Multiplexed plasmon-enhanced lateral flow assay for early diagnosis of acute kidney injury

Early diagnosis of acute kidney injury (AKI) remains a major clinical challenge due to the delayed and insensitive nature of conventional markers such as serum creatinine. Urinary protein biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (CysC), provide earlier and complementary information on kidney injury, but their clinical translation is limited by the lack of rapid, quantitative, and multiplexed point-of-care (POC) diagnostic tests. Here, we report a multiplexed plasmonic-fluor-based lateral flow assay (p-LFA) that enables sensitive, quantitative, and simultaneous detection of NGAL and CysC. By harnessing ultrabright plasmonic-fluor nanolabels and ratiometric fluorescence analysis, the p-LFA achieves picogram-per-milliliter analytical sensitivity comparable to that of the enzyme-linked immunosorbent assay (ELISA). In addition, the simplified assay format enables sample-to-answer times as short as 10 min, while maintaining sensitivity sufficient for accurate AKI detection. Clinical validation using pediatric urine samples demonstrates a strong correlation with ELISA measurements for both biomarkers. Combined analysis of NGAL and CysC significantly improves AKI diagnostic performance, yielding an area under the receiver operating characteristic curve of 0.973 with a clinical sensitivity of 90.9% and specificity of 91.2% in the studied cohort. Furthermore, a low-cost, portable fluorescence reader enables quantitative performance equivalent to benchtop imaging while dramatically reducing instrument cost and complexity. Collectively, this work establishes a scalable and adaptable p-LFA platform that bridges laboratory-grade immunoassays and practical POC diagnostics, offering a promising solution for early AKI detection and multiplexed biomarker analysis in decentralized healthcare settings.