Polydopamine-based quantitation of albuminuria for the assessment of kidney damage

Proteinuria is considered indicative of kidney damage that can be related to various adverse outcomes. Nowadays, there is a huge demand for routine urine screening methods to assess health risks in clinical setting without expensive procedures and long pretreatment of the sample. To address this issue, a polydopamine-based colorimetric assay to determine urinary albumin concentration in real samples is proposed here. The core of this approach relies on the established competitive adsorption of polydopamine film and human serum albumin onto the polystyrene surface of ELISA plates. Herein, we investigated the influence of temperature and the Tris-HCl buffer concentration on the polydopamine film growth. The absorbance of polydopamine film, after 24 h at 25 °C, decreases with the increase of HSA concentration, allowing the selective detection of HSA down to 0.036 ± 0.001 g L^-1 in untreated urine. This simple and low-cost bioanalytical assay exhibited very good reproducibility, %CV_mean = 2 in human urine, and was superior in terms of analytical performances to some standard methods available on the market, especially in comparison to the Bradford assay, for early screening and assessment of kidney damage.