One-Step, Lateral-Flow Quantification of Human Urine Albumin Using an In Situ Minipump and Clinical Evaluation in Renal Patients

The development of sensors for the detection of albumin concentrations in urine is essential for the long-term detection and treatment of kidney disease. Albumin is an important biomarker for kidney diseases. However, albumin concentrations in patient’s urine are often too high (more than 0.15 mg/mL), causing competitive lateral flow immunoassays (LFIAs) to exceed detection ranges. In this work, we report for the first time a one-step, fluorescent lateral-flow quantification of human urine albumin using an in situ minipump and clinical evaluation in renal patients, eliminating the need for external sample dilution. The device is constructed by integrating a LFIA strip and an in situ minipump that sits above the sample/conjugate pad of the strip. The detection is based on competitive immunoassay by using fluorescent nanoparticles as the probe, and the in situ pump performs on-chip dilution. The linear detection range with this device is 0.1–10 mg/mL for a 1000-fold dilution of the sample with the pump, and 1–100 mg/mL for a 10000-fold dilution. The device can be used for the direct quantification of albumin in the urine of patients with clinical kidney disease. We anticipate that the work can open up exciting new opportunities for the quantification of protein biomarkers, and their wide range of applications in clinical and home-settings.