Stroke is the second leading cause of death globally and the most common cause of severe disability. Several barriers need to be addressed more effectively to treat
stroke, including efficient delivery of therapeutic agents, rapid release at the
infarct site, precise imaging of the
infarct site, and drug distribution monitoring. The present study aimed to develop a bio-responsive
theranostic nanoplatform with signal-amplifying capability to deliver
rapamycin (RAPA) to ischemic brain tissues and visually monitor drug distribution. A pH-sensitive
theranostic RAPA-loaded nanoparticle system was designed since ischemic tissues have a low-pH microenvironment compared with normal tissues. The nanoparticles demonstrated good stability and biocompatibility and could efficiently load
rapamycin, followed by its rapid release in acidic environments, thereby improving therapeutic accuracy. The
nano-drug-delivery system also exhibited
acid-enhanced magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) imaging signal properties, enabling accurate multimodal imaging with minimal background noise, thus improving drug tracing and diagnostic accuracy. Finally, in vivo experiments confirmed that the nanoparticles preferentially aggregated in the ischemic hemisphere and exerted a
neuroprotective effect in rats with transient
middle cerebral artery occlusion (tMCAO). These pH-sensitive multifunctional
theranostic nanoparticles could serve as a potential nanoplatform for drug tracing as well as the treatment and even diagnosis of
acute ischemic stroke. Moreover, they could be a universal
solution to achieve accurate in vivo imaging and treatment of other diseases.