Long in vivo circulating nanomicelles formed by sharp-contrast Janus star polymers derived from β-cyclodextrin grafted with lipids and polyzwitterions

Amphiphilic block polymers have the ability to self-assemble and form nanomicelles, which have been extensively studied as nanocarriers for improving the bioavailability and biodistribution of chemotherapeutic drugs while reducing systemic toxicity. However, polymer micelles often face issues with poor stability in the bloodstream, leading to a short circulation time and leakage of the payload. Here, this work reports a rational design of a sharp-contrast Janus star polymer (SJSP) consisting of multiple arms of superhydrophobic lipid moieties and superhydrophilic polyzwitterion chains attached to a β-cyclodextrin core. The SJSP polymer forms nanomicelles possessing a stable core and a controllable and dense stealth shell that effectively protects them in the bloodstream, preventing payload leakage and blood protein adsorption. It is demonstrated that the hydrophobic/hydrophilic balance can be optimized to achieve strong micellar assembly by adjusting the number of lipid and polyzwitterion arms. The SJSP micelle system shows significantly longer blood circulation time in vivo compared to linear counterparts and other available amphiphilic block copolymer micelle systems. Therefore, the SJSP micelle design offers a promising strategy for developing nanocarriers with potential for translational applications in vivo.