A dual-mode sensing platform coupling two-signal ratiometric and colorimetric methods for detecting Au³⁺ based on...

The considerable risk posed by Au³⁺ residues to the environment and human health has sparked interest in researching Au³⁺ monitoring techniques. The detection results in the usual ratio mode are more reliable. In this work, we develop a dual-mode strategy based on reducing carbon dots coupling with two-signal ratiometric and colorimetric methods for high-sensitivity, good-selectivity, and wide-range detection of Au³⁺. Cyan carbon dots (C-CDs) were synthesized by a simple and efficient one-step hydrothermal method. The C-CDs with rich amino group used m-phenylenediamine as carbon source, which made it have the potential as a reducing agent. After the addition of Au³⁺, Au³⁺ was reduced to Au⁰, generating stable gold nanoparticles (AuNPs). The fluorescence signal (F₄₉₀) of C-CDs decreased. At the same time, the large size of AuNPs enhances the second-order scattering signal (S₇₇₀) and produces the UV-visible absorption peak of AuNPs. Therefore, the dual-mode sensing strategy combining S₇₇₀/F₄₉₀ ratiometric and colorimetric detection of Au³⁺ is realized with high accuracy and sensitivity. Au³⁺ was determined in real samples and a good recovery was obtained. The dual-mode method has good performance and practicality, so it shows great potential for environment testing in a simple and reliable way.