Complexation of p-Sulfonatocalixarenes with Local Anaesthetics Guests: Binding Structures, Stabilities, and Thermodynamic Origins

Nanotherapeutics for Alleviating Anesthesia-Associated Complications

Current management of anesthesia-associated complications falls short in terms of both efficacy and safety. Nanomaterials with versatile properties and unique nano-bio interactions hold substantial promise as therapeutics for addressing these complications. This review conducts a thorough examination of the existing nanotherapeutics and highlights the strategies for developing prospective nanomedicines to mitigate anesthetics-related toxicity. Initially, general, regional, and local anesthesia along with the commonly used anesthetics and related prevalent side effects are introduced. Furthermore, employing nanotechnology to prevent and alleviate the complications of anesthetics is systematically demonstrated from three aspects, that is, developing 1) safe nano-formulization for anesthetics; 2) nano-antidotes to sequester overdosed anesthetics and alter their pharmacokinetics; 3) nanomedicines with pharmacodynamic activities to treat anesthetics toxicity. Finally, the prospects and challenges facing the clinical translation of nanotherapeutics for anesthesia-related complications are discussed. This work provides a comprehensive roadmap for developing effective nanotherapeutics to prevent and mitigate anesthesia-associated toxicity, which can potentially revolutionize the management of anesthesia complications.

Substituent Effects on the Inclusion of 1-Alkyl-6-alkoxy-quinolinium in 4-Sulfonatocalix[n]arenes

The effect of the chain length of the alkyl and alkoxy substituents on the binding characteristics of 1-alkyl-6-alkoxy-quinolinium cations was studied using 4-sulfonatocalix[4]arene (SCX4) and 4-sulfonatocalix[6]arene (SCX6) in neutral aqueous solutions at 298 K. Isothermal calorimetric titrations showed enthalpy-controlled inclusion with 1:1 stoichiometry. The equilibrium constants of complexation were always larger for the confinement in SCX4 than in its SCX6 homologue because the better matching between the host and guest sizes allowed more exothermic interaction. The binding affinity diminished with the lengthening of the aliphatic chain of the guests in the case of the association with SCX4, but insignificant change was found for SCX6 complexes. The most substantial change in the enthalpic and entropic contributions to the driving force of complex production occurred when the alkyl chain was linked to the heterocyclic nitrogen and the number of its carbon atoms varied between 1 and 4. ¹H NMR spectra evidenced that in SCX6, the 1-alkyl-6-alkoxy-quinolinium cations could be included within the macrocycle cavity. In the case of SCX4, the quinolinium ring is always inside the host, but the alkyl chain is included within SCX4 only for a short chain length (n up to 4). In contrast, the alkoxy chain displays a very weak interaction with the cavity irrespective of the length. Because of the outward orientation from the host, the lengthening of the alkoxy substituent of the quinolinium moiety barely influenced the thermodynamics of inclusion in SCX4. Distinct linear enthalpy-entropy correlations were found for the encapsulation in SCX4 and SCX6.

Density Functional Theory and Atomic Force Microscopy Study of Oleate Functioned on Siderite Surface

Efficiently discovering the interaction of the collector oleate and siderite is of great significance for understanding the inherent function of siderite weakening hematite reverse flotation. For this purpose, investigation of the adsorption behavior of oleate on siderite surface was performed by density functional theory (DFT) calculations associating with atomic force microscopy (AFM) imaging. The siderite crystal geometry was computationally optimized via convergence tests. Calculated results of the interaction energy and the Mulliken population verified that the collector oleate adsorbed on siderite surface and the covalent bond was established as a result of electrons transferring from O1 atoms (in oleate molecule) to Fe1 atoms (in siderite lattice). Therefore, valence-electrons’ configurations of Fe1 and O1 changed into 3d6.514s0.37 and 2s1.832p4.73 from 3d6.214s0.31 and 2s1.83p4.88 correspondingly. Siderite surfaces with or without oleate functioned were examined with the aid of AFM imaging in PeakForce Tapping mode, and the functioned siderite surface was found to be covered by vesicular membrane matters with the average roughness of 16.4 nm assuring the oleate adsorption. These results contributed to comprehending the interaction of oleate and siderite.

Selective recognition of the di/trimethylammonium motif by an artificial carboxycalixarene receptor

Chemical tools that recognise post-translational modifications have promising applications in biochemistry and in therapy. We report a simple carboxycalixarene that selectively binds molecules containing di/trimethylammonium moieties in isolation, in cell lysates and when incorporated in histone peptides. Our findings reveal the potential of using carboxycalixarene-based receptors to study epigenetic regulation.

