Topical cationic hairy particles targeting cell free DNA in dermis enhance treatment of psoriasis.

Abnormal high level of cell free DNA (cfDNA) triggers chronic inflammation to exacerbate psoriasis symptoms. Scavenging cfDNA by topical cationic polymeric nanoparticles has been certified as an effective therapeutic strategy for treating psoriasis. However, cationic cfDNA scavengers have a great potential risk to organs after entering systemic circulation through skin barrier. For better transformation to clinical application, herein a series of poly(2-(dimethylamino)ethyl methacrylate) (PDMA) grafted hairy silica particles (cSPs) with tunable PDMA length and particle size are applied to scavenge cfDNA in dermis. We reveal that the structure of cSPs correlates with the permeation ability across stratum corneum, retention time in dermis, binding affinity to cfDNA, and toxicity tolerance, which in turn affect the therapeutic effect. Especially, the cSPs of 700 nm show more accumulation and longer retention in psoriatic lesions, leading to excellent treatment results. They also outperform the cSPs of 200 nm at a lower administration frequency. Thus, we address the issues of size, cationic content of cSPs to open a potential new avenue to topically treatment of psoriasis by targeting cfDNA in dermis.