Visual detection of folic acid based on silica coated CdTeS quantum dots in serum samples

Currently, folic acid (FA) has been used as an effective biomarker for early diagnosis of many diseases, so it is of practical significance to explore an ideal material with excellent performance for sensing FA. Herein, a visual fluorescent probe was creatively designed by wrapping silica shell (SiO 2 ) on the surface of CdTeS quantum dots (CdTeS QDs@SiO 2 ). The color change of the samples could be easily recognized by the naked eyes and was analyzed based on the red, green and blue (RGB) values obtained using ImageJ software. A good linear relationship was fitted between the ratios of F 445 /F 680 and FA concentrations ranging from 5 to 80 μM (R 2 =0.992) with a limit of detection (LOD) of 0.30 μM. Additionally, the proposed fluorescent probe was applied to detect FA in serum samples with satisfactory results obtained and exhibited a great potential for the quantification of FA in clinical medicine.