Detecting CdSe Nanomaterials with a Fluorescent Schiff Base Ligand

We investigated the easily synthesized ligand H3L as a fluorescent chemosensor for the detection of CdSe nanoparticles (CdSe NPs) and L-cysteine-capped CdSe quantum dots (CdSe-Cys QDs) in ethanol-water samples. A drastic quenching of the fluorescence emission of H3L at 510 nm occurred, as a result of the addition of CdSe NPs and CdSe-Cys QDs. A solution of H3L (1.26 ppb) showed sensitive responses to both CdSe NPs and CdSe-Cys QDs, with limits of detection (LOD) as low as 40 and 62 ppb, respectively. Moreover, using a smartphone color recognizer application, the fluorescence intensity response of H3L-modified cellulose paper to CdSe-Cys QDs was recorded on a red channel (R), which allowed us to detect CdSe-Cys QDs with LOD = 15 ppb. Interference of some common metal nanomaterials (NMs), as well as metal ions, in the determination of CdSe NMs in solution was studied. The affinity of H3L to CdSe NPs and CdSe-Cys QDs was spectroscopically determined. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), micro-X-ray fluorescence (mu-XRF), H-1-NMR, attenuated total reflection infrared spectroscopy (ATR-IR), and density functional theory (DFT) were also used to investigate the interaction of H3L with CdSe NMs.

Automated summary

We investigated the use of the ligand H3L as a fluorescent chemosensor for detecting CdSe nanoparticles and CdSe-Cys quantum dots in ethanol-water samples. Our results showed that H3L exhibited a significant fluorescence quenching when CdSe NPs and CdSe-Cys QDs were added. We were able to detect CdSe NPs and CdSe-Cys QDs with low limits of detection using H3L, and the fluorescence intensity response of H3L-modified cellulose paper allowed us to easily detect CdSe-Cys QDs using a smartphone color recognizer application.