A Highly Sensitive\nLateral-Flow Strip Using Latex\nMicrospheres to Detect NGAL in Urine Samples

The incidence of kidney disease is increasing worldwide.\nRapid\nand cost-effective approaches for early detection help prevent this\ndisease. Neutrophil gelatinase-associated lipocalin protein (NGAL)\nis a novel biomarker for acute kidney injury (AKI) and chronic kidney\ndisease (CKD). We aimed to develop a lateral flow strip (LFS) based\non a lateral flow immunoassay method (LFIA), using latex microspheres\n(LMs) as a color labeling to detect NGAL in urine. The performance\nand potential of the developed LMs-LFS at a point-of-care (POC) testing\nwere evaluated. The results showed that LMs-LFS successfully detected\nurinary NGAL within 15 min with high specificity without cross-reactivity\nto or interference from other endogenous substances in urine. The\nvisual limit of detection (vLOD) was 18.75 ng/mL, and the limit of\ndetection (LOD) was 1.65 ng/mL under the optimum condition. The LMs-LFS\ndeveloped in this study showed a high correlation with the enzyme-linked\nimmunosorbent assay (ELISA) method (<i>R</i><sup>2</sup> = 0.973, <i>n</i> = 60 urine specimens) for detecting\nNGAL in urine. The LMs-LFS remained stable for at least six months\nat room temperature. The LMs-LFS can be a rapid, sensitive, and specific\ntool for the diagnosis and follow-up of renal disorders at the POC.