Self-assembly of amphiphilic anionic calix[4]arenes and encapsulation of poorly soluble naproxen and flurbiprofen

The ability of an anionic calix[4]arene amphiphile to aggregate and to solubilize, as a result, the poorly water-soluble drugs naproxen and flurbiprofen is described.

The effect of terminal groups of viologens on their binding behaviors and thermodynamics upon complexation with sulfonated calixarenes

The effect of terminal groups of viologens on their binding behaviors with sulfonated calixarenes was systematically studied in this study.

Solvent control in the formation of supramolecular host–guest complexes of isoniazid with p-sulfonatocalix[4]arene

The position of the anti-tuberculosis drug isoniazid inside (endo) or outside (exo) to the macrocyclic cavity of p-sulfonatocalix[4]arene can be regulated by the appropriate choice of the solvent system.

Solid-state assembly of carboxylic acid substituted pillar[5]arene and its host–guest complex with tetracaine

The first examples of carboxylic acid substituted pillar[5]arene structures in the form of its inclusion complexes with ethanol and the anesthetic drug tetracaine are reported.

Supramolecular chemistry of p-sulfonatocalix[n]arenes and its biological applications

CONSPECTUS: Developments in macrocyclic chemistry have led to supramolecular chemistry, a field that has attracted increasing attention among researchers in various disciplines. Notably, the discoveries of new types of macrocyclic hosts have served as important milestones in the field. Researchers have explored the supramolecular chemistry of several classical macrocyclic hosts, including crown ethers, cyclodextrins, calixarenes, and cucurbiturils. Calixarenes represent a third generation of supramolecular hosts after cyclodextrins and crown ethers. Easily modified, these macrocycles show great potential as simple scaffolds to build podand-like receptors. However, the inclusion properties of the cavities of unmodified calixarenes are not as good as those of other common macrocycles. Calixarenes require extensive chemical modifications to achieve efficient endo-complexation. p-Sulfonatocalix[n]arenes (SCnAs, n = 4-8) are a family of water-soluble calixarene derivatives that in aqueous media bind to guest molecules in their cavities. Their cavities are three-dimensional and π-electron-rich with multiple sulfonate groups, which endow them with fascinating affinities and selectivities, especially toward organic cations. They also can serve as scaffolds for functional, responsive host-guest systems. Moreover, SCnAs are biocompatible, which makes them potentially useful for diverse life sciences and pharmaceutical applications. In this Account, we summarize recent work on the recognition and assembly properties unique to SCnAs and their potential biological applications, by our group and by other laboratories. Initially examining simple host-guest systems, we describe the development of a series of functional host-guest pairs based on the molecular recognition between SCnAs and guest molecules. Such pairs can be used for fluorescent sensing systems, enzymatic activity assays, and pesticide detoxification. Although most macrocyclic hosts prevent self-aggregation of guest molecules, SCnAs can induce self-aggregation. Researchers have exploited calixarene-induced aggregation to construct supramolecular binary vesicles. These vesicles respond to internal and external stimuli, including temperature changes, redox reactions, additives, and enzymatic reactions. Such structures could be used as drug delivery vehicles. Although several biological applications of SCnAs have been reported, this field is still in its infancy. Continued exploration of the supramolecular chemistry of SCnAs will not only improve the existing biological functions but also open new avenues for the use of SCnAs in the fields of biology, biotechnology, and pharmaceutical research. In addition, we expect that other interdisciplinary research efforts will accelerate developments in the supramolecular chemistry of SCnAs.

Complexations of the hydrophilic and hydrophobic moieties of benzethonium chloride by cucurbit[7]uril in aqueous solution

The sequential complexations of the hydrophilic and hydrophobic end groups of benzethonium chloride by cucurbit[7]uril (CB[7]) in aqueous solution have been investigated using 1H NMR spectroscopy and electrospray ionization mass spectrometry. The initial binding is to the benzyldimethylammonium group, with a stability constant of (8.7 ± 3.1) × 107 (mol/L)–1. This binding constant and the complexation-induced upfield shifts of the benzyl guest protons are similar to those values observed with other cationic guests containing benzyl moieties. This equilibrium is followed by the binding of a second equivalent of the host to the hydrophobic 2-(2,4,4-trimethylpentyl) group, with a stability constant of (4.0 ± 1.9) × 103 (mol/L)–1. The relatively strong binding of this uncharged hydrophobic end of the guest molecule is consistent with the inclusion of eight heavy (nonhydrogen) atoms within the inner cavity of CB[7], with its low polarizability. The packing coefficient for the 2-(2,4,4-trimethylpentyl) group with the inner cavity is calculated to be 61%, close to Rebek’s ideal value of 55%.