| الوصف: |
In this work, carbon quantum dots were prepared from grapefruit peel as carbon source by microwave heating method. The prepared carbon quantum dots CQDs were analyzed by fluorescence spectroscopy, TEM analysis, XPS analysis, etc., as well as their optical properties were also investigated. The prepared CQDs have high green fluorescence with excitation wavelength of 320 nm and maximum emission wavelength of 415 nm. the average particle size is about 7.4 nm, uniform dispersion and good stability. And a FRET (fluorescence resonance energy transfer) based fluorescence method was constructed by combining carbon quantum dots with silver nanoparticles (Ag NPs) for the rapid detection of E. coli. Its fluorescence transduction is based on the spectral overlap between the donor (CQDs) emission and the acceptor (nanoparticles) absorbance. The fluorescence of the aptamer-attached CQDs is burst in the presence of and silver nanoparticles. Upon addition of the specific E. coli solution, an aptamer-target complex is formed and the preferential interaction of the aptamer with the specific bacteria leads to the release of CQDs and Ag NPs. After incubation time, the bacterial cells are centrifuged, leading to the precipitation of E. coli aptamer couples and Ag NPs, resulting in the recovery of CQDs fluorescence. This method allows specific detection of E. coli in a wide range of pathogenic bacteria. The final results showed that the linear range of the sensor was 2×103 ~ 2×108 CFU·mL− 1 and the detection limit for E. coli was as low as 77 CFU·mL− 1. |
