Tube-Anchored Dual-Atom Nanozyme Hydrogel Microreactors with Dual-Interface Engineering for Portable Biosensing

DNA hydrogels are promising platforms for portable biosensing, but their combination with high-activity catalytic nanomaterials remains hindered by interfacial incompatibility and inconsistent device-level retention. Here, a tube-anchored hydrogel microreactor is developed, coupling Co-Ni dual-atom nanozymes (CoNi DANs), interfacial stabilization, and CRISPR-triggered release within a standard centrifuge tube. CoNi DANs are synthesized on a defect-rich nitrogen-doped carbon scaffold, achieving high metal loading and improved peroxidase-like activity relative to those of their single-atom counterparts. Carboxymethyl cellulose-mediated interfacial stabilization then suppresses CoNi DAN aggregation through electrostatic complementarity and polymeric steric shielding, enabling uniform dispersion of CoNi DANs within the DNA hydrogel. A polydopamine-based dual-anchoring strategy further combines covalent grafting with sequence-specific DNA hybridization, providing a chemically reinforced hydrogel-device interface. Upon target recognition, CRISPR/Cas12a trans-cleavage activity induces controlled hydrogel degradation and on-demand release of CoNi DANs for colorimetric and electrochemical dual-mode readout. Using atrazine as a proof-of-concept analyte, the platform achieves limits of detection of 6.1 and 2.1 pg mL-1 for colorimetric and electrochemical modes, respectively, with satisfactory recoveries in real samples. A smartphone-assisted digital readout module further improves the portability of the colorimetric mode. The dual-interface design, uniting material-level compatibilization with device-level dual-anchoring, provides a generalizable framework for embedding high-activity nanozymes into responsive DNA hydrogel microreactors for portable on-site biosensing.