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Inspired by nature, artificial hydrogen bond‐based anion receptors have been developed to achieve high anion selectivity; however, their binding affinity is usually low. The potency of these receptors is usually increased by the introduction of aryl substituents, which withdraw electrons from their binding site through the resonance effect. Here, we show that the polarization of the C(sp3)‐H binding site of bambusuril receptors, and thus their potency to bind anions, can be modulated by the inductive effect. The presence of electron‐withdrawing groups on benzyl substituents of bambusurils significantly increases their binding affinities to halides, resulting in the strongest iodide receptor reported to date with an association constant greater than 1013 M−1 in acetonitrile. A Hammett plot showed that while the bambusuril affinity toward halides linearly increases with the electron‐withdrawing power of their substituents, their binding selectivity remains essentially unchanged. [ABSTRACT FROM AUTHOR]

We demonstrate a new method to control the diffusion of guest molecules within cellulose nanocrystal (CNC) matrices containing embedded receptors. Specifically, we modified the structural composition of the guests by connecting them to polymer chains or nanoparticles, to slow down their diffusion rate, leading to controlled and colorful host–guest self-assembly processes within CNC-based materials. Moreover, considering the differences in guest binding affinity, we successfully built a supramolecular system that can exhibit macroscopic color changes by a sequenced exchange process. This system has been implemented in a spontaneous color-evolving film. We anticipate that these materials may be valuable to design a set of self-responsive materials and size exclusion gels functioning as, for example, time-evolving coatings, sustained-releasing materials, and separation columns. [ABSTRACT FROM AUTHOR]

Proteins play a crucial role in determining disease states in humans, making them prime targets for the development of diagnostic sensors. The developed sensor array is used to investigate global proteomic changes by fingerprinting multifactorial disease states in model urine simulating phenylketonuria and in serum from preeclamptic pregnant women. Here, we report a fluorescence-based chemical sensing array that exploits the host-guest interaction between cucurbit[7]uril (CB[7]) and fluorescent triphenylamine derivatives (TPA) to detect a range of proteins. Using linear discriminant analysis, we identify fluorescence fingerprints of 14 proteins with over 98% accuracy in buffer and human serum. The array is optimized on an automated droplet microfluidic-based platform, for high-throughput sensing with controlled composition and lower sample volumes. This sensor enables the discrimination of proteins in physiological buffer and human serum, with promising applications in disease diagnosis.

Atomically precise Pd-thiolate clusters are well-known for their well-defined structures and diverse applications involving catalysis, sensors, and biomedicine. While many of these clusters have been studied, their molecular structures typically feature a tiara-like arrangement. In this study, we present the first example of a non-tiara-like Pd-thiolate cluster: the octahedral Pd 6 (SC 6 H 11 ) 12 (denoted as Pd 6 -Oct). The composition and geometric structure of the cluster were characterized using electrospray ionization mass spectrometry (ESI-MS) together with single-crystal X-ray diffraction (SXRD). Despite having a similar chemical composition to tiara-like Pd 6 (SC 2 H 4 Ph) 12 (denoted as Pd 6 -Tia), Pd 6 -Oct exhibits a distinctly different geometric structure. Additionally, UV-vis-NIR absorption spectroscopy combined with quantum chemical calculations provided valuable insights into the electronic structures of these clusters. The excited-state dynamics, host-guest chemistry, and the catalytic properties of Pd 6 -Oct and Pd 6 -Tia were examined to compare their structure-property relationships. This research represents significant advances in the synthesis and understanding of structure-property correlations in Pd-thiolate clusters.

The fabrication of a membrane with the capability of chiral selective transport is a big challenge in the membrane separation of chiral drugs. To solve the problem of chiral selectivity in membrane separation, drug/metabolite transport (DMT) in the cell membrane inspires a bionic strategy based on the nanochannel membrane. Herein, the DMT-inspired nanochannel membrane is fabricated by the self-assembly of cyclodextrin (CD) in nanochannels and used for the chiral transport and separation of model chiral drugs such as naproxen (NAP). As a result, the β-CD-self-assembled nanochannel membrane shows chiral transport of (S)-naproxen (S-NAP) and achieves the chiral separation of racemic drugs. Moreover, a mechanism of chiral separation is proposed that the chiral selective interaction increases the surface charge density, causing chiral enrichment and transport. Given these promising results, the study of the β-CD-self-assembled nanochannel membrane suggests a bionic strategy for the separation of chiral drugs. [ABSTRACT FROM AUTHOR]

Zirconium metal-organic frameworks (Zr-MOFs) are potential candidates for decontamination of water resources from harmful pollutants due to their modulable porosity and chemical stability in aqueous solutions. Linker functionalization is an approach for tuning the host-guest chemistry of Zr-MOFs and extends their applications in environmental monitoring. In this work, the structure of UiO-66(Zr) (formulated Zr 6 (OH) 4 O 4 (BDC) 6 , BDC 2- = benzene-1,4-dicarboxylate) was functionalized with dihydrotetrazine group via postsynthesis linker exchange (PSLE) method. The functionalized framework, UiO-66(Zr)-DHTZ, was applied for the removal of arsenate ions from aqueous solutions. The results show that UiO-66(Zr)-DHTZ can adsorb 583 mg g -1 of As(V) at pH = 7 after 2 h, which is significantly higher than that of the UiO-66(Zr). According to X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR), the removal mechanism is based on possible hydrogen bindings between free -C-NH and -C═N- sites of dihydrotetrazine function with -O - and -OH sites of As(V) species. Removal tests in real samples show that UiO-66(Zr)-DHTZ still has a high capacity (220 mg g -1 ) to As(V) ions in complex matrixes and also can decrease the concentration of As(V) below the detection limit (0.05 ppm) of the inductively coupled plasma optical emission spectroscopy (ICP-OES) method. Since the dihydrotetrazine-decorated UiO-66(Zr)-DHTZ reaches one the highest adsorption capacities to As(V) species, it can be considered a potential candidate for water treatment in real-life applications.

