Interpenetrating network hydrogels with high strength and transparency for potential use as external dressings

Interpenetrating polymer network (IPN) hydrogels composed of gelatin and hydroxypropyl cellulose (HPC) were prepared by successive enzymatic and chemical crosslinking approaches. The hydrogels displayed porous structure and the pore size decreased with the increase of HPC content. Due to the entanglement and interpenetrating between the two crosslinked networks, the IPN hydrogels exhibited excellent mechanical strength and light transmittance. The maximum tensile and tear strengths of the IPN hydrogels reached 3.1 and 5.2MPa, respectively. The water vapor permeability of the IPN hydrogels was within the acceptable range to maintain appropriate moisture for wound healing. The cytotoxicity evaluation indicated that the IPN hydrogels exhibited no toxicity to fibroblast cells. In addition, the hydrogels were loaded with chloramphenicol by pre-soaking in drug solutions to evaluate drug-loading capacity and in vitro release behavior. It was found that the drug loaded hydrogels could act as drug delivery devices to create microbe free microenvironment, which was advantageous for wound healing.

A Smart pH-Responsive Three Components Luminescent Hydrogel

In this study, we report a novel three-component luminescent hydrogel, which is composed of amino acid derivatives (N,N'-di valine-3,4,9,10-perylenetetracarboxylic acid, NVPD), riboflavin (RF), and melamine (MM). The three-component hydrogel is attributed to multiple hydrogen bonds and the strong π-π stacking interaction between these molecules. Based on the strong hydrogen bonding of the gelator, when the reversible process between the gel and the solution take places it changes the pH of the system from 6.1 to 10.6. In addition, green fluorescence could be the emissive of the hydrogel under 498 nm and the conversion process of the aggregation state repeated reversibly by altering the value of ambient pH. This pH-responsive luminescent gel may display potential for use in nano pH sensors.

A Thixotropic Polyglycerol Sebacate-Based Supramolecular Hydrogel as an Injectable Drug Delivery Matrix

We have developed a "self-healing" polyglycerol sebacate-polyethylene glycol methyl ether methacrylate (PGS-PEGMEMA)/α-Cyclodextrin (αCD) hydrogel which could be sheared into a liquid during injection and has the potential to quickly "heal" itself back into gel post-injection. This hydrogel was shown to be biocompatible and biodegradable and therefore appropriate for use in vivo. Furthermore, the storage and loss moduli of the hydrogels could be tuned (by varying the concentration of αCD) between a fraction of a kPa to a few 100 kPa, a range that coincides with the moduli of cells and human soft tissues. This property would allow for this hydrogel to be used in vivo with maximal mechanical compatibility with human soft tissues. In vitro experiments showed that the hydrogel demonstrated a linear mass erosion profile and a biphasic drug (doxorubicin) release profile: Phase I was primarily driven by diffusion and Phase II was driven by hydrogel erosion. The diffusion mechanism was modeled with the First Order equation and the erosion mechanism with the Hopfenberg equation. This established fitting model could be used to predict releases with other drugs and estimate the composition of the hydrogel required to achieve a desired release rate.