Colorimetric sensor for cimetidine detection in human urine based on d-xylose protected gold nanoparticles.

Herein, a simple, novel, and rapid colorimetric sensor for cimetidine (Cim) detection based on d-xylose protected gold nanoparticles (d-x@AuNPs) has been developed for the first time. The d-x@AuNPs were characterized by UV-vis, TEM and FT-IR techniques. Cimetidine causes the aggregation of d-x@AuNPs due to the formation of a strong covalent Au-N bond and electrostatic binding. As the cimetidine concentration increased, the color of the solutions gradually changed from wine-red to blue, and the large absorption band shifted from 533 to 680 nm upon d-x@AuNP aggregation. The effects of different experimental parameters were investigated. A comparative study on the detection of Cim using citrated capped AuNPs and d-x@AuNPs was presented. Under optimum conditions, the UV-vis spectra showed that the absorption ratio (A680/A533) increased linearly with the concentration of cimetidine in the range of 7 × 10-8 to 3 × 10-6 M with a correlation coefficient of 0.9956 and a limit of detection of 1 × 10-8 M without needing any complicated instruments. The selectivity of the d-x@AuNP detection system for cimetidine was excellent when compared with other ions and analytes. Due to their rapid and visible color changes, and their remarkable selectivity, the d-x@AuNPs synthesized in this study were suitable and could be applied to the detection of cimetidine in human urine.