Folic acid incorporated nitrogen-doped carbon dots as a turn-on fluorescence probe for homocysteine detection.

This study describes the development of a low-cost fluorescence assay for detecting homocysteine (Hcy) without the interference of cysteine and glutathione using carbon quantum dots. Herein nitrogen-doped carbon quantum dots (NCDs) were synthesized from citric acid as the carbon source and urea as the dopant using a one-pot microwave-assisted method. The obtained NCDs were incorporated with folic acid (FA) by the direct ex situ addition method and were used as a fluorescence probe to detect Hcy. The probe exhibited a fluorescence turn-on response with increased Hcy concentration up to 50 µM with a limit of detection of 2.276 µM. The point of care detection of Hcy using the probe was also tested with a paper-based assay strip.