Timely and spatially-regulated injectable hydrogels, able to suppress growing tumors in

response to conformational transitions of proteins, are of great interest in cancer research

and treatment. Herein, we report rapidly responsive silk fibroin (SF) hydrogels formed by a

horseradish peroxidase (HRP) crosslinking reaction at physiological conditions, and demonstrate

their use as an artificial biomimetic three-dimensional (3D) matrix. The proposed SF

hydrogels presented a viscoelastic nature of injectable hydrogels and spontaneous conformational

changes from random coil to β-sheet conformation under physiological conditions.

A human neuronal glioblastoma (U251) cell line was used for screening cell encapsulation

and in vitro evaluation within the SF hydrogels. The transparent random coil SF hydrogels

promoted cell viability and proliferation up to 10 days of culturing, while the crystalline SF

hydrogels converted into β-sheet structure induced the formation of TUNEL-positive apoptotic

cells. Therefore, this work provides a powerful tool for the investigation of the microenvironment

on the programed tumor cells death, by using rapidly responsive SF hydrogels as

3D in vitro tumor models.