Aluminum foil as a substrate for metal enhanced fluorescence of bacteria
labeled with quantum dots shows very large enhancement and high contrast
Aktilek Akhmetova
Department of Chemistry, School of Science and Humanities,
Nazarbayev University, Nur-Sultan, Kazakhstan
Email: [email protected]
Abstract
The application of quantum dots (QDs) in the whole cell labeling is worth mentioning since it enables the
detection of pathogens and cell study. A very high surface/metal enhanced fluorescence was observed for
E. coli bacterial cells labeled with CdSeS/ZnS core-shell type QDs on three substrates: aluminum foil,
aluminum film, and gold film. The enhancement factors relative to maximum fluorescence intensity on
glass for those substrates were in the range of several hundred (up to 500) for two excitation wavelengths,
532 and 633 nm. The contrast as a ratio of signals from QD labeled to signals of QD unlabeled (control)
cells was also in the range of 100s for those substrates, and the highest contrast of 1050 was observed on
Al film. When CdTe QDs were used for labeling cells on all substrates or when fluorescence from cells
with both QDs was measured on silver film, low or no enhancement was observed. Overall, untreated
aluminum foil demonstrated great potential as a low-cost substrate for surface/metal enhanced fluorescence,
which delivered even more reproducible signals comparing to the gold film.