Fluorescent carbon dots for auramine O determination and logic gate operation

Carbon dots (CDs) with a fluorescence quantum yield of approximately 2.41% were prepared by simple one-step hydro-thermal synthesis of triethylenetetramine-N, N, N′, N″, N‴, N‴-hexaacetic acid (TTHA). The obtained CDs possess excitation wavelength-dependent and pH insensitive photoluminescence (PL) properties. Notably, the as-prepared CDs also exhibited unique auramine O (AO)-stimulus-responsive dual-emission fluorescence individuality, with which detection of AO using CDs has been performed through a fluorescence resonance energy transfer process. The fluorescence signals are linearly correlated with the concentration of AO over a range of 0.18–16.0   μM ( R 2   =   0.9989), with a limit of detection (3 σ ) of 54   nM. Additionally, a keypad lock and a NOR–AND logic gate was designed as well.