Tailoring a UCST-LCST-pH Multiresponsive Window through a Single Polymer Complex of Chitosan-Hyaluronic Acid

Multistimuli-responsive polymers are important for controlled release. Owing to the fact that these polymers are derived from vinyl-based monomers, their decoration with other molecules is limited. Polysaccharides, especially chitosan (CS) and hyaluronic acid (HA), are pH-responsive biopolymers, whose chemical structures contain reactive functional groups for feasible chemical modifications to obtain add-on functions. The present work demonstrates the introduction of polymers with upper critical solution temperature (UCST) and lower critical solution temper-ature (LCST) performances onto CS and HA, respectively. By simply varying the mole ratio between the CS-containing UCST polymer and the HA-containing LCST polymer along with adjusting the pH, a polymer system with a UCST-LCST-pH multiresponsive window can be obtained. This multiresponsive window enables us to control the encapsulation and release with repeatability as evidenced from a model study on lysozyme. The present work, for the first time, shows a simple approach to obtain multiresponsive biodegradable polymers through the formation of a single polymer complex to tailor a specific multiresponsive window.

Automated summary

Multistimuli-responsive polymers are important for controlled release, but their decoration is limited due to their derivation from vinyl-based monomers. In this study, polymers with different critical solution temperatures were introduced onto chitosan and hyaluronic acid, resulting in a polymer system with a multiresponsive window. By adjusting the mole ratio and pH, the encapsulation and release of lysozyme were controlled repeatably.