One step synthesis of functionalized carbon dots for the ultrasensitive detection of Escherichia coli and iron (III)

In this paper, we report a single step solid phase synthesis strategy for colistin modified fluorescent carbon dots (CDs@colistin) for the selective detection of gram-negative bacteria like Escherichia coli. Colistin is a well known cyclic polypeptide antibiotic drug but here we have used as a binding ligand for E. coli. Here also, the synthesised CDs@colistin are used for selective Fe3+ metal ion detection. The detection limits are 460 cfu/mL for E. coli and 56 nM for Fe3+ with a linear range of 3.81 x 10(2)-2.44 x 10(4) cfu/mL and 0-48 mu M, respectively. The synthesised CDs@colistin are well dispersed in water with an uniform particle size ranging from 2 nm to 5 nm executing high quantum yield of 7.56%. The synthesis process of CDs@colistin is simple, cheap, and less time consuming. Simultaneously, we have applied CDs@colistin as a novel probe for E. coil detection in three different real samples like human urine, apple juice, and tap water to evaluate the practical applicability of the synthesised colistin conjugated carbon dots. (C) 2017 Elsevier B.V. All rights reserved.