Optimizing the Preparation of Silk Fibroin Nanoparticles and Their Loading with Polyphenols: Towards a More Efficient Anti-Inflammatory Effect on Macrophages.

Silk fibroin nanoparticles (SFN) have become a promising tool in drug delivery systems due to their physicochemical characteristics. SFN have shown their outstanding properties as an active vehicle for polyphenols, enhancing their antioxidant and anti-inflammatory effects on macrophages; therefore, it becomes necessary to have an easy, reproducible and scalable production method. In order to improve the production of nanoparticles, we performed direct precipitation of non-dialyzed silk fibroin solutions and evaluated the reproducibility of the method using dynamic light scattering. We also studied the loading efficiency of three different natural polyphenols using propylene glycol as a solvent. The loaded nanoparticles were fully characterized and used to treat human macrophage cells to assess the anti-inflammatory activity of these nanoparticles. The measured hydrodynamic characteristics of the SFN and the overall yield of the process showed that the new preparation method is highly reproducible and repeatable. Thus, we not only present a new scalable method to prepare silk nanoparticles but also how to improve the loading of natural polyphenolic compounds to the SFN, as well as the important anti-inflammatory effects of these loaded nanoparticles in a cell model of human macrophage cells.