Dariush Saberi

A highly selective and sensitive colorimetric sensor for the determination of naproxen (NAP) based on the aggregation of the thiolated ?-cyclodextrin (T?-CD) functionalized gold nanoparticles (T?-CD-Au NPs) in the presence of NAP and Zn2 is described. The hydrophobic end of NAP interacts with the immobilized T?-CD on the Au NPs and forms the complex of T?-CD:NAP while the Zn2 ions form a 1:2 complex of (NAP)2Zn with the carboxyl groups of NAP resulting in the aggregation of functionalized gold nanoparticles. As a result of aggregation, the localized surface plasmon resonance (LSPR) band of functionalized gold nanoparticles around 520 nm decreases and a new red shifted band at 650 nm appears which increases gradually as the function of NAP concentration. The calibration graph derived from the intensity ratios of absorbance at 650 nm to 520 nm was linear in the concentration range of 4–180 ?g L?1of NAP. At the optimum conditions, the limit of detection (LOD) and quantification (LOQ) were found to be 0.6 and 2.1 ?g L?1, respectively and the relative standard deviation at 20 ?g L?1of NAP (n=5)was 2.5%. The selectivity and applicability of themethod was verified through analyzes of the synthetic samples containing the major interference compounds reported in literature as well as tablets, wastewater and urine samples. The accuracy of the method was evaluated by recovery experiments and analysis of pharmaceutical tablets.