Rechargeable aqueous zinc-ion batteries are practically plagued by the short lifespan and low Coulombic efficiency (CE) of Zn anodes resulting from random dendrite deposition and parasitic reactions. Herein, the host-guest chemistry of cucurbituril additive with Zn 2+ to achieve longstanding Zn anodes is manipulated. The macrocyclic molecule of cucurbit[5]uril (CB[5]) is delicately designed to reconstruct both the CB[5]-adsorbed electric-double layer (EDL) structure at the Zn interface and the hydrated sheath of Zn 2+ ions. Especially benefiting from the desirable carbonyl rims and suitable hydrophobic cavities, the CB[5] has a strong host-guest interaction with Zn 2+ ions, which exclusively permits rapid Zn 2+ flux across the EDL interface but retards the H 2 O radicals and SO 4 2- . Accordingly, such a unique particle redistributor warrants long-lasting dendrite-free deposition by homogenizing Zn nucleation/growth and significantly improved CE by inhibiting side reactions. The Zn anode can deliver superior reversibility in CB[5]-containing electrolyte with a ninefold increase of cycle lifetime and an elevated CE of 99.7% under harsh test conditions (10 mA cm -2 /10 mA h cm -2 ). The work opens a new avenue from the perspective of host-guest chemistry to propel the development of rechargeable Zn metal batteries and beyond., (© 2023 Wiley‐VCH GmbH.)

Highlights • A new supramolecular polymer was fabricated by crown ether-based host‒guest interaction and Ag-coordination. • The supramolecular polymer displayed sensitive property to H 2 S. • The supramolecular polymer was made into a thin film and used as a convenient test kit for detecting H 2 S. • The thin film was more stable under moisture and sunlight than simple silver ion. Abstract A supramolecular polymer was fabricated via crown ether-based host–guest interaction and Ag-coordination. It displayed hydrogen sulfide sensitive property. In addition, the supramolecular polymer was made into a thin film which can be used to detect hydrogen sulfide. [ABSTRACT FROM AUTHOR]

• Curcubit[8]uril and 1,2-bis(4-pyridyl)ethylene form a 1:2 inclusion complex. • The crystal structure of [(C 48 H 48 N 32 O 16)@2(C 12 H 12 N 2)4(Cl)] is reported. • The host-guest complex is weakly fluorescent. • Addition of the insecticide pymetrozine greatly enhanced the fluorescence. • The system is capable of detecting pymetrozine. Herein, we report a simple fluorescence-enhanced system for the selective recognition and determination of the insecticide pymetrozine. 1H NMR spectroscopic data indicate that 1,2-bis(4-pyridyl)ethylene (BPE) is partially encapsulated in the cavity of the cucurbit[8]uril (Q[8]) in aqueous solution, forming a stable 1:2 host-guest inclusion complex. Good evidence is also provided by other characterization techniques including single crystal X-ray diffraction, UV–Vis and fluorescence spectroscopies. This host-guest inclusion complex shows weak fluorescence in aqueous solution. Interestingly, the addition of pymetrozine greatly enhanced the fluorescence of the host-guest inclusion complex. In contrast, no significant fluorescence enhancement was observed on addition of 10 other pesticides. The concentration of pymetrozine in aqueous solution was easily detected based on the linear relationship between fluorescence intensity and pymetrozine concentration. Therefore, this paper reports a new method to identify and determine pymetrozine by fluorescence enhancement. T his paper demonstrated a simple and validated fluorescence enhancing method for the selective recognition and determination of the pymetrozine. 1,2-bis(4-pyridyl)ethylene (BPE) can be encapsulated into the cucurbit[8]uril (Q[8]) in aqueous solution to form stable 1:2 host−guest inclusion complex. Interestingly, the addition of the pymetrozine dramatically enhanced the fluorescence intensity of the inclusion complex. In contrast, the addition other pesticides gives no fluorescence variation. Accordingly, a new fluorescence enhancing method for the recognition and determination of the pymetrozine was established. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel host−guest recognition motif based on a water-soluble pillar[7]arene ( WP7) and a 2,7-diazapyrenium salt ( DMDAP) was prepared. According to the integrated results of 1H NMR, 2D NOESY, UV-vis spectroscopy and fluorescence titration experiments, we demonstrated that the molecular recognition of WP7 to DMDAP in water not only has high association constant but also has pH-responsiveness. Subsequently, we took advantage of this molecular recognition motif to fabricate a supra-amphiphile based on WP7 and an amphiphilic 2,7-diazapyrenium derivative DAPAC. Its controllable self-assembly in water was also investigated by means of TEM and DLS techniques. [ABSTRACT FROM AUTHOR]

Non-covalent self-assembly of multi-components is a promising strategy for constructing supramolecular hydrogels. However, it remains challenging to achieve the multi-responsiveness to external stimuli for supramolecular hydrogels through a low-molecular-weight hydrogelator. Herein, we report a host−guest complex as low-molecular-weight hydrogelator for constructing graphene oxide (GO)-based supramolecular hybrid hydrogels. A 1:2 homoternary complex (CB[8]· NMAH + 2) was formed through host−guest encapsulation of two protonated naphthalen-2-ylmethanamine (NMAH +) molecules in cucurbit[8]uril (CB[8]) host and worked as dynamically assembled electrostatic cross-linker in the presence of GO. The resulted GO hydrogels showed shear-thinning, self-healing properties, and were stimuli-responsive to pH and competing guests. The proposed concept of "assembled electrostatic cross-linker" (AEC) would be extended to construct other novel stimuli-responsive supramolecular materials. [Display omitted] • A facile gelation strategy was proposed by designing a low-molecular-weight host−guest hydrogelator. • The host−guest complex worked as a dynamically reversible cross-linker to yield GO -based hydrogels. • The strategy is expected to open a new route for designing and constructing novel multifunctional supramolecular materials. [ABSTRACT FROM AUTHOR]

