Statement of Purpose: Poly(ethylene glycol)-bl-poly(propylene sulfide) (PEG-bl-PPS) (Fig 1a) is a versatile block copolymer system capable of forming nanocarriers of various morphologies such as micelles (MCs), polymersomes (PSs), and most recently bicontinuous nanospheres (BCNs)1,2. These nanocarriers have been used to deliver hydrophobic and hydrophilic therapeutics to different target tissues and cells based on particle morphology1,3. To enhance targeting and drug delivery, encapsulating magnetic nanostructures (MNS) (Fig 1b) into PEG-bl-PPS nanocarriers is of interest4. Loading of MNS would provide responsiveness to both 1) static and 2) alternating magnetic fields, allowing for 1) controlled directional manipulation of nanocarriers and 2) hyperthermia-based treatment and actuated drug release5. MNS have also been well established for diagnostic imaging, as they are potent T2 MRI contrast agents4. Here, we have loaded MNS into three different PEG-bl-PPS morphologies and characterized the resulting effects on MR imaging parameters as a first step in developing a magnetic PEG-bl-PPS construct for drug delivery.