Injectable, anti-in fl ammatory and conductive hydrogels based on graphene oxide and diacerein-terminated four-armed polyethylene glycol for spinal cord injury repair

Patients with spinal cord injury (SCI) often suffer from permanent disabilities because of the low regeneration ability of adult axons. Hydrogels can serve as the scaffolding materials to bridge the damaged tissue and facilitate endogenous axonal regeneration. Here, we report a supramolecular hydrogel made of graphene oxide and diacerein-terminated four-armed polyethylene glycol for SCI repair. The hydrogel is mechanically compliant and injectable, thus can be delivered to the SCI lesions in a minimally invasive way. As diacerein is an anti-inflammatory drug, the hydrogel loaded with free diacerein can minimize the inflammatory response and prevent the formation of inhibitory microenvironment. Moreover, the suitable conductivity of the hydrogel pro-motes the growth of neuron and the remyelination of axons. We validate the outstanding mechanical, biochemical and electric properties of the designed hydrogel in vitro and also demonstrate their successful applications in SCI repair in vivo using the rat model. We anticipate that with the advances of our understanding of the biology of SCI lesions and of the axonal growth mechanism, more sophisticated SCI repair hydrogels can be designed to fully achieve functional recovery of SCI.