Ali A. Ensafi, Sahar Haghighat Sefat, Nafiseh Kazemifard & Behzad Rezaei

Abstract
In the present work, an optical sensor for quantitative measurement of penicillamine (PA) was fabricated. In this optical sensor, carbon dots (CDs), which were synthesized from saffron, were used as a fluorophore. This fluorophore exhibited high fluorescence and stability in various medium. The emission light of the CDs could be absorbed by PA–Cu(II) complex via inner filter effect. This fluorescence intensity reducing was proportional to the concentration of PA in a constant concentration of Cu(II) and could be applied as an analytical signal for PA determination in the range of 0.05–13.0 μg/mL with a detection limit as 0.02 μg/mL. Under the optimum conditions, 0.5 and 9.0 μg/mL of PA solutions were measured five times, and the
results showed an RSD% of 1.9% and 2.3%, respectively. Finally, the suggested optical sensor was fruitfully used for PA measurement in human plasma samples.

Keywords Green synthesis · Carbon dots · Penicillamine · Fluorimetric sensor · Inner filter effect