title: Colorimetric detection of pathogenic bacteria using platinum-coated magnetic nanoparticle clusters and magnetophoretic chromatography.
abstract: A colorimetric method that uses platinum-coated magnetic nanoparticle clusters (Pt/MNCs) and magnetophoretic chromatography is developed to detect pathogenic bacteria. Half-fragments of monoclonal Escherichia coli O157:H7 (EC) antibodies were functionalized to Pt/MNCs and used to capture E. coli bacteria in milk. After magnetic separation of free Pt/MNCs and Pt/MNC-EC complexes from the milk, a precision pipette was used to imbibe the E. coli-containing solution, then a viscous polyethylene glycol solution. Due to difference in viscosities, the solutions separate into two liquid layers inside the pipette tip. The Pt/MNC-EC complexes were separated from the free Pt/MNCs by applying an external magnetic field, then added to a tetramethylbenzidine (TMB) solution. Catalytic oxidation of TMB by Pt produced color changes of the solution, which enabled identification of the presence of 10 cfu mL(-1) E. coli bacteria with the naked eye. The total assay time including separation, binding and detection was 30 min.
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
authors.forename: Donghoon
authors.initials: D
authors.lastname: Kwon
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
authors.forename: Sanghee
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
authors.forename: Myung Mo
authors.initials: MM
authors.lastname: Ahn
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
authors.forename: In Seok
authors.initials: IS
authors.lastname: Kang
authors.affiliation: Department of Food Science and Technology, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Ki-Hwan
authors.initials: KH
authors.lastname: Park
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea. Electronic address: jeons@postech.ac.kr.
authors.forename: Sangmin
authors.initials: S
authors.lastname: Jeon
mesh_terms: D000818:Animals; D001560:Benzidines / Q000737:chemistry; D002845:Chromatography / Q000295:instrumentation*; D003124:Colorimetry / Q000295:instrumentation; D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D006801:Humans; D018189:Immunomagnetic Separation / Q000295:instrumentation*; D057230:Limit of Detection; D008280:Magnetics / Q000295:instrumentation; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008892:Milk / Q000382:microbiology*; D010984:Platinum / Q000737:chemistry*
chemical_list: D001560:Benzidines; D058185:Magnetite Nanoparticles; C021758:3,3',5,5'-tetramethylbenzidine; D010984:Platinum
keywords: Colorimetric detection; Magnetophoretic chromatography; Pathogenic bacteria; Platinum nanoparticles