Optimizing protein delivery rate from silk fibroin hydrogel using silk fibroin-mimetic peptides conjugation.

Controlled release of proteins, such as growth factors, from biocompatible silk fibroin (SF) hydrogel is valuable for its use in tissue engineering, drug delivery, and other biological systems. To achieve this, we introduced silk fibroin-mimetic peptides (SFMPs) with the repeating unit (GAGAGS)n. Using green fluorescent protein (GFP) as a model protein, our results showed that SFMPs did not affect the GFP function when conjugated to it. The SFMP-GFP conjugates incorporated into SF hydrogel did not change the gelation time and allowed for controlled release of the GFP. By varying the length of SFMPs, we were able to modulate the release rate, with longer SFMPs resulting in a slower release, both in water at room temperature and PBS at 37 °C. Furthermore, the SF hydrogel with the SFMPs showed greater strength and stiffness. The increased ß-sheet fraction of the SF hydrogel, as revealed by FTIR analysis, explained the gel properties and protein release behavior. Our results suggest that the SFMPs effectively control protein release from SF hydrogel, with the potential to enhance its mechanical stability. The ability to modulate release rates by varying the SFMP length will benefit personalized and controlled protein delivery in various systems.

Syntheses of quinazolinones from 2-iodobenzamides and enaminones via copper-catalyzed domino reactions.

N-Substituted 2-iodobenzamides and enaminones undergo cascade transformations to achieve quinazolinones via a copper-catalyzed Ullmann-type coupling, a Michael addition and a retro-Mannich reaction. A unique stereochemical feature of this domino process was that Z-enaminones reacted without external ligands, whereas E-enaminones required the assistance of ligands.