Cyclodextrins (CDs) are naturally occurring macromolecules widely used as excipients on pharmaceutical formulations, evidencing a large spectrum of applications in the pharmaceutical industry. Their unique ability to act as molecular containers by entrapping a wide range of guest molecules in their internal cavity makes them a remarkable excipient to improve drug apparent solubility, stability, and bioavailability, and a valuable tool for the assembly of new drug delivery systems. These features are especially useful when it comes to chemotherapy, as most of the anticancer drugs present both low permeability and reduced water solubility. Therefore, guest-host inclusion complexes offer several potential advantages not only regarding the improvement of pharmaceutical formulations characteristics but also considering the reduction of drug toxic side effects. The combination of CDs with additional technologies and materials constitutes a potential strategy towards the development of advanced and multifunctional CD-based delivery systems. Paclitaxel, curcumin, camptothecin, doxorubicin, and cisplatin are among the most studied molecules with anticancer activities and have been successfully incorporated in such nanosystems. Exciting results using CDs and CD-based delivery systems have been obtained so far, paving the way towards the attainment of intelligent delivery systems to possibly address cancer therapeutics' unmet needs. In this review, a comprehensive exposition concerning in vivo-tested CD and CD-based delivery systems for anticancer therapy is undertaken. Additionally, the authors address the multivalent functionalities of CD-based delivery systems, namely the incorporation of active target ligands, stimuli-responsiveness components, surface functionalization, or further associations with other delivery systems, aiming at improved in vivo anticancer therapies. Graphical abstract.

Cyclodextrin-based delivery systems for in vivo-tested anticancer therapies

The release of two organic guests from cucurbit[7]uril (CB7) was selectively monitored by the stoppedflow method in aqueous solutions of inorganic salts to reveal the mechanistic picture in detail. Two contrasting mechanisms were identified: The symmetric dicationic 2,7- dimethyldiazapyrenium shows a cation-independent complex dissociation mechanism coupled to deceleration of the ingression in the presence of alkali and alkaline earth cations (M$^{+n}$) due to competitive formation of CB7–M$^{+n}$ complexes. A much richer, unprecedented kinetic behaviour was observed for the ingression and egression of the monocationic and non-symmetric berberine (B$^{+}$). The formation of ternary complex B+–CB7–M$^{+n}$ was unambiguously revealed. A difference of more than two orders of magnitude was found in the equilibrium constants of Mn+ binding to B$^{+}$–CB7 inclusion complex. Large cations, such as K$^{+}$ and Ba$^{2+}$, also promoted B$^{+}$ expulsion from the ternary complex in a bimolecular process. This study reveals a previously hidden mechanistic picture and motivates systematic kinetic investigations of other host–guest systems.

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Kinetics and Mechanism of Cation-Induced Guest Release from Cucurbit[7]uril.

In the present study, E-nose, E-tongue, and headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC–MS) technology combined with Principal Component Analysis (PCA) were employed to evaluate the flavor characteristics of the volatile and the non-volatile substances generated during the enzymatic hydrolysis of the soybean meal by Alcalase. The results showed that the enzymatic hydrolysis effectively reduced the content of soybean odorous substance 1-octene-3-ol and led to better flavor. However, the excessive enzymatic hydrolysis resulted in the deterioration of the enzymatic hydrolysates flavor. In addition, both radar graph and PCA of E-tongue were able to provide the distribution of flavor substances during the enzymatic hydrolysis of the soybean meal. These results provided a theoretical basis for the improvement of the flavors of the soybean meal and its derived products.

Assessment the flavor of soybean meal hydrolyzed with Alcalase enzyme under different hydrolysis conditions by E-nose, E-tongue and HS-SPME-GC-MS.

This work investigated the effects of the addition of different concentrations (0–3.0 wt%) of β-cyclodextrin (β-CD) on the properties of wheat dough and prebaked bread. Dough tensile test results and scanning electron microscopy revealed that the addition of 0.5–1.5 wt% β-CD enhanced dough tensile strength and promoted gluten formation. The addition of 2.0–3.0 wt% β-CD, however, failed to improve gluten network formation. Fourier transform infrared spectroscopy showed that the α-helix-to-β-sheet ratios of dough samples increased as β-CD content increased. This result indicated that the protein secondary structure of the dough had changed. Fermentation rheometry illustrated that dough fermentation height, gas production volume, and gas-holding capacity increased with the addition of 0–1.5 wt% β-CD. Dough fermentation capacity decreased when the addition of β-CD exceeded 2.0 wt%. The effect of β-CD on the quality of prebaked frozen bread was also studied. The results of texture profile analysis indicated that the addition of 1.5 wt% β-CD could reduce bread hardness and increase bread crumb elasticity and resilience. The results of the C-cell test further demonstrated that the addition of 1.5 wt% β-CD could increase stomatal number and decrease pore number and pore wall thickness. These characteristics suggested that the addition of β-CD improved bread structure.

Effect of β-Cyclodextrin on the Quality of Wheat Flour Dough and Prebaked Bread

We thank King Abdullah University of Science and Technology (KAUST) and the AMPM Center for supporting this work.

Xylene isomer separations by intrinsically porous molecular materials

Cucurbit[n]urils (Q[n]s), a relatively new class of macrocyclic hosts with a rigid hydrophobic cavity and two identical carbonyl-fringed portals, have attracted much attention since the first member of the Q[n]-family, cucurbit[6]uril (Q[6]), was structurally identified in 1981 by Mock and co-workers. The interactions of the rigid cavities and negative portals of Q[n]s have resulted in the development of two almost mutually exclusive areas of study, namely Q[n]-based host–guest chemistry and Q[n]-based coordination chemistry. However, researches has revealed that Q[n]-based host–guest inclusion interactions may be influenced by metal ion coordination at the Q[n] portals, and in turn, coordination of metal ions at the Q[n] portals could be promoted by the formation of Q[n]-based inclusion host–guest complexes. Thus, this review provides an overview of related advances and achievements involving such a combination of Q[n]-based host–guest chemistry and Q[n]-based coordination chemistry, which could become an emerging branch, that is, Q[n]-based host–guest-metal ion chemistry. In particular, it could be useful in the treatment of wastewater, kinetic studies, drug delivery, the construction of novel supramolecular frameworks, metal-catalyzed reactions, recognition or response to metal cations, and so on.

Cucurbit[ n ]uril-based host–guest-metal ion chemistry: an emerging branch in cucurbit[ n ]uril chemistry

Frameworks utilizing cucurbit[n]uril-based chemistry build on the rapid developments in the fields of metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and supramolecular organic frameworks (SOFs), and as porous materials have found...

Zi Yi Hua

Papers

Cucurbit[ n ]uril-based host–guest-metal ion chemistry: an emerging branch in cucurbit[ n ]uril chemistry

Construction of cucurbit[n]uril-based supramolecular frameworks via host-guest inclusion and functional properties thereof