One-step green synthesis of carbon dots derived from Plumeria alba flowers for sensing and bioimaging

Abstract

Carbon dots (CDs) prepared from biomass exhibit excellent potential for use in sensing and bioimaging due to their charming properties. In this paper, CDs were successfully synthesized from Plumeria alba flowers as the raw material by a low-cost and green hydrothermal method for the first time and exhibited good water solubility. Ammonia and sodium hydroxide were added to the biomass solution to regulate the luminescence of the CDs. Among them, blue fluorescent CDs (B-paCDs) synthesized with ammonia as the solvent were used to specifically identify and detect Cu²⁺ in water. Linearity within a range of 0.1–100 μM was achieved, with an LOD of 0.08 μM. Green fluorescent CDs (G-paCDs) synthesized in a sodium hydroxide solvent were applied for pH detection. When the pH increased from 2 to 9, the green fluorescence emission region showed significant linear enhancement. In addition, a smartphone-based handheld platform was employed to directly capture and analyse fluorescence photographs, which could be further extended to the analysis of river water samples. Finally, two kinds of CDs were applied for the fluorescence imaging of living cells (HepG2 cells). The constructed platform indicates that the as-synthesized CDs have promise for applications in the fields of sensing and bioimaging.