Bright carbon dots as fluorescence sensing agents for bacteria and curcumin

Carbon dots (C-dots) are fluorescent nanomaterials that possess good photostability and low toxicity. They have been used as sensing probes and bioimaging agents for a variety of biological species. Numerous methods are available to generate C-dots. Nevertheless, simple and straightforward synthesis methods must be explored for the synthesis of C-dots from inexpensive, natural sources. In this study, we developed a simple method to generate C-dots from inexpensive chicken egg whites through a one-step heating reaction. The size of the generated C-dots was 3.3 ± 0.4 nm, and the quantum yield of the C-dots was as high as ∼43%. The as-prepared C-dots can be used as multicolor labeling agents for bacteria such as Staphylococcus aureus and Escherichia coli. Furthermore, the generated C-dots can be used as Förster resonance energy transfer sensing probes for curcumin, which is an active ingredient of turmeric and medicinal pigment. The feasibility of using the C-dots as selective sensing probes to determine the amount of curcumin from complex turmeric powder and condensed turmeric tablets is also demonstrated.