An efficient tumor-inducible nanotheranostics for magnetic resonance imaging and enhanced photodynamic therapy

Though imaging guided photodynamic therapy (PDT) has emerged as a promising cancer therapy, how to enhance the PDT efficiency is still a research hotpot due to the tumor hypoxia and insufficient dosage of photosensitizers in the tumor site. Herein, a multifunctional theranostic nanoplatform was rationally constructed by nanoscale metal organic frameworks (NMOFs), bovine serum albumin (BSA), sulfadiazines (SDs), and MnO2. Porphyrin as organic ligands involved in the formation of NMOFs, which could allow more photosensitizers in one system. BSA as ideal carrier endows the nanoplatform with low toxicity and long circulation. SDs was introduced to provide actively targeting for the over-expressed carbonic anhydrase LX (CA IX) in tumor cells. More importantly, this nanoplatform can overcome the hypoxic microenvironment via down-regulating CA IX and catalyzing H2O2 to generate O-2, resulting in significantly enhanced PDT effect, which was demonstrated by the photocytotoxicity against 4T1 cells and the decreased tumor volume. In addition, in vitro/vivo T-1-weighted MRI results showed that the nanoplatform could be served as positive MRI contrast agent with a higher longitudinal relaxivity value (r(1)) at 6.09 mM(-1) s(-1) than that of clinical clinical contrast agent (Gd-DTPA, r(1) = 4.33 mM(-1) s(-1)). Such theranostic nanoplatform integrates multifunctional contents into one system and thereby provides a new strategy for targeted tumor therapy.