Mercaptopropionic acid capped ZnS:Mn/ZnS core/shell quantum dots as fluorescence probe for folic acid detection

In this work, high quality 3-mercaptopropionic acid (MPA) capped ZnS:Mn/ZnS quantum dots (QDs) have been synthesized via chemical precipitation approach. Structure analysis done by XRD and TEM shows that the prepared QDs are mono-dispersed with with a size distribution of 3-5nm. Optical features of the core/shell QDs have been characterized by UV-Visible spectroscopy and photoluminescence spectrometer (PL). The addition of folic acid (FA) to ZnS:Mn/ZnS QDs solution leads to a linear range of quenching of PL with the concentration of FA from 2μM/L to 60μM/L. It thus provides an opportunity to apply MPA capped ZnS:Mn/ZnS QDs as a sensitive fluorescence probe for FA detection. The detection limit is 0.48μM/L. The fluorescence quenching mechanism caused by FA was also studied.