pH selective fluorometric detection of E. coli using water soluble polyphenothiazine

This work has investigated the use of a novel cationic conjugated polymer, Poly 10-(6-(3-methylimidazolidin-l-yl)hexyl)−9-Phenothiazine (PMP), as a sensing platform for a polymer-based fluorescence sensor for the detection of E. Coli O157:H7. Fourier Transform Infrared Spectroscopy (FTIR), ultraviolet radiation (UV), proton nuclear magnetic resonance (1HNMR), and photoluminescence (PL) analysis were used to characterise the synthesised polymer. The electrostatic interaction between single strand genomic DNA of E.coli (tDNA) and cationic polymer resulted in photoinduced charge transfer (PET) mediated quenching of the fluorescence intensity of PMP, which has been utilized as a tool for the detection DNA of E. coli (tDNA), since the decrease in photoluminescence intensity of cationic polymer was found to be proportional to the concentration of tDNA. The biosensor developed using PMP exhibits sensitive detection of tDNAin the range of 10−18 to 10−21 M concentration with a lowest detection limit of tDNA is 1 × 10−21 M.