title: Rapid estimation of bacteria by a fluorescent gold nanoparticle-polythiophene composite.
abstract: Herein we present a facile method for rapid quantitation of bacterial cells over several logarithmic dilutions. The quantitation is based on loss of the fluorescence intensity of a positively charged Au nanoparticle-polythiophene composite in the presence of bacterial cells. The present method allowed estimation of both Gram-positive and Gram-negative bacteria with cells as low as 1000. Transmission electron microscopic investigations revealed attachment of the composite with bacteria with no discernible change in the morphology of the cells. Further, dynamic light scattering experiments indicated preferential attachment of smaller composite particles over larger ones, which were also attached at higher bacterial concentrations. The ease of operation with minimal sample manipulation steps, high sensitivity, quantitative detection, and its generality offer specific advantages over conventional methods.
authors.affiliation: Department of Chemistry, and Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam, India.
authors.forename: Biswa Ranjan
authors.initials: BR
authors.lastname: Panda
authors.forename: Atul Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Aiyagari
authors.initials: A
authors.lastname: Ramesh
authors.forename: Arun
authors.initials: A
authors.lastname: Chattopadhyay
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002470:Cell Survival; D015169:Colony Count, Microbial; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000494:pharmacology*; D006046:Gold / Q000737:chemistry*; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry*; D008828:Microbiological Techniques; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D012542:Scattering, Radiation; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D011108:Polymers; D013876:Thiophenes; C066730:polythiophene; D006046:Gold