Hydrodynamic cavitation synthesis of water-soluble CdSe quantum dots: Effect of venturi tube parameters on size distribution and fluorescence properties, with application in Fe detection.

Background: Fe is an important trace element in life metabolism and also the main component of industrial pollutant. How to improve the sensitivity of Fe detection is of great significance in biological and environmental analyses. Fluorescence probe for Fe detection has high sensitivity, but it is difficult to prepare a probe with high sensitivity. CdSe quantum dots (QDs) have the fast fluorescence response to Fe, which can be considered as an ideal fluorescent probe. In this study, CdSe QDs were prepared on large scale by the hydrodynamic cavitation (HC) technology using the physicochemical effect generated by cavitation bubble rupture.

Results: In venturi tube HC system, the sphalerite CdSe QDs (12 h) prepared by the control variable method have 1.83 nm average particle size, 1255 ns fluorescence lifetime and 87 nm Stokes shift. In addition, the prepared CdSe QDs (12 h) solution still has good stability after six weeks of storage. And then, the CdSe QDs (12 h) are used as fluorescence probe to detect Fe and the limit of detection is 4.98 μmol/L, which is better than most existing fluorescence probes reported in references. Moreover, the concentrations of purchased FeCl solutions are measured by using the fluorescence probe method and the measured results are comparable with those obtained by using the inductively coupled plasma emission spectrometer. This indicates that this method can be used to determine the concentration of Fe in real samples, which has a high accuracy.

Significance: In this work, CdSe QDs prepared by HC method is used as fluorescence probe to detect Fe. This research not only provides reference for the large-scale preparation of CdSe QDs, but also helps to understand CdSe QDs detection mechanism as fluorescence probe. The CdSe QDs as probe for Fe analysis have the advantages of low limit of detection and high sensitivity. This has potential applications for Fe accurate detection in life medicine and materials science.