Using feather keratin as biocompatible and inexpensive natural biopolymer and methacrylic acid as a functional monomer, we prepared a pH-sensitive feather-keratin-based polymer hydrogel (FKPGel) with grafted copolymerization. The obtained FKPGel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The swelling behavior and pH sensitivity of the FKPGel were investigated. When the small molecule (rhodamine B) and macromolecule (bovine serum albumin) were used as model drug molecules, the FKPGel exhibited controllable release behavior in vitro, and the hydrogels had pH sensitivity. For a small molecular drug, the cumulative release rate was 97% in 24 h at pH 8.4. For macromolecular drug, the cumulative release rate reached 89% at pH 7.4. Its release behavior could be controlled by the pH value. In summary, a simple method was found to reuse disused feathers. It is a kind of pH-sensitive hydrogels to be applied in drug-delivery systems.
Superoxide anion radical (O 2•-) is a toxic reactive oxygen species (ROS). Schiff-base metal complexes have been widely studied as synthetic antioxidants to scavenge ROS. However, it is toxic and shows poor water solubility. In this work, a kind of novel water-soluble biopolymer/metal complex conjugate (HO-SAM@BSA) was prepared by binding the 4-hydroxy-salicylaldehyde amino acid Schiffbase metal complexes (HO-SAM, M = Cu, Zn, Co) with water-soluble biopolymer bovine serum albumin (BSA). The conjugates were characterized using IR, UV-Vis, circular dichroism spectra (CD), and polyacrylamide gel electrophoresis (PAGE). The results show that the structure of BSA is maintained when the binding rate (n HO-SAM: n BSA ) of amino acid Schiff-base metal complexes is 10. In addition, the O 2•-scavenging activities of resultant conjugates were determined via nitrobule tetrazolium assay method. After combining HO-SAM into BSA, the poor water-solubility of HO-SAM is improved, and the O 2•-scavenging activity of BSA increases dramatically. The conjugation HOSCCu@BSA displays excellent O 2•-scavenging activity. When the EC 50 value was 0.10 lmol/L, the analog quantity reached 41 % of natural SOD. Therefore, it can act as a bifunctional mimic of enzyme, which has a great application prospect in antioxidant drug.
Supercritical fluid extraction and expansion (SFEE) patented technology combines the advantages of both supercritical fluid extraction (SFE) and rapid expansion of supercritical solution (RESS) with on-line coupling, which makes the nanoparticle formation feasible directly from matrix such as Chinese herbal medicine. Supercritical fluid extraction is a green separation technology, which has been developed for decades and widely applied in traditional Chinese medicines or natural active components. In this paper, a SFEE patented instrument was firstly built up and controlled by LABVIEW work stations. Stearic acid was used to verify the SFEE process at optimized condition; via adjusting the preexpansion pressure and temperature one can get different sizes of particles. Furthermore, stearic acid was purified during the SFEE process with HPLC-ELSD detecting device; purity of stearic acid increased by 19%, and the device can purify stearic acid.
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