Engineering Poly(ethylene glycol) Nanoparticles for Accelerated Blood Clearance Inhibition and Targeted Drug Delivery

Surface modification with poly(ethylene glycol) (PEGylation) is an effective strategy to improve the colloidal stability of nanoparticles (NPs) and is often used to minimize cellular uptake and clearance of NPs by the immune system. However, PEGylation can also trigger the accelerated blood clearance (ABC) phenomenon, which is known to reduce the circulation time of PEGylated NPs. Herein, we report the engineering of stealth PEG NPs that can avoid the ABC phenomenon and, when modified with hyaluronic acid (HA), show specific cancer cell targeting and drug delivery. PEG NPs cross-linked with disulfide bonds are prepared by using zeolitic imidazolate framework-8 NPs as templates. The reported templating strategy enables the simultaneous removal of the template and formation of PEG NPs under mild conditions (pH 5.5 buffer). Compared to PEGylated liposomes, PEG NPs avoid the secretion of anti-PEG antibodies and the presence of anti-PEG IgM and IgG did not significantly accelerate the blood clearance of PEG NPs, indicating the inhibition of the ABC effect for the PEG NPs. Functionalization of the PEG NPs with HA affords PEG NPs that retain their stealth properties against macrophages, target CD44-expressed cancer cells and, when loaded with the anticancer drug doxorubicin, effectively inhibit tumor growth. The innovation of this study lies in the engineering of PEG NPs that can circumvent the ABC phenomenon and that can be functionalized for the improved and targeted delivery of drugs.