A colorimetric detection of creatinine based-on EDTA capped-gold nanoparticles (EDTA-AuNPs): Digital Image Colorimetry

A colorimetric sensor based on EDTA-modified gold nanoparticles (EDTA-AuNPs) has been developed for the sensitive and selective detection of creatinine using UV–vis spectrophotometer and digital image method. The presence of creatinine in EDTA-AuNPs results in a decrease in the absorbance peak at 524 nm and the appearance of an absorbance peak at 700 nm in the UV–vis spectrum. Creatinine induces the aggregation of EDTA-AuNPs, resulting in a color change from wine red to blue, which is easily observable with the naked eye. Color changes in colloids of EDTA-AuNPs can be further developed using digital image methods based on red, green, and blue colors to detect creatinine. The UV–vis spectrophotometer method demonstrated a linear relationship between the absorbance ratio at A₇₀₀/A₅₂₄ nm in the range of 0.0–5.0 mM, with a regression coefficient of 0.9906 and a detection limit of 0.125 mM. Meanwhile, the digital image method demonstrates a linear relationship between red color intensity (R) and creatinine concentration, with a high regression coefficient of 0.996 and a low detection limit of 0.050 mM. Creatinine testing conducted on artificial urine samples demonstrated a recovery rate between 97.5 % and 101.7 %, with a relative standard deviation (RSD) ranging from 0.28 % to 0.74 %. These results indicate good measurement accuracy and precision for the creatinine testing method.