Anticoagulant surface modification of blood-contacting materials has been shown to be effective in preventing thrombosis and reducing the dose of anticoagulant drugs that patients take. However, commercially available anticoagulant coatings, that is, both bioinert and bioactive coatings, are typically based on a single anticoagulation strategy. This puts the anticoagulation function of the coating at risk of failure during long-term use. Considering the several pathways of the human coagulation system, the synergy of multiple anticoagulation theories may provide separate, targeted effects at different stages of thrombosis. Based on this presumption, in this work, negatively charged poly(sodium p -styrenesulfonate- co -oligo(ethylene glycol) methyl ether methacrylate) and positively charged poly(lysine- co -1-adamantan-1-ylmethyl methacrylate) were synthesized to construct matrix layers on the substrate by electrostatic layer-by-layer self-assembly (LBL). Amino-functionalized β-cyclodextrin (β-CD-PEI) was subsequently immobilized on the surface by host-guest interactions, and heparin was grafted. By adjusting the content of poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA), the interactions between modified surfaces and plasma proteins/cells were regulated. This multistage anticoagulant surface exhibits inertness at the initial stage of implantation, resisting nonspecific protein adsorption (POEGMA). When coagulation reactions occur, heparin exerts its active anticoagulant function in a timely manner, blocking the pathway of thrombosis. If thrombus formation is inevitable, lysine can play a fibrinolytic role in dissolving fibrin clots. Finally, during implantation, endothelial cells continue to adhere and proliferate on the surface, forming an endothelial layer, which meets the blood compatibility requirements. This method provides a new approach to construct a multistage anticoagulant surface for blood-contacting materials.

Identifying nitroreductase (NTR) with fluorescent techniques has become a research hotspot, due to its good sensitivity and selectivity toward the early-stage cancer diagnosis and monitoring. Herein, a host-guest reporter ( NAQA ⊂ Zn-MPPB ) is successfully achieved by encapsulating the NTR probe NAQA into a new NADH-functioned metal-organic cage Zn-MPPB , which makes the reporter for ultrafast detection of NTR within dozens of seconds in solution. The host-guest strategy fuses the Zn-MPPB and NAQA to form a pseudomolecule material, which changes the reaction process of NTR and NAQA from a double substrates mechanism to a single substrate one, and accelerates the reduction efficiency of NAQA . This advantage make the new host-guest reporter exhibit a linear relationship between emission changes and NTR concentration, and it shows better sensitively toward NTR than that of NAQA . Additionally, the positively charged water-soluble metal-organic cage can encapsulate NAQA in the cavity, promote it to dissolve in an aqueous environment, and facilitate their accumulation into tumor cells. As expected, such host-guest reporter displays a fast and high efficiently imaging capability toward NTR in tumor cells and tumor-bearing mice, and flow cytometry assay is conducted to corroborate the capability as well, implying the considerably potential of host-guest strategy for early tumor diagnosis and treatment.

S -Nitrosoglutathione (GSNO) is a nontoxic nitric oxide (NO)-donating compound that occurs naturally in the human body. The use of GSNO to deliver exogenous NO for therapeutic and protective applications is limited by the high lability of dissolved GSNO in aqueous formulations. In this paper, we report a host-guest chemistry-based strategy to modulate the GSNO reactivity and NO release kinetics for the design of anti-infective catheters and hydrogels. Cyclodextrins (CDs) are host molecules that are typically used to encapsulate hydrophobic guest molecules into their hydrophobic cavities. However, we found that CDs form inclusion complexes with GSNO, an extremely hydrophilic molecule with a solubility of over 1 M at physiological pH. More interestingly, the host-guest complexation reduces the decomposition reactivity of GSNO in the order of αCD > γCD > hydroxypropyl βCD. The lifetime of 0.1 M GSNO is increased to up to 15 days in the presence of CDs at 37 °C, which is more than twice the lifetime of free GSNO. Quantum chemistry calculations indicate that GSNO in αCD undergoes a conformational change that significantly reduces the S-NO bond distance and increases its stability. The calculated S-NO bond dissociation enthalpies of free and complexed GSNO well agree with the experimentally observed GSNO decomposition kinetics. The NO release from GSNO-CD solutions, compared to GSNO solutions, has suppressed initial bursts and extended durations, enhancing the safety and efficacy of NO-based therapies and device protections. In an example application as an anti-infective lock solution for intravascular catheters, the GSNO-αCD solution exhibits potent antibacterial activities for both planktonic and biofilm bacteria, both intraluminal and extraluminal environments, both prevention and treatment of infections, and against multiple bacterial strains, including a multidrug-resistant strain. In addition to solutions, the inclusion complexation also enables the preparation of GSNO hydrogels with enhanced stability and improved antibacterial efficacy. Since methods to suppress and control the GSNO decomposition rate are rare, this supramolecular strategy provides new opportunities for the formulation and application of this natural NO donor.

