Selective modulation of ligand–receptor interaction is essential in targeted therapy. In this study, we design an intelligent “scan and unlock” DNA automaton (SUDA) system to equip a native protein‐ligand with cell‐identity recognition and receptor‐mediated signaling in a cell‐type‐specific manner. Using embedded DNA‐based chemical reaction networks (CRNs) on the cell surface, SUDA scans and evaluates molecular profiles of cell‐surface proteins via Boolean logic circuits. Therefore, it achieves cell‐specific signal modulation by quickly unlocking the protein‐ligand in proximity to the target cell‐surface to activate its cognate receptor. As a proof of concept, we non‐genetically engineered hepatic growth factor (HGF) with distinct logic SUDAs to elicit target cell‐specific HGF signaling and wound healing behaviors in multiple heterogeneous cell types. Furthermore, the versatility of the SUDA strategy was shown by engineering tumor necrotic factor‐α (TNFα) to induce programmed cell death of target cell subpopulations through cell‐specific modulation of TNFR1 signaling.

A click-type protein–DNA conjugation, named as MnDDC (Mn2+-activated DCV-DNA conjunction), is presented, where DCV (rep protein of duck circovirus) and its target DNA work as the modular blocks to rapidly and effectively generate Mn2+-dependent and site-specific protein–DNA linkage. On the basis of MnDCC, a fluorescent Mn2+ biosensor composed of DCV and a molecular beacon, was developed for rapid sensing of Mn2+ within 2 min with nanomolar sensitivity. Using the proposed biosensor, not only analysis of Mn2+ in real samples (e.g., serum and food), but also wash-free fluorescent imaging of Mn2+ in extracellular environment and cytoplasm have been achieved. Moreover, the MnDDC-based sensor was proved to be a powerful tool for visualization of Mn2+ during exploration of the associated cytotoxicity in living neural cells, which is helpful to reveal the cellular responses toward the disordered homeostasis of Mn2+ in both extracellular and intracellular microenvironments.

For the analysis of biological analytes in complex matrices, it is difficult to achieve extraction of analytes and enrichment in an aqueous−aqueous single-drop microextraction system. In this study, we proposed a pH-dependent polydopamine (PDA)-coated vesicle/Fe 3 O 4 magnetic aqueous−aqueous in a single-drop microreactor (SDMR) for the direct fluorescence detection of glutathione S-transferase (GST), a metabolic enzyme involved with crucial biological processes, in biological samples. After extracting and enriching the GST target from an aqueous−aqueous single-drop interface, the extraction process was conducted rapidly in 6 s in the SDMR system. The GST was first extracted from the sample solution via the GST-Aptamer on the polydopamine-coated vesicle/ Fe 3 O 4 nanospheres (Fe 3 O 4 @PDA@GST-Aptamer). Then, as the pH changed from weakly acidic to weakly alkaline in the SDMR system, the GST and GST-Aptamer were released from Fe 3 O 4 @PDA@GST-Aptamer nanospheres and captured by polydiacetylene vesicles via the capture probe. These changes altered the effective conjugation length and angle of the vesicle trunk, generating a highly enhanced fluorescence signal. This not only achieved the purpose of target enrichment but also reduced interferences posed by matrix effects. The approach can be used for the direct detection of GST in genuine urine and blood without any sample pretreatment. The linear range was 0.005 to 0.5 μg/mL, and the limit of detection was 0.834 ng/mL. The recoveries of GST in genuine blood samples ranged from 90.8 to 108.0% and in urine from 91.6 to 102.8%. The method has the capability of handling complex samples directly by enabling microextraction in an aqueous−aqueous single-drop system.

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