utilize MOFs as electrochemical sensors for simultaneously detection of biomolecules.

Para-Phenylenediamine Dimer as a Redox-Active Guest for Supramolecular Systems.

Redox-active components are highly valuable in the construction of molecular devices. We combined two p-phenylenediamines (p-PDA) with a biphenyl (BiPhe) unit to prepare a supramolecular guest 4 consisting of three binding sites for cucurbit[7/8]uril (CBn) and/or cyclodextrins (CD). Supramolecular properties of 4 were investigated using NMR, UV-vis, mass spectrometry and isothermal titration calorimetry. Our analysis revealed that 4 forms higher-order host-guest complexes, wherein a CD unit occupies the central BiPhe site, secured by two CBn units at the terminal p-PDA sites. Additionally, 1 : 1 complexes with α-CD and β-CD, a 1 : 2 complex with γ-CD and 2 : 1 complexes with CB7 and CB8 were identified. Through UV-vis and cyclic voltammetry, redox processes leading to the formation of a stable, deep blue dication diradical of 4 are elucidated. Furthermore, it is demonstrated that CB7 selectively protects oxidised 4 from reduction in the presence of a reducing agent. The supramolecular and redox properties of the structural motif represented by 4 render it an interesting candidate for the construction of supramolecular devices.

ROS-driven supramolecular nanoparticles exhibiting efficient drug delivery for chemo/Chemodynamic combination therapy for Cancer treatment

Drug-based supramolecular self-assembling delivery systems have enhanced the bioavailability of chemotherapeutic drugs and reduced systemic side effects; however, improving the delivery efficiency and responsive release ability of these systems remains challenging. This study focuses primarily on the utilization of per-6-thio-β-cyclodextrin (CD) to link a significant quantity of paclitaxel (PTX) via ROS-sensitive thioketal (TK) linkages (designated as CDTP), thereby allowing efficiently drug release when exposed to high levels of reactive oxygen species (ROS) in the tumor microenvironment. To construct these supramolecular nanoparticles (NPs) with CDTP, we introduced PEGylated ferrocene (Fc) through host-guest interactions. The intracellular hydrogen peroxide (H2O2) is converted into hydroxyl radicals (•OH) through the Fc-catalyzed Fenton reaction. Additionally, the generated Fc+ consumes the antioxidant glutathione (GSH). In both in vivo and in vitro experiments, CDTP@Fc-PEG NPs were absorbed effectively by tumor cells, which increased levels of ROS and decreased levels of GSH, disrupting the redox balance of cancer cells and increasing their sensitivity to chemotherapy. Furthermore, CDTP@Fc-PEG NPs exhibited high tumor accumulation and cytotoxicity without causing significant toxicity to healthy organs. Collectively, our results suggest CDTP@Fc-PEG NPs as a promising supramolecular nano-delivery platform for high drug-loading of PTX and synergistic chemotherapy.

COVID-19 and short-term housing: economic and social impacts and implications

AbstractThe rapid spread of the new coronavirus (COVID-19) around the world since early 2020 has caused significant economic, social, psychological, and public health costs. The COVID-19 pandemic hit almost all economic sectors including the hospitality and tourism industry. This review paper examined the impacts of COVID-19 on short-term housing and the factors influencing these impacts. The existing literature reported generally negative effects of COVID-19 on the operating performance of the short-term accommodation industry. COVID-19 impacted on travellers’ perceptions, host-guest interactions and psychological well-being when choosing short-term accommodation. This review also provides implications for minimising the impacts of COVID-19 or similar future disruptive events on short-term accommodation operations and surviving the crisis in the short-term accommodation sector.

