Green one-step pyrolytic synthesis of folic acid-derived carbon dots for sensitive turn-on fluorescence detection of cysteine

The purpose of the present study is to develop an easy and effective one-step pyrolytic method for synthesizing carbon dots (CDs) derived from folic acid (FA), denoted herein as FACDs. This method is green, inexpensive, and simplifies the synthesis of fluorescent carbon nanomaterials with enhanced and stable fluorescence. Moreover, the as-prepared FACDs are effective in the sensitive and selective detection of cysteine (Cys) by such a "turn-on" mechanism of fluorescence. FACDs have been able to realize a low detection limit of 1.7 × 10^-7 M and a wide linear range from 5.0 × 10^-7 to 8.0 × 10^-5 M, successfully restoring quenched fluorescence in the presence of Cys. Obtained results confirm FACDs as a trustful high-performance sensor for various biological and environmental applications and pave the way for facile and efficient fluorescence-based detection platforms.