Colorimetric Determination of Urinary Creatinine in Proteinuria Patients by Chromaticity Analysis of Gold Nanoparticle Colloidal Solutions

Several scientific works have reported the use of colloidal gold nanoparticle (AuNP) solutions as a colorimetric probe for creatinine detection. Nonetheless, urinary protein is one of the primary chemical components that can interfere with creatinine detection. In this work, we developed a colorimetric probe using AuNP colloidal solution to detect creatinine in the urine of proteinuria patients. A microchamber array was prepared to minimize the sample volume and was used to simultaneously perform spectral recording and image acquisition of several samples. The analyzed volume for each sample was 15 mu L. A camera coupled with liquid crystal tunable filters was used to record hyperspectral images, and the signals were then converted to localized surface plasmon resonance (LSPR) spectra. Color changes in the AuNP colloidal solution in the presence of varying concentrations of creatinine and human serum albumin (HSA) indicated different features and could be detected by a hyperspectral imaging technique. The relevant concentration ranges of creatinine and HSA were 5 - 200 and 50 - 250 mg dL(-1), respectively. Furthermore, a smartphone camera was adopted to record a color mapping image of the AuNP colloidal solution in the presence of creatinine and HSA at these concentration ranges. Contour plots of red and blue chromaticity levels from color mappings were produced, and 2D fitting equations obtained from these contour plots were adopted to determine the creatinine concentration in the urine of proteinuria patients. This practical technique can be used for screening and can be further developed as a household biosensing device for urinalysis.