Cu2+-induced quenching and recovery of the luminescence of dopamine-conjugated carbon dots for sensing deferasirox in plasma

Abstract

A novel dopamine-conjugated carbon dots (DA-CDs) sensor has been designed for estimation of deferasirox (DFX) in plasma of β-thalassemia. The carbon dots (CDs) were synthesized by using citric acid and urea as precursors and heated in the microwave. Then, the CDs was further conjugated with dopamine to obtain the final product, DA-CDs. The fluorescence intensity was first quenched by copper ions and recovered when DFX was added. Through the calculation of fluorescence recovery, the concentration of DFX was therefore determined. The optimized conditions were found at Cu2+ concentration of 20 μM, reaction time of DFX with Cu2+ of 30 s, methanol percentage of 30 % and pH value of 11. The limit of detection was found at 600 ng/mL. The linearity response for DFX was within the concentration range from 1 μg/mL to 10 μg/mL with a correlation coefficient greater than 0.9975. In intra-day (n = 3) and inter-day (n = 5) assays, the RSD values were less than 8.7 %, and the absolute RE values were less than 4.8 %. The method was further applied to real plasma samples from 5 β-thalassemia patients, and the RSD in the detection of real samples for successive 3 times were below 4.71 %. When the data of real samples was compared with that by using capillary electrophoresis (CE)-UV, the RE were below 4.78 %. The simple sensing technique for detection of DFX in plasma has been optimized, validated and applied in real samples and can be served as a tool for clinical survey.