Bright hydrophilic and organophilic fluorescence carbon dots: One-pot fabrication and multi-functional applications at visualized Au3+ detection in cell and white light-emitting devices

•HCDs and OCDs were prepared simultaneously by facile one-pot hydrothermal process.•HCDs and OCDs showed bright white and blue fluorescence under UV light of 365 nm.•The HCDs were successfully used for bioimaging and biosensing of Au3+ in PC12 cells.•The HCDs could be used for fabricating the white-light-emitting devices.