Colorimetric detection of citric acid as the biomarker for urolithiasis based on sodium dodecylsulfate-AgNPs with a portable CD-spectrometer

Citric acid (CA) has been considered as a biomarker of urolithiasis due to its vital suppression role in urinary stone formation. Most analytical methods for detecting CA are complicated and require expensive equipment. Herein, a colorimetric method based on sodium dodecylsulfate (SDS) modified AgNPs was presented for convenient and portable detection of CA in urine. By detecting the absorption of the solution color, the quantitative detection of CA can be achieved. The pH value of SDS-AgNPs, concentration of Al3+ and incubation time were optimized. Under optimal conditions, the method has the detection range of 1-10 mg/L, with a limit of detection (LOD) of 0.21 mg/L. Moreover, a self-developed portable CD(Compact Disk)-spectrometer (CDs) was established for detecting CA with a LOD of 0.49 mg/L featuring high simplicity, low time cost and good portability. This method was also validated with good selectivity to CA. In addition, the artificial urine samples were also detected to verify the capability of the method and CDs. The results validated that the method integrating with the CDs can be a promising platform for citric acid detection that can be further used for early screening and prognostic monitoring of urolithiasis. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A simple and portable method for citric acid detection was proposed in this study, utilizing SDS-modified AgNPs for colorimetric quantification of CA. The self-developed CD-spectrometer showed high simplicity, low time cost, and good portability, with good selectivity and sensitivity to CA detection. The method integrated with CDs can be a promising platform for early screening and prognostic monitoring of urolithiasis.