Synthesis of biomass-based triple-emission carbon dots for dopamine sensing

Abstract

Biomass carbon dots (CDs) typically suffer from red fluorescence quenching in water, limiting their practical applications. This study introduces a simple pH regulation strategy to enhance water-solubility by converting lipophilic surface groups to hydrophilic ones. Using mugwort as a precursor, novel triple-emission biomass-based CDs (T-CDs) with good water-solubility were successfully synthesized. Comprehensive structural and spectral characterizations were performed to elucidate the properties of the T-CDs and the origins of their luminescence, providing valuable insights for the design of future CDs. The T-CDs were further modified with hexadecyl trimethyl ammonium bromide (CTAB), producing modified triple-emission CDs (mT-CDs) with enhanced photostability. These mT-CDs were effectively employed as fluorescent probes for selective dopamine (DA) sensing, achieving a linear range of 0.8 to 300 μM and a limit of detection (LOD) of 0.17 μM, demonstrating their potential in biochemical applications. To explore additional applications, mT-CDs were incorporated into polyvinyl alcohol (PVA) to create thin films. These films exhibit pink fluorescence under 254 nm UV light and phosphorescence after the UV source is removed, making them suitable for information encryption and anti-counterfeiting purposes.