Cyclodextrin nanosponge for the GSH-mediated delivery of Resveratrol in human cancer cells

Smart drug delivery systems are required for the site-specific drug targeting to enhance the therapeutic efficiency of a drug. Resveratrol (RV) is a polyphenolic compound with anti-cancer activity. However, its poor aqueous solubility and non-selectivity are the major challenges for its employment in cancer therapy. In this work, we present the synthesis of RV-loaded glutathione responsive cyclodextrin nanosponges (RV-GSH-NSs) to improve the therapeutic efficiency and selective delivery of RV. The drug loading and encapsulation efficiency were 16.12% and 80.64%, respectively. The in vitro release profile confirmed that RV release was enhanced in response to external glutathione (GSH). Nude NSs were not toxic per se to human fibroblasts when administered for up to 72 h at the highest dose. Cell internalization studies confirmed that RV-GSH-NSs were preferentially up-taken by tumor cells compared to non-tumorigenic cells. Accordingly, RV showed selective toxicity to cancer cells compared to normal cells. GSH depletion by buthionine sulfoximine, a potent inhibitor of its synthesis, reflected in a significant decrease of the NSs accumulation, and consequently resulted in a drastic reduction of RV-mediated toxic effects in cancer cells. These findings demonstrate that GSH- responsive NSs represent an effective delivery system for targeting cancer cells by harnessing the differential tumor characteristics in terms of redox status in parallel with the limitation of side effects toward normal cells.

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

Cyclodextrin nanosponges (CD-NS) are nanostructured crosslinked polymers made up of cyclodextrins. The reactive hydroxy groups of CDs allow them to act as multifunctional monomers capable of crosslinking to bi- or multifunctional chemicals. The most common NS synthetic pathway consists in dissolving the chosen CD and an appropriate crosslinker in organic polar aprotic liquids (e.g., N,N-dimethylformamide or dimethyl sulfoxide), which affect the final result, especially for potential biomedical applications. This article describes a new, green synthetic pathway through mechanochemistry, in particular via ball milling and using 1,1-carbonyldiimidazole as the crosslinker. The polymer obtained exhibited the same characteristics as a CD-based carbonate NS synthesized in a solvent. Moreover, after the synthesis, the polymer was easily functionalized through the reaction of the nucleophilic carboxylic group with three different organic dyes (fluorescein, methyl red, and rhodamine B) and the still reactive imidazoyl carbonyl group of the NS.

Study of oxyresveratrol complexes with insoluble cyclodextrin based nanosponges: Developing a novel way to obtain their complexation constants and application in an anticancer study

The complexation of the bioactive compound oxyresveratrol (OXY) with a polymer called cyclodextrin-based nanosponge (CD-NS) and its application was studied.A new methodology is used to calculate, an apparent inclusion complex constant (K_Fapp) between a ligand and CD-NSs. Moreover, the K_Fapp of resveratrol was also evaluated and compared. The complex of OXY with the nanosponge β-CDI 1:4, was studied in vitro using DSC, TGA and FTIR techniques and its drug loading and release behavior were studied. An in vitro digestion showed higher protection of OXY complexed than free OXY. The bioactivity enhancing capacity of OXY was also studied against prostate (PC-3) and colon (HT-29 and HCT-116) cancer cell lines, where it showed stronger cell viability inhibition than the free drug. The findings as a whole represent a new opportunity for studying the complexation of drugs in CD-NSs and the use of oxyresveratrol as an ingredient in nutraceutical products.

Eco-Friendly β-cyclodextrin and Linecaps Polymers for the Removal of Heavy Metals

Environment-friendly nanosponges, having a high content of carboxyl groups, were synthesized by crosslinking β-cyclodextrin and linecaps, a highly soluble pea starch derivative, with citric acid in water. Additionally, pyromellitic nanosponges were prepared by reacting β-cyclodextrin and linecaps with pyromellitic dianhydride in dimethyl sulfoxide and used in comparison with the citric nanosponges. After ion-exchange of the carboxyl groups H⁺ with sodium ions, the ability of the nanosponges to sequester heavy metal cations was investigated. At a metal concentration of 500 ppm, the pyromellitate nanosponges exhibited a higher retention capacity than the citrate nanosponges. At lower metal concentrations (≤50 ppm) both the citrate and the pyromellitate nanosponges showed high retention capacities (up to 94% of the total amount of metal), while, in the presence of interfering sea water salts, the citrate nanosponges were able to selectively adsorb a significantly higher amount of heavy metals than the pyromellitate nanosponges, almost double in the case of Cu²⁺.