Organic room-temperature phosphorescence of imidazole-based films by self-assembly enhancement strategies

Organic room-temperature phosphorescence (RTP) shows high potential in optical fields, and self-assembly method via various non-covalent interactions is one facile and efficient way to enhance RTP performance. Herein, we investigated the RTP behaviors of three imidazole-based polymer films containing imidazole, methyl imidazolium, and benzyl imidazolium moieties, respectively. Their RTP behaviors and chemical structures were compared and discussed to explore the underlying structure-properties relationships. Owing to plenty of hydrogen bonds of polyacrylamide matrix to lock phosphors, imidazolium-based films gave an obvious green RTP due to cations and iodine anions-enhanced intersystem crossing. The blue RTP signals of imidazole-containing film was aroused by coordination with Zn2+ ions due to crosslinking and heavy atom effects. Moreover, the RTP performance of benzyl imidazolium-based film was remarkably improved by host-guest complexation with cucurbit[7]uril, showing a long lifetime up to 230.6 ms. By utilizing the difference in their RTP lifetimes, information encryption application was successfully achieved as a proof of concept.

Ion Mobility Mass Spectrometry for Large Synthetic Molecules: Expanding the Analytical Toolbox.

Understanding the composition, structure and stability of larger synthetic molecules is crucial for their design, yet currently the analytical tools commonly used do not always provide this information. In this perspective, we show how ion mobility mass spectrometry (IM-MS), in combination with tandem mass spectrometry, complementary techniques and computational methods, can be used to structurally characterize synthetic molecules, make and predict new complexes, monitor disassembly processes and determine stability. Using IM-MS, we present an experimental and computational framework for the analysis and design of complex molecular architectures such as (metallo)supramolecular cages, nanoclusters, interlocked molecules, rotaxanes, dendrimers, polymers and host-guest complexes.

Bioinspired host-tailored polymers based on molecular imprinting for cytokine assessment

Molecular imprinting undergone a substantial boost driven by the awareness of molecularly imprinted polymers (MIPs)-ligand recognition skills. In particular, the introduction of natural-based compounds like cyclodextrins into the structural scaffold of synthetic recognition elements attracted great importance as a novel route to design more friendly-environments for protein binding, while promoting higher selectivity features. Herein, carbon electrodes doped with platinum nanoparticles supported on multiwalled carbon nanotubes and functionalized with polyallylamine (MWCNTs-PAH/Pt) were electrochemically modified with an imprinted sensing layer of poly(β-cyclodextrin-pyrrole) (poly(β-CD-Py)) towards interleukin 6 (IL-6) monitoring. The analytical performance of the biosensor was evaluated by using Cyclic Voltammetry and Electrochemical Impedance Spectroscopy techniques. Along the assembly, experimental parameters like nanomaterial deposition, monomer-protein concentrations and template removal solutions were carefully optimized and discussed. Furthermore, the electrodeposited film was characterized in terms of composition, morphology and structure using scanning electron microscopy (SEM) and Raman spectroscopy. Under optimal conditions, the developed sensor was able to rebind IL-6 over a wide linear range [1 pg/mL – 100 ng/mL], displaying high sensitivity, quick electrochemical response, and specific binding of the target molecule. Overall, this work reported the relevance of using host-guest complexes directly embedded in polymeric chains to generate newly controlled electrochemical sensors holding great potential for protein biosensing.

Determination of pesticide residue in soil samples by molecularly imprinted solid-phase extraction method

Abstract Porous molecularly imprinted polymer (MIP) microspheres were synthesized via iniferter-suspension polymerization method, employing lenacil (LA) as the template molecule and methacrylic acid (MAA) as the functional monomer. The host–guest complexes formed using LA and MAA were characterized by hydrogen nuclear magnetic resonance and ultraviolet–visible absorption spectroscopy. The obtained results showed that the interaction between LA and MAA mainly relied on hydrogen bonding. The surface morphologies and chemical structures of the MIPs were characterized by scanning electron microscopy. MIPs were spherical in shape with a relatively regular sphericity, rough surface structure, and numerous small holes, which significantly reduced the mass transfer resistance of the template molecules and exhibited excellent recognition performance for template molecules. In addition, soil samples were pretreated with solid-phase extraction columns molecularly imprinted with LA, and analyzed by high-performance liquid chromatography. The recoveries of LA, bromacil, and terbacil were up to 89.65%, 53.17%, and 44.63%, respectively. The developed method showed a minimum detection limit of 10–50 µg·mL−1. In view of the continuous increase of public requirements for pesticide residue detection, a versatile pretreatment method was developed that is green, rapid, simple, and can be miniaturized.