A Self‐Disguised Nanospy for Improving Drug Delivery Efficiency via Decreasing Drug Protonation

Abstract Nanoscale drug carriers play a crucial role in reducing side effects of chemotherapy drugs. However, the mononuclear phagocyte system (MPS) and the drug protonation after nanoparticles (NPs) burst release still limit the drug delivery efficiency. In this work, a self‐disguised Nanospy is designed to overcome this problem. The Nanospy is composed of: i) poly (lactic‐co‐glycolic acid)‐polyethylene glycol (PLGA‐PEG) loading doxorubicin is the core structure of the Nanospy. ii) CD47 mimic peptides (CD47p) is linked to NPs which conveyed the “don't eat me” signal. iii) 4‐(2‐aminoethyl) benzenesulfonamide (AEBS) as the inhibitor of Carbonic anhydrase IX (CAIX) linked to NPs. Briefly, when the Nanospy circulates in the bloodstream, CD47p binds to the regulatory protein α (SIRPα) on the surface of macrophages, which causes the Nanospy escapes from phagocytosis. Subsequently, the Nanospy enriches in tumor and the AEBS reverses the acidic microenvironment of tumor. Due to above characteristics, the Nanospy reduces liver macrophage phagocytosis by 25% and increases tumor in situ DOX concentration by 56% compared to PLGA@DOX treatment. In addition, the Nanospy effectively inhibits tumor growth with a 63% volume reduction. This work presents a unique design to evade the capture of MPS and overcomes the influence of acidic tumor microenvironment (TME) on weakly alkaline drugs.