Synthesis of Sodium Citrate-Capped Gold Nanoparticles and its Application for Creatinine Detection in Urine Sample by Colorimetric Analysis Based on the Red-Green-Blue (RGB) Digital Image

Abstract

AuNPs have been synthesized with reducing agents and sodium citrate covering agents using the colorimetric method. The formation of sodium citrate-covered AuNPs was confirmed using a UV-Vis spectrophotometer. The optimization of creatinine concentration of 10 mM was indicated by shifting the absorption peak from 530 to 700 nm. The results of this optimization were then used to standardize the detection of creatinine in urine samples using a validation test method. The TEM results showed that the AuNPs were dispersed at relatively large distances. The size of the AuNPs was 30.67 nm and creatinine was 19.96 nm. This is because no substance had aggregate NPS, therefore, the particles are still scattered. Testing the quantitative value of Red-Green-Blue (RGB) digital images involved a mobile phone camera. The resulting images were stored in a memory card and then transferred to a laptop/computer. The data were processed using ImageJ software. The linear correlation and selectivity of the quantitative values ​​of Red-Green-Blue (RGB) from the RGB method were compared with the results of colorimetric detection using the UV-Vis spectrophotometric method. The data were used to determine the amount of creatinine concentration. The results exhibited that sodium citrate had the ability as a reducing agent and a covering agent in the synthesis of AuNPs for the determination of creatinine. The RGB digital image method had good sensitivity to creatinine with LoD of 0.068 mM dan LoQ of 0.228 mM, which was smaller than the UV-Vis spectrophotometric method where LoD was 0.225 mM and LoQ was 0.751 mM. The validation method results showed that AuNPs can be used as a creatinine sensor. This method used a colorimetric sensor of the Red-Green-Blue (RGB) component in urine samples and was translated with ImageJ software.