A carbon-dot-based dual-emission probe for ultrasensitive visual detection of copper ions

Abstract

In this work, we successfully developed an ultrasensitive dual-emission fluorescent sensor (CRB) for instant visual determination of Cu²⁺ by modifying a Cu-sensitive rhodamine B derivative (RB) onto photostable carboxyl modified carbon dots (CDs). The RB moiety of the CRB was extremely sensitive to Cu²⁺ and exhibited significant orange fluorescence in 1 second, while the blue CD moiety was stable to Cu²⁺. As a result, significant fluorescent color transformation from blue to orange could be observed in the presence of Cu²⁺, which could be applied to rapid visualization of Cu²⁺. The CRB exhibited good selectivity and excellent sensitivity to Cu²⁺, and the detection limit (LOD) was estimated to be 2 ppb. Moreover, a portable test strip has been successfully developed and applied for the visual inspection of Cu²⁺, which provides a convenient and reliable approach to monitor Cu²⁺ on site without resorting to instrumental analysis.