Rebirth of Aspirin Synthesis By‐Product: Prickly Poly(salicylic acid) Nanoparticles as Self‐Anticancer Drug Carrier

Abstract As a great drug, aspirin has been used to treat many important diseases. To expand the biomedical applications of the aspirin material family, in this report, the authors polymerized salicylic acid (functional part of aspirin) into poly (salicylic acid) (PSA), which was once a by‐product during aspirin synthesis. PSA can be formulated into sub‐100 nm prickly nanoparticles (NPs) via a nanoprecipitation self‐assembly procedure. The PSA NPs are found to be nontoxic to normal cells and cancer cells, but can inhibit tumor growth in the CT26 mouse model. The anticancer drug can be effectively loaded into PSA NPs and the drug‐loaded PSA NPs show ultra‐high blood vessel penetration, tumor penetration, and tumor accumulation due to the special prickly nanostructure. With these combined advantages, including the self‐therapeutic effects, high biosafety, and high tumor accumulation performance, drug‐loaded PSA NPs achieved a significant tumor inhibition efficacy without causing any side effects. Therefore, a new poly (salicylic acid) NP platform is successfully developed from a byproduct of aspirin synthesis, expanding the biomedical applications of aspirin‐related materials.