This invention relates to a sensor that detects
bacteria cells comprising (a) a primary negatively charged, nanoparticulate sensing material; (b) a secondary positively charged, fluorescent sensing material; (c) a housing; and (d) at least one illuminator; wherein said housing contains said primary negatively charged, nanoparticulate sensing material, said secondary positively charged fluorescent sensing material and a sample potentially comprising
bacteria in
aqueous medium, wherein said illuminator provides light of at least one pre-specified
wavelength λi to excite at least said secondary positively charged, fluorescent material, wherein said secondary positively charged, fluorescent material electrostatically attached to
bacteria cells provides at least one fluorescent response at a second different
wavelength λn wherein both i and n are integers, wherein said negatively charged, nanoparticulate sensing material electrostatically attached to said fluorescent material suppresses fluorescing of said fluorescent material at said second
wavelength λn; and wherein said housing permits illumination of the contents of said housing by said illuminator and wherein said housing further permits the detection of a fluorescent response at a second wavelength λn. The negatively charged material includes (dsDNA coated) spherical AuNPs and
graphene oxide (GO). The positively charged fluorescent material includes
water soluble cationic
conjugated polyelectrolytes (COPE) or positively charged
peptide /
polymer labeled with
fluorescence dye. The sensor makes use of the FRET phenomenon between the primary and secondary sensing materials. The sensor allows making a distinction between living and dead bacteria and can measure the total bacteria count. A method for detecting bacteria utilizing the sensor is another part of the invention.