Fluorescent carbon dots with tunable emission by dopamine for sensing of intracellular pH, elementary arithmetic operations and a living cell imaging based INHIBIT logic gate.

Fluorescent carbon dots (C-dots) have drawn great attention in recent years, and many researchers have focused on developing preparation routes and broadening the applications of C-dots. In this work, novel luminescent C-dots with tunable emission were prepared by the pyrolysis of citric acid (CA) and dopamine (DA). By adjusting the molar ratio of CA and DA in the precursor from 2 : 1 to 2 : 3, the maximum fluorescence emission of the obtained C-dots is at 510 nm in acid solution, while it shifts to 450 nm under neutral conditions, and the fluorescence is quenched in a basic solution. By controlling the unique fluorescence emission at different pH values, a three-state switch is achieved. Half-addition and half-subtraction were performed at 525 nm and 450 nm emissions as outputs. And a living cell imaging based INHIBIT logic gate operation was achieved by imaging the channel ratio of the cells.