Application research of high fluorescence anti-counterfeiting ink based on L-histidine nitrogen-doped cellulose-derived carbon quantum dots

In this study, L-His-N-carbon quantum dots (CQDs) were synthesized via a microwave-assisted method using homemade hardwood cellulose with a dryness of 20% as the carbon source and L-histidine as the nitrogen source. The results demonstrated that when the mass ratio of cellulose to L-histidine was 1:5 and the reaction time was 40 min, the L-His-N-CQDs exhibited the highest fluorescence quantum yield of 22.43%. A series of characterizations revealed their superior fluorescence performance and uniform size distribution. Subsequently, L-His-N-CQDs were incorporated into a plant oil-based binder to formulate fluorescent anti-counterfeiting ink. Adjusting the mixing ratio of tung oil and soybean oil effectively regulated the ink's drying properties. When the tung oil-soybean oil ratio was 2:1 or 3:1, the ink achieved optimal drying properties, transparency, and fluidity, ensuring excellent printability and anti-counterfeiting performance in screen printing. Fluorescence spectroscopy tests indicated that the composite fluorescent anti-counterfeiting ink possessed remarkable extended fluorescence stability and anti-quenching properties. The ink's resin binder, plant oil solvent, and additives did not hinder the luminescence of carbon quantum dots. Thus, the prepared ink is highly applicable in anti-counterfeiting printing technologies and related fields, offering new material options for such printing techniques.