Abstract: The present disclosure provides stimuli-responsive particles, methods of preparing stimuli-responsive particles, and methods of using the stimuli-response particles. Unlike conventional platforms, (e.g., polymers, liposomes, dendrimers) the particles of the present disclosure have precise size control of the particle diameter, high uniformity, high stability, high active agent uptake capacity, minimal premature active agent leakage, biocompatibility, and biodegradability. Additionally, the present disclosure provides magnetic resonance imaging (MRI) systems and methods of using the MRI systems in combination with the stimuli-responsive particles described herein.