• Separation ability of the three COFs-coated CEC were evaluated by separating 8 phthalates. • Relationship between CEC separation ability of three COFs and their structures were investigated. • Docking and DFT were proceeded to get insight into the host−guest interactions. • Reason for the different separation ability was explored on molecular level. Covalent organic frameworks (COFs) have great potential applications in chromatographic separation. So it is crucial to understand the relationship between the separation ability of COFs and their structures. Here we report a strategy to evaluate the separation ability of three 2D COFs and explore the relationship between separation ability and their molecular structures. The three 2D COFs (COF-LZU1, COF-42 and COF-LZU8) have one same building unit 1,3,5-triformylbenzene, while varied from the conjugated linking units and functional side-chains. They were used to construct coated capillary column for capillary electrochromatographic separation of same groups of phthalates. They exhibited different separation efficiencies. COF-42 and COF-LZU8 coated capillary columns provided good signal resolutions and high column efficiencies with high theoretical plate numbers. It is demonstrated that COFs with hydrazone unit and longer side-chains provided higher selectivity and resolutions for the phthalates separation. Molecular simulations and DFT calculations were further proceeded to explore the deep reason why the three COFs coated CEC displayed different separation ability based on the host−guest interactions on molecular level. This work highlights a new opportunity to select or design functional COFs and improve their efficiency in chromatographic separation based on host−guest chemistry. [ABSTRACT FROM AUTHOR]

Curcumin has a limited clinical application because of its extremely poor accessibility. In the present study, improved curcumin bioavailability within a castor oil polyurethane/layered double hydroxide (LDH) wound cover was achieved by preparing a curcumin p -sulfonic acid calix[4]arene (SC4A) inclusion complex. Then, it was utilized to intercalate MgAl-layered double hydroxide (MgAl-LDH) nanosheets. The incorporation of the nanostructure into a PU/Cur-SC4A-LDH film provided bacteria-killing performance against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. This finding is due to an increase in curcumin bioavailability in the PU matrix. Furthermore, all PU nanocomposites exhibited appropriate cytocompatibility based on an MTT assay. Mainly, the proliferation of L929 fibroblast cells in contact with the PU/Cur-SC4A-LDH sample was significantly further enhanced than that for other nanocomposites within 7 days. This observation can be related to the better availability of curcumin on the film's surface, which causes an improvement in the proliferation rate of cells. Regarding the histological results, the hematoxylin and eosin (H&E) images showed faster epidermal layer formation and a larger quantity of matured hair follicles for PU/Cur-SC4A-LDH-healed wounds in comparison with those for the negative control over a period of 28 days. Thus, this practical healing ability of the PU/Cur-SC4A-LDH nanocomposite makes it a promising candidate as a wound dressing film.

We describe the preparation of oil-in-water (o/w) colloidal particles with a polypyrrole (pPy) shell in which cyclodextrin has been incorporated at the oil-water interface via either physical adsorption or reaction with the pPy shell. The utility of these particles was assessed by the extraction of organic dyes from water. In all cases, we found that cyclodextrin incorporation significantly improved dye uptake, giving up to 78 ± 11% dye extraction in the case of a 100 ppm solution of 4-nitroaniline with a covalently incorporated cyclodextrin. We demonstrated the ability of our colloidal particles to extract nicotine-derived nitrosamine ketone (NNK), a potent carcinogen, from aqueous solution. By treating the solution containing 100 ppm NNK with our particles over 24 and 48 h, we found that NNK removal reached 65 ± 2 and 83 ± 1%, respectively. The uptake could be improved by re-treating a solution with additional freshly prepared particles, to achieve 95 ± 1% NNK extraction with a covalently incorporated cyclodextrin.

Organophosphate nerve agents and pesticides are extremely toxic compounds because they result in acetylcholinesterase (AChE) inhibition and concomitant nerve system damage. Herein, we report the synthesis, structural characterization, and proof-of-concept utility of zirconium metal-organic polyhedra (Zr-MOPs) for organophosphate poisoning treatment. The results show the formation of robust tetrahedral cages [(( n -butylCpZr) 3 (OH) 3 O) 4 L 6 ]Cl 6 ( Zr-MOP-1 ; L = benzene-1,4-dicarboxylate, n -butylCp = n -butylcyclopentadienyl, Zr-MOP-10 , and L = 4,4'-biphenyldicarboxylate) decorated with lipophilic alkyl residues and possessing accessible cavities of ∼9.8 and ∼10.7 Å inner diameters, respectively. These systems are able to both capture the organophosphate model compound diisopropylfluorophosphate (DIFP) and host and release the AChE reactivator drug pralidoxime (2-PAM). The resulting 2-PAM@Zr-MOP-1(0) host-guest assemblies feature a sustained delivery of 2-PAM under simulated biological conditions, with a concomitant reactivation of DIFP-inhibited AChE. Finally, 2-PAM@Zr-MOP systems have been incorporated into biocompatible phosphatidylcholine liposomes with the resulting assemblies being non-neurotoxic, as proven using neuroblastoma cell viability assays.

The fundamental implications that chirality has in science and technology require continuous efforts for the development of fast, economic, and reliable quantitative methods for enantiopurity assessment. Among the different analytical approaches, chiroptical techniques in combination with supramolecular methodologies have shown promising results in terms of both costs and time analysis. In this article, a tris(2-pyridylmethyl)amines ( TPMA )-based supramolecular cage is able to amplify the circular dichroism (CD) signal of a series of chiral dicarboxylic acids also in the presence of a complex mixture. This feature has been used to quantify tartaric acid in wines and to discriminate different matrixes using principal component analysis (PCA) of the raw CD data.

