Highly fluorescent carbon dots from enokitake mushroom as multi-faceted optical nanomaterials for Cr6+ and VOC detection and imaging applications

Abstract

Carbon dots are optically unique materials for sensing applications that can be prepared from various raw natural materials. In this work, highly fluorescent carbon dots were synthesized from enokitake mushroom via a one-step hydrothermal method in the presence of diluted sulfuric acid. The spherical carbon dots, with an average diameter of 4 nm, exhibited blue photoluminescence under UV illumination and a quantum yield of 11%, increasing to 39% upon passivation with tetraethylenepentamine. We employed both photoluminescence and light absorption properties of carbon dots for Cr6+ and volatile organic compound (VOC) sensing. Their fluorescence emission was selectively quenched by Cr6+ with a limit of detection of 0.73 µM. A fluorescent colorimetric paper-based device was fabricated and demonstrated to determine Cr6+ at concentrations as low as 10 µM. The carbon dots were also shown to have sensitivity and selectivity towards VOCs when integrated into an optical electronic nose. They were then used successfully to determine alcohol contents in aqueous solutions and ethanol concentration in a real spirit sample. They were further tested as a fingerprint detection agent and fluorophore for the manufacture of fluorescent plastics. Our results demonstrated that enokitake mushroom can be used to produce multi-faceted carbon dots with diverse applications.