Preparation of FK-SA conjugate gel beads with double cross-linking for pH-controllable drug releasing

Using feather keratin (FK), a kind of biocompatible natural polymer being extracted from widely available and renewable waste feathers, and sodium alginate (SA) as materials, the FK conjugated SA gel beads (FK-SA-Gbs) were prepared with double cross-linked by calcium ion (Ca 2+ ) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). After being characterized and analyzed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), its pH responsiveness, salt ion responsiveness, and degradability were measured, and the loading capacity of model drug Rhodamine B (RhB) under various physical conditions, the cumulative release rate of the loaded gel beads in different pH buffer solutions were also investigated. The results showed that the FK-SA-Gbs had significant pH sensitivity and sustained release, and various physical conditions can meet the requirements of wound dressings. It indicated FK-SA-Gbs can be used as controlled release drug carriers and are expected to be used as drug carrier materials in biomedical applications. Graphical abstract FK conjugated SA gel beads (FK-SA-Gbs) was prepared by secondary cross-linking with CaCl 2 and 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC/HCl) using feather keratin (FK) extracted from waste feathers, which have significant pH sensitivity and sustained release capability.