Dual‐Space Confined Magnetic Single‐Atom Nanozyme for Intelligent Point‐of‐Care Diagnostics

ABSTRACT Colorimetric immunochromatographic biosensors (ICBs) are widely deployed in point‐of‐care testing (POCT). However, their application is fundamentally restricted by the limited detection sensitivity, which impedes reliable early disease diagnosis. Herein, we develop a high‐performance magnetic single‐atom nanozyme (mFeSiO 2 @PtSAN) through a dual‐space confinement strategy. This strategy, utilizing low‐temperature photochemical reduction instead of the traditional pyrolysis method, concurrently guarantees atomic dispersion, superparamagnetism, and a Pt‐N 4 Cl 2 coordination with a high Pt loading of 6.0 wt.%. The mFeSiO 2 @PtSAN shows outstanding oxidase‐like activity, as evidenced by a low Michaelis constant ( K m = 0.068 m M ) and a high maximal reaction velocity ( V max = 4.67 × 10 −7 M s −1 ). When incorporated into an ICB platform for cardiac troponin I detection, the mFeSiO 2 @PtSAN allows for visual detection at 0.01 ng/mL and attains a limit of detection of 3.3 pg/mL after catalytic amplification, which represents a 26.9‐fold improvement compared to conventional Pt nanoparticle‐based probes. Moreover, the combination with a convolutional neural network‐based image analysis system achieves a 94.7% accuracy for clinical samples. This research not only offers a scalable model for the design of magnetic single‐atom nanozymes but also presents a synergistic approach toward intelligent, high‐performance POCT by integrating advanced nanozymes with artificial intelligence‐driven analytics.