Cocaine (Coc) is one of the illegal drugs and is harmful to digestive, immune, cardiovascular and urogenital systems. To achieve drug abuse control and legal action, it is essential to develop an effective method for cocaine analysis. In this work, an aptasensor has been developed using atom transfer radical polymerization (ATRP) based on host−guest chemistry for electrochemical analysis of cocaine. The NH 2 −DNA (Apt1) was immobilized on the indium tin oxide (ITO) electrode via addition reaction, and Fc−DNA (Apt2) was introduced to ITO relying on the specific recognition of cocaine. The Apt2 can initiate host−guest chemistry between Apt2 and ATRP initiators (β−CD−Br 15), then the β−CD−Br 15 further triggers ATRP. Moreover, ATRP avoids the sluggish kinetics and poor coupling capability sustained. The result shows a sensitive and selective analysis of cocaine within a linear range from 0.1 ng/mL to 10 μg/mL (R2 = 0.9985), with the detection limit down to 0.0335 ng/mL. Thus, this strategy provides a universal method for the analysis of illegal drugs. [Display omitted] • Firstly, it was reported for cocaine detection based on host−guest chemistry and atom transfer radical polymerization (ATRP). • Ultra-high efficiency was discovered in the synthesized macroinitiator β−CD−Br 15. • This biosensor was successfully achieved in biological samples. [ABSTRACT FROM AUTHOR]

Size-selective catalysis is of key importance in the conversion of crude oil or biomass. Here, we fabricate three pillar[5]arene-integrated porous organic polymers with three-dimensional (3D) network structures using 3D cross-linkers. The resulting polymers possess a high surface-to-mass ratio and exhibit exceptional size-selective catalysis in Knoevenagel condensation reactions. In addition, a mechanistic study indicates that the size-selective catalysis is due to the host-guest interaction between pillar[5]arene and substrates. This study suggests that macrocycle-containing polymers could be a promising candidate for size-selective catalysis.

Small molecules that are capable of toggling between multiple and definite conformational states under external stimuli have great potential for use in molecular switches or sensors. However, currently developed regulation approaches for these switchable molecules mostly involve covalent bond-breaking/reforming processes, thereby inevitably producing byproducts or causing fatigue accumulation. Herein, we report a simple but successful model whose molecular conformation can be precisely manipulated between stretched and folded forms by employing host-guest interactions with rigid macrocycles, thus avoiding possible side reactions and fatigue accumulation and possessing excellent reversibility. Moreover, the conformation states of this molecule can be visualized and identified by luminous readout, endowing it with real-time self-reporting features. Furthermore, this controllable and reversible conformational conversion is accompanied by various valuable functions, including controllable multicolor emission; ratiometric fluorescent thermosensing with high temperature resolution, excellent reversibility, lock/unlock switching, and especially linear detection range tunability; and in addition real-time intracellular temperature sensing and imaging, disclosing the intriguing microscopic "conformation-function" relationship based on a single molecule.

The regulation of surface wettability and cell adhesion behavior in a mild and unperturbed state at the interface remains a challenging task. To address this task, we adopt a strategy, based on bridging the host-guest recognition capacities of pillar[5]arene and good attachment for cell adhesion abilities of graphene oxide, to construct a smart pillar[5]arene triazole-linked naphthalene-modified graphene oxide interface. The hybrid surface exhibited a good stimuli-responsive selectivity toward arginine, as demonstrated by the wettability and cell adhesion behavior. Further studies at molecular levels indicated that the recognition mechanism of arginine was probably due to the formation of a host-guest complex driven by π-π stacking interactions between the cavity of pillar[5]arenes and arginine, which eventually resulted in the change in surface wettability and cellular adhesion behavior. It not only signifies a host-guest interaction strategy for the design of smart devices via the host-guest effect but also inspires the design of high-performance biointerface for affinity-adherent cells without exposing cells to harsh physical and chemical conditions.

In this work, the selectivity of two well-known cryptands, ([2.2.1]cryptand (221) and [2.2.2]cryptand (222), for sodium and potassium cations in both the gas phase and solution are compared to that of two familiar crown ethers, 18-crown-6 (18C6) and dibenzo-18-crown-6 (DB18C6). Intrinsic cation affinity of hosts, cavity size fitting, deformation/strain of hosts as well as solvent effect, for complexation of hosts with cations were calculated at DFT (BP86 and B97-1) level of theory using def2-TZVP triple zeta basis set. The resulting data show that the larger stability of [M ⊂ 221 + and [M ⊂ 222 + complexes relative to [M ⊂ 18C6 + and [M ⊂ DB18C6 + complexes is due to the larger intrinsic affinity of 222 and 221 hosts for both Na+ and K+ cations. On the other hand, the data show that the size match is in disagreement with larger intrinsic affinity of [Na ⊂ Host + complexes compared to [K ⊂ Host + complexes studied here. The results also show that the intrinsic affinities of all four hosts for Na+ are greater than those for K+, but the hosts 222 , 18C6 and DB18C6 are K+-selective in solution due to the solvent effect. Thus, obviously the main reason for higher selectivity of 222 , 18C6 and DB18C6 hosts for K+ compared to Na+ is the solvent effect and not a greater affinity and/or a better size match. The above conclusions were further confirmed by a good correlation between the experimental and calculated formation constants in solution. Unlabelled Image • The selectivity of well-known cryptands and crown ethers for Na+ and K+ cations are studied. • The size match is in disagreement with larger intrinsic affinity of [Na ⊂ Host + complexes. • The solvent effect is the main reason for higher selectivity of most hosts for potassium. • There is a good correlation between the experimental and calculated logK values in solution. [ABSTRACT FROM AUTHOR]

Circumventing the impact of agrochemicals on aquatic environments has become a necessity for health and ecological reasons. Herein, we report the use of a family of five eco-friendly water-stable isoreticular metal-organic frameworks (MOFs), prepared from amino acids, as adsorbents for the removal of neonicotinoid insecticides (thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid) from water. Among them, the three MOFs containing thioether-based residues show remarkable removal efficiency. In particular, the novel multivariate MOF {Sr II Cu II 6 [( S,S )-methox] 1.5 [( S,S )-Mecysmox] 1.50 (OH) 2 (H 2 O)}·36H 2 O ( 5 ), featuring narrow functional channels decorated with both -CH 2 SCH 3 and -CH 2 CH 2 SCH 3 thioalkyl chains-from l-methionine and l-methylcysteine amino acid-derived ligands, respectively-stands out and exhibits the higher removal efficiency, being capable to capture 100% of acetamiprid and thiacloprid in a single capture step under dynamic solid-phase extraction conditions-less than 30 s. Such unusual combination of outstanding efficiency, high stability in environmental conditions, and low-cost straightforward synthesis in 5 places this material among the most attractive adsorbents reported for the removal of this type of contaminants.

