Fluorescence detection of total count of Escherichia coli and Staphylococcus aureus on water-soluble CdSe quantum dots coupled with bacteria.
The aim of this paper was to demonstrate a fluorescence measurement method for rapid detection of two bacterial count by using water-soluble quantum dots (QDs) as a fluorescence marker, and spectrofluorometer acted as detection apparatus, while Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were as detection target bacteria. Highly luminescent water-soluble CdSe QDs were first prepared by using thioglycolic acid (TGA) as a ligand, and were then covalently coupled with target bacteria. The bacterial cell images were obtained using fluorescence microscopy. Our results showed that CdSe QDs prepared in water phase were highly luminescent, stable, and successfully conjugated with E. coli and S. aureus. The fluorescence method could detect 10(2)-10(7)CFU/mL total count of E. coli and S. aureus in 1-2h and the low detection limit is 10(2)CFU/mL. A linear relationship of the fluorescence peak intensity and log total count of E. coli and S. aureus have been established using the equation Y=118.68X-141.75 (r=0.9907).
Xue
Xiuheng
X
Engineering Research Center of Bio-Process, Ministry of Education, Hefei University of Technology, 193 Tun Xi Road, Hefei, Anhui 230009, China.
Pan
Jian
J
Xie
Huiming
H
Wang
Juhua
J
Zhang
Shuang
S
D019187:Cadmium Compounds; D015169:Colony Count, Microbial / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification*; D005453:Fluorescence; D045663:Quantum Dots; D018036:Selenium Compounds; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D014867:Water
D019187:Cadmium Compounds; D018036:Selenium Compounds; D014867:Water; C058667:cadmium selenide