Dual stimuli responsive poly(N-isopropylacrylamide-co-acrylic acid) hydrogels based on a β-cyclodextrin crosslinker: synthesis, properties, and controlled protein release

Role of thermal and reactive oxygen species-responsive synthetic hydrogels in localized cancer treatment (bibliometric analysis and review)

Cancer is a major pharmaceutical challenge that necessitates improved care.

pH-responsive nanomicelles of poly(ethylene glycol)-poly(ε-caprolactone)-poly(L-histidine) for targeted drug delivery

Here, a novel pH-responsive block copolymer, poly (ethylene glycol)-poly(ε-caprolactone)-poly(L-histidine) (PEG-PCL-PHis), was synthesized and designed for anti-cancer drug delivery with excellent biocompatible, biodegradable, and strong drug loading efficiency. ¹H-NMR, IF-IR, and GPC were used to characterize the structure of the PEG-PCL-PHis copolymer. In addition, the morphology, particle size, Zeta potential, and critical micelle concentration (CMC) of different degree of polymerization were determined by transmission electron microscopy (TEM), dynamic light scattering granulometer (DLS), and fluorescence spectrometer, respectively. The strong affinity between the core of micelles and hydrophobic drug was manifested with 15.09% drug loading content and 84.65% entrapment efficiency. In vitro release of DOX from the block copolymer micelle demonstrated, the PEG-PCL-PHis copolymer micelle has stable and durable drug releasing ability accompanied with pH-sensitivity. From the mechanism of cellular uptake the micelles, the pathway of drug release was captured by confocal laser scanning microscope. These experiments demonstrated the safe delivery for anticancer medicine through this novel copolymer. In conclusion, the PEG-PCL-PHis copolymer micelle has great potential to become a safe drug carrier for cancer chemotherapy.

Investigating structure-dependent diffusion in hydrogels using spatially resolved NMR spectroscopy

HYPOTHESIS

Incorporation of the drug-loaded surfactant micelles into polymer hydrogels is a common method used to achieve controlled drug delivery. The characterization of the diffusion processes in drug delivery systems is critical in order to tune the drug loading and release.

EXPERIMENTS

We present a simple and efficient NMR protocol to investigate the transport of the surfactant molecules in hydrogels on micro- and macroscale under non-equilibrium conditions. Our experimental protocol is based on a combination of ¹H 1D NMR chemical shift imaging and slice-selective diffusion experiments, which enables determination of the mutual and self-diffusion coefficients of the surfactant in the non-equilibrium hydrogel-based system within the same short time frame.

FINDINGS

Our results show that the self-diffusion coefficient of the positively charged surfactant in the hydrogel (D_s^gel) decreases with the increasing surfactant concentration until it reaches a plateau value of 6.6±0.5×10^-11m²s^-1. The surfactant self-diffusion in the solution (D_s^sln) remains constant over the experiment with an average value of 6.7±0.3×10^-11m²s^-1. The surfactant mutual diffusion coefficient obtained from 1D chemical shift imaging in this hydrogel system (D_m) is 7.7±0.5×10^-11m²s^-1. Correlation of the localized D_s to the 1D chemical shift images gives insight into the structure-dependent diffusional behavior of surfactant molecules in the hydrogel. This NMR protocol will be of great value in studies of concentration dependent structures on the interfaces between two immiscible liquids.

Acrylated Composite Hydrogel Preparation and Adsorption Kinetics of Methylene Blue

By using cyclodextrin (α-CD) self-assembly into a hydrogel with the triblock copolymer Pluronic F127, nanomicrocrystalline cellulose was introduced into a gel system to form a composite CNC-β-CD/α-CD/Pluronic F127 hydrogel (CCH). CCH was modified further by grafting acrylic acid to form a novel acrylated composite hydrogel (ACH). The swelling degree of ACH was 156 g/g. Adsorption isotherms show that the adsorption process for methylene blue proximity fitted the Freundlich model. The adsorption kinetics showed that ACH followed a quasi-second-order kinetic model. Methylene blue desorption showed that ACH was a temperature- and pH-dependent gel. Repeated adsorption and desorption experiments were carried out three times, and the removal rate of methylene blue at 75 mg/L was still 70.1%.