A Cell‐Resolved Ultrastable Biosensor Enables One‐Step Detection of Gene‐Fusion Transcripts in Unprocessed Whole Blood

ABSTRACT Cell‐specific detection of aberrant mRNA in blood is essential for diagnosing and treating hematological malignancies. However, current sensors are unable to function in unprocessed whole blood due to limitations in chemical stability and cell‐targeting capability. Here, we engineer a cell‐resolved ultrastable sensor for hematology (CRUSH) via spherical‐nucleic‐acid (SNA) technology, which enables live‐cell detection of leukemia fusion transcripts in unprocessed whole blood. CRUSH employs stoichiometrically controlled thiol protector to achieve a defect‐free thiol monolayer on AuNPs. This design feature endows CRUSH with a record‐breaking stability, withstanding 0.1 M dithiothreitol, a 10,000‐fold improvement over conventional SNAs. We also demonstrate that the phagocytic bias of myeloid cells over lymphoid cells drives selective internalization of CRUSH in myeloid lineages in whole blood. Leveraging cellular selectivity and engineered stability, CRUSH offers a mixed‐and‐read diagnostic test, where lyophilized sensors are directly mixed with whole blood samples, followed by standard flow cytometry analysis. This one‐step test detects BCR‐ABL1 fusions in living myeloid cells with high specificity and robustness, enabling accurate discrimination of multilineage acute lymphoblastic leukemia within 1 h. Our study bridges biosensing innovation with urgent diagnostic needs, offering a rapid, specific, and robust tool for accurate diagnosis and treatment of hematologic malignancies.