Multifunctional thiolated chitosan/puerarin composite hydrogels with pH/glutathione dual responsiveness for potential drug carriers.

Puerarin (PUE), a natural and biologically active isoflavone extracted from Chinese medicine Pueraria lobata, can self-assemble to form a hydrogel without other chemical modifications. However, although PUE hydrogel has pH responsivity, but it is difficult to adapt to the changeable pathological environment. Therefore, thiolated chitosan (TCS) is synthesized and hybridized with PUE hydrogel to prepare TCS/PUE composite hydrogel. The results of rheological measurement showed that the resultant composite hydrogels inherited the low loss performance of TCS hydrogel, which means that they have stronger elasticity. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images displayed that TCS/PUE composite hydrogel has a fibrous-network structure. X-Ray Diffractometer (XRD) and Fourier transform infrared spectroscopy (FT-IR) proved the existence of hydrogen bonds and disulfide bonds in the formation of composite hydrogel. Degradation experiment showed that TCS/PUE composite hydrogels have pH and glutathione (pH/GSH) dual sensitivity. Furthermore, TCS/PUE composite hydrogels exhibited multi-functionality including thixotropy, cytocompatibility, antibacterial and anti-inflammatory properties. Berberine chloride hydrate (BCH) was further used as a model drug for in vitro release study. BCH and PUE could be released cooperatively under pH/GSH dual responsivity. These results indicated that the resultant composite hydrogel has eminent pH/GSH dual responsivity and could act as a potential new intelligent drug carrier.