title: A label-free electrochemical impedance immunosensor based on AuNPs/PAMAM-MWCNT-Chi nanocomposite modified glassy carbon electrode for detection of Salmonella typhimurium in milk.
abstract: A sensitive and stable label-free electrochemical impedance immunosensor for the detection of Salmonella typhimurium was developed by immobilising anti-Salmonella antibodies onto the gold nanoparticles and poly(amidoamine)-multiwalled carbon nanotubes-chitosan nanocomposite film modified glassy carbon electrode (AuNPs/PAMAM-MWCNT-Chi/GCE). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to verify the stepwise assembly of the immunosensor. Co-addition of MWCNT, PAMAM and AuNPs greatly enhanced the sensitivity of the immunosensor. The immobilisation of antibodies and the binding of Salmonella cells to the modified electrode increased the electron-transfer resistance (Ret), which was directly measured with EIS using [Fe(CN)6](3-/4-) as a redox probe. A linear relationship of Ret and Salmonella concentration was obtained in the Salmonella concentration range of 1.0×10(3) to 1.0×10(7) CFU mL(-1) with a detection limit of 5.0×10(2) CFU mL(-1). Additionally, the proposed method was successfully applied to determine S. typhimurium content in milk samples with satisfactory results.
authors.affiliation: College of Chemistry and Material Science, Shandong Agricultural University, Taian, 271018 Shangdong, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Dong
authors.forename: Han
authors.initials: H
authors.lastname: Zhao
authors.forename: Minrong
authors.initials: M
authors.lastname: Xu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Ma
authors.forename: Shiyun
authors.initials: S
authors.lastname: Ai
mesh_terms: D000327:Adsorption; D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D017097:Electric Impedance; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D005506:Food Contamination / Q000032:analysis; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D008892:Milk / Q000737:chemistry* / Q000382:microbiology*; D053761:Nanocomposites / Q000737:chemistry; D012486:Salmonella typhimurium / Q000737:chemistry / Q000302:isolation & purification*
keywords: Electrochemical impedance immunosensor; Gold nanoparticles; Multiwalled carbon nanotubes; Poly(amidoamine); Salmonella typhimurium