Rapid urinary albumin detection using a simple redox cycling process coupled with a paper-based device

Abstract

A novel electrochemical-chemical (EC) redox cycling process was proposed for the sensitive, simple, and rapid detection of urinary albumin. This system employs a unique detection scheme based on the combination of ferricyanide ([Fe(CN)6]3−) and methylene blue (MB) for signal amplification without the need for any electrode surface modifications. Measurements of bovine serum albumin (BSA) were performed as proof of concept using disposable electrochemical paper-based analytical devices (ePADs) as detection platforms. The quantification of albumin is accomplished by using an indirect detection strategy. In the absence of BSA, electron transfer via EC redox cycling process occurs readily between the redox species and the electrode surface, resulting in a large electrochemical signal. The redox species solution containing BSA, on the other hand, provides a low signal current due to the hindrance of BSA on the electrode surface, which impedes the electron transfer of the proposed redox probe. Under the optimized conditions, the linear range was 1–500 mg dL−1 with a detection limit of 0.072 mg dL−1. This finding leads to the development of a powerful method for the direct detection of albumin at a low concentration and no requirement for correction by creatinine. The proposed devices were successfully used to detect albumin in real urine samples with satisfactory results, demonstrating good agreement with the standard method and the reliability. Aside from the ease and rapidity, the proposed method is inexpensive, sensitive, and a promising tool for clinical diagnosis of chronic kidney disease and suitable for point-of-care testing in developing countries. © 2022 Elsevier B.V.