ARMOR: Auto‐Assembled Resilient Biomimetic Calcified Ornaments for Selective Cell Protection by Dual‐Aptamer‐Driven Hybridization Chain Reaction

Abstract Unlike plant and microbial cells having cell walls, the outermost layer of mammalian cell is a delicate, two‐layered structure of phospholipids with proteins embedded, which is susceptible to environmental changes. It is necessary to create an “armor” on cell surface to protect cell integrity. Here, we propose an A uto‐assembled R esilient bio M imetic calcified OR naments (ARMOR) strategy driven by dual‐aptamer‐based hybridization chain reaction (HCR) and Ca 2+ assisted calcification for selective cell protection. This co‐recognition design enhances the selectivity and leverages robust in situ signal amplification by HCR to improve the sensitivity. The calcified shell is cogenerated by crosslinking the alginate‐HCR product with Ca 2+ ion. ARMOR has high efficiency for shielding cells from environmental assaults, which can be applied to circulating tumor cell (CTC) protection, isolation, and identification, maintaining the native state and intact genetic information for downstream analysis.