Abstract: The present invention relates, in general terms, to nanoparticle solutions, kits, devices and methods of use thereof. The present invention is suitable for use in quantifying bacterial cells in a sample. The method of quantifying bacterial cells in a sample comprises passing the sample in a liquid form and an aqueous nanoparticle solution through a porous substrate such that the bacterial cells in the sample is trapped on the porous substrate and can be quantified by a colorimetric and/or fluorescence output emitted from the nanoparticle bound to the bacterial cells.

Abstract: This disclosure 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. This disclosure further relates to a method for detecting bacteria cells.

Abstract: 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 ?i 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 ?n wherein both i and n are integers, wherein said negatively charged, nanoparticulate sensing material electrostatically attached to said fluorescent material suppresses fluorescing of said fluores