Abstract
In this study, Mn‐doped ZnSe/ZnS core/shell quantum dots (CSQDs) were synthesized in aqueous solution using polyethylene glycol as a surface stabilizer and successfully applied in the detection of Escherichia coli O157:H7 and methicillin‐resistant Staphylococcus aureus (MRSA) for the first time. The CSQDs were conjugated with anti‐E. coli antibody and anti‐MRSA antibody via protein A supported by 1‐ethyl‐3‐(‐3‐dimethylaminopropyl)carbodiimide hydrochloride for fluorescent labeling of the intact bacterial cells. The detection was performed for the bacterial strains cultivated in Luria‐Bertani liquid medium. The obtained results indicate that E. coli O157:H7 and MRSA can be detected within 30 min at a high sensitivity of 101 CFU/mL. This labeling method based on the highly fluorescent CSQDs may have great potential for use in the food industry to check and prevent outbreaks of foodborne illness.
Highlights
Development of semiconductor nanocrystals or quantum dots (QDs) has been attracted great attention in the past decades due to their potential applications in molecular and cell imaging, biological probes, solar conversion components, optoelectronic components, and light-emitting devices [1,2,3]
Two strains of E. coli O157:H7 and MRSA were provided by the Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City. e strains were stored at −20°C in 20% glycerol until their use
The strains were cultured on Luria-Bertani (LB) medium at 37°C overnight, and the initial concentration of bacteria was determined by using the plate counting method. e bacterial strain cultures were washed and diluted to a final concentration of 106 CFU/mL by phosphate buffered saline (PBS), which was prepared by dissolving 8 g NaCl, 0.2 g KCl, and 1.44 g KH2PO4 in 1L distilled water and adjusted its pH to 7.4
Summary
Development of semiconductor nanocrystals or quantum dots (QDs) has been attracted great attention in the past decades due to their potential applications in molecular and cell imaging, biological probes, solar conversion components, optoelectronic components, and light-emitting devices [1,2,3]. Erefore, many research groups have paid attention to develop Cd-free QDs for optoelectronics and biological applications [8,9,10,11,12,13]. Transition-metal-doped ZnSe semiconductors have been intensively developed to increase fluorescence efficiency of bare ZnSe [17,18,19,20]. The bonds with Mn2+ on the surface of the nanocrystals have formed trapping states, affecting fluorescence and its quantum efficiency [22]. The bonds with Mn2+ on the surface of the nanocrystals have formed trapping states, affecting fluorescence and its quantum efficiency [22]. erefore, as the passive surface states become stable, the QD’s emission ability becomes better [23, 24]
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