ERBB3 and brain neoplasm: PET/MRI and fluorescenceimaging were utilized to investigate thedistribution of the nanomedicines in the brain in vivo and ex vivo.The results demonstrated the localization of both untargeted and HER3-targetedHBP-DOX in brain tumors region relative to uninvolved brain region.Additionally, the ex vivo fluorescent brain imaging revealed thatHER3-targeted HBP-DOX has 14-fold more intracranial accumulation thanuntargeted HBP-DOX highlighting the advantage of the active targetingapproach in enhancing drug delivery to brain tumors.