ß-Cyclodextrin-modified hyaluronic acid-based supramolecular self-assemblies for pH- and esterase- dual-responsive drug delivery.

Although some drug-based supramolecular systems have been constructed to overcome multidrug resistance and enhance the bioavailability of chemical drugs, strengthening the specific stimuli-responsive and active targeting ability of these systems is still a major challenge. In this paper, the synthesis and self-assembly behaviour of supramolecular self-assemblies with active targeting ß-cyclodextrin-modified hyaluronic acid (HA-CD) and drug-drug conjugates (curcumin-oxoplatin, Cur-Pt) as building moieties were carefully investigated. Notably, the curcumin was chosen not only as the chemical anti-cancer drug, but also acted as the guest molecule which could be included into CD cavity to form host-guest interaction-based supramolecular assemblies. The obtained self-assemblies exhibited pH- and esterase-responsive drug release behaviours. Furthermore, basic cell experiments were performed to prove their effective cellular toxicity based on A549 cells and PC3 cells with high expression of CD44 receptor but they showed no toxicity to normal LO-2 cells with low expression of CD44 receptor, which suggests their potential application in the targeted drug release field.

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB2-type host-guest-conjugated amphiphilic molecules for controlled drug delivery.

Although stimuli-responsive supramolecular self-assemblies have been constructed, the controlled drug delivery induced by morphology transitions of these supramolecular self-assemblies on the basis of host-guest-conjugated monomers (HGCMs) are few reported. In this paper, the self-assembly behaviors of AB2-type HGCMs, e.g., ß-cyclodextrin-benzimidazole2 (ß-CD-BM2), were investigated at neutral and acidic pH conditions, respectively. Specifically, ß-CD-BM2 first self-assembled into fan-shaped supramolecular self-assemblies with a hydrodynamic diameter of 163 nm at neutral pH, whereas they were further dissociated into spherical supramolecular self-assemblies with a size of 52 nm under acidic conditions. This morphology transition process was utilized to conduct a two-stage DOX delivery under neutral and acidic pH. Basic cell experiments demonstrated that the drug-loaded ß-CD-BM2-based supramolecular self-assemblies with varied morphology could inhibit cancer cell proliferation, indicating their potential application in the field of drug delivery.

Cross-linked succinyl chitosan as an adsorbent for the removal of Methylene Blue from aqueous solution.

Removal of a basic dye (Methylene Blue) from aqueous solution was investigated using a cross-linked succinyl-chitosan (SCCS) as sorbent. The chemical structures of chitosan and its derivatives were testified by FT-IR. X-ray diffraction, DTG analysis and swelling measurements were conducted to clarify the characteristics of the chemically modified chitosan. The effect of process parameters, such as pH of the initial solution, and concentrations of dyes on the extent of Methylene Blue (MB) adsorption was investigated. The Langmuir isotherm model was used to fit the equilibrium experimental data, giving a maximum sorption capacity of 289.02 mg/g at 298 K. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were determined to be -25.32 kJmol(-1), -6.76 kJmol(-1) and -62.36 Jmol(-1) K(-1), respectively, which leads to a conclusion that the adsorption process is spontaneous and exothermic.

Chemical modification of chitosan by tetraethylenepentamine and adsorption study for anionic dye removal.

To utilize the contribution of introduced amino groups to the adsorption of an anionic dye (eosin Y), a batch adsorption system was applied to study the adsorption of eosin Y from aqueous solution by tetraethylenepentamine (TEPA) modified chitosan (TEPA-CS). Experiments were carried out as a function of particle size, initial pH, agitation rate, adsorbent dosage, agitation period, temperature and initial concentration of eosin Y. The Langmuir and Freundlich models were used to fit the adsorption isotherms. From the values of correlation coefficients (R2), it was observed that the experimental data fit very well to the Langmuir model, giving a maximum sorption capacity of 292.4mg/g at 298K. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. The thermodynamic study revealed negative value of enthalpy change (ΔH°) and free energy change (ΔG°), indicating spontaneous and endothermic nature of the adsorption of eosin Y on to TEPA-CS.