Mechanical cues are critical regulators of cell fate and behavior through the orchestrated and continual conversion of physical forces into biochemical responses. However, due to the poor compatibility between mechanical and biochemical techniques, existing methods are often limited in characterizing the occurring biochemical signals during mechanical stimulation. Herein, this work presents a magneto-responsive nanomesh (MRnM) biosensor capable of mechanically stimulating cells in vitro and tissues in vivo and simultaneously detecting the triggered biomolecules. Under external magnetic fields, the sensor exhibits excellent magnetic responsiveness with remote, controllable and tailored deformation, while maintaining prominent and stable electrochemical sensing performance. As a proof of concept, this MRnM sensor achieves the magnetically-actuated deformation of osteoblasts and real-time monitoring of the ensuing nitric oxide release, revealing the role of Piezo1 channels in nitric oxide synthase signaling pathways. Furthermore, we demonstrate the capability of MRnM sensor for in vivo applications. Ultimately, the developed MRnM biosensor holds great potential for mechanical stimulation and real-time monitoring of various biological systems, ranging from living cells to soft tissues and in vivo organs.
Biomechanical stimuli derived from the extracellular matrix (ECM) extremely tune stem cell fate through three-dimensional (3D) and spatiotemporal changes in vivo. The matrix stiffness as a crucial factor during bone tissue development is dynamic stiffening. However, most in vitro models to study the osteogenesis of mesenchymal stem cells (MSCs) are static or stiffening in a 2D environment. Here, we create a dynamic and controllable stiffening 3D biomimetic model to regulate the osteoblastic differentiation of MSCs with a dual-functional gelatin macromer that can generate a double-network hydrogel by sequential enzymatic and light-triggered crosslinking reactions. Our findings showed that these dynamic hydrogels allowed cells to spread and volume expansion prior to secondary crosslinking and to sense high stiffness after stiffening. The MSCs in the dynamic hydrogels, especially the hydrogel stiffened at the late period, presented the significantly elevated osteogenic ECM secretion, gene expression, and YAP/TAZ nuclear localization. In vivo evaluation of animal experiments further indicated that the enhancement of dynamic stiffening on osteogenesis of MSCs substantially promoted bone remodeling. Consequently, this work reveals that the 3D dynamic stiffening microenvironment as a critical biophysical cue not only mediates the stem cell fate in vitro, but also augments bone restoration in vivo. This article is protected by copyright. All rights reserved
危险品化学品经营许可证（带存储）