All-in-one theranostic nanoplatfbrm with controlled drug release and activated MRI tracking functions for synergistic NIR-II hyperthermiachemotherapyof tumors

Real-time tracking drug release behavior is fundamentally important for avoiding adverse effects or unsuccessful treatment in personalizemedical treatment.However,the development of a non-invasive drug reporting platform still remains challenging.Herein the design of a novelsyn thetic magnetic resonance imaging(MRI)agent for drug release tracking(SMART)is reported,which integrates photothermal core andparamagnetic ion/drug loading shell with a thermal valve in a hybrid structure.Through near-infrared(NIR)-II photothermal effect originatingfrom inner Au-Cu9S5 nanohybrid core,burst release of drugs loaded in the mesoporous silica shell is achieved.The concomitant use of aphase change material not only prevents premature drug release,but also regulates heating effect,keeping local temperature below 45℃,enabling synergistic chemotherapy and mild hyperthermia in vitro and in vivo.Furthermore,the drug release from SMART facilitates protonaccessibility to the paramagnetic ions anchored inside mesopores channels,enhancing Iongitudinal T1 relaxation rate and displaying positivesignal correlation to the amount of released drug,thus allowing norvinvasive real-time monitoring of drug release event.The current studyhighlights the potential of designed MRI nanophores such as SMART for real-time and in-situ monitoring of drug delivery for precisionthera nostic applications.