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Correlative Light- and Electron Microscopy Using Quantum Dot Nanoparticles
Published on: August 7, 2016
A rapid and universal bacteria-counting approach using CdSe/ZnS/SiO2 composite nanoparticles as fluorescence probe
Xin Fu1, Kelong Huang, Suqin Liu
1Department of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China. fuxin1129@hotmail.com
Analytical and Bioanalytical Chemistry
|December 18, 2009
Summary
This study presents a new method for rapid bacterial counting using SiO(2)-coated CdSe/ZnS quantum dots (QDs). This fluorescence-based technique offers higher sensitivity for detecting total bacterial counts compared to traditional methods.
Area of Science:
- Nanotechnology
- Biotechnology
- Analytical Chemistry
Background:
- Accurate and rapid bacterial quantification is crucial for public health and industrial applications.
- Conventional methods like plate counting are time-consuming and may lack sensitivity.
- Development of sensitive, rapid, and reliable bacterial detection methods is ongoing.
Purpose of the Study:
- To develop a novel, rapid, simple, and sensitive method for total bacterial count detection.
- To utilize silica-coated cadmium selenide/zinc sulfide (CdSe/ZnS) core/shell quantum dots (QDs) as fluorescent markers for bacterial quantification.
- To establish a covalent linkage between QDs and bacteria for enhanced detection.
Main Methods:
- Synthesis of highly luminescent CdSe/ZnS quantum dots using non-pyrophoric precursors (cadmium oxide and zinc stearate).
- Preparation of CdSe/ZnS/SiO(2) composite nanoparticles via a reverse-microemulsion technique, resulting in a SiO(2) surface coating.
- Covalent conjugation of the synthesized QDs with bacteria using glutaraldehyde as a crosslinker.
Main Results:
- The synthesized CdSe/ZnS/SiO(2) nanoparticles exhibited high luminescence, biological functionality, and monodispersity.
- Successful covalent conjugation of the QDs with bacterial cells was achieved.
- The developed method demonstrated higher sensitivity, detecting bacterial counts as low as 3 x 10^2 CFU/mL.
- A linear correlation (R = 0.99574) was established between fluorescence intensity and bacterial count (3 x 10^2–10^7 CFU/mL).
- Analysis of seven real samples showed results consistent with the conventional plate count method, with satisfactory standard deviation.
Conclusions:
- The SiO(2)-coated CdSe/ZnS quantum dot method provides a sensitive, rapid, and reliable approach for total bacterial count determination.
- This QD-based fluorescence assay offers a significant improvement over conventional methods in terms of speed and sensitivity.
- The method's effectiveness was validated in real-world samples, indicating its practical applicability.
