Novel Double Phase Transforming Organogel Based on β-Cyclodextrin in 1,2-Propylene Glycol

Heat-Set Supramolecular Hydrogelation by Regulating the Hydrophilic-Lipophilic Balance for a Tunable Circularly Polarized Luminescent Switch

Heat-set supramolecular gels exhibited totally opposite phase behaviors of dissolution upon cooling and gelation on heating. They are commonly discovered by chance and their rational design remains a great challenge. Herein, a rational design strategy is proposed to realize heat-set supramolecular hydrogelation through regulation of the hydrophilic-lipophilic balance of the system. A newly synthesized amphiphile hydrogelator with pyrene embedded in its lipophilic terminal can self-assemble into a hydrogel through a heating and cooling cycle. However, the host-guest complex of the gelator and hydrophilic γ-cyclodextrin (γ-CyD) results in a sol at room temperature. Thus, heat-set hydrogelation is realized from the sol state in a controllable manner. Heat-set gelation mechanism is revealed by exploring critical heat-set supramolecular gelation and the related findings provide a general strategy for developing new functional molecular gels with tunable hydrophilic-lipophilic balance.

Supramolecular organogel formation through three-dimensional α-cyclodextrin nanostructures: solvent chirality-selective organogel formation

Novel supramolecular organogels were efficiently formed by mixing a 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solution of α-cyclodextrin (α-CD) with 1- or 2-butanol via the formation of three-dimensional hexagonal nanostructures composed of head-to-tail α-CD channel assemblies. Mixing (R)- and (S)-2-butanol with an α-CD/HFIP solution realized (S)-2-butanol-selective organogel formation.

Thermo-triggerable self-assembly comprising cinnamoyl polymeric β cyclodextrin and cinnamoyl Pluronic F127

Thermo-triggerable self-assembly was prepared by co-dissolving cinnamoyl Pluronic F127 (CinPlu) and cinnamoyl polymeric β cyclodextrin (CinPβCD) in an aqueous phase. On TEM photo, the CinPlu/CinPβCD self-assembly was 100-200nm in diameter. The specific loading of Nile red (NR) in the assembly was calculated to be 5.5% (wt NR/wt polymer), and the molar ratio of NR to βCD residue in the assembly was about 0.89:1. No significant release of NR from the assembly was observed at 10°C and 20°C. However, when the temperature was raised to 30°C, 40°C, 50°C, and 60°C, the cumulative release amount in 5min was 17%, 25%, 32%, and 52%, respectively. The specific loading of doxorubicin (DOX) in the assembly was about 6.8% (wt DOX/wt polymer) (corresponding to the molar ratio of DOX to βCD residue was about 0.41:1). The DOX release from the assembly was proportional to the temperature of release medium. NR and DOX were likely to be expelled out of the cavity of βCD residue by the interaction of the thermally hydrophobicized Pluronic F127 chain (molecular piston) and the cavity of βCD residue (cylinder). After 4h-incubation with KB cell, DOX loaded in CinPlu/CinPβCD self-assembly was found to be internalized into the cancer cell more than free DOX, observed on a confocal laser scanning microscope and a fluorescence activated cell sorter. CinPlu/CinPβCD self-assembly enhanced the in vitro anti-cancer activity of DOX against KB cell without increasing significantly the in vitro toxicity of DOX against Raw264.7 cell.

Characterization of supramolecular gels based on β-cyclodextrin and polyethyleneglycol and their potential use for topical drug delivery

Novel gels were prepared by blending β-cyclodextrin and polyethyleneglycol (PEG) in the presence of K2CO3. The objective of this study was thus to characterize the gels using rheology, modulated temperature differential scanning calorimetry (MTDSC), turbidity measurements, and hot stage microscopy, and then investigate the potential use of the gel for topical drug delivery. Two types of supramolecular gels, GelL and GelH were prepared at a low temperature (below 50 °C) and at a high temperature (above 70 °C), respectively. Both gels were thermo-reversible. Upon heating, GelL could turn to GelH. Nevertheless, upon cooling, GelH that was more stable than GelL precipitated and GelL could not be reformed. GelL may form through simple complexation of polyethyleneglycol (PEG) with β-cyclodextrin in the presence of K2CO3. However, GelH may form a specific complex or a pseudopolyrotaxane gel. For pharmaceutical application, GelL was investigated instead of GelH because the forming temperature of this gel was close to the human body temperature. The interactions among diclofenac sodium (DS), a model drug, and the components of the gel were examined using FTIR. These interactions may include ionic attraction and hydrogen bonds between the carboxylate groups of DS and the hydroxyl groups of PEG or β-cyclodextrin and probably also the inclusion of the aromatic ring of DS into the cavity of β-cyclodextrin. Furthermore, the release and permeation of diclofenac from GelL were significantly greater than those from a commercial gel. Therefore, GelL may be useful for the topical delivery of drugs.

Supramolecular cyclodextrin-based drug nanocarriers

Hosting of polymers, lipids and drug conjugates makes cyclodextrins suitable to prepare biocompatible, targetable and stimuli-responsive supramolecular drug nanocarriers.

Controllable self-assemblies of sodium benzoate in different solvent environments

Sodium benzoate is an important and widely used food additive, however, it's self-assembly properties in diverse solvents have been rarely studied. Here, we systematically report its various self-assemblies in different solvents environments.

Chemometric and Experimental Investigations of Organogelation Based on β-Cyclodextrin

The evaluation of PEG as a gelation solvent for an organogel based on β-cyclodextrin (β-CyD) was investigated using principal component analysis (PCA). The test tube tilting method was performed to examine the gel formation experimentally. The important descriptors used in the PCA included the Hansen partial solubility parameters. LogP may be able to be used as an additional descriptor for this system. According to PCA analysis, PEG was in a cluster of gelation solvents. Subsequently, various PEG liquid state grades were tested for their ability to gel the system and PEG400 was found to be able to produce a gel. This verifies that PCA can be successfully used to evaluate the role of PEG. Accordingly, this PCA method may be an effective tool to evaluate the role of any solvent for other low molecular weight gelators (LMWGs). Afterwards, the optimal components in the system were explored, and it was found to be 0.1M β-CyD, 0.5M K2CO3 in PEG400. Based on WAXS, the gel fiber of this organogel was demonstrated to be amorphous. This forming organogel will be further characterized in details and investigated for use in a drug delivery system.