Genetically engineered silk-based core-shell cytokine/sericin/carboxychitosan composite biomaterials for enhanced...

Functional biomaterials hold great promise for future medical applications, with genetically engineered silk materials being prime candidates for constructing such biomaterials. However, a major challenge in creating functional biomaterials using genetically engineered silk materials, such as cytokine-functionalized silk materials, is the inactivation of active target cytokines during fabrication. In this study, we first fabricated an active cytokine/sericin substance (SS/CTGF) via a simple "alkali extraction + acid neutralization" method from the previously created connective tissue growth factor (CTGF)-functionalized silk material, then new functional core-shell cytokine/sericin/carboxychitosan (CH-SS/CTGF) composite biomaterial was successfully developed using SS/CTGF as a functional additive. In comparison to sericin protein utilized solely as an additive, the SS/CTGF exhibited more remarkable cell proliferative activity, manifesting a 1.6-fold increment. The CH-SS/CTGF composite biomaterial featured a porous "Core" interior and a dense pitted "Shell" exterior morphology, and had adjustable mechanical properties. Moreover, it dissolved within 2 h, enabling efficient and rapid release of active CTGF and sericin proteins, thereby promoting significant NIH/3 T3 cell proliferation and migration. Most importantly, the CH-SS/CTGF composite biomaterial showed no evident cytotoxicity or severe inflammation responses. These results suggest that the CH-SS/CTGF composite biomaterial has considerable potential for applications for wound healing and drug delivery, and may also drive the future application of genetically engineered silk as functional biomaterial.