Glucose-Triggered Release of trans-N-p-Coumaroyltyramine from Zeolitic Imidazolate Framework-8 (ZIF8) Modified with Dioscorea opposita Thunb Polysaccharide.

A Dioscorea opposita Thunb polysaccharide (DOP)-modified ZIF8 material was developed in this study, which can be used as a "smart" glucose-responsive carrier to control the slow release of drugs. The 3-aminophenylboronic acid (APBA) functionalized carboxylated long-chain polymer poly(ethylene glycol) (PEG) segments, which were first modified on the surface of ZIF8 nanoparticles with a hydrogen bond and then chemically cross-linked with DOP through a borate ester bond, leading to the drugs loaded on ZIF8 being "closed" in PBS but being "open" via taking off the DOP coating in high concentrations of glucose; thus, leakage can be prevented in the drug loaded and a glucose-triggered release can effectively result. Moreover, the materials showed good biocompatibility and the released trans-N-p-coumaroyltyramine (NCT) could work synergistically with the DOP to improve insulin resistance and promote glucose consumption in insulin-resistant HepG2 cells.

Carbon Dots Embedded Hybrid Microgel with Phenylboronic Acid as Monomer for Fluorescent Glucose Sensing and Glucose-Triggered Insulin Release at Physiological pH.

A multifunctional and biocompatible hybrid microgel (poly(VPBA-AAm)-CD) using N, S-doped carbon dots (CDs) and ethylene glycol dimethacrylate (EGDMA) as cross-linking agents, and 4-vinylbenzene boronic acid (VPBA) and acrylamide (AAm) as monomers, was designed in this work. This microgel can be easily prepared by a simple one-pot radical dispersion polymerization of the reactants using a rationally designed hydrogen-bonded complex method. The hybrid microgels were spherical particles with a smooth surface and an average particle size of 234 ± 8 nm. The poly(VPBA-AAm)-CD microgel displayed the glucose-responsive swelling within a clinically concerned range at a physiological pH and could realize the controllable release of insulin. In addition, the release rate of insulin in the hybrid microgel (poly(VPBA-AAm)-CD) could be triggered by glucose concentrations in the solution, and the increasing glucose concentrations can accelerate the insulin release. Further in vitro cytotoxicity studies showed that the microgel had good biocompatibility and no obvious toxicity to the cells. These indicate that the prepared microgel (poly(VPBA-AAm)-CD) may supply a new pattern for the self-regulating therapy of insulin deficiency in diabetes.

A Dioscorea opposita Thunb Polysaccharide-Based Dual-Responsive Hydrogel for Insulin Controlled Release.

A novel hydrogel (DOP/PEI-PBA) based on the "three-component" reaction of 2-formylphenylboric acid (2-FPBA), the primary amine group of polyethyleneimine (PEI) and the cis-o-dihydroxy groups of Dioscorea opposita Thunb polysaccharide (DOP) was designed in this work. The hydrogel can be easily prepared by simply mixing the three reactants at room temperature. The hydrogel had dual responsiveness to glucose and pH, and can realize the controllable release of insulin. Moreover, the hydrogel combining insulin and DOP can inhibit the reactive oxygen species (ROS) level and malondialdehyde (MDA) content, and promote glucose consumption as well as the level of superoxide dismutase (SOD), in high-glucose-induced injury in HL-7702 cells, which reflects the synergistic effect of insulin and DOP to protect hepatocytes from oxidative stress at the same time. Further in vitro cytotoxicity studies showed that the hydrogel had good biocompatibility and no obvious toxicity to cells. These indicate that the prepared hydrogel (DOP/PEI-PBA) can be expected to be applied in the clinical treatment of insulin deficiency in diabetes.