Chemical toxicity detection using quantum dot encoded E. coli cells
Chouhan, Raghuraj Singh and Kolkar Mohammed, Javed Hussain Niazi and Qureshi, Anjum (2014) Chemical toxicity detection using quantum dot encoded E. coli cells. Sensors and Actuators B: Chemical, 196 . pp. 381-387. ISSN 0925-4005
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Official URL: http://dx.doi.org/10.1016/j.snb.2014.02.027
Bioconjugated quantum dots (QDs) with E. coli cells (bioconjugates) were employed as fluorescent switches that turn-off instantly against any cellular-stress caused by a toxic chemical. Paraquat (PQ), H2O2 and triton X-100 were used as models for assessing their toxicities on bioconjugates. These chemicals interacted on the cell-surfaces where QDs are harbored. The extent of toxicity imposed by chemicals on bioconjugates was successfully probed by (i) real-time fluorescence signals, (ii) visible changes upon UV-light illumination and (iii) scanning electron microscopic (SEM) analysis. Hierarchical cluster analysis using kinetic data of fluorescence and viable cell numbers showed a close relationship between structurally different compounds having similar toxic effects, such as PQ and H2O2, both induced toxicities through generating reactive oxygen species (ROS). In contrast, triton X-100 disrupted the cell–wall integrity and thus showed distinct response due to the loss of cell-bound QDs. Increasing cellular toxicity with chemicals thus followed the order PQ < H2O2 < TX100 confirming the inherent nature of model chemicals to induce cellular toxicity. Our results demonstrated a facile optical strategy that enables rapid and real-time cytotoxicity screening of potentially hazardous chemicals, such as new drugs that lead to ROS generation.
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