title: Functionalized gold nanorod-based labels for amplified electrochemical immunoassay of E. coli as indicator bacteria relevant to the quality of dairy product.
abstract: In this paper, we report an amplified electrochemical immunoassay for Escherichia coli as indicator bacteria relevant to the quality of dairy product using the functionalized gold nanorod-based labels ({dAb-AuNR-FCA}). The {dAb-AuNR-FCA} labels were designed by exploiting silica-functionalized gold nanorods (AuNR@SiO2) as the carriers for immobilization of detection antibody (dAb) and ferrocenecarboxylic acid (FCA), in which dAb was used for recognition of E. coli and FCA tags served as signal-generating molecule. Greatly amplified signal was achieved in the sandwich-type immunoassay when enormous FCA linked to AuNR@SiO2. Compared with the commercially available {dAb-FCA}, the {dAb-AuNR-FCA} labels exhibited a better performance for E. coli assay due to the advantages of AuNR@SiO2 as carriers. Under optimal experimental conditions, it showed a linear relationship between the peak current of FCA and the logarithmic value of E. coli concentration ranging from 1.0×10(2) to 5.0×10(4) cfu mL(-1) with a detection limit of 60 cfu mL(-1) (S/N=3), and the electrochemical detection of E. coli could be achieved in 3h. Moreover, the proposed strategy was used to determine E. coli in dairy product (pure fresh milk, yogurt in shelf-life, and expired yogurt), and the recoveries of standard additions were in the range of 95.1-106%. This proposed strategy exhibited rapid response, high sensitivity and specificity for E. coli assay in dairy product, and could become a promising technique to estimate the quality of dairy product.
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China. Electronic address: zhangxinai@mail.ujs.edu.cn.
authors.forename: Xinai
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Liaocheng People׳s Hospital, Liaocheng 252002, PR China.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
authors.forename: Hongyin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shen
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
authors.forename: En
authors.initials: E
authors.lastname: Han
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
authors.forename: Xiaoya
authors.initials: X
authors.lastname: Dong
mesh_terms: D000907:Antibodies, Bacterial / Q000737:chemistry*; D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques; D003611:Dairy Products / Q000382:microbiology*; D055664:Electrochemical Techniques; D004566:Electrodes; D004926:Escherichia coli / Q000302:isolation & purification*; D005296:Ferrous Compounds / Q000737:chemistry; D005516:Food Microbiology; D006046:Gold / Q000737:chemistry; D007118:Immunoassay; D057230:Limit of Detection; D000075163:Metallocenes; D043942:Nanotubes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D005296:Ferrous Compounds; D000075163:Metallocenes; C032949:ferrocenecarboxylic acid; D006046:Gold; D012822:Silicon Dioxide
keywords: Dairy product; E. coli; Electrochemical immunoassay; Ferrocenecarboxylic acid; Signal amplification; Silica-functionalized gold nanorods