Background‐Free Near‐Infrared II Photothermal Lateral Flow Immunoassay for Precise Point‐of‐Care Diagnosis of Heart Failure

Heart failure (HF) represents a major global health burden characterized by high mortality and frequent rehospitalization. The deployment of point‐of‐care diagnostics for HF management is largely hampered by the lack of portable, highly sensitive, and quantitative tools. Herein, we report a near‐infrared II (NIR‐II) photothermal lateral flow assay (PT‐LFA) biosensor for the rapid diagnosis and risk stratification of HF. By employing NIR‐II PT probes with exceptional plasmonic photothermal performance, this platform effectively suppresses background thermal interference originating from the nitrocellulose membrane and non‐specifically adsorbed biological substances. This background‐free NIR‐II PT‐LFA biosensor achieves a wide dynamic range of 20–1000 ng/mL and a limit of detection of 5.6 ng/mL for soluble suppression of tumorigenicity‐2 (sST2) detection, significantly outperforming both conventional colorimetric readout and standard ELISA. Clinical validation demonstrates that this biosensor distinguishes HF patients with 98.0% accuracy, 100% sensitivity, and 94.4% specificity. Notably, by directly targeting sST2, this approach provides superior diagnostic performance compared to standard NT‐proBNP‐based clinical protocols, which are often confounded by age and body mass index. This work establishes a novel NIR‐II photothermal strategy that significantly enhances the diagnostic performance of PT‐LFA platforms, offering a robust and practical platform for HF management in clinical and point‐of‐care settings.