Gas-responsive nanochannels have great relevance for applications in many fields. Inspired by CO 2 -sensitive ion channels, herein we present an approach for designing solid-state nanochannels that allow controlled regulation of ion transport in response to alternate CO 2 /N 2 stimuli. The pillar[5]arene ( P5N ) bearing diethylamine groups can convert into the water-soluble host P5C , containing cationic tertiary ammonium salt groups after absorbing CO 2 . Subsequently, the nanochannel walls are tailored using P5N -based host-guest chemistry. The ion transport rate of K + in the P5N nanochannels under CO 2 was 1.66 × 10 -4 mol h -1 m -2 , whereas that under N 2 was 7.98 × 10 -4 mol h -1 m -2 . Notably, there was no significant change to the ion current after eight cycles, which may indicate the stability and repeatability of CO 2 -activated ion nanochannels. It is speculated that the difference in ion conductance resulted from the change in wettability and surface charge within the nanochannels in response to the gas stimuli. Achieving CO 2 -activated ion transport in solid-state nanochannels opens new avenues for biomimetic nanopore systems and advanced separation processes.

Enhanced emission and adjustable wavelength for single luminogen systems are highly desirable in the scope of photoluminescent materials. Herein, a supramolecular strategy has been proposed for supramolecular assembly-induced enhanced emission and valid emission manipulation by fabricating an amphiphilic copolymer host material with pillar[5]arene units as the side chains, whereby cyanovinylene-based (CV) derivatives are anchored to the polymer hosts via host-guest interactions. The guest-bearing copolymers can further form luminescent supramolecular polymer nanoparticles (SPNs). Remarkably, the as-prepared SPNs exhibit dramatic emission enhancement and tunable fluorescence wavelength, ascribing to the synergetic effects involving the restriction of intramolecular motions and the prevented excimer formation for CV moieties, as endowed by host-guest interactions and the entanglement of the polymer chains. Furthermore, the SPNs can be established as efficient artificial light-harvesting systems via the inclusion of Nile red into the particles for broadened emission spectra. As a proof-of-concept study, the use of pillar[5]arene-containing polymer hosts largely facilitates the emission enhancement and wavelength adjustment for the inherent luminogens, setting the basis for the supramolecular design of highly tunable luminescent systems.

To achieve a rapid asymmetry conversion, the substrate objects suffer from accelerated kinetic velocity and random rotation at the cost of selectivity. Inspired by natural enzymes, optimizing the host-guest configuration will realize the high-performance enantioselective conversion of chemical reactions. Herein, multivariate binding interactions were introduced into the 1D channel of a chiral catalyst to simulate the enzymatic action. An imidazolium group was used to electrophilically activate the C═O unit of a ketone substrate, and the counterion binds the hydrogen donor isopropanol. This binding effect around the catalytic center produces strong stereo-induction, resulting in high conversion (99.5% yield) and enantioselectivity (99.5% ee) for the asymmetric hydrogenation of biomass-derived acetophenone. In addition, the turnover frequency of the resulting catalyst (5160 h -1 TOF) is more than 58 times that of a homogeneous Ru-TsDPEN catalyst (88 h -1 TOF) under the same condition, which corresponds to the best performance reported till date among all existing catalysts for the considered reaction.

When nanoparticles (NPs) are exposed to biological media, proteins are adsorbed, forming a so-called protein corona (PC). This cloud of protein aggregates hampers the targeting and transport capabilities of the NPs, thereby compromising their biomedical applications. Therefore, there is a high interest in the development of technologies that allow control over PC formation, as this would provide a handle to manipulate NPs in biological fluids. We present a strategy that enables the reversible disruption of the PC using external stimuli, thereby allowing a precise regulation of NP cellular uptake. The approach, demonstrated for gold nanoparticles (AuNPs), is based on a biorthogonal, supramolecular host-guest interactions between an anionic dye bound to the AuNP surface and a positively charged macromolecular cage. This supramolecular complex effectively behaves as a zwitterionic NP ligand, which is able not only to prevent PC formation but also to disrupt a previously formed hard corona. With this supramolecular stimulus, the cellular internalization of AuNPs can be enhanced by up to 30-fold in some cases, and even NP cellular uptake in phagocytic cells can be regulated. Additionally, we demonstrate that the conditional cell uptake of purposely designed gold nanorods can be used to selectively enhance photothermal cell death.

Here, we demonstrate a supramolecular latching tool for bio-orthogonal noncovalent anchoring of small synthetic molecules in live animal models using a fully synthetic high-affinity binding pair between cucurbit[7]uril (CB[7]) and adamantylammonium (AdA). This supramolecular latching system is small (∼1 kDa), ensuring efficient uptake into cells, tissues, and whole organisms. It is also chemically robust and resistant to enzymatic degradation and analogous to well-characterized biological systems in terms of noncovalent binding. Occurrence of fluorescence resonance energy transfer (FRET) between cyanine 3-CB[7] (Cy3-CB[7]) and boron-dipyrromethene 630/650X-AdA (BDP630/650-AdA) inside a live worm ( Caenorhabditis elegans ) indicates efficient in situ high-affinity association between AdA and CB[7] inside live animals. In addition, selective visualization of a cancer site of a live mouse upon supramolecular latching of cyanine 5-AdA (Cy5-AdA) on prelocalized CB[7]-conjugating antibody on the cancer site demonstrates the potential of this synthetic system for in vivo cancer imaging. These findings provide a fresh insight into the development of new chemical biology tools and medical therapeutic systems.

