Fabrication of silk fibroin peptide-astaxanthin nanocomposites by nanoprecipitation for enhanced stability and antioxidant activity.

Astaxanthin (AST), a potent antioxidant, suffers from poor stability and low solubility, limiting its applications across various fields. To address these issues, this study aims to develop a silk fibroin peptide-astaxanthin (SFP-AST) nanocomposite using a simple nanoprecipitation method. Characterization techniques such as Ultraviolet-visible spectroscopy (UV-vis), fluorescence spectroscopy, circular dichroism (CD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform Infrared (FTIR) confirmed that SFP stabilizes AST in nanoparticles ranging in size from 150 to 300 nm. Stability testing showed that under alkaline shock conditions, the retention rate of AST in the nanocomposite was 55.6%, whereas the retention rate in the free AST solution was only 43.6%. After 24 h of storage, the retention rate of AST in the nanocomposite was 44.4%, whereas the retention rate in the free AST solution was only 30.8%. Furthermore, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays revealed that the SFP-AST nanocomposite exhibited a 62.40% radical scavenging activity, compared to 38.11% for free AST. These results suggest that silk fibroin peptides can effectively stabilize and enhance AST, offering a natural, biocompatible carrier with broad potential applications in functional foods, dietary supplements, and cosmetics.