Continuous Synthesis of Carbon Dots with Full Spectrum Fluorescence and the Mechanism of Multiple Color Emission

Carbon dots with different emission fluorescence have greatly potential applications for various areas from in vitro imaging and biotherapy due to good biosafety of red fluorescent CDs to efficient ion detection and photocatalysis due to excellent photoluminescence properties of blue fluorescent carbon dots. Traditional methods for the synthesis of full spectral carbon dots require 24 hours of synthesis and complex column chromatography. In this paper, a facile and efficient microfluidic method to continuously synthesize small and uniform carbon dots with emission fluorescence in full spectrum is first developed. The synthesis process could be reduced to 20 minutes. Through XPS analysis and DFT calculation, it is quantitatively revealed that the number of primary amino group determined the energy gap of carbon dots and thus determined the fluorescence emission wavelength of carbon dots. The applications in precise Fe3+ detection and in vitro bio-imaging successfully implement, showing carbon dots’ great potential application value.