Organic thin-film transistors (OTFTs) have attracted intense attention as promising electronic devices owing to their various applications such as rollable active-matrix displays, flexible nonvolatile memories, and radiofrequency identification (RFID) tags. To further broaden the scope of the application of OTFTs, we focus on the host-guest chemistry combined with the electronic devices. Extended-gate types of OTFTs functionalized with artificial receptors were fabricated to achieve chemical sensing of targets in complete aqueous media. Organic and inorganic ions (cations and anions), neutral molecules, and proteins, which are regarded as target analytes in the field of host-guest chemistry, were electrically detected by artificial receptors. Molecular recognition phenomena on the extended-gate electrode were evaluated by several analytical methods such as photoemission yield spectroscopy in the air, contact angle goniometry, and X-ray photoelectron spectroscopy. Interestingly, the electrical responses of the OTFTs were highly sensitive to the chemical structures of the guests. Thus, the OTFTs will facilitate the selective sensing of target analytes and the understanding of chemical conversions in biological and environmental systems. Furthermore, such cross-reactive responses observed in our studies will provide some important insights into next-generation sensing systems such as OTFT arrays. We strongly believe that our approach will enable the development of new intriguing sensor platforms in the field of host-guest chemistry, analytical chemistry, and organic electronics.

The polymerization of acrylamide, dopamine methacrylamide, and bis-acrylamide in the presence of one of the electron acceptors, N , N '-dimethyl-4,4'-bipyridinium, ( 1 ), N , N '-dimethylbipyridinium-4,4'-ethylene, ( 2 ), or bipyridinium dithienylethene, ( 3 ), yields hydrogel matrices of high stiffness that are cooperatively cross-linked by bis-acrylamide and electron donor (dopamine)-acceptor complexes. Washing off the diffusional electron acceptor units yields molecularly imprinted matrices of lower stiffness, stabilized only by the bis-acrylamide bridges that include specific binding sites for the selective association of the electron acceptor ( 1 ), ( 2 ), or ( 3 ). These imprinted hydrogel matrices show selective recovery of the stiff properties upon binding the respective electron acceptor units to the imprinted sites. The control over the stiffness properties enables the development of shape-memory, molecularly imprinted hydrogels and stiffness-based sensors. The results show how molecularly imprinted sites translate into macroscopic shape-memory properties of hydrogels.

Colloidal stability is among the key challenges the pharmaceutical industry faces during the production and manufacturing of protein therapeutics. Self-association and aggregation processes can not only impair therapeutic efficacy but also induce immunogenic responses in patients. Aggregation-prone regions (APRs) consisting of hydrophobic patches are commonly identified as the source for colloidal instability, and rational strategies to mitigate aggregation propensity often require genetic engineering to eliminate hydrophobic amino acid residues. Here, we investigate cucurbit[7]uril (CB[7]), a water-soluble macrocycle able to form host-guest complexes with aromatic amino acid residues, as a potential excipient to mitigate protein aggregation propensity. Two monoclonal antibodies (mAbs), one harboring an APR and one lacking an APR, were first assessed for their colloidal stability (measured as the translational diffusion coefficient) in the presence and absence of CB[7] using dynamic light scattering. Due to the presence of a tryptophan residue within the APR, we were able to monitor changes in intrinsic fluorescence in response to increasing concentrations of CB[7]. Isothermal titration calorimetry and NMR spectroscopy were then used to characterize the putative host-guest interaction. Our results suggest a stabilizing effect of CB[7] on the aggregation-prone mAb, due to the specific interaction of CB[7] with aromatic amino acid residues located within the APR. This provides a starting point for exploring CB[7] as a candidate excipient for the formulation of aggregation-prone mAbs.

With a simple design, different core-shell-structured cyclodextrin metal-organic frameworks (CD-MOFs) can realize delayed release and bimodal release of a monocomponent and ordered release of a bicomponent, which establishes the basis for a future complicated programming cargo release system.

Creatinine is a metabolite present in urine, and its concentration is used to diagnose and monitor kidney performance. For that reason, the development of new sensors to analyze this metabolite and obtain accurate results in a short period of time is necessary. An optical disposable sensor for monitoring creatinine levels in urine is described. The system, based on a new aryl-substituted calix[4]pyrrole synthetic receptor, has an unusual coextraction scheme. Due to the low p K a values of creatininium (p K a 4.8), a careful selection of a lipophilic pH indicator that works in acid medium is required. The sensor components were optimized, and the new sensor displays a good response time to creatinine (approximately 3 min) over a wide dynamic range (from 1 × 10 -5 to 1 × 10 -2 M). Moreover, the optical selectivity coefficients obtained for creatinine over common cations present in urine meet the requirements for real sample measurements. With a good sensor-to-sensor reproducibility (RSD, 5.1-6.9% in the middle of the range), this method provides a simple, quick, cost-effective, and selective alternative to the conventional methodology based on Jaffé's reaction.

A new version of molecular clip, with a semi-rigid symmetrical crab-type architecture and flexible cavity size, has been successfully designed and synthesized via a one-pot Friedel-Crafts alkylation reaction. The X-ray single-crystal diffraction data provide a simple and intuitive explanation, not only for its well-preorganized and regulated conformation but also for its selective and tunable guest-binding capability. For the first time, the newly designed molecular clip was demonstrated to be not only a controllable variable-speed nonporous adsorption material in solution iodine capture, but also capable of on-off switching in volatile iodine capture. The presented new concept of molecular crystal gearshift directly from the molecular clip crystals represents an important advance in the development of synthetic receptor chemistry, which will exert a significant influence on small-molecule crystallography.

The rapid developments of quantum dots (QDs)-based nanoagents for imaging tumor and tracking drug delivery have been proven to be reliable nanodiagnostic techniques. Although abundant types of QD nanoagents have been developed for fighting against cancer, it still is a challenge to control their quality and achieve prefect repetition due to the complicated synthetic steps. The precise intermolecular self-assembly (SA) may afford a facile and low-cost strategy for this challenge. Herein, a pH and H 2 O 2 dual-sensitive Sb-cyclodextrin (CD)-doxorubicin (DOX) molecule was designed to construct a QD-based theranostic prodrug (named as Sb-CD-DOX-ZAISe/ZnS) via host-guest strategy (1st SA strategy), in which QDs water-transfer and drug-uploading were integrated well. That is, the nano-prodrug (NPD) inherited highly luminescent properties from "host" QDs for bioimaging, as well as environment sensitivities from "guest" Sb-CD-DOX for drug release. Experimental results indicate that the Sb-CD-DOX-ZAISe/ZnS exhibited effectively passive tumor-targeting and could provide clear imaging for malignant tumors in metaphase or advanced stages; meanwhile, after coating with folic acid (FA) through electric attraction (2nd SA strategy), the final Sb-CD-DOX-ZAISe/ZnS@FA NPD showed expected pH-controlled negative-to-positive charge reversal ability and a better curative effect compared with free DOX. Hence, fabricating nanocomposites by highly efficient self-assembly strategies is favorable toward inorganic nanoparticles-based prodrug delivery system for tumor-targeting theranostic.

We report the formation of supramolecular adducts between monolayer-protected noble metal nanoclusters and fullerenes, specifically focusing on a well-known silver cluster, [Ag 29 (BDT) 12 ] 3- , where BDT is 1,3-benzenedithiol. We demonstrate that C 60 molecules link with the cluster at specific locations and protect the fragile cluster core, enhancing the stability of the cluster. A combination of studies including UV-vis, high-resolution electrospray ionization mass spectrometry, collision-induced dissociation, and nuclear magnetic resonance spectroscopy revealed structural details of the fullerene-functionalized clusters, [Ag 29 (BDT) 12 (C 60 ) n ] 3- ( n = 1-9). Density functional theory (DFT) calculations and molecular docking simulations affirm compatibility between the cluster and C 60 , resulting in its attachment at specific positions on the surface of the cluster, stabilized mainly by π-π and van der Waals interactions. The structures have also been confirmed from ion mobility mass spectrometry by comparing the experimental collision cross sections (CCSs) with the theoretical CCSs of the DFT-optimized structures. The gradual evolution of the structures with an increase in the number of fullerene attachments to the cluster has been investigated. Whereas the structure for n = 4 is tetrahedral, that of n = 8 is a distorted cube with a cluster at the center and fullerenes at the vertices. Another fullerene, C 70 , also exhibited similar behavior. Modified clusters are expected to show interesting properties.

Monitoring the dynamic change with respect to chirality and species of amino acids in bacterial peptidoglycan (PG) during cell wall biosynthesis is correlated with bacterial taxonomy, physiology, micropathology, and antibacterial mechanisms. However, this is challenging because reported methods usually lack the ability of chiral analysis with the coexistence of d- and l-amino acids in PG. Here we report a chiral sensor array for PG biosynthesis monitoring through chiral amino acid recognition. Multitypes of host molecule modified MoS 2 nanosheets (MNSs) were used as receptor units to achieve more accurate and specific sensing. By applying indicator displacement strategy, the distinct and reproducible fluorescence-response patterns were obtained for linear discriminant analysis (LDA) to accurately discriminate achiral Gly, 19 l-amino acids and the corresponding 19 d-enantiomers simultaneously. The sensor array has also been used for identifying bacterial species and tracking the subtle change of amino acid composition of PG including chirality and species during biosynthesis in different growth status and exogenous d-amino acid stimulation.

We have successfully demonstrated that the host-guest complex of carboxylated pillar[6]arene with oxaliplatin (OxPt) exhibits low cytotoxicity toward normal cells and displays higher anticancer bioactivity against colorectal cancer cells than OxPt itself. Owing to higher binding affinity of carboxylated pillar[6]arene with spermine (SPM) than that with OxPt, the encapsulated OxPt can be thoroughly released from its host-guest complex by the competitive replacement with SPM. This supramolecular chemotherapy works well both in vitro and in vivo for SPM-overexpressed cancers, such as colorectal cancer. Compared to OxPt itself, the anticancer bioactivity of this host-guest complex is further improved by about 20%. Such an improvement results from the combined effect of controlled release of OxPt from its host-guest complex and simultaneous consumption of SPM by carboxylated pillar[6]arene. It is anticipated that this supramolecular strategy may be extended to other clinical anticancer drugs for decreasing their severe side effects and improving their anticancer bioactivity, thus enriching the realm of supramolecular chemotherapy.

Stimuli responsive polymers have been extensively studied as nanocarriers for drug delivery systems (DDSs), especially those based on supramolecular interactions. Cyclodextrin (CD) is one kind of widely applied host molecule, and the host-guest interactions between CD and different counterparts can respond to different stimuli and thus can be applied as responsive linkers for polymeric DDSs. In this review, the polymeric nanocarriers based on the host-guest interactions between CD and ferrocene, azobenzene, and benzimidazole as DDSs are summarized, with redox, light, and pH sensitivity, respectively. The mechanisms for the stimuli responsive ability of the linkers, the application of them for construction of DDSs with different polymer structures, and the controlled release behaviors have been focused. In addition, the outlook and challenge of these systems are discussed.