Quantum dots conjugated E. coli living cells as fluorescent reporters to detect cytotoxicity of chemicals
Chouhan, Raghuraj Singh and Kolkar Mohammed, Javed Hussain Niazi and Qureshi, Anjum (2013) Quantum dots conjugated E. coli living cells as fluorescent reporters to detect cytotoxicity of chemicals. In: The Sixth International Exergy, Energy and Environment Symposium, IEEES-6, 1-4 June 2013, Rize, Turkey, Rize, Turkey (Accepted/In Press)
Quantum dots (QDs) have attracted a lot of interest for imaging, diagnostics and therapy due to their bright, stable fluorescence. Surface activated QDs can be conjugated to a variety of bio-active molecules for binding to bacteria or mammalian cells for various applications. In the current work we report on; (a) controlled bioconjugation of carboxylic-CdTe QDs with gram negative E. coli and (b) determining the effect of fluorescent properties of QD-E.colil bioconjugates upon exposure to toxic chemicals. For this, first the cells were bioconjugated with non-toxic, capped and water-soluble CdSe quantum dots (QD). Model toxic chemicals, such as pesticide (paraquat) and oxidative stress inducing chemical (H2O2) at concentrations ranging 0.5-5 mM were incubated with QD-E.coli bioconjugates. When these chemicals interacted with cells, the behavior of fluorescent QD-E.coli bioconjugates was altered by the stress imposed by chemicals and thus the fluorescent ability of QD-E.coli bioconjugate diminished with time and concentration of toxic chemicals. This stress is attributed to the damages occurred as a result of interaction of toxic chemicals to cell-wall or membrane of QD-E.coli bioconjugate and therefore, florescence signal was lost (Figs. 1 and 2.) The loss in fluorescence (signal off phenomena) of QD-E.coli bioconjugates can be used as probes to develop a variety of fluorescence based detection kits for the rapid determination of toxic drugs or food sample testing.
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