Ischemic stroke is the leading cause of disability and death worldwide.Currently,the only proven treatment for ischemic stroke is restoring the cerebral blood supply.In addition,some of the tissue is damaged during the subsequent reperfusion because of the overproduction of reactive oxygen species (ROS).Furthermore,antioxidant therapies have shown promise in preclinical studies for the treatment of ischermia-reperfusion injury.However,their therapeutic efficacy has been limited because of their low bioavailability in brain.To resolve this issue,we synthesized ROS-responsive,fan-shaped dendrimer nanoparticles (NPs) and conjugated them with a blood-brain barrier (BBB)-targeting peptide,COG1410,and selvianic acid A (SA),which is an effective antioxidant in ischemic stroke.The BBB targeting peptide acts as a ligend of the nanocarrier system and penetrates the BBB through the endocytosis of the ligand receptor.The results showed that T-SA-NPs not only target and accumulate in the infarct area,they also reduce over 2 times of the infarct area and reverse the behavioral deficits in MCAO mice,which illustrates that these NPs have an effective therapeutic effect on the ischemic stroke.In addition,these NPs had no toxicity in any organs of the body.Importantly,the present study provides an altemative strategy for delivering antioxidants to the brain and achieving targeted therapy of ischemic stroke.