Fluctuation-resilient ratiometric SERS enabled by programmable aptamer disassembly for pump-free microfluidic AKI detection

Acute kidney injury (AKI) requires rapid and reliable biomarker quantification, yet early assessment is hindered by delayed biomarker kinetics and signal fluctuation under decentralized testing conditions. Here, we developed a pump-free microfluidic aptamer-ratiometric surface-enhanced Raman scattering (SERS) platform for simultaneous quantification of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (Cys C). The assay uses a Y-shaped aptamer architecture to convert target binding into programmed structural disassembly and controlled release of Au@Ag SERS tags. A substrate-embedded internal standard enables self-calibrated readout through the I 1617 /I 2228 ratio, thereby improving signal robustness against substrate heterogeneity and environmental interference. Integrated into a capillary-driven microfluidic chip, the platform completed dual-biomarker analysis within 15 min. It achieved detection limits of 1 pg/mL for NGAL and 34 pg/mL for Cys C, with excellent linearity (R 2 > 0.99). In a cisplatin-induced AKI rat model, both biomarkers increased significantly at 4-6 h after injury, preceding oxidative stress imaging and histopathological changes. Analysis of clinical serum samples showed good agreement with enzyme-linked immunosorbent assay and recovery rates above 99%. These results demonstrate a rapid and reliable strategy for early AKI assessment and quantitative point-of-care biomarker analysis.

急性肾损伤（AKI）需要快速可靠的生物标志物定量，但分散测试条件下生物标志物动力学延迟和信号波动阻碍了早期评估。在这里，我们开发了一种无泵微流体适体比例表面增强拉曼散射 (SERS) 平台，用于同时定量中性粒细胞明胶酶相关脂质运载蛋白 (NGAL) 和半胱氨酸蛋白酶抑制剂 C (Cys C)。该检测使用 Y 形适体结构将靶标结合转化为程序化的结构分解和 Au@Ag SERS 标签的受控释放。基质嵌入的内标可通过 I 1617 /I 2228 比率实现自校准读数，从而提高针对基质异质性和环境干扰的信号鲁棒性。该平台集成到毛细管驱动的微流控芯片中，在 15 分钟内完成双生物标志物分析。 NGAL 的检测限为 1 pg/mL，Cys C 的检测限为 34 pg/mL，并且具有出色的线性度 (R 2 > 0.99)。在顺铂诱导的 AKI 大鼠模型中，两种生物标志物在损伤后 4-6 小时、氧化应激成像和组织病理学变化之前显着增加。临床血清样本分析与酶联免疫吸附测定结果吻合良好，回收率高于99%。这些结果证明了早期 AKI 评估和定量护理点生物标志物分析的